There are several types of shoulder dislocations. They are named based on the direction of the dislocation.
The most common type is the anterior dislocation where the shoulder comes out the front. Another type of shoulder dislocation is posterior: this is where the shoulder dislocates out the back.
A posterior shoulder dislocation is rare. Anterior shoulder dislocations occur 15-21 times more often than a posterior shoulder dislocation but the etiology of the posterior dislocations are consistent. We see this in people who have had seizures, high energy trauma such as an auto accident, or have been electrocuted.
The posterior shoulder dislocation gets missed or has a delay in diagnosis up to 79 percent of the time.
The orthopedic doctor should be suspicious of additional injuries associated with a posterior shoulder dislocation. Up to 55 percent of the time there is an associated neck injury and 23 to 42 percent of the time a fracture involving the shoulder bone (greater and lesser tuberosity) occurs at the time of the posterior shoulder dislocation.
If the dislocation is caught early after the injury, a closed reduction can be performed in the emergency department. This is performed with a light anesthetic. If the dislocation is missed and becomes chronic, an open reduction may need to be performed in the operating room.