Rotator cuff tear factors contribute to degenerative, or chronic, rotator cuff tears of which repetitive stress is the most significant. This stress consists of repeating the same shoulder motions frequently, such as overhead throwing, rowing, and weightlifting. Many jobs that require frequent shoulder movement such as lifting and overhead movements also contribute. Another factor in older populations is impairment of blood supply. With age, circulation to the rotator cuff tendons decreases, impairing natural ability to repair, ultimately leading to, or contributing to, tears. The final common factor is impingement syndrome, the most common non-sports related injury and which occurs when the tendons of
Glenohumeral ligaments capsule is strengthened in front by two bands derived from the tendons of the Pectoralis major and Teres major respectively. During abduction of the arm the middle and inferior ligaments become taut while the superior ligament relaxes. The radius of curvature of the head of the humerus is greater superiorly than inferiorly, which further stretches these ligaments so that they keep the articular surfaces of the joint in their close-packed position. During abduction the greater tubercle of the humerus comes in contact with the upper margin of the glenoid cavity, which limits maximum abduction. By rotating the humerus laterally, this