Outcome of Pectoralis Major Transfer for the Treatment of Irreparable Subscapularis Tears

BACKGROUND: Chronic tears of the subscapularis tendon with or without associated tears of the supraspinatus and infraspinatus tendons may lead to pain and dysfunction of the shoulder. If conservative treatment fails and repair of the musculotendinous unit is impossible, transfer of the pectoralis major tendon can be attempted to substitute for lost subscapularis function. METHODS: Twenty-eight patients underwent a total of thirty consecutive pectoralis major transfers at an average age of fifty-three years. There were twelve isolated subscapularis tears and eighteen subscapularis tears associated with a tear of the supraspinatus or the supraspinatus and infraspinatus. All patients were examined clinically and with standard radiographs. RESULTS: The mean relative Constant score increased from 47% preoperatively to 70% at an average of thirty-two months postoperatively (p < 0.0001). The mean Constant scores for pain (p = 0.0009) and activities of daily living (p < 0.0001), the range of forward flexion (p < 0.05), and abduction strength (p = 0.001) also improved. Thirteen patients (14 shoulders) were very satisfied, ten patients (eleven shoulders) were satisfied, two patients (two shoulders) were disappointed, and three patients (three shoulders) were dissatisfied with the result. The average subjective shoulder value increased from 23% preoperatively to 55% postoperatively (p = 0.0009). In patients with a massive tear, the outcome was less favorable when the torn supraspinatus tendon was irreparable, as determined preoperatively or intraoperatively, than when it was reparable (average relative Constant scores, 49% and 79%, respectively; p = 0.002). CONCLUSIONS: Pectoralis major transfer results in improvement for patients with an irreparable subscapularis tear with or without an associated reparable supraspinatus tear. If an irreparable subscapularis tear is associated with an irreparable supraspinatus tear, the results are less favorable, and pectoralis major transfer may not be warranted.