Subscapularis Tear: Intraoperative Evaluation and Treatment

Abstract

The subscapularis represent the anterior portion of rotator cuff and it is very important to stabilize the shoulder on the coronal and on the transverse plane. Balancing the coronal and transverse plane force couple is essential in providing a stable fulcrum for glenohumeral joint motion [1]. In a cadaveric study, some authors noted that when an anterosuperior rotator cuff tear extends into the upper subscapularis, glenohumeral joint kinematics start to be altered [2]. Conversely, glenohumeral kinematics were not altered in presence of an isolated tear of the middle portion of supraspinatus tendon. The upper part of the subscapularis tendon, in fact, is the zone where the fibers of subscapularis fuse with the most anterior fibers of supraspinatus tendon forming the anterior cable. Subscapularis tears usually originate proximally in the upper band and tend to propagate distally to the lower band. An EMG study showed, however, that the lower subscapularis has significantly higher muscle activity during shoulder elevation and this reflect its greater role as a humeral head depressor and anterior stabilizer [3]. A recent clinical paper confirmed this evidence, and furthermore showed that a dysfunction of the entire subscapularis (upper and lower part) and supraspinatus was associated with the loss of active elevation and was a risk factor to develop a pseudoparalytic shoulder [4].