The biomechanical significance of the subscapularis tendon includes contributions to anterior stability, providing strength in internal rotation and maintaining a balanced force couple in the transverse plane of the glenohumeral joint. Subscapularis muscle–tendon unit dysfunction can produce significant anterior shoulder pain and weakness in motion. Subscapularis tendon tears can occur from overuse or chronic attenuation secondary to age, but are more likely to result from traumatic events such as falls and/or shoulder dislocation. Satisfactory results have been reported after open or arthroscopic surgical repairs of acute tears of the subscapularis tendon. repair of chronic tears has not produced such positive results. This poses a surgical challenge as subscapularis tendon tears are often missed early in the course of treatment because patients lack the classic rotator cuff symptoms. Additionally, diagnosis may be delayed as preoperative magnetic resonance evaluation of subscapularis has low sensitivity. Such degenerative subscapularis tears are usually found in patients older than 40 years of age and may also be accompanied by supraspinatus tears. If atrophy, fatty in ltration or considerable retraction is present, direct repair is especially prone to failure and the poor quality of the rotator cuff in these ruptures often does not allow for direct tendon-to-bone reconstruction.

First described in 1997 by Wirth and rockwood, the transfer of the pectoralis major tendon has been described as a salvage procedure in the treatment of irreparable subscapularis tears. Subsequent reported outcomes have been few and involved small series with variable results. Theoretical advantages of pectoralis major transfer procedure have been reported. Biomechanically, pectoralis major transfer partially restores the function of the subscapularis by recreating the anterior force couple and subsequently exerts an internal rotation centering force on the glenohumeral joint. As demonstrated by Burkhart, the improved balance in the force coupling plane is critical in providing a balanced fulcrum and allows the deltoid to effectively contribute to shoulder elevation. Furthermore, because the function of the pectoralis and subscapularis tendons is similar, biofeedback programs and retraining are minimized in the rehabilitation process.

The purpose of this study was to systematically review the literature and consolidate the existing evidence on the outcomes of pectoralis major transfers for the treatment of irreparable subscapularis tears. Three speci c aims were to:

  1. evaluate functional outcomes, strength, pain relief and range of motion after pectoralis major tendon transfer for irreparable subscapularis cuff tears.
  2. Appraise predictive factors which lead to a successful outcome.
  3. Assess the complications following this procedure.

The hypothesis was that patients would have improvement in shoulder pain and function after undergoing transfer of pectoralis major for irreparable subscapularis tears.

Full Article: Pectoralis Major Transfer for Treatment of Irreparable Subscapularis Tear: A Systematic Review