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Shoulder Dislocation and Rehabilitation Shoulder dislocations account for up to fifty percent of all dislocations the extreme range of motion in the normal shoulder creates an inherent instability in the joint, which is thus susceptible to dislocation. Most commonly there will be an anterior dislocation. In some cases the athlete will present with a posterior dislocation perhaps ever an inferior dislocation, which are extremely rare. When an athlete dislocates his or her shoulder there is a 90 percent chance of this recurring. An anterior gleno humeral dislocation is what I will focus upon. Structurally the shoulder is an unstable joint that relies on a large network of muscles to provide stability without restricting mobility. Functional stability is almost completely dependent upon the synergism of the ligaments and musculotendinous units. The shoulder is very unstable from a bony standpoint. The only true attachment to the thorax is the junction of the clavicle with the sternum. There are three main bone structure in the shoulder the clavicle, scapula, and humerus. These bones together make up for six joints or articulations. The gleno-humeral joint is a shallow ball and socket joint that is formed by the articulation of the humeral head and the shallow glenoid fossa of the scapula. The glenoid fossa is only two thirds the size of the humeral head, and the two are only minimally held together with ligaments. The fossa is made deeper and more stable due to the glenoid labrum, a ring of fibrocartilage that surrounds the glenoid fossa. The ligament structures; muscles, and the capsule around the gleno humeral joint provide further stability. Three gleno humeral ligaments that form a Z-shape along the anterior surface of the joint provide anterior stability. These are actually heavy bands that blend with the capsule of the shoulder. Further support to the gleno humeral joint is provided anterior by the sub scapulars, superiorly by the acromion process, coracoacromial ligament and the supraspinatus, and posterior by the infraspinatus and teresminor. There is little support inferiorly to the shoulder, thus the high incidence of inferior shoulder dislocations. Movements at the gleno humeral joint include shoulder flexion, extension, shoulder internal and external rotation, shoulder abduction and adduction, horizontal abduction and horizontal adduction.
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