Since the shoulder is one of the most mobile joints in the body, it is also the joint most commonly dislocated. Dislocations can either be complete (totally out of the socket) or partial which are referred to as a subluxation (partially out of socket).
Individuals under the age of 20 may have as high as a 90% re-dislocation rate because cartilage is usually torn when they dislocate. This cartilage is called the labrum and although it may heal on its own, it usually does not heal in the correct position. Since it is one of the stabilizers of the shoulder, and is no longer in the correct position to help hold the shoulder in the socket, the shoulder can now move out of the socket if the arm gets in the wrong position.
The re-dislocation rate for those over 40 is as low as 20%. This is because when they dislocate, they usually do not tear the cartilage but stretch the capsule of the shoulder instead, which can heal without surgery
These injuries normally occur from trauma, but can occur with relatively little force in individuals whose ligaments are loose. The most common dislocation is one that causes the humeral head (the ball of the joint) to dislocate anteriorly and inferiorly. This occurs with the arm out to the side and rotated back.
- Initially, severe pain until joint is reduced
- Loss of normal contour of shoulder
- If anterior dislocation, may have large bump toward chest area
- Unable to lift or rotate arm without pain
- Numbness in hand and arm, usually resolves after reduction
- After the reduction shoulder may feel loose or unstable
- Weakness if rotator cuff is torn or stretched
Initially the shoulder is reduced, usually in the emergency room. Medicine is given to relax muscle spasms and help with pain. Care after the relocation includes an examination and most likely x-rays or an MRI to determine the extent of the injury to your shoulder. You and your physician will then decide upon further care together, which may consist of a sling for several weeks and physical therapy vs. surgery to repair the cartilage.