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Rady Children's Specialists

Shoulder Separation (Acromioclavicular Joint injury)

A shoulder separation is an injury to the acromioclavicular joint, which is formed at  the junction of the collarbone (clavicle) and the shoulder blade (scapula). The end of  the scapula is called the acromion, and the joint between this part of the scapula andclavicle is called the acromioclavicular joint.

When this joint is disrupted, it is called a  shoulder separation, or AC separation. This is different than a shoulder dislocation  that involves the scapula and the arm bone (humerus).  An AC separation is almost always the result of a sudden, traumatic event that can  be attributed to a specific incident or action. The two most common descriptions of a  shoulder separation are either a direct blow to the shoulder (often seen in football,  rugby or hockey), or a fall onto an outstretched hand (commonly seen after falling  off a bicycle or horse).


Symptoms of a shoulder separation include:

  • Pain at the AC joint.
  • Evidence of trauma to the shoulder, such as swelling and bruising.


The diagnosis of shoulder separation is often quite obvious from the described injury  and the physical examination. An X-ray is done to be sure that there are no  fractures. Sometimes, if the diagnosis is unclear, an X-ray while holding a weight in  your affected hand may be helpful to demonstrate the increased space in the AC  joint.


Since not every shoulder separation is the same, treatment is not the same for each  injury. It all depends on the grade, or severity, of the separation. A grade I AC  separation is an injury to the capsule that surrounds the AC joint, and the bones are  not out of position.

A grade II AC separation involves at least one of the important  ligaments that stabilizes the clavicle, and there is an actually separation noticed on  exam. Neither of these grades requires surgery and can be treated with a period of  rest, perhaps some physical therapy.

A grade III AC separation is a more significant grade II (treatment is controversial,  surgery vs. no surgery). The higher grades (4- 6) all require surgery, as they involve  more structures and poor shoulder function.