Atraumatic loose shoulder: the treatment by pectoralis major muscle transfer

From 1975, 40 shoulders of 34 patients with a loose shoulder were operated on by pectoralis major transfer. The insertions of the clavicular and sternal portions were transferred to the inferior angle of the scapula to bring the glenoid cavity upwards. The follow-up period was 5.3 years on average, and complaints of dullness of the shoulder, feeling of subluxation and dullness of the arm had decreased. However, complaints of dullness of the shoulder girdle had increased at follow-up. The inferior instability had improved in all but four shoulders because this method brings the glenoid cavity upwards and the changes of the upward rotating angle of the scapula were confirmed by roentgenographic investigations. The study of the tracking movement pointed out that this method did not affect the motion of the shoulder, and the high activity of the transferred pectoralis major muscle during the movement was thought to play an important role in reducing inferior instability. This method is most recommended for a patient who has multidirectional instability and can subluxate the head antero-inferiorly by the pectoralis major muscle, but it is not recommended for athletes as the power of the shoulder adductor is reduced to some extent after surgery.