Shoulder Dislocations

A shoulder dislocation is an injury that occurs when the top of the arm bone (humerus) loses contact with the socket of the shoulder blade (scapula).The joint between the humerus and scapula, also called the glenohumeral joint, is a ball-and-socket joint--the ball is on the top of the humerus, and this fits into a socket of the shoulder blade called the glenoid. This joint is incredible because it allows us to move our shoulder though an amazing arc of motion--no joint in the body allows more motion than the glenohumeral joint. Unfortunately, by allowing this wide range of motion, the shoulder is not as stable as other joints. Because of this, shoulder dislocations are not uncommon injuries.

What happens?
A shoulder dislocation generally occurs after an injury such as a fall or a sports-related injury. About 95% of the time, when the shoulder dislocates, the top of the humerus is sitting in front of the shoulder blade--an anterior dislocation. In less than 5% of cases, the top of the humerus is behind the shoulder blade--a posterior dislocation. Posterior dislocations are unusual, and seen after injuries such as electrocution or after a seizure.

Symptoms
Patients with a shoulder dislocation are usually in significant pain. They know something is wrong, but may not know they have sustained a shoulder dislocation. Symptoms of shoulder dislocation include:

o Shoulder pain

o Arm held at the side, usually slightly away from the body with the forearm turned outward

o Loss of the normal rounded contour of the deltoid muscle

How is the diagnosis of a shoulder dislocation made?
Diagnosis of a shoulder dislocation is usually quite apparent just by talking to a patient and examining their joint. Patients must be examined to determine if there is any nerve or blood vessel damage. This should be done prior to reduction (repositioning) of the shoulder dislocation. X-rays should be obtained to check for any fracture around the joint, and to determine the pattern of the shoulder dislocation.



Treatment
How is a shoulder dislocation reduced?
There are several methods to reduce the shoulder dislocation into its normal position. If the patient is in the emergency room, the patient will receive anesthesia for the procedure. The two most commonly used types of anesthesia include:

* Intravenous (IV) Sedation
Most commonly, patients with a shoulder dislocation are given IV anesthesia. This both alleviates pain, and makes the patient unconscious for a few minutes. During that time, the physician can manipulate the shoulder dislocation back into position.

* Local Injection
Injection of Novocaine into the joint can provide ample anesthesia to perform a reduction of a shoulder dislocation. Recent studies have shown this type of anesthesia to be just as effective as IV anesthesia, but these patients tend to leave the ER more quickly because they do not have to allow time for the anesthesia to wear off.

There are several maneuvers that can be used to reposition a shoulder dislocation--usually each physician has a favored reduction maneuver. In general, the goal is to manipulate the bones to allow them to slide back into position without causing further damage to the shoulder joint.

Once the should dislocation is back in place, repeat x-rays are performed to ensure it is indeed in the correct position, and to evaluate for other injuries such as fractures. Patients are placed in a sling to rest the shoulder and referred to their orthopedic surgeon for further management.

Is further treatment needed for a shoulder dislocation?
Patients who sustain a shoulder dislocation are much more likely to have another shoulder dislocation. The reason is that when a shoulder dislocation occurs, ligaments within the shoulder are torn, and the shoulder joint becomes less stable.

Most often a patient will be examined by their orthopedic surgeon. If a shoulder dislocation occurred, the examiner will look for signs of injury to the ligaments in the shoulder--most often the so-called Bankart lesion. This may include some specific tests to evaluate for shoulder instability. A MRI test may be obtained to look for the Bankart lesion. If ligament damage is diagnosed, a decision about whether or not to proceed with surgical treatment must be made.