Shoulder Dislocation
Ross Hauser, M.D., Mario Hauser, M.S.,R.D.

Shoulder dislocation occurs when an athlete falls on an outstretched hand or when an anterior force to the shoulder occurs when the shoulder is abducted and externally rotated. This is the position of the shoulder when, for example, a person is waving to someone. Very few people dislocate their shoulder for the first time without having a significant force or injury.

There is more than one type of shoulder dislocation, but far and away the most important is the anterior dislocation, which occurs in approximately 95 percent of all cases. In this dislocation, the anterior static shoulder stabilizers, including the anterior capsule and the inferior glenohumeral ligament, are torn away from the bone. In some cases a chip of bone from the posterolateral aspect (Hill-Sachs lesion) of the humeral head (ball) or a torn rim (Bankart lesion) of the glenoid (socket) may occur. If the athlete is young there is a high likelihood that the dislocation will occur with further sports participation. Older individuals are less likely to dislocate because of less elasticity in the tissues. Exercise and rehabilitation usually follow a period of immobilization after an anterior dislocation and, if this fails to restore strength and stability to the shoulder, surgery is usually recommended.

In one definitive 10-year prospective study it was found that half of those treated with immobilization had recurrent dislocations and, of these, half had surgical treatment. This study included 247 patients with first-time dislocations. (Hovelius, L. Anterior dislocations of the shoulder in teen-agers and young adults. Journal of Bone and Joint Surgery American. 1987; 69 (3):393-9)

It demonstrates an alarming number of athletes who are unable to continue their sport without further dislocation or the need for surgery. This also does not address the percentage of athletes who do have surgery and return to their sport. In my experience, an athlete who undergoes surgery rarely is able to perform as well as before surgery.

Acromioclavicular Joint Separations
The acromioclavicular joint, or AC joint, consists of the lateral end of the clavicle, or collarbone, and a bony shelf from the scapula, called the acromion process. This joint is held together by a capsule and a number of important ligaments, which also attach to the coracoid process, a small bone projecting from the scapula (the shoulder blade) just below the AC joint.

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