Shoulder Dislocation & Instability Fracture
The shoulder joint (glenohumeral joint) is made up of a ball and socket joint. The flat bone of the socket has surrounding tissue called the labrum. The labrum gives it the extra depth it needs to help hold the ball in the socket. Ligaments of the joint capsule provide additional support. When the ball comes out of the socket during a dislocation, a portion of the labrum is torn or separated from the socket. Depending on the location of the tear, this is called a Bankart tear or SLAP (Superior Labral tear from Anterior Posterior Lesion). In addition, the capsule may become stretched.
A dislocated shoulder happens when a strong force or extreme shoulder rotation pulls the "ball" of the upper arm bone right out of the socket. About 90% of all shoulder dislocations are this form of injury, called "anterior dislocation".
If the dislocation is partial, it's called subluxation. The joint is loose and may slide partially out of place. In this case, the labrum may still be attached, but the capsule is stretched out.
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.
There are several manoeuvres which can be used to reposition a shoulder dislocation. 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 shoulder 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 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. If you dislocate again and again, and if you find that your shoulder problem is interfering with your lifestyle, it may advisable to proceed to surgery.
This may be especially important if you normally enjoy participating in sports.