Medical Library: Shoulder – Joint Separation
A shoulder separation is an injury to the acromioclavicular joint on the top of the shoulder. The shoulder joint is formed at the junction of three bones: the collarbone (clavicle), the shoulder blade (scapula), and the arm bone (humerus). The scapula and clavicle form the socket of the joint, and the humerus has a round head that fits within this socket. Another name for this injury is an acromioclavicular joint separation, or AC separation.
Shoulder separation and shoulder dislocation are two commonly confused injuries, but they are very different conditions. In a shoulder dislocation, the humerus (arm bone) is displaced from the socket.
A shoulder 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 on to an outstretched hand (commonly seen after falling off a bicycle or horse).
Pain is the most common symptom of a separated shoulder, and is usually severe at the time of injury. Evidence of traumatic injury to the shoulder, such as swelling and bruising, are also commonly found.