A shoulder separation is a fairly common injury, especially in certain sports. Most shoulder separations are actually injuries to the acromioclavicular joint (also called the AC joint). The AC joint is where the collarbone (clavicle) meets the highest point of the shoulder blade (acromion). AC joint separations and shoulder dislocations are often mistaken for each other, but they are very different injuries.

Causes

The most common cause of an AC joint separation is falling directly on the shoulder. As the shoulder strikes the ground, the force from the fall pushes the scapula down. The collarbone, because it is attached to the rib cage, cannot move enough to follow the motion of the scapula. The result is that the ligaments around the AC joint begin to tear. This causes the “separation” of the collarbone and wing bone. The wing bone actually moves downward from the weight of the arm. This creates a “bump” or bulge above the shoulder.

The injury can range from a little change in configuration with mild pain, to quite deforming and very painful. Good, pain-free shoulder function often returns even with a lot of deformity. The greater the deformity, the longer it takes for pain-free functions to return.

A mild shoulder separation involves a sprain of the AC ligament that does not move the collarbone and looks normal on X-rays.

A more serious injury tears the AC ligament and sprains or slightly tears the coracoclavicular (CC) ligament, putting the collarbone out of alignment to some extent.

The most severe shoulder separation completely tears both the AC and CC ligaments and puts the AC joint noticeably out of position.

Surgical Treatment

While conservative treatment is often used first for AC joint injuries, surgery may be required for injuries that are more severe or those that cause prolonged pain. Surgery for AC joint injuries may involve removing the end or restoring the position of the clavicle to relieve pain and allow the patient to resume normal functioning of the joint. Where there is significant deformity, reconstructing the ligaments that attach to the underside of the collarbone is required. To achieve this, the ligaments are brought together and a heavy suture or surgical screw is inserted through the clavicle and into part of the scapula to hold the joint in place during healing.

After surgery, the patient may be required to stay in the hospital for a couple of days for observation. The arm will need to be kept in a sling. Physical therapy will be necessary in order for the joint to heal properly. If a suture is used, it will remain, but if a surgical screw is used, it will be removed six to eight weeks after the surgery.