The rotator cuff is made up of four muscles whose tendons come together to form a covering around the head of the humerus (upper arm bone) and top of the shoulder. Together with the joint capsule, ligaments and labrum, the rotator cuff muscles are important dynamic stabilizers and movers of the shoulder joint. As the name implies, the rotator cuff functions to internally and externally rotate the shoulder and lift the arm.
Diagram of the shoulder, including the location of the rotator cuff
Rotator cuff tendonitis (inflammation) and eventual tearing occurs most commonly over a prolonged period of repetitive injury, usually with overhead activities such as throwing sports or tennis. However, the rotator cuff may be acutely injured in trauma involving heavy lifting or a fall on the arm and shoulder. Shoulder dislocation may also result in a rotator cuff tear. Symptoms of rotator cuff tendonitis or tear include pain in the front and/or down the outside of the shoulder, weakness, and stiffness.
Diagnosis of rotator cuff injury is made through careful history and physical exam. Conditions that may result in similar symptoms are a “pinched nerve” in the neck or shoulder arthritis. Rotator cuff tendonitis may be treated with rest, anti-inflammatory medication or steroid injection; usually followed by supervised physical therapy to regain shoulder motion and strength. A partial or complete tear of the rotator cuff tendon generally requires surgical repair with arthroscopy. An open surgical repair through a larger incision may be necessary for large complicated cuff tears.