While the broad range of motion the shoulder can attain makes it one of the most versatile joints in our body, it also makes it one of the most vulnerable to dislocation. And despite the stabilizing components including the cartilaginous glenoid labrum and muscles of the rotator cuff, the shoulder dislocates more than any other joint.
When a shoulder only partially dislocates, it is called a subluxation. The head of the upper arm bone, or humerus, is partially out of the socket, or glenoid. This can feel as unstable as a dislocated shoulder, reducing range of motion and prompting pain.
When the humerus completely slips out of the socket, it is called a complete dislocation. Both a partial and complete dislocation can cause muscles to spasm, increasing pain. While the shoulder can dislocate in a variety of directions – forward, backward or downward, nearly 95 percent of the dislocations seen are forward, or anterior, dislocations.
When a shoulder frequently dislocates, it is called shoulder instability.
Following patient history and a physical examination assessment, a closed reduction (realign the bone without open incision) may be performed in order to place the ball of the humerus back into the joint socket. This will immediately relieve pain.
A sling or other stabilizing device may also be indicated – accompanied by rest and cold compression to reduce swelling. A rehabilitation exercise program to improve range of motion begins once swelling subsides.
Patients who experience chronic, or repeated, dislocations despite conservative treatment may require surgery to repair weakened ligaments in the shoulder joint.