The shoulder is a ball and socket joint. The ball is large and the socket is shallow. Together they resemble a golf ball sitting on a tee. This large ball and shallow socket arrangement allows for great mobility of the shoulder joint which in turn promotes the ability to do skillful overhead motions.

The shoulder joint can become unstable in two ways. One is due to a traumatic event that forces the ball out of the socket, tearing the supporting structures called the labrum and the ligaments. These traumatic “dislocations” usually require that the ball be maneuvered back into the socket using muscle relaxing medications in an emergency room setting.

The other type of instability is more subtle and is due to gradual stretching out of the ligaments from overuse. This stretching allows the ball to partially slide out of the socket (“subluxate”) and generally causes pain or can lead to the feeling of having a “dead arm”.

Treatment of traumatic dislocations is with a special shoulder immobilizer that has been recently shown to promote healing of the injured tissues. If this is unsuccessful, surgery (either arthroscopic or open) can restore stability.

For the overuse subluxations, specialized rehabilitation is recommended with the goal of strengthening the muscles that assist keeping the ball centered in the socket. If begun in the early stages of the problem, rehab can be effective. If problems persist, surgery is the next option.