Joint Instability

Overview

The shoulder is a ball and socket joint with a wide range of motion formed by the upper arm bone (proximal humerus) and the socket of the shoulder blade (scapula).

The ball of the upper arm bone is held firmly in place by the socket lining, cartilage rim (labrum), tendons, and ligaments.  When those stabilizing structures stretch, tear, weaken, or are otherwise injured, the ball of the humerus is able to move out of the socket more than intended, and the joint becomes unstable.  

Joint instability causes

Causes of shoulder joint instability include:

• Repeated shoulder dislocations
• The repetitive overhead strain on the joint such as throwing a baseball, swimming, volleyball, and motions required by certain occupations
• Having naturally loose joints or joints that move in more than one direction
• Youth are susceptible to joint instability until their tendons, ligaments, and bones are fully developed

Joint instability risk factors

You may be at an increased risk of shoulder joint instability if you:

• Have a history of shoulder dislocations
• Engage in repetitive motions requiring overhead use of the shoulder joint such as throwing a baseball, swimming, or as required by certain occupations
• Have naturally loose joints or joints that move in more than one direction

Youth are susceptible to joint instability until their tendons, ligaments, and bones are fully developed.

Joint instability symptoms

Symptoms of joint instability may include:

• Reoccurring shoulder dislocations
• Feeling of looseness or the joint slipping out of place
• Feeling pain, numbness, or tingling in the joint as a result of injury

Joint instability complications

Complications arising from shoulder joint instability may include:

• Repeated subluxations (partial dislocations)
• Surgical repair and subsequent surgery if unsuccessful
• Rotator cuff damage
• A decrease in range of motion
• Blood vessel and nerve damage

Joint instability prevention

Joint instability can be prevented by:

• Avoiding high risk and repetitive activities requiring overhead use of the shoulder joint
• Wearing proper protective equipment during sports
• Maintaining strength and flexibility in muscles and joints

Joint instability diagnosis

Medical professionals can usually diagnose a dislocated shoulder by a visual and physical examination.  X-rays may be used to confirm your diagnosis.

Joint instability treatment

Non-trauma related instability is treated by strengthening the rotator cuff and stabilization muscles. Exercises to improve shoulder movements may also be recommended.

Trauma-related instability is treated first by reducing pain and swelling with ice and anti-inflammatory medications.  Stabilizing the joint may require temporary use of a sling followed by a program of strengthening and coordination exercises.

Surgery to repair and strengthen tendons, ligaments, or muscles is recommended in some cases.

When to seek care

Seek care if you experience swelling, bruising, severe pain, deformity, or any other symptoms listed above as a result of physical trauma to the joint or if you have chronic symptoms like shoulder laxity.

Next Steps

Your doctor will assess your symptoms and provide treatment accordingly.