[Transfer of the clavicular portion of the pectoralis major muscle in the treatment of irreparable tears of the subscapularis muscle].

PURPOSE OF THE STUDY: Old tears of the subscapular muscle situated in the glenoid area are not accessible to direct repair and require locoregional muscle plasty. The clavicular portion of the pectoralis major can be used for reconstruction. The purpose of this study was to describe the operative technique and examine short-term outcome.
MATERIAL AND METHODS: Five patients, mean age 54 years (45-71 years) with an irreparable tear of the subscapularis in the glenoid area with fatty degeneration greater than grade two in the Goutallier classification were treated. Four had had previous surgery for acromioplasty associated with rotator cuff repair in two or implantation of a humeral prosthesis in one. The preoperative Constant score was 27.5 (mean, range=8.5-54) due to invalidating pain, limited active mobility and reduced muscle force. Gerber's lift-off test was positive for those patients for whom it could be performed. Plain x-rays evidenced anterior subdislocation of the humeral head in one case. Subscapular reconstruction was achieved using the entire clavicular portion of the pectoralis major which was dissected and sectioned at its distal insertion on the humerus then reinserted by transosseous suture onto the lesser tuberosity. The rehabilitation program started with active and passive mobility against gravity within a few days of surgery using biofeedback contraction of the muscle flap then active contractions two months postoperatively. Patients were reviewed at a mean 19 months (6-42 months) for clinical and radiological assessment.
RESULTS: Four patients had a painless shoulder with a negative lift-off test. The gain in active mobility was predominantly achieved with anterior elevation and abduction. Muscle force was weak leading to a low overall Constant score at revision (mean=50, range=30-63). Radiographically, the humeral head was centered exactly as on the preoperative films. There were no cases with a new anterior subdislocation nor an aggravation of a former subdislocation. Functional outcome was better in cases with a unique tear of the subscapularis. DISCUSSION AND
CONCLUSION: Open surgery is used for primary repair of recent tears of the subscapularis. This technique gives 80 p. 100 good and very good results. In case of symptomatic acromioclavicular osteoarthtisis, better long-term results can be obtained by using a tendodesis of the long biceps and resecting the lateral centimeter of the clavicle. In case of irreparable tears in the glenoid area, reconstruction by transfer of the clavicular portion of the pectoralis major can produce a stable painless shoulder with improved active moblity and normal clinical tests. This method provides anterior stability of the glenohumeral articulation and prevents any anterior subdislocation of the humeral head, thus protecting the joint from secondary degeneration.