Knee Surgery ] Sports Traumatology ] Arthroscopy ]
Knee Surg, Sports Traumatol, Arthroscopy (1995) 3:14-17
9 Springer-Verlag 1995
Anterior cruciate ligament patellar tendon reconstruction: it is probably better to leave the tendon defect open! G. Cerullo 1, G. Puddu 1, E. Gianni 1, A. Damiani 2, F. PigozzP 1Clinica Valle Giulia, Via De Notaris 2 B, 1-00197 Rome, Italy 2 Department of Computed Tomography, Santa Maria di Collemaggio Hospital, L'Aquila, Italy 3 Superior Institute of Physical Education, Rome, Italy
Abstract. The purpose of our prospective study was to establish whether or not in anterior cruciate ligament (ACL) patellar tendon reconstruction the tendon defect has to be closed. In 50 consecutive ACL patellar tendon reconstructions, the tendon defect was randomly closed (group I) or left open (group II). The following data were recorded from all patients on the 4th and 14th days post operation: range of motion (ROM), pain at rest, pain and validity at isometric contraction, ability of bent leg raising (at 4th day) and straight leg raising (at 14th day). All the patients underwent ultrasonographic examination after 3 months and X-ray scanning at 6 months post operation. Forty patients underwent a CT-scan examination at 6 months. Thirty patients underwent isokinetic testing between 10 and 12 months post operation. Evaluating the immediate post operation data, no statistically significant differences emerged between the two groups. Ultrasonography showed in 68% of the knees of group I (defect closed) a thickened patellar tendon (PT), while in 60% of group II it was of normal thickness. No patients of either group developed patella infera by X-ray evaluation 6 months post operation. CT scans at 6 months showed that i00% of the knees of group I had a thickened PT in toto (nearly twice as thick as normal). Scar tissue was present not only in its central third but also in more than half of the cases in the medial and lateral third. In group II 75~ of the patients had a normal thickness PT and 25% presented with only a minimal thickening. Scar tissue was distinguished only at its central third. Some 32% and 36% of the patients of group I and II, respectively, developed patellar irritability between the 5th and 8th month post operation. Isokinetic tests performed between the 10th and 12th months showed that the quadriceps deficit was slightly less in group II than in group I. Our study did not show very important clinical differences between the two groups but revealed that if the tendon defect is closed, an exuberant scar process arises involving the entire PT. This could mean, as reported in the literature, a high reduction in the biomechanical properties of the PT. For this reason it is "probably" better to leave the defect open. Correspondence fo: G. Puddu
Key words: Anterior cruciate ligament - Patellar tendon reconstruction
Introduction The bone-patellar tendon-bone technique is today the most popular procedure for anterior cruciate ligament (ACL) reconstruction for many reasons: high tensile strength [6, 16], its ability to revascularize [1], good fixation [14] and especially good results at long-term followup [12, 13, 17, 22]. Not rare, however, are the reports about the complications of this procedure and its potentially detrimental effects on the extensor mechanism [4, 9, 13, 18-20, 23, 25]. The surgical technique is now standardized for either the arthroscopically aided technique [11, 24] or for intra-articular reconstruction [2]. However, the literature does not answer the common question: does the patellar tendon (PT) donor site have to be closed or not? To our knowledge, only two papers have tried to answer it. Eilerman et al. [8], in cadavers, studied only the patellofemoral contact pressure and concluded that it is not influenced by either closing or not closing the defect. Shaffer and Tibone [21] examined only the PT length, finding that closure does not significantly contribute to PT shortening. Our goal was to provide this answer, via a prospective, randomized study based on clinical findings, ultrasonography, computed tomography (CT) and isokinetic test.
Materials and methods Fifty consecutive, arthroscopically assisted, mid-third PT reconstructions were performed at our clinic between 1 September and 15 December 1992. The tendon defect was randomly closed (group I, n = 25) or left open (group II, n = 25). In group I the defect was closed using three full-thickness, simple, interrupted, 0 Vycril sutures, followed, when possible, by peritenon closure in the same manner. In group II the tendon defect was left open, suturing only, when possible, the peritenon. The skin incision was similar in both groups and lay centrally over the PT. The peritenon was also split centrally and divided from the central third of the PT.
15 Group I consisted of 21 men and 4 women; their average age was 23 years (range 18-34). Group II consisted of 22 men and 3 women; their average age was 24 years (range 17-31). All 50 patients were involved in sports. The postoperative regimen was the same in both groups, including immediate initiation of continuous passive motion, full weight-bearing after 30 days, cycling and swimming after 2 months, jogging with brace after 3 months. Return to a low-risk sport was allowed with brace after 7 months and to strenuous activities after 9-10 months. None of the patients practised isokinetic strengthening. We recorded the following data: pain at rest and during flexion, range of motion (ROM), ability of bent leg raising (BLR) on the 4th day post operation and ROM, validity of isometric quadriceps contraction, ability of straight leg raising (SLR) on the 14th day post operation. After 3 months, all the patients underwent ultrasonography at the Superior Institute of Physical Education of Rome, using a scanner Concept 2000 Dynamic Imaging (Livingstone, UK) provided with a 7.5-MHz linear array probe. Both longitudinal and transverse projections were used to investigate the PT, and the contralateral knee was examined for comparison. After 6 months 40 patients (20 from each group) underwent lateral comparative X-rays to study patellar height, using the methods of Insall and Salvati [10] and Blackburne and Peel [3]. Also at that time 40 patients (20 from each group) underwent CT at Santa Maria di Collemaggio Hospital of L'Aquila. Axial 2-mm slices were taken of the operated knees by a Somaton 2 scanner (Siemens, Erlangen, Germany) to study the patellar tendon. Ten patients did not undergo this examination because they did not give their consent. Between 10 and 12 months post operation, 30 patients (15 in each group) underwent isokinetic testing at the Superior Institute of Physical Education in Rome. Isokinetic testing was performed using a Merac machine (Universal, Cedar Rapids, Iowa) at 60 and 240 deg/s. Comparisons were made between the involved and noninvolved extremity. Before the test, the circumference of both thighs was measured at 15 cm above the upper pole of the patella.
Results On the 4th p o s t o p e r a t i v e day, the clinical e v a l u a t i o n s h o w e d that only 1 patients from each group had pain at rest; a v e r a g e R O M was 5 0 - 7 0 ~ in both groups, and 23 (92%) patients per group were successful in BLR. Six patients (24%) in group I and 7 patients (28%) in group II c o m p l a i n e d o f anterior knee pain during flexion. On the 14th p o s t o p e r a t i v e day, 2 patients in group I and 4 in group II s h o w e d a m i l d subcutaneous h a e m a t o m a that did not require any treatment. Ten patients (40%) in group I and 14 patients (56%) in group II c o u l d do strong isometric contractions o f the quadriceps, w h i l e the others could only contract weakly. N i n e t e e n patients (76%) in group I and 22 patients (88%) in group II were successful in SLR. R O M was: average extension 3.6 ~ (range 0 ~ ~ in group I and 3.2 ~ (range 0 ~ ~ in group II; a v e r a g e f l e x i o n 101 ~ (range 8 0 ~ ~ in group I and 98.5 ~ (range 80~ ~ in group II (Table 1). A l l 50 patients u n d e r w e n t u l t r a s o n o g r a p h i c e x a m i n a tion at 3 m o n t h s p o s t operation. In group I 8 patients (32%) had a n o r m a l thickness o f the i n v o l v e d PT, 5 patients (20%) h a d a P T t h i c k e n e d about one and a half times, 12 patients (48%) h a d a P T t h i c k e n e d about twofold. F i f t e e n P T (60%) were h y p o e c h o i c . In group II 15 patients (60%) had a n o r m a l thickness o f the PT, 2 pa-
Table 1. Range of motion on 14th day post operation (in numbers of patients) Extension Group I Group II
0~ 11 14
5~ 10 7
10~ 4 3
15 ~ 0 1
Flexion Group I Group II
80/85 ~ 2 2
90/95 ~ 8 9
100/105 ~ 110/115 ~ 120 ~ 7 7 1 10 4
Table 2. Patellar tendon ultrasonography at 3 months post operation (in numbers of patients) Group I
Group II
Thickness Normal Augmented 50% Augmented 100%
8 (32%) 5 (20%) 12 (48%)
15 (60%) 2 (8%) 8 (32%)
Echogenicity Normal Near normal Hypoechoic
1 (4%) 9 (36%) 15 (60%)
0 15 (60%) 10 (40%)
tients (8%) had a PT t h i c k e n e d about one and a half times, 8 patients (32%) h a d a PT t h i c k e n e d about twofold. Ten PT (40%) were h y p o e c h o i c (Table 2). Eight patients (32%) in group I and 9 in group II ( 3 6 % ) d e v e l o p e d p a t e l l a r irritability b e t w e e n 5 and 8 m o n t h s p o s t o p e r a t i o n ( p a i n at the l o w e r p o l e o f the patella during exercise). A t 6 m o n t h s post operation 40 patients (20 from each group) u n d e r w e n t lateral 45 ~ knee r a d i o g r a p h s bilaterally and CT. N o knee s h o w e d significant shortening o f the PT in either group on radiographs. C T revealed, however, that in group I all the PT were thickened: 14 PT (70%) were t h i c k e n e d nearly t w o f o l d and 6 PT (30%) were thickened about one and a half times. The width o f the tendon was about 15% less than normal. Scar tissue was present not only in the central third o f the patellar tendon, but also in m o r e than h a l f o f the m e d i a l and lateral thirds. In group II, 15 PT (75%) were n o r m a l in thickness, and 5 PT (25%) s h o w e d just slight thickening. T h e width of the tendons was normal, and scar tissue was present only in their central third. B e t w e e n 10 and 12 months p o s t operation the difference b e t w e e n the c i r c u m f e r e n c e s o f both thighs, m e a s u r e d 15 c m a b o v e the upper p o l e of the p a t e l l a , was calculated in 15 patients per group before testing t h e m on the isokinetic machine. In group 1 4 patients had the s a m e circumf e r e n c e , 6 patients h a d 1 c m less than the contralateral side, 4 patients 2 c m less and 1 patient 3 c m less. Also, 3 patients with 1 c m less and 2 patients with 2 c m less in thigh c i r c u m f e r e n c e had not yet returned to sports or h a d a b a n d o n e d in the last m o n t h s any exercise to maintain a g o o d t r o p h i s m o f the m u s c l e s (untrained patients). In group II 5 patients had the s a m e thigh circumference, 6 patients had 1 c m less than the contralateral side, 3 pa-
16 Table 3. Thigh circumference (difference in centimeters vs the contralateral side) measured 15 cm above the upper pole of the patella, in the 30 patients before they underwent isokinetic testing between the 10th and 12th months post operation (in numbers of patients) Difference
0
-1
-2
-3
Group I Group II
4 5
6 (3) 6 (1)
4 (2) 3 (3)
1 1 (1)
In parentheses is the number of patients who had abandoned in the last months any exercise to maintain a good muscular trophism
tients 2 cm less and 1 patient 3 cm less. In this group, untrained patients included 1 with 1 cm of hypotrophy, 3 patients with 2 cm and 1 with 3 cm (Table 3). At the two chosen speeds, isokinetic testing revealed that torque and work of quadriceps of the involved knee decreased in both group. In particular, the average deficit of the average torque of quadriceps was in group I 6.8% (range 13% to - 3 % ) at 240~ and 11.3% (range 22% to - 5 % ) at 60~ in group II it was 5.5% (range 20% to - 6 % ) at 240~ and 9.3% (range 24% to 0%) at 60~ The average deficit of the average work of quadriceps was in group I 9.5% (range 25% to 0%) at 240~ and 8.7% (range 18% to 3%) at 60~ In group II this was 6.2% (range 13% to 4 % ) at 240~ and 10.4% (range 24% to 1%) at 60~
Discussion The primary objective of the current study was to establish whether in A C L mid-third PT reconstruction it is better to close the tendon defect or leave it open. Eilerman et al. [8] studied the patellofemoral contact pressure in human cadaveric knees after harvesting the central one-third of the PT. They concluded that there were no statistically significant differences between the control and the harvested knees whether the tendon defect was closed or not. Shaffer and Tibone [21] prospectively studied PT length after ACL mid-third reconstruction. They concluded that there was no evidence that use of the PT causes or results in significantly measurable shortening, whether the defect is closed or left open. No other randomized studies to our knowledge can be found in the literature. Coupens et al. [7] followed with MRI the PT of 20 patients who underwent ACL central third PT reconstruction with defect closure after harvesting. They found a significant increase in thickness at 4, 6 and 9 months postoperatively, while at 18 months the tendon thickness was quite normal. No change was noted in width at all periods of follow-up. Burks et al. [5] studied the biomechanical properties and histology of the canine PT after removal of its central third at time 0, 3 and 6 months postoperatively. Two groups were killed at 3 and 6 months; in six dogs the tendon defect was left open and in one, closed. Their results have to be considered indicative if referred to the defect open group, even if they asserted that no differences were found in the results between leaving the tendon defect
open or not. They found that 6 months after removal of its central third the PT had a failure load reduced to 60%, stiffness to 70% and modulus to 33% of normal. There was also a significantly greater cross-sectional area of the operated tendon compared with controls, with poor organization of collagen across the entire tendon. The same group [15] studied the canine PT after removal of the medial third and found that failure load, stiffness and modulus were much less reduced than noted in the previous study when harvesting the central third. Thus, we considered that a prospective randomized study in human PT after removal of its central third for ACL reconstructions based on clinical observations, ultrasonography, CT and isokinetic testing could give more and detailed information. Evaluating the clinical data of the early post operation period (4th and 14th days), only minimal differences emerged between the two groups. R O M was strangely a little bit better in group I, but more patients in group II were able to fulfil a valid isometric contraction of quadriceps and SLR. The differences were non-existent after 3 months, as all patients had full R O M and a good quadriceps function (clinically tested). Ultrasonography after 3 months post operation showed that nearly 70% of PT in group I was thickened, while only 40% was thickened in group II. Echogenicity was diminished in 60% of PT of group I and in 40% of group II. These data are very different between the two groups, and this difference grew at CT examination after 6 months post operation. All the PT in group I were thickened and showed the presence of scar tissue not only in their central third, but also in more than a half of the medial and lateral thirds. The width of the tendons seemed, on average, 15% less than normal, but this value was calculated only in those patients who also underwent CT before the operation, namely 12 in group I and 9 in group II. Results are very different in group II, in which only 25% of patients showed a thickened PT. This thickening was, among other things, mild. The width of the tendon was normal, and scar tissue was present only in the central third. Our results with CT in group I show similar characteristics to the histological observations made by Burks et al. [5] in dogs in the above-mentioned work, in which the tendon defect was left open in most cases. However, it suggests that a massive presence of scar tissue in a tendon, especially if it is thickened twice, could mean a significant reduction in the biomechanical properties. It remains to be explained why, if the defect is closed, the tendon responds with this exuberant scar reaction. One reason could be the presence of absorbable sutures, which act as extraneous bodies, or because closure changes the normal trophic axis of the tendon, which reacts in order to restore it. However, patella height in our study as evaluated on X-rays at 6 months post operation, did not show any changes in either group, and we think that thanks to CPM and early rehabilitation, the healing process of the PT does not cause shortening. Concerning the incidence of patellar irritability, similar in both groups (32% and 36%, respectively) in our study, it is difficult to assert something about the pathogenesis. We were hoping to find a different incidence be-
17 tween the two groups, in order to have a significant clinical value that could definitively settle the e n i g m a of whether the tendon defect has to be closed or not. However, in the patients in w h o m the defect is closed, the proximal part of the defect, just below the lower pole of the patella, still remains open, and thus, the healing process (both tendinous and osseous) in that area is probably the same in both groups. The isokinetic testing revealed a lower quadriceps deficit in group II than in group I, but the difference was so slight that it is not statistically significant. W h i l e evaluating the quadriceps trophism (circumference of thigh), we f o u n d that in group II, all the patients who returned to sports did not have hypotrophy or had less than 1 cm hypotrophy. In group I, in contrast, three patients out of ten (33%) who returned to sports still presented a quadriceps hypotrophy of 2 or 3 cm. Unfortunately, this value was recorded only in the 15 patients who u n d e r w e n t isokinetic testing, and so it has less significance, but we hypothesise that closure of the defect, by altering the trophic axis of the tendon, could in some way damage the extensor m e c h a n i s m , which will have difficulty regaining its former function. This theory is also supported by the study of Linder et al. [15]. For all of these reasons we think that it is "probably" better to leave the defect open! Also, even if the knees seem stable after A C L PT reconstruction, we must not encourage an early return to vigorous sport activities, to avoid any dangerous effect on the harvested PT. It is obvious that other studies are needed to definitely settle the e n i g m a of whether the t e n d o n defect has to be closed or not.
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