International

International Orthopaedics (SICOT) (1989) 13:39-45

Orthopaedics © Springer-Verlag 1989

Laminopediculoplasty: a new method of reconstructing the posterior elements of the thoracic spine N. Tsuzuki, H. Tanaka, and A. Seichi Department of Orthopaedic Surgery, Saitama Medical Centre, Saitama Medical School, 1981 Tsujido-cho, Kawagoe, Saitama, Japan

Summary. We describe a new method o f reconstructing the posterior elements o f the thoracic spine following decompression o f the cord through a wide posterior approach. Osteoperiosteal corticocancellous grafts are harvested from the iliac wing, then bent into a semicircle with the periosteum on the inside and inserted between the resected vertebral pedicles where they act as a base for further grafting. The posterior spinoligamentous complex is preserved and reattached. This technique permits circumferential decompression o f the thoracic cord through a posterior approach and posterior thoracic interbody fusion. Fifteen patients were treated by this method and a solid fusion achieved in each case. No bony ingrowth into the spinal canal was observed. R6sum/~. Les auteurs d~crivent un nouveau procbd~

de reconstruction de l'arc post~rieur du rachis dorsal aprds dkcompression mkdullaire par une large voie d'abord postbrieure. Un greffon ostko-p~riostk, cortico-spongieux, prblevb sur l'aile iliaque, est encastr~ entre les p~dicules vertdbraux rksbqubs, formant un arc, le p~rioste vers l'avant. II peut servir de support ~ une greffe complkmentaire, joignant les lames sus et sous-jacentes & la laminectomie. "Habituellement on conserve l'apophyse bpineuse et ses ligaments et on la replace en arridre du greffon. La paroi post~rieure du canal rachidien ainsi reconstruite consolide en trois ~ six mois et donne une bonne stabilit& Cette technique permet une dbcompression mkdullaire circonfbrentielle, ainsi qu'une arthrodOse corporkale des vertObres dorsales, par une vole d'abord postbrieure. Quinze malades ont

Offprint requests to: N. Tsuzuki

bt~ traitks par cette m~thode, la consolidation a bt~ obtenue dans tousles cas. II n'y a pas eu d'ossification endo-canalaire.

Introduction A c c e s s to t h e b a c k o f t h e t h o r a c i c v e r t e b r a l b o d i e s t h r o u g h a w i d e p o s t e r i o r a p p r o a c h is g a i n e d at t h e e x p e n s e o f s p i n a l s t a b i l i t y . I f t h e p o s t e r i o r elements can be reconstructed and stability reestablished, a circumferential decompression of the thoracic cord may be achieved through a single p o s t e r i o r a p p r o a c h . W e r e p o r t f i f t e e n c a s e s in which an osteoperiosteal iliac graft has been used for this purpose.

Operative technique We define a wide posterior approach as one in which, after detachment of the posterior spinoligamentous complex (Fig. 3), there is extensive excision of the posterior elements including laminae, facet joints, and the medial two-thirds of the pedicles, the lateral third being preserved as a base for reconstruction. In our experience, the presence of the lateral wall of the pedicle does not restrict access to the cord which, with the exception of its most anterior part, can be approached through a 1.5 cm channel on each of its sides. The extent of the resection is determined by the degree of decompression desired. Anterior decompression of the thoracic cord using this approach is not an established technique, and presents many problems. The lateral part of the bony mass causing the compression may be seen and excised without displacing the cord; the most anterior central one-third is approached from the side. The anterior part of the canal is first deepened with an air drill. Then, with an angled drill and curettes, the base of the remaining bone mass is removed little by little, leaving untouched that part of the bone in contact with the anterior dura. The remaining portion is then gently freed from the vertebral body and dural tube and removed. Any remaining anterior component may be seen and excised by displacing the freed

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Outer ~ cortex

N. Tsuzuki et al. : Laminopediculoplasty: a nev~ method of reconstructing the thoracic spine

~

Muscle Cancelousbone I ~ Innercortex

A

Fig. 1 A - C . Method of obtaining the osteoperiosteal graft. A A thin corticocancellous graft with the periosteurn intact is taken from the outer eorticocancellous portion of the iliac wing; B Photograph of the procedure; C The flexibility of the graft is shown Thoracic Spine Greenstick Fracture

Fig. 2A, B. Reconstruction of the posterior elements of the spine. A Patterns of laminopedicloplasty; B Sites for grafting. The spinous process-ligament complex is replaced on a new lamina.

dural sac. In our experience gentle displacement of the cord by less than one-third of its diameter does not cause damage. If the posterior longitudinal ligament is ossified and stuck to the dura, removing it risks damage to the cord. In these cases we advise deepening the spinal canal in front of the ossified ligament and allowing it to drop forward into the space created, as described by Ohtsuka et al. [3]. If a significant portion of the dura is ossified, we open the dural tube and keep it expanded with a fascial patch. When both dura and cord are involved, a simple posterior enlargement of the dural tube may not decompress the front of the cord. In these cases the dura should be carefully resected along with the ossified posterior longitudinal ligament (Fig. 4). The degree of anterior decompression may be checked intraoperatively by ultrasound (Fig. 6). Reconstruction of the posterior elements proceeds in the following manner. A thin corticocancellous osteoperiosteal graft is taken from the outer aspect of the iliac crest and bent into a semicircle of some 4 cm diameter, with the periosteum on the inside (Fig. 1). Next, if anterior decompression has been undertaken, a posterior thoracic interbody fusion is carried out at the affected levels (Fig. 2 B). The curved graft is then fitted over the cord between the two pedicles. If the graft is not flexible enough, it may be applied obliquely or transversely after reconstructing the pedicle with a bone peg (Fig. 2A). Further interlaminar bone graft is then applied and the posterior spinoligamentous complex reattaehed to the laminae immediately above and below the decompression (Fig. 2 B). The decompression and posterior element reconstruction at three vertebral levels takes between three and four hours to complete with a blood loss of 500-1000 mls. Postoperatively, the patient is nursed in a plaster bed for the first four to six weeks before being allowed up in a rigid

N. Tsuzuki et al. : Laminopediculoplasty: a new method of reconstructing the thoracic spine

41

In six cases the cord was compressed posteriorly by ossification of the ligamentum flavum (cases 8, 9, 12, 14) or tumour (cases 5 and 10) and required only a wide posterior approach: the other nine needed a circumferential decompression (Table 1). Kyphosis was caused by compression fractures in four cases, and tuberculosis and operative destabilisation in one case each. The average follow-up was fourteen months (range 4- 21 months).

Results

Fig. 3. The spinous process-ligament complex is preserved before laminectony.

D

A

C

E

Fig. 4A-E. Anterior decompression of the thoracic cord through the wide posterior approach. A Area of bone resected; B Bony remnant separated from the anterior dura; C Where bony remnant cannot be separated from the dura, both allowed to fall forward into prepared cavity; D Expansion of involved dura with a patch; E Resection of involved dura and posterior longitudinal ligament

Table 1. Causes of thoracic myelopathy Conditions causing kyphosis (Compression fracture 4 Tuberculosis 1 Postoperative sponylolisthesis 1) Spondylosis Ossification of the ligamentum flavum Ossification of the posterior longitudinal ligament Tumour

6

2 4 1 2

spinal brace. This is changed for a semi-rigid brace at twelve weeks and discarded after twenty-four. Solid bony fusion is usually obtained in three to six months. Patients

Fifteen patients aged between thirty-nine and seventy-six years (mean 54 years) were treated by decompression of the thoracic cord through the wide posterior approach, and reconstruction of the posterior elements by laminopediculoplasty (Table 1).

T h e results o f surgery are s u m m a r i s e d in T a b l e 2. Fusion was t h o u g h t to be satisfactory on radiological criteria after three m o n t h s , but a spinal b r a c e was w o r n for six m o n t h s for a d d i t i o n a l security. E a c h p a t i e n t h a d a solid fusion a n d a stable spine after six months. Pain was m i n i m a l or a b s e n t at the site o f o p e r a t i o n , with little or no spinal c o r d irritation on percussion. N o n e w b o n e f o r m a t i o n within the spinal canal has b e e n o b s e r v e d to date. Figures 5 - 7 show illustrative cases. N e u r o l o g i c a l i m p r o v e m e n t o c c u r r e d in twelve cases (80%) a n d m i x e d i m p r o v e m e n t a n d deterioration in two cases. O n e patient was u n c h a n g e d . A p o o r n e u r o l o g i c a l o u t c o m e was associated with d e l a y e d o p e r a t i o n after the onset o f s y m p t o m s , revision surgery with a d h e s i o n s a r o u n d the c o r d a n d a dense n e u r o l o g i c a l lesion on p r e o p e r a t i v e examination.

Discussion

A l t h o u g h a wide p o s t e r i o r a p p r o a c h to the spine m a y result in instability, there are a n u m b e r o f adv a n t a g e s in a p p r o a c h i n g the c o r d f r o m b e h i n d r a t h e r t h a n in f r o n t or f r o m the side (by costot r a n s v e r s e c t o m y ) . P r o b l e m s f r o m a t h o r a c i c or abd o m i n a l a p p r o a c h are a v o i d e d , the s e g m e n t a l b l o o d s u p p l y to the c o r d is p r e s e r v e d a n d it is possible to gain access to m o s t o f the c i r c u m f e r ence o f the dural sac. A n u m b e r o f surgeons h a v e carried out procedures on the a n t e r i o r p a r t o f the t h o r a c i c c o r d t h r o u g h a p o s t e r i o r a p p r o a c h [1, 2, 3, 4]. J e f f e r s o n a d v o c a t e d a unilateral wide p o s t e r i o r a p p r o a c h for the r e m o v a l o f t h o r a c i c disc p r o t r u s i o n s [2]. O u r t e c h n i q u e affords a better e x p o s u r e resulting in less m a n i p u l a t i o n o f the cord. O h t s u k a ' s m e t h od o f bilateral wide p o s t e r i o r d e c o m p r e s s i o n is excellent a n d we follow his principles, but his m e t h o d o f spinal stabilisation b y i n t e r t r a n s v e r s e fusion fails to p r o v i d e b o n y p r o t e c t i o n for the spinal c o r d a n d m a y n o t be strong e n o u g h to withstand external forces w i t h o u t a d d i t i o n a l spinal ins t r u m e n t a t i o n . In this series i n s t r u m e n t a t i o n was

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N. Tsuzuki et al.: Laminopediculoplasty: a new method of reconstructing the thoracic spine

Table 2. Clinicopathological details of the patients who had decompression of the thoracic cord and laminopedicloplastic reconstruction Case No./Sex/ Age (years)

Pathological condition of the spine

Operative procedures

Followup period (months)

Spinal stability

l/F/50

T4/5 displacement

C, T4-6 L-P plasty

21

Stable

2/F/39

T4/5 kyphosis

C, T4-5 L-P plasty

20

Stable

3/M/51

T11/12 fracture C, T11-12 L-P plasty dislocation (complete paraplegia)

18

Stable

4/M/16

T7/8 osteophyte

C, T7-8 L-P plasty

18

Stable

5/F/60

T11-12 meningioma

P, T11-12 L-P plasty

16

Stable

6/M/65

T5/6 T 7 / 8 0 P L L

C, T5- L-P plasty

15

Stable

7/M/65

T8/9/10 osteophytes C, T8-9 L-Pplasty

15

Stable

8/F/47

T10/ll OLF

P, T10-11 L-Pplasty

14

Stable

9/M/50

T 1 0 / l l OLF

P, TI0-11 L-Pplasty

13

Stable

10/F/48

T l l osteochondroma P, Tl1-12 L-P plasty

13

Stable

l 1/F/47

T11 compression fracture

C, T11-12 L-P plasty

12

Stable

12/M/60

T10/11 OLF

P, T10-11 L-P plasty

10

Stable

13/F/76

T11 compression fracture

P, T11-12 L-P plasty

9

Stable

14/M/60

T9/10 OLF

P, T9-10 L-P plasty

8

Stable

15/M/65

T l l compression fracture

C, Tll-12 L-P plasty

4

Stable

OPLL: ossification of the posterior longitudinal ligament OLF: ossification of the ligamentum flavum C: circumferential decompression of the spinal cord P: wide posterior decompression of the spinal cord L-P plasty: laminopedicoplasty M: motor S: sensory

Neurological symptoms Postoperative status Preoperative status (duration of symptoms before operation) Incomplete paraplegia M: one leg became wheel chair (2 years) weaker, other leg unchanged S: slightly improved Complete paraplegia M: unchanged with radicular pain S: radicular pain T4-5 (9 years) subsided M: unchanged Traumatic complete S: radicular pain paraplegia with subsided radicular pain T11-12 (6 years) M: slightly improved Unstable spastic (ankle clonus gait (4 years) decreased) S: unchanged Incomplete paraplegia M & S: improved free crutch gait (4 years) gait Incomplete paraplegia M: one leg became crutch gait (5 years) weaker, spasticity decreased in other leg S: unchanged Incomplete paraplegia M & S: improved free wheel chair (3 months) gait Unstable spastic M: improved free gait gait (3 years) Unstable spastic gait M: unchanged radicular pain S: radicular pain T10-11 (6 years) subsided Unstable spastic M & S: improved free gait (3 months) gait Incomplete paraplegia M: improved crutch wheel chair (1 year) gait S: improved M: improved crutch Unstable spastic gait wheel chair (3 years) gait S: improved Incomplete paraplegia M: improved able to stand up bedridden, painful S: paresthesia paresthesia (2 years) subsided Incomplete paraplegia M & S: unchanged wheel chair (6 years) M:improved Unstable spastic spasticity decreased gait (6 years) S: unchanged

N. Tsuzuki et al.: Laminopediculoplasty: a new method of reconstructing the thoracic spine

43

Fig. 5 A - D . Case 4. 46 year old man with thoracic myelopathy from an anterior osteophyte. A Preoperative CT myelogram; B Wiring of a curved graft to the remnant of the T7 lamina; C and D Postoperative CT scan and lateral tomogram showing the new lamina and overlying bone chips, and the graft in the disc space

only used in one case of complete traumatic paraplegia (Case 9). From our initial experience it was clear that preservation of the anterior longitudinal ligament and the outer shell of the vertebral bodies provided sufficient stability to turn the patient postoperatively. Since each patient was paraplegic before operation and took two to three months to recover afterwards, instrumentation was not needed to stabilise the spine for mobilisation though it may be needed in future to shorten the period of bed rest, in which case Luque rods or Roy-Camille plates would seem appropriate. The main intraoperative complication was fracture _of the graft while attempting to bend it. The interpedicular distance after resecting the me-

dial two-thirds is about 3 cm in the average Japanese adult. In an elderly patient, the graft can be bent to shape without difficulty, but in younger patients with stronger bone, fitting the graft into such a narrow space was sometimes impossible. In these cases the grafts were either applied obliquely or transversely after reconstructing the pedicles with a bone peg, or were gently fractured in several places to achieve the desired curve (Fig. 2). Our longest decompression spanned three vertebral levels, and this appears to be the largest defect that can be grafted from a single iliac wing. To date, we have seen no bony ingrowth into the spinal canal on computerised tomography. We usually leave a space of some 5 mm or more

44

N. Tsuzuki et al.: Laminopediculoplasty: a new method of reconstructing the thoracic spine

Fig. 6 A - E . Case 11.47 year old woman with a T l l compression fracture. A Preoperative tomomyelogram; B Postoperative tornogram; C At operation the cord is widely decompressed. The tape passes through the cavity created by resecting the encroaching edge of the compression fracture; D Intraoperative ultrasonogram. The space between X and x represents the spinal cord. Despite resection of the compression (O), the cord did not recover its normal contour. After opening the dura, an adhesive arachnoiditis around the cord was found; E CT scan ten months after operation

Fig. 7 A - C . Case 9. Fifty year old man with ossification of the ligamentum flavum at TI0/11. A and B Preoperative appearance showing compression of the cord from the dorsal aspect ( , ) ; C Postoperative CT scan showing laminoplasty ('k), peg pediculoplasty (*), replaced spinous process ( ~ ) and bone chips on the lamina (O)

around the dural tube, which we think is enough to prevent cord compression should the laminae thicken up with time. Improvements in the neurological condition were presumed to depend on the preexisting con-

dition of the cord and its vulnerability to damage at operation, the extent and density of surrounding adhesions and the capacity of the cord to enlarge from postoperative oedema without further compression.

N. Tsuzuki et al. : Laminopediculoplasty: a new method of reconstructing the thoracic spine

These results indicate that our method of using a wide posterior approach with reconstruction by laminopediculoplasty gives satisfactory stability of the spine even after extensive excision of the posterior elements. This makes wide circumferential decompression of the thoracic cord possible from a posterior approach. References 1. Carson J, Gumpert J, Jefferson A (1971) Diagnosis and treatment of thoracic intervertebral disc protrusions. J Neurol Neurosurg Psychiat 34:68-77

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2. Jefferson A (1975) The treatment of thoracic intervertebral disc protrusion. Clin Neurol Neurosurg 7 8 : 1 - 9 3. Ohtsuka K, Terayama K, Tsutiya T, Wada K, Ohkubo M (1983) A surgical procedure for the anterior decompression of the thoracic spinal cord through the posterior approach. Orthop Trauma Surg 26: 1083-1090 4. Patterson R, Arbit E (1978) A surgical approach through the pedicle to protruded thoracic discs. J Neurosurg 48: 768-772