The rotator cuff helps to lift and rotate the arm and to stabilize the ball of the shoulder within the joint. The rotator cuff is made up of four muscles and their tendons. These combine to form a "cuff" over the upper end of the arm (head of the humerus). The four muscles of the cuff are attached to the scapula on the back through a single tendon unit. The unit is attached on the side and front of the shoulder on the greater tuberosity of the humerus.
The rotator cuff can be torn from a single traumatic injury. Patients often report recurrent shoulder pain for several months and a specific injury that triggered the onset of the pain. A cuff tear may also happen at the same time as another injury to the shoulder, such as a fracture or dislocation. Most tears, however, are the result of overuse of these muscles and tendons over a period of years. People who are especially at risk for overuse are those who engage in repetitive overhead motions. These include participants in sports such as baseball, tennis, weight lifting, and rowing. Rotator cuff tears are most common in people who are over the age of 40. Younger people tend to have rotator cuff tears following acute trauma or repetitive overhead work or sports activity.
Some of the signs of a rotator cuff tear include: atrophy or thinning of the muscles about the shoulder, pain when lifting the arm, pain when lowering the arm from a fully raised position, weakness when lifting or rotating the arm, and more.