The shoulder joint is the body’s most mobile joint. It can turn in many directions. But, this advantage also makes the shoulder an easy joint to dislocate. A partial dislocation (subluxation) means the head of the upper arm bone (humerus) is partially out of the socket (glenoid). A complete dislocation means it is all the way out of the socket. Both partial and complete dislocation cause pain and unsteadiness in the shoulder.
A dislocated shoulder is an injury in which your upper arm bone pops out of the cup-shaped socket that’s part of your shoulder blade. A dislocated shoulder is a more extensive injury than a separated shoulder, which involves damage to ligaments of the joint where the top of your shoulder blade meets the end of your collarbone. If you suspect a dislocated shoulder, seek prompt medical attention. Most people regain full shoulder function within a few weeks after experiencing a dislocated shoulder. However, once you’ve had a dislocated shoulder your joint may become unstable and be prone to repeat dislocations.
The joint between the humerus and scapula, also called the glenohumeral joint, is a ball-and-socket joint–the ball is on the top of the humerus, and this fits into a socket of the shoulder blade called the glenoid. This joint is incredible because it allows us to move our shoulder though an amazing arc of motion–no joint in the body allows more motion than the glenohumeral joint. Unfortunately, by allowing this wide range of motion, the shoulder is not as stable as other joints. Because of this, shoulder dislocations are not uncommon injuries.
The shoulder joint is the most frequently dislocated joint of the body. Because it can move in many directions, your shoulder can dislocate forward, backward or downward, completely or partially. In addition, fibrous tissue that joins the bones of your shoulder (ligaments) can be stretched or torn, often complicating the dislocation.When your shoulder dislocates, a strong force, such as a sudden blow to your shoulder, pulls the bones in your shoulder out of place (dislocation). Extreme rotation of your shoulder joint, such as during a throwing movement, can pop the ball of your upper arm bone (humerus) out of your shoulder socket (glenoid), which is part of your shoulder blade (scapula).
Dislocation is the result of a traumatic injury, caused by extreme forces that stretch muscles, ligaments, and tendons. Sport injuries and vehicle accidents are prime causes of shoulder dislocations. The injury occurs when the Humeral Head (ball-like shape at the end of the Humerus) is forced out of its socket. This type of injury may also include fracturing or breaking of the Humerus (upper arm bone), torn soft tissue, chipping of the Labrum or Scapula (components of the shoulder), and even scraping of the shoulder’s Capsule (cup-like area soft tissue of the shoulder).
Shoulder dislocations are almost always anterior – that is, the head of the humerus moves forwards. In some rare cases, this can happen in the opposite direction, with the head of the humerus being forced backwards. This is known as a ‘posterior dislocation’, and is more common following a fit, or if falling on an outstretched hand. The arm will tend to be held into the body (in internal rotation and adduction), and as this is slightly harder to reduce, X-Rays are very important. If possible a Lateral and/or Axillary view is needed to check for fractures.