Anatomical variations in pectoralis minor muscle attachment to the coracoid process relevant to muscle transfer: A cadaveric study.

Abstract

In pectoralis minor muscle (PMiM) transfer, the PMiM tendon is typically harvested with a bone chip using a chisel from the medial surface of the coracoid process, as it is primarily composed of muscle tissue. However, variations in the insertion patterns and attachment sites of the PMiM tendon on the coracoid process have been reported, which may affect surgical techniques. This study aimed to investigate the anatomical variations in the attachment site of the PMiM tendon to the coracoid process using cadaveric shoulders. The attachment site of the PMiM tendon to the coracoid process was examined in 22 cadaver shoulders. The coracoid length and width were also measured as indicators of body size. In 11 of the 22 shoulders, the PMiM tendon was attached to the medial surface of the coracoid process. In the remaining 11 shoulders, the tendon was attached to either the superior or medial-to-superior surface, with the tendon extending toward the glenohumeral joint. The mean coracoid length and width were 42.1 ± 4.2 mm and 17.1 ± 2.1 mm, respectively, and both measurements were significantly greater in shoulders with medial surface attachments (P < 0.05). The PMiM tendon was attached to the medial surface of the coracoid process in 50 % of the examined shoulders. Shoulders with medial surface attachments exhibited significantly greater coracoid lengths compared with those with superior or medial-to-superior attachments. These anatomical insights may assist in reducing the risk of damaging the muscle-bone junction during PMiM tendon harvesting for surgical transfer.