Shoulder instability is a condition in which the upper-end of the humerus (the upper arm bone) slides partially or completely out of the shoulder socket.
Normally, the head of the humerus, moves within the confines of the shoulder socket. Instability occurs when the head slips outside its normal position. The humeral head may move in one or more directions. The disorder is classified by how much this bone moves and by the direction it moves:
Shoulder instability often results from an initial acute injury producing a dislocation that, even with healing, leads to stretching of the shoulder capsule and ligaments. This type of injury could be due to a fall, a direct hit, or force applied to the outstretched arm. More rarely, shoulder instability develops slowly without any history of previous injury. In some cases, the shoulder may slip out of place at predictable times, such as when lifting a suitcase or even when shaving.
A risk factor is something that increases your chance of getting a disease or condition. Risk factors for shoulder instability include:
Symptoms may come on suddenly or develop over time. Symptoms may include:
The doctor will ask about your symptoms and medical history, and perform a physical exam. Special attention will be given to your shoulders. Your doctor will determine your range of motion and try to move the humeral head within the socket.
Tests may include:
Therapy will depend on the extent of the injury, the cause, and other factors. Treatment may include:
Guidelines to help protect the shoulder from injury include:
RESOURCES:
American Academy of Family Physicians
http://familydoctor.org
American Academy of Orthopaedic Surgeons
http://www.aaos.org
CANADIAN RESOURCES:
Canadian Orthopaedic Association
http://www.coa-aco.org/
Canadian Orthopaedic Foundation
http://www.canorth.org/
References:
Behrman RE, Kliegman R, Jenson HB. Nelson Textbook of Pediatrics . 16th ed. Philadelphia, PA: WB Saunders Co; 2000.
Canale ST. Campbell's Operative Orthopaedics . 9th ed. Philadelphia, PA: Mosby Inc; 1998.
Conservative management of shoulder injuries. Orthopaedic Clinics of North America . April 2000.
Luime JJ, Verhagen AP, Miedema HS, et al. Does this patient have an instability of the shoulder or a labrum lesion? JAMA . 2004;292:1989-1999.
Mahaffey BL. Smith PA. Shoulder instability in young athletes. Am Fam Physician . 1999;59:2773.
Mulley AG and AH Goroll. Primary Care Medicine: Office Evaluation and Management of the Adult Patient. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2000.
Rockwood CA, Bucholz RW, Heckman JD, et al. Rockwood and Green's Fractures in Adults . 4th ed. Philadelphia, PA: Lippincott-Raven Publishers; 1996.
Ruddy S, Harris ED Jr, Sledge CB. Kelley's Textbook of Rheumatology . 6th ed. Philadelphia, PA: WB Saunders Co; 2001.
Last reviewed November 2008 by John C. Keel, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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