ANATOMOCLINICAL EFFECT OF SUB-SCAPULAR MU SCLE VERTICAL SECTION IN LATARJET PROCEDURE

Material and methods From October Ist, 1990, to June 30th, 1991, 40 pa tients were operated according to Latarjet for chronic anterior should er instability. A vertical section of the subscapular muscle was perfo rmed. Except for one female patient, all of them practiced sports. Pre operative delay between first dislocation and surgery averaged 59 mont hs. Postoperative rehabilitation was aimed at external rotation, recov ery began 48 hours after surgery, without specific indications as far as internal rotation was concerned. Sports activity was resumed 90 day s after surgery. 38 were reviewed after 4 years. Clinical review was m ade according to Constant's score and by measuring strength, and ampli tude of internal rotation. Radiological assessment of the shoulders wa s made with standard x-rays and CT. Results For global results, we not ed absence of recurrence, a weighted Constant score of 88 per cent, 87 per cent of patients satisfied or very satisfied, 55 per cent of the osteoplastic ridge were on level, 16 per cent were retracted, and 29 p er cent overlapped, 19 per cent non union or ridge lysis, 21 per cent glenohumeral osteophytosis. As far as clinical results are concerned, no significant difference was noted associated to osteoplastic ridge p osition. Internal rotation was assessed by measuring the distance hand to back (lift-off test). On the operated side it averaged 6 cm (0-18 cm), on the other side 13 cm (2-21 cm). The difference between each si de was statistically very significant (p = 0.0001). Strength in intern al rotation on the operated side averaged 3 kg (0-8 kg), on the other side, 6 kg (2-10 kg). The difference between each side was statistical ly very significant (p < 0.0001). CT was carried out on thickness and degeneration of the subscapular muscle (n = 29). Thickness of the subs capular muscle (operated side) averaged 10.5 (5-17 mm) after surgery, and 14.6 mm before surgery. It was thimer than on the contralateral sh oulder 21 mm (10-33 mm). In both cases (shoulder before and after surg ery, operated and contralateral shoulder), the difference was statisti cally significant. Degeneration of the subscapular muscle showed 4 sta ge 0, 13 stage 1, 5 stage 2, 6 stage 3, and 1 stage 4. A non statistic al correlation was noted, between muscle degeneration and functional r esult, strenght in internal rotation, distance hand to back. Discussio n This series confirms efficiency and low morbidity of Latarjet proced ure. Nevertheless, assessment of the subscapular muscle shows that 50 per cent of its strength and 50 per cent of its thickness were lost, 4 years after surgery. A significant degeneration (stages 2.3.4) was fo und in 41 per cent of the patients. This limitation is related to the trans-subscapular approach and to the absence of internal rotation pos toperative rehabilitation. Conclusion A randomized study comparing the vertical trans-subscapular approach to the horizontal trans-subscapul ar one would determine the better procedure.