The most mobile joint in the body is the shoulder. Chronic shoulder instability is typically the result of frequent shoulder dislocations, when the upper arm bone (humerus) is forced or slides from the shoulder socket.
Your shoulder is made up of three bones: your upper arm bone (humerus), your shoulder blade (scapula), and your collarbone (clavicle). The head of the upper arm bone (glenoid) fits into a rounded socket. The rotator cuff is a combination of muscles and tendons that attach the glenoid to the shoulder blade. Finally, the biceps tendon is a muscle in front of the upper arm with two tendons that attach the bones to the shoulder socket.
Causes of chronic shoulder instability
Chronic shoulder instability can occur in people who tend to have laxity in their ligaments. Repeated overhead motion from activities such as swimming, tennis, and volleyball can weaken shoulder ligaments over time, leading to instablity. Certain occupations that require overhead motions, such as painting, can also cause chronic shoulder instability.
Symptoms of chronic shoulder instability
- Repeated shoulder dislocations or the shoulder “giving out”
- The sensation that the shoulder is loose, is hanging, or slips in and out of the joint
Diagnosis and treatment for chronic shoulder instability
Your physician may order an X-ray to determine the shoulder’s placement and an MRI to identify any injuries to the tendons and ligaments around the shoulder joint. Surgery is usually necessary to repair stretched or torn ligaments in order to keep the shoulder in place.