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Disorders (other than fractures and dislocations) > Shoulder (Gleno-Humeral) Instability What is Glenohumeral Instability? After being treated for an initial dislocation of your shoulder, you may find that it feels like it’s about to dislocate periodically. This feeling of giving-way is called glenohumeral instability or subluxation. Glenohumeral instability refers to a condition in which the humeral head in the shoulder repeatedly slips out of the joint, or seems to nearly slip out. The shoulder blade and humerus, or upper arm, form the glenohumeral joint. This is what you would normally think of as your "shoulder joint". The glenohumeral joint is a ball-and-socket joint, consisting of the head of the humerus, or upper arm, and the glenoid fossa, which is formed by a slightly hollowed portion of the end of the shoulder blade. The head of the humerus maintains very little contact with the glenoid itself during movement, however. Instead, the shoulder relies on a group of ligaments, muscles and tendons to help keep the humerus in the proper place, and to provide stability to the joint. As the arm moves in any direction, these ligaments and muscles maintain the proper position of the humeral head in the socket. During forceful motion or injury, however, these tissues can be stretched or torn, and the head can “slip out” of the socket, or dislocate. Your doctor may also use the term “subluxate,” meaning that it has only partially dislocated. Dislocations are most commonly anterior, meaning that the head of the humerus slips forward out of the joint. An injury where the arm is turned outwards and away from the body, such as a fall sideways on the arm, can cause an anterior dislocation. Very occasionally a dislocation can be posterior, where the humeral head slips backwards out of the joint. This usually occurs from a different type of injury, in which the arm is struck while is rotated inwards. Causes of Glenohumeral Instability? Unfortunately, once you’ve dislocated your shoulder, the chances are high that it will happen again, particularly if you are under age 30. That makes it all the more important that you follow your doctor’s healing and rehabilitation program carefully. In glenohumeral instability, patients are unable to keep the humeral head centered in the glenoid socket. Symptoms of Glenohumeral Instability? Patients with glenohumeral instability report that their shoulder continually slips out of joint, especially when they throw something, or possibly bump into something. Physicians should ask patients if they can voluntarily make their shoulder dislocate, which is an obvious indicator of glenohumeral instability. Your doctor will classify the instability as either acute or chronic, depending on the symptoms and how long you’ve had them. Instability is classified as chronic if it lasts for more than a few days. For some people, purposely dislocating their shoulder may be a source of amusement or entertainment. However, it only makes it more difficult to maintain stability when you need it, and can contribute to a condition where the instability cannot be resolved. Treatments of Glenohumeral Instability? Physicians will diagnose glenohumeral instability by gently moving the patient’s shoulder until it starts to slide out and cause the patient too much pain to move it any further. Chronic instability is treated first by attempting to strengthen the muscles in the shoulder, to compensate for the loose ligaments. Your doctor or a physical therapist can suggest some exercises that will isolate these muscles. While exercise will be tried first, to try to prevent further dislocations, surgery may be necessary if the shoulder cannot be stabilized sufficiently. There are many different surgical procedures to repair the instability of recurrent shoulder dislocations. Because one common cause of instability is a tear in the ligaments that attach to the socket, or glenoid, surgery is often done to repair this damage. By returning the ligaments to their original position, and then letting them heal completely, the joint can be restored to a more stable condition. This surgery is known as a Bankart repair for the specific type of tear in the ligaments, or “Bankart lesions.” The surgeon may make a small incision on the front of the shoulder, or may use an arthroscope, which is a small camera which is inserted through a much smaller incision. Surgical instruments can also be inserted through tiny incisions, and the camera used to visualize the structures while the repair is performed. After surgery and time for the repaired ligaments to heal, a rehabilitation program designed to strengthen the muscles will be started. The information provided herein is not intended to be a substitute for professional medical advice. You should not use this information to diagnose or treat a health problem or disease without consulting a licensed physician. © 2000 DynoMed.com, LLC, Indianapolis, IN |