Shoulder instability occurs when the structures that surround the shoulder joint loosen and cannot maintain the ball within its shallow socket. If the joint is too loose, it may slide partially out of place, a condition known as "shoulder subluxation."
When the joint comes completely out of place, also called "shoulder dislocation", the ligaments that support the shoulder are torn. Normally, this injury does not heal tightly, making the shoulder prone to repeat dislocation and additional episodes of instability.
With shoulder instability, some activities can create sudden pain, a sense of arm deadness, or the feeling of your shoulder slipping out and back into the joint. If you experience complete dislocation, you may have severe pain along with the inability to "reset" the joint.
Some shoulder instability can be treated with rest followed by rehabilitation. However, in certain instances, the physician may recommend surgery - these include more complicated injuries, cases of recurrent instability, and first-time dislocations in younger patients who have a high risk of recurrence, further damage, or limited activity.