Eur Spine J (2000) 9 : 314–364 © Springer-Verlag 2000

P O S T E R P R E S E N TAT I O N S 1

LUMBAR DISC EXCISION BY MIDLINE EXTRA-DURAL ENDOSCOPY S.A. Abdul Gaffar, A. Ali Al-Khalifa, G.A. Basheer Bahrain Defence Force Hospital, P.O.Box – 28743, Bahrain This is a study on the results of fifty consecutive patients who underwent endoscopic removal of herniated lumbar disc by interlaminar extra-dural approach. The indication for surgery was single level, unilateral sciatica. After localising the disc space by X-ray, two 5 mm portals were made, one for an arthroscope and the other for working instruments. The spinal canal was entered through the interlaminar route and under direct vision the herniated disc was removed. The duration of study is from February 1998 to July 1999 with a mean follow-up of 14.58 months.There were 31 herniated, 9 extruded and 10 sequestrated discs. All patients were mobilized on the same day of surgery and 42 discharged the next day. Two patients suffered partial but permanent iatrogenic nerve root damage; 4 had post-operative head ache and one developed transient extra-pyramidal symptoms. Modified McNab criteria were applied to study the results by an independent observer. 40 patients (80%) had a very good outcome (i.e. fully functional with occasional discomfort); 5 patients had a good outcome (i.e. normal function with some restriction to strenuous activity); 2 patients with root damage were considered as fair results. 3 patients had recurrent disc herniation and were classified as failures. We conclude that this technique is a minimally invasive procedure with results comparable to conventional disc surgery. The advantages to the surgeon are excellent illumination, magnification and visualization. The advantages to the patient are minimal surgical trauma and speedy recovery. A video on the technique will be presented.

2 SIGNIFICANCE OF SPINAL INSTRUMENTATION FOR THORACO-LUMBAR SPINAL INFECTION S. Akagi, I. Kato, K. Sasao, T. Saito Dept. of Orthopedic Surgery, Kansai Medical University, 10–15 Fumizono, Moriguci, Osaka, Japan Retrospective clinical study of patients with thoraco-lumbar spinal infection, treated with debridement and bone graft with/without posterior spinal stabilization was performed, to evaluate the significance of spinal instrumentation for treatment of thoraco-lumbar spinal infection. Material & methods: Surgical results of 29 patients with pyogenic (16 patients), TB (11 patients) and fungal (2 patients) spondylitis, were reviewed. Levels of lesion included thoracic in 8, thoraco-lumbar junction in 8, lumbar in 9 and lumbo-sacral junction in 3. One patient had multiple lesions in cervical, thoracic and lumbar spine. Out of 29, 17 patients were combined with posterior spinal instrumentation at one stage (inst. group), 11 patients were performed ant. debridment and bone graft alone (non-inst. group). The remaining one was performed only posterior decompression. Indication for surgery included neurological deficit (21 patients), and abscess formation resisted to conservative treatment (8 cases). The average follow up period is 26 months (12m-84m.). Results: Operation time and blood loss in each group were 268 min and 604 ml in non-inst. group, and 342 min and 832 ml in inst. group respectively. There was no significant difference between two groups. In the cases of TB spondylitis, the duration of immobilization after surgery was 16 days in inst. group and 98 days in non-inst. group. In the cases of pyogenic spondylitis, it was 13 days and 26 days respectively. Further surgery due to recurrence was required 1 case in each group. Conclusions: Combination of spinal instrumentation for treatment

of thoraco-lumbar spinal infection does not increase the recurrence rate and also allows early mobilization of the patients, especially in the case of TB spondylitis. The clinical and radiological results were evaluated in each group and discussed the significance of spinal instrumentation for treatment of thoraco-lumbar spinal infection.

3 EFFECT OF PREOPERATIVE CHEMOTHERAPY ON THE OUTCOME OF SURGICAL TREATMENT OF VERTEBRAL TUBERCULOSIS – RETROSPECTIVE ANALYSIS OF 434 CASES E. Alici, Ö. Akçali, H. Tatari, I. Gunal Dokuz Eylul University Department of Orthopaedics and Traumatology, Balçova, Izmir, Turkey Preoperative chemotherapy regimen is a traditional treatment method in the surgical treatment of vertebral tuberculosis. A retrospectine analysis of 434 cases of vertebral tuberculosis who were treated surgically between 1975 and 1993, were performed with special reference to the preoperative duration of chemotherapy. 376 cases had four weeks of chemotherapy regimen with isoniasid, rifampin, and ethambutol, and in two of them re-activation of the disease was observed. On the other hand, 58 cases underwent operation for neurologic impairment with 6 to 18 hours of the same chemotherapy regimen and in no case re-activation occured. These results suggest a shorter duration of chemotherapy may be utilized in all patients undergoing surgical treatment for vertebral tuberculosis, providing a throughly debridement, leaving no necrotic or infected tissue behind.

4 POSTERIOR SPINAL FUSION USING BONE GRAFT SUBSTITUTES: PRELIMINARY FINDINGS N.K. Anjarwalla1, L. Banks2, S.P.F. Hughes1 1Department of Orthopaedic & Trauma Surgery, Imperial College School of Medicine, Charing Cross Hospital, London UK; 2Department of Radiology, Hammersmith Hospitals Trusts, London UK Introduction: Graft harvesting morbidity for posterior fusion has stimulated the development of graft substitutes. Bioglass 45S5; a melt derived glass composed of sodium, calcium, silicon and phosphate, in vitro stimulates osteoblast proliferation and matrix production that becomes calcified to produce bone nodules. Animal studies show it to be as efficacious as autologous bone. The aim of this study was to show that Bioglass is a safe bone graft adjunct in spinal fusion surgery. Background: Patients undergoing lumbar posterior spinal fusion were randomly allocated to two groups; group one- fusion supplemented with autologous bone only, group 2 – autologous graft on one side of their spine and a 50/50 mixture of autologous graft and Bioglass® on the other. Independent observers assessed function (Oswestry Disability Index {ODI}), pain (visual analogue scales {VAS}), on all patients and radiographic and bone densitometry on group 2. Assessments were repeated post operatively and at 1, 3, 6 and 12 months following surgery. Randomisation occurred in theatre. Results: There was good/excellent results in 60% of the patients. There was a marked change in pain (p<0.05) and ODI scores (p<0.01) in the Bioglass group. Patients were clinically fused and were no longer unstable by 6 months with no significant difference between the two groups.

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Initial (n=10) 6 month (n=10)

Pain

ODI

6.4±3.6 3.6 ±3.8

44.2±18.1 60.0 ±20.5

Discussion: A satisfactory fusion may be achieved with a 50/50 mixture of and autlogous bone. The results from surgery using this method were also clinically satisfactory. The use of Bioglass® in fusion surgery will reduce the need of bone graft harvesting and hopefully reduce patient morbidity. 5 ABNORMAL DISCHARGES OF THE RAT SPINAL DORSAL HORN NEURONS AFTER APPLICATION OF NUCLEUS PULPOSUS H. Anzai1, S. Konno1, S. Kikuchi1, K. Olmarker2 1Department of Orthopaedic Surgery, School of Medicine, Fukushima Medical University, Fukushima City, 960-1295 Fukushima, Japan; 2Department of Orthopaedics, Gothenburg University, Sahlgren Hospital, 413 45 Gothenburg, Sweden Aim: To examine if the application of nucleus pulposus (NP) on the spinal nerve root enhances neuronal activities of wide-dynamic-range (WDR) and nociceptive-specific (NS) neurons in the dorsal horn. Material and methods: The L5 nerve root and the corresponding lumbar spinal cord were exposed in 14 rats. Spontaneous discharges and responses to noxious and innoucuous stilmuli to their hind paw were recorded extracellularly as C-fiber single unit activities from the dorsal horn neurons. The rats were divided into 4 groups and neuronal activities were observed for 2.5 hours. In group A (n=6), the L5/6 disc was incised with needle and herniated NP was placed onto the L5 nerve root. In group B (n=2), the disc was left intact without incision and NP from tail was applied onto the nerve root. The other rats recieved fat in a similar fashion with (group C, n=2) or without (group D, n=4) incision of the disc. Results: In group A and B, the number of spikes at spontaneous discharges of each neuron remarkably increased and the responses to noxious pinches and electrical stimuli were enhanced at 2 hours after NP application, while responses to innoxious stimuli were not changed. In group C and D, responses to stimuli were not enhanced after application of the fat. Conclusion: This study demonstrated that the NP on the exposed nerve root induced abnormal changes in neuronal activities. This suggests that some factors in the NP may have a role in the induction of low back pain and sciatica. 6 SURGICAL MANAGEMENT OF THE ISOLATED SACRAL BONE TUBERCULOSIS IN HEMOPHILIC PATIENT M. Arazi, M.I.S. Kapicioglu, H.M. Özdemir, M. Yel Selcuk University Medical School, Department of Orthopaedic Surgery and Traumatology, TR-42080, Konya, Turkey Study design: A rare case is reported of the sacral bone tuberculosis in a hemophilic patient. Objective: To describe the diagnosis and succesful treatment of a hemophilic patient with sacral bone tuberculosis, with surgical intervention and chemotherapy. Summary of background data: Tuberculosis infection of the lumbosacral region is uncommon, with few reports in English literature. The isolated involvement of the sacrum is exceedingly rare and may be misdiagnosed as a tumoral or a pseudotumoral lesion in hemophilic patients.

Background: The patient was a 51-year-old man with a sacral spinal tuberculosis. After factor VIII substitution, the patient was operated through an anterior retroperitoneal approach and a large cold abscess localized at the presacral area was drained and curetted. No problem relating the bleeding disorder occured, in the postoperative course. Results: The diagnosis of spinal tuberculosis was confirmed histologically. The patient returned to full function after the surgery. Antituberculosis chemotherapy was administered for nine months, postoperatively. No obvious recurrence of the lesion has been seen for 3 years. Conclusion: Isolated sacral involvement is very rare in spinal tuberculosis. In endemic and developing countries, spinal tuberculosis should be included in differential diagnosis of the suspected sacral lesions. Adequate substituiton therapy should be administered with care in patients with bleeding disorders, undergoing major surgery. 7 EARLY CLINICAL RESULTS USING A NEW EXPANDING CAGE FOR PLIF: A RETROSPECTIVE REVIEW OF 107 PATIENTS WITH 12 TO 40 MONTH FOLLOW-UP D. Attia Chirurgie Orthopédique et Traumatologie – Chirurgie du Rachis, Clinique Kennedy, Avenue JF Kennedy 26200 Montelimar, France Purpose: We report on the early clinical results in a retrospective series of 107 patients who have undergone PLIF with a new lumbar expanding cage. The VariLift™ Cage addresses many of the shortcomings of previous cage designs. In it’s unexpanded position, the smaller size allows for less bone resection and root retraction during insertion. After expansion the anterior aspect of the cage increases from 2 to 2.5 mm resulting in approximately 6°of posterior angulation. The promotion of lordosis during PLIF surgery helps maintain or correct any segmental sagittal imbalance and minimizes stresses on adjacent level. The cage is hollow with large side fenestrations resulting in an expanded internal volume for an increased volume of bone graft. Materials & methods: 107 consecutive patients underwent posterior lumbar interbody fusion by the author using the VariLift™ cage. There were 54 men and 53 women with a mean age of 43. Operative procedure consisted of a single level procedure in 88 patients and double level arthrodesis in 19 patients. Primary surgical indications were degenerative disc disease (n=56), spondylolisthesis (n=20), along with 31 patients who had undergone prior surgical interventions. Eleven of the spondylolisthesis patients underwent additional supplemental fixation. 2 patients who had the supplemental fixation were the first patients in this series with multilevel fusion and a learning curve must be considered in these cases. 2 other patients were supplemented with additional fixation due to several reasons including previous wide laminectomies and a resultant instability. Surgical technique consisted of minimal bilateral laminotomy preserving the midline ligamentous structures. The clinical results were analyzed according to the French Beaujon classification which rates low back and radicular pain, neurogenic claudication, neurological deficit, medication use and activities of daily life. Pre-operative and post-operative scores were compared. Relative gain and percent recovery were calculated. Fusion determined by ; absence of motion on flexion-extension radiographic views, the absence of radiolucency around a cage on the anteriorposterior, lateral and Ferguson radiographic views, and visible bone within the cages. Post-operative segmental sagittal alignment was measured across the fused segments. Results: Follow ranged from 12 to 40 months. There was a 91% satisfactory results, 5 poor results of which 2 required revision. Neither revision was due to implant failure. Overall there was a relative gain of greater than 50% post-operatively using the Beau-

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jon classification. Fusion was deemed solid by all radiographic criteria in 103/107 patients. In 4/107 patients asymtomatic radiolucency was seen around the cage. In these 4 patients no motion was detected on bending films. Of the 93 patients working pre-op, postop 68 patients returned to their previous job, 11 returned to a less strenuous position and 14 patients did not return to work. No patient’s symptoms worsened. With the exception of 2 cases of foot drop who had partial or complete recovery, complications were minimal; there were no cage breakage or migration. Segmental lordosis, measured on the fused discs at the last follow up showed a mean angle of lordosis of 6.9° (4.8° on L4-L5, 8° on L5-S1) Conclusion: The VariLift™ Cage represents the next generation of cage design. This PLIF technique resulted in a greater than 90% fusion rate, with a minimal of complications, good pain relief, and early recovery. 8 CLINICAL-BIOMECHANICAL COMPONENTS OF DEFORMATION OF THE SPINAL COLUMN I. Axenovitch Joó János u. 41. 3300 Eger, Hungary In this work we examine the possibility and development of scoliosis as a result of mechanical liability. In theoretical support of this premise we have worked out the method of mathematical modelling and some theoretically important theses have been tested in practice. Material and methods: In this work we have used the theoretical computer technology method of mathematical modelling, the single rhythm model of spinal column in the form of rectilinear spinal-axis of alternating hard spondyles and elastic vertebral discs. The model makes it possible to examine the relations of external loading of the spinal column and its linkage to the pelvis and the head. Based on calculations of mathematical model we have proved that the appearance and development of deformations of spinal column are possible because of its biomechanical character (1) – weight and lengths. At a group pf patients (60 people) with different kinds of kyphoscoliotical deformation and at a control group of patients (30 people) we have tested the general weights of body and head as well as the lengths of the spinal column. Results and discussion: The examination of the mathematical model of spinal column has proved our hypothesis about the occuring of deformations as spinal column at an early stage as a result of losing or stability, and points out that appearance and progression is possible because of the dependence of the mechanical characters of the spinal column. lengths, loading, etc. Calculating the test works we have got different forms of loss of stability according to different kinds os scoliosis. The theoretical possibilities given by the model have contributed to giving an attempt to work out the clinical-biomachanical criteria of simple scoliosis. This way, when determining the weight of head at the patients with deformation we have experienced that the weight of head is 6–12% of the total weight of the patient, within this the fluctuation of the weight of head between 6–9% can be found at the patients with non-progressive forms (45 people), the state between 9–12% can be found among patients with progressive forms. At the control group the weight of head accounted for 3–6% of the total weight of the patient. The length of the spinal column of the patients exceeded the length of the spinal column of the members of the control group for 10–20%, and besides the growth was proportional with the progressive forms of patients. This work gives possibility to work out the correct clinical-biomechanical criteria of appearance and progression of deformations of the spinal column.

9 CLINICAL AND FUNCTIONAL SITUATION OF ADULTS WITH IDIOPATHIC SCOLIOSIS. A COMPARATIVE ANALYSIS WITH NON-SCOLIOSIS INDIVIDUALS AND LOW-BACK SUFFERERS J. Bago Granell, J. Sirera, J.M. Climent, F. Pellise, C. Villanueva Hospital Sant Joan Alicante/Hospital Vall d’Hebron Barcelone, Spain Objective. To analyze the clinical and functional situation of a group of adult patients with idiopathic scoliosis in comparison with two other groups: a control group of non-scoliosis individuals and a group of patients with non-specific low-back pain. Material. A total of 251 individuals (222 females and 29 males) with a mean age of 38.1 years were included in the study. They were divided in three groups: group IS consisted of 88 patients having a diagnosis of idiopathic scoliosis treated non-surgically; group CONTROL consisted of 127 individuals without any antecedent of spinal disease; and the group LBP consisting of 36 patients controlled because a non-specific low-back pain. Groups did not differ in age, sex or other significant socioeconomic or demographic characteristic. Method. Each patient was interviewed and fulfilled the following questionnaires: presence of back pain in the last year and intensity on a scale 1 to 5; self-esteem and body image questionnaire (range 10–50); health perception questionnaire (range 6–24); physical activities capacity questionnaire (range 9–27), Roland-Morris disability scale (range 0–24) and Oswestry disability questionnaire (range 0–100). Results. In last year, the percentage of individuals reporting back pain was 100% in the LBP group, 69.3% in the CONTROL group and 68.2% in IS group. The mean intensity was 3.0, 1.9 and 2.6, respectively (p<0.00001). Average values of the questionnaires are depicted in the table. Groups

Health perception Physical activities Self-esteem Roland-Morris Oswestry

IS

Control

LBP

P

12.8 14.4 37.8 11.4 59.6

11.4 14.4 40.1 4.4 46.5

16.4 19.7 37.5 14.8 68.0

0.0000 0.0000 0.08 0.0000 0.0000

Conclusions. The prevalence of pain in the group of adults with idiopathic scoliosis is similar to that of control group. Pain is more intense and provokes a higher subjective disability. Patients with scoliosis have a perception of health status and physical capability similar to that of control group but self-esteem and body image is perceived slightly worst. Individuals with non-specific low-back disorders have the higher prevalence and intensity of pain and the worst disability scores. Except for body image, these individuals have the worst grade for health perception and physical capacity.

10 FRONTAL AND SAGITTAL PLANE ANALYSIS AFTER COTREL-DUBOUSSET INSTRUMENTATION AND HARRINGTON ROD SYSTEM IN RIGHT THORACIC IDIOPATHIC SCOLIOSIS H. Behensky, F. Landauer, M. Krismer Department of Orthopaedic Surgery, University of Innsbruck, School of Medicine, A-6020 Innsbruck, Austria

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Purpose: To evaluate whether CDI is better suitable than Harrington rod system for scoliosis correction in the frontal and sagittal plane. Material and methods: Out of preoperative standing radiographs of 229 patients 30 pairs of female patients, one patient with Harrington rod instrumentation (HRI) and the other with CotrelDubousset instrumentation (CDI), could be identified. Curves within pairs were comparable with regard to curve magnitude (thoracic and lumbar) and level of stable and neutral vertebrae. Follow up examination, including long cassette upright PA and lateral xrays of the spine were performed at least eight years postoperatively (mean follow up time for CDI patients was 128 months, for HRI patients 198 months). Results: Radiological data are shown in the following table HRI

CDI

p

fused segments

12 (10–14)

12 (10–14)

n.s.

FRONTAL PLANE Cobb thoracic preop. Cobb lumbar preop. Cobb thoracic follow up Cobb lumbar follow up correction thoracic curve (%) correction lumbar curve (%)

64 (48–105) 41 (19–70) 42 (21–67) 24 (5–43) 34 41

66 (53–91) 44 (24–66) 28 (20–53) 21 (3–42) 58 52

n.s n.s. 0.004 n.s. 0.0002 0.03

SAGITTAL PLANE Th5-Th12 preop. Th5-Th12 follow up L1-L5 preop. L1-L5 follow up L3-L5 preop. L3-L5 follow up

16 (3–34) 13 (4–32) 44 (30–67) 42 (27–65) 33 (22–48) 32 (21–49)

17 (2–38) 15 (5–30) 43 (26–63) 44 (22–61) 31 (21–39) 37 (24–50)

n.s n.s. n.s. n.s. n.s. 0.005

Cobb angles in degree, range in brackets, two sample t-test.

Conclusion: With Cotrel-Dubousset instrumentation better correction of the thoracic and lumbar curves and better restoration of the lumbar lordosis distal the fusion is achievable. 11 CHENAU BRACE IN RIGHT THORACIC ADOLESCENT IDIOPATHIC SCOLIOSIS H. Behensky, F. Landauer, M. Krismer Department of Orthopaedic Surgery, University of Innsbruck, School of Medicine, A-6020 Innsbruck, Austria Purpose: To evaluate whether vertebral rotation could be improved with Chenau brace in tratment of right thoracic adolescent idiopathic scoliosis (AIS), as this orthosis is said to be an inspiration-/derotation device. Material and methods: 54 girls, with right thoracic AIS were treated with Chenau orthosis over a minimum period of two years. Inclusion criteria were residual growth of at least two years prior to skeletal maturity and a thoracic Cobb angle between 20 and 40 degrees before therapy. Cobb angle and apex rotation (Perdriolle) were measured on long cassette upright PA x-rays. Measurements were taken before treatment, six months after starting therapy and at least one year after treatment. Compliance was judged by means of regular control examinations, obviously used brace and visible skin signs. Therefore two groups of patients were formed (A: good compliance, n=33, B: bad compliance, n=22). Results: In compliant patients continous curve correction was evident. Group B patients deteriorated (t-test; p=0.003). After six months therapy both groups demonstrated apex translation (A: p=0.0001, B: p=0.003) but no derotation of apex vertebrae. At fol-

low up in group A apex distance was unchanged, whereas an increase was evident in group B (t-test; p=0.04). Apex rotation deteriorated in both groups (no significant difference between groups). Results are shown in the table.

Start 6 months Follow-up

Good compliance

Bad compliance

Cobb

Apex Apex distance rotation (mm)

Cobb

Apex Apex distance rotation (mm)

31° 16° 25°

20 10 20

33° 4° 37°

22 16 28

8° 6° 10°

12° 10° 15°

Conclusion: Curve correction with Chenau brace in right thoracic idiopathic scoliosis is a translational process and can be determined as a shift of the apex vertebra to the center sacral line. Satisfactory results can be expected only in patients with good compliance.

12 STRAIGHT SPINES IN YOUNG ADULTS: THE EXCEPTION OR THE RULE? J.A. Bettany-Saltikov, P. van Schaik, J. Warren University of Teesside and Middlesbrough General Hospital, Middlesbrough, United Kingdom Background: The clinically significant threshold above which a scoliotic curve could be abnormal remains arbitrary. Data on normal adolescent and adult back shape are scarce. However clinical decision making based on subjective, visual criteria influences management. Aim: To produce measurable values of normal back shape, against which deformity could be defined. Background: 48 volunteering young adults perceiving themselves as “normal” participated in the study. All have been cleared previously by school screening. Their age (18–28 years old) precluded curve deterioration, but was close enough to adolescent measurements at the end of growth. Back shape was assessed with the ISIS system. Results: A minority of 8% showed no curve, with 54% a single curve and the rest a double one. Right spinal asymmetry (77%) was more frequent than the left (52%). Mean values and 95% confidence intervals were 16.1o (14.0o-18.2o) for upper spinal asymmetry, 13.4o (10.1o –16.6o) for lower lateral asymmetry, 24.9 mm (20.6 mm -29.2 mm) for thoracic kyphosis and 14.9 mm (12.5 mm -17.2 mm) for lumbar lordosis. Increasing upper lateral asymmetry correlated with decreasing thoracic kyphosis (p<0.01). Maximum skin surface angle correlated positively with only upper lateral asymmetry (p<0.001). Conclusion: Normal spines comprise of lateral asymmetries, where straight is the exception more than the rule. Scoliosis seems to be an exacerbation of this lateral asymmetry beyond 18o for the upper and 16o for the lower spinal asymmetry. Hypokyphosis is related to upper lateral spinal asymmetry. Skin surface angle is a very good indicator of only the upper lateral asymmetry. 13 VERY EARLY ON-SITE PHYSIOTHERAPY FOR HOSPITAL WORKERS WITH BACK PAIN N. Birch, K. Ayris, J. Owen, N. Orpen Department of Orthopaedic Surgery, Northampton General Hospital NHS Trust, Northampton, NN1 5BD, England

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Spinal pain is an important cause of work absence in hospitals. The majority of employees have low back pain with or without sciatica. In 1997 a survey of work absence in the surgical and medical directorates of Northampton General Hospital Trust was carried out. The hospital has 700 beds and employs more than 3,500 staff. The survey showed that on more than 3000 days staff were absent from work bacause of “back pain”. As a result funds were provided to employ a senior McKenzie trained physiotherapist to offer a service to hospital workers of very early treatment for back pain to try to reduce work absence. Since she was employed, the physiotherapist has treated 563 employees of the Trust. The majority were nurses. In the first year absence from work because of back pain fell to 46% of the pre-intervention level. During the second year of operation there has been a further 8% reduction in employee absence. There has been no identifiable increase in absence due to other conditions (e.g. respiratory or GI) that might suggest this intervention merely transferred a problem from one area to another. We have shown that in an occupational setting very early physiotherapy for back pain can be cost-effective and suggest a much wider adoption of this kind of intervention in industry. There has been no identifiable transfer of work absence to other causes of disability suggesting that a true reduction in work absence has been achieved. 14 TRICALCIUM PHOSPHATE AS A GRAFT FOR ANTERIOR CERVICAL FUSION S. Blagg, R.W. Marshall RoyaL Berks Hospital. Reading. Berkshire The standard method for Anterior cervical fusion uses iliac crest bone graft. There is often donor site morbidity. Other materials have been used but allograft has been found to give poorer fusion rates and Bovine bone has a high non union rate. Both of these carry the risk of infection. Tri-calcium Phosphate (TCP) is a synthetic ceramic which is biocompatible and eventually fully replaced by bone. We aimed to study whether this could be used as a reliable alternative to autologous bone graft. 37 consecutive patients in whom anterior cervical fusion was clinically indicated were recruited into the trial on a name patient basis. Anterior cervical fusion was performed by the senior author using the appropriate length TCP block with a trench vertebrectomy in double level fusions. A Cervical Spine Locking Plate was placed anteriorly over the levels fused. The average age at surgery was 51.5 years. Single levels were fused in 27 patients and double in 10. The average time to final review was 17.8 months and over 24 months in 12. At review there have been no failures of fusion. Complications include one plate which loosened and was replaced and one haematoma. The use of TCP removes the need for iliac crest bone graft and its associated morbidity. As it is a purely synthetic compound it carries no risk of disease transmission and is fully replaced by bone with time. We propose that this is a good alternative to Iliac crest graft in anterior cervical fusion. 15 THERAPEUTIC OPTIONS OF MINIMAL INVASIVE TECHNIQUE IN THE TREATMENT OF SPINAL FRACTURES H. Boehm, H. ElSaghir Department of orthopaedics, spinal surgery and paraplegia, Zentralklinik Bad Berka, Robert Koch Allee 9, 99437 Bad Berka, Germany Introduction: Recent investigations have shown, that exclusively posterior stabilization of thoraco-lumbar fractures is afflicted with

a substantial loss of correction. Therefore circumferential fusions are gaining importance. Aim of the work and methods: In order to avoid the disadvantage of intraoperative repositioning of the patient and to allow a simultaneous access to both operative fields, we developed a method of endoscopically assisted ventral and dorsal surgery in prone position. From may 1994 til may 1998 in 93 patients (67 male, 26 female) with an average age of 31.2 years (15–68) video-assisted ventro-dorsal spondylodeses in acute fractures (n=71) and posttraumatic kyphoses (n=22) were performed. In 35 patients the injured segment was situated between Th2 and Th11, in 45 individuals between Th11 and L2, in 13 cases between L2 and L4. In 69 patients the circumferential fusion was performed in one single, the prone position. One lung intubation was not necessary in all of these. Operative time for the whole procedure in prone position averaged 207 minutes (129–320), compared with 278 min (190–390) for the conventional thoracoscopical method with intraoperative repositioning. Results: The amount of correction in the conventional videoassisted technique in lateral position was 9.5 degrees (0–28), in prone simultaneous technique the correction averages 16.4 degrees (2– 32). As regards blood loss, complications and duration of chest tube, in this first series, no significant differences could be detected. Significance of the results: The endoscopically assisted circumferential (correction-) spondyldesis in prone position proved to be an adequate procedure in the treatment of acute fractures and posttraumatic deformities. Operative time can be reduced as well as the intraoperative requirements for personel and instruments. Due to improved possibilities of simultaneus manipulations the correction achieved in prone position is significantly better than in conventional thoracoscopical technique. 16 CAN ADCON-L BE USED SAFELY AND TO ADVANTAGE IN ALL FORMS OF SURGERY FOR DEGENERATIVE LUMBAR DISEASE? N.R. Boeree Southampton University Hospital, Department of Orthopaedics, Tremona Road, Southampton, Hants, UK Aim: A prospective study to evaluate the risks and benefits of Adcon-L in all forms of surgery for degenerative lumbar disease including posterior instrumented spinal fusion (PISF) with decompression, posterior lumbar interbody fusion (PLIF) and wide decompression. Relevance: Adcon-L is an absorbable mechanical and biologically active barrier gel. Studies have shown its benefit in lumbar discectomy, but its safety when used with spinal instrumentation or spinal fusion has not been established. This study presents the early results of a continuing evaluation of the use of Adcon-L in such procedures. Methods: Adcon-L has been used in 288 patients, all operated upon by the author and followed for a mean of 2.7 years: discectomy (41), decompression of stenosis (54), decompression and PSIF (96), PLIF (49), decompression and Graf ligamentoplasty (31) and revision discectomy or decompression (17). All adverse clinical events were documented. Any patients with late developing leg pain were independently evaluated by gadolinium enhanced MRI. Data was also gathered from a control group of patients undergoing similar surgery but without Adcon-L. Results: (Adcon group followed by control) Early wound seepage/infection: 1.7%, 2.7% (n.s.) Late Infection: nil, nil Pseudomeningocele: 0.7%, nil (n.s.) Late onset sciatica (fibrosis): 3.1%, 19.4% (p<0.001) Late onset sciatica (other causes): 2.4%, 5.3% (n.s.) Fusion rate: 93.1%, 91.1% (n.s.)

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Conclusions: Adcon-L can be used safely and to advantage in the full range of surgery for degenerative lumbar spine disease. Fusion rates are not affected and the incidence of peridural fibrosis is significantly reduced. 17 MOLECULAR COMPOSITION OF THE DORSAL CAPSULE OF THE LUMBAR FACET JOINTS IN DEGENERATIVE INSTABILITY B. Boszczyk1, A. Boszczyk2, A. Korge3, W. Boos1, R. Putz2, A. Büttner5, M.V. Benjamin4, S. Milz2 1Neurochirurgische Abteilung, Berufsgenossenschaftliche Unfallklinik Murnau, Professor-Küntscher-Strasse 8, D-82418 Murnau; 2Anatomische Anstalt, Pettenkoferstrasse 11, D-80336 München; 3Orthopädische Klinik Harlaching, Harlachinger Strasse 51, D81547 München; 4Anatomy Unit, School of Biosciences, University of Wales Cardiff, PO Box 911, Cardiff CF1 3US, UK; 5Institut für Rechtsmedizin, Frauenlobstrasse 7a, D-80337 München, Germany Hypertrophy of lumbar articular facets and dorsal joint capsule are well documented in degenerative instability, the molecular changes occurring in the extracellular matrix (ECM) are however unknown.The L4/L5 posterior articular complex was removed from seven individuals undergoing fusion for degenerative instability. After methanol fixation and decalcification in EDTA, specimens were cryosectioned at 12 µm and immunolabelled with monoclonal antibodies for collagen types I, II, III, V and VI; chondroitin-4 and 6 sulphates; dermatan and keratan sulphate; versican, tenascin, aggrecan and link-protein. Antibody binding was detected using the Vectastain ABC ‘Elite’ kit. Labelling patterns were compared to corresponding healthy specimens examined previously. In comparison, the degenerative capsule was more dense and hypertrophied and the enthesis more fibrocartilaginous, immunolabelling extensively for collagen type II, chondroitin–6-sulfate, chondroitin-4-sulfate, aggrecan and link-protein. The articular surface showed extensive evidence of degeneration, while in pronounced degeneration, the thickened capsular entheses encircled the articular facets dorsally. Bony spurs capped with regions of cartilaginous metaplasia were prominent in this region, the ECM labelling strongly for type II collagen and chondroitin-6-sulfate. Hypertrophy of lumbar facet joints in degenerative instability appears to be due to capsular enthesis thickening rather than enlargement of the articular facet. In view of the dorsal joint capsule helping to limit axial rotation as a wrap-around ligament, the molecular changes suggest rotational instability (as in degenerative disc disease) being a decisive factor in development of spondylarthropathy. Sagittal joint orientation in degenerative instability appears to be the result of reactive changes rather than a predisposing factor. 18 A CASE CONTROLLED TRIAL OF SURGICAL VERSUS NON SURGICAL MANAGEMENT OF SPINAL STENOSIS J. Braybrooke, P. Sell Department of Orthopaedics, Leicester General Hospital, Gwendolin Road, Leicester, United Kingdom Surgical randomised trials are the gold standard for determining best treatment but are extremely difficult to complete. This study was a case controlled cohort study of surgical patients matched for age, sex and most importantly disability. There are no similar studies reported. Background: A consecutive surgical cohort of 20 lumbar decompressions for spinal stenosis were identified. Prospectively gathered data consisted of Oswestry disability, low back outcome, vi-

sual analogue, modified somatic and modified Zung depression index. Patients were closely matched for diagnosis, age and disability to non-surgical controls that declined surgery. Follow up was 90% at two years. Results: The two groups were very similar. Two unrelated deaths occurred in the surgical group and two non-surgical patients declined follow-up. Av Av AGE ODS initially

ODS two years

MSP

MZD

VAS initially

VAS two years

Operative

60.5

58

48

7

29

7.7

5.4

Non-operative

60.7

59

51

9

29

7.9

6.3

There was no significant difference in Oswestry score or visual analogue between the two groups at follow up. ODS p=0.33 and VAS p=0.5. The surgical ODS improved with a p=0.06 as did the surgical VAS p=0.01. The non surgical ODS and VAS did not improve significantly p=0.1 for both. Discussion: There was no statistical significant difference in outcome between surgical and non surgical cohorts when carefully matched for disability. Both groups improved over two years. The surgical improvement was significant, the non surgical improvement was not.

19 THE LUMBAR ENDOSCOPIC MICRODISCECTOMY: MID-TERM ANALYSIS OF THE FIRST 100 CONSECUTIVE CASES M. Brayda-Bruno1, P. Cinella1, R. Monteleone1, M. Ceccopieri2 1San Donato Hospital Group, Spine Surgery Department; 2Anaesthesia and Reanimation Department, S. Siro Clinical Institute, Via Monreale 18, Milano, Italy Among the new endoscopic posterior techniques for the treatment of lumbar disc herniation, MED (MicroEndoscopic Discectomy), introduced by the americans Foley and Smith in 1996, is surely the most effective and even the most promising, in its actual METR’x version. In fact, thanks to this technique it’s possible to reduce both contained herniations or extruded and/or migrated fragments, as well as associated bone pathologies, like lateral stenosis or interapophisary osteophitosis. This endoscopic approach through the working tube allows the decompression of the nerve root with the same kind of approach in the open or microsurgical technique, but with a small skin incision and a minimum muscle-ligament damage. For these reasons the posterior low back pain is very mild, with the consequent possibility to lower the average hospital staying for a traditional lumbar disc surgery, and also to use METR’x as a “day surgery” procedure. Both general and peridural anesthesia can be used, with the patient in knee-pectoral position or in lateral decubitus.Our series include 103 patients who underwent lumbar disc herniation surgery from November 1997 until February 2000. The interesting results of these surgeries are analysed from a statistic point of view, with a 94% of excellent or good results. Only 7 patients continued to suffer from irritative radiculopaty and/or lumbago. Only one microsurgical open conversion was done for a big medial L3-L4 herniation, removed by bilateral access. We had three small dural tears that didn’t require any open conversion and didn’t cause any post-operative problems. Until now no recurrency was observed. The MED/METR’x endoscopy technique is now well established, and can be considered the new “gold standard” for the lumbar disc herniation surgery.

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20 MINIMALLY INVASIVE INSTRUMENTATION CORRECTION AND FUSION OF PRIMARY THORACOLUMBAR SCOLIOSIS H.U. Bueff, G.D. Picetti III The Permanente Medical Group Inc., Roseville,1600 Eureka Road, CA 95661 USA Introduction: To present an endoscopic technique for the treatment of thoracolumbar curves in patients with idiopathic adolescent scoliosis and evaluate the efficacy of this technique. Methods: Between February 1999 and January 2000, 10 patients with thoracolumbar scoliosis underwent endoscopic instrumentation, correction and fusion. Average curve size was 57 degrees (51–64 degrees). Multilevel endoscopic discectomy in the thoracic spine was performed in standard fashion.The lumbar spine was approached retroperitoneally through the bed of the 11 th rib. The diaphragm remained attached. Cannulated screws were inserted into the vertebral bodies under endoscopic and fluoroscopic control. Fusion was performed using rib graft sections in the thoracic spine and femoral rings in the lumbar spine. A 4.5 mm solid rod was inserted into the most distal screw. A right angle clamp was used to make a small opening into the diaphragm and the rod was reduced and fixed into the remaining screws from distal to proximal followed by compression. A TLSO was worn for three months. Results: Average follow-up was 6 months. Curve correction averaged 78%. Operative time was 5 hours 46 minutes average. The blood loss ranged between 150 cc and 550 cc.Hospitalization averaged 2.9 days; children returned to school after 2–4 weeks. The thoracic discs appeared to be fused at three to six months.The femoral rings started to incorporate after 6 months. Discussion and Conclusion: These preliminary results of this new technique are promising. Curve correction and improvement of sagittal balance were comparable to standard open procedures. This technique will warrant continued evaluation and follow-up. 21 RADIOMETRIC ANALYSIS OF ANTERIOR CORRECTION AND FUSION OF IDIOPATHIC THORACIC SCOLIOSIS WITH SPECIAL RESPECT TO THE LUMBAR SECONDARY CURVE V. Bullmann, U. Liljenqvist, H. Halm Dept. of Orthopaedics, Essen Medical School, Hufelandstrasse 55, D-45122 Essen, Germany Purpose of the study: Radiometric curve analysis of primary and spontaneous secondary curve correction after anterior correction and fusion in idiopathic thoracic scoliosis. Methods: 37 patients with idiopathic right-sided thoracic scoliosis were prospectively evaluated. All patients were operated either with the Zielke-VDS threaded rod or with the Halm-Zielke Instrumentation (a primary stable double rod instrumentation) with selective fusion of the thoracic curve from end- to end-vertebra. Follow-up averaged 21months (12–51months). Cobb angles of primary and secondary curves as well as apical vertebral rotation according to Perdriolle were measured. The sagittal profile was evaluated as well. Results: The Cobb angle of the primary curve ranged from 41 to 92° (averaged 62.8°) and was corrected by 65.3% to 21.8° (5–44°). Loss of correction averaged 4.4°. Apical vertebral rotation was corrected by 47.3% from 26.2° to 12.6°. The secondary lumbar curve measured 39.1° (18–57°) preoperatively (63% correction on the bending films) and was corrected spontaneously by 54.7% to 17.7° (-3–42°) without any loss of correction during follow-up. Apical vertebral rotation averaged 12.7° (0–30°) in the lumbar curve and corrected spontaneously by 17,3% to 10,5° (0–25°).

Thoracic kyphosis measured 24.8° (-2–55°) preoperatively and 30.2° (6–58°) at follow-up. Out of 11 patients with a preoperative hypokyphosis of less than 20°, 6 patients were corrected to normal kyphosis. The thoracolumbar junction and lumbar lordosis remained unchanged, there was no case of distal decompensation in either frontal or sagittal plane. Complications: Implant related complications were observed in 3 patients (rod breakage), but no pseudarthrosis occurred. Conclusion: Selective anterior correction and fusion in idiopathic thoracic scoliosis enables a satisfactory correction of both primary and lumbar secondary with a shorter fusion length compared to posterior fusion techniques. Derotation of the primary curve is excellent and superior to posterior fusion techniques. However, spontaneous derotation of the lumbar curves was minimal. 22 EARLY HYPEREMIA DEVELOPMENT IN SPINAL NERVE ROOTS EXPOSED TO AUTOLOGOUS NUCLEUS PULPOSUS G. Byröd, K. Olmarker, B. Rydevik Dep. of Orthpaedics, Gothenburg University, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden Introduction: It was recently demonstrated that epidurally applied nucleus pulposus can induce an early endoneurial edema in spinal nerve roots. The aim of the present study was to assess the possible presence of accompanying blood flow changes, indicating also circulatory changes in the nerve roots. Material and methods: In 12 pigs, the S2 and S3 nerve roots with their respective dorsal root ganglia (DRG) were exposed. Using laser doppler technique, baseline endoneurial blood flow in the nerve roots and DRG was recorded. Autologous nucleus pulposus (NP group, n=6) or retroperitoneal fat (Control group, n=6) was applied epidurally on the nerve roots and DRG. Blood flow then was recorded for two hours. Changes in blood flow were expressed in per cent of the baseline value. Results % Blood flow changes

DRG, NP-group DRG, Control Root, NP-group Root, Control

0 min

20

40

60

80

100

120

100 100 100 100

147* 104 158* 92

190* 94 160# 104

244* 95 251# 116

282* 98 251# 115

277* 95 286# 109

272* 98 271# 98

*=significant #=not significant

Discussion: The results demonstrate that autologous nucleus pulposus can induce a significant DRG hyperemia. They also indicate hyperemia at nerve root level, although the results for this group were not significant when compared with the control group. Both hyperemia and edema are parts of the early phase in inflammatory reactions. Their presence already two hours after the application of NP epidurally on spinal nerve roots thus indicate that NP possesses inflammatogenic properties which can lead to endoneurial vascular reactions. Such tissue injury phenomena might be involved in the etiology behind sciatica. 23 LONG-TERM RESULTS OF SIMULTANEOUS TWO-TEAM SURGERY IN THE CORRECTION OF POSTTRAUMATIC THORACOLUMBAR KYPHOSIS R. Chaloupka, O. Vlach, P. Messner, L. Ryba, V. Tichy, M. Krbec Orthop. Univ. Dept., Masaryk Univ. Hospital, Jihlavska 20, 639 00 Brno, Czech Republic

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Introduction. The development of posttraumatic kyphosis is observed in unrecognized fractures or in failed conservative or surgical management. The aim of this retrospective study was to evaluate the results of simultaneous two-team surtery in the correction of posttraumatic thoracolumbar kyphosis. Methods. The combined surgery was performed using right lateral decubitus position. Posterior midline and retroperitoneal thoracolumbar approaches allowed simultaneous osteotomy, decompression, correction and stabilization of the spine. Kyphosis angle was measured after Cobb’s method before and after surgery, and two years after surgery. Material. 24 patients (10 females, 14 males) were operated in an average age of 42 years. The average injury – surgery period was 62 months. There were fractures type A (Magerl et al.) in 11 cases, type B in 8, type C in 5 cases. The causes of kyphotization were unrecognized fractures (3), conservatively (14) and surgically (7) treated fractures. There were fractures of T11 (2), T12 (4), L1 (14), L2 (4). The simultaneous two-team surgery consisted of anterior decompression and osteotomy, fusion (Harms mesh 19times, grafts threetimes, cages twice), posterior osteotomy, fusion, transpedicular screw fixation (Kluger fixator 15times, Daniaux system 6times). Neural deficit was present in 12 patients, all patients suffered from deformity and back pain. Results. The average estimated blood loss was 2300 ml, the average operation time 4 hours. The average kyphosis angle +26° was corrected to +2°, two years after surgery the value of 6,5° was found. Significant loss of correction was observed in three cases (12° and 26°). All patients had significant relief of pain (VAS score improved from 6,4 to 4,5, Oswestry index from 47,8% to 36,3%). The complications included urinary tract infection (4), lung embolism (1), retroperitoneal bleeding (1), abscess formation (1), both requiring surgical treatment. Discussion. Majority of authors recommend combined surgery, single anterior or posterior surgery are seldom performed. Conclusion. Early combined surgical correction of symptomatic kyphosis is recommended, preventing permanent pain and secondary changes of the spinal cord. The best prevention of kyphotic deformity is an appropriate primary management of the fractures.

24 “VASCULAR TUNNEL” FORMATION TO IMPROVE THE EFFECT OF DECOMPRESSIVE DUROTOMY IN THE TREATMENT OF TRAUMATIC SPINAL CORD SWELLING A. Csókay National Institute of Traumatology, Budapest, Fiumei ˙t 17. 1081 Hungary Background: The role of decompressive durotomy has been controversial in the treatment of posttraumatic spinal cord swelling. Although some authors have observed benefits from durotomy performed using a variety of techniques, others have not. However, the operation can be complicated by ischemic necrosis of the portion of the spinal cord protruding through the dural opening, and postoperativ liquorrhoea. Therefore, we have developed a new surgical technique, to avoid the ischemic complications. Background: Three decompressive durotomy were performed on patients suffering from posttraumatic spinal cord swelling. The most significant feature of the operation, which represents the novel approach in this type of intervention, is that a so-called “vascular tunnel” which is prepared around the main veins and arteries of the herniated spinal cord to achieve local decompression of the vessels. Results: In this series of 3 patients the results were surprisingly good, in spite of complete severe spinal cord lesion. An unexpected neurological improvement was observed.

Conclusion: This operative technique is not only effective in reducing the intradural pressure but also helps to prevent the ischemic complication usually associated with decompressive durotomy. 25 CHILDBEARING, CURVE PROGRESSION AND SEXUAL FUNCTION – A LONG-TERM MATCHED FOLLOW-UP OF PATIENTS WITH ADOLESCENT IDIOPATHIC SCOLIOSIS A. Danielsson, A.L. Nachemson Department of Orthopaedics, Sahlgrenska University Hospital, Göteborg University, SE-413 45 Göteborg, Sweden Introduction: A consecutive series of patients with adolescent idiopathic scoliosis, treated between 1968 and 1977, either with distraction and fusion using Harrington rods (ST, 145 females) or with brace (BT, 122 females) were followed at least twenty years after completion of the treatment. Methods: A questionnaire concerning childbearing and sexual life was filled in by 94% of ST, 91% of BT female patients and a randomly selected, age matched control group of 90 females. Of patients, 129 ST and 105 BT also had a radiographic examination. Curve size (Cobb method) was measured on present and earlier examinations. Results: The mean age was 40 years for all groups. 85% of ST and BT patients and 82% of controls were, or had been, married. There was no significant difference of number of children born (mean ST 1.8, BT 1.9 and controls 2.0) between the groups. Patients in the BT group had a significantly higher age at first pregnancy (28.0 versus 26.6 in ST and 25.9 years in controls) and higher frequency of low back pain during pregnancy than ST group and controls. The rate of ceasarean sections were equal between the groups (10–14%, ns). Almost 30% of scoliosis patients (control group 14%, p=0.013) felt they were limited in their sexual function, mostly because of difficulties to physically participate in activities or self-consciuosness about appearance. Pain was a minor reason for limitation. There were no significant differences in curve progress with regard to age at first pregnancy or the number of pregnancies. 26 PULMONARY FUNCTION IN PATIENTS WITH ADOLESCENT IDIOPATHIC SCOLIOSIS 25 YEARS AFTER SURGERY OR START OF BRACE TREATMENT A. Danielsson, K. Pehrsson, A.L. Nachemson Department of Orthopaedics, Sahlgrenska University Hospital, Göteborg University, SE-413 45 Göteborg, Sweden Purpose: To determine the long-term outcome of pulmonary function in a consecutive group of patients with adolescent idiopathic scoliosis treated by posterior fusion (ST, n=156) or brace treatment (BT, n=127). Methods: Vital capacity (VC), Forced expiratory volume (FEV1) and Total lung capacity (TLC) were determined in 251 patients before treatment, 18 months postoperatively for ST and in 90% of all patients at present follow-up. The results were corrected for loss of height due to scoliosis. VC was calculated in % predicted according to height and age. Cobb angles on present radiography were measured. Smoking habits were recorded. An age and sex matched control group was also examined. Results: Mean VC increased from 3.1 liters before to 3.5 l after surgery and 3.6 l at present follow-up. VC in % predicted increased from 67 before to 73 after surgery and 84 (p<0.001) at present follow-up. In the BT patients the VC was 3.4 l before treat-

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ment and 3.8 l at present follow-up and in % predicted 77% and 89% (p<0.001) respectively. FEV1 and TLC also increased. VC in % predicted in the control group was 103%. Mean Cobb angle at present follow-up was 40 degrees in both patient groups. The present results of VC or FEV1 did not correlate to Cobb angles or smoking habits. Conclusion: A gradual increase in pulmonary function 25 years after surgery or brace treatment was found. VC was 85% of predicted normal. No risk factors for the reduction of pulmonary function could be identified.

Results: The average follow-up period for this study was 36,2 months (range, 19 to 54 months). Excellent and good results occurred in 80% and 20% of the patients. A good bony fusion was seen in all patients. Conclusions: The use of a carbon cage with allograft bone seems promising as an autograft replacement in the cervical spine. The graft appears to be extremely stable after a mean follow-up of 3 years. The incorporation rate is high and the complication rate non-existent. 29

27 CONTINOUS BUPIVACAINE INFUSIONS POST LUMBAR DISCECTOMY E. Davies, P. Heath, M. McLaren Department of Orthopaedics, Queen Alexandra Hospital, Portsmouth, UK This prospective randomised double blind trial assessed the efficacy of continous local anaesthetic infusions post lumbar discectomy. 22 patients under going lumbar discectomy were randomised to receive placebo or bupivacaine infusions. A continous infusion cathter was placed beneath the erector spinae fascia at operation. The patients received the infusions for 40 hours post operation. Patients were then assessed post operatively as regards analgesic requirements, mobility and visual analogue pain scores. Patients receiving the local anaesthetic infusion had significantly reduced pain scores and opiate requirements compared to the placebo group. Discharge was earlier in the placebo group. At two year follow up there were no clinical differences between the two groups. No complications were associated with this technique. This technique is recommended for improving patient analgesia following lumbar discectomy. 28 THE USE OF CARBON FIBER CAGES WITH ALLOGRAFT BONE IN ANTERIOR CERVICAL DISCECTOMY V. Debois1, K. Desmedt1, D. Berghmans1, P. Herregodts1, J. Vangeneugden1, R. Herz1, F. Vanhoenacker2, K. Van Wambeke2 1Department of Neurosurgery; General Hospital St.-Maarten, Rooienberg 25, 2570 Duffel, Belgium; General Hospital St. Augustinus, Oosterveldlaan 24, 2610 Wilrijk; 2Department of Radiology, General Hospital St.-Maarten, Rooienberg 25, 2570 Duffel, Belgium Study design: This study prospectively reviewed the clinical and radiographic results of a series of patients who underwent an anterior cervical discectomy because of a monosegmental soft cervical disc herniation. For intervertebral fusion a carbon fiber cage with allograft bone was used. Objective: To determine the efficacy of a carbon fiber cage with allograft bone as a replacement of autograft bone in anterior interbody fusion after discectomy for monosegmental soft cervical disc herniation. Summary of background data: Iliac crest bone graft is the gold standard for anterior interbody fusion of the cervical spine. Disadvantages of the use of autograft bone are the graft related complications at the fusion site and the morbidity at the donor site and the morbidity. In an attempt to avoid these complications the iliac crest bone graft was replaced by a carbon cage with allograft bone. Methods: In forty consecutive patients with radiculopathy due to monosegmental soft cervical disc herniaton an anterior microdiscectomy was performed with removal of the disc herniation. For intervertebral stabilisation a carbon fiber cage with allograft bone was used.

BONE MARROW CELLS ADDED TO CERAMIC FOR LUMBAR SPINE ARTHRODESIS: QUANTITATIVE EVALUATION OF BONE FORMATION ENHANCEMENT ON ANIMAL MODEL J. Delecrin, M. Romih, Y. Maugars, D. Heimann, N. Passuti Dept.of Orthopaedics, Hotel-Dieu Hospital, 44093 Nantes, France Introduction: The purpose of this study was to quantify the beneficial effect provided by the association of autologus bone marrow on calcium phosphate ceramics for intertransverse process lumbar spinal fusion using a rabbit model. Material and methods: Three different graft materials were compared: autologus iliac bone grafts used as a control group, macroporous biphasic phosphate calcium ceramics associated or not with a standardized bone marrow punction. Original feature consisted in performing at L4/L5 two independant grafting sites. Graft was fixed and spine stability was obtained by a posterior instrumentation. Past 6 weeks, fusion rate by manual test and bone formation by histomorphometric evaluation were compared. Variations of mineral density of graft and lumbar spine segments were measured at 1, 10 and 42 days. Results: The fusion rate between ceramic blocks and transverse processes was 92.5%. Bone formation was significantly increased (50% of enhancement) inside ceramics loaded with bone marrow cells. However spinal fusion wasn’t achieved with ceramic grafts because all blocks were fractured through the middle. The mineral density of ceramics loaded with bone marrow cells was significantly increased. In the control group fusion rate was 72% and bone mineral density on spinal segments that achieved fusion decreased significantly from adjacent segments. Discussion: Bone marrow cells added to ceramics enhanced highly bone formation rate. A relation was shown between mineral density increase and bone formation rate inside ceramic, also between bone mineral density lowering and achievement of mechanical fusion. Conclusion: This study quantified the interest to add cells on ceramics. X-ray absorptiometer appeared as a non invasive way to assess mechanical quality of spine fusion. 30 IDIOPATHIC SCOLIOSIS SURGERY WITH A “FRAME” I. Dockendorff, A. Marti Perez Valenzuela 1551 Dp. 62, Providencia, Santiago, Chile In the surgical correction of idiopathic scoliosis it is of the utmost importance to correct vertebral rotation as well as deviation, measured with the Cobb Method. It is still controversial whether a specific instrumentation corrects or improves the vertebral rotation. This rotation has its clinical expression in the rib hump or lumbar hump, which is the least accepted part of the deformity by patients. We consider that idiopathic scoliosis surgical correction with a “frame” is an adequate system, which fulfills the requirement of correcting the rib and lumber hump, providing good cosmetic results, which is one of the main purposes of the surgery. Twenty

323

consecutive patients with idiopathic scoliosis were surgically treated with the frame. All of them were operated on by the first author and were followed up for at least two years. Eighty-five percent of patients are women. Their average age at the time of the surgery was 14 years and 5 months. The mean pre-operative value of the thoracic curve was 540, and 460 for lumbar curve. The immediate post-operative values were 160 and 120, respectively. At the end of the follow-up period the measurements were 170 and 150, respectively. Rotation measured by the Perdriolle Method was 200 for thoracic curves and 230 for lumbar curve. The longterm measurements were 100 and 10.30, respectively. It was not possible to measure vertebral rotation in all patients because of the superimposition of the rods. Emphasis is placed on surgical conditions and required instrumentation to achieve a good result. There were no neurological or infectious complications.

31 ARE THE MEYERDING CLASSIFICATION AND THE PERCENTAGE OF SLIPPING VALID AND RELIABLE METHODS IN EVALUATION OF LUMBOSACRAL SPONDYLOLISTHESIS? H. ElSaghir, H. Böhm Zentralklinik Bad Berka, Robert Koch Allee 9, 99437 Bad Berka Germany Introduction. The question of the validity and reliability of the Myerding classification and the % of slipping are pertinent not only when it comes to decision making before treatment of spondylolisthesis but also for the study of the natural history of the deformity and the evaluation of scientific longitudinal studies. Although the accurracy of the measurement methods has been questioned, there were no sufficient trials to introduce new methods for measurements or to correct the traditionally used ones. The aim of this study was to study the validity and the reliability of the Myerding classification and the % of slipping and to try to correct possible intrinsic errors of these measurements. Material and methods. 200 patients with spondylolisthesis at the L5-S1 level were subjected to radiological evaluation of their lumbar spine in the sagittal plane. According to Myerding classification 120 were grade 1 Myerding, 40 grade 2, 26 grade 3, and the remaining 14 cases were grade 4. The length of the lower end plate of L5 (x) and that of the upper end plate of S1(y) were measured and the dysplasia index x/y % was calculated. The anterior part of the L5 which covers S1(a) was also measued and the covering index a/x% was calculated. The % of slipping was measured using two different methods (Traillard et al. method and Poxal et al. Method). Results. The length of the opposing end plates of L5 and S1 were equal in 156 cases (78%). In 36 cases (18%), the upper end plate of S1 (y) was longer than lower end plate of L5 (x). In the remaining 6 cases (3%) y was shorter than x. The covering index a/x% referred to the surface area L5-S1 available for fusion. Significance of the results and conclusions. The Myerding Classification and the % of slippage are valid and reliable only when the AP diameter of L5 and S1 are equal. The covering index is more signicant than the % of slipping and can be very helpful when interbody fusion is considered in surgical planning.

32 CANINE STUDIES WITH A NEW SYNTHETIC CANCELLOUS BONE VOID FILLER E.M. Erbe, J.G. Marx, T.D. Clineff Orthovita, 45 Great Valley Parkway, Malvern, PA 19355 USA

Aim: To assess the biocompatibility, histologic integration, and resorption of Vitoss™ synthetic cancellous bone void filler (Orthovita, Malvern, PA), a new beta-tricalcium phosphate (TCP) scaffold. Vitoss, composed of nano-sized particles of beta-TCP, is 90% porous, providing more surface area than traditional calciumbased bone void fillers. Methods: Morsels (1 to 4 mm diameter) of Vitoss were placed into surgically created defects (10◊25 mm, staged 6 weeks apart) in proximal humeral metaphyses of 3 adult mongrel dogs. Dogs were euthanized 12 weeks after the first surgery, and the amount of remaining implant and new bone in the defect sites was quantified histomorphometrically. Results: Osteoid and new bone was observed in the centre of the defect by 6 weeks postimplant. Approximately 76%±10% of the implant material was resorbed by 6 weeks; 86%±4% was resorbed by 12 weeks (P<.05). The volume ratio of new bone within the defects to adjacent original bone was 0.6±0.4 at 6 weeks vs 1.2±0.5 at 12 weeks (P<.05). At 12 weeks, the amount of bone volume relative to unfilled space was not significantly different between new bone within the defects and adjacent original bone. Bone continued to mature at 12 weeks with no evidence of foreign-body response to the implant. Conclusion: When implanted in direct contact with bone, Vitoss scaffold expedites the growth of new host bone into the site. The scaffold is concurrently removed by cell-mediated and physical processes. Vitoss, which can be contoured to the shape of a defect, should prove useful for filling voids in non-load-bearing bones. 33 LUMBAR INTERBODY FUSION WITH OP1 VERSUS AUTOGRAFT IN A SHEEP MODEL E. Gay1, J.-P. Chirossel1, J.P. Boutrand2, P. Jenny, M. TurnerDomerguq3 1Department of Neurosurgery Grenoble, France; 2Biomatech Lyon, France; 3Stryker Spine, Bordeaux France A comparative study has been performed to investigate the efficacy, after six months, of Stryker PEEK(TM) and titanium cages packed with human recombinant osteogenic protein-1 (rhOP-1) or autograft to attain lumbar interbody fusion in a sheep model. Twenty mature sheep have been implanted with either PEEK(TM) or titanium cages filled with iliac crest autograft or rhOP-1 with carrier, in the lumbar spine. Four major groups of 5 sheeps were then defined. Two sheeps have been implanted with empty PEEK(TM) cages. Xrays were done monthly. A fluorescent bone labeling was performed at one month, two and 3 months. The animals were sacrified at 6 months. A CTscan of the lumbar region, an histology, an histo morphometry with bone density and implant/bone contact analysis, were then performed. Two animals were sacrified earlier due to non device related complications. A non fusion was observed for the two animals implanted with empty cages. For the other four groups, an histologically defined interbody fusion (bone tissue connection between the vertebral bodies through the cage) was obtained in 70% of the cases without any statistical difference between the groups. An excellent implant/bone contact area were obtained in each groups excluding the empty peek cages group. For the rhOP-1 groups, the fluorescent labeling analysis suggests an early bone formation with an intense remodeling. There were no negative effects on surrounding tissue (dura, muscle,..). This study confirms the interest of OP1 to achieve a good interbody lumbar fusion. OP-1 seems to stimulate an early important bone growth with an intense remodeling.

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34 IN-SITU LOCALIZATION OF MRNA AND PROTEIN OF FIBRONECTIN AND TGF-Β1 IN HUMAN INTERVERTEBRAL DISCS A.G. Gerlich, N. Boos Orthopaedic University Hospital Balgrist, Forchstrasse 340, CH8008 Zürich Objective: In reparative processes (e.g. wound healing) particularly the matrix constituent fibronectin is upregulated and assumed to play an important role. Furthermore, distinct cytokines are involved in these processes. Particularly, TGF-β plays a significant role in the induction of matrix constituents. So far, the role of fibronectin and TGF-β in the pathomechanism of disc degeneration has not been explored. Material: We therefore studied the tissue distribution of fibronectin and TGF-β1 in 20 surgically removed disc samples by immunohistochemistry (protein deposition) and non-radioactive in-situ hybridization (mRNA expression, i.e. neosynthesis) using specific polyclonal antibodies against the proteins and probes targeting specific gene segments of the respective genes. Results: All control experiments (blank and isotype controls in immunohistochemistry/sense controls in in-situ hybridization) revealed negative results. Immunohistochemically, we detected enhanced staining for fibronectin in both nuclear and anular tissues in those areas with histopathological signs of tissue degeneration (cleft formation and cell proliferation). The anular tissue was less severely altered and showed less interstitial fibronectin staining. The fibronectin-synthesizing cells were interspearsed mainly in the nuclear regions without obvious association to any anatomic structure. TGF-β1 synthesizing cells were seen both in nucleus and anulus which was consistent with the corresponding immunohistochemical protein localization. Conclusions: This preliminary study provides first evidence that tissue rearrangement during disc degeneration may be monitored by enhanced staining for fibronectin obviously produced by local cells. The concomittant localization of TGF-β1-synthesizing cells suggests stimulation of those local cells by auto- or paracrine pathways of disc matrix degradation. 35 IMMUNOHISTOCHEMICAL LOCALIZATION OF PHAGOCYTIC CELLS IN NORMAL AND DEGENERATIVE INTERVERTEBRAL DISCS A.G. Gerlich, C. Weiler, N. Boos Orthopaedic University Hospital Balgrist, Forchstrasse 340, CH8008 Zürich Objective: Knowledge on the function of disc cells is crucial if a biological enhancement of repair mechanisms is desired in order to find new treatment options for painful disc degeneration. The objective of this study is to explore the role of phagozytic cell activity in the process of disc matrix degradation by immunohistochemical labeling with a monoclonal antibody against a lysosomal protein (CD 68) which is specific for phagocytic cells. Methods: We investigated 42 decalcified complete sagittal sections through lumbar motion segments obtained from cadavers of various age (0–86 years) with varying disc degeneration and 55 surgical specimens from patients with disc herniation and degeneration. The antibody was visualied using either the avidin-biotin- or the APAAP-system. Results: Control experiments with non-immune serum showed negative results in all cases. CD 68-positive cells were detected in the nucleus of all individuals more than 18 years old, predominantly adjacent to tissue clefts. These CD-68 positive cells were morphologically not different from surrounding nuclear chondro-

cytes and were often arranged in clusters. In the anulus fibrosus only few CD-68 positive cells were seen, mostly in old-age individuals. In the vast majority of the surgical specimens, clusters of positive cells were seen in the nucleus pulposus, but also strongly in areas with vascular ingrowth. Conclusion: The findings of this study suggest that phagocytosis of matrix material may be due to recruitment of cells with macrophage phenotype. It appears that these cells are transformed local cells and are not invaded monocytes/macrophages. 36 “SCOLIOSIS ON THE INTERNET” C.T. Gibbons, V.R. Rapuri, S.L. Papastefanou Middlesborough General Hospital, Ayresome Green Lane, Middlesborough, TS5 5AZ, England Aim: To assess the quality of patient information regarding scoliosis on the World Wide Web. Background: Population access to the Internet is increasing rapidly. Wide dissemination of medical information is occurring along with an increase in patient expectations. Patients will often pre-empt their specialist consultation by accessing information by computer. Practitioners need to be aware of the quality of this information to maintain patient confidence and promote evidencebased education. Background: A broad based Internet search facility (“Copernic 2000”) was utilised allowing 11 search engines to be interrogated. The search parameter was “Scoliosis Patient Information”; performed on 07/03/00. Each site was visited and the information available was then analysed according to OMNI criteria (Organising Medical Networked Information). Results: Fifty-seven sites were returned by the search, representing 100 search engine results. Only two sites satisfied the applied OMNI criteria. 25% of the sites were commercially orientated towards a treatment modality. 44% of sites gave their last update; twelve of these were within one year prior to our search. Only one site gave an update policy. Conclusions: We have clearly demonstrated that the vast majority of information consists of overviews of the subject. Whilst this information is of value it is neither evidentially supported or sufficient to answer questions that a newly diagnosed sufferer may raise. There is scope for development of a non-commercial, scoliosis site. We would seek to provide information based on accepted or ongoing research. This information would be useful to patients and professionals alike. 37 DIAGNOSIS OF SPINE PATHOLOGY BASING ON BIOMECHANIC CHARACTERISTICS A. Gladkov Research Institute of Traumatology and Orthopaedics, Biomechanical Laboratory. Frunze str. 17, 630091, Novosibirsk, Russia Method of diagnosis of various spine deformities basing on quantitative characteristics of the form and plane orientation of the spine was developed. The co-ordinates of at least two points on each vertebral body are determined on 2 standard x-rays of a patient in standing position to receive the form and orientation characteristics of the spine which are used to calculate necessary angular and linear values with the help of a developed software and hardware complex “Automatic Work Place for a Spine Surgeon”. Composed combinations of quantitative signs peculiar to one or other type of the spine deformity form a reference for expert program to detect and formulate diagnosis. The program is based on the “lock-key” principle which permits to diagnose the deformities

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caused by idiopathic scoliosis, Scheuermann’s and Bekhterev’s diseases, congenital kyphosis, spondylolisthesis, lumbar osteochondrosis, and fractures and luxations of the vertebrae of different localization. Based on these data the classification of mentioned above deformities was developed having regard to the degree of their manifestation. The analysis of quantitative characteristics of the form and plane orientation of the spine allows to justify the form of treatment, length spinal fusion, degree of necessary correction of spine deformity and to estimate the results of treatment. Use of this technique for long-term follow-up of some patients permitted to determin the character and rate of progression of different types of spine deformities and to develop prognostic aspects of their development. 38 OPERATIVE CORRECTION AND STABILISATION OF NEUROMUSCULAR SCOLIOSIS: A CRITICAL ANALYSIS OF THE 2 YEAR RESULTS C. Götze, L. Hackenberg, U. Liljenqvist, H. Halm Klinik und Poliklinik für Allgemeine Orthopädie der, Westfälische Wilhelms-Universität Münster, Albert-Schweitzer-Strasse 33, 48149 Münster, Germany In order to evaluate the outcome of the operative treatment of neuromuscular scoliosis 52 patients were studied prospectively. Methods: 28 Patients were operated by posterior correction and fusion using the Münster Posterior Doublered-System (MPDS) (GI). 24 Patients were treated with one-stage ventro-dorsal procedure in combination of VDS with MPDS (GII). Five patients get operated by single anterior instrumentation. For all patients, medical and radiographic records were available, with a minimum follow-up of 2 years. Postoperative management, bloodloss and complications will be discussed. Results: In group I the preoperative average Cobb angle of main curve was 77.1°, with an average flexibility of 38.6%. The average postoperative Cobb angle was 34.1° (mean correction 55.9%) with an average loss of correction of 1.7°. In group II the mean major scoliosis measured 101.7°, with mean average flexibility of 25%. At most recent follow-up, the mean scoliosis magnitude was 42.2° (mean correction 58.5%). The mean angle of postoperative pelvic obliquity in group I was 3.6°, compared with 5.3° in group II, corrections of 53% and 73.5%, respectively. No significant loss of correction in follow-up. The average bloodloss in group I was 1800 ml and in group II 2600 ml. Conclusion: The data in the current study support the possibility in operative treatment of patients with severe neuromuscular scoliosis. The quality of life get improved by stability in seating and standing by correction of pelvic oblique and trunk instability. 39 CLINICAL RELEVANCE OF PYROPHOSPHATES AND NEOVASCULARISATION IN SPINAL DISCOGENIC PAIN A.K.D. Goswami, M.T.N. Knight, A.J. Freemont Spinal Foundation, Arbury Centre, Manchester Road, Rochdale OL11 4LZ, UK Introduction: Recent cadaveric studies have identified neovascularisation and neoneuralisation as probable mechanisms in the causation of discogenic pain. Calcium pyrophosphate deposits have been observed in discs in several studies. Their significance in the causation of discogenic pain is unclear. Aim and Objectives: The study aims to examine and correlate the presence of neovascularisation, crystalline pyrophosphate deposits in the disc and discogenic pain by spinal probing and discography under endoscopic visualisation.

Material and methods: Tissue removed from intervertebral discs of 224 patients during surgery were examined direct and polarised microscopy to identify the presence of calcium pyrophosphate and neovascularisation. Their presence were correlated to diagnostic provocative findings of spinal probing and discography and intradiscal distortion during aware state endoscopy. Results: Calcium Pyrophosphate: 20/224 (9%) patients demonstrated calcium pyrophosphate in the discs. 14 had pain reproduced on probing or discography. 13/20 (65%) of patients had either an annular collection or leak at the index level. 6 had an extradiscal cause of pain. 100% of these patients with annular collections or leaks had pain on spinal probing or discography. Neovascularisation: 37 out of 224 (16.5%) patients showed neovascularisation in the disc. 4 discs had crystalline pyrophosphate deposits. 33/37 (90%) had pain on probing and/or discography. Conclusion: The presence of pyrophosphate in the disc without a tear or leak does not directly render them tender to provocation. The presence of pyrophosphate is not correlated to neovascularisation. There is a high correlation between pain provocation and neovascularisation. 40 THE USE OF TRANSPEDICULAR DECANCELLATION OSTEOTOMY IN THE TREATMENT OF VARIOUS SPINAL DEFORMITIES O. Güven, M. Bezer, K. Gökkus Marmara University School Medicine, Department of Orthopedics and Traumatology, Istanbul, Turkey Purpose: Transpedicular decancellation osteotomy is used in the correction of various spinal deformities. The purpose of this study is to evaluate transpedicular decancellation osteotomy as the surgical treatment of patients with various spinal deformities. Materials and methods: Between 1990–1996, 23 consequtive patients with various spinal deformities were treated with transpedicular decancellation osteotomy. A retrospective chart and radiograph review was performed. Pre and Post-Operative radiographic measurement of regional and global kyphosis and lordosis, balance, apical kyphosis and lordosis was obtained. Patients were divided into three groups: Group 1. 4 patients with scoliosis. Group 2. 6 patients with epidural fibrosis secondary to discectomy or laminectomy. Group 3. 13 patients with kyphosis. Patients in this group were evaluated in five subgroupes, adult kyphosis (1 patient), congenital kyphosis (2 patients), sequela of Pott’s disease (3 patients), ankylosing spondylitis (4 patients), posttraumatic kyphosis (2 patients). Results: Average follow-up was 28 months, (Range, 24–50). This study group included 9 males and 14 females with an average age 41 yars old, (Range, 23–65).The treatment performed was posterior spinal decancellation osteotomy and posterior spinal fusion in all cases. In scoliosis group the average sagittal plane correction was 41 degrees. In kyphosis group the average correction was 45 degrees and in epidural fibrosis group it was 32 degrees. In epidural fibrosis group the primary aim was to relax streched dura, not to obtain maximal amount of sagittal plane correction. Discussion and conclusion: The patient with a fixed sagittal decompansated deformity or a streched dura due to epidural fibrosis presents a difficult orthopaedic challenge. Transpedicular decancellation osteotomy is an appropriate surgical treatment method for correction of fixed sagittal plane deformities and for relaxation of streched dura.

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41 EGG-SHELL TYPE DORSAL WEDGE OSTEOTOMY IN THE TREATMENT OF SYMPTOMS DUE TO PERIDURAL FIBROSIS IN PATIENTS WITH LUMBAR KYPHOSIS O. Güven, M. Bezer, K. Gökkus Marmara University School Medicine, Department of Orthopedics and Traumatology, Istanbul, Turkey Study design: Prospective case series. Objectives: To restore the physiological lordosis of the lumbar spine and to relax the tethered dura due to fibrosis. Summary of background data: Peridural fibrosis is one of the most important complications of lumbar spine surgery. After disc surgery 12 to 15% of the patients complain about chronic low back pain. We think that peridural fibrosis and lumbar kyphosis together make a tethering effect on dura and cause intractable symptoms. Methods: We performed egg-shell type dorsal wedge osteotomy in 8 patients with severe back and leg pain. 6 patients with sufficient follow up time were evaluated. Before the treatment all patients had undergone multiple spinal operations. Peridural fibrosis was reported in previous operations of patients. All patients had excision of fibrosis and different types of conservative treatment. Patients were resistant to these treatment methods. In the operation transpedicular decancellation of the vertebral body was done just above segment of epidural fibrosis. Dorsal elements of the vertebral body were excised, then upper and lower vertebral segments compressed to each other by the help of transpedicular screws and hooks. Lumbar lordosis is restored peroperatively. During the compression, relaxation of the dura was also observed. Results: Lumbar dorsal wedge osteotomy was performed with a mean of 38 degrees (range: 16–44 degrees) kyphotic deformity. Mean correction was 32 degrees (range: 26–34 degrees) closing After mean 31 months of (24–50 months) follow-up there was significant change in kyphosis angle and there was no recurrence of symptoms. The overall pain and function improved in all patients, and all were satisfied with the results. Conclusion: Egg-shell type posterior wedge osteotomy is useful in the treatment of pain and functional loss due to peridural fibrosis in patients with lumbar kyphosis. 42 TUBERCULOSIS OF THE LUMBOSACRAL REGION. LONG-TERM FOLLOW-UP OF PATIENTS TREATED BY CHEMOTHERAPY, TRANSPEDICULAR DRAINAGE, POSTERIOR INSTRUMENTATION AND FUSION O. Güven, M. Bezer, K. Gökkus, S. Yalcin Marmara University School Medicine, Department of Orthopedics and Traumatology, Istanbul, Turkey Purpose of study: To prove the hypothesis that transpedicular drainage and single stage posterior instrumentation-fusion is enough for the prevention of lumbar kyphosis in selected cases. Materials and Methods: Of a total of 55 patients with the diagnosis of spinal tuberculosis, 3 patients had involvement of lumbosacral region. Follow-up period was averaged 63 months (range: 36–97 months). There were 2 male and 1 female and average age was 58 years (range 34–74 years). The following data were studied in these patients: most commonly involved vertebra, vertebral body loss, progress of the angle of kyphosis. Results: The fourth lumbar vertebra was the most common vertebral segment involved, and the lumbosacral junction was affected in all 3 patients. The average preoperative kyphosis was 15.3 degrees and decreased to 4.3 degrees postoperatively. Change in kyphotic angle was not significant at last follow-up. There was no recurrence of infection.

Discussion: In tuberculosis of the lumbosacral region, anterior debridement and fusion with a strut graft can reduce the incidence and size of kyphosis, but is technically demanding. In young patients continued growth of posterior parts of the vertebrae is an additional factor for progressive kyphosis formation. Posterior fusion and instrumentation also prevents this growth resulting in progressive kyhosis. Conclusion: It is considered that transpedicular drainage and posterior instrumentation-fusion is a less demanding operative technique for lumbosacral tuberculosis for the prevention of lumbar kyphosis in selected cases. 43 ANALYSIS OF THREEDIMENSIONAL CORRECTION AFTER ANTERIOER SCOLIOSIS SURGERY BY DIGITISED RADIOGRAPHS AND RASTERSTEREOGRAPHIC BACKSHAPE MEASUREMENT IN IDIOPATHIC SCOLIOSIS L. Hackenberg, U. Liljenyvist, E. Hierzolzer, H. Halm Klinik und Poliklinik für Allgemeine Orthopädie, Albert-Schweitzer-Strasse 33, 48149 Münster, Germany Introduction: Analysing the obtained derotation of spinal deformities after anterior surgery can be difficult, when implants cover the essential radiographic landmarks. Additionally derotation of the apical vertebrae cannot be directly compared to surface derotation. To determine the postoperative correction accurately, radiographs were digitised and back surface was analysed by videorasterstereography. Methods: 31 patients with idiopathic scoliosis (thoracic, thoracolumbar and lumbar curves), who underwent VDS-Zielke or Halm-Zielke instrumentation (average age 17.7 [13–26]) were pre, postoperatively and at follow-up (37,6 months [23–78]) examined with rasterstereography in standing posture. The a. p. radiographs were digitised according to the method of Drerup, which enables postoperatively an accurate determination of vertebral derotation by interpolation. Radiographic and backshape data were compared. Results: The Cobb angle of the primary curve was reduced from 57.2° (38–88°) to 17.2° (3–34°), of the secondary curve from 34.5° (16–48°) to 21.5°(7–48°). Vertebral rotation of the primary curve decreased from 18.6° (9–41°) to 9.2° (2–18°), of the secondary curve from 7.6° (2–18°) to 5.8° (2–18°). Maximum surface rotation decreased from 16.5 to 10.8° with loss of correction of 5% after follow-up. In six cases of rigid secondary curves surface rotation postoperatively increased in thoracic area. Conclusions: A frontal curve correction of 70% on average is comparable to other author’s results. The derotation of the apical vertebrae of the primary curve was 51%. Surface derotation was significantly less than vertebral derotation (34%) in particular at follow-up. In cases of rigid thoracic secondary curves surface rotation can increase and cosmetic improvement can be limited. 44 BIOMECHANICAL COMPARISON OF FIVE DIFFERENT ATLANTO-AXIAL FIXATION TECHNIQUES T.P. Henriques, B.W. Cunningham, C. Olerud, N. Shimamoto, P.A. McAfee Uppsala University Hospital and The Union Memorial Hospital and the Scoliosis and Spine Center, St. Josephs Hospital, Baltimore, Maryland, USA Introduction: Previous investigations have demonstrated that three-point fixation using bilateral transarticular screws in combination with posterior wiring, provide the most effective resistance to minimize motion about C1-C2. The primary objective of the

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present study was to determine whether non-bone graft dependent one-point fixation can afford stability levels equal to three-point reconstruction. Methods: Eight human cervical specimens (C0-C4)(age range 70–94 yrs., mean 78,1) were utilized in the current study. Non destructive biomechanical testing was performed, including axial rotation(+-1,5Nm, 50 N preload), flexion/extension (+-1,5Nm) and lateral bending (+-1,5Nm) loading modes. Following intact spine analysis, each speciman was reconstructed using five different fixation techniques. Results: Under axial rotation all C1-C2 reconstructions indicated significantly higher stiffness levels than the intact spine (p< 0.0001.) The two and three-point reconstructions using transarticular screws provided higher stiffness than the one-point reconstructions (p<0.05.) During flexion/extension, higher stiffness levels were observed in one and threre-point fixations when compared to intact spine at p<0.05. Conclusion: Three-point reconstructions using bilateral transarticular screws in combination with posterior wiring or the new C1 claw device, proved to markedly reduce motion in all planes compared to one and two-point fixations. The one point fixation constructs used in this study which do not rely on satructural bone graft, resulted in less stability compared to the three-point reconstructions.The current study substantiates the use of three-point fixation as the treatment of choice for C1-C2 instability. When used in combination with transarticular screws, the new C1 claw device provides an alternative to posterior wiring reconstructions. 45 RECURRENT LUMBAR DISC HERNIATION – DORSAL REOPERATION OR VENTRAL INTERBODY FUSION WITH CAGES (BAK)? J.F. Huber1, E. Cesnulis2, A. Kalbarczyk3, H. Landolt3, G. Ruflin1 1Clinic of Orthopaedic Surgery; 2Clinic of Neurosurgery Kantonsspital Aarau, Switzerland; 3Clinic of Neurosurgery, University Vilnius, Lithuania Idea/aim: The ventral interbody fusion with cages provides us with the possibility to remove protruded disc material ventral to the longitudinal ligament. We compared the conventional technique of refenestration and revision with the ventral interbody fusion (BAK Cages) fin case of symptomatic recurrent lumbar disc herniation. Method/patients: The study was designed as prospective case control study and performed by an independent reviewer (CE). The patients were evaluated with the NASS questionnaire, clinically and radiologically. Totally 51 patients were operated due to the recurrent symptomatic lumbar disc herniation during the period of 1998–1999. 12 patients were treated with interbody fusion (Cohort A) and we selected 20 patients with refenestration and revision (Cohort B), matched regarding age, sex, body mass index and symptomatic level. Average follow up was 11 months (6–19 months). In each cohort one patient was lost in the follow up (reemigration). Results: Backpain (1–6) A preop 5,8, postop 2,4; B preop 5,6, postop 3,3. Legpain (1–6) A preop 5,6 postop 1,3; B preop 5,8, postop 2,1. Tingling, paresthesia (1–6) A preop 5,7, postop 1,2; B preop 5,8 postop 2,3. Personal independence (1–6) A preop 5,1, postop 1,4; B preop 5,5, postop 2,1. Patient satisfaction was higher in cohort A versus B. There were no major surgical complications in both cohorts. We had two cases of repeated recurrency in cohort B. Conclusion: The technique of ventral disc exploration and removal of disc material in case of recurrent disc herniation is a valid procedure. Interbody fusion with cages without dorsal stabilisation can be performed. Further studies and long-term results are necessary.

46 THE SIGNIFICANCE OF BACK PAIN HISTORY IN DETERMINING DIAGNOSIS A.R. Humphrey, A. Hutchings, C.G. Greenough Middlesbrough General Hospital, Ayresome Green Lane, Middlesbrough, Cleveland. TS5 5AZ UK Introduction: The predictive values of individual facet of the clinical history has not been systematically investigated previously but may be important for the development of computer assisted diagnostic aids. Methods: 465 patients attending a spinal clinic were studied. Patients completed 42 questions concerning there symptoms which allowed only yes/no answers. Patients were allocated to one of nine diagnostic categories by an experienced surgeon without reference to the questionnaire. The association of individual symptoms with each diagnostic category was examined. Results: “Mechanical back pain” (n=322) was significantly associated with “leg pain the same as back pain”, “back suddenly goes” and “pain lasts for 15 minutes or more following exercise” and negatively associated with “leg pain”, “parasthaesia” and “coughing/sneezing aggravates the pain.” No question could discriminate mechanical subjects from others with an accuracy of greater than 0.76. “Disc prolapse” (n=52) was significantly associated with “leg pain the worse than back pain”, “back pain worse than leg pain when walking”, “pain lasts for less than two minutes following exercise” and “coughing causes pain in the legs” and “leg pain causes you to stop”. None discriminate these subjects with an accuracy greater than 0.7. “Stenosis” (n=43) was significantly associated with “back worse than legs when walking”? “leg pain force you to stop” and “pins and needles when walking.” It was negatively associated with “back ‘goes’ suddenly”? None discriminate these subjects with an accuracy greater than 0.64. “Tumor/infection” (n=7) was significantly associated with “past history of cancer” and negatively associated with “sitting causes back pain.” Both discriminate these subjects with an of 0.76. Similar associations for were found for “Central Disc” (n=7) and “Nerve Root Compression” (n=31). The categories “caudea equina”, “inflammatory stiffness” and “arterial claudication.” Contained only one subject each. Conclusions: Only a limited subset of the questions commonly asked during history taking were significantly associated with the diagnosis. The accuracy of diagnosis was insufficient for clinical purposes. This implies that the clinician is weighting the data in a manner not yet completely described. Further development is underway to investigate computer assisted diagnostics. 47 BRACE TREATMENT FOR SCOLIOSIS IN 0I, (IM)POSSIBILITIES P.J. Huystee, R.J.B. Sakkers, H.E.H. Pruijs UMC,KE 04.140.5, Postbus 85090, 3508 AB Utrecht, The Netherlands Purpose. The evaluation of softcast brace treatment for scoliosis in OI. Patients and methods. Out of 110 patients with OI, 24 patients with beginning or established spinal deformities, scoliosis, kyfosis or/and biconcave vertebra, were treated with soft cast braces, individually made using traction in the sitting position. The braces were worn at day time only. In every patient their brace was replaced by a new brace every 4–6 months.Compliance, patient satisfaction and Cobb angles were recorded in time. Results. In a consecutive serie, 24 children were treated and followed. The data are listed in Table 1.

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OI- N type

m/f

Age

fu (years)

Cobb at start

Cobb at last fu

I 4 III 11 IV 9

0/4 4/7 5/4

9.2 (8.6–10.3) 8.0 (3.9–11.7) 7.5 (3.1–12.8)

2.7 (1.8–4.3) 0 (0– 0) 5 (0– 20) 2.9 (0.5–3.6) 37.6 (0–66) 41 (0– 69) 2.4 (0.5–5.0) 18.6 (0–61) 38.1 (0–124)

(N=number; m/f=male/female; fu=follow-up

In 5 children a decrease of Cobb angle was seen, in 9 a stabilization occurred and in 10 patients the scoliosis progressed. Patients with a benefit from brace treatment showed a Cobb angle at start of less than 30 degrees and an age below 9 years. Definitive failure of treatment was seen in 6 children. They were treated operatively. Compliance was good in 17, not classified in 3 and not good in 4 patients. Subjective patients satisfaction was noted in 17 children. Discussion. Conventional brace treatment for scoliosis is not possible in OI, due to the fragility of the bone (ribs). It causes more pain and fractures and no benefit is realized. Patients suffering from osteoporosis, can be treated with soft braces to comfort their spinal pain. Also in children with secondary osteoporosis this treatment is successfull. Therefore, we started with softcast treatment in patients with OI that were complaining of spinal pain at the end of the day. The major advantage was pain releave and sitting comfort. However, to our surprise, it seemed that in some children a decrease in scoliosis progression was seen. This effect was especially noted in the early onset of treatment in patients with a Cobb angle less than 30 degrees. Due to the satisfaction of these patients, we have started protocollar soft cast treatment for spinal problems in children with OI. Children with severe scoliosis entering pubertal growth seem not be suitable for this kind of treatment.The final outcome of this treatment in patients with OI still has to be established. 48 CLOSING WEDGE VERTEBRAL OSTEOTOMY FOR CORRECTION OF LUMBAR KYPHOSCOLIOIS M. Ikenaga, J. Shikata, C. Tanaka, M. Takahashi, K. Mihara Department of Orthopedic Surgery, Kyoto City Hospital, 6048845 Kyoto, Japan Introduction: Degenerative lumbar kyphosis often causes severe low back pain, sciatica or cauda equina syndrome. Retaining total spinal balance by correction of kyphotic deformity is a key to improve these symptoms. We have performed 11 cases of posterior closing wedge osteotomy for correction of lumbar kyphosis. The study reports retrospective evaluation of the clinical results. Patients and methods: The age of patient was from 21 to 75 (mean 60.1). Congenital kyphosis for one case, and degenerative kyphoscoliosis for 10 cases. After laminectomy and resection of pedicles, wedge osteotomy was done, and was fixed with pedicle screws after correction. Local bone chips with HA granules were grafted posterolaterally. Results: Mean operation time was 4h24m, mean blood loss was 1584 g. Preoperative kyphosis of 16 degrees improved to 11 degrees of lordosis postoperatively. Low back pain score improved 17/29 to 21/29 points. There were no severe neurological deficits. Discussion: Few reports can be seen concerning correction osteotomy for degenerative lumbar kyphoscoliosis, although many authors reported for ankylosing spondylitis.Degenerative lumbar kyphoscoliosis is often treated with PLIF. Multiple level PLIF, however, is necessary for achieving an ideal correction, since the correction angle for one level is limited. Multiple PLIF causes prolonged operation time, increased blood loss, increasedpossibility of infection. Ideal correction can be achieved more simply by sin-

gle level of osteotomy, because the mean correction angle was as much as 26 degrees. Conclusion: The study showed that correction of degenerative lumbar kyphoscoliosis could be achieved safely and effectively using closing wedge osteotomy technique. 49 ANTERIOR SURGERY FOR THE THORACIC SCOLIOSIS A. Kanazawa, K. Yonenobu, I. Sato, M. Horiki, H. Yoshikawa Department of Specific Organ Regulation, Graduate School of Medicine, Osaka University, Japan Purpose: Anterior correction and fusion has been the treatment of choice for the thoracolumbar and lumbar scoliosis. Recently, indication of this procedure has been extended to the thoracic scoliosis, with development of anterior spinal instrumentation system for the thoracic and lumbar spine. Advantages of anterior surgery for the thoracic scoliosis are better correction for rotational deformity, less extensive fusion levels, and a safer correction by spinal shortening. We have treated patients with the thoracic scoliosis by anterior correction and fusion using an instrumentation system devised by Dr. Kaneda. The purpose of this study is to evaluate the surgical results of this procedure. Patients: This is a prospective study of consecutive 8 patients who underwent anterior correction and fusion for the idiopathic thoracic scoliosis. There were 2 males and 6 females, the average age at operation was 14.7 years. The average follow-up period was 24 months. All patients had a major thoracic curve in their coronal curvatures, and there were 7 with type I ;and 1 with type II; according to the classification of King et al. Methods: With respect to the determination of the extent of the fusion, the only segments not to be corrected by preoperative lateral bending were fused. The operation was usually performed through thoracotomy after the resection of an appropriate rib. Instrumentation followed by the discectomies of the fusion segments was performed. Serial radiographic evaluations were performed using the standing posteroanterior and lateral radiographs preoperatively, postoperatively, and at final follow-up. Coronal curvature of the major curve (Cm) and that of the instrumented levels (Ci) were measured by means of Cobb method. Rotational deformity of the apical vertebra(Ra) measured by Aaro and Dahlborn method was assessed. The tilting angle of the upper and lower end vertebrae (Tup., Tlo.) against the horizontal line was also measured to determine the spontaneous correction over them. Results: According to the evaluation of preoperative lateral bending radiographs, no patients fused to the extent of both end vertebrae. The average number of fused segments was 4. The average preoperative Cm, Ci and Ra were 63.1°,50.2°and 21.7°. The postoperative Cm, Ci and Ra were 36.0°, 23.7°and 12.7°on the average. The average correction rates of Cm, Ci, and Ra were 43.2%, 53.8%, and 42.9% postoperatively. At the final follow-up, correction loss of Cm was 5.7°, and that of Ci was 3.3°on the average. In terms of Tup. and Tlo., correction loss was only seen at the upper end vertebrae by 5.6°on the average. There was neither pseudoarthrosis developed, nor instrumentation failure. No patients suffered from neurological deficits after surgeries. Conclusions: Several authors reported good surgical outcomes of anterior procedure for thoracic scoliosis. In almost all of them, fusion extended to both end vertebrae. In this study, however, correction over the instrumented levels and derotation of the apical vertebrae were accepted even though both end vertebrae were not included in fusion. As a matter of fact, correction of the whole curve was not as good as previous reports. Furthermore, correction loss occurred at the segment of upper end vertebra. To obtain the better correction and avoid the correction loss during the followup, it is suggested that upper end vertebrae should be included in the fusion.

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BIODEGRADABLE POLY-(D,L)-LACTIDE COATING OF A CERVICAL SPINE INTERBODY FUSION CAGE. RADIOGRAPHIC AND BIOMECHANICAL IN VIVO RESULTS OF A NEW CARRIER FOR GROWTH FACTORS F. Kandziora, G. Schmidmaier, R. Schröder, G. Duda, M. Raschk M, N.P. Haas, T. Mittlmeier Unfall- und Wiederherstellungschirurgie, Universitätsklinikum Charité der Humboldt Universität Berlin, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353 Berlin, Germany

TGF-Β AND IGF-I APPLICATION BY A POLY-(D,L)-LACTIDE COATED INTERBODY CAGE PROMOTES FUSION IN THE SHEEP CERVICAL SPINE. RADIOGRAPHIC AND BIOMECHANICAL RESULTS F. Kandziora, G. Schmidmaier, R. Schröder, G. Duda, M. Raschke, N.P. Haas, T. Mittlmeier Unfall- und Wiederherstellungschirurgie, Universitätsklinikum Charité der Humboldt Universität Berlin, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353 Berlin, Germany

Introduction: Experimentally, growth factors such as BMP-2 have proven to promote spine fusion and to overcome the disadvantages of an autologous bone graft. The optimum method to deliver such growth factors is still a matter of discussion. Especially collagen sponge carrier are in use. Yet, safety and accuracy of these carriers are questionable. The purpose of this study was to evaluate the effect of a biodegradable poly-(D,L)-lactide (PDLLA) carrier system in a in vivo sheep cervical spine interbody fusion model. Background: 16 adult female merino sheeps underwent C3/4 discectomy and fusion using either a meshed titanium cage alone (group 1; n=8) or a meshed titanium cage coated with a biodegradable poly-(D,L)-lactide (PDLLA) carrier (group 2; n=8). Digital radiographic scans were performed pre- and postoperatively and after 1, 2, 4, 8, 12 weeks. Intervertebral disc space height (DSH), intervertebral angle (IVA) and lordosis angle (LA) were measured. After 12 weeks fusion sites were evaluated using digital functional radiographic views in flexion and extension. Quantitative computed tomographic scans (QCT) were performed to asses bone mineral density (BMD), bone mineral content (BMC) and callus volume (CV). Biomechanical testing was performed in flexion, extension, axial rotation and lateral bending with a non-destructive stiffness method. Results: Over a 12 week period no differences were found for radiographic evaluation of DSH, IVA, and LA. Functional radiographic assessment revealed no differences between the two groups. After 12 weeks the PDLLA coated cages showed constantly higher values for BMC (group1: 3.0 g; group 2: 3.31 g; p=0.09), CV (group 1: 1.7 cm3; group 2: 2.03 cm3; p=0.21) and BMD at the endplates (see figure 1). Average stiffness in flexion/extension (group1: 4.59 Nm/degree; group 2: 5.72 Nm/degree; p=0.45), rotation (group 1: 6.73 Nm/degree; group 2: 6.29 Nm/degree; p=0.64) and bending (group1: 5.72 Nm/degree; group 2: 5.83 Nm/degree; p=0.87) showed no significant difference between the two groups.

Introduction: Spinal fusion using autologous bone graft is associated with donor site morbidity and a non-union rate up to 35%. Experimentally, growth factors such as BMP-2 have proven to promote spine fusion and to overcome the disadvantages of a autologous bone graft. The optimum growth factor to promote spinal fusion is still a matter of discussion. The purpose of this study was to evaluate the efficacy of transforming growth factor-β (TGF-β) and insulin-like growth factor-I (IGF-I) application by a poly-(D,L)lactide (PDLLA) coated cage in a in vivo sheep cervical spine interbody fusion model. Background: 16 adult female merino sheeps underwent C3/4 discectomy and fusion using either a iliac crest bone graft (group 1; n=8) or a meshed titanium cage coated with a biodegradable PDLLA carrier (group 2; n=8) including TGF-β (1% w/w) and IGF-I (5% w/w). Digital radiographic scans were performed preand postoperatively and at 1, 2, 4, 8, 12 weeks. Intervertebral disc space height (DSH), intervertebral angle (IVA) and lordosis angle (LA) were measured. After 12 weeks fusion sites were evaluated using digital functional radiographic views in flexion and extension. Quantitative computed tomographic scans (QCT) were performed to asses bone mineral density (BMD), bone mineral content (BMC) and callus volume (CV). Biomechanical testing was performed in flexion, extension, axial rotation and lateral bending with a non-destructive stiffness method.

0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0

g/cm³ native Cage Cage + PDLLA

C3 UE

C3 M

C3 LE

callus

C4 UE

C4 M

C4 LE

A

B

C

D

Fig. 1 BMD of the upper endplate (UE), middle of the vertebra (M), lower endplate (LE) and callus at C3 and C4 for both groups (native data obtained by pilot studies)

Conclusion: PDLLA-coating of cervical spine interbody fusion cages as a delivery system for growth factors showed no adverse effects on cervical spine interbody fusion. The positive effect of the PDLLA-coating on BMD, BMC and CV might be a result of degradation process of the biodegradable carrier.

Fig. 1 A Lateral X-ray of a iliac crest graft 12 weeks postoperatively; B lateral X-ray of a PDLLA coated cage with TGF-β and IGF-I 12 weeks postoperatively; C axial computed tomographic scan of a iliac crest graft 12 weeks postoperatively; D axial computed tomographic scan of a PDLLA coated cage with TGF-β and IGF-I 12 weeks postoperatively

Results: Over a 12 week period IVA and LA showed significant higher values for group 2. Functional radiographic assessment revealed significant lower residual flexion/extension movement for group 2 (group1: 12.0 degrees; group 2: 6.75 degrees ; p <0.05). After 12 weeks (figure 1) the PDLLA coated cages with TGF-β and IGF-I showed significant higher values for BMD (group1: 0.585 g/cm3; group 2: 0.647 g/cm3; p <0.05), BMC (group1: 4.0 g; group 2: 5.15 g, p <0.05) and CV (group1: 2.1 cm3; group 2: 3.33 cm; p <0.05). Average stiffness in rotation was significantly

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higher in group 2 (group1: 6.21 Nm/degree; group 2: 9.76 Nm/degree; p=0.64). Conclusion: In comparison to the iliac crest graft, TGF-β and IGF-I application by a PDLLA coated interbody cage significantly accelerates interbody fusion in the sheep cervical spine. 52 PSEUDOARTHROSIS AFTER ANTERIOR BONE GRAFT FOR PYOGENIC SPONDYLITIS WAS HEALED BY POSTERIOR INSTRUMENTATION SURGERY: A CASE REPORT I. Kato, S. Akagi, T. Saito, K. Sasai, Y. Nakahigashi Dept. of Orthopedic Surgery, Kansai Medical University, 10–15 Fumizono-cho, Moriguchi, Osaka, Japan A 66-year-old man presented with a 6-month history of severe back pain after sepsis according to intestinal ileus. Roentogenogram showed destruction of the Th9/10 disc, and MRI showed an abscess in the Th9 intra-vertebral body. Transpedicular biopsy was performed, and Candida albrata was cultured. Investigation included a full blood count, which was normal except for an erythrocyte sedimentation rate (ESR) of 32 mm and CRP of 1.69 mg/dl. No neurological abnormality was examined. Conservative treatment was selected, so Fluconazole (100 mg/day) was intravenously injected and Itraconazole (150 mg/day) was administered for 12-weeks. However, severe back pain and elevated CRP were continuous. Anterior debridement and autologous bone graft were performed. Post-operatively medication was continued for 6months again, but elevated ESR,CRP and severe back pain were continuous and furthermore, local kyphotic deformity at Th9/10 level was deteriorated. Additional operation using posterior instrumentation, which transverse hook and pedicle screw were located from Th7,8 to Th12, L1 without infected vertebral body, was performed. After second operation, medication was continued vigourously with intravenous Fluconazole (400 mg/day) for 10week. 10-months later ESR and CRP were normalized, and 15months later roentogenographic tomograph showed a bony union. This case shows the significance of spinal stabilization for treatment of infectious spine.

mediate postoperative and final follow-up sagittal angles were –4.8, -14.3, and –11.7, respectively. There was a mean reduction of 9.6 (range from 5 to 14) after surgery. Three patients had a correction loss more than 3 during follow-up period. Bony fusion was obtained in all patients. There was no recurrence of the disease. Our results show that this strategy provides satisfactory stabilization and prevents development of late kyphosis in patients with tuberculosis of the lower lumbar spine. 54 RESULT OF PEDICLE SUBTRACTION EXTENSION OSTEOTOMY OF THE KYPHOTIC DEFORMITY IN ANKYLOSING SPONDYLITIS K.T. Kim1, J.S. Ahn2 1Dept. of Orthopaedic Surgery, Kyung Hee University, Seoul, Korea; 2Dept. of Orthopedic Surgery. Chung Nam National University, Korea Purpose: The purpose of study is to verify radiographic and clinical results of theextension osteotomy through pedicular subtraction and intracorporal decancellizationin ankylosing spondylitis patients who have severe deformity of fixed kyphosis. Method & operative Background: The osteotomy was performed at single level in 43cases, double levels in 2 cases. The mean follow-up was 36.2 months. After exposureof correction level through posterior midline approach and insertion of the pediclescrews, pedicular subtraction and intracorporal decancellization were performed withcuret and punch forceps. The correction was achieved by gradual extending theoperation table. Radiographic assessment for sagittal balance and clinical assessmentwere changed on preoperative, postoperative 3 months and the last follow-up asflollows; thoracic kyphosis: 50, 51, 53 degrees, lumbar lordosis: 10, 46, 44 degrees,distance between vertical lines of T1 and S1: 94, 15, 16 mm, sacral inclination: 8, 28,24 degrees. At the last follow-up, clinical results were high as 3.2/4.0 in function, 2.8 in indoor activity, 3.3 in outdoor activity, 3.3 in psychosocial activity and 3.4 in pain. Conclusion: Our osteotomy is relatively safe. Eighty five percent of patients haverevealed self-satisfaction. But in connection with the clinical results, the changes ofparameters of radiographic assessment should be traced much longer.

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POSTERIOR INSTRUMENTATION USING COMPRESSIVE LAMINAR HOOKS AND ANTERIOR INTERBODY FUSION FOR TREATMENT OF THE TUBERCULOSIS OF LOWER LUMBAR SPINE D.J. Kim, K.J. Roh, J.K. Oh, J.M. Wang Department of Orthopaedic Surgery, College of Medicine, Ewha Womans University, Seoul, Korea

CERVICAL PERCUTANEOUS LASER DISC DECOMPRESSION: RESULTS OF A PROSPECTIVE OUTCOME STUDY M.T.N. Knight, A. Goswami, J.T. Patko The Spinal Foundation, Arbury Consulting Centre, Manchester Road, Rochdale OL11 4LX, UK

A common problem in patients with tuberculosis of the lower lumbar spine is the back pain. It has been reported that patients ended up with a kyphosis had a higher incidence of back pain. The purpose of this study is to evaluate the efficacy of a surgical strategy consisting of posterior instrumentation with compressive laminar hooks and anterior interbody fusion for the tuberculosis of the lower lumbar spine. All patients at the authors’ institution having this procedure were reviewed retrospectively. Clinical outcomes were subjectively graded at final assessment. Sagittal angle and fusion status were evaluated by the last follow-up roentgenograms. Nineteen patients with tuberculosis of the lower lumbar spine were included in this study. The group consisted of seven men and twelve women with a mean age of 47 years (range, 27–58 years). The levels of involvement were L3–4 in seven patients, L4–5 in ten, and L2–3 and L3–4 in two. The mean follow-up period was 28.6 months (range, 24–39 months). The average preoperative, im-

Objectives: This prospective study was designed to identify the clinical response to Holmium-YAG2100 nm or KTP532 nm Percutaneous Cervical Laser Disc Decompression performed as a day case procedure in patients with soft cervical disc protrusion. Material and methods: With confirmation of the site and the affected disc area, KTP or Holmium laser disc decompression was effected at the index levels. Long term results were assessed using the Modified Vernon & Mior Neck Disability Index(VMDI), visual analogue pain (VAP) scores, patient satisfaction rating and Patient Target Achievement Scores. Results: Between 1992 and 1998, 105 patients underwent spinal probing and discography at 235 levels for a painful neck condition with or without brachialgia. 54 levels were treated with HolmiumYAG2100 nm and 51 levels with KTP532 nm laser disc decompression. Patients were followed for 1–7 years (mean: 3.1years). With KTP Laser Disc Decompression good to excellent results

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(VMDI) for neck, shoulder and arm was obtained in 48%,43%, and 52% patients respectively while another 24%, 37% and 24% obtained satisfactory results respectively. The corresponding figures for Holmium Laser Disc Decompression was 53%, 33%, 53% good or excellent results and 25%, 32% and 31% satisfactory results. There was no difference observed between the patients treated with KTP or Holmium Laser Disc Decompression. Conclusions: Daycase Percutaneous Laser Disc Decompression is a safe alternative to open cervical discectomy with satisfactory outcome for the patients with soft disc herniation. These laser techniques ablate inflammatory disc tissue and anneal the annulus achieving promising results in patients with neck pain and brachialgia.

56 ENDOSCOPIC FORAMINOPLASTY: A PROSPECTIVE STUDY ON 250 CONSECUTIVE PATIENTS WITH INDEPENDENT EVALUATION M.T.N. Knight1, A. Goswami1, J.T. Patko1, N. Buxton2 1The Spinal Foundation, Manchester Road, Rochdale OL11 4LX; UK; 1Dept. of Neurosurgery,University Hospital, Nottingham, UK Objectives. The objective has been to assess the efficacy of endoscopic aware state pain source definition using the system of “viviprudence” combined with endoscopic decompression of the foramen, mobilisation and neurolysis of the exiting and transiting nerves and ablation of osteophytes and other causes of the ‘failed back syndrome’ guided by patient feedback. Methods. This prospective study involved “daycase” Endoscopic Laser Foraminoplasty performed on 121 males, and 129 females with an average age of 48 years (22–86 years). They were followed for an average period of 30 months (26–43 months). 75 Patients had had 1 – 3 previous open operations. Results. 97% cohort integrity was maintained at the final follow up. Clinical assessment were compared and analysed using the percentage change in Oswestry Disability Index, and percentage change in visual analogue pain (VAP) scores, a Patient Satisfaction Scoring Scale and a patient Target Achievement Score. Clinically appreciable change was observed in 74% patients with back pain, 77% buttock pain, and 75% leg pain. Using a percentage change in Oswestry Disability Index of 50 or more to determine good and excellent outcomes, 61% of patients exceeded this score for back pain; 66% for buttock pain; and 65% for leg pain. 94% patients required no further surgical intervention. Conclusion. These results indicate that Endoscopic Laser Foraminoplasty provides a minimalist means of exploring the extraforaminal zone, the foramen and the epidural space. It provides a promising means of identifying and treating the pain of ‘failed back surgery’ and back pain and sciatica of indeterminate origin.

57 EFFECTS OF THORACOLUMBOSACRAL ORTHOSIS (TLSO) ON SPINAL DEFORMITIES, TRUNK ASYMMETRY AND FRONTAL LOWER RIB CAGE IN ADOLESCENT IDIOPATHIC SCOLIOSIS P. Korovessis, A. Baikousis, G. Petsinis, Z. Papazisis Orthopaedic Department General Hospital “Agios Andreas” 1 Tsertidou str. 26224 Patras, Greece Objectives. Prospective study to document immediate and late changes in shape and balance of the thoracic and lumbar spine and lower rib cage on the frontal plane induced by TLSO treatment for idiopathic adolescent scoliosis. Methods. In this prospective study twenty-four healthy female adolescents with major thoracic and/or lumbar scoliosis averaging

30o and 26o respectively, were treated with full time TLSO program. Several roentgenographic parameters (scoliosis, kyphosis, convex and concave rib-vertebral angles T7 to T12, frontal trunk balance, frontal vertebral inclination, rotation and translation T7 to L4-vertebrae) were measured before bracing, one month after bracing and thereafter once biannually in brace and without brace for a four-year period. All patients were roentgenographically reevaluated at the age of 20 years, at an average of 3.5 years after termination of bracing to measure any permanent changes of the above mentioned roentgenographic parameters. Results. TLSO treatment corrected both thoracic and lumbar scoliosis and reduced lateral trunk shift at the expense of significant although temporarily reduction of physiological thoracic kyphosis (<20 degrees), increase of lateral displacement of T7 to T10-vertebrae, increase of frontal inclination of L2 to L4 and elevation of the apical concave rib and in favor of reduction of lateral displacement of T11 to L4 vertebrae, decrease of frontal inclination of T7, T9 & T11 –vertebrae and derotation of L1 and L2 and thoracic apical vertebra without affecting drooping of the 7th to 12th ribs. In this series there was remarkable inconsistency in the obtained changes in several of the roentgenographic parameters in the different evaluations and this is probably due to the empiric application of TLSO during different periods of treatment. At an average of 3.5 years after termination of TLSO wearing all roentgenographic parameters remained approximately to the pre-brace values. Conclusions. TLSO program maintains the measured roentgenographic parameters at the prebrace levels in progressive adolescent idiopathic scoliosis whereas had no effect on the droop of the seven lower ribs. The TLSO treatment stopped progressing of scoliosis, reduced the number of patients coming to operation and thus it changed the natural history of scoliosis. 58 LATE AND EARLY ONSET INFECTIONS IN SPINAL SURGERY C. Kosay, O. Akcali, C.O. Ardic, R.H. Berk, E. Alici Dokuz Eylül University Dept. of Orthopedics Balçova Izmir, Turkey The treatment methods for early or late developing infections following spinal surgeries withinstrumentation have not been completely elucidated.The purpose of this study is to determine the rate and the treatment methods of early and late onset post-operative infection in spinal surgeries.A retrospective evaluation of 458 patients undergoing spinal surgeries withinstrumentation between 1993 and 1998. Patients with established infections prior to index operation were not taken to the study. Infection was considered as late-onset when the durationbetween the operation and the diagnosis of infection was more than one year.There were 17 (3.7%) postoperative infections. Posterior spinal instrumentation were used in 14 (82%) patients, and anterior spinal instrumentation were used in 3 (18%) patients. Late-onset infection was seen in 6 patients. In 2 (33%) patients with late-onset infection, microbiological cultures were negative, whereas in 1 (9%) patient with early-onset infection, no microorganism was cultured. Antibiotic regimen for the first operation was the same for every patient. (First generation cephalosporin prior to and 3 days after the operation). Specific antibiotics were administered after the isolation of the microorganism. n patients with late-onset infections, implants were removed. In patients with early-onset infections, implants were not removed in 3 patients. All patients with late-onset infections were managed with one surgical debridment, whereas, patients with early-onset infections required an average of 2.5 surgical debridment operations. Late-onset infections following spinal surgeries can be managed with implant removal, whereas for treatment of early-onset infections, more operations may be required.

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59 OUTCOME EFFICACY OF WHOLE SPINE MRI IN SUSPECTED METASTATIC DISEASE OF THE SPINE – RESULTS OF A PROSPECTIVE STUDY F.A. Krappel1, E. Bauer2, U. Harland1 1Orthopädische Klinik, Klinikum Saarbrücken, Winterberg 1, 66119 Saarbrücken; 2Bereich Kernspintomographie, Klinik für Strahlendiagnostik, Klinikum Saarbrücken, Winterberg 1, 66119 Saarbrücken, Germany Introduction: The sensitivity and specificity of MRI in detecting metastatic disease of the spine is well known. The decision when to perform the examination in the diagnostic ladder seems as yet not clearly stated. Aim: To prospectively investigate the outcome efficacy of whole spine MRI for diagnosis and treatment in patients with suspected metastases of the spine. Material and methods: All patients older than 50 years with newly diagnosed back pain and/or newly diagnosed spine- related neurologic symptoms without a diagnosis by other imaging modalities were accepted in this study. A whole spine MRI and a detailed MRI per spine region with suspicious lesions were performed using a Siemens Magnetom Expert 1,0 Tesla machine. Outcome efficacy was determined by assessing further therapy and result for the patient. Results: In all 15 patients of the year 1999 whole spine MRI allowed to determine the definite diagnosis and treatment. Plain X-ray and 99mTc bone scanning gave a diagnostic suspicion but no definite diagnosis or therapeutic consequence. Significance of findings: MRI of the spine including whole spine images allows clear cut decision making in diagnosis and treatment of cases suspicious of metastatic disease of the spine Conclusions: Careful history taking and clinical examination provide enough information to opt for whole spine MRI as the first choice investigation. This will provide maximum benefit to the patient and avoid examination cascades. 60 DOES PREOPERATIVE LOCAL ANAESTHESIA IMPROVE SHORT AND LONG TERM RESULTS AFTER MICRODISCECTOMY? RESULTS OF A PROSPECTIVE RANDOMISED CLINICAL TRIAL F.A. Krappel, M. Hippchen, U. Harland Orthopädische Klinik, Klinikum Saarbrücken, Am Winterberg, 66119 Saarbrücken, Germany Introduction: Microdiscectomy is still the gold standard for proven disc herniation not responding to conservative treatment. However, there is a certain percentage of patients where the operation seems the beginning of a chronic pain syndrome eventually leading to disability. Aim of the study: To evaluate whether reducing the local nociceptive stimuli of the procedure will improve early and late results of microdiscectomy. Material and methods: Thirty patients each were randomly allocated to either the L.A.(Local anaesthesia) or the non LA group. Exclusion criteria were more than 6 weeks of symptoms and previous disc operations.The Operation was performed by one of three senior surgeons each of them with a minimum five years experience in spine surgery. The LA group received 10 ml 0,75% Ropivacain to the lamina of the level above, the level to be operated on and the level below under image intensifier control and documentation. The operative procedure was the same in all patients using a standard microdiscectomy and fragment excision. Results: There was no significant difference in the recovery time, post op pain measured on a VAS scale, requirement of pain medication or return to work.

Significance of findings: Preemptive preoperative reduction of nociceptive stimuli via local anaesthesia seems to be of minor importance in the results of microdiscectomy. Conclusion: Other factors than local pain via the operative procedure seem to play a key role in short term and most likely also long term results of microdiscectomy. 61 A CONTROLLED PROSPECTIVE OUTCOME STUDY OF IMPLANTABLE DC STIMULATION WITH SPINAL INSTRUMENTATION IN A HIGH RISK POPULATION D.W. Kucharzyk The Orthopaedic, Pediatric & Spine Institute, 1205 S. Main Street Suite 201, Crown Point, Indiana, USA 46307 To test the efficacy of electrical stimulation in instrumented high risk lumbar fusion’s, Sixty five patients with instrumentation without stimulation were compared to sixty-five patients with instrumentation and electrical stimulation. The groups were evaluated for risk factors, age, diagnostic groups, levels fused, and success radiographically and clinically. It has been shown that spinal instrumentation and implantable electrical stimulation have improved fusion success rates independently and now this study looks at their use together in a high risk population. Instrumented spinal fusions were performed on one hundred and thirty patients with sixty-five patients placed each into two groups: one receiving electrical stimulation and the other not receiving electrical stimulation. All were instrumented via pedicle screws and autologous bone graft was used. The groups were evaluated for risk factors, age, diagnostic groups, levels fused, and radiographic and clinical success. Post Op management and followup was similar in each group. Radiographs were evaluated for fusion success and graded via Dawson’s criteria and confirmed by an independent radiologist and orthopaedic surgeon. Clinical success was evaluated via the Modified Smiley-Webster Scale. Statistical significance was evaluated via the Fisher Exact Test. In addition, a subset of Worker’s Compensation patients were identified and evaluated to correlate fusion success and clinical success with results of a Non-Workers Compensation group. Fusion success was 95.6% in the stimulated group compared to 87% in the non-stimulated group (p=0.05). Clinical success was 91% in the stimulated group versus 79% in the non-stimulated group (p=0.02). In the Worker’s Compensation subset, fusion success was 93% in the stimulated group compared to 81% in the non-stimulated group. Clinical success was dramatic in that, success was 57% in the stimulated versus 46% in the nonstimulated group. The use of both instrumentation and electrical stimulation in a high risk pool of patients has shown statistical significance with higher rates of fusion and clinical success when compared to a similar pool that did not receive stimulation. In worker’s compensation patients though, a high rate of fusion did not correlate with a high rate of clinical success and perhaps the reason is the patients pending claim. 62 A CONTROLLED RANDOMIZED OUTCOME STUDY ON THE EFFICACY OF CORRALLINE HYDROXYAPATITE FOR BACKFILLING THE ILIAC CREST. A STUDY TO ASSESS THE EFFICACY ON PAIN REDUCTION D.W. Kucharzyk The Orthopaedic, Pediatric & Spine Institute, 1205 S. Main Street Suite 201, Crown Point, Indiana, USA 46307 Corralline hydroxyapatite has shown a significant use in instrumented and uninstrumented posterior spinal fusion’s with excellent reported clinical success rates and fusion rates. Corralline has

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also shown clinical success in its use in lumbar interbody fusion’s via internal fixation utilizing cages. It has also shown its efficacy in trauma orthopaedics: filling in defects and voids from major skeletal trauma, as well as its use in tumor surgery and reconstructive surgeries. To see an additional potential benefit from corralline hydroxyapatite, a study was undertaken to see if backfilling the iliac crest post graft harvesting would decrease the level of postoperative pain and time to mobilization in instrumented lumbar fusion’s. A randomized controlled study was undertaken to test this hypothesis. A controlled randomized group of patients were obtained with twenty patients randomized into two groups. One group received Corralline to backfill the iliac crest after bone graft harvesting and the other did not. All patients underwent posterior spinal fusion with instrumentation and carried similar diagnosis, levels fused, age, and risk factors. Patients were evaluated for: time to mobilization, postoperative pain, rehabilitation levels, and incorporation. All were followed for a minimum of 2 years and are still being followed. Results revealed the following: with reference to pain, all patients were evaluated on an analog pain scale, and the Corralline group revealed a marked reduction in pain. Patients were evaluated in each group at three days, two weeks, one month, three months, six months, one year, and two years. In the NonCorralline group, results showed a pain level as follows: at three days-8, at two weeks-7, at one month-5, at three months-5, at six months-4, at one year-3, and at two years-3; but when contrasted to the Corralline group, results showed: at three days-6, at two weeks-5, at one month-3, at three months-1, at six months-0, at one year-0, and at two years-0. Time to mobilization was assessed and revealed in the Corralline group a one day sooner time to mobilization than the non-corralline group. This translated into a sooner rehabilitaiton of the Corralline group compared to the NonCorralline group and the translates into an overall improvement in functional outcome in this group. Incorporation was seen in all patients with Corralline. In conclusion, the use of corralline hydroxyapatite to backfill the iliac crest has shown a significant benefit to the patient and insurance carrier both. Its use has shown a decrease in pain over the first six months, and more significantly at one year, and this translates into a quicker time to rehab and an overall better functional outcome for the patient undergoing a posterior spinal fusion. 63 SAGITTAL ALIGNMENT IN NON-SEGMENTAL VERSUS INDEPENDENT -INTRASEGMENTAL PEDICLE SCREW SYSTEMS D.W. Kucharzyk, G. Alavanja The Orthopaedic, Pediatric & Spine Institute, 1205 S. Main Street Suite 201, Crown Point, Indiana, USA 46307 Purpose: Maintaining the normal lumbar lordosis is often difficult when attempting to fuse more than one lumbar segment. This is particularly true in the face of a sagittal plane deformity such as spondylolisthesis and/or a lateral motion segment listhesis. Technical advances have made contouring a straight rod somewhat easier, but correcting a multi-level three dimensional deformity with a straight rod can often be a daunting, if not impossible task. This study was performed to compare the ability of two straight rod(TSRH and Rogozinski) systems and one independent intrasegmental pedicle screw fixation system(SpineLink) to maintain the sagittal lumbar plane alignment over a two year follow-up. Methods: Twenty-five patients were assessed in each of the two rod systems and compared to forty patients receiving the independent intrasegmental fixation system. The three groups were compared with respect to age, male/female ratio, previous surgery, and number of levels fused. There was a minimum two year follow-up in each group. Radiographs were performed both preop and postop and standing lateral radiographs measured for lordosis. Lordosis

was measured as the angle between the superior endplate of L1 and the superior endplate of the sacrum. In addition, individual measurements of the L4–5 and L5-S1 angle of lordosis was assessed and the percentage of contribution of each to overall lordosis was determined and compared to the work of Jackson and McManus(Spine 19(14):1611–1618,1994) Results: The following table represents the degrees of preop and postoperative lordosis of the two rod systems and the independent intrasegmental fixation system. Additional results reflect the overall contribution of the segments to lordosis in the two rod systems and the independent intrasegmental system.

TSRH Rogozinski SpineLink P-value

Preop lordosis

Postop lordosis

47 deg 49 deg 46 deg 0.557

45 deg 49 deg 45 deg 0.092

Intrasegmental contributions to lordosis Jackson/McManus TSRH Rogozinski SpineLink

27% 26% 26% 26%

40% 41% 42% 43%

Discussion/Conclusion: It has long been recognized that the loss of the normal lordosis may result in flat back syndrome. Flat back syndrome and its concomitant loss of the normal lumbar sagittal spinal alignment typically shifts the truncal center of gravity anteriorly. This often results in an altered gait pattern, increased lumbar symptomatology, and abnormal biomechanical stresses on the unfused adjacent vertebral segments(Lagrone; OR. CLIN. NA 2: 383–43,1988 and Thomson; J.SP. DISORD. 2:93–8,1989). The importance of maintaining lordosis and avoiding iatrogenic flatback in the lumbar spinal fusion patients is of major importance to all spine surgeons. Lumbar fusion eliminates the dynamic features of the lumbar spine and if lordosis is lost, compensatory mechanisms enter into producing secondary changes. Rod contouring has addressed this issue and as our results indicate, have maintained preop and postop lordosis. But what’s important too, is that the independent intrasegmental system(SpineLink) also maintains the preop and postop lordosis as seen in this study, with the added feature’s of easier use, no contouring, reduced operative time, enhanced applicabilty, and greater independent segmental correctability. Furthermore, when intrasegmental lordosis contributions are assessed, our results were similar to that of Jackson and McManus and those of the rod systems, and this translates into maintenance of our lumbar lordosis and a reduction in the risk of iatrogenic flat back syndrome. 64 A NEW “INTRAMEDULLARY” ANTERIOR SPINAL FIXATION DEVICE: IN VITRO EVALUATION S.D. Kuslich, M. Garner, K. Roche, J. Gleason St. Croix Orthopaedics, Stillwater, Minnesota, USA Purpose: The purpose of this presentation is to report the results of a mechanical evaluation of a new device, the K-Centrum Anterior Spinal Fixation System. The K-Centrum is a unique “no-profile” device that has recently been cleared for marketing by the U.S. FDA. The system consists of large hollow bone-screw anchors that contain a slot into which a rectangular cross-sectioned rod is inserted. After implantation, the device is entirely “intermedullary” i.e. it is fully contained within the natural margins of the vertebral column.

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Methods: Using thawed fresh-frozen calf spines, we prepared five-vertebra segments by potting end segments in rigid cement. These specimens were then placed into a biaxial test fixture for loading. The semi-constrained fixture permitted rotation and slight translation out of plane, and eccentric compressive loads were applied to cause bending in each plane. Axial rotation testing utilized a fixed axis. Loading was applied to the specimens in five cycles, with load-displacement data collected from the fifth cycle only to allow for viscoelastic settling. The following loads were applied: axial compression to 500 N; flexion-extension and lateral bending to 8 N-m, and axial rotation to 10 N-m, under an axial compressive preload of 110 N. The intact spine was tested first, and then a complete corpectomy was performed, leaving the posterior elements intact. The corpectomy defect was then stabilized using the KCentrum device. The construct was completed utilizing a wooden dowel to simulate structural graft. Results: The K-Centrum exceeded intact stiffness in all loading modes except axial rotation, as seen in the summary graph below. K-Centrum stiffness in lateral bending tends to be symmetrical, owing to the central placement of the linkage rod. Discussion: The system is intended for use in tumor and fracture reconstruction from T-10 through L-2. The system appears to possess several potential advantages over existing cantilevered systems, including: absence of metal impingement on local peri-vertebral tissues, more uniform loading of corpectomy replacement graft, and more secure bonding of bone anchors – as a result of hollow design and fenestrations in the anchor walls that allow for bone ingrowth. The large anchors permit engagement in the denser subchondral cancellous bone. Finally, the relatively small diameter linkage rod permits excellent x-ray visualization of graft incorporation. 65 A BIOMECHANICAL EVALUATION OF A BONE GRAFTING TECHNIQUE USED FOR INTERBODY STABILIZATION S.D. Kuslich, S. Wolfe, J. Ahern, K. Roche, A. Dooris St. Croix Orthopaedics, Stillwater, Minnesota Purpose: To determine the segmental stability of a human motion segment when a surgical mesh in a predefined cavity contains interbody bone graft. Methods: We devised methods to produce a knitted polyester balloon and then developed tools and techniques to fill the balloon with highly compressed graft material. Five unconstrained human cadaveric specimens (L3-L4) were tested with a Selspot II optoelectric tracking system. The test setup applied a pure bending moment to the spine and could measure relative movement between vertebrae. The L4-L5 disc was used for all testing. The intact segment served as a control. The experimental group consisted of motion segments into which we injected morselized bone graft. The graft was contained within the surgical mesh balloon. We used morselized cancellous bone derived from calf vertebral bodies for all tests. Results: The unconstrained testing in human cadaver spines showed that an improvement in segmental stiffness is achieved when the mesh balloon surrounds the graft material. In flexion, the construct provided stiffness that was equivalent to that of the intact specimen. In all other bending mode the stiffness was increased. Extension stiffness increased by approximately 60%, lateral bending increased by approximately 30%, and rotational stiffness increased by approximately 50%. Post testing observations showed no migration of the graft material outside either the surgical mesh or the surgical defect. The surgical mesh packed bone graft fully conformed to the predefined cavity. Discussion: The use of surgical mesh to support and retain interbody bone graft increases of the stiffness of the motion segment,

compared to the intact spine. This construct might prove to be an effective method of interbody fusion. In vivo studies of this construct are in progress. 66 MODIFIED ANAESTHETIC PROTOCOL FOR ELECTROMYOGRAPHY MONITORING DURING ANTERIOR ENDOSCOPIC INSTRUMENTATION R. Kuzhupilly, I. Lieberman, R. McLain, D. Nair, I. Najm Clevealnd Clinic Foundation, A-41, 9500 Euclid Avenue, Cleveland, Ohio 44195,USA Objectives: 1) Define the anaesthetic protocol required to achieve optimal muscle relaxation. 2) Determine utility of EMG monitoring during anterior endoscopic lumbar surgery. Background: Muscle relaxation to a level of 0 twitches of the orbicularis oculi muscle necessary for adequate endoscopic exposure would interfere with Electromyography(EMG) monitoring which requires at least 2 twitches. The reported incidence of iatrogenic nerve injury or radiculopathy during such procedures is 1.7%– 4.7%. Perioperative EMG monitoring for the early detection of nerve injury is used during open procedures and would be desirable during endoscopic procedures too. Methods: We prospectively looked at 43 patients who underwent anterior endoscopic lumbar surgery with threaded fusion cages. The anaesthetic protocol involved induction with Pentathol and Fentanyl followed by intermediate acting nondepolarizing muscle relaxants. As the muscle relaxation wore off it was not topped off to achieve a twitch count of 2 during cage implantation. EMG activity was recorded bilaterally. At follow up improvement of any persisting symptoms as well as appearance of any new symptoms was correlated with EMG activity. Results: 21 patients (48.8%) had preoperative radicular symptoms with no clinical signs. At an average follow up of 8 months 13 patients had persistence of preoperative radicular symptoms. 2 cases out of 7 with brief discharges (28.5%) had some improvement of their symptoms postoperatively. 1 case with sustained discharge (>10 seconds) had no clinical improvement of preoperative radicular symptoms. 10 cases (23.2%), with no intraoperative changes also had persistence of preoperative radicular pain, albeit, with some improvement. 8 patients (21%) had exhibited intraoperative EMG activity corresponding to the level of surgery, with 3 patients showing additional activity in muscle groups innervated by adjacent roots above and below the level of surgery. 1 case developed a new radicular symptom postoperatively, but, had no perioperative EMG changes. A postoperative MRI showed no nerve root compression and her symptoms settled spontaneously. Conclusions: 1) Anaesthetic protocol can be successfully modified to facilitate EMG monitoring during endoscopic surgery. 2) The incidence of abnormal EMG discharges was comparable to open cases. 67 LUMBAR POSTERIOR SCREW FIXATION AND FUSION WITH MINIMALLY INVASIVE TECHNIQUE C. Lamartina, A. Zagra Istituto Ortopedico Galeazzi via Riccardo Galeazzi, 4-20161 Milan, Italy Minimally Invasive Spine Surgery (MISS) is becoming more popular. However, complex implants are not suitable for MISS. The objective of this study is to apply posterior screw fixation in MISS. In a prospective, non-randomised study we examined 25 patients (12/13 male/female; mean age 46) with a 2-year follow-up. Nineteen (group 1) had lumbar degenerative disc disease with signs of

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instability and 6 (group 2) had spondylolytic spondylolisthesis with 39% mean slippage. All patients suffered severe pain unresponsive to conservative treatment. This indicated stabilisation, fusion, and decompression where necessary. Two AO 4.5 mm cortical screws were used for translaminar fixation (Magerl’s method) in group 1 and two AO 6.5 mm cancellous washer screws with 16 mm threads for pediculo-body fixation (Grob’s method) in group 2. Both fixations were performed with posterior minimally invasive surgery. Blood loss was 150–250 cc and surgery time 50–120 minutes. All patients left hospital 2 days after surgery, without complications. Fusion resulted within 4 months in both groups. At the 2-year follow-up 13 patients in group 1 were pain-free and were working; 6 patients had pain which prevented working. Of the latter, 3 were multi-operated and 3 were operated on 2 discs. In group 2 all 6 patients were pain-free and were working; no further slippage occurred. MISS is less traumatic for patients and therefore gives better results at short follow-up compared to our results with traditional surgery. Short hospitalisation, fewer complications, faster return to work and better aspect are the key points in this technique. 68 CUSTOM-MADE IMAGE-BASED DRILLING TEMPLATES FOR PEDICLE SCREW INSERTION P. Lauweryns1, K. van Brussels2, J. vander Sloten2, R. van Audekercke2, G. Fabry3, W. Vancraen3 1Department of Orthopaedics, Univ.Hosp.Cath.Univ.Leuven, 1 Weligerveld, 3212 Leuven, Belgium; 2Division of Biomechanics and Engineering Design, Cath. Univ. Leuven, Belgium; 3Materialise NV, Belgium Introduction: High complication rates in up to 40% of cases with pedicle screws have been reported. Even with computer-assisted surgery there still exists a 4.3% malplacement rate. Aim of the study: The purpose of this study is to describe a new custom-made device which acts as a mechanical drill guide for pedicle screw insertion. The guide fits exactly on selected areas on the posterior part of one specific vertebra. Using CT-images of the patient’s vertebrae to be instrumented, preoperative planning software enables the surgeon to determine the optimal position and orientation of the screw. A CAD/CAM program designs a drill guide that features a stable, unique and correct position on the vertetra. Material and methods: A fourth generation prototype has been used in a cadaver study on three lumbar vertebrae. Later on three patients underwent a lumbar fusion using this device. Results: In the cadaver study all six pins were perfectly placed inside the pedicles as assessed on CT scan. A total of seven templates was used in three patients for the insertion of fourteen pedicle screws. A good, stable and unique fit of every template was observed. No case of pedicle cortex perforation was observed on plain X-rays and CT scans. 69 ANTERIOR VIDEO-ASSISTED T1 TO T3 APPROACH FOR METASTASIS J.C. Le Huec, E. Lesprit, C. Grinfeder, N. Gangnet CHU Pellegrin Tripode, Dept Orthopedie, 33076, Bordeaux, France Anterior cervico-thoracic junction is difficult to expose and many techniques have been published before. Most of them need a large exposure, leading to some complications. Less invasive approach is mandated. A less invasive technique allowing the same exposure on the spine as a large one, by using a video-assisted exposure is described.

Methods: An anatomic study on cadavers has been performed using an isolated manubriotomy. The use of the endoscope through a ten mm trocar in the third rib space, allows to minimize the approach. Three patients underwent this new approach for metastasis at the level T1 and T2. A strut graft was fixed anteriorly after decompression of the spinal cord. Results: Level T1 to T3 can be well exposed through this approach, allowing complete vertebral body removal at level T1 or T2. The dissection is performed on the left side, between esophagus and trachea medially, innominate vein and brachio-cephalic artery distally, and the left common carotid and internal jugular vein laterally. The recurrent nerve must be protected. After body removal the posterior longitudinal ligament is well exposed allowing complete release of the spinal cord. The manubriotomy is easy to reconstruct. Discussion: To exposed the cervico-thoracic junction the approaches are wide and need clavicle section or sternotomy, and for lateral approach scapula elevation with muscles damage and rib resection. Therefore they are subject to significant morbidity. Conclusion: This new approach is technically feasible. The exposure is sufficient for vertebral body resection and reconstruction by strut graft. This procedure is less aggressive and painful than sternotomy. 70 3-D CT VOLUME RENDERING TECHNIQUES IN ENDOSCOPIC THORACOPLASTY I. Lieberman, W. Davros, R. Kuzhupilly Cleveland Clinic Foundation, A-41, 9500 Euclid Avenue, Cleveland, Ohio 44195, USA Purpose: To define the utility of 3-D CT volume rendering of the spine and thorax in the preoperative planning of endoscopic rib resection. Introduction: Thoracoplasty is occasionally necessary to achieve an acceptable cosmetic result in the presence of a rib hump, especially in previously fused young adults with scoliosis. This usually requires the resection of 4–5 rib segments and the morbidity associated with open posterior resection or of open anterior resection via thoracotomy is often considerable, apart from leaving an unsightly scar. We felt the use of an endoscopic internal rib resection technique would achieve the desired result with less morbidity. Our experience with using the technique of 3-D CT volume rendering to plan our portals and releases for endoscopic scoliosis correction led us to believe the same techniques could be adapted to plan and endoscopically carry out the thoracoplasty. Methods: To assist in the preoperative planning, four patients with previously fused scoliotic spines and pronounced rib humps underwent helical CT scanning with 3-D volume rendering between June 1998 and December 1999, prior to endoscopic corrective surgery. All four patients had right sided rib humps requiring corrective rib resection for cosmetic reasons. Using the technique of 3-D volume rendering a vector plane was created to mirror the left scapula and its intersections on the right chest wall were noted. The ribs to be resected were marked and the length of rib resection was measured from the vector plane’s intersection points with the ribs. In this way an estimate of the resection required to achieve the desired final position of the right elevated scapula could be determined. Entry portals were also estimated with vector lines to achieve optimal access to each rib. During surgery the portal sites were assessed for access to the selected ribs. Also, the extent of rib resections was compared to the estimates. The final clinical outcome was assessed by clinical examination, patient satisfaction with the cosmetic result and repeat helical CT scanning with 3-D reconstruction. Results: The male female ratio was 1:3 and the average age was 21 years. Our average estimated blood loss was 327 ml and average hospital stay was 4.75 days. The estimated portal sites were ac-

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curate and did provide for direct access to each selected rib involved in the deformity. We were able to resect the ribs at the points suggested by 3-D CT volume rendering, with the lengths of our resected segments matching our preoperative estimates. In all cases the elevated right scapula did descend into the rib resection bed thus balancing the shoulder heights. An excellent cosmetic result was achieved in all cases as evaluated by clinical examination, patient’s perception and repeat helical CT scanning. Discussion: The technique of 3-D CT volume rendering in the preoperative planning for endoscopic spinal deformity surgery does provide a virtual estimate of the portal sites and extent of rib resection which can be duplicated in the OR. We found that we could create the portals with more confidence knowing that with the estimated trajectory we had direct access to the targeted ribs. We were pleased with the technique of estimating rib resections for thoracoplasty and its clinical cosmetic result. The philosophy of endoscopic surgery is to access the pathological structures through small portals minimizing collateral damage to non-pathological tissues. The 3-D CT volume rendering technique allowed us to perform the procedures through a minimal number of portals precisely focussed on the surgical site. Conclusion: The technique of 3-D CT volume rendering provides a reliable estimate of the rib resection required to achieve a cosmetically acceptable correction of the rib hump through minimally invasive techniques

71 HOOK VERSUS PEDICLE SCREW INSTRUMENTATION IN POSTERIOR CORRECTION AND FUSION OF IDIOPATHIC THORACIC SCOLIOSIS U. Liljenqvist, U. Lepsien, L. Hackenberg, T. Niemeyer, H. Halm Department for Orthopedic Surgery, Westfälische Wilhelms-Universität, Albert-Schweitzer-Strasse 33, 48149 Münster, Germany Purpose of the study: The role of pedicle screw instrumentation in thoracic scoliosis correction and fusion remains highly controversial. Aim of this study was to compare hook versus pedicle screw instrumentation in 89 cases of idiopathic right thoracic scoliosis. Methods: Forty-nine patients (average age 16,3years) with right thoracic idiopathic scoliosis have been treated by posterior correction and fusion using combined pedicle screw and hook or exclusive pedicle screw instrumentation at our department. All patients have been followed prospectively with a minimum follow-up of 24months (average 33,3months, maximum 62months). This group (screw group) was compared with a group of retrospectively collected data of 40 patients with right thoracic idiopathic scoliosis (hook group, average age 17,1 years) who were surgically treated with exclusive hook instrumentation (average follow-up 80 months, 24–136months). Radiometric analysis included Cobb angle, apical vertebral rotation (AVR), apical vertebral translation (AVT), tilt angle of the lowest instrumented vertebra (LIV) and sagittal profile on the preoperative, postoperative and latest standing a.p. and lateral radiographs and was completed by an unbiased observer. Results: Statistical analysis revealed a significantly greater curve correction of primary and secondary curve, of the AVT and the LIV in the screw group (p<0.05). There was no significant difference between the Cobb angle at 24 months and latest follow-up (p>0.05). Apical vertebral derotation was negligible in both groups. Sagittal curve correction was equally satisfactory in both groups. Operative time and blood loss were significantly less in the screw group (p<0.05). Distal fusion length was on average 1 segment shorter in the screw group (p<0.05) with an average fusion of one segment distal to the lower end vertebra in the screw group. One pedicle screw was revised due to anterolateral vertebral body penetration at T5 and direct proximity to the thoracic aorta.

Cobb angle -primary curvescrews hooks preop.

bending postop. followup correction

Cobb angle AVT -secondary curvescrews hooks screws hooks

62.5° 62.0° 39.7° 37.8° 4.5 cm (43–94) (40–84) (20–72) (12–74) (2.8– 7.5) 40.7° 38.4° 16.5° 11.3° – 27.6° 30.6° 16.2° 16.6° 1.6 cm (14–52) (14–52) (0–38) (2–37) (0–3.7) 31.1° 37.8° 17.9° 20.1° 2.0 cm (16–58) (14–67) (2–38) (4–38) (0.3– 4.0) 50.2% 39.0% 54.9% 47.0% 55.6%

LIV screws hooks

5.1 cm 20.7° 17.8° (1.5–8.5) (6–34) (0–38) – – 2.4 cm 6.3° (0.5–6.5) (0–16) 3.0 cm 7.0° (0.5–6.9) (0–18)

– 7.7° (0–24) 10.1° (0–28)

41.2%

43.3%

66.2%

Conclusion: Pedicle screw instrumentation alone or in combination with proximal hooks offer a significantly better correction of idiopathic thoracic scoliosis with a significantly shorter fusion length than exclusive hook instrumentation. 72 MINIMALLY INVASIVE ANTERIOR RETROPERITONEAL APPROACH FOR INTRADISCAL LUMBAR FUSIONS G.L. Lowery, S.S. Kulkarni Research Institute International Inc., 10645 N. Tatum Blvd. Suite 200-# 614, Phoenix AZ 85028, USA Purpose: The search for techniques to reduce morbidity of surgery for multi-level lumbar anterior intradiscal fusions; has led to our philosophy of combining minimally-invasive anterior retroperitoneal approach to the lumbar spine with posterior stabilization by percutaneous suprafascial instrumentation. Methods: This is a retrospective study of 47 patients undergoing Mini-ALIF procedure between Feb-97 and Aug-98 having more than 6-months follow-up. (F/U %=97%, Average F/U 12.8mo). Average age was 46 yrs,18 had previous surgery. Intradiscal fusion was performed by minimally-invasive anterior extraperitoneal approach. CarbonFiber-Spacer was used with IP500dowels or autograft in 32 pts, BB-femoral ring with autograft in 9 pts, and Synthes femoral ring allograft alone in 6 pts. Fusion was 1-level in 12 patients, 2-level in 32 patients and 3-level in 3 patients. 43 patients had posterior percutaneous suprafascial instrumentation, 4 had posterior fusion and instrumentation. Results: Major complications were Iliofemoral thrombo-embolism in 3 patients and Iliac vein injury in 3 patients. No ureteric or parasympathetic plexus injury was seen. Average VAS decreased from 8.4 to 5.8. 41 patients (87%) had solid fusion at all levels. Three patients required posterior salvage procedure. 81(93%) of total 87 levels operated showed solid fusion. Fusion failed at the L3–4 level in 2 patients, L4-L5 level in three and L5-S1 level in one. Conclusion: The Mini-ALIF approach provides adequate and safe exposure for multilevel lumbar intradiscal fusions even for levels as high as L1-L2, as opposed to laparoscopic approach. Concomitant posterior stabilization helps achieve better success even without posterior fusion 73 VERTICAL SPACERS (TSM) WITH POSTERIOR INSTRUMENTATION FOR LUMBAR INTERBODY FUSION: LONG TERM RESULTS G.L. Lowery, S.S. Kulkarni Research Institute International Inc., 10645 N. Tatum Blvd. Suite 200-# 614, Phoenix AZ 85028, USA

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Introduction: Titanium Surgical Mesh (TSM) is structurally strong, biocompatible and a versatile spacer for interbody fusion providing early consolidation and graft incorporation. Methods: This is a retrospective analysis of 212 patients operated between Mar-91 and Oct-99, for lumbar interbody fusion using TSM-bone construct with posterior instrumentation with or without posterior fusion (F/U=98%). Average follow-up=43 months (range 6–96).Interbody fusion was performed anteriorly (ALIF) in 93 cases and posteriorly (PLIF) in 119 cases. 66% of the cases had prior surgery. Autograft alone was used within the cage in 57% cases and in combination with allograft, ProOsteon or Grafton in 43%. Rigid posterior instrumentation (Moss Miami-52, TSRH-45, others-34), flexible (MOSS-75) or percutaneous (USS titanium –6) stabilization was employed. Posterolateral fusion was performed in 173(82%) cases. Results: Complications included incidental durotomy(8%), Infection(7%), Vascular injury(0.5%), DVT(3%) and transient neurological problems(5.1%). Long term complications were painful posterior instrumentation(10%), hardware failure(5%), transitional syndrome, adjacent level pain or flat back requiring surgery(13%), persistent radiculopathy requiring root decompression(6%) and anterior incisional hernia(1%). 17 patients(8%) had failed fusions. Of these 17 failures, five patients needed repeat anterior-posterior procedures while four had salvage posterior fusion and instrumentation. Subjective patient satisfaction (VAS) was noted in 80% of cases. Solid interbody fusion was observed in 92% of cases either at instrumentation removal surgery or on radiology. Conclusion: This long term follow up study reveals that TSMbone constructs supplemented with posterior stabilization allows optimal anterior column reconstruction and early biological fusion even for patients with failed previous surgeries. 74 SPONTANEOUS DISAPPEARANCE OF A LARGE CALCIFIED THORACIC DISC HERNIATION. MRI EVALUATION L.A. Lozano-Requena, M.T. Avila-Gellida, P. Cano-Luis Hospital Vegabaja, Ctra. Orihuela-AlmoradÌ s/n. San Bartolomé. Orihuela. Alicante. Spain Hernitation of the calcified nucleus pulposus through the fibrous annulus is unusual in childhood. We report the case of a boy who complained of thoracic spine pain for the first at the age of ten. On presentation he was hyperreflexic in both lower extremities. Slight spasticity was noted on ambulation, though motor strength was intact. Genital and rectal sensation were normal. Plain films of thoracic spine showed calcification of T3-T4 and T5 –T6 levels. MRI verified a large T3-T4 disk herniation with dural displacement and canal compromise. With conservative treatment his symptoms resolved within four weeks. One year later, the patient experienced spontaneous resolution of the herniated disk at T3-T4 level. Hernitation of the calcified nucleus pulposus is a complication of intervertebral disc calcification. We analyze the evolution by means of MRI and scintigraphy showing that corresponds to a benign abnormality. The surgical indication must be based on the natural history of this pathology. 75 SUPINE BENDING OR TRACTION – WHICH SHOWS BETTER SCOLIOSIS FLEXIBILITY? T. Lukaniec, P. Menartowicz, K. Koltowski Centre of Rehabilitation & Orthopaedics, ul. Lesna 1, 55–100 Trzebnica, Poland The aim of the investigation was to assess two methods of preoperativeevaluation of scoliotic curve flexibility. The first one was

supine bendingfilm, the other one traction film in upside down position. Authors discuss100 cases of right scoliosis assessed before the operation. Mean Cobb anglewas 70 degrees, the average patients age 15 years. All the patients hadsupine bending films and x ray under traction on the special frame beinghung upside down with about 10 kg weight applied by Glisson halter. Theobtained correction was compared.The resultsIn cases of moderate curves under 60 degrees the rate of correction on thesupine bending film was 32% against 48% on the traction film. Severecurves over60 degrees – 19% of correction on bending film against 38% on the tractionfilm. On average in both types of curves there was 43% correction undertraction and 26% correction on the bending film.ConclusionsTraction film shows better the flexibility of scoliosis than supine bending.Supine bending to the convex sie of thoracic scoliosis does not provide anymore information needed for preoperative implant planning and estimating thecorrection. Thus it may be abandoned everytime the traction film may beobtained.Authors also describe the technical aspect of performing the x-ray examination under upside down traction.

76 RADIOLOGICAL ABNORMALITIES AND BACK PAIN OF THE THORACO-LUMBAR SPINE IN ATHLETES. A LONGTERM FOLLOW-UP O. Lundin, M. Hellström, I. Nilsson, L. Swärd Dept of Orthopaedics, Sahlgrenska University Hospital, Göteborg, Sweden Objective: To study the long-term outcome of radiological abnormalities in the thoraco-lumbar spine of top athletes representing different sports, and to analyze its correlation to back pain. Methods: A radiological follow-up study of the thoraco-lumbar spine was performed in 135 top athletes representing different sports (gymnastics, soccer, tennis and wrestling), and in a reference group of 28 non-athletes. The follow-up period was 12 to 15 years and comprised 94% of the participants at the initial examination. Radiographs of the thoraco-lumbar spine, and a questionnaire regarding back pain were assessed both at the initial study and at follow-up. The radiographs were evaluated in a blinded manner by two radiologists. Results: Various types of radiological abnormalities occurred in all groups of athletes and non-athletes, but were more common among athletes. Progression of disc height deterioration and formation of osteophytes were significantly more common in wrestlers, soccer players and tennis players. Back pain was not significantly different among the athletic groups when compared to nonathletes. No relationship was found between the number of radiological abnormalities and back pain. When progression of disc height between the two examinations was studied, a significant relationship between disc height reduction and back pain was found. There was also a significant association between the number of deteriorated discs and back pain. Conclusion: The spine is most vulnerable for athletic trauma during the growth period, and mainly injuries in the disc seem to be at risk of long-term radiological deterioration. A correlation was found between back pain and an interval deterioration of disc height, which may be due to an injured disc.

77 DOES PROVOCATIVE DISCOGRAPHY HELP IN LOW BACK SURGERY? S. Madan, J.M. Harley, N.R. Boeree, M. Sampson Southampton General Hospital, Tremona Road, Southampton, UK

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Purpose: To investigate the efficacy of provocative discography in improving the outcome of low back surgery. Background: Between 1995 and 1997, 2 group of patients who underwent low back operation were studied. Group A had pre-operative provocative discography in addition to MRIscan as a diagnostic procedure and group B had only MRI scan. 2 patients had no provocation at discography and thus did not have any operation. Post-operative outcome was measured at a mean follow-up of 2.6 years for group A and 2.4 years for group B. There were 40 patients in group A and 71 patients in group B. The patients were assessed using the Oswestry disability index, a subjective index, Zung Depression Scale [ZDS], and Modified Somatic Perception Questionnaire [MSPQ]. The groups were matched for age, sex, severity of disease, and index operation. The operations were: Operation

Graf

ALIF-HH

Graf+ Fusion

PLIF

Total

Group A Group B

18 26

7 14

3 5

12 26

40 71

ALIF- Anterior Lumbar Interbody Fusion using Hartshill Horseshoe cage. PLIF – Posterior Lumbar Interbody Fusion

Following table shows the outcome: Outcome

Worse

Same

Better

Excellent

Chi-square

Group A Group B

1 5

6 8

10 14

23 44

P=0.6427

There was no statistical significant difference between the 2 groups. This raises the question how specific is a negative provocative discogram in selecting the patients for low back operations? Conclusion: This study shows that provocative discography procedure in isolation may not be effective in patient selection for low back surgery. Patient’s objective physical signs, MRI, and nerve root injections along with provocative discography should be a pre-operative diagnostic armamentarium for patient selection in low back surgery.

Conclusion: Although preliminary, this study supports the use of computer assisted guidance as a safe and reliable option for the insertion of pedicle screws in scoliotic spines. It reduces the misplacement rate significantly and allows any surgeon to place screws safely on higher levels, even in a deformed spine. 79 A MATHEMATICAL TOOL FOR SPINE BALANCE J.Y. Margulies, R.A. Adler, A.D. Kalvin, M. Martens, M. Shub IBM Watson Research Center, Yorktown Heights, New York, USA This aim of this work is to develop a mathematical tool that associates geometric data with local and global deformation and deforming factors. It identifies various deforming factors and isolate groups with these factors within the idiopathic scoliosis or other spinal imbalance patients population. The model will also enable prediction of deterioration, early arrest of deformity, and planing for the optimal surgical correction. The model relies only on data absolutely measurable and reproducible. For the spine, these are geometric quantities such as exact coordinates of vertebrae in space and limits on ranges of motion. The tool is tested by means of computer simulations: local anatomical deforming factors are entered as inputs to a computer program and outputs of runs are compared with scoliotic and unbalanced deformities. These simulations are based on algorithms derived from a mathematical concept of the spine that resembles Hooke’s law. We incorporate raw data available from imaging scanners into a mathematical tool. The tool is built to construct a good 3-dimensional representation of the patient’s spine, rendering the spine in neutral position and through the full normal and pathological range of motion. In addition the tool will be capable of incorporating growth and 3D progress of the deformity over time within the building blocks of the spine; i.e. the vertebrae and the spaces between them, and of reducing deformities on the screen. The latter function can indicate the existence of a primary deforming factor(s), as well as plan corrections. Finally, we emphasize that this project based on the use of only strictly measurable geometric data. 80

78 COMPUTER PLANNING AND IMAGE GUIDED PLACEMENT OF PEDICLE SCREWS FOR SCOLIOSIS SURGERY G. Mahieu, D. Vandevelde, J. Sys, T. Leenders, J. Michielsen University Hospital Antwerp, The Netherlands

PATIENT-ORIENTED OUTCOMES OF AUTOMATED PERCUTANEOUS LUMBAR DISKECTOMY. A RETROSPECTIVE COHORT STUDY OF 61 OPERATED PATIENTS WITH 6 (2–10) YEARS OF FOLLOW-UP L. Massari, A. Brunoro, A. Gildone, G. Zanoli Department of Orthopaedics, University of Ferrara, Italy

Background: Pedicle screw insertion is known to be a reliable but delicate operation, especially in the surgical management of scoliosis. According to literature, conventional insertion of pedicle screws may result in a significant amount of malpositioned screws (20–40%) with possible complications. Methods: Fourteen patients with a mean age of 19 years old were operated with computer assistance for a total of 75 screws. Ten patients had idiopathic scoliosis and four had neuromuscular scoliosis. Screws were placed from level D 7 to S1. CT-scans were taken after the operation. Screws were scored as being placed correctly, 0–2 mm or 2–4 mm out of the pedicle. Results: Four out of 75 screws were placed incorrect (5.33%). Three screws were in group II (4%) and one in group III (1.33%). The screw in group III was inserted too medial at D11 on the convex side. The screws in group II were at the concave side at D9, D12 and at L4. One was too medial and two were too lateral. None of the patients had neurological complaints. When only the dorsal screws are taken into consideration 3 out of 32 screws were incorrectly inserted. (9.37%).

Introduction. Despite the widespread adoption of APLD there are few outcome studies and reports about middle-term Results. A recent systematic review of surgery for lumbar disc prolapse concludes that there is moderate evidence that percutaneous discectomy produces poorer clinical results than standard discectomy or chemonuclelysis. However, authors also state that there is still no clear evidence about the clinical outcomes in APLD. A retrospective cohort study of self-reported HRQoL in patients operated with automated percutaneous lumbar discectomy (APLD) at one institution with a mid term follow-up (6 yrs., range 2–10) has been performed in order to evaluate the mid-term patient-centered outcome in patients operated on with APLD. Methods. Charts of 99 consecutive patients, mean age 46 (20–85) years, operated from 1989 to 1997 by a single surgeon (L.M.), were retrieved. Level of operation was L3-L4 in 7 cases, L4-L5 in 59, L5-S1 in 26 and a combination of those in 7. Suggestions of Smith et al. (1998) for locating missing patients in long-term clinical studies were followed. Data were reviewed by an independent observer (G.Z.). Inclusion criteria were severe sciatica resistant to

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conservative treatment for 6 weeks or more, with consistent clinical finding and neuroradiologic examination showing disc protrusion at the symptomatic level, without a complete herniation. Selfassessment questionnaires (AAOS, lumbar module), which include SF-36 and a disease-specific questionnaire (Daltroy 1996) were either mailed or personally administered to patients who met inclusion criteria and agreed to participate in the follow-up study. Results. 10 patients (10%) had been re-operated and were therefore excluded from the study. 1 patient had died, 2 patients had a stroke and were unable to complete the questionnaires. Of the remaining 86 patients, 61 (71%) agreed to answer the questionnaires. 39 were males and 22 females. The presence of a selection bias regarding demographic and pre-operative characteristics of respondents and lost-to-follow-up was excluded. SF-36 scores were slightly lower than the age-matched normative data, in the following dominions: Phisical function (PF), Role Physical (RP), Bodily Pain (BP) and Role Emotional (RE). Comparison with normative data for a subgroup of patients with sciatica showed higher scores for our sample in all dominions except RP. Significant correlation was found between generic and specific scores and other parameters, such as drug intake, physical requirements of job type and search for specialists’ advice. Conclusion. Measuring HRQoL with SF-36 and the AAOS lumbar module is a useful tool in spine patients. Percentage of subsequent open discectomy in our population (10%) was lower than previously reported for a group of conservatively treated patients (26%, Weber 1983). Quality of life scores in a sample of patients operated by means of APLD with a mid-term follow-up show in general worse results than the age-matched healthy population, but better results than a sample of patients with sciatica. This might indicate that they represent a group with intermediate characteristics and that with limited indications, APLD might be an effective alternative to conservative treatment of disc protrusion. 81 CERVICAL CAGE FUSION. FIVE-YEAR EXPERIENCE WITH 185 CASES G. Matgé Neurosurgical Department, Centre Hospitalier de Luxembourg, Centre Hospitalier, 4, rue Barblé, LUX – 1210 Luxembourg

ence. The fact there was no graft harvesting (and related complications) saved operating time, blood loss and hospital stay. 82 SOURCE OF THE ALTERNATIVE BLOOD SUPPLY OF THE SPINAL CORD A. Matiouchine Research Institute of Traumatology and Orthopaedics, Novosibirsk, Russia The circulatory failures are the main obstacle for anatomic and functional regeneration of injured spinal cord. Its revascularization by omentomyelopeksy is irrational and has high risk of fatal complications. The physiological ability of spontaneous anastomosis formation between arteria intercostalis (AI) of the transposed intercostal neurovascular pedicle flap (INVPF) and arteries of the posterior spinal cord (myelo-myosynangiosis) was determined. INVPF from the seventh right intercostal space was transposed on the posterior spinal cord (T8-T9) without pleuracotomy. InGroup A (n=8) coagulation devascularisation of the posterior spinal cord (T8) was. In control Group B (n=4) the spinal cord remained intact. Three plane arteriogramms revealed arterial anastomosis between INVPF and the spinal cord. Neurological status was estimated by themodified classification (Tarlov, 1957). The experiment was out in 9 mongrel adult dogs with average weight 12.3 kg and follow-up ranged from 15 days to one year. In ten out of twelve cases (A=6, B=4) the AI permeability of the advanced flap was confirmed on all its extent. Anastomosis between INVPF AI and arteries of the posterior spinal cord were confirmed in Group Ain fore out of six cases (at 30, 60,180, 365 day after operation) on arteriogramms only in one of three standard planes. In Group A (n=4) almost complete recovery after paraplegia was observed at 180–365 days. In Group B the anastomosis was not confirmed. Spontaneous anastomosis between arteries of INVPF and of those of the posterior spinal cord could be formed in devascularized site of the posterior spinal cord due to reparative angiogenesis during the incorporationof the advanced INVPF. In future this method might be considered as a way of revascularization of the injured thoracic spinal cord. 83

Anterior decompression with interbody fusion is the surgical procedure of choice in cervical spondylosis. Graft harvesting complications among other favoured development of cage fusion technology. This retrospective study analyses 185 consecutive cases treated by interbody cage fusion with 4 different implants. Threaded titanium cages (BAK, n=149) were first used for autostabilising properties, then impacted Peek cages (Signus, n=10 and Novus, n=6) for better elasticity and radioluency, and finally a novel type of titanium cages (Wing, n=20) presenting advantages of cylindrical and sqared implants. Indications for fusion concerned degenerative discopathies, disc herniation and selected cases of failed surgery including pseudarthrosis. Clinical requirements were cervical radiculopathy (170 cases) or myelopathy (15 cases) confirmed by neuroradiological studies, mainly MRI. A standard anterior approach was used with specific instrumentation for distraction, endplate preparation and cage insertion, using local graft or bone substitute. Clincal results were excellent for cervical radiculopathy, but less favourable for myelopathy, needing a further decompressive operation in 30% for stenotic canal conditions. Radiological bone fusion assessement was easier with Peek, but all cases were consolidated at 1 year. Complications leading to early reopertion included cage migration (3 p) and cage subsidence (1 p) stabilised with a plate. Adjacent level degeneration (6 p) and additional decompression in stenotic myelopathies (5 p) needed late reoperations. Respecting indications and observing exclusion criteria, interbody cage fusion seemed promising in this 5-year experi-

THE COMPENSATION ABILITY OF BLOOD CIRCULATION SYSTEM IN SPINE FUSION OF THE ANTERIOR PEDICLE RIB STRUT GRAFT (APRSG) A. Matiouchine Research Institute of Traumatology and Orthopaedics, Novosibirsk, Russia It is unknown whether the intercostal arteries (IA) of the APRSG are the only source of its adequate circulation or the formation of additional sources of blood supply occurs during its evolution. Physiological possibility of the additional source formation for blood supply of the APRSG due to spontaneous anastomosis (myosynan-giosis) was qualitatively determined. The T7-T11 IA were coagulated. The anterior spine defect was bridged by APRSG with one (Group A) and with two adjacent (Group B) neurovascular intercostal complexes. The free end of the graft muscular cuff with IA was immersed and fixed subpleurally in the costovertebral angle of T8, 9,10 or T11. The qualitative estimation of graft blood supply was performed by postmortal arteriography in three standard planes. The arteriogramms of 23 adult dogs with average weight 14.3 kg and follow-up from 1 day to 1 year were studied. Permeability of all IA of the unfree rib graft was confirmed in 20 out of 23 cases. Heterocladic anastomosis between IA of the graft (muscle cuff) and IA of the recipient site (15,45,90,180 and 365 day after plasty) were observed in 14 cases from 23 (more 60%). We distinguished two

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types of anastomosis: a. scatter type – by means of multi-tude of small arteries, in both Groups A (n=2) and A (n=8), b. main line type – by means of big segmental intercostal artery, only in Group A1 (n=4). Physiological possibility of spontaneous formation of the anastomosis between IA of the intercostal pedicle flap and IA of the recipient site (myosynangiois) is qualitatively confirmed. The compensation ability of blood circulation system provides the formation of the additional source for blood supply of vascularized graft on the basis of processes of reparative angiogenesis,which could improve outcomes af-ter unfree and free vascularized transplantation. 84 THE ANTERIOR PEDICLE RIB STRUT GRAFT (APRSG) IN RECONSTRUCTIVE-CORRECTIVE SPINE SURGERY A. Matiouchine, V.A. Gavrilov, M.Y. Sizikov Research Institute of Traumatology and Orthopaedics, Novosibirsk, Russia APRSG is mechanically weak and curved, and anterior spine reconstruction with free vascularized fibular strut graft is irrational in the thoracic spine.The purpose was to determine the effectiveness of reconstruction of the anterior spine with APRSG without additional bone plasty after posterior instrumental fixation. All patients underwent wide anterior decompression of the spinal cord with total removal of 2–6 vertebral bodies, posterior resection or laminectomy followed by radical correction and posterior spine instrumentation, and plasty of the anterior spine defect with the pedicle rib graft including two intercostal neurovascular complexes without additional osteoplasty. The patients were followed from 2 to 7 years. Four patients were operated on: two – with severe thoracic Neurofibromatosis kyphoscoliosis with paraparesis (hyperkyphosis 167 and 178 degrees); one – with congenital thoracic kyphosis (98 degrees) with paraperesis; and one – with burst fracture of T4-T5 (angular kyphosis 50 degrees) complicated with paraplegia. Bipolar consolidation was seen in all patients within 30–90 days. In all cases radical correction of hyperkyphosis was preserved. The transformation of the rib into monolithic strut column occurred due to change in its shape and hypertrophy, and depended on graft loading. There were two hypertrophy spurts in the process of remodelling of the rib graft: first in 90–120 days after plasty, and second, with activation of mineralization, in 30–90 days after removal of the instrumentation. Initial load limitation on the APRSG through posterior spine fixation and its resumption after incorporation of the bone graft is necessary and sufficient conditions for anterior spine reconstruction. Instrumental fixation allows abandoning additional plasty and time consuming strut grafting with free vascularized fibular. 85 THE CORRECTION OF SPINE DEFORMITY AFTER PRIMARY UNSTABLE PLASTY OF THE ANTERIOR DEFECT WITH SEGMENTED PEDICLE RIB GRAFT A. Matiouchine, V.A. Gavrilov, A.M. Zaidman Research Institute of Traumatology and Orthopaedics, Novosibirsk, Russia The processes of reparative regeneration and the law of corrective mechanics of severe spine deformity require repeat anterior approach to restore anterior support after completion of radical correction. The physiological possibility of radical reconstruction of the anterior column after primarily unstable plasty by correcting spine deformity with segmented pedicle rib graft was studied. After total removal of four vertebral bodies (T6-T9) the segmented pedicle rib graft from the sixth rib with subperiosteal defect of the bone in the centre of the rib was formed. The graft was bent and its ends were fixed to supporting vertebral bodies T5 and T10 by su-

tures. In thirty days the instrumental correction of spine deformity (T3-T13) by unbending and distraction was performed. Three months later instrumentation was removed. The Results: were estimated by X-ray, contrast, histology and morphometry examinations. The experiment was carried out in 36 dogs with the average weight 14.4-kg. Follow-up ran-ged from one to 365 days. Spine deformity was formed after primary unstable plasty, with following correction of kyphosis and scoliosis by 63%–78% and telescopic shortening by 27%–34%. Rupture of the regenerate in the site of intersegmental defect of the rib graft occurred at the moment of correction. Formation of distraction regenerate with consolidation of bone fragments was observed in 60–90 days after plasty. Loss of correction after removal of the instrumentation was not revealed. Average hypertrophy of the bone graft was 247,5%, with similar degree of hypertrophy in both its bone fragments. There were two hypertrophy spurts: first after plasty, and second after removal of the instrumen-tation. The possibility of spine deformity correction on the “mild bone callus” of the segmental pedicle rib graft and the ability of its fragments for consolidation, hypertrophy and remodelling could be used in a complex treatment of severe spine deformities to decrease the number of surgical stages, their traumatic effect and hospital stay. 86 OPERATIVE DEMOGRAPHICS OF 500 CONSECUTIVE LUMBAR MICROSURGERIES J. McCulloch, D. Snook, J. Kruse Akron General Medical Center, Akron, OH, USA Study design: A retrospective review of 500 consecutive degenerative lumbar spine microsurgeries by a single surgeon. Objectives: Because of early reports of high complication rates, there is a reluctance by Orthopaedic Spine Surgeons to use the operating microscope. Methods: Five hundred consecutive charts of microsurgical procedures were reviewed, including a one month post-operative review for deep wound infections and early re-operation. Results: The procedures included discectomy (primary and revision), and spinal stenosis decompressions, with and without microsurgical fusion. The average age of the patient population was 64 years. The average operating time (skin-to-skin) for all cases was 68 min; the average blood loss was 129 cc. The dural tear rate was 1.6%, postoperative complication rate was 12.3%, most of which were urinary retentions. There were no serious complications such as death, pulmonary embolus or paralysis, or root injury. There were no deep infections and there was a superficial wound infection rate of 2.7%. The average length of stay was 1.3 days and the early re-operation rate was 0.6%. Demographics for each group of surgeries will be presented. Conclusion: In this group of microsurgical patients, the operative time, the blood loss, the dural tear rate, the root and cauda equina injury rate (0%), the deep wound infection rate (0%) and the average length of stay are all well below published reports in the literature for standard degenerative spine surgery (without use of the operating microscope). The microscope makes one a faster, and safer surgeon. Why don’t Orthopedic Spine Surgeons use the microscope for surgery in degenerative lumbar spine problems? 87 FORAMINAL STENOSIS-UNDEROPERATED BY SURGEONS J. McCulloch, B. Weiner Summa Health Systems, Akron OH, USA Study design: A prospective and retrospective analysis of foraminal stenosis in association with spinal canal stenosis.

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Objectives: The proper approach to foraminal stenosis is accurate diagnosis by MRI and surgical decompression from a lateral approach Methods: Fourteen patients with residual leg pain following a midline canal decompression were determined to have residual foraminal stenosis on parasaggital MRI. All patients were followed up a minimum of one year after a paraspinal approach for foraminal decompression. Nine patients with foraminal stenosis delineated pre-operatively underwent a combined midline canal and lateral foraminal decompression with a minimum follow up of one year. Results: In the retrospective review of fourteen patients with residual foraminal stenosis, eleven had relief of residual leg pain. In the prospective study of nine patients with foraminal stenosis, eight had relief of leg pain. Conclusion: Foraminal stenosis, when present on parasaggital MRI is best decompressive surgically through a paraspinal (lateral approach). 88 ANTERIOR LUMBAR INTERBODY FUSION IN THE TREATMENT OF DEGENERATIVE CONDITION OF THE LOWER LUMBAR SPINE – RADIOLOGICAL ASSESSMENT OF STABILITY OF THE SEGMENT M. Mehta, A.S. Wojcik Hinchingbrooke Hospital, Orthopaedic Department, Huntingdon, Cambridgeshire, PE18 8NT, UK Anterior Lumbar Interbody Fusion has a significant role in the treatment of the degenerative disc disease,of the lumbar spine.Different techniques of this procedure were described over the years leading gradually to minimally invasive approaches in recent several years to minimalise the adverse effect of conservative open surgery. Our practice based on experience gained from performing this type of surgery since 1995 is based on minimally invasive approach through the extraperitoneal route to L4-L5,L5-S1 and higher levels in the lumbar region. The extraperitoneal L5-S1 level approach is based on midline 3–5cm long approach dissecting the left side of the peritoneum from abdominal wall and stabilising the segment with two parallel-introduced titanium IVIS cages. The approach to L4-L5 and higher segments is performed through the similar short muscle splitting approach through the left side directly to the operated segments, introducing one single frontal plane cage. With this technique we have operated 40 cases, most of them in the course of primary surgical treatment, some as secondary revision surgery due to failed back syndrome. We are describing the technique, which is characterised with practically bloodless procedure(mean 150 ml blood loss from anterior approach).Stabilisation of L4-L5 and higher segments was supported with transpedicular fixation system. In our series we have encountered no specific intra and postoperative complications described earlier in the literature.Despite minimally aggressive approach the technique is demanding especially on L5-S1 level.In our opinion interrupted method of retraction of soft tissues and direct visualisation of the common iliac vein minimises the chances of complications. Radiological assessment performed in the period of 6 to 40 months postoperatively did not reveal any features of non-union and only minimal decrease of L5-S1 segment,which did not undergo posterior stabilisation. In our opinion minimally invasive approach to the lower lumbar spine with the use of interbody implants is effective method of fusion,with limited invasion into anatomical structures of the abdominal wall.

89 BIOMECHANICAL FINDINGS AFTER POSTERIOR RIB RELEASE IN TREATMENT OF STIFF THORACIC SCOLIOSIS P. Metz-Stavenhagen, F. Krämer, S. Krebs, O. Meier, H.J. Völpel Werner-Wicker-Klinik, Im Kreuzfeld 4, 34537 Bad WildungenReinhardshausen, Germany Purpose of the study: The efficiency of the posterior rib release (concave thoraco plasty) is to be shown by biomechanical examinations for the treatment of stiff thoracic scoliosis. Background: To receive a better raise especially of stiff thoracic scoliosis and to achieve a threedimensional correction of the accompaning thoracic deformity we developed in our clinic the concave thoraco plasty (CTP) and performed it so far at more than 600 patients successfully. The ribs are osteomized on the concave side as near as possible to the vertebra and after that fixed on the distraction rod through lateralisation and caudalisation. To measure the efficiency of the posterior release we used at 30 patients before and after the rib release intraoperatively a power measuring instrument. The distraction distance as well as the needed force was measured. Results: As it was to be expected a significantly lower effort had to be used to achieve the same level of distraction after rib release. The maximal possible distraction increased after CTP to 3 cm. A correction of the Cobb angle could be achieved from average 68° preoperative to 24° postoperative. The raise of the rib valley was average 4 cm. There were no complications at the 30 patients in this study. Conclusion: The through clinical and radiological examinations demonstrated very good results of the treatment of stiff thoracic scoliosis through CTP can be proved with these biomechanical examinations. This method can be recommended unanimously because of the very good cosmetic results, the negligible morbidity as well as our big experience. 90 STAGED SURGICAL TREATMENT OF JUVENILE IDIOPATHIC SCOLIOSIS M. Mikhailovsky, N.G. Fomichev, V.V. Novikov, A.S. Vasjura, M.N. Lebedeva Research Institute of Traumatology and Orthopaedics. Department of Spinal Surgery for Children and Adolescents. Frunze str. 17, Novosibirsk, 630091, Russia Surgical treatment of progressive idiopathic scoliosis in children of the first decade of life is a very difficult task which is solved in different ways: consequtive distractions (Tello, 1994), convex epiphysiodesis and dorsal instrumentation (Pratt et al, 1997), dorsal instrumentation only (Douglas et al 1999). The purpose of our investigation was to assess preliminary results of multi-stage surgical procedure including anterior release and convex epiphysiodesis (ARCE) and consecutive distractions. Since 1997 fifteen patients were treated – 9 girls and 6 boys. The mean age was 9.8 years (range 6–13). All children were Risser-0, all girls were premenarchal. ARCE was immediately followed by the first Harrington instrumentation (same-day surgery). The anterior growth arrest portion of the procedure averaged 5.3 spaces. The second distraction was performed in 9.5 months, the third in 8.7 months, the fourth in 9.8 months. All patients were braced postoperatively. Mean preoperative Cobb angle of primary curves (thirteen thoracic, two thoracolumbar) was 78.3 degrees. After the first stage of treatment 37.5 degrees (48.1%) correction was achieved. The loss of correction during 9.5 months of follow-up period averaged 15.7 degrees and was almost completely restored after the second distraction. In general in patients who were followed for more than two years (av-

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erage 28 months) 77% of correction was maintained. After first 7–8 months we noted marked acceleration of growth on concave parts of apical vertebrae bodies averaged 2–3 mm. Like the majority of other authors we noted the number of complications: seven bone fractures, three rod breakage, two cases of slight neurological signs. It made us to go away with Harrington instrumentation in favor of CD-Horizon in pediatric design. In all but one children Harrington rods were replaced by CD and the level of complications was sharply diminished. It is presupposed to perform consecutive distractions till age of puberty when definitive arthrodesis may be done. The main goal of treatment is to balance the concave and convex growth potentials of the scoliotic spine. We consider our first results to be optimistic. 91 THE AREA OF EPIDURAL FATTY TISSUE IN THE LUMBAR SPINE MEASURED ON MRI N. Mima, T. Endo, A. Nagamachi, S. Miyatake, M. Takahashi Mitoyo General Hospital, 708 Himehama, Toyohama-cho, Mitoyo-gun, Kagawa, Japan Introduction: Hypertrophy of epidural fatty tissue in the lumbar spine (HEFT) is sometimes observed and an causative factor of cauda equina syndrome, however, the diagnostic criteria of HEFT is not established. Although the ratio of the area of epidural fatty tissue in lumbar spinal canal (R) is important to access the diagnostic criteria of HEFT, there are few reports mention it. The purpose of this retrospective study is to investigate R to access the diagnostic criteria of HEFT. Subjects and methods: A total of 249 subjects (108 men and 141 women, mean age 57 years, range 20 to 85) were participated in this study. The areas of spinal canal; S and epidural fatty tissue; F were measured from T1-weighted axial magnetic resonance images of L3/4, L4/5 and L5/S1 disc levels by using NIH image software. The relationship between R (=F/S) and the age, sex and body mass index (BMI) were evaluated. Results: The mean R was not statistically different between sex in each disc level. There was no correlation between R and age or R and BMI. The mean R of L3/4, L4/5 and L5/S1 were 0.44±0.14, 0.46±0.14, and 0.57±0.18, respectively. Conclusion: These results indicate that aging, sex or BMI do not affect R. The normal range of R of L3/4, L4/5 and L5/S1 were 0.44±0.28, 0.46±0.28, and 0.571±0.36, respectively. 92 RESULTS OF SURGICAL TREATMENT OF THORACO LUMBAR SPINE FRACTURES J. Mineiro, L. Barroso, N. Moura, A. Rodrigues Gomes Department of Orthopaedic Surgery – Spinal Unit, Hospital de Santa Maria, Lisbon, Portugal Purpose of the study: Over the last few years our indications for surgery in trauma of the lumbar spine have been changing. Despite different reports on the management of this type of trauma, the treatment of lumbar spine fractures remains controversial. This study was set up to assess our results: on the surgical management of this condition in order to be able to make a retrospective analysis of the outcome of our patients at the beginning of the new century. The literature reports on the different surgical techniques from those maximally to the minimally invasive, but are patients really benefiting from all this new armamentarium? Methods: From 1991 to 1999, 60 patients were treated surgically for thoraco-lumbar spine fractures at the University Hospital of Santa Maria (38% of patients admitted to our unit with lumbar spine fractures). There were 42 men and 17 women with mean age

of 35.2 years. During the eight year period patients were admitted with different Injury Severity Score (ISS) and hospital stay changed during the different years due to the change in treatment policy in our department. As far as the etiology is concerned 21% were caused by working accidents, 39% by road traffic accidents, 9% by defenestration and 14% by falls. From the neurologic functional status 19% of patients presented with neurologic deficit, 5 frankel A, 2 Frankel C and 5 Frankel D. This group of patients sustained 80 fractures, 61 being at a single level and 19 at multiple levels (8 at two levels and 1 case of three level fractures). Among these fractures we had 1 case of a seat belt injury, 3 split fractures, 5 cases of fractures dislocations and 51 burst fractures that were distributed accordingly (Dennis A (3), Dennis B (36), Dennis C (8) and Dennis D (4). The indications for surgery in these cases were unstable burst fractures with more than 30% of vertebral body collapse or more than 30 degrees of angular deformity. The approach and surgical technique used in these cases was posterior instrumentation in 33 cases (four with posterior fusions and 12 with transpedicular bone graft), 14 combined posterior instrumentation and anterior fusion and 13 cases of anterior instrumentation and fusion. The type of instrumentation used in these cases was Dick’s internal fixateur in 23 cases, USS in 20, TSRH in four cases (two anterior and two posterior) and a Z plate in 13 cases. We assessed patients clinically for pain and work status according to Denis pain and Work scale and radiologically with plain radiographs and CT in a small group of patients on whom preoperative scans had been done. The radiological assessment was undertaken measuring the cobb angle in the AP and Lateral views, angular deformity of the fractured vertebra, saggital index, anterior vertebral body height on the lateral radiographs taken pre-op., post operatively and at follow up. Results: Pain score according to the Denis Pain Scale (table II) suggests that 60% of these patients were rated as good or excellent and according to the Denis Work Scale (table III) 7o% were back to the same job with a small percentage of patients requiring lifting restrictions. Radiologically, based on our previous research presented at a previous ESS meeting, we divided patients into three groups (Group A T12L1, Group B L2 and Group C L3L4L5) due to the fact that their fracture behaviour was different according to the different levels. Post operatively in group A it was easier to restore the vertebral body height and saggital alignment than in group C, where the vertebral body collapse was less severe but restoration of body height was more difficult. At follow up it was interesting to see that loss of saggital alignment was more severe in (lumbar spine) group C than in group A and the collapse happened at the disc level for reasons that are probably related to the type of injury mechanism. As far as the coronal deformity is concerned the scoliotic Cobb angle preoperatively was 4.6 and was reduced to 1.8 degrees post operatively. On clinical assessment at follow-up we could find no correlation between the degree of kyphosis and clinical outcome nor between the degree of canal compromise and neurologic functional status. Conclusion: As reported earlier, in this larger series of patients we could not find any correlation between Kyphosis and clinical outcome nor between neurologic deficit and canal compromise. At follow up Kyphosis was aggravated by collapse of the intervertebral disc and this fact was more pronounced in the lumbar spine and Saggital alignment and vertebral body height are easier to restore post operatively in the thoraco lumbar area. Although our indications for the use of anterior plating need to be reviewed this type of internal fixation showed a high rate of post operative collapse at the anterior column reconstruction. The combination of posterior instrumentation and anterior column reconstruction seem to give the best radiologic results at follow-up. Posterior minimally invasive procedures to restore saggital alignment seem to be a promising technique that is worth developing. It preserves the posterior muscle bulk and it allow removal of metalware under local anaesthetic.

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93 KYPHECTOMIES FOR THE TREATMENT OF LUMBAR KYPHOSIS IN PATIENTS WITH THORACIC MYELOMENINGOCELE J. Mineiro, S. Weinstein, J. Miguens, L. Barroso, A. Rodriques Gomes Department of Orthopaedic Surgery – Spinal Unit, Hospital de Santa Maria, Lisbon – Portugal, Department of Orthopaedic Surgery, Division of Pediatric orthopaedics and Spinal Deformity, The University of Iowa Hospitals and Clinics, Iowa City – USA Purpose: To assess the results of this type of procedures to correct such a deformity analysing as well the improvement on the methods of internal fixation over the last decades and functional outcome of the operations. Material and methods: Over a period of 18 years we have operated on 12 patients with severe lumbar kyphosis and thoracic myelomeningoceles. Seven of these patients were females and 5 males with a mean age of 5,7 year (from NB to 11 years old). The main indication for surgery was progressive deterioration of the lumbar kyphosis and skin ulceration at the apex of the saggital deformity. The number of vertebras in the curve were 8 on average (11–6) and the mean pre-operative angle of kyphosis was 113 degrees (180 to 68). The level of the myelomeningocele varied from T7 to T11. The surgical techniques used for correction of the deformity were – Lindseth 2, Dwyer 3 and Luque in 7 and the intraoperative blood loss ranged from 80 to 110% of their blood volume. Results: The mean follow-up of this series of patients was 7,2 years (14 to 1 year). The mean post-operative kyphotic angle was 33.5 degrees (83 to 5 degrees) that corresponded to 70% correction of the original angular deformity. As far as complications are concern 34% of the patients presented skin necrosis that required wound debridement, some with secondary procedures for wound closure and one case required a revision surgery for deassemble of the internal fixation and exposure of the Luque barr through the skin at the second week post-op. Despite a salvage procedure with a rotational skin flap the operative wound got infected and all metalware had to be removed. All together there were two cases of deep sited infection there had complete removal of internal fixation. Although most patients remained in the same functional group (depender sitters) there was an improved in their balanced sitting posture that left patients, parents and care takers happy with the result of the surgical procedure. Conclusion: Although kyphectomies are major surgical procedures for these young unfortunate children with a high incidence of complications, there seems to be a definite place for this type of operations in young patients with myelomeningocele and lumbar kyphosis. Segmental spinal instrumentation, whenever possible, brought an immediate stablilization of the operative correction that allowed early mobilization of the patients with no braces, whenever allowed by the soft tissues healing. Despite encouraging results, these are operations technically demanding that require a multidisciplinary backup not only from the surgical point of view but also from paediatric intensivists.

radiographs. The control group (CG) is 48 patients without any spine pathology, and 39 lytic spondylolisthesis (LS). There was no statistical difference for most of anatomic parameters between DS and CG, the only one that statistically differed was Incidence. We find no difference for Incidence between DS and LS. The sacrum of LS differs from LS as with CG. In DS the sacral morphology is of “ normal “type but Incidence is of LS type. We concluded that this high Incidence, with normal sacrum may result from pelvis, in the retro capital area that determine the anterior position of femoral heads. The posturals parameters of the DS demonstrate a very strong posterior tilting tendency. So, less forwards shearing strains at L5-S1 level. Why does the slipping occure at L4-L5 level? Is slipping a pathoanatomic or a pathomechanc phenomenon? Most previous studies focused on the role of facet joint alignment and reported a pronounced sagittal orientation. This pelvic conformation added to an increase of lever arm, and to an increase of backwards stress may induce strains at L4-L5 level, that participate in long term facet joint remodeling, and finaly late decompensation by the slippage of L5 under L4. This particular kind of pelvis illustrates the nececessity to now investigate the pelvic ring. 95 DEGENERATION OF THE INTERVERTEBRAL DISK IS RELATED TO VERTEBRAL ENDPLATE FRACTURES M. Mullender, M. Bonsen, J.H. van Dieën Amsterdam Spine Unit, IFKB, Free University, v.d. Boechorststraat 9, 1081 BT Amsterdam, The Netherlands It was indicated that a relationship exists between damage of the intervertebral disk and back pain [1, 2]. Yet, the cause of disk degeneration is still unclear. In vitro compression tests indicate that the intervertebral disk is much stronger than the vertebra itself. Hence, it was previously suggested that the initial cause of low back pain is endplate fracture, which may subsequently cause degeneration of the intervertebral disk[3]. The aim of this study was to investigate the relationship between disk degeneration and endplate fractures. Twelve human spines (fixated in a formaldehyde solution) were frozen and sawed in sagital sections (50 mm). In each section, both degeneration of the intervertebral disk and fractures in the vertebral endplates (between Th5 and S1) were quantified independently using a four grade classification (0–3). The scores of all sections from each specimen were averaged per level. The score for disk degeneration was correlated with the total score of the adjacent endplates using Spearman’s rho. Disk degeneration correlated significantly (rho=0.73, p<0.01) with endplate damage. In only 4% of the cases degeneration of the disk was found without evidence of endplate damage. These results indicate a high concurrence of the two types of damage. Hence, fractures of the endplate could indeed play an important role in the etiology of back pain. References 1. Vanharanta et al. (1987) Spine 12: 295 2. Grubb et al. (1987) Spine 12: 282 3. Dieën et al. (1999) Medical Hypotheses 53: 246

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THE PELVIS OF DEGENERATIVE SPONDYLOLISTHESIS J. Montigny, B. Boisaubert, G. Duval Beaupere, C. Marty, S. Sheik Ismael Hopital Foch, 40 rue Worth 92151 Suresnes, France

COMPLICATIONS OF PEDICLE SCREW FIXATION FOR DEGENERATIVE LUMBAR DISORDERS M. Murata, S. Akagi, Y. Nakahigashi, I. Kato, T. Saito Dept. of Orthopedic Surgery, Kansai Medical University, 10–15, Fumizono-cho, Moriguchi-city, Osaka, Japan

The aim of this study is to make an assessement of the pelvic parameters in degenerative spondylolisthesis (DS) at level L4-L5. Measures were carried out on 28 neutral standing lateral full spine

The surgical results of degenerative lumbar disorders underwent stabilization using pedicle screw (PS) were reviewed and the incidence of the complications for this procedure were studied.

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Materials & methods: Between January 1993 to March 1999, 67 patients were performed posterior decompression and fusion (posterolateral fusion in 40, posterior lumbar interbody fusion in 27) combined with PS system out of 208 patients performed posterior surgery for degenerative lumbar disorders. Of these, 31 had degenerative spondylolisthesis, 14 degenerative scoliosis, 9 spondylolitic spondylolisthesis, 9 recurrence of disc hernia, and 4 instability. Average age at the time of surgery was 57 years (28–83y.). There were 47 single-level and 20 multilebel fusions. Average follow-up period was 26 months (12–84m.). Results: Complications encountered were intraoperative pedicle fracture in 1, screw pulled-out in 1, screw cut-off in 1, displacement of rod with coupling failure in 2 cases, new radicular pain after reduction of listhesis in 1 case, nonunion required reoperation in 1 cases, infection in 1 cases. There were no vascular or nerve injury by misdirected screw. 4 patients complained of postoperative transient radicular pain or deficit due to nerve root traction during PLIF procedure. During the time of follow-up periods, breakage of screw and rod were not observed, however, 7 patients showed symptomatic adjacent level problems and 3 of 7 required additional surgery. Discussion & conclusion: Our conclusion was that PS fixation for degenerative lumbar disorders is an acceptable complication rate and neurogenic injury directly associated with an implanted device is unlikely. However, it should be emphasized that 10% of the patients showed newly developed symptomatic adjacent problem, especially frequent in the cases of degenerative scoliosis. 97 LONG TERM FOLLOW-UP OF THE ADJACENT SPINAL JOINTS AFTER CERVICAL SPINE FUSION S. Nazarian, V. Masselot Hôpital de la Conception.147 Boulevard Baille. F-13005 Marseille Introduction: This study aims to assess the long term result and adjacent degenerative changes in cervical spine fusion. Material and methods: 117 patients have been followed-up. 67 have been operated on for traumatic lesions and 50 for degenerative arthritis with radiculopathy or myelopathy. The following parameters have been analysed: age, sex, professional activities, primary disease, clinical symptoms, surgical procedure, fused segments, adjacent segments (discal height, osteophytes, slippage, dynamic instability, cervical curve). All the clinical parameters were evaluated, preoperatively, postoperatively and at last follow-up. Results: The mean age was 34 years in traumatic patients and 52.3 in degenerative ones. 58% of patients operated on for trauma developed degenerative changes. 78% of patients operated on for degenerative diseases developed additional degenerative changes. The relevant parameters in the occurrence of degenerative changes were the primary disease, age, anterior approach, kyphotic deformity, size and positioning of the anterior plate, previous state of the adjacent segments. Only 5.1% of patients required a reoperation. Discussion: The occurrence of secondary degenerative changes is reported in the literature. When fusion is required, the approach should be discussed. Modular fixation devices seem to be recommended. Conclusion: Degenerative changes following spine fusion are more frequent in old patients operated on for degenerative arthritis. A wrong positioning of the implants can induce an impingement and consequently degeneration. Modular plates should be developed and commonly used. Post operative rehabilitation should teach the patient how to mobilize more securely his cervical spine.

98 MORPHOLOGICAL PARAMETERS OF PEDICULAR DRILLING IN THORACIC AND LUMBAR VERTEBRAE S. Nazarian, C. Solari, P.O. Pinelli Hôpital de la Conception.147 Boulevard Baille. F-13005 Marseille Introduction: This study aims to identify the adequate entry point and direction of pedicular screws in each vertebra, on the basis of its anatomical specificities. Material and methods: Twelve specimens of each vertebra, from T1 to S1, were analysed on the basis of a converging drilling using a special probing awl. The entry point and direction were accurately identified. Results: The morphological similarities of the vertebrae led to individualize several groups: T1-T2, T3-T4, T5-T10, T11, T12, L1L2, L3-L4, L5, S1. The morphological landmarks allowing to find the entry point are: the upper edge of the transverse process, the laminar gutter of the neural arch, the lateral edge of the lower articular process, the tip of the mamillary process. The screw holes are drilled in an anterior and medial direction according to 30 to 5° with respect to the sagittal plane. Discussion: This study has identified the morphological landmarks of pedicular drilling. According to the chosen technique, the main parameter is the entry point. The direction is taken almost automatically by the awl, depending on the morphology of the cortex. The entry points proposed allow a slight convergence compatible with both the ancorage of the screw into the vertebral body and the respect of the muscles. Conclusion: The proposed parameters, very useful in regular aiming without computer assistance, can also be used in computer assisted surgery. In case of deformity, vertebral abnormalities should be taken in account.

99 THE BRANTIGAN ANTERIOR LUMBAR I/F CAGE. TWO YEARS RADIOLOGICAL RESULTS L.T. Nilsson, M. Geijer, P. Neuman, B. Lind Dept. of Orthopaedics and Radiology, Sahlgrenska Univ. Hospital, Göteborg, Sweden Background: The Brantigan carbon-fiber cage is designed to provide immediate and, by ingrowth of bone, long-term stability. Purpose: To report on especially the radiological results in a consecutive series with a minimum of 2 years follow-up. Material and methods: An anterior lumbar interbody fusion with a Brantigan cage filled with autologous bone was performed in 36 consecutive patients. Indication for surgery was intractable low back pain. The follow-up was performed by an unbiased observer, including CT-scan with reconstructions. Five patients declined the follow-up, one patient had a primary 360° fusion, seven patients were reoperated before the follow-up due to persistent back pain and suspected pseudarthrosis and one had died. Thus, 22 patients remained of which 17 had had previous lumbar operation. Surgery engaged one disc in 13 patients, two adjacent discs in 8 and three in 1. Results: 15 of the 22 patients thought they had improved with surgery whereas 7 did not. 6 patients were back working. Two patients had no CT reconstructions performed and in one patient the CT films had too many artifacts. In 12 of the remaining 19 patients was found an incomplete fusion of the bone columns in the Brantigan cage. Only in 7 was found a solid fusion. Conclusion: The pseudarthrosis rate in this series is very high as well as the number of reoperations. The number of patients in the study is small but still the results do not support the use of the Brantigan anterior lumbar I/F cage as a stand-alone device.

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PREVALENCE OF LOW BACK PAIN AND DESIRED TRAINING IN CONSTRUCTION WORKERS M. Nordin, D. Goldsheyder, S. Schecter, M. Halpern Occupational and Industrial Orthopaedic Center, Hospital for Joint Diseases Orthopaedic Institute, Mount Sinai NYU Health, 63 Downing Street, New York, NY 10014, USA

NEUROLOGICALLY INTACT FRACTURE-DISLOCATIONS OF THE THORACOLUMBAR SPINE: REPORT OF 10 CASES H.M. Özdemir, M. Arazi, T.C. Ögün, A. Sarlak, A. Kutlu Selcuk University Medical School, D, Department of Orthopaedic Surgery and Traumatology, TR-42080, Konya, Turkey

Introduction: Construction work is heavy manual labor. The purpose of this study was to evaluate the prevalence of low back pain in unionized mason/tenders in a metropolitan area, to evaluate perceived workload, and to evaluate preferred type of training. Methods: A survey was administered to 444 unionized mason/tenders. The survey included: demographics, prevalence of low back pain, visits to health care providers, job-related characteristics, and what type of training for the prevention of low back pain mason/tenders would prefer. A test-retest of the survey (n=30) showed moderate to excellent agreement (Kappa 0.36–0.81). Results: The response rate was 70.2% (n=311), 85% were males, average age was 39.9 (SD 9.2) years, and 78.3% had English as their native language. Thirty three percent of the mason/tenders had experienced low back pain during the past week, and 65% during the past year, 12% had missed work, and 18% had visited a physician. Most difficult working conditions related to the back pain were: continuing working while in pain, working near or at physical limits, working in awkward, bend and or twisted position, and working over head or away from the body. Ninety-one percent were interested in training, preferred as classroom (31%), on-site (36%) and video/website/brochure (33%) covering safety, proper work posture, tools and personal protection. Conclusion: Mason/tender population reported more than three times higher prevalence of low back pain than a general population, however, about similar healthcare consumption as the general population. The desire for prevention is high but the preferred type of training diversified.

Study design: Ten patients with neurologically intact thoracolumbar fracture-dislocations were studied retrospectively. Objective: To assess the postoperative results for this type of fracture-dislocations. Summary of background data: Fracture-dislocations of the thoracolumbar spine are mechanically unstable translational injuries and it is unusual for them to occur without any neurologic deficit. In the literature, neurologically intact thoracolumbar fracture-dislocations are presented as case reports or short series. Methods: Between 1987–1996, ten thoracolumbar fracture-dislocations were treated. The mean age of the patients were 42 years (range 28–59 years). Level of injury was thoracolumbar junction (Th11-L2) in 4 patients, lumbosacral junction (L5-S1) in 1 patient, lumbar region (L2–3) in 2 patients and thoracal region (Th6–9) in three patients. There were 8 bilateral and 1 unilateral facet dislocations. In three patients neural arc was in its anatomic position while anterior elements tranlated. Four of the patients did not accept surgical treatment and had a conservative follow-up and the remaining 6 were treated surgically. Results: The avarage follow-up was 34 (range 30–48) months. In the last examination operated group had no deterioration in their neurologic status and roentgenograms reveald no serious loss of reduction and solid fusion was observed. In the conservative group, all patients had varing degrees of pain, but they were all intact neurologically. Radiographically, the percent of translation was found to be decreased. However AP and Lateral plane deformities were increased. Conclusion: We obtained better results in surgically treated spinal fracture-dislocations in a small group of our patients. Even if there has been no neurological impairment during mid-term folllow-ups, mechanical instability may result in the long-term and we believe early open reduction and stabilization should be the way of treatment in these cases.

101 LONG-TERM RADIOLOGICAL CHANGES IN FEMORAL CORTICAL ALLOGRAFT USED FOR ANTERIOR LUMBAR FUSION J.P. O’Brien, P. Renton, A. Sarwat London Clinic Spinal Surgery Unit, 149 Harley St, London W1 N 2DE, UK Clinical experience with over 200 patients, over the past ten years, using femoral cortical allograft to replace the disc in anterior lumbar fusion has confirmed several important observations. Firstly, the rate of rejection is virtually nil. Early changes include the loss of line between donor and host bone as early as three to four weeks after surgery. There is no radiological difference whether the patient’s own bone or allograft chips are used to pack the allograft plug. At one year and beyond, there is filling in of the interbody space behind the donor bone with host bone, thus preventing any risk of posterior migration of the allograft plug. Over the first twelve months, there is some subsidence of the allograft into host bone, sometimes several millimetres in extent. Axial views show important changes up to ten years after insertion. There is gradual erosion of the allograft by host bone, both at the external and internal diameter so that, ten years after insertion, there is the merest shell of donor bone identified and the rest clearly replaced by host bone. Unfortunately, biopsy samples to co-relate with the radiological films are not available. For reasons of cost, mechanics, biological behaviour and ease of shaping before insertion, femoral cortical allograft has provided an excellent long-term disc replacement.

103 LENKE’S NEW SCOLIOSIS CLASSIFICATION SYSTEM. COULD IT BE PROPERLY ADAPTED FOR ROUTINE SCOLIOSIS FOLLOW-UP EVALUATION? M. Ogon, K. Giesinger, H. Behensky, C. Wimmer, M. Krismer Department of Orthopaedic Surgery, University of Innsbruck, A-6020 Innsbruck, Austria Background. A new classification system for idiopathic scoliosis has recently been developed by Lenke et al. Curve Type is determined on coronal radiographs with additional bending films to identify structural curves. However, during routine follow-up evaluation of idiopathic scoliosis bending films are usually not justified. Objective. This study was performed to determine the ability of the new system to classify idiopathic scoliosis in curve types (1–6) and lumbar modifiers (A,B,C) on coronal radiographs in the absence of bending films. The aim was to determine whether the new system of Lenke et al. could be adapted for scoliosis classification in a non-operative, routine scoliosis follow-up setting. Methods: Posteroanterior full-lenght radiographs of 76 patients with idiopathic scoliosis were reviewed inependingly by four observer. All curves were classified according to Lenke in type 1–6 with the lumbar modifier (A,B,C) determined if applicable and ac-

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cording to King in type 1–5 (or as I not applicable II for thoracolumbar or lumbar curves). Classification was repeated 3 weeks later. Kappa statistics were performed to determine the inter- and intraobserver reliability of the Lenke and the King classification system as applied in this study. Results: In this setting, the interobserver reliability of Lenke’s system was sligtly heigher (Kappa 0.53) compared to the King system (Kappa 0.45). The intraobserver reliabilities of both classification systems were similar (Lenke: Kappa 0.78; King: Kappa 0.79). Conclusion: Even without bending films, Lenke’s system is at least as reliable as the classic King system. 104 PYODERMA GANGRENOSUM AS SEVERE COMPLICATION OF ANTERIOR/POSTERIOR LUMBAR FUSION M. Ogon, N.T. Sepp, R. Biedermann, C. Wimmer, H. Behensky Department of Orthopaedic Surgery and Department of Dermatology, University of Innsbruck, Anichstrasse 35, A-6020 Innsbruck, Austria Objective. To emphasis the clinical value of knowing pyoderma gangrenosum. Methods and results: A case of a forty-two year old man is described who underwent anterior-posterior spinal fusion for spondylolisthesis L5/S1. At the 6th postoperative day erythematous papules spread concentrically around several wound sides. There was a discharge of pus, as well as fever (38.5° C), leukocytosis (22.0 G/l), and an increased CRP level (14.4 mg/dl (norm: >0.5 mg/dl)). Severe infection was assumed. However, antibiotic therapy failed and cultures remained sterile. At this time the ulceration was deep, sutures fall apart and the peritoneum was seen in a wide area. The called dermatologist diagnosed the typical picture of a severe pyoderma gangrenosum: ulceration’s that extends peripherally with undermined border and surrounding areola of erythema, the border well defined and deep erythematous to typical blue or violaceous in colour. Corticoid therapy (120 mg methylprednisolon) for 6 weeks stopped further progression. The wide defect of the abdominal wall was operatively closed by secondary sutures and the patient recovered fully within the next 2 months. 18 months follow-up showed no signs of recurrence. Discussion. Pyoderma gangrenosum is a rare ulcerative, cutaneous condition that can simulate wound sepsis after surgery. The local appearance of ulcerated lesions with pus-covered centers and the progressive wound ulceration, as well as the general symptoms with possible fever and leukocytosis may mislead the surgeon to the diagnosis of deep wound infection. However, adverse to the essentials of infection care, pyoderma gangrenosum requires high doses of corticosteroids or even additional immunsuppresive drugs like cyclosporine A and azathioprine. In the absence of any specific laboratory test or a specific histopathology, the clinical picture of the characteristic ulcerations with undermined violaceous edges is the cornerstone for the diagnosis of this disease. Conclusion: Knowledge of the typical clinical picture and awareness of pyoderma gangrenosum as rare, but severe, postoperative complication in spine surgery should avoid delayed onset of proper therapy. 105 LUMBAR DISC HERNIATION IN THE ELDERLY M. Ogushi, S. Akagi, T. Saito, I. Kato, K. Sasai Department of Orthopedic Surgery, Kansai Medical University, 10–15 Fumizono, Moriguchi, Osaka, Japan The clinical and pathologic characteristics of lumbar disc herniation were investigated retrospectively in the elderly. Material: We

reviewed 169 consecutive patients over 60 years of age who underwent decompressive surgery for degenerative lumbar disease between 1985 and 1996 at Kansai Medical University. Out of these patients, 23 were diagnosed as having disc herniation as a main cause of nerve root compression based on the preoperative and intraoperative findings. There were 15 men and 8 women. The mean age at the operation and the mean follow-up period were 67.3 years and 23 months, respectively. Results: Preoperatively, severe unilateral leg pain was a predominant symptom, and 13 patients were non-ambulatory because of leg pain. The straight leg raising test was positive in 15 patients (65%), and the femoral nerve stretching test was positive in 6 patients (26%). Impairment of motor function and sensory deficit was observed in 87% and 78%, respectively. The surgical outcomes were satisfactory, being evaluated as excellent in 11 patients and good in 12. Four (17%) of the 23 patients had disc herniations at the L2/3 or L3/4 level. Sequestered herniation with or without migration was observed in 15 (65%) patients. Of 14 specimens of sequestrated fragment examined histologically, 8 (57%) contained cartilagenous or bony end plate with anulus fibrosus and/or nucleus pulposus. Conclusion: Our results indicated that in disc herniation in the elderly severe leg pain, disturbing their activities of daily life, is a predominant symptom. If conservative treatment fails, operative treatment should be considered, resulting satisfactory outcome. In the management of lumbar disc herniation in the elderly, the high incidence of more cephalad and lateral herniations should be considered. In addition, sequestrated and migrated type herniation including the end plate is frequent. 106 THE OLERUD CERVICAL FIXATION SYSTEM IN C1-C2 INSTABILITY C. Olerud, M. Cornefjord, T. Henriques Department of Orthopedics, Uppsala University Hospital, Uppsala, Sweden C1-C2 fusion is indicated instability caused by fractures and nonunion of the dens, rheumatic subluxation, ligament laxity, and congenital deformity. Traditional Gallie fixation with cerclage wire and a structural bone graft gives poor stability with high failure rate. By adding transarticular C1-C2 screws the non-union rate drops to acceptable levels. However, the drawbacks with structural bone graft and sublminar wire remain. The C1-Claw Device was developed to improve C1-C2 fixation without relying on structural bone graft or intraspinal instrumentation. The aim of this paper is to report the results of a consecutive series of C1-C2 fusion with the C1- Claw Device from our institution. The series consists of 26 consecutive patients (14 women) with a mean age of 73 (37–93) years. The indications were dens fractures in 18 patients, rheumatoid C1-C2 instability in 6, dens non-union in one and Os Odontoideum in one. The patients have been followed by an independent observer (MC) clinically and with plain radiographs for 15 (3–27) months. The radiographs were evaluated for signs of secondary displacement, instrument failure, and fusion healing. There were no neuro-vascular complications. Nine patients have been followed for 6 to 12 months and eleven patients for 12 to 27 months. All are healed without secondary displacement. Posterior C1-C2 fusion with the C1-Claw Device seem promising. No serious complications have been encountered. The stability of the implant obviates the need for a structural bone graft and still results in a high frequency of fusion healing without secondary displacement.

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A MODERN APPROACH TO POSTERIOR FIXATION OF THE CERVICAL SPINE C. Olerud Department of Orthopedics, Uppsala University Hospital, Uppsala, Sweden

THE GRAF STABILISATION SYSTEM FOR DEGENERATIVE DISC DISEASE: RESULTS IN THE FIRST 50 PATIENTS AT AN AVERAGE FOLLOW-UP OF OVER 7 YEARS K. Pande, A. Gardner The Essex Spine Centre, BUPA Hartswood Hospital, Brentwood, Essex, UK

Posterior fixation of the cervical spine is indicated in rheumatoid arthritis, ankylosing spondylitis, tumors, or deformities. Traditional techniques with wiring or lateral mass plates give poor stability, with loss of fixation and healing disturbances. We have developed a rod-based posterior fixation device for the cervical spine. Pedicle-, lateral mass-, and facet screws, as well as hooks or sublaminar wires can be combined. The screws are positioned before the rods are mounted. Additional anchors can be added after the main construct is assembled. The system can be fitted to short and long fixations or extended to the occiput. There is a special C1-C2 fusion device. In biomechanical tests the system has proven more stable than lateral mass plates. An independent observer safety and efficacy study of the first 30 cases was done. A comparison was made in rheumatoid subaxial subluxation between 16 patients with treated with the new system and 10 patients treated with traditional plate fixation. The rod system gave the same low incidence of fixation failure as 360 degrees fixation but with shorter operation time whereas patients treated with one-side-only plate fixation showed higher incidence of failure. A prospective study of 26 patients treated with posterior C1-C2 fusion has been conducted. The results indicate good primary stability. No secondary displacement has occurred, the incidence of union is high, and no patient has been reoperated. The conclusion is that the new fixation system is versatile and useful for most posterior fixations of the cervical spine. 108 SF-36 ON SCIATICA PATIENTS: MEASURING QUALITY OF LIFE ON LUMBAR DISC HERNIATION R. Padua, Lupparelli, E. Ceccarelli, R. Bondi, L. Aulisa Divisione di Ortopedia-Ospedale San Giacomo, Rome- Italy Introduction: A pre-operative patient-oriented study was conducted on individuals with symptomatic lumbar disc herniation undergoing standard discectomy to compare their health status with that of an age-matched healthy sample. Material and methods: There were 83 patients (46 males and 37 females), mean age 46.20±13.98 SD years, affected by lumbar disc herniation as confirmed by CT or MR. Clinical radiculopathy distribution was: unilateral L4 in three patients; bilateral L4 in one; unilateral L5 in twenty-six; bilateral L5 in two; unilateral S1 in thirty; bilateral S1 in two; unilateral L4 + L5 in one; unilateral L5 + S1 in twelve; bilateral L5 + S1 in six. The SF-36 questionnaire (official Italian version) was administered preoperatively and the results were compared with those of an age-matched healthy sample (n=351) published in the Literature. One-way ANOVA was used for statistics (P <0.05). Results: The SF-36 domain scores for the group affected by disc herniation and for the healthy group were respectively the following: PF 40.20±26.87 and 88.69±14.93; RF 8.73±21.18 and 81.71±30.27; BP 19.67±16.22 and 75.26±24.07; GH 57.53±18.13 and 66.45±17.49; VT 36.31±19.75 and 63.36±18.19; SF 43.24±21.64 and 78.37±20.38; RE 22.06±35.04 and 79.20±33.58; MH 43.76±22.05 and 67.76±18.18. Significance was P <0.000 for all domains. Conclusion: Symptomatic lumbar disc herniation seems to significantly affect patients’ perception of their own health. A better knowledge of the health status changes induced by disc herniation might help further define the indications to surgery.

Introduction: The Graf Stabilisation System (GSS) has been criticised for lack of reports of long-term outcome. Mixed results have been reported at early follow-up generally with poorly defined indications, which are now much clearer. Aim of the study: To report a long term prospectively studied and independently assessed audit of the first 50 cases of GSS. The 2year follow-up results have previously been published (Grevitt et al 1995). Material and methods: The first 50 consecutive patients who underwent GSS, performed by a single surgeon (AG) were evaluated using a postal questionnaire, which included Oswestry Disability Score (ODS) and Distress & Risk Assessment Method (DRAM). Additional information was obtained from the hospital notes and radiographs at last review. Results: Data was available on 40 patients (10 nonrespondents). For the final analysis, 31 patients with GSS in situ were considered after excluding patients who had subsequent fusion/removal of GSS (n=9). The average age and follow-up was 41.8 yrs (17.2–60) and 7.4 yrs (5.6–8.5) respectively. Excellent and good subjective result was reported in 62% of patients. 61% reported significant/total relief of low back pain and 77% never or occasionally used analgesics. The mean ODS, pre- and post-operatively was 59±10% and 37.7±14.0% respectively. Conclusion: The results of this study suggest that the beneficial effect of the GSS is sustained in the longer term. A study of the condition of the 10 non-responders when last seen indicated no particular bias of the results. 110 DECISION MAKING IN METASTATIC SPINAL DISEASE S. Papastefanou, V.R. Rapuri, C.G. Greenough, S. Marks Department of Orthopaedics & Neurosurgery, Middlesbrough Gen. Hospital, UK Background data: The operative management of metastatic spinal disease remains palliative aiming at pain control and neurology improvement. Decision-making is difficult and open to debate. The Tokuhashi-score has been proposed as a useful instrument of the prognosis for radical surgery. Aim: To audit prospectively the influence of the Tokuhashi-score in the decision making process, during the management of patients with metastatic spinal disease. Background: Prospective audit of consecutive patients, for which a direct or second opinion was requested from the senior author. Epidemiological data on previous and current treatment and survival rates were analysed. Results: 24 patients with mean age of 60.7 years (range 39–88) were included in the study. These patients were managed between May ‘97-Feb ‘00. Half of them had a poor preoperative status at the time of the surgery (PS=30%=0). For the duration of the study 12 patients remained alive. 20 patients had an operation, while 4 were refused. 15 patients had improvement of pain, while 8 out of 17 had improvement of neurology. 2 died in the peri-operative period. Tumour excision was seldom requested as a direct result of the Tokuhashi-score used in the pre-operative assessment. The pre-operative patient status tended to be more influential for the operative outcome. Our numbers were low to make a statistical significance yet.

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Conclusion: The Tokuhashi-score influenced the decision making process in the management of metastatic spinal disease. A less radical approach can be equally effective in achieving the palliative result of surgery. 111 HYDROXYAPATITE IN ANTERIOR CERVICAL FUSION: A TWO-YEAR FOLLOW UP BY QUANTITATIVE CT L. Papavero, R. Zwönitzer, I. Burkard Department of Neurosurgery, Eppendorf University Hospital, Martinistrasse 52, 20246 Hamburg, Germany Aim of the study: The change of the hydroxyapaptite (HA) mass in Tibon® (titanium cage + a bovine HA-core augmented with vertebral bone marrow) was investigated by quantitative Computed Tomography (qCT) in a prospective study with minimum two year follow-up. Methods: Eighty-six patients underwent anterior cervical fusion (112 implants) between 1995 and 1999. Fifty implants were evaluated postoperatively by an especially designed qCT. The data at 3 days, 6,12 and 24 months after surgery of the first 30 implants are presented. Two mm axial slices of Tibon®, the adjacent vertebral bodies and of a neck-like polyethylene dummy containing a HAblock with known density (800 mg/ml) were performed. The relative change of the HA-mass at 6, 12 and 24 months was plotted slice by slice versus the 3 days data. Results: Six months after surgery the vertebral bone adjacent to the implant showed 37% increase of the HA-mass vs. 11% increase in the peripheral area of the HA-cylinder and 5% in its most distant portion from the vertebral endplates. After 12 months the relative increase of HA-mass in the vertebrae declined (+21%) whereas climbed homogenously in the core of the implant up to 25%. At 24 months the relative change of HA-mass corresponded roughly to the baseline (<+4%) in the vertebral trabeculae and reached the steady state (+ 27%) in the core of the implant. Changes were significant (p<0.001). Conclusion: The changes of HA-mass mirror with high probability the experimentally shown layering of autologous bone on the HA-trabeculae. 112 ALIF VERSUS PLIF: A ROENTGEN STEREOPHOTOGRAMMETRIC ANALYSIS (RSA) OF SPINAL ARTHRODESIS D. Pape, E. Fritsch, F. Adam, K. Müller, D. Kohn Orthopedic Department, University of Homburg, Kirrbergerstrasse, 66421 Homburg/Saar, Germany Introduction: Spinal fusion with an internal fixator and insertion of interbody cages is an established method, although surgical approach and cage design are disputed. Interbody cages are said to maintain disc height depending on cage design, presence of supplementary posterior fixation and mineral bone density. Using the precise RSA method, stability of the fused segments in patients with spinal stenosis and spondylolisthesis were prospectively investigated. Materials and methods: 8 patients with spinal stenosis L4/5 underwent a one-stage posterior decompression and stabilization with 2 rectangle carbon-fibre Brantigan PLIF-cages. 8 patients with low-grade spondylolisthesis L5/S1 underwent a two-stage posterior and retroperitoneal anterior fusion with insertion of an oval-shaped carbon-fibre Brantigan ALIF-cage. At surgery, tantalum markers were implanted into the adjacent vertebrae. All patients were examined by RSA after the first/second operation and every 3 months.

Results: 3 months after surgery the mean intervetebral mobility determined by RSA was below the accuracy of the RSA-method (3/10 mm). Within the first 6 month after surgery, ALIF-cages showed a mean subsidence of 0.9 mm along the vertical axis. PLIF-cages showed a significant ongoing settlement of 1.4 mm on average within the first 12 months after surgery. Both cages showed persisting micomotions in the direction of insertion. Conclusion: Although bony fusion could be achieved with both cages 3 month after surgery, settling around PLIF-cages persisted longer compared to ALIF-cages. The smaller contact area of the bone-implant interface in the PLIF-procedure might lead to higher axial compression forces promoting the persisting subsidence of PLIF-cages. 113 MONOSEGMENTAL CIRCUMFERENTIAL FUSION WITH CAGES AND TRANSLAMINAR SCREWS IN MANAGEMENT OF LOW BACK PAIN P.W. Pavlov, M. Spruit, P. Anderson, W. Jacobs Sint Maartenskliniek, P.O. Box 9011, 6500 GM Nijmegen, The Netherlands Study design. A prospective outcome study of 23 consecutive patients treated with monosegmental circumferential fusion for degenerative conditions of the lumbosacral spine. Objectives. To evaluate the clinical results after a monosegmental fusion and the performance of fusion by cages, filled with autologous bone and supplemental translaminar screw fixation. Methods: From October 1996 to June 1997 23 consecutive patients were surgically treated with ALIF and supplemental translaminar screw fixation. The level of fusion was defined by radiological changes, MRI and discomanometry. All the patients were operated by the same surgeon and evaluated by independent observer. A titanium cage (SynCage) filled with autologous cancellous bone was inserted between the vertebral bodies using an anterior retroperitoneal approach. Translaminar facet screws, according to the technique of Magerl, were used for supplemental fixation. An objective assessment of outcome was obtained by the Visual Analog Scale (VAS) for pain and the Oswestry Disability Index. The fusion was evaluated on flexion/extension X-rays and a possible subsidence of the cages by two independent radiologists. Results: The results at minimal 24 months show no occurrence of subsidence and no instability of the fused segments on flexion/extensions X-rays. The Oswestry score fell from 43.4% pre-operatively to 1.8% at 24 months after surgery. The VAS-score improved from 6.6 preoperatively to 0.3 at 24 months. Conclusion: Clinical results with 360° fusion using SynCage and supplemental translaminar screw fixation are most encouraging. 114 CT SCAN EVALUATION 2 YEARS AFTER L5-S1 LAPAROSCOPIC ALIF F. Pellise Urquiza, O. Puig, A. Rivas, J. Bago, C. Villanueva Hospital de Traumatologia Vall d’Hebron. Pg Vall d’Hebron 119–129, 08035 Barcelona, Spain Objectives: To assess the fusion rate and the clinical outcome after L5-S1 laparoscopic ALIF using carbon fiber cages as stand alone devices, in patients with more than 2 years of follow-up. Material and methods: We evaluated 12 patients with a mean age of 36.5 years, in whom an endoscopic L5-S1 ALIF using stand alone carbon fiber cages was performed before February 1998. Clinical evaluation was carried out prospectively by use of 3 selfevaluation scales (Visual Analogue Scale, modified Prolo scale and Wadell Disability Index). Radiological evaluation was carried

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out by an independent radiologist using plain X-rays, dynamic flexion-extension films and CT scans. The L5-S1 segment was considered to be fused when complete trabeculation connecting both end-plates was observed on at least 3 consecutive CT slices. Results: 1. Clinical Status – After a mean follow-up of 35.4 months the clinical condition of our patients was significantly better than their preoperative status: VAS preop 7.18, VAS f-up 2.49 (p= 0.00); Prolo preop 5.80, Prolo f-up 8.50 (p=0.02); WDI preop 53.25, WDI f-up 12.88 (p=0.01). 2. Fusion – L5-S1 mobility did not exceed 50 in any dynamic study of the 12 patients. The CT scan at 24 months after surgery showed fusion in 2 patients. In 3 patients 1 or 2 CT slices showed trabeculation connecting both end-plates. In 7 patients no slices showed trabeculation connecting both end-plates. The overall CT scan fusion rate at 2 years followup was 16.6%. The 2 scans performed at 3 years of follow-up have not yet demonstrated fusion. Conclusion: In spite of the good clinical evolution, CT study shows that 2 years after endoscopic L5-S1 ALIF using stand alone DePuy-Acromed laparoscopic carbon fiber cages the fusion rate is unacceptably low. 115 MORBIDITY OF SEGMENTAL SPINAL INSTRUMENTATION (SSI) AND FUSION FOR CHILDREN WITH CEREBRAL PALSY G. Pender, R.J.B. Sakkers, H.E.H. Pruijs UMC,KE 04.140.5, Postbus 85090, 3508 AB Utrecht, The Netherlands Introduction: Scoliosis secondary to cerebral palsy often is severe and progressive. Despite the technical improvements for spinal fusion and the more rapid postoperative mobilisation the chance of complica-tions remains very high. The aim of this retrospective study is to analyse the operation results and complication rate of spinal fusions. Methods: Since the early eighties a neuromuscular team is involved in the preoperative examination of children with secondary scoliosis. Two children were found not to benefit of surgery. Fiftyeight children wereevaluated. The method of choice was posterior spinal fusion by Luque technique. Only in severe curvatures an anterior fusion was added. Results: The folluw-up ranged from one till 14 years (mean 3.0 years). The average age at the time of the operation was 13.4 years (range 3.8–19.1). On average the children lost 60% of there total blood volume. Average duration of hospitalisation was 12.9 days (range 6–55). Assisted mechanical ventilation was needed for an average of 0.8 days (range 0–22). There were 76 complications in 36 patients (62%) Discussion. Despite the technical improvements for spinal fusion and the more rapid postoperative mobilisation the chance of complica-tions remains very high, as is reported in the literature. The main factors in outcome were the age of the child and the gender. In young boys a severe progression can occur after spinal fusion. In this group a different surgical technique should be used. Conclusion: Spinal fusion in severe scoliosis in CP children is still accompagnied with a high complication rate. With secure preoperative planning in a multidisciplinary team, a good result can be obtained. In severe scoliosis anterior spinal fusion must be added, espescially in young children.

116 EVALUATION OF CURVE PROGRESSION IN IMMATURE IDIOPATHIC SCOLIOSIS I. Petcu1, A. Cretu2, R. Topa3 1”Recuperare” University Hospital, 14, Pantelimon Halipa Street, IASI 6600 Romania; 2”Recuperare” University Hospital, Department of Orthopaedic Surgery, 14, Pantelimon Halipa Street, IASI 6600 Romania; 3”Recuperare” University Hospital, Department of Rehabilitation – Kinesitherapy, 14, Pantelimon Halipa Street, IASI 6600 Romania Introduction: In the early detection of spinal deformities, a large number of patients with small idiopathic scoliosis are being seen for evaluation and treatment. An evaluation of the factors that influence the natural progression of these curves is essential in planning a treatment program. Methods: The cases of 180 patients with idiopathic scoliosis were reviewed between 1996 and 1999. From theses, only 120 patients were initially curve measuring from 5 to 30 degrees. The patients were followed either to the end of skeletal growth or until the curve progressed. The criteria for progression were: an initial curve that increased at least 10 degrees with a final curve greater than 20 degrees and an initial curve between 20 and 30 degrees that increased by 5 degrees or more. Results: The progression of the curve was found at forty-two patients (35 per cent). The incidence of curve progression was correlated with the patient’s age at presentation, the magnitude and pattern of the curve, the Risser test, Harrington factor, rotational proeminence and the patient’s sex and menarchal status. Using the positive correlation that were found, between progression of the curve and the magnitude and pattern of the curve, chronological age and the Risser test cross correlation were calculated in an attempt to determine a prognosis factor. Conclusion: This study has pointed out the factors related to progression of small idiopathic scoliotic curves during growth. The resulting graphs may help in the decision – making process, especially when advising the family and planning continuing care. 117 LOW BACK PAIN: AN EPIDEMIOLOGICAL SURVEY A. Peveraro, G. Magliano, G. Giustetto Ospedale Civilie di Asti, U.O.A. Ortopedia e Traumatologia, V Botallo 2, 14100 Asti, Italy Low back pain is a common complaint in patients of various age and activity, often observed by the family doctor earlier than the orthopaedic surgeon. For this reason it’s sometimes difficult to appreciate the real prevalence of a disease which, although usually mild, causes a massive loss of working days in the overall population. In order to quantify its importance, the Authors performed an epidemiological survey on a conspicuous population specimen. 162,670 patients have been surveyed for one month with regard to pain complaints referred to the low back. During the observation period 1464 patients saw their doctor for low back pain, with an incidence that states 10.8% on an annual basis. A slight female prevalence has been observed, while age distribution showed peak incidence in the middle age. Results concerning age, sex, work and leisure activity were compared with the diagnoses achieved after clinical and instrumental examinations: most frequent aetiologies involved arthritis, muscle/ligament pathologies, facet syndrome and discal herniation, with good correspondence with previous studies. Other useful informations came by evaluating the frequency of similar episodes in the patient’s history, and recording the number and frequency of diagnostic procedures he underwent. Low back pain is a common disease, whose generally benignant evolution must be known: only a small number of patients will re-

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quire prolonged therapy, and surgical treatment will be envisaged in an even smaller percentage. To be aware of this allows to avoid unjustified increases in health care expenses, and will spare the patients a good deal of worries. 118 COMPARISON OF THE ELECTROMYOGRAPHIC ACTIVITY OF THE EXTERNAL OBLIQUE MUSCLE AT DIFFERENT LOCATIONS M. Pietrek, A. Sheikhzadeh, M. Hagins, M. Nordin Occupational and Industrial Orthopaedic Center, Hospital for Joint Diseases Orthopaedic Institute, Mount Sinai NYU Health, 63 Downing Street, New York, NY 10014, USA

thesis was installed to the injured segment and this tested again. Range of motion (ROM) was analysed using an optoelectronic measuring device. Results: A significant increase of ROM in each loading case was seen after transsection of the capsular ligaments when compared to ACFP (p=0.0016 for flexion/extension, p=0.00021 for bending, p=0.00045 for rotation, student Newman-Keuls test). Additional posterior fixation led to a significant decrease of ROM in each loading case (p=0.00021 for flexion/extension, p=0.0031 for bending, p=0.0025 for rotation, T-test). Conclusion: Facing the limitations of biomechanical studies, ACFP is sufficient for flexion-distraction injuries unless the capsular ligaments (and facets) are not injured. 120

Introduction: Despite evidence for a selective activation of the muscles of the lateral abdominal wall through anatomical and myoelectrical studies, biomechanical models estimating spinal loads typically use EMG data of a single electrode location to represent the entire muscle. Therefore, the purpose of this study was to compare the EMG activity of the external oblique (EO) at four different locations during isometric exertions in two planes. Methods: Thirteen healthy subjects were tested during 26 randomized isometric flexion, extension, and rotation tasks with four levels of exertion, using a triaxial lumbar dynamometer. EMG activity of the EO was measured by small surface electrodes placed at four locations on one side halfway between iliac crest and rib cage. To ensure correct electrode placement, fiber orientation of the EO had been measured in four cadavers beforehand, and the location of each electrode was confirmed by ultrasound imaging. Repeated ANOVA was used to determine the effect of exertion level and location on EMG activity. Results: Statistical analysis demonstrated a significant effect of level of exertion on EMG activity (p<0.001). However, there were no significant differences in EMG activity between the four locations in all tasks and planes (p<0.05). Conclusion: For biomechanical modeling utilizing isometric EMG, the use of a single electrode location seems to be sufficient to determine the activity of the entire muscle. However, as the muscles of the lateral abdominal wall with their widespread origins and insertions demonstrate marked changes in fiber direction from ventral to dorsal, multiple force vectors should be implemented in future models. 119 BIOMECHANICS AND STABILISATION IN SIMULATED FLEXION-DISTRACTION INJURIES T. Pitzen, C. Lance, D. Goertzen, M. Dvorak, D. Barbier, W.I. Steudel, T. Oxland Neurochirurgische Klinik, Universitätsklinik des Saarlandes, 66421 Homburg, Germany

THE INFLUENCE OF CENCELLOUS BONE DENSITY ON LOAD-SHARING IN HUMAN LUMBAR SPINE. A COMPARISON BETWEEN AN INTACT AND SURGICALLY ALTERED MOTION SEGMENT T. Pitzen, K. Pedersen, F.H. Geisler, D. Matthis, H. Müller-Storz, W.I. Steudel Neurochirurgische Klinik, Universitätskliniken des Saarlandes, 66421 Homburg, Germany Objective. Aim of the study was to compare load-sharing in compression in an intact and surgically repaired lumbar spine motion segment L3/4 depending on bone mineral density (BMD). Methods: Six cadaveric human lumbar spine segments (three L2/3 and three L4/5) were taken from fresh human cadavers. The intact segments without preload and following instrumented stabilisation (Posterior lumbar interbody fusion using two titanium cages and posterior screw-rod fixation) were compared in testing of axial compression (600 N). These results were compared to a finite element model (FEM) simulating the effect of identical force on the intact segments and the segments with constructs. Results: The predictions of both the intact and surgically altered FEM were always within one standard deviation of the mean stiffness as analysed by the biomechanical study. Thus, FEM was used to analyse load-sharing under compression in an intact and surgically repaired human lumbar spine segment model using different E–modulus for cancellous bone of the vertebral bodies. In both the intact and surgically altered model, 89% of the applied load passed through the vertebral bodies and the disc if an E–modulus of 25 MPa was used for cancellous BMD. Using 10 MPa–representing soft, osteoporotic bone–this percentage decreased in both but increased using 100 Mpa in both models. Conclusion: Reconstruction of both the disc and the posterior elements with the implants used in the study recreates the ability of the spine to act as a load-sharing construct in compression for each BMD analysed. 121

Objective. The purpose of this study was first to quantify the stabilising effect of anterior cervical fusion and plating (ACFP) in various grades of simulated flexion/distraction injuries in human C-spine. Second, to evaluate the effectiveness of additional posterior screw-rod stabilisation in these injuries. Summary of background data As well biomechanical and clinical data are quite confusing about appropriate method for spinal fixation in cervical flexion/distraction injuries. Study design Biomechanical approach using fresh frozen human cervical C-spine segments C4-C7. Material and methods: Eight fresh frozen human cervical spine segments C4 – C7 were loaded using pure moments of 1.5 Nm in flexion/extension, axial rotation and lateral bending in the intact state and following ACFP including stepwise cutting of the posterior ligaments in C 5–6. Finally, a posterior screw-rod osteosyn-

A VALIDATED FINITE-ELEMENT MODEL OF HUMAN CERVICAL SPINE: DESCRIPTION AND FIRST APPLICATIONS T. Pitzen, H.J. Wilke, D. Matthis, H. Müller-Storz, D. Barbier, W.I. Steudel, K. Pedersen Neurochirurgische Klinik, Universitätskliniken des Saarlandes, 66421 Homburg/Saar, Germany Objective. Purpose of this study was to generate a finite element model (FEM) of human c-spine to be used for first analysis on new implants. Methods: CT–data of a human c-spine C4–7 were used to generate a three-dimensional, anisotrophic, linear FEM. Based on the in-

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tact model (FEM 1), two additional models were generated: FEM with simulation of anterior cervical fusion and plating using monocortical (FEM 2) and bicortical (FEM 3) screws. Loading of each FEM was simulated using pure moments of±2.5 Nm in flexion/extension, axial left/right rotation and left/right lateral bending. Range of motion (ROM) was calculated. The results were compared to the results of a parallel in–vitro study. The results obtained by FEM 1, 2, 3 were always within one standard deviation of the results of the corresponding part of the in–vitro study and are listed in Table 1. Conclusion: The current FEM predicted ROM as measured by invitro study. Thus, it may be used for first prediction of the initial stability of a new device or for first analysis on the shape of new cspine implants. However, the limits of FEM should be kept in mind. Table 1 Results of in-vitro study and FEM In-vitro intact Flexion/Extension Bending Rotation

In-vitro In-vitro bicortical monocortical

FEM 1 FEM 2 FEM 3

9.8±2.7

3.2±3.8

1.2±1.0

7.3

2.2

2.2

8.1±2.9 10.3±4.0

2.6±2.7 3.6±3.2

1.4±1.0 2.3±1.2

5.2 8.2

2.4 3.0

2.4 3.0

122 VALUE OF THE BELL TEST AND THE HYPEREXTENSION TEST FOR DIAGNOSIS IN SCIATICA ASSOCIATED WITH DISC HERNIATION: COMPARISON WITH LASÉGUE’S AND CROSSED LASËGUE’S SIGN S. Poiraudeau, V. Foltz, F. Rannou, J.L. Drapé, J. Fermanian, M.M. Lefêvre-Colau, M.A. Mayoux-Benhamou, M. Revel Hôpital Cochin, Service de rééducation et de réadaptation de l’appareil locomoteur et des pathologies du rachis, Assistance Publique-Hopitaux de Paris, Université René Descartes, 27 Rue du Fbg St Jacques, 75014 Paris, France Study design: Prospective study analyzing intra- and interobserver reliability, sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values of four clinical tests. Objectives: To evaluate the reliability, sensitivity, specificity, PPV, and NPV for the diagnosis of sciatica associated with disc herniation of the bell test (BT) and the hyperextension test (HT). Summary of background data: There is no evidence that a particular clinical presentation can discriminate sciatica associated with disc herniation from sciatica of other mechanical origin. Methods: Patients with sciatica were included. According to MRI, CT scan, or myelography findings, patients were classified as sciatica associated with disc herniation (group A), or sciatica of other mechanical origin (group B). Four clinical maneuvers (bell sign (BS), hyperextension test (HE), LasËgue’s sign (LS), and crossed LasËgue’s sign (CL)) were tested by 3 investigators, and the intraand interobserver reliability were calculated using the k coefficient correlation or the intraclass correlation coefficient (ICC). Multiple regression analysis was performed to determine the best set of variables predicting sciatica caused by disc herniation, and the sensitivity, specificity, PPV, and NPV of the 4 maneuvers were calculated. Results: 78 patients (43 in group A, 35 in group B; 33 males) with a mean age of 50±16 years were included. Intra-observer reliabilities ranged from 0.76 to 0.96. Interobserver reliabilities ranged from 0.58 to 0.64 for BT, 0.35 to 0.50 for HE, 0.27 to 0.47 for LS, and 0.43 to 0.72 for CL. LS had the best sensitivity (0.77 to 0.83), CL the best specificity (0.74 to 0.89) while PPV and NPV were equivalent for the 4 maneuvers (0.55 to 0.75 for PPV and 0.45 to

0.59 for NPV). The best PPV was observed for the association of HE and CL (0.67 to 0.85). Multiple regression analysis did not allow to propose a set of variables predicting sciatica caused by disc herniation. Conclusion: This study suggests that clinical values of BS and HE are of interest, comparable with those of LS and CL. 123 NEUROLOGICAL DETERIORATION IN ADULT CASES OF SPLIT CORD MALFORMATIONS E. Put1, F. Weyns1, E. Beuls2 1Dept. of Neurosurgery, Z.O.L. Campus St.-Jan, Genk, Belgium; 2Dept. of Neurosurgery, University Hospital Maastricht, The Netherlands Objective: The purpose of this presentation is to analyse the anatomical features, responsible for the very rarely reported onset of symptoms in adult cases of split cord malformations (SCM) and to present some guidelines for treatment. Material and Methods: We studied 8 adult cases and reviewed 67 patients described in the literature. Results: Seven cases presented with a lumbar SCM and one case with a cervical SCM. Seven patients had a type II SCM, one had a type I SCM. In 2 patients complaints started after surgery for a congenital scoliosis. Six patients had pre-existing neuro-orthopaedic symptoms. Cutaneous lesions were found in 5 cases. Five patients presented with back/leg pain, 3 patients with a sensorimotor deficit, 4 patients with bladder/bowel deficit, one with a foot ulcer and one with a subcutaneous lipoma. No spur could be demonstrated on MRI in 3 cases. Five cases underwent surgery because of pain and/or progressive neurological deficit. Pain was improved in all cases, sensorimotor deficit was improved in 2 cases and stabilised in one. Bladder/bowel deficit improved in 3 cases and remained stable in one. An extensive literature review will be presented. Conclusion: A local injury theory in which even minute lesions can lead to a diminished vascular supply is postulated. Pain is the most prominent symptom in adults and can be totally relieved by surgery. Sensorimotor and bladder/bowel deficits can improve markedly after surgery. The split must always be explored and a septum is always found during surgery even if MRI was negative. Surgery is indicated in pain, progressive neurological deficit and before scoliosis surgery, but the role of prophylactic surgery remains unclear. 124 HISTOCHEMICAL EVALUATIONS OF MATRIX CHANGES FOLLOWING ANNULAR INJURY IN AN EXPERIMENTAL MODEL OF INTERVERTEBRAL DISC DEGENERATION A.S. Rai, J.M. Melrose, S. Smith, J.K. Rai, J. Kitson, S.Y. Hwa, P. Ghosh, T.K. Taylor Institute of Bone and Joint Research, Royal North Shore Hospital, St Leonards, Sydney, NSW 2065 Australia Systematic studies of cadavers have shown that, compared with ‘normal’ young lumbar intervertebral discs (IVD), discs in older age groups are subject to a range of pathological lesions. The ovine model of experimental disc degeneration allows changes in IVD composition/structure to be followed longitudinally through all stages of disc degeneration. The intention of this study is to describe the changes in the distribution pattern of type I,II and VI collagen and the matrix changes with the onset of degeneration in the ovine model of disc degeneration. A total of 32 pure bred merino wether sheep aged –4 years at the inception of the study

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were used in this investigation. The animals were divided into sham and lesion groups. The lesion sheep group received a controlled 4 mm deep surgical incision in the left anterolateral annulus adjacent to the inferior cartilaginous endplate of the superior vertebral of the L1L2 and L3L4 IVD. The sham operated control sheep received the same retroperitoneal surgical approach to the annulus but in this case it was not incised. Animals were sacrificed 3,6,12 and 26 months post operation and spinal segments were removed in-toto within one hour of death. All specimens were processed for histologic and immunohistochemical analysis. The outer margins of the annular rim lesion underwent re-organisation, but the inner lesion propagates through to the previously unaffected IAF and eventually destroys the NP organisation. We observed a distinct staining pattern for collagen types I, II and VI in the IVD of lesion and control IVDs. There was a distinct pericellular distribution of type VI collagen (similar to that seen in articular cartilage) in the lesion IVDs. The altered composition of the collagens and the matrix suggests that the disc cells change their cellular phenotype in response to the change in the biomechanics of the IVD. Comparisons of the morphologies of experimental annular lesions and those present in human cadavers indicate that the ovine annular lesion model reproduces IVD defects similar to those encountered in man. This model may prove to be useful in the systematic evaluation of therapeutic intervention or other treatment modalities (i.e. gene therapy), which may potentially prevent or reduce disc degeneration and improve repair of pathological IVD defects. 125 ANULUS FIBROSUS CELLS CULTURED IN A MECHNICALLY ACTIVE ENVIRONMENT: LOCAL CULTURE CONDITION ADAPTATIONS AND CELL PHENOTYPE F. Rannou, S. Poiraudeau, V. Foltz, M. Boiteux, M. Corvol, M. Revel Hôpital Cochin, Service de rééducation et de réadaptation de l’appareil locomoteur et des pathologies du rachis, Assistance Publique-Hopitaux de Paris, Université René Descartes, 27 Rue du Fbg St Jacques, 75014 Paris, France

not induce cell detachment from the substrate, did not modify aggregating properties of neosynthesized proteoglycans and AF cells continued to express collagen type II but not collagen type I mRNA. Conclusion: The Flexercell system appears to be appropriate to study, at the cellular level, the metabolic responses to CTS. 126 THE EFFECT OF FINANCIAL COMPENSATION INVOLVEMENT ON THE OUTCOME FOR CERVICAL RADICULAR PAIN C. Rasmussen, L. Rechter, I. Schmidt, V.K. Hansen, K. Therkelsen Dept. Rheumatology, Hjoerring Hospital, DK – 9800 Hjoerring, Denmark The aim of this study was to examine the influence that financial compensation involvement has on the results of physiotherapeutic McKenzie treatment on cervical radicular pain. The patients were referred in a two year period to the Spine Clinic after at least five weeks of neck pain irradiating to the arm. This study was based on prospectively collected data for quality assurance purpose with baseline classification. Follow-up included a validated, questionnaire to measure the outcomes: Neck and arm pain, disability, use of analgesics and the perceived effect of the treatment registred by the patient. At baseline, the 15 patients with and the 45 patients without compensation issues were identical in regard to their neurological and clinical signs. Number of patients with: Paresis: 28; sensory dysaestesia 36 or reflex disturbances: 28. Median age was 46 years (19–64) with 32 being females. Three patients were operated a. m. Cloward. Follow-up (58 of 60 patients) showed that one year later there was no improvement in the group of 15 patients with compensation involvement, in contrast to the group of 43 patients without compensation involvement who showed highly significant improvement. The results applied to all 5 outcome measures. In conclusion, compensation involvement seems to act as a negative factor on treatment results for patients with cervical radicular pain. 127

Objectives: To assess the phenotype of intervertebral disc cells from the Anulus Fibrosus (AF) region cultured on flexible substrate before and after application of cyclic tensile stretch (CTS) and to control culture conditions during application of CTS. Summary of background data: Intervertebral disc cells can be cultured in vitro, and several culturing systems in a mechanically active environment have been developed to study the relationship between mechanical stimulations and biochemical events. Methods: After enzymatic digestion of rabbit intervertebral disc, AF cells were cultured at high density on flexible substrate. CTS was applied using a pressure-operated instrument inducing the deformation of flexible-bottomed culture plates (Flexercell strain unit FX3000). Local culture conditions (culture medium volume and temperature) were measured. Proteoglycan aggregability was studied by the elution profile on sepharose 2B columns after 35Ssulfate incorporation. Cell content of collagen type II and type I mRNA was determined by Northern blotting. Cell adhesion was evaluated before and after stretch. Results: Cells were confluent after 6 days. CTS application was delivered at 20% and 5% elongation at a frequency of 1 Hz during 30mn to 24 h. A significant decrease in culture medium volume and temperature was observed (66% and 2.2°C at 20% elongation and 24 h application of CTS). These phenomenons were inhibited by adding culture medium around culture wells and by a culture medium temperature control system. Like AF cells cultured in plastic wells, AF cells cultured on flexible substrate expressed collagen type II but collagen type I mRNA was not detected. In both culture conditions, neosynthesized protéoglycans had the same aggregating properties. CTS at 20% elongation during 12 hours did

PRESENCE OF PARESIS AND OUTCOME IN PATIENTS WITH CERVICAL NERVEROOT COMPRESSION C. Rasmussen, V.K. Hansen, I. Schmidt, L. Rechter, K. Therkelsen Spine Clinic, Dept. Rheumatology, Aalborg Hospital, DK-9000 Aalborg, Denmark Initial treatment of choice for cervical nerveroot compression is physiotherapy. The presence of paresis is often regarded as an unpleasant complication pointing at surgery. The aim of the study was to examine the effect of paresis on the outcome after clinical cervical nerveroot compression treated with the McKenzie physiotherapeutic method. Patients were referred after a minimum of five weeks of neck pain irradiating to the arm. In the Spine Clinic the patients were examined and prospectively classified by a rheumatologist and a McKenzie physiotherapist. Included were 64 (32F) patients, median age 45 (19–64) years. 35 patients had paresis: Paresis only (3), paresis combined with either sensibility or reflex disturbances (19) or all 3 signs (13). The 29 patients without paresis had sensibility or reflex disturbances and 6 had no definite neurological deficit. Three patients were operated. Follow-up one year later (57 of 64 patients) was done by a validated questionnaire regarding neck pain, arm pain, disability, intake of analgesics and the patients’ perceived effect of the treatment. Standard nonparametric statistics was used. Results were equal in both groups with a nonsignificant trend to more arm pain in the paresisgroup. In conclusion, the presence or absence of paresis has no effect on the outcome for clinical cervical nerveroot compression treated with the McKenzie method.

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FACTORS AFFECTING THE LOADS ON INTERNAL SPINAL FIXATORS A. Rohlmann, G. Bergmann, F. Graichen Orthopaedic Hospital of the Free University of Berlin, Oskar-Helene-Heim, Clayallee 229, 14195 Berlin, Germany

MORPHOLOGY OF LUMBAR DISCS UNDER MRI IN THE SITTING, STANDING, AND FORWARD FLEXION POSITIONS: DOES DISC DYNAMICS CHANGE FROM NORMAL TO DEGENERATED CONDITIONS. A PROSPECTIVE STUDY J.F. Roy, C. Lindsay, J.M. Moutquin, Montminy, M. Lamontagne Hopital St. Francois D’Assise, 10 Rue de L’Espinay, Québec, PQ,Canada, G1L 3L5

The aim of this experimental study was to show the factors decisive for the fixator loads. Bisegmental telemeterized internal spinal fixation devices were implanted in ten patients and their loads were measured for various activities. Most important are the axial force and the bending moment in the longitudinal rod. It could be shown that axial fixator force mainly depends on the level bridged by the fixators. Fixators are mounted on the concave side in the lumbar spine and on the convex side in the thoracic spine. In an upright body position, the natural curvature is slightly increased due to gravitational force. Therefore, when moving from a lying to an upright body position, axial fixator loads are increased by concave (lumbar spine) and decreased by convex sided implant fixation (thoracic spine). Before anterior interbody fusion, the bending moments in the implants were low in the cases which evidenced a degenerative instability and high in the cases with a fractured vertebral body. After anterior interbody fusion fixator loads were high when the bridged region was distracted and low when it was compressed. Implant loads were higher in an upright than in a lying body position. They were not higher for sitting than for standing. The load changes during flexion of the upper body were only small. Carrying a load had only a minor effect on implant loads. This indicates that other structures take over the additional load. A brace had only a negligible influence on the implant loads.

129 LOADS ON INTERNAL SPINAL FIXATORS ARE ONLY SLIGHTLY AFFECTED BY CARRYING A WEIGHT A. Rohlmann, G. Bergmann, F. Graichen Orthopaedic Hospital of the Free University of Berlin, Oskar-Helene-Heim, Clayallee 229, 14195 Berlin, Germany After stabilising a spine with an implant, patients want to know whether carrying weights endangers their spine and the implant. The aim of this experimental study was to determine the influence of weight carrying on loads in internal spinal fixators. Bisegmental instrumented internal fixators were implanted in ten patients. The patients carried 5 kg and 10 kg dumbbells in both hands. They also raised their outstretched arms in anteversion while holding different weights in both hands. Compared to normal standing carrying a weight caused only a slight increase of the fixator loads in all patients. The maximum flexion bending moment in the fixators was then lower than during walking. Carrying a weight even decreased the axial compression force in the fixators of the patients with the T11 or T12 vertebra bridged. Raising the outstretched arms from a hanging to a horizontal forward position causes an additional flexion bending moment in the trunk. Only a very small part of this additional bending moment is taken over by the fixators. After stabilising a spine with an implant, spinal load is shared in the bridged region by the spine and the implant. The bending moment in the implants depends strongly on the stiffness of the bridged region and thus on the surgical procedure. Implant loads mostly increased only slightly when carrying additional loads. This means that other structures had taken over the load.

Disc area, height, and canal diameter at L4-L5 or L5-S1 levels were measured in 50 asymptomatic Individuals. All had an absent history of back or leg pain. Each had a normal lumbar physical examination. Of these, 25 had degenerated lumbar discs and the 25 others had normal discs on MRI (1.5 tesla). MRI examinations (1.5 tesla) included the following positions; supine, sitting, kneeling, and in forward 30 degree flexion in the sitting and kneeling positions. A weight of 40 pounds was added in the kneeling and sitting positions. The variations noted in asymptomatic spines will serve as an atlas for the following study with symptomatic spines. 131 IMPROVEMENT OF THE BONE-SCREW INTERFACE WITH HYDROXYAPATITE COATING. AN EXPERIMENTAL STUDY OF LOADED SPINAL INSTRUMENTATION B. Sandén1, C. Johansson2, C. Olerud1, S. Larsson1 1Dept of Orthopaedics, Uppsala University Hospital; 2Dept of Biomaterials and Handicap Research, Gothenburg University, Sweden Introduction: Loosening of the screws is a problem in instrumentation with pedicle screws. Coating of loaded pedicle screws with plasma-sprayed hydroxyle apatite (HA) has been used in an experimental study where a significant increase of pull-out resistance could be shown. The aim with the present study was to examine the effects of HA coating of pedicle screws on the bone-screw interface. Methods: Nine sheep were operated on with destabilising laminectomies at two levels, L2-L3 and L4-L5. Two instrumentations with four pedicle screws in each were used (PF MiniSystem, Nordopedic, Uppsala, Sweden). Standard screws (stainless steel), or the same type of screws coated with plasma-sprayed HA were used in either the upper or the lower instrumentation in a randomised fashion. Three sheep were killed at 6 weeks and four sheep at 12 weeks. Two sheep were euthanized early due to complications. Four screws from each animal were examined, giving 14 HA coated screws and 14 standard screws. After preparation of the specimens light microscopy was performed, and also a histomorphometric evaluation using a Leitz Microvid unit connected to a PC. Results: The bone-to-implant contact was in the 6 week group 69% in the HA group and 18% in the standard group (p 0.028) and in the 12 week group 64% in the HA group and 9% in the standard group (p 0.012). Conclusion: Hydroxyapatite coating of pedicle screws greatly improves the bone-to-implant contact. This corresponds to the earlier demonstrated improvement of pull-out resistance with HA coating.

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132 CLINICAL RELEVANCE OF SPECIFIC PARAMETERS ISOLATED WITHIN THE GREEK TRANSLATION OF THE OSWESTRY AND ROLAND-MORRIS FUNCTIONAL DISABILITY SCALES G. Sapkas1, P. Boscainos1, E. Stilianesi1, C. Prouskas2 11st Orthopaedic Department of Athens University, Athens, Greece; 2Psychometrician, Age Concern Institute of Gerontology, Kings College London, University of London, London, UK Disability scaling scores and pain drawings have been used for the evaluation of patients experiencing low back pain. Psychometric factors related to symptoms and expressions of disability in each patient exist within these scaling systems. The isolation of such factors may lead to a further understanding of the assessment performed by such scaling systems. Between 1985 and 1999, 697 patients with low back pain have been examined at the out-patient clinic of the 1st Orthopaedic Department of Athens University and have been asked to complete a questionnaire, which included the above mentioned scales and also draw a pattern of the distribution and characteristics of their pain. Two physicians of the department, that have had no contact with the patients in the study, scored their responses and results have been assessed statistically. There are 4 parameters (Eigen values >.8) emerging from the factor analysis of the Oswestry scale and 6 (Eigen values >.95) emerging from the factor analysis of Roland-Morris functional disability scale. Both scales correlate well with each other at the.01 level. There is a statistically significant difference between organic and non-organic pain concerning the Roland-Morris total score (p=0.002). The difference between Oswestry total score and organic and non-organic pain was not statistically significant. Factor analysis of the Greek translation of the Oswestry and Roland-Morris functional disability scales reveals definite parameters that can be used to assess severity of symptoms and disability in patients with low back pain. It would be interesting to compare these results with relevant parameters established in studies in other countries leading to isolation of functional disability universal indices.

133 QUANTIFYING THE STRESS INDUCED BY DISTRESS IN PATIENT WITH LUMBAR DISC HERNIATION AS RELATED TO MEASUREMENTS OF NATURAL KILLER CELL ACTIVITY; CHROMIUM RELEASE ASSAY VERSUS MULTIPARAMETER FLOW CYTOMETRIC ASSAY N. Sato, K. Sato, S. Kikuchi Department of Orthopedic Surgery, Fukushima Medical University, School of Medicine, 1 Hikarigaoka, Fukushima City Fukushima, 960–1295, Japan Objectives: The purpose of this study was (1) to quantify the stress in the patient with lumbar disc herniation by measuring Natural Killer (NK) cell activity, and (2) to compare the standard chromium release assay (CRA) with a new multiparameter flow cytometric assay (FCA). Summary of the background data: Stressful events may have adverse effects on health. Distress in the patient with lumbar disc herniation may also be a stressful event. The activity of NK cells has previously been found to be impaired following examination, bereavement, or other stressful life events. However, the relationship between stress and pain in the patient with lumbar disc herniation has not been evaluated. The standard assay for NK cell activity has been the chromium release assay. However, this assay requires the use of radioactive chromium. On the other hand, FCA is a nonradioactive method, and analyses the activated NK-lymphocyte subsets (CD45+, CD56+, CD69+).

Methods: Peripheral blood lymphocytes were obtained from twenty patients with lumbar disc herniation (mean age, 30.8 years) and twenty healthy individuals (mean age, 38.9 years). Both CRA and FCA were performed in each patient. Results: 1) The mean NK cell activity of the healthy volunteers was 12.6% and 11.0% for the CRA and FCA, respectively. The correlation (r=0.86) in NK cell activity between the two methods was high. In addition, there was no statistically significant difference between the two methods (p<0.05). 2) The mean NK cell activity of the patients (8.0%) by CRA was statistically significant lower (p<0.05) than that of 20 healthy adult volunteers who were assayed by CRA (mean NK cell activity, 12.6%). Conclusion: NK cell activity in the patients with lumbar disc herniation was statistically significant lower than that of healthy subjects. Thus, this result may indicate that stress is present in patients with lumbar disc herniation. For measuring NK cell activity, FCA gave results similar to those of the CRA and was a viable alternative to the CRA. 134 BIOMECHANICAL CHARACTERIZATION OF THE ACROFLEX LUMBAR DISC H. Serhan, R. Ross, G. Lowery, R. Fraser DePuy AcroMed, 325 Paramount Drive, Raynham, MA 02767, USA Background: The AcroFlex disc consists of proprietary polyolefin rubber core bonded between two titanium endplates. It has been developed for the treatment of symptomatic disc degeneration with the aim of providing segmental stability and motion following wide disc space clearance. It was designed to have similar properties to a normal adult human intervertebral disc when working in conjunction with the retained anulo-vertebral tissues and the supporting musculoligamentous system. Materials and Methods: Over 120 discs were used to biomechanically characterize the AcroFlex Device. Range of motion tests were designed and performed to measure the axial compression, torsional, and shear stiffness of the AcroFlex disc and to compare this with the known values for the human lumbar disc. Pullout test was performed to evaluate the immediate and short-term stability of the inserted device by assessing the mechanical resistance to pullout or expulsion. To assess the ability of the implant to withstand average daily living loads throughout its predicted life, compression and compressive shear fatigue testing were performed. Results and conclusion: In the range of motion testing the device was found to replicate many of the physiologic characteristics of the in-vivo FSU. The quasi-static compression, compressive shear and torsion testing showed the device to have higher strength values than the highest in-vivo measured loads of 3,400 N. Fatigue testing showed the smallest device endurance limit of 3,500 N at ten million cycles. The results demonstrate that the failure modes of the device contain sufficient safety margins to support the use of the device in a prospective clinical study. 135 INSTRUMENTED ANTERIOR DEBRIDEMENT AND ARTHRODESIS OF THE SPINE TUBERCULOSIS E. Sesli, O. Halit, C. Erhan, O. Nadir, T. Levent Ege University Medical School Department of Orthopaedy and Traumatology 35100 Bornova Izmir, Turkey Fifty-five patients who had tuberculosis of the spine that was treated by debridement and instrumented anterior fusion were reviwed for four years or more postoperavively. Our indications for operation were neurological impairment, mechanical instability

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and/or existing huge abscess. Eighty-seven per cent of neurologic impaired patients recovered normal neurologic function after anterior decompression and drainage of the abscess. Follow up, there were no findings about reinfection in these patients. The results show that anterior debridement and instrumented fusion with chemotherapy at least nine months were succesfull the treatment of the spinal tuberculosis. 136 FACTORS INVOLVED IN POSTSURGICAL SPINAL INSTABILITY N. Specchia, F. Greco, R. Politano Dept. Orthop. University of Ancona – P.za Cappelli 1, 60121 Ancona, Italy Introduction: Many biological and mechanical factors are involved in postsurgical spinal instability. The present report deals in evaluating two main aspects: the mechanical behaviour of the construct with respect to the geometry of the instrumentation, and the interaction between the healing process of the fusion mass and the instrumentation. Methods: Our series consists of 27 patients (out of 429 consecutive spinal surgical procedures) suffering from postsurgical spinal instability, who underwent revision surgery, from 1992 up to 1997. Lumbar disc herniation, spinal stenosis, spondilolysthesis, spondylitis, tumors, and fractures were the lesions involved. Spinal instability was due to implant failure in 18 patients, and to postlaminectomy deformity (kyphosis) in 9 patients. Patients underwent X-ray, CT, MRI, and bone-scan examination. Bone bioptic specimens were collected from the fusion mass in each patient during the surgical procedure. Each specimen underwent histological and histomorphometrical analysis. Results: Implant failure was always observed in unfused spine or in the presence of pseudoarthrosis of the fusion mass. Results clearly show that instrumentation markedly affects the healing process of the fusion mass. Indeed, the fused area evidences a remarkable structural difference between simple fusion and instrumented arthrodesis. In the former, the area of arthrodesis is wider, homogeneously distributed and similar to a cortical wall; in the latter, the grafted area is smaller, not homogeneous and osteoporotic. Discussion and conclusion: Paradoxically, although the theoretical function of fixation is to ensure the early stabilisation of the bone graft and to allow fusion, in practice, the osteosynthesis becomes the major hindrance for graft remodelling.

137 OSTEOBLAST-LIKE ACTIVITY OF HUMAN LIGAMENTUM FLAVUM CELLS IN LUMBAR STENOSIS N. Specchia, A. Pagnotta, A. Toesca, A. Gigante Dept. Orthop. University of Ancona – P.za Cappelli 1, 60121 Ancona, Italy Introduction: The hypertrophied ligamentum flavum play a major role in the pathogenesis of the lumbar stenosis with 3 different mechanisms: proliferation of type II collagen, ossification, and calcium crystal deposition. The aim of this study was to investigate the pathogenesis of the degenerative changes of the ligamentum flavum occurring in lumbar spine stenosis. Methods: Samples of ligamentum flavum were collected from 8 patients undergoing surgery for lumbar stenosis and from 4 control patients with lumbar fractures. Histology and immunohistochemistry of the tissue has been performed. Cell cultures were obtained from each patient and histochemically, immuno-histochemically, and biochemically characterized.

Results: Stenotic ligamentum flavum cells expressed high levels of alkaline phosphatase activity and produced a matrix rich in type I, type III and type X collagen, fibronectin, osteonectin, and osteocalcin. Stimulation with PTH increased intracellular cAMP concentration. These findings indicate that there was significant evidence of osteoblast-like activity in these cells. Staining for type II and type X collagen, and S-100 protein reflected the proliferation of hypertrophic chondrocyte-like cells, confirmed with the co-localization of alkaline phosphatase and collagen type II. Cultures from control patients showed nor hypertrophic chondrocytic nor osteoblastic features. Discussion and conclusion: Our data demonstrated the presence of hypertrophic chondrocytes with an osteoblast-like activity in human stenotic ligamentum flavum. The osteoblast-like activity could underlie the phenotypic changes of the matrix, and it could have a role in the pathophysiology of the ligamentum flavum degeneration in lumbar spine stenosis. 138 NONOPERATIVE TREATMENT OF ACUTE SPONDYLOLYSIS IN COMPETITITVE ATHLETES J. Sys, J. Michielsen, J. Verstreken, P. Bracke Dept. Of Orthopaedics, University Hospital of Antwerp, Wilrijkstraat 10, 2650 Edegem, Antwerp, Belgium The purpose of this prospective study was to evaluate the healing capacity of fatigue fractures of the pars interarticularis in young elite athletes. Between 1991 and 1999, a fatigue fracture of the pars interarticularis was diagnosed in 34 highly competitive athletes. All subjects were initially treated with bracing. Twenty-nine of the conservatively treated athletes were reviewed. Five athletes were lost for follow-up and one athlete was treated operatively. The study was limited to athletes with “subtle” fractures, which means that they had normal X-rays and positive SPECT-bonescans. All lesions were classified as either unilateral, bilateral, or “pseudo-bilateral” according to their scintigraphic appearance. When tracer uptake was present on both sides of one vertebra and when the uptake was clearly asymmetrical, the lesion was called “pseudo-bilateral”. Athletes with this finding were classified separately because a distinct healing pattern became apparent throughout the course of this study. In pseudo-bilateral lesions only one fracture was considered recent. Scintigraphic studies were performed at 2- and 4-months intervals and CT scan was used to evaluate healing of the fracture. Bracing was performed according to the persistence of pain and the scintigraphic evolution. We looked at both healing of the fracture and subjective outcome in the 3 groups. The difference in healing potential between the 3 goups was statistically significant (P<0.05). There were no differences in outcome nor sports resumption between the 3 groups. Conclusion: Although the number of patients is too small for a valid statistical analysis, our data suggest an association between early brace treatment and osseous healing. Chances for bony healing diminish when the fracture is bilateral – and even more if the fracture is pseudo-bilateral -, probably because one of the fractures occurred earlier and therefore has less healing potential. We consider (pseudo-)bilateral pars fractures as a next step towards chronic spondylolysis. 139 A HISTOLOGIC STUDY ON CAUDA EQUINA ADHESIONS INDUCED BY MULTIPLE LAMINECTOMIES N. Takahashi, S. Konno, S. Kikuchi Dept of Orthopaedics, Fukushima Medical University 1, Hikarigaoka Fukushima City, Japan

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It is well known that laminectomy induces adhesion of cauda equina. However, the relation between the range of laminectomy and histologic changes of the cauda equina induced by laminectomy is not clear. Materials and Methods: Sixty-five Sprague-Dawley rats were used. They were divided into four groups according to the range of laminectomy. 1. No-laminectomy group(sham group) n= 5 2. Single laminectomy group(L5) n=20 3. Double laminectomies group(L5,L6) n=20 4. Tripple laminectomies group(L4,L5,L6) n=20 At 24 hours, 1week, 3weeks, and 6weeks after the laminectomy, the rats in each group were sacrificed and specimens from L4 to L6 were obtained. The histologic changes were assessed using the classification of Yamagami. (grade1: normal finding, most nerve rootlets distributed separately in the subarachinoid space; grade2: more than half of the nerve rootlets grouped together; grade3: all nerve rootlets grouped or adhere to form a lump; grade4: the lumped adhesion of all nerve rootlets adheres to the dura mater.) Results: The sham group was assessed as grade1 at each follow-up time. The single laminectomy group was defined as grade3~4 at 24hours after laminectomy. However, the adhesion of cauda equina had recovered 1week after the laminectomy. The double laminectomy group presented a grade3~4 at 24 hours after laminectomy. However, the adhesion of cauda equina had recovered 3weeks after laminectomy. The tripple laminectomy group was assessed as grade3~4 at 24hours and 1week after laminectomy. However, adhesive change recovered to grade2~3 at 3weeks after laminectomy, grade1~3 at 6weeks after laminectomy. Conclusion: The range of laminectomy was closely related to the recovery of cauda equina adhesion induced by laminectomy. 140 COMPOSITE FLOW MOULDING: A TECHNIQUE TO PROCESS A NEW HIGH-STRENGTH, RADIOLUCENT, NONMAGNETIC COMPOSITE MATERIAL FOR SPINAL IMPLANTS SUCH AS SCREWS AND TRANSLAMINAR PINS R. Tognini, F. Magerl ETH-Zürich BWB, c/o Kapellweg 26, 9443 Widnau, Switzerland The Composite Flow Moulding (CFM) is a new production technique for thermoplastic composite materials to address the high demands of implants in general, and of spinal implants in particular. The new production process allows the use of highly reinforced materials (i.e. 61 vol. % carbon fibre fraction with PEEK), with the option of tailor made mechanical properties like elastic modulus and the controlled incorporation of non-magnetic, metallic X-ray markers, which do not interfere with CT or NMR applications. As CMF is a net-shape processing technique, screw threads and other protruding or intruding parts of an implant will be of exceptional strength thanks to the moulding process, with no fibres at the implant surface. The processing of the high fibre content also results in a superior fatigue resistance, as the otherwise unfavourable influence of notches is minimised by the endless fibres embedded in the thermoplastic material. Conventional production techniques like milling or water cutting would lead to delamination, shear of threads, dissemination of fibres etc. In a simulated translaminar facet screw fixation (TFSF) the new Composite Translaminar Pins have been shown to be superior to the standard 4.5 Titanium screws (fatigue strength plus 50%) and have also delivered very good results in static 3-point bending tests (plus 30%). These encouraging results with composite materials based on thermoplastic matrices allow for a new range of net-shape spinal implants with the advantages of high strength, proven biocompatibility (newly launched medical grade Optima PEEK, Victrex plc), and controlled radiological or NMR behaviour.

141 DEVELOPMENT ANF VALIDATION OF AN ISTANBUL LOW BACK PAIN DISABILITY INDEX (ILBPDI) M. Tuncay Duruoz1, E. Ozcan2, A. Ketenci2, A. Karan2 1Physical Medicine & Rehabilitation Department, Celal Bayar University, Tip Fakultesi, Fiziksel Tip ve Rehabilitasyon A.B.D., Manisa, Turkey; 2Physical Medicine & Rehabilitation Department, Istanbul University Istanbul Medical Faculty, Istanbul, Turkey Objective: To develop and to assess the validity of a functional disability scale for low back pain (LBP) in a Turkish population. Methods: In and outpatients with LBP for at least 3 months were selected randomly. Patients with inflammatory LBP were excluded. Interrater reliability and internal consistency (Cronbach’s ·) were examined. Face, content validities were investigated. Convergent validity was assessed by correlating ILBPDI with other functional LBP scales (Quebec Back Pain Disability Scale, QBPDS; Oswestry Disability Index, ODI; Waddell’s Functional Index, WFI). Divergent validity was assessed by correlating ILBPDI with variables known to have a moderate or no relation with functional disability. Factor Analysis followed by varimax rotation was performed. Results: 112 patients (71 female) with mean age 39.93 (±12.92) were recruited. The provisional scale had 66 questions. The elimination process left 18 daily activity questions. The interrater reliability was 0.79 and Cronbach’s alpha was 0.90. The ILBPDI had good convergence with the QBPDS (r: 0.82), the ODI (r: 0.76), WFI (r: 0.68). The ILBPDI had either fair or non significant relation (divergence) with VAS-lumbar, VAS-radicular, Beck Depression Inventory, morning stiffness, night pain, finger-floor distance, radicular pain’s duration, modified Schöber’s index and other non functional parameters. The ILBPDI had 2 main factors by factor analysis. First factor contained 11 questions on activities implicating forward bending and the second factor contained 7 questions on standing activities. Conclusion: We have developed a reliable, accurate and practical functional disability scale for LBP which has been validated in a Turkish population. 142 CROSS CULTURAL VALIDATION OF THE REVISED OSWESTRY PAIN QUESTIONNAIRE (ROPQ) IN A TURKISH POPULATION M. Tuncay Duruoz1, E. Ozcan2, A. Ketenci2, A. Karan2, M.Z. Kiralp3 1Physical Medicine & Rehabilitation (PM&R) Department, Celal Bayar University, Tip Fakultesi, Fiziksel Tip ve Rehabilitasyon A.B.D, Manisa, Turkey; PM&R Departments; 2Istanbul University Istanbul Medical Faculty; 3GATA Haydarpasa Training Hospital, Istanbul, Turkey Objective: To cross-culturally adapt and to validate the Turkish version of the Revised Oswestry Pain Questionnaire (ROPQ) to suit the needs of Turkish speaking patients. Methods: Out and inpatients with low back pain (LBP) for at least 3 months were selected randomly. The inflammatory LBP was in the exclusion criteria The ROPQ was modified in the context of Turkish culture and translated into Turkish with “back translation method”. Internal consistency (Cronbach) and interrater reliability of the scale were examined. Convergent validity was assessed by correlating ROPQ (Pearson’s Correlation Coefficient: r) with other functional LBP scales (Istanbul Low Back Pain Disability Index: ILBPDI; Quebec Back Pain Disability Scale: QBPDS; Waddell’s Functional Index: WFI and Visual Analog Scale of Handicap: VASHd). Divergent validity was assessed by correlating ROPQ with variables known to have a moderate or no relation with functional disability.

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Results: 132 patients (85 female) with mean age 41.70 (±14.01) were recruited. Cronbach- was 0.80 and interrater reliability (ICC) was 0.74. High convergence was found between ROPQ and other functional LBP scales (ILBPDI, r: 0.78, p<0.00001; QBPDS, r: 0.79, p<0.00001; WFI, r: 0.70, p<0.00001; VASHd, 0.53, p< 0.00001). The ROPQ had no significant or fair relation (divergence) with age, morning stiffness, night pain, finger-floor distance, radicular pain’s duration, VAS-lumbar and Schöber’s index. There was moderate relation with VAS-radicular (r: 0.46), and the Beck Depression Inventory (r: 0.40). Conclusion: The Turkish version of the ROPQ is reliable and valid instrument for studies measuring functional disability and functional handicap due to the LBP. 143 CAUDA EQUINA SYNDROME FOLLOWING OXYGENOZONE THERAPY. A REPORT OF EIGHT CASES A. Valassina, S. Lupparelli, S. Cecconi, A. Beccarini, L. Lucania Centro Ortopedico Umbro – via Solatia 3–06121 Perugia, Italy Introduction: Oxygen-ozone therapy is currently employed for treating sciatica due to disc herniation. However, the perusal of the Literature does not evidence, to our best knowledge, any experimental study analysing the effects of ozone on neural structures. In this paper we review eight cases of patients we operated on for cauda equina syndrome following both intra-discal and paravertebral ozone infiltration for lumbar disc herniation. Clinical cases:Eight patients who had received intradiscal or paravertebral ozone infiltration were admitted to our department for a cauda equina syndrome. The MR examination revealed a massive disc prolapse at L5-S1 in four patients and at L4-L5 in the remaining four. All patients underwent a standard discectomy through a bilateral laminotomy access. In all cases a severe delamination of the dural sac was found along with a detachment of the disc outermost annular fibres from the vertebral body. Discussion: The intra-operative findings cannot prove a causal relationship between the oxygen-ozone therapy and the onset of the cauda equina syndrome. Yet the severe delamination of the dural sac and the profound alterations of the annular insertions are rare findings in lumbar disc herniation. In the lack of experimental studies, we hypothesise that ozone may affect the structural integrity of both the neural sac and the annulus fibrosus, leading to a cumulative effect of massive disc prolapse and direct neural damage, which may end up with a cauda equina syndrome. 144 COMPRESSION STRENGTH ESTIMATES OF VERTEBRAE FROM BONE MINERAL CONTENT CAN BE IMPROVED BY NON-LINEAR REGRESSION J.H. van Dieën1, R. Huiskes2 1Institute for Fundamental and Clinical Human Movement Sciences, Faculty of Human Movement Sciences, Free University Amsterdam; 2Orthopaedics Research Laboratory, University of Nijmegen, The Netherlands Several studies provide regression equations on the relation between bone mineral content and compression strength of vertebrae. These equations form the basis for statistical models for fracture risk in epidemiological studies on osteoporosis. However, the regression equations from the literature, yield widely diverging predictions, especially for specimens with a low bone mineral content. Most of the equations reported are linear, while several authors have suggested that a curvi-linear fit might provide better strength estimates. In the present study, the data provided in three papers were therefore reanalysed using both linear and non-linear models

(including an intercept) to see which would provide more reliable estimates of compression strength. Whereas the differences between all of the linear regression equations were significant, fitting quadratic models yielded non-significant differences between the regression coefficients obtained from two out of the three studies. The data from the remaining study yielded a similar second order coefficient, but significantly different first order coefficient or intercept. This disparity may be explained by a higher force rate during the experiments and the fact that only in the latter study complete motion segments were tested. The distributions of the residuals of the quadratic models were much more favourable then of the linear models. The results from this study suggest that vertebral strength can be better estimated from bone mineral content measurements when a quadratic model is used. Prediction models for fracture risk associated with osteoporosis need to account for this non-linearity. 145 PATTERNS OF COUPLED MOTION IN THE CERVICAL SPINE IN RHEUMATOID ARTHRITIS PATIENTS (RA) P. Van Roy, L. Verbruggen, O. Maes, G. Cuppens, J.P. Baeyens, R. Lanssiers, J.P. Clarijs Vrije Universiteit Brussel, Department of Experimental Anatomy and Department of Rheumatology, Laarbeeklaan 103, 1090 Brussels, Belgium Using an electromagnetic tracking device (Flock of Birds), patterns of coupled motion in the cervical spine and the cervicothoracic transition zone were recorded in 29 RA-patients and 30 control subjects. The source was positioned in front of the cervical spine; sensors were connected to the manubrium sterni and forehead. After warming-up and instruction, data were recorded during three subsequent motions of left and right axial rotation of the cervical spine and three subsequent left and right lateral bendings. Summary of the results in the experimental group: Primary motion:

axial rotation

Coupled lateral bending:

ipsilateral ipsilateral + heterolateral ipsilateral + none ipsilateral + heterolateral + none heterolateral + none heterolateral

Primary motion:

lateral bending

Coupled axial rotation:

ipsilateral ipsilateral + heterolateral ipsilateral + none ipsilateral + heterolateral + none

16 4 3 3 2 1

25 2 1 1

Simultaneous display of Euler angles demonstrated the time characteristics of the coupled motion. Although most subjects of the control group showed ipsilateral coupling of axial rotation and lateral bending, amplitude and timing of coupled motion revealed left-right differences and individual characteristics. Variable flexion and extension components were seen in both groups. In conclusion the experimental group demonstrated: – More irregularity and inconsistency of the individual graphs. – An important number of aberrant motion patterns. In 14 RA-patients, axial rotation was accompanied by heterolateral lateral bending components or lack of lateral bending. Lateral bending was accompanied mostly by ipsilateral axial rotation, which approximated or exceeded the primary motion components in 14 out of 29 patients.

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146 TREATMENT OF SPINE TUMORS WITH CT-BASED COMPUTER NAVIGATION D. Vandevelde, J. Somville, J. Michielsen, J. Verstreken Department of Orthopaedic Surgery, University Hospital Antwerp, Belgium Spine tumors are sometimes a challenge for the surgeon. Computer guided surgery has already shown benefits in spine surgery and can help the spine surgeon to navigate in the bone and to perform a precise biopsy or treatment of the tumor. A lot of the tumors can not be seen on classic intra-operative fluoroscopic image and are therefore difficult to localize. The Medivision computer system was been used in more than 10 patients during the treatment of their tumor. For the pre-op planning and execution the Surgigate spine software and instruments were used. Advanced pre-operative planning on CT images with axial, sagittal and coronal reconstructions can provide the surgeon with essential information. Registration with minimal 3 paired points and a surface matching gave always very accurate results. Intra-operatively image guided surgery was used to localize the bone tumor and to navigate in the bone in order to remove the tumor or to determine the safe margins for resection. The indications were tumors in the cervical, dorsal and lumbar spine and in the sacrum. Localization of tumors like chondroblastoma and osteoid osteoma in the dorsal structures of the spine were treated. Computer navigation was also used for tumors in the sacrum like non-Hodgkin lymfoma and chordoma. Also an hemangioma was treated using transpedicular bone grafting in the dorsal spine. We had no complications related to the use of computer navigation. Computer assisted surgery is a very helpful tool for the spine surgeon in the different steps during the treatment of specific spine tumors. 147 C2-C3 TRAUMATIC SPONDYLOLISTHESIS OF THE AXIS; A COMPARISON BETWEEN THE TYPICAL AND ATYPICAL FORMS G.J. Velan, B.L. Currier, M.J. Yaszemsk Dep.of Orthopedic Surgery, Mayo Clinic and Mayo Foundation, Rochester, Minnesota, USA Introduction: This is a retrospective review of the clinical and radiographic features of patients, with traumatic spondylolisthesis of the axis, treated at our institution. The clinical and radiographic features of the typical type, where the fracture line is through the pedicles of the axis, were compared to those of the atypical type with the fracture through the body of the axis. Methods and patients: The charts and imaging studies of 534 patients treated at our institution for a cervical spine fracture, between 01/01/89 and 12/31/98, were searched for patients with a fracture through the pedicles, the posterior part of the vertebral body or the lateral mass of the axis. Only patients with plain films and CT scans, taken at time of injury, were included. Patient’s charts were studied for circumstances of injury, associated injuries, spinal cord injury, treatment method, and final clinical and radiographic outcome. Fractures were classified based on Levine and Edwards system for traumatic C2-C3 spondylolisthesis and subclassified based on the direction of the fracture line into coronal, oblique, and isolated lateral mass fractures. Comparisons of categorical variables were made with chi-square tests and Fisher’s exact tests (when expected counts were low). Continuous variables (e.g. age) were evaluated using rank sum tests. All statistical tests were two-sided, with the threshold of significance set at alpha= 0.05. Results: Of 534 patients with cervical spine fractures, 37 patients met the inclusion criteria, 25 patients had a fracture through the

body or the lateral mass of the axis (atypical group) and 12 had a fracture through the pedicles of the axis (typical group). Average age in the typical group was 31.2 years (Median 23, Range 12–67), and 47.0 years (Median 45, Range 18–94) in the atypical group, this difference was statistically significant (p=0.025). Gender distribution, circumstances of injury, and seatbelt use, were not significantly different between the two groups. 88% (22/25) of the patients in the atypical group and 58.4% (7/12) had associated skeletal and soft-tissue injuries. This trend approached statistical significance (p=0.137). In both groups, none of the patients had spinal cord injury, and in the atypical group two patients had C2 radiculopathy. Treatment outcome was assessed in 11 patients in the atypical group, and 7 patients in the typical group, with a minimal follow-up period of 6 months. In the atypical group 1 patient had C1-C2 fusion, 7 were treated in a halo-vest and 3 in a collar, and in the typical group 3 were treated in a halo-vest and 4 in a rigid collar. All patients in both groups had a successful radiographic union. The numbers of patients with available data regarding pain, neck range of motion and return to work was to small for statistical analysis. Discussion and conclusion: The atypical form of traumatic spondylolisthesis of the axis occurs in older patients than the typical form. Motor vehicle accidents are the cause of injury in the majority of cases. Skeletal and soft-tissue injuries are frequent and should be sought in every patient at the time of initial evaluation. Neurological injury in these fractures was infrequent. A prospective multi-center randomized controlled study is needed to determine the optimal treatment of choice in these fractures. 148 SURGICAL TREATMENT OF DISC HERNIATION IN THE ELDERLY G.J. Velan, G. Herling, C. Salame, I. Otremski The Souraski Tel Aviv medical Center, 6 Weitzman St, Tel Aviv, Israel Study design. A retrospective study of patients over 70 years of age who underwent discectomy at our institution. Objective. To study the clinical manifestations of disc disease in these patients, and the short-term perioperative complications of surgery. Summary of background data. Lumbar disc disease causing radiculopathy affects adults in their third to fifth decades. Lumbosacral radiculopathy or cauda equina syndrome due to disc herniation or protrusion are infrequent in octogenarians. There are only few small case series reporting the results of surgical treatment of disc disease in this age group, and in several reports these are mixed with the results of surgical treatment of spinal stenosis, which is more frequent in this age group. Most studies concluded that surgery is not contraindicated in these patients but the functional outcome is determined by the general health status and presence of co-morbidities. Methods: All charts of patients treated in our institution for lumbosacral radiculopathy between 1986 and 1999 were reviewed. The study included patients over 70 years of age, treated operatively for disc herniation. Patients who underwent laminectomy for spinal stenosis and had discectomy performed also, were excluded from the study. Results: There were 25 patients who met the inclusion criteria. Four patients were excluded for coexistence of spinal stenosis, in 4 patients the data in the charts was incomplete. 17 patients were included in the study, 16 had one surgical procedure performed and one patient had two procedures performed, each at a different level. Average age was 73.5 (range 70–83); there were 11 males and 6 females. Indication for surgery was cauda equina syndrome in 2 patients, neurological deficit without bladder or bowel dysfunction in 1, radiculopathy in 6, pain unresponsive to conservative measures for at least 6 weeks in 8. ASA grade was 1 in 5 and

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2 in 12 patients. All patients underwent laminectomy with disc space exploration and curettage; none underwent additional postero-lateral fusion and instrumentation. Operative complications included one dural perforation, there were no neurological complications, no cardiovascular complications no respiratory complications and no urinary tract complications. There was one occurrence of deep wound infection in one patient, treated satisfactorily by wound debridement and antibiotics. Average duration of postoperative stay was 3.5 days (Range 2–7 days). At a mean follow-up of 1.5 years (range 6 months to 2 years) 12 patients reported satisfactory alleviation of leg pain. All patients with neurological deficits had improvement but some dysfunction remained. Five patients have died 2 to 7 years after surgery, all of causes unrelated to surgery. Conclusion: Surgical treatment of disc herniation in the elderly is safe in properly selected patients. Surgery should not be denied of patients only due to their age, when surgical risk is acceptable. When accepted indications for surgery are met, results of surgery are generally good in the elderly. 149 SIGNIFICANCE OF NEUROPHYSIOLOGICAL AND URODYNAMIC INVESTIGATIONS IN PROGNOSIS AND TREATMENT OF SPONDILOGENIC MYELORADICULOISHEMIA A.A. Vishnevsky, O.V. Posohina, V.A. Fadeev, A.I. Gorelov, G. Bodgaradze Spine Center, Urology Department, Department of Functional Diagnostics, City Hospital No.2, Saint-Petersburg, Russia Syndromes of disorders in blood supplying the spine (Cones Sindrome – CS,Cauda Equina Syndrome- CES) are rare (about 1–2 %) complications of lumbardisk hernia (Kostuik J. et al., 1986, Coscia M., Leipzig T., Cooper, 1994).During the period from 1996 to 1999 in the Saint-Petersburg Center of spinesurgery the number of patients with CS and CES syndromes was 16, thatamounted 0,66% of the total number of patients operated as to lumbar diskhernia. The results of retrospective analysis of these 16 ills are presentedbelow.For visualization of compression of dura mater and roots there were used notonly spondilogram, positive myelogram, computer tomography scan, magneticresonance but also neurophysiological investigations (somatosensor evokedpotentials by stimulation of n.tibialis-SEP, stimulation EMG- SEMG, needlesEMG-NEMG). We used “Viking-IY” (Nicolet) equipment. Because disorders ofbladder function were revealed in cases of 14 patients (88.2%) weinvestigated urodynamics (urofloumetrya, cystometria) as before so afterthe operation.Investigation of SEMG diagnostic reduced the H-response and amplitude ofF-wave in cases of 14 patients (88.2%). The use of SEP showed the mostsignificant changes in latent periods and amplitude of N21 in cases of 11patients (68%). After decompression operation (hemy- or laminectomy,microsurgical decompression and discectomy) the normalization and conformityof neurophysiological and urodynamic parameters were obtained in cases of 9and 6 patients correspondingly, later in a year – of 12 and 8 patients. Conclusion: It is important that surgical intervention in cases of CS andCES is to be performed within 24 hours after revealing. Neurophysiological and urodynamic investigations allows to verify quantitatively the efficiencyof surgical treatment of lumbar spondilogenic myeloradiculoishemia. 150 INSTABILITY OF THE ADJACENT SEGMENTS AFTER LUMBOSACRAL SPONDYLODESIS A. von Strempel, R. Chudalla, A. Behra Orthopädisches Fachkrankenhaus Annastift Hannover Klinik III Heimchenstrasse 1–7, 30625 Hannover, Germany

Instability of the adjacent segments is reported as a complication after lumbosacral fusions. Instability is often accompanied by a chronic pain- disease. The purpose of this study was to evaluate the radiological signs of the adjacent segments after postero-lateral fusion. Materials and methods: 225 patients participated in the study. The average follow-up was 27 months, with a range from 12 – 96 months and a mean age of 54 years. All patients had chronic low back pain with lumbar disc degeneration. From 1990 – 1998 all patients were operated, using a hinged pedicle screw system providing a loadsharing effect between bone and implant. Pre- and postoperative after 3, 12, 24 and 36 months the patients underwent clinical and radiographic examinations, including standardized anteroposterior and lateral radiographs. The instability signs were defined as alteration of the disc space, spondylolisthesis, retrolisthesis and lateral shift. Results: We found two patients with spondylolisthesis grade I according to Meyerding as well as one with retrolisthesis and one with lateral shift. The loss of disc height measured 0.01% for the first adjacent segment and 0.005% for the second adjacent segment. There was a significant decrease of intervertebral disc space in 16 patients (7%). Conclusion: Comparable studies exist for rigid systems only. Referring to the same measuring methods, signs of instability appear more often using rigid systems compared to the use of dynamical systems.

151 ELECTRICAL STIMULATION AS A FUSION ADJUNCT: CELLULAR MECHANISMS W. Wang, S.R. Pollack, T. Brighton Departments of Orthopedic Surgery and Bioengineering, Univ. of Pennsylvania, USA Introduction: The signal transduction mediating the proliferative response of bone cells to a capacitively coupled (CC) field involves increased intracellular Ca2+ via introduction through cell membrane calcium channels. Combined magnetic fields (CMF) and inductive coupling (IC) also increase the proliferation of bone cells. In this study, it is hypothesized that the cellular mechanism that mediates the proliferative response in CMF and IC involves the release of calcium from intracellular stores. Methods: Six specific intracellular inhibitors were used in this study. Verapamil, a membrane calcium channel blocker; neomycin, an inhibitor of the inositol phosphate cascade; BPB, a phospholipase A2 inhibitor; TMB8, an inhibitor of Ca2+ release from intracellular stores; indocin, a prostaglandin synthesis inhibitor; and W7, a calmodulin antagonist, each at a concentration that did not interfere with cell proliferation in control rat femoral cell cultures. Total DNA was determined with and without the inhibitors in cell cultures stimulated by these three signals for two hours. Results: The effect of the various inhibitors on cell proliferation and the involved pathway of each signal are shown below: Table 1 The effect of inhibitors on cell proliferation Inhibitors

CC

CMF

IC

Indocin BPB TMB-8 W-7 Verapamil Neomycin

+* + – + + –

– – + + – –

– – + + – –

* + Indicates inhibitor prevented increased cellular proliferation

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Discussion: The mechanism of CC is different than IC and CMF. CC increases proliferation by opening voltage-gated calcium channels in the bone cell membrane, whereas IC and CMF bring about the release of calcium from intracellular stores. 152 RADIOLOGICAL RESULTS AFTER HARRINGTON ROD TREATMENT OF THORACOLUMBAR VERTEBRAL FRACTURES. A PROSPECTIVE LONG TERM FOLLOW-UP P. Wessberg, P. Nyberg, P. Neumann, A. Nordwall Department of Orthopaedics, Institute of Surgical Sciences, University of Göteborg, Sweden Introduction: There is still no concensus on the question of surgical or non-operative treatment of injuries to the thoraco-lumbar spine. Nor is the method of choice undisputed, when surgery is preferred. This is a prospective study of consequtively operated unstable injuries to the thoracolumbar spine at the departement of orthopaedics, Sahlgren University Hospital, Göteborg, focusing on the Harrington distraction rod method. Material and background: 156 patients were consecutively operated for this injury during the period of 1980 to 1988. They were followed with X-rays, postoperatively, at one year, and at follow five years or more after injury. Harrington distraction rods were used in 144 cases (84 men, 60 women). Mean age was 32. 134 were eligible for follow-up. 130 attended (97%). 97 had had there rods removed. Results: Fusion rate was 90%. Kyphosis angle was 16±1.0° (mean±sem) before injury, 0±0.7° postoperatively, 5±0.8° at one year and 12±0.7° at follow-up. The anterior vertebral height was 57±2 percent preoperatively, 88±1 postoperatively, 84±1 at one year and 86±1 at follow-up. If rods were removed the height was 84±1 while it was 92±2 when rods were in place. 8 cases had a sagittal displacement of 10 mm or moore (mean 26). End result was 1 mm. 18 cases had a scoliotic deformity of 10° or moore (mean 14°) with an end result of 3°. Conclusion: Harrington distraction rods, however today somewhat out of date, provides an effective way of restoring displacement of the vertebral body and alignment of the spine after a thoracolumbar injury. Vertebral height is somewhat better maintained if the rods are left in place. 153 BIOMECHANICAL IN VITRO COMPARISON OF TRANSS FOR INSTRUMENTATION OF SPINAL SEGMENTS H.J. Wilke, F. Magerl, S. Neller, F. Raible, E. Claes Dept. of Orthopaedic Research and Biomechanics, Helmholtzstrasse 14, D-89081 Ulm, Germany With translaminar facet screw fixation (TFSF) an average fusion rate of 96.2% (92%–100%) for mono- and bi-segmental treatments is reported. In some cases screw loosening (3%) or failure of the titanium screw (0.4%) were observed. Alternatively translaminar facet pin fixation (TLPF) has been suggested to reduce these risks. The aim of this study was to investigate whether pins can guarantee an adequate stabilizing effect compared to the screws. Following an in vitro test with 6 human cadaveric specimens, a second in vitro experiment with calf specimens was performed. Two groups with each 6 L3/4 specimens were instrumented with two translaminar steel screws or carbon fibre reinforced pins and loaded with pure moments of ±7.5 Nm in flexion/extension, lateral bending, and axial torsion. Range of motion (ROM) and neutral zone (NZ) were compared with the intact specimens. Normalized to the intact state (100%), the ROM median values of TLPF (TLSF) were reduced in flexion/extension to 32% (34%), in lateral bending to

39% (23%) and in axial rotation to 76% (74%). These trends were similar for the NZ (intact, TLPF, TFSF) which was normalized to the ROM of the intact spine: 16%, 6%, 7% in flexion/extension, 37%,12%,5% in lateral bending, and 8%, 8%, 8% in axial rotation. Except of lateral bending translaminar pins led to a similar primary stability as screws of instrumented lumbar calf segments and might serve as an advantageous alternative for the translaminar screw fixation. Due to large variations with human preparations we repeated the experiment with calf segments. 154 ANATOMIC CONSIDERATION FOR PERCUTANEOUS PEDICLE SCREW INSTRUMENTATION C. Wimmer1, C. Gegenhuber1, L. Kirchmair2, H. Maurer2 1Department of Orthopaedic Surgery, University of Innsbruck; 2Institute of Anatomy, University of Innsbruck, Anichstrasse 35, A6020 Innsbruck, Austria The anatomy of the lumbar spine from L1 to S1 was evaluated by anatomic dissection of 10 human cadaver spines. The aim of the study was to define the anatomic borders for a safe working canal to the pedicle of L1-S1 for percutaneous pedicle screw instrumentation. The dimension and the angle of the entrance into the pedicle between M.multifidus and M.longissimus are unclear in the literature. The canal entrance angle between M.multifidus and M longissimus for a canal was determined. The angle of entrance was called a. The angle a was measured by the formula of tan a. Tan a was defined by a-c/d. A was defined as the distance from the spinous process and to the intersection of a tangent to the M.multifidus. C was defined as a distance from the spinous process to the origin of M. multifidus on the pedicle. D was defined as a distance between a and c. One hundred and twenty dissection from level L1 to S1 were evaluated. Table 1 showing us the results from the distance a, c, d and the entrance angle a. Table 1 Anatomic measurement of the distance a, c, and d. level a (mm)

c (mm)

d (mm)

a (degrees)

L1 L2 L3 L4 L5 S1

19.6 (18.0–27.5) 23.1 (14.5–29.5) 23.7 (19.0–26.5) 25.3 (21.5–31.0) 27.4 (25.0–33.5) 28.9 (24.5–32.0)

24.3 (18.0–34.0) 30.8 (23.0–36.0) 33.1 (24.0–49.0) 34.5 (28.0–48.0) 34.4 (28.0–42.0) 30.5 (25.0–43.0)

–9.2 –1.7 +3.8 +5.6 +9.2 +18.6

15.5 (9.5–34.5) 22.1 (19.5–32.0) 25.9 (12.5–33.0) 30.8 (16.5–37.0) 33.0 (20.5–44.0) 39.2 (15.5–53.0)

We can conclude that there exists a safe working canal with the entrance angle a between the M. multifidus and M.longissimus from the medial side to the lateral side at the level L1 with 9 degrees and the level L2 with 2 degrees. At the level L3 to S1 a save working canal with the entrance angle a from the lateral side to the medial side at the level L3 with 4 degrees, at the levelL5 with 9 degrees, and at the level S1 with 19 degrees. 155 CONSERVATIVE TREATMENT OF TUBERCULOUS SPONDYLITIS C. Wimmer, B. Stöckl, M. Nogler, C.M. Bach Department of Orthopaedic Surgery, University of Innsbruck, Anichstrasse 35, A-6020 Innsbruck, Austria The purpose of the study was to evaluate the effect of conservative treatment on the angle of the gibbous deformity after >10 years and to evaluate the risk of increasing kyphosis. From 1969 to

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1985, we treated 48 cases of tuberculous spondylitis with chemotherapy and orthotic supports. Three of them had to be treated surgically because of progressing kyphosis. The kyphotic angle was measured according to Cobb. A line was drawn through the superior vertebral endplate of the upper vertebra, and the inferior vertebral endplate of the lower vertebra of the involved segment. The spinal segments involved ranged from T5 to L5. In four patients two vertebral bodies were affected with tuberculosis. The thoracolumbar spine was the common side of the tuberculous lesion. All patients were admitted to the hospital and had bedrest for 1–3 weeks. Patients were mobilized with a thoracolumbosacral flexion extension lateral rotatory plaster orthosis, which was fitted in reclining position. At the time of admission, the mean kyphosis was 18° (10–24°) in the thoracic spine, and 9° (3–22°) in the lumbar spine. This retrospective study is based on 40 patients (18 female and 22 male) with a mean follow-up period of 17 years (range from 10–26 years). 30 patients showed radiographically consolidated bony union, 2 showed incomplete fusion, and 8 showed no union. Only six patients without spontaneous fusion presented pain. The kyphotic deformity increased in the thoracic spine after 17 years follow-up of 3° (3–5°). Our results indicate that long-term outcome of conservative treatment is good with only a slight increasd kyphosis in patients without neurological deficit. Thus, conservative treatment is still an alternative to radical surgical treatment in cases with kyphosis<34° and no neurological deficit.

156 ASSESMENT OF SOMATOSENSORY EVOKED POTENTIALS DURING INTRAOPERATIVE MONITORING OF SPINAL CORD FUNCTION IN CONGENITAL AND SYSTEMIC DEFORMATION OF THE SPINE D. Winiarski, D. Zarzycki, A. Rymarczyk, K. Kacka, W. Sienkiel Zarkopane, Poland Introduction: Operative treatment of spinal deformities creates a huge risk of central nervous system injury leading to paraplegia inclusive. The purpose of this study was to evaluate the results of somatosensory evoked potentials (SEP) during intraoperative monitoring of spinal cord function in congenital and systemic deformation of the spine. Material and methods: 36 patients with mean age was 10 years and 2 months old (range 4 – 47 years) were selected for this study. Patients were divided into 4 groups considering the type of spinal deformity: 1) congenital scoliosis – 9 patients 2) congenital kyphosis and kyphoscoliosis – 7 patients 3) congenital scoliosis with dysraphic changes – 9 patients 4) scoliosis in systemic syndromes – 11 patients During 40 operative procedures the changes of latentia amplitude and shape of SEP diagrams were evaluated. Results: – In 25 cases operative and preoperative SEP–s were comparable. – In 6 procedures amplitude’s decrease following by its increase to preoperative values was observed. – In one case the total decay of responses of cortical potentials was stated. – During 4 operative procedure the constant decrease of responses’ amplitude over 50% in comparison to preoperative investigation was noticed. – In reoperations the return of responses in SEP were observed in 4 cases. Conclusion: The presented method of monitoring the spinal cord function allows for fast, objective, repeatable and relatively precise evaluation the impendence of integrality of ascendent tracts of spinal cord. The most sensitive coeffitient of pressure on spinal

cord is SEP’s responses amplitude, especially the first positive deflection (P37).

157 SURGICAL TREATMENT OF LUMBAR HYPERLORDOSIS IN SPINA BIFIDA PATIENTS S. Yalçin, C. Cabukoglu, N. Ozaras, B. Erol Marmara University School of Medicine Department of Orthopedics, Istanbul, Turkey Objective: Lumbar hyperlordosis produces a nonphysiological flexion posture and interferes with sitting and standing balance in children with spina bifida. This occurs mostly secondary to untreated hip flexion contracture in high lumbar involvement. The objective of this study was to present the results of surgical intervention followed by a short period of intensive rehabilitation on the sitting balance, ambulation status and lordosis angles. Design/setting: This was a prospective study in a series of 3 cases taken from the 314 patient cohort of Marmara University School of Medicine Spina Bifida Clinic. Materials/methods: We operated on three patients between the ages of 10 and 16. The preoperative lordosis angles were 140, 110 and 100 degrees. Single stage posterior spinal instrumentation and correction was applied with extensive release of facet joints, interspinous and interlaminar ligaments. A TLSO was used for three to four months. The follow-up period was between 12–24 months. Results: The postoperative lordosis angles were reduced to 80, 60 and 60 degrees respectively. In the two ambulatory cases extensive soft tissue release and proximal femoral osteotomy were needed to correct the hip flexion contracture. One of the patients regained sitting balance and was able to use her wheelchair while two others were able to walk using high braces after a period of intensive rehabilitation. Conclusion: Single stage posterior extensive release and spinal instrumentation provides satisfactory correction of the lordosis and when coupled with procedures to relieve hip flexion contractures satisfactory ambulatory status may be obtained.

158 KYPHECTOMY AND STABILIZATION WITH VERTEBRAL SCREWS IN SPINA BIFIDA S. Yalçin, M. Özek, C. Cabukoglu, A. Dagcinar, B. Erol Marmara University School of Medicine, Department of Orthopedics, Istanbul, Turkey Objective: Lumbar kyphosis is among the most important problems in spina bifida patients. These children experience problems with sitting and standing balance along with decubiti at the apex of the deformity. Historically these problems were addressed by kyphectomy and rod-wire techniques which required long segment instrumentation. Beyond the perioperative problems caused by a long incision these children face a nonphysiological short thoracolumbar spine because of the long segment instrumentation and fusion at a young age. In this study we tried to overcome these problems by applying short segment fusion with the aid of vertebral screws. Design/setting: This was a prospective study in a series of 6 cases chosen from the 332 patient cohort of our Spina Bifida Clinic. Materials/ Methods: We operated on six patients with thoracic spina bifida between the ages of three and seven with a combination of pediatric sized vertebral screws, rods or plates, wires and transvers connectors. The mean preoperative kyphosis angle was 105 degrees (80–130). In all patients relatively short segment instrumentation (average 4,8) was applied with satisfactory correction. Cast

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application was limited to two months. The follow-up period was between 32 –18 months. Results: The mean postoperative kyphosis was 14 degrees (0–32), loss of correction was negligible but in one case (30 degrees). Implant loosening at the cephalic side was revised in this case. Skin slough which healed with prolonged wound care was encountered in two patients in spite of the low profile screw-plate assembly. Sitting balance was obtained and the occurrence of apical decubiti was prevented in all patients. Conclusion: The application of vertebral screws in the reconstruction of the kyphotic spine is technically easy and provides more reliable fixation than wires and hooks. Furthermore short segment fusion may avoid the development of a short spine on long term but the risk of recurrence of the kyphotic deformity may remain. 159 SINGLE STAGE POSTERIOR VERTEBRECTOMY IN YOUNG CHILDREN FOR THE TREATMENT OF CONGENITAL KYPHOSIS AND SCOLIOSIS S. Yalçin, M. Ozek, C. Cabukoglu, A. Dagcinar, R. Yilmaz Marmara University School of Medicine, Department of Orthopedics, Istanbul, Turkey Purpose: To develop an efficient technique for the correction of congenital kyphosis and scoliosis. Significance: Historically the treatment for congenital spinal deformities consisted of observation, posterior or anterior fusion in situ and combinations of these. Two stage (anterior and posterior) hemivertebrectomy has become more popular in the last decades because this operation provides an acute correction of the deformity. Unfortunately this procedure has a high complication rate and is extremely difficult in certain segments. A single stage posterior approach will achieve the same correction avoiding complications of anterior surgery in young children. Methods: We have performed the Eggshell subtotal vertebrectomy in four patients with congenital deformities. The patients ages were (4, 5, 5 and 6), two patients had a congenital kyphosis (one Type I at T5–6, the other Type II at T12), the third and fourth patients had a fully segmented hemivertebra at L1 and a semisegmented hemivertebra at T12 respectively. In all patients the vertebrectomy was completed with a standart posterior approach, a novel compressive posterior instrumentation with rods and wires was applied to produce and maintain correction. A short segment (one level above – one below) posterior fusion was performed. Perioperative transfusion requirements were 250 and 500 ml (375 average). The duration of the operation was between 160 and 300 minutes (215 min. average). All patients were followed up with a fulltime TLSO for two months, day only bracing was prescribed till the end of the sixth month. Results: The average correction of the scoliotic and kyphotic curves was 38 degrees. In one case a minor ulcus at the end of a rod healed without further complications. The follow-up period was between 18 and 25 months (20.4 mo average). There were no considerable loss of correction at the last controls. Conclusion: We presume that single stage posterior vertebrectomy can be applied to a wide spectrum of congenital spine deformities to obtain correction and stability in young ages.

Introduction: Recently, there have been increasing the reports of involving neural compromise due to delayed vertebral body collapse after osteoporotic compression fractures. The aim of this study is to evaluate the clinical results of surgical treatment for vertebral body collapse with paralysis due to osteoporosis in thoracolumbar spine, retrospectively. Materials and methods: Since 1989 to 1998, 19 patients (7 men, 12 women) with paralysis due to osteoporotic vertebral collapse in thoracolumbar spine were surgically treated. All patients could be followed. The average follow-up period was 55 (24–128) months. Ages at surgery ranged 63–85 years (average, 75 years). The distribution of involved spine was T11 to L5 and T12, L1 were predominant. 4 patients were multilevel fractures. In 8 patients, Kaneda systems were used for anterior approach. In 11 patients, pedicle screw systems for posterior. The bone volume was 53.7Å}19.5 mg/cm3 (QCT). Neurological status was assessed with the Frankel classification. Results: Recovery using the Frankel classification was from grade C in 5 patients and grade D in 14 patients before surgery, to grade D in 5, and grade E in 14 after surgery. Loss of correction between at just after surgery and the final follow-up was 1.5 degrees in anterior approach, 20.5 degrees in posterior. Loosening of pedicle screws occurred in 6 patients. Conclusion: Compared with pedicle screw systems, anterior approach with Kaneda system allowed good neurological recovery and restored spinal stability for the treatment of osteoporotic fractures of single or two level in thoracolumbar spine. 161 IS ANTERIOR RELEASE IN ADOLESCENT IDIOPATHIC SCOLIOSIS (AIS) EFFECTIVE FOR ENHANCING THE RATES OF CORRECTION OF THE THORACIC CURVE IN ALL THREE PLANES? M. Yazici, A. Alanay, E. Acaroglu, V. Deviren, A. Surat Hacettepe University dep. of Orthopaedics and Traumatology 06100 Siihiye Ankara,Turkey Purpose: To evaluate the effectiveness of anterior release/fusion operations on enhancing the rates of surgical correction and preserving the obtained correction in frontal, sagittal and transverse planes. Patients and methods: Forty-one patients operated for AIS were evaluated prospectively with pre and post-operative and follow-up standing X-rays and CT rotation measuremets. Seventeen of these had undergone anterior release (A+PF) and fusion along with posterior fusion (PF) and segmental instrumentation because of curve rigidity or immaturity. Average patient age at the time of operation was 14.5±2.0 years, and average follow-up was 47.1±21.8 (24–96) years. Patients were evaluated for corrections obtained in frontal and transverse planes, changes in sagittal plane, and the rates of preservation of correction in A+PF and PF groups. Results: Average pre-operative frontal Cobb was found to be 57.0± 14.0 deg, thoracic kyphosis 32.8±22.7 deg, and apical rotation 15.7±8.8 deg, were corrected/changed to 20.1±10.6 deg, 37.5± 10.8 deg and 16.4±8.3 deg post-operatively and progressed to 23.9±10.7 deg, 41.3±12.7 deg and 16.6±10.6 deg at follow-up respectively. Curve flexibility was 44.7±22.5% in PF and 30.9± 19.9% in A+PF groups (p=0.29).Rates of correction by groups, analysed using ANOCOVA with curve flexibility as a co-factor, and correction loss (t-test) were as follows.

160 CLINICAL RESULTS OF SURGICAL TREATMENT FOR VERTEBRAL BODY COLLAPSE WITH PARALYSIS DUE TO OSTEOPOROSIS IN THORACOLUMBAR SPINE Y. Yasukawa, S. Akizuki, T. Takizawa, J. Kitahara, H. Itou, R. Gejou Department of Orthopaedic Surgery and Rehabilitation, Nagano Matsushiro General Hospital, Nagano, Japan, 183 Matsushiro Matsushiro town Nagano city, Japan 381–1231

Coronal correction (%) Coronal corr. loss (%) Change in kyphosis (%) Ap. rot. correction (%) Ap. rot. corr. Loss (%)

A+PF

PF

P-value

64.6± 17.7 6.7± 10.6 35.5± 63.8 –18.3± 26.8 86.8±198.7

65.2± 12.6 7.2± 10.7 –33.0±191.4 64.9±234.7 12.5± 34.6

0.000 0.214 0.292 0.534 0.164

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Discussion: Our results demonstrate that, the addition of anterior release to posterior fusion and instrumentation appears to be effective in achieving a substantial rate of coronal deformity correction in rigid curves. Any effects on thoracic kyphosis as well as the rotational deformity could not be demonstrated even when curve flexibility was taken into consideration. Furthermore, anterior fusion does not seem to be effective for preventing correction losses during follow-up period.

162 BONE GRAFT LOCATION HAS A MAJOR EFFECT ON INTERSEGMENTAL MOTION T. Zander, A. Rohlmann, C. Klöckner, G. Bergmann Orthopaedic Hospital of the Free University of Berlin, Oskar-Helene-Heim, Clayallee 229, 14195 Berlin, Germany In order to achieve spinal fusion, an intervertebral disc is often replaced by a bone graft. Graft size, location and elastic behaviour may vary widely. The aim of the analytical study was to determine the influence of these parameters on intersegmental motion and intradiscal pressure. A three-dimensional, nonlinear finite element model of the lumbar spine was created. Dorsal stabilization was established by bisegmental internal fixators bridging the L3 vertebra. Most of the L2/3 intervertebral disc was replaced by a bone graft. Three kinds of modifications were examined: i) Variation of the elastic modulus of the bone graft between 500 and 5000 MPa. ii) Grafts with three different cross-sectional areas. iii) Four different locations of the bone graft. Intersegmental motion and intradiscal pressure changes were calculated for flexion and lateral bending with pure moments of 3.75 Nm. The elastic modulus of the graft had only a negligible effect on intersegmental rotation and the intradiscal pressure. The bone graft size had only a minor effect on intradiscal pressure but led to a variation of 25% of the intersegmental angles for lateral bending. The greatest impact on the changes of the intersegmental angles had the bone graft location. For flexion, intersegmental rotation varied by 400% with the lowest value for a graft near the anterior rim of the vertebral body. The corresponding value for lateral bending was 60%. All eccentric bone graft locations caused additional bending perpendicular to the loading plane.

Results: In 7 patients after posterior fusion,the progress of neurological disorders was observed, in 2 cases stabilization of deformity was obtained. In 4 cases after anterior fusion progress of deformity was observed. In 1 patient after anterior fusion with instrumentation deformity’s correction and neurological stabilization was obtained, in second patient the progress of neurological disorders was observed -In 4 patients after vertebrectomy stabilization of deformity was obtained with regression of neurological disorders while in 3 cases different combinations of deformity’s progress and neurological changes occurred. Conclusion: Our findings revealed that only performed vertebrectomy and stabilization combined in one operative procedure ensures patients against progress of neurological disorders and deformity of spine.

164 SURGICAL TREATMENT OF CONGENITAL SCOLIOSIS DUE TO FORMATION FAILURE D. Zarzycki, B. Bakalarek, A. Rymarczyk, J. Jurkowski Department of Pediatric Orthopaedics and Rehabilitation, Jagiellonian University, College of Medicine, 34–500 Zakopane, ul. Balzera 15, Poland Introduction: Congenital spinal deformities in thoracolumbar spine are mostly a mixture of formation and segmentation failure combined with ribs abnormalities.The purpose of this study was to analyse retrospectively the role of surgical management in patients with congenital scoliosis due to formation failure. Material and methods: Between 1987–1997 42 patients with mean age was 8.5 years old, with average preoperative Cobb’s angle 57.8 were operated in our hospital. There were 25 patients with single hemivertebra and 17 patients with multiple hemivertebra and/or bars. Anterior and posterior vertebrectomy with spondylodesis was performed in 13 cases. Combined anterior and posterior fusion with instrumentation was performed in 29 cases. Results: After follow-up of 3 years the scoliosis were stabilized and the average Cobb’s angle was 48.98. Conclusion: Vertebrectomy with anterior and posterior fusion combined with instrumentation is a good method for stabilization of progresion. Operative procedure should be done much earlier than in our patients.

163 165 SURGICAL TREATMENT OF CONGENITAL VERTEBRAL DISPLACEMENT D. Zarzycki, B. Bakalarek, M. Kalicinski, A. Rymarczyk, A. Winiarski Department of Pediatric Orthopaedics and Rehabilitation Jagiellonian University, College of Medicine, 34–500 Zakopane, ul. Balzera 15, Poland Introduction: The essence of this pathology is congenital structure’s defect including a vertebrae and disc with instant curvature of the vertebral canal. The purpose of this study was to evaluate the effectivenes of surgical treatment of CVD and establish the optimal operative management. Material and methods: 12 patients with mean age was 6 years and 8 months (range 2–18 years) were operated. Two patients were treated conservatively.The observation’s period was 4 years and 9 months on the average (range 1–11 years). Two types of CVD were specified: type A- 9 patients, type B- 5 patients. Surgical techniques performed: posterior fusion – in 7 patients; posterior fusion with instrumentation – in 1 case; anterior fusion – in 4 patients; anterior fusion with instrumentation – in 2 cases; vertebrectomy with anterior fusion – in 7 patients.

CERVICAL SPONDYLOTIC MYELOPATHY: COMPARISON OF OUTCOME FOLLOWING CIRCUMFERENTIAL VERSUS ANTERIOR DECOMPRESSION & FUSION G. Zaveri, M. Ford, M. Vidmar University of Toronto, Canada Introduction: Cervical Spondylotic Myelopathy has traditionally been managed by anterior or posterior decompression with/without fusion. More recently, a 360° operation has been suggested in selected patients with CSM, to permit better neurological recovery & relief of axial and radicular symptomatology. This study compares the clinical & radiological results following circumferential versus anterior decompression and fusion for CSM. Material & methods: Fifteen patients who underwent a 360° operation (Group1) for CSM were matched for age, number of levels operated and follow-up duration, with patients (Group 2, n=15), that underwent anterior decompression and fusion by the same surgeon. An independent, retrospective review of charts and radiographs was conducted. At a final follow-up (mean 3.4 years) in December 1999, patients completed an AAOS Cervical Spine questionnaire.

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Results: Patients who underwent the circumferential operation showed quantitatively (measured using the mJOA Myelopathy Scale) and qualitatively better neurological improvement compared to those that had an anterior surgery alone. 87% of those in group1 and 67% in group2 showed improved function. However, the improvement in the mechanical neck pain was comparable between the two groups as was the satisfaction with treatment. There was no significant difference in the complication rate or adjacent

level degeneration. The incidence of graft and hardware related problems was slightly higher in group 2. Conclusion: Single stage circumferential spinal decompresssion and fusion is a relatively safe procedure, resulting in consistent neurological recovery in selected patients with cervical spondylotic myelopathy. However persistence or appearance of new mechanical neck pain can be a distressing problem.