Shoulder and Elbow

Shoulder Dislocation

Anatomy

The shoulder is a complex, ball-and-socket joint that rotates through a greater range of motion than any other joint in the body. The shoulder is made up of: the upper arm bone (humerus), shoulder blade (scapula), and collarbone (clavicle). The AC (acromioclavicular) joint is formed where a portion of the scapula (acromion) and the clavicle meet and are held together by ligaments that act like tethers to keep the bones in place. The ball, or head of the upper arm, fits into a shallow socket (glenoid) in the shoulder blade. The ends of these bones, where they touch, are covered with articular cartilage, a smooth substance that protects the bones and enables them to move easily. The glenoid is ringed by the labrum, a strong, fibrous cartilage that forms a gasket around the socket, adding stability and cushioning the joint.

The shoulder joint is surrounded by bands of tissue, called ligaments, to form a capsule that holds the joint together. The undersurface of the shoulder capsule is lined by the synovium, a thin membrane that produces synovial fluid to lubricate the cartilage and eliminate friction. Four tendons surround the shoulder capsule and help keep the arm bone centered in the shoulder socket. This thick tendon material, called the rotator cuff, covers the head of the humerus and attaches it to your shoulder blade. Between the rotator cuff and the bone on top of your shoulder (acromion), a lubricating sac (bursa) helps the rotator cuff tendons glide smoothly during movement.

Normally, these components work together in harmony, but when disrupted by disease or injury the result can be pain, muscle weakness and reduced function.

Description

The shoulder is the body's most mobile joint and it can turn in multiple directions. However, this advantage also makes the shoulder an easy joint to dislocate. A dislocated shoulder occurs when the head of the upper arm bone (humerous) is either partially or completely out of its socket (glenoid). Whether it is a partial dislocation (subluxation) or the shoulder is completely dislocated, the result can be pain and unsteadiness in the shoulder. If the shoulder dislocates time and again, there is shoulder instability.

Symptoms

Frequent symptoms of a dislocated shoulder include swelling, numbness, weakness and bruising. The dislocation can tear ligaments or tendons, or damage nerves. The muscles may also have spasms from the disruption, which can make the injury more painful.

Shoulder joints can dislocate forward, backward or downward, however, it is most common for the shoulder to slip forward (anterior instability) so the upper arm bone moves forward and down out of its joint. Putting the arm into a throwing position is one common cause of shoulder dislocation.

Diagnosis

Your physician will examine the shoulder and may order an X-ray or other imaging tests to help confirm your diagnosis and identify any additional problems. It is important for your doctor to know how the dislocation occurred and whether the shoulder has ever been dislocated before.

Treatment

A dislocated shoulder may pop back in on its own, or it may remain dislocated until it is put back into place. If a dislocation occurs while on the athletic field, an athletic trainer or doctor may manipulate the arm to put the ball of the upper arm bone (humerus) back into the joint socket. This process is referred to as closed reduction. If no healthcare professionals are present, it may be necessary to go to the emergency room for medical attention. Although the pain may be severe, it should stop almost immediately once the shoulder joint is back in place.

Rehabilitation

Following treatment, the shoulder will require plenty of rest to heal. Your physician may recommend that the shoulder be immobilized in a sling or other device for several weeks. Applying ice to the sore area 3 to 4 times a day can help to relieve symptoms. The proper way to ice an injury is to apply crushed ice directly to the injured area, but over a thin cloth. Ice should not be applied directly to the skin and should be applied for no more than 15 to 20 minutes at a time, waiting at least one hour between icing sessions. Chemical cold products ("blue" ice) should not be placed directly on the skin and are not as effective.

Once pain and swelling have subsided, rehabilitation exercises may be prescribed to strengthen muscles, restore range of motion and prevent dislocating the shoulder again. Rehabilitation will begin with gentle muscle toning exercises. Weight training may be added later. However, if therapy fails and repeated dislocations occur, surgery may be necessary to repair or tighten torn or stretched ligaments, particularly in young athletes. In individuals over the age of 40, rotator cuff tears frequently occur with a shoulder dislocation and these may require surgical treatment to repair. Your surgeon will tell you when you can return to work, driving and normal daily functions.