Rotator cuff stability vary according to their stiffness and the direction of the force they apply upon the joint. In addition to stabilizing the glenohumeral joint and controlling humeral head translation, the rotator cuff muscles also perform multiple functions, including abduction, internal rotation, and external rotation of the shoulder. The infraspinatus and subscapularis have significant roles in scapular plane shoulder abduction (scaption), generating forces that are two to three times greater than the force produced by the supraspinatus muscle. However, the supraspinatus is more effective for general shoulder abduction because of its moment arm. The anterior portion of the supraspinatus tendon is
Rotator cuff tear hemorrhage of the tendon and bursa. Stage II involved tendinitis and fibrosis of the rotator cuff in 25- to 40-year-olds. Stage III involved tearing of the rotator cuff (partial or full thickness) and occurred in those older than 40 years. For surgical purposes, tears are also described by location, size or area, and depth. Further subclasses include the acromiohumeral distance, acromial shape, fatty infiltration or degeneration of muscles, muscle atrophy, tendon retraction, vascular proliferation, chondroid metaplasia, and calcification. Again, in surgical planning, age-related degeneration of thinning and disorientation of the collagen fibers, myxoid degeneration, and hyaline degeneration are considered. However,