The supraspinatus, infraspinatus, teres minor and subscapuĺaris muscles form a musculotendinous rotator cuff that provides dynamic stability to the shoulder joint. Symptoms of rotator cuff injury include limitation of motion, weakness and pain that often radiates down the upper arm and is present at night. Examination may reveal deltoid and rotator cuff atrophy, tenderness, limited passive range of motion and weakness on abduction and external rotation. Radiographs may show degenerative changes of the acromion or acromioclavicular joint, cysts, sclerosis and spurs of the greater tuberosity, and calcific deposits within the supraspinatus tendon. In most patients with subacromial impingement, conservative management, including physical therapy, nonsteroidal anti-inflammatory drugs and subacromial injections, is successful. Failure of conservative therapy after six to 12 weeks merits further evaluation with magnetic resonance imaging or arthrography, and consideration of surgery.