Impingement of the deep surface of the subscapularis tendon and the reflection pulley on the anterosuperior glenoid rim: A preliminary report

Sixteen patients underwent detailed arthroscopic evaluation; all had modera te to severe, primarily unexplained shoulder pain provoked by anterior elev ation and internal rotation, and all were nonresponsive to subacromial inje ction of local anesthetic. None of the patients had any symptoms or signs o f instability. Partial subscapularis lesions were documented in 10 of 13 pa tients who had undergone preoperative arthro-magnetic resonance imaging. At arthroscopy, an isolated lesion of the common humeral insertion of the sup erior glenohumeral and coracohumeral ligaments (a so-called pulley lesion) was found in 3 cases, a lesion associating a pulley and an articular side p artial subscapularis lesion in 10 cases, and an isolated articular side par tial subscapularis tear in 3 cases. The most painful movement, which consis ted of flexion and internal rotation, caused impingement of the involved li gamentous and/or capsular insertions in all patients. If the arm was elevat ed above 90 degrees, the zone of mechanical contact was between the long he ad of the biceps and the pulley region and superiormost aspect of the labru m; if elevation was decreased, impingement occurred between the tendinous i nsertion of the subscapularis and the anterior glenoid labrum and rim. This study suggests that in addition to the posterosuperior impingement of the supraspinatus tendon originally described by \Walch, anterosuperior impinge ment of the deep surface of the subscapularis is a form of intraarticular i mpingement responsible for painful structural disease of the shoulder.