Shoulder separation common injury

A shoulder separation is a fairly common injury, especially in an athletic population. A shoulder separation is actually a dislocation of the acromioclavicular (AC) joint, the joint between the front of the scapula (shoulder blade) and the clavicle (collarbone). Some people mistake this for a shoulder dislocation, and vice versa. This is a very different injury than a shoulder dislocation.


It is common to think of the shoulder as a simple ball and socket joint. The end of the arm bone (humerus) ends in a ball that then plugs into the socket of the shoulder. Actually, the shoulder is made up of three bones: the scapula (shoulder blade), the humerus (upper arm bone) and the clavicle (collarbone).

The part of the scapula that makes up the roof of the shoulder is called the acromion. The joint where the acromion and the clavicle join is known as the acromioclavicular (AC) joint. There are ligaments that hold these two bones together. Ligaments are soft tissue structures that connect bone to bone. There is one set of ligaments that surround the joint and make up the joint capsule. Two other ligaments hold the clavicle down (coracoclavicular ligaments), and attach the clavicle to a bony knob on the scapula.

The AC joint can be injured in varying degrees. The simplest type injury is a simple sprain of the ligaments around the joint (Grade 1). A more severe injury can result when the ligaments around the joint are actually torn (Grade 2).

If the ligaments around the joint and that attach the clavicle to the scapula are torn, the injury results in an obvious bump on the shoulder (Grade 3).


The symptoms may range from simply tenderness over the joint, to a complete dislocation of the joint as seen in the Grade 3 separation. There may be a considerable amount of swelling if the separation is Grade 2 or 3. A bluish discoloration of the skin due to bruising may occur several days after the injury. In the Grade 3 separation you may feel a popping sensation due to the loose joint shifting. There is usually a noticeable bump on the shoulder if the joint has completely dislocated.


Diagnosis is usually made on physical examination. X-rays may show the acromioclavicular (AC) joint to be dislocated and may be necessary to make sure there is not a fracture of the clavicle. In some cases, X-rays are taken while holding a weight in each hand to stress the joint and determine how much instability in the joint is present.


Treatment for a Grade 1 or Grade 2 shoulder separation usually consists of a sling and pain medication until the sprain, or tearing, of the ligaments heals. In most cases, the shoulder becomes relatively pain free within three weeks. Since there is not a danger of making the condition worse, activity can be determined by the symptoms. You can usually do whatever you can tolerate.

The treatment of Grade 3 AC separations is somewhat controversial. Many studies show no difference in the outcomes for surgically treated separations versus doing nothing. Other physicians feel that some patients benefit from surgical repair.

Regardless, if you suspect that you have suffered an AC joint injury, you should be evaluated by your health care professional. Often an injury to the AC joint is accompanied by other injuries to the shoulder, neck and back.