The subscapularis footprint: an anatomic study of the subscapularis tendon insertion.

PURPOSE Arthroscopic repair of the subscapularis tendon has become more prevalent in recent years. Tears of the subscapularis insertion can be measured arthroscopically when the size of the average subscapularis tendon insertion is known. This anatomic study was performed to measure the dimensions and describe the anatomy of the subscapularis footprint. METHODS A total of 6 male and 6 female shoulders were dissected down to the insertion of the subscapularis tendon. The insertion was demarcated, the tendon was detached, and the dimensions of the insertion site were measured. RESULTS The footprint is the insertion of the subscapularis tendon onto the lesser tubercle. The shape of the footprint was characterized as resembling a human ear. The insertion is broad proximally and tapered distally and has a straight medial border that is almost parallel to the longitudinal axis of the humerus. The total average cephalocaudal height of the footprint was 25.8 mm (+/-3.2 mm). The total average width was 18.1 mm (+/-1.6 mm). Average male cephalocaudal height was 26.7 mm (range, 22 to 32 mm), and width was 18.3 mm (range, 16 to 21 mm). Average female cephalocaudal height was 24.8 mm (range, 22 to 29 mm), and width was 17.8 mm (range, 15 to 19 mm). Although the male footprint was slightly larger than the female footprint, differences were not statistically significant (P = .18 and .31 for height and width, respectively). CONCLUSIONS An anatomic study was performed to determine the size of the footprint of the subscapularis tendon. We found that the average cephalocaudal height of the footprint was 25.8 mm, and the average width was 18.1 mm. CLINICAL RELEVANCE Subscapularis tears are now more frequently addressed arthroscopically. This anatomic study was performed to characterize the anatomy of the subscapularis footprint so that the surgeon can achieve a more anatomic repair.