Shoulder Dislocation Pathology
Any movement of the humeral head out of the socket can result in damage to your shoulder joint. Younger people tend to damage the labrum, while people over the age of 40 years tend to tear a rotator cuff muscle. Below are some common presentations and injuries that can occur when you dislocate or sublux your shoulder.
When a shoulder dislocates or subluxes the cartilage (labrum) that deepens the socket can be torn (see below). This typically happens in the front and bottom of the socket. The tear that occurs in the labrum is called a Bankart lesion. Sometimes Bankart lesions are described as if the glenoid fossa socket is a clock face, with 12 at the top of the circle and 6 at the bottom. Thus this image shows a lesion from 2 to 6. If your shoulder dislocates out the back (posteriorly) then you may get damage in the posterior labrum, from 7-10 o'clock for example.
Bony Bankart Lesion
Sometimes the bone can also be damaged. It is known as a bony Bankart lesion
Hill Sachs lesions
A Hill Sachs lesion can occur when your humerus comes out of its socket. The bone is the humeral head is softer than the bone of the glenoid socket (fossa) (see below). This causes an indentation in the bone in the humeral head. Typically in an anterior dislocation this occurs in the top of the humeral head at the back. In a posterior dislocation, you may get damage in the top of the humeral head at the front. This is called a reverse Hill Sachs lesion.
Hill Sachs lesions are definitive proof that your shoulder has come out of its socket. Small Hill Sachs lesions are often not a problem. Large Hill Sachs lesions (around 40% of the humeral head) can affect the ongoing stability of the shoulder as the smooth contact surface of the bone is affected. Large lesions may get wedged on the glenoid fossa and get stuck. These are called engaging lesions, as opposed to lesions that do not get stuck (non-engaging)
Humeral Avulsion of the Glenohumeral Ligament (HAGL)
A HAGL lesion is when the shoulder capsule is torn from the end that attaches to the humerus (see below). This is lesion occurs at the opposite end of the capsule than a Bankart lesion (which occurs on the glenoid side). They commonly occur when the arm is over extended backwards. It is a common injury in rugby players, and men are much more likely than women to have this kind of lesion. Although some authors have documented that HAGL are usually associated with higher levels of recurrence than Bankart lesions, other authors have reported that they recover well without surgery.