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.