If you are suffering from a shoulder injury, you might hear the terms “shoulder dislocation” and “shoulder subluxation” during the examination and wonder if they are the same thing. There is a subtle difference in these two shoulder injuries, but both have an impact on how the joint functions.
If you do have a shoulder injury, understanding the basics of the joint and the difference between these two problems will help during your recovery and rehabilitation.
The shoulder joint is loosely fixed so you can do things like reach up and catch a ball or grab something off a shelf. This mobility is also what makes the shoulder dislocate more often than other similarly designed joints. Picture one of your hands forming the letter “C.” Now imagine balling up the other hand into a fist and sliding it into the “C.” This is a basic synovial ball and socket joint like the one that allows you to move your arm.
Medically, the shoulder is the glenohumeral joint. Your shoulder is where the glenoid fossa, the “C” figure or socket, of the shoulder blade meets the ball head of the humerus, the large upper bone in your arm. There is a capsule of connective tissue that sits around the joint to help keep the ball inside the “C.”
A shoulder can move in any direction and has the potential to dislocate in many different ways. The joint movement relies on the ball and socket remaining aligned to function properly. A hard hit to the shoulder is enough to change that alignment and cause injury.
What is a Shoulder Dislocation?
When you have a shoulder dislocation it means the ball and socket of the joint have fully separated. The ball section of the humerus has detached fully from the glenoid fossa.
This is a common injury because the glenoid fossa, or socket of the joint, is very shallow, allowing the humerus bone to become loose without much force. The majority of dislocations are anterior, so the ball section of the humerus pulls out of the socket and is pushed towards the front of the body.
This is an injury that can happen when you fall. The natural instinct is to put your hands out in front of you to try to stop the fall. As you hit the ground, the ball in the shoulder joint pops out, or dislocates, and move towards the front.
What is Shoulder Subluxation?
Shoulder subluxation is a type of dislocation, but the ball and socket are not fully separated. The two structures of the joint are still in contact, but one has shifted out of alignment. Damage to the supporting architecture, like the muscles or tendons, can weaken the joint and allow the subluxation. For example, when a baseball player suffers an injury to his rotator cuff it may result is a shoulder subluxation. The rotator cuff is a group of muscles and connective tissue that holds the joint together. If the muscle tears, the ball of the joint may come loose enough to let the humerus bone shift out of place while still remaining housed in the glenoid fossa.
A dislocation involves the structures of the shoulder while a subluxation usually is about the mechanical integrity of the shoulder and its supporting structures.
How to Tell When You’re Injured
Despite the key differences of these two injuries, they have some similar symptoms – the two most obvious being pain and inability to move the arm. Your natural tendency will be to support the weight of your arm with your other hand. There may be bruising and swelling around the joint, as well as numbness and tingling in the arm and muscle spasms near the shoulder.
A shoulder dislocation may look visibly deformed, however. The ball has separated completely from the socket, so the shoulder may square off and look like it is at an odd angle. Oftentimes, there may be an associated fracture with the dislocation.With a shoulder subluxation, you may notice a bump at the top of the shoulder. This is the ball of the joint protruding outside the glenoid fossa.
The treatment of these two injuries depends on a number of factors such as whether the ball of the humerus is fully dislocated and the extent of the damage to the connective tissue around the joint. A full shoulder dislocation can cause injury to the auxiliary structures of the shoulder like the nerves or blood supply. Coaxing the ball back into the socket relieves the pain, but can cause further damage without proper rest and rehabilitation.
For shoulder subluxation, the goal is to treat the mechanical problem such as a torn rotator cuff so the shoulder can heal.
The best course of action is to immobilize the shoulder right away with a splint or sling if you think you have a sublimation or dislocation. Put ice on the joint to reduce the swelling and relieve some of the pain. The next step is to get emergency medical attention for a proper diagnosis of the injury and to reduce the risk of permanent damage. Imaging will show the doctor the extent of the injury, so you can get the right treatment.
The care plan will include pain management, immobilization and physiotherapy. In some cases, the emergency physician might consult with an orthopedic surgeon to see if you are a candidate for surgical repair. Expect the recovery period to last between 12 weeks to up to six months, depending on the extent of the injury.
If you are suffering from shoulder pain, see a doctor to get a full evaluation. Dislocations and subluxations are just two possible causes of your pain, but not the only ones. It is better to get a proper diagnosis from a certified specialist to avoid a more damage to the joint.