(See also Overview of Sports Injuries.)
The shoulders are ball-and-socket joints that allow the arms to have inward and outward rotation as well as forward, backward, and sideways movement (see Shoulder Anatomy). The shoulder tends to be unstable. It has been likened to a golf ball sitting on a tee because the socket (glenoid bone) is very shallow and small compared to the size of the ball (humeral head). To enhance stability, the socket is deepened by the labrum, a rubbery material attached around the lip of the glenoid bone. The labrum can tear during athletic activities, especially during throwing sports, or as a result of falling and landing on an outstretched arm.
When the labrum tears, the athlete feels pain deep in the shoulder during movement, for example, when pitching a baseball. This discomfort may be accompanied by a painful clicking or clunking sensation and a feeling of catching in the shoulder.
Magnetic resonance imaging (MRI) may be necessary to make the diagnosis.
Physical therapy is the usual initial treatment. If symptoms do not resolve, surgical repair is usually needed.