Medical Library

Shoulder instability occurs when the shoulder moves completely out of its socket (dislocation) and requires a medical professional to “relocate it”, or to a lesser degree, when it slips out of joint but spontaneously move back in place (subluxation). Usually, the shoulder dislocates or subluxes forward (this is called an anterior dislocation). Much less often, it dislocates backward (posterior dislocation), and sometimes, it can slip out forward, backward, or downward (this is called multidirectional instability). Remember, you may have an “unstable” shoulder that has not completely dislocated.

The shoulder is most at risk for anterior dislocation when the arm is placed in an abducted and external rotated position (such as a fall on the outstretched hand or tackling a player).

An anterior dislocation is obvious because it is immediately noticed by the person right after the trauma. However, minor instability may result in a sensation that the shoulder is slipping out of place with or without pain. One might also experience pain or a sense of “apprehension” when the arm is abducted and externally rotated (ask your physical therapist about this).

A sudden dislocation is an emergency. The patient should be taken to the emergency room immediately to make sure there is no damage to the blood vessels or nerve that go to the shoulder, arm, and hand. Usually, the emergency room physician can move the arm in such a way that the dislocated shoulder reduces back into its proper place. Rarely is surgery indicated. Pain and muscle relaxant medication is often prescribed. Ice can also help reduce the pain. Physical therapy is usually started 2-3 weeks after a dislocation to strengthen the muscles that support the shoulder joint.