The term shoulder separation refers to an injury of the ligaments that surround and stabilize the AC joint (acromioclavicular joint) at the juncture of the collarbone (clavicle) and highest point of the shoulder blade (acromion).
An AC joint separation is different from a dislocated shoulder and should not be confused. A shoulder dislocation occurs in the main shoulder joint where upper arm rests in its socket, while a separated shoulder occurs where the collarbone and the shoulder blade meet.
The AC joint helps to facilitate the overhead and across the body movements of your arm, as well as aid in transmitting forces from the arm to the rest of the body during activities such as pushing, pulling and lifting. The joint is stabilized by a number of ligaments and the surrounding joint capsule. However, large forces and the stress of repetitive movements make the AC joint vulnerable to both trauma and degenerative change.
One of the most common injuries at the AC joint is dislocation, often called a shoulder separation. This happens when the ligaments connecting the acromion and clavicle are damaged and the alignment of the two bones is disrupted.
A shoulder separation can result from a fall on the point of the shoulder, a direct blow to the AC joint area, or a spill onto an outstretched arm. It is a common injury in athletes.
The symptoms associated with a separated shoulder can range from mild to severe depending on the extent of the injury. The symptoms may include:
Limited/difficult shoulder and arm movement
Shoulder bruising or inflammation
A hard, visible bump on top of the shoulder indicating a displacement of the clavicle (collar bone)
Shoulder separations are graded from I to VI based on the severity of AC joint disruption, ligament damage and bone displacement. The lower grade injuries involving minor to moderate disruption of ligamentous support for the arm and shoulder can usually be managed conservatively and without surgery. High grade injuries require surgery to alleviate the severe symptoms, restore function, and correct the deformity.