The most flexible joint in the entire human body, our shoulder joint is formed by the union of the humerus, the scapula (or shoulder blade), and the clavicle (or collarbone). Commonly thought of as a single joint, the shoulder is actually made up of two separate joints - the glenohumeral and acromioclavicular joints. These two joints work together to allow the arm both to circumduct in a large circle and to rotate around its axis at the shoulder.
The glenohumeral joint is a ball-and-socket joint formed between the articulation of the rounded head of the humerus (the upper arm bone) and the cup-like depression of the scapula, called the glenoid fossa.
A partial dislocation (subluxation) means the head of the upper arm bone (humerus) is partially out of the socket (glenoid). A complete dislocation means it is all the way out of the socket. Both partial and complete dislocation cause pain and unsteadiness in the shoulder. In anterior dislocation the humeral head has been moved to a position in front of the joint. Posterior dislocations are those in which the humeral head has moved backward toward the shoulder blade. Other rare types of dislocations include luxatio erecta, an inferior dislocation below the joint, and intrathoracic, in which the humeral head gets stuck between the ribs.
Dislocations in younger people tend to arise from trauma and are often associated with sports or falls. Older patients are prone to dislocations because of gradual weakening of the ligaments and cartilage that supports the shoulder. Even in these cases, however, there still needs to be some force applied to the shoulder joint to make it dislocate. Anterior dislocations often occur when the arm is held over the head with the elbow bent, and a force is applied that pushes the elbow backward and levers the humeral head out of the glenoid fossa.
Sometimes dislocation may tear ligaments or tendons in the shoulder or damage nerves. Thr most common symptoms to look for include:
The doctor will place the ball of the upper arm bone (humerus) back into the joint socket. This process is called closed reduction. Severe pain stops almost immediately once the shoulder joint is back in place. Significant damage occurs to the joint with a shoulder dislocation. The labrum and joint capsule have to tear, and there may be associated injuries to the rotator cuff. These are the structures that lend stability to the shoulder joint, and since they are injured, the shoulder is at great risk to dislocate again. A sling or shoulder immobilizer may be used as a reminder not to use the arm and allow the muscles that surround the joint to relax and not have to support the bones against gravity. The length of time a sling is worn depends upon the individual patient. A balance must be reached between immobilizing the shoulder to prevent recurrent dislocation and losing range of motion if the shoulder has been kept still for too long.
Physical Therapy- After the pain and swelling go down rehabilitation exercises should be started. These help restore the shoulder's range of motion and strengthen the muscles. Rehabilitation may also help prevent dislocating the shoulder again in the future.
If therapy and bracing fail, surgery may be needed to repair or tighten the torn or stretched ligaments that help hold the joint in place, particularly in young athletes.