Shoulder Dislocations

The shoulder is a ball and socket joint. Normally the ball (humeral head) sits inside the socket (glenoid). A shoulder dislocation occurs when the ball is no longer sitting inside the socket. Most shoulder dislocations are anterior dislocations (when the ball pops forward and sits in front of the socket). Posterior shoulder dislocations are much less common but more commonly occur after seizures or electrocutions. Some shoulders can dislocate in multiple directions (multi-directional instability), and this usually occurs in "double-jointed" ( ligamentously lax) individuals.

When a shoulder dislocates, it usually damages some structures in the shoulder joint. In the younger patient, the most common structure to be damaged is the glenoid labrum, which is a piece of cartilage on the rim of the socket which serves to make the socket deeper and attach the anterior ligaments. If this labrum gets ripped off the socket ( Bankart lesion) then the socket is shallower, the ligaments are no longer firmly attached and the shoulder is more prone to future dislocations. Repeated dislocations can damage the joint surface and lead to arthritis.

In a patient who is likely to have ongoing instability (contact athlete) or has recurrent instability affecting quality of life, surgery can be considered. Surgery involves restoring anatomy by reattaching the ligaments and labrum to the socket ( ie. Bankart repair or shoulder reconstruction). This is performed using specially designed small anchors placed into the edge of the socket. The anchors have stitches attached that are used to grab and secure the torn cartilage rim and ligaments back to the socket. I generally perform this procedure using arthroscopic (keyhole) techniques.

Every time a shoulder dislocates a little more damage is done to the shoulder. Sometimes, bone is worn away either from the socket (bony Bankart lesion) or the ball (Hill Sachs Lesion). If there has been too much socket bone loss to support the ball of the humeral head, then bone must be added order to make the shoulder stable. There are a number of techniques for addressing bone loss. I prefer taking a piece of local bone from the shoulder (coracoid) and transferring it to the socket (Laterjet procedure). See Bone Deficient Anterior Instability.

In the older patient with a shoulder dislocation, sometimes the muscles can be torn off. This is known as a rotator cuff tear. When this happens, the tear can be very large and the patient can lose the ability to raise their arm above their head. If the patient is otherwise well and not willing to accept the loss of function then a repair of the tendons can be considered.