A dislocated shoulder is an injury in which the upper arm bone pops out of the cup-shaped socket that is part of the shoulder blade. The shoulder joint is the body’s most mobile joint; it can turn in many different directions. The advantage of this flexibility to move makes the joint inherently unstable, and also makes the shoulder susceptible to dislocation. It is the most commonly dislocated large joint in the body.

Dislocations of the shoulder occur when the head of the humerus is forcibly removed from its socket in the glenoid fossa. It’s possible to dislocate the shoulder in many different directions, and a dislocated shoulder is described by the location where the humeral head ends up after it has been dislocated. In a severe case of a dislocated shoulder, the tissue and nerves around the shoulder joint are damaged. 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 dislocations are associated with pain and unsteadiness in the shoulder.

Symptoms of A Dislocated Shoulder

Dislocated shoulder signs and symptoms may include:

  • Pain
  • Bruising
  • Swelling
  • Weakness
  • Deformation
  • Numbness
  • Inability to move the joint

Sometimes dislocation may tear ligaments or tendons in the shoulder, or damage nerves.

The shoulder joint can dislocate forward, backward or downward. A common type of shoulder dislocation is when the shoulder slips forward (anterior instability). This means the upper arm bone moved forward and down out of its joint. It may happen when the arm is put in a throwing position.

Causes of A Dislocated Shoulder

A dislocated shoulder may be caused by:

  • Sports injuries – Shoulder dislocation is a common injury in contact sports, such as football and hockey, and in sports that may involve falls, such as downhill skiing, gymnastics and volleyball.
  • Trauma not related to sports – A hard blow to the shoulder during a motor vehicle accident is a common source of dislocation.
  • A patient may dislocate their shoulder during a fall, such as from a ladder or from tripping on a loose rug.