Tears of the most anterior portion of the rotator cuff, the subscapularis tendon, are reported to be uncommon and rarely occur in isolation. The MR findings of subscapularis tendon tears have received little attention in radiologic publications. Accordingly, the objective of this study was to describe the MR imaging findings in the shoulders of patients with tears of the subscapularis tendon.

Preoperative MR images of nine patients with surgically confirmed rotator cuff tears that predominantly or exclusively involved the subscapularis tendon were analyzed.

In all patients, MR imaging showed the contours of the subscapularis tendon to be poorly defined and the tendon itself to be of abnormally high signal intensity on T2- or T2*-weighted images. Discontinuity and frank retraction of the tendon were evident in seven patients (78%). Thickening of the distal portion of the tendon (n = 3) and calcification (n = 1) were seen less frequently. Associated abnormalities of the biceps tendon were common, seen in seven patients (78%), five of whom had medial dislocation of the tendon. Bone and labral injuries were uncommon.

Tears of the subscapularis tendon can be identified on MR images as areas of disorganized tendon morphology and abnormal high signal intensity on T2- or T2*-weighted images. Abnormalities of the biceps tendon also are seen commonly. When subscapularis tears are recognized, the long head of the biceps tendon should be scrutinized for associated injury or malposition.