There are two primary joints in the shoulder. The glenohumeral joint is where your upper arm connects with your shoulder. This is also known as the “ball and socket” joint because of the way these structures are shaped. When the ball becomes partially or completely out of the socket, this is known as a shoulder dislocation.
The acromioclavicular joint (also known as the AC joint) is where your shoulder connects with your collarbone. When the structures in this area move too far apart from each other and no longer line up correctly, this is known as a shoulder separation.
Both shoulder dislocation and shoulder separation involve the bones in the area moving too far apart from each other – either partially or completely out of place. Both injuries also often include partially or fully torn ligaments. As you can see, shoulder separation and shoulder dislocation are very similar to one another. The key difference is whether you’ve injured your glenohumaral joint or your AC joint.