The shoulder joint, or glenohumeral joint, is kept in place and supported by muscles, tendons, ligaments and cartilage. The shallow socket of this joint allows for great range of motion, arm rotation and the ability to lift it above the head. This wide range of movement makes the shoulder more susceptible to damage. When any structures of the shoulder are damaged, shoulder dislocation and instability can result.
Nearly 95 percent of all shoulder dislocations are in the anterior direction, meaning that the ball of the shoulder pops out in a forward direction. Dislocations are more often seen in men, and half of all dislocations occur in those ages 15 to 29. People who experience a shoulder dislocation have a higher risk of suffering a repeat dislocation, and for chronic shoulder instability.
Causes of Shoulder Dislocation and Instability
Severe injury or direct trauma is most often the cause of an initial shoulder dislocation. Often, this injury is the result of a fall, but sports and recreational activities are also responsible for a large percentage of shoulder dislocations and instability.
In some cases, dislocation can occur without a traumatic injury or history of injury, as some people have inherent looseness in their joints that makes it more likely for them to become unstable and slip out of place. Voluntary shoulder dislocation and instability can occur in people who are able to control the joint or who experience the shoulder popping out only when the joint is moved in a particular way, such as when the arm is raised above the head.
Shoulder Dislocation and Instability Diagnosis
Diagnosing shoulder dislocation or instability begins with a medical history and physical examination. The doctor will look at the arm and shoulder positions to determine the dislocation’s direction and the scope of pain and instability. Before the joint is put back into place, an X-ray will be taken to confirm the dislocation and to look for fractures that could cause additional damage. If the shoulder injury is complicated, a CT scan or MRI may be ordered to check for damage to the muscles, cartilage and other soft tissues.
Treatments for Shoulder Dislocation and Instability
As soon as possible after a dislocation and after X-rays are taken, the shoulder is put back into place. Anesthesia may not be necessary for people who have had previous dislocations or for partial dislocations, but nitrous oxide or sedation may be used to relieve pain during the procedure.
Shoulder instability is usually treated through activity modification, physical therapy exercises and nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin and ibuprofen. Surgery may be advised if torn or stretched ligaments or other damage is responsible for the instability, or if the joint is still unstable after trying nonsurgical treatment options. After surgery, a sling is worn to immobilize the shoulder, and rehabilitation may be considered.