by Debra Wood, RN
Shoulder instability occurs when the upper-end of the arm bone, known as the humerus, slides partially or completely out of the shoulder socket.
The disorder is classified by how much the humerus moves and the direction of the movement:
Shoulder instability often results from injury.
Risk Factors TOP
Factors that may increase your chance of shoulder instability include:
Symptoms may come on suddenly or develop over time. Shoulder instability may cause:
You will be asked about your symptoms and medical history. A physical exam will be done. 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.
Imaging tests evaluate your shoulder and surrounding structures. These may include:
Arthroscopy is done with an instrument with a long tube and miniature camera on the end. Repairs or corrections can be made while the doctor evaluates the shoulder joint.
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:
Family Doctor—American Academy of Family Physicians
Ortho Info—American Academy of Orthopaedic Surgeons
Canadian Orthopaedic Association
Canadian Orthopaedic Foundation
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Recurrent subluxation of shoulder. EBSCO DynaMed website. Available at:
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Updated August 21, 2014. Accessed September 29, 2014.
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Last reviewed August 2014 by John C. Keel, MD; Michael Woods, MD
Last Updated: 11/21/2013
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