The term “shoulder separation” is not the same as the term “shoulder dislocation.” Dislocation of the shoulder implies that the main shoulder joint comes apart to where the “ball” (head of the humerus, or arm bone) is no longer on the “saucer” (glenoid process of the scapula, or shoulder blade). In contrast, shoulder separation indicates that a much smaller joint, called the acromioclavicular joint, has been injured. The acromioclavicular joint is basically the articulation of the clavicle (collarbone) and the acromion process of the scapula (shoulder blade). This small joint is located directly above the main shoulder joint and is often injured from direct blows to the top of the shoulder or from being thrown and landing on the top of the shoulder when one hits the ground. Such an injury drives the acromion process down while the collarbone maintains its position. This ruptures ligaments connecting the two bones and causes the collarbone to “rise up” compared to the acromion. Consequently, a bump on the top of the shoulder is often created with this injury.
There are many different grades of shoulder separation. Most can heal in the sense that the swelling and discomfort go away and function returns, even if the relationship between the collar bone and the acromion is not restored. However, if there is a wide degree of separation, patients often have persistent pain and weakness. These wider degrees of separation often require surgical reconstruction in order to bring the collarbone back down to a more normal position in relation to the scapula.