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:
- Subluxation—The humeral head moves partially out of the shoulder socket.
- Dislocation—The humeral head moves completely out of the socket.
- Anterior—The humeral head moves toward the front.
- Posterior—The humeral head moves toward the back.
- Inferior—The humeral head drops downward.
- Multidirectional—The humeral head moves toward difference places.
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Factors that may increase your chance of shoulder instability include:
- Trauma, such as a fall with an outstretched arm or a direct blow to the shoulder
- Previous shoulder dislocation
- Athletic activity, especially:
- Any collision or contact sport
- Swimming, especially backstroke or butterfly
Congenital collagen disorders, such as:
- Marfan syndrome—a connective tissue condition
- Ehlers-Danlos syndrome—a condition marked by loose joints
- Family members with shoulder instability
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:
- MRI scan
- CT scan
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:
- Rest—Avoid activities that produce pain or stress the joint.
- Ice—This helps to control pain and inflammation, especially after exercise.
- Medication—Nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, may be given to manage pain.
Rehabilitation—This can last several months and may include:
- Physical therapy to strengthen the muscles that control the shoulder joint, particularly the internal rotators of the shoulder
- Specific exercises for certain sports or job activities
- Learning how to modify activities to prevent reinjury
- Surgery—Many different procedures may be used to correct shoulder instability. The goal is to fix the cause. An arthroscopic or an open technique may be used. After surgery, the arm is kept from moving for 3 to 6 weeks, depending on the procedure.
Guidelines to help protect the shoulder from injury include:
- Doing regular exercises to strengthen the supporting muscles
- Using proper athletic training methods
- Increasing the duration or intensity of your exercises gradually
- Modifying activities to prevent excessive external rotation and overhead motions of the shoulder
This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.
Edits to original content made by Denver Health.
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