Shoulder Instability - Multidirectional

From Economou SG, Economou TS: Instructions for Surgery Patients.
Philadelphia, WB Saunders, 1998, p. 551.

Description
Multidirectional shoulder instability is a problem of the shoulder joint in which the upper arm (humerus) is displaced from its normal position in the center of the socket (glenoid) and the joint surfaces to no longer touch each other. With this type of instability, the humerus may move in front of (anterior), below (inferior), or behind (posterior) the glenoid. Because the shoulder has more motion than any other large joint in the body, it is the most commonly dislocated large joint. The shoulder is like a golf ball on a golf tee. A few of the many structures that provide shoulder stability include the cartilage rim (labrum), which helps provide depth to the socket; the capsule, with thickenings that are the ligaments of the shoulder; and the muscles of the rotator cuff, which surround the shoulder. To dislocate the shoulder, the rotator cuff muscles need to be stretched or torn, the capsule and ligaments need to be stretched, and often the labrum is pulled off the glenoid. Subluxation of this joint is also common in sports; this is when the ball of the humerus does not stay centered in the socket with shoulder motion and feels like it wants to slip out of place. Subluxation of the shoulder leads to overuse of the rotator cuff muscles by trying to keep the humeral head in the center of the socket causing rotator cuff symptoms. Further, fatigue of the rotator cuff muscles as the deltoid muscle contracts may push the humeral head up to the roof of the shoulder, pinching the subacromial bursa and supra-spinatus tendon (part of the rotator cuff). This type of instability tends to occur in loose-jointed (“double-jointed”) people.

Common Signs and Symptoms - Notify a physician if any of these symptoms persist:

Severe pain in the shoulder at the time of injury, although many people do not have an injury and may not have pain that is severe
Pain when using the arm overhead or carrying heavy objects with the arm at the side
Loss of shoulder function and pain when attempting to move the shoulder
Commonly, both shoulders affected
Feeling like your shoulder wants to slip out of place
Tenderness, deformity (fullness in the armpit and prominent roof of the shoulder or fullness in the back of the shoulder), and occasionally swelling
Pain with moving the shoulder, especially when reaching overhead; pain with heavy lifting; pain that awakens you at night
Loss of strength
Numbness or paralysis in the upper arm and deltoid muscle from pinching, stretching, or pressure on the blood vessels or nerves
Feeling and sound of crepitation (“crackling”) when the injured area is touched or with shoulder motion
Decreased or absent pulse at the wrist because of blood vessel damage (rare)

Treatment Considerations
After reduction (repositioning of the bones of the joint), treatment consists of ice to relieve pain. Reduction usually can be performed without surgery; surgery may rarely be necessary to restore the joint to its normal position, as well as to repair ligaments. Often patients are able to reduce the shoulder themselves. Immobilization by sling or immobilizer for 3 to 8 weeks is usually recommended to protect the joint while the ligaments heal. After immobilization, stretching and strengthening of the stiff, injured, and weakened joint and surrounding muscles (due to the immobilization and the injury) are necessary. These may be done with or without the assistance of a physical therapist or athletic trainer. Surgery is uncommonly recommended after the first dislocation to tighten the shoulder ligaments and repair the labrum. Surgery is usually reserved for those who have recurrent dislocations despite appropriate rehabilitation. This can be done arthroscopically or through a standard incision.