Shoulder instability means the shoulder joint is too loose and it is able to slide around too much in the socket. In some cases, the unstable shoulder actually slips out of the socket and dislocates. If not treated, the instability can lead to arthritis of the shoulder joint. Treatment goals for shoulder instability are to initially alleviate pain and reduce inflammation. A rehabilitation program helps with strengthening the shoulder and positioning techniques in order to regain stability of the joint.