Acromioclavicular Joint

A sprain of the Acromioclavicular Joint is commonly referred to as a "shoulder separation" not to be confused with a shoulder dislocation which often refers to the glenohumeral joint. AC joint sprains are one of the most common joint injuries. It is most often caused by direct trauma such as a fall onto the shoulder or outstretched hand.

There are 4 ligaments that stabilize the AC Joint. The most commonly injured ligament is the Acromioclavicular Ligament. AC Joint injuries are graded by severity in the same way that all joint injuries are graded. Grade I injuries are the least severe and the ligament remains fully intact. Grade II injuries involve a rupture of the AC ligament but the other ligaments remain intact or are partially torn. In Grade III sprains all the ligaments are torn and a complete separation of the AC joint occurs.