Incomplete tears of the subscapularis tendon associated with tears of the supraspinatus tendon: cadaveric and clinical studies.

This study was undertaken to evaluate incomplete tears of the subscapularis tendon that occur in conjunction with small or medium-sized tears of the supraspinatus tendon. Fifty-two shoulders were examined in 26 embalmed cadavers. The average age at the time of death was 76.3 years. Rotator cuff tears were observed in 32 (61.5%) shoulders. Six (11.5%) shoulders had massive rotator cuff tears and were excluded from the study, leaving 46 shoulders for study. Twenty shoulders had a tear of the supraspinatus tendon, and 17 had a tear of the subscapularis tendon. All tears of the subscapularis tendon were articular-side incomplete tears. On histologic examination most pathologic changes of the subscapularis tendon were observed on the articular side of the upper portion. Lesions of the long head of the biceps brachii were identified in 14 (30.4%) shoulders. A statistically significant correlation was found between tears of the subscapularis tendon and the presence of lesions of the long head of the biceps brachii (P=.0014). In addition, the results of preoperative magnetic resonance imaging of 15 patients (average age, 62.9 years) with a surgically confirmed diagnosis of incomplete tears of the subscapularis tendon in conjunction with tears of the supraspinatus tendon were also evaluated. Incomplete tears of the subscapularis tendon could be identified on magnetic resonance imaging as an area of high signal intensity on axial T2-weighted images in all 15 shoulders studied.