Image Interpretation: There is an anechoic defect at the anterior supraspinatus insertion to the articular surface of the humerus. This defect is a partial thickness and partial width. The defect is just lateral to the biceps tendon, which appears intact. The defect is isolated to the anterior fibers of the supraspinatus tendon. There does not appear to be any bursal effusion, and no cortical surface irregularity is noted. The posterior fibers of the supraspinatus tendon in the long axis are intact.
Teaching Pearl: It is important to visualize the rotator cuff footprint where the supraspinatus tendon inserts to the articular surface of the greater tuberosity of the humeral head. Partial Articular-sided Supraspinatus Tendon Avulsion (PASTA) lesions are the most common type of partial-thickness rotator cuff tears. Note, partial-thickness, partial-width articular sided supraspinatus tendon tear and PASTA can be used interchangeably with the former being the more common terminology. In this type of pathology, the supraspinatus tendon tear appears at the attachment site (articular surface), as visualized in this case. It is important to scan in both short axis and long axis to confirm pathology and account for anisotropy. In this case, the tear was partial width and only visualized in the anterior fibers of the supraspinatus tendon.
Additionally, articular sided supraspinatus tears are often associated with a cartilage interface sign, seen as a thin hyperechoic line superficial to the hyaline articular cartilage of the humeral head. This is a sensitive but not specific sign of an articular sided tear.