What is shoulder dislocation?
A dislocated shoulder is the most frequently occurring dislocation to any joint in the body. It is a painful injury that happens when a fall or accident causes the top of your upper arm bone (humerus) to pop out of your shoulder joint’s cup-shaped socket (glenoid—part of your shoulder blade), also known as a glenohumeral dislocation.
A direct fall onto the shoulder also may cause a dislocation of the collar bone (clavicle) away from the shoulder blade (acromion) that causes discomfort at the acromioclavicular (AC) joint. The injury that causes dislocation of the shoulder may also stretch or tear the tendons and ligaments (fibrous tissues) that normally hold your shoulder in place. Nerves or blood vessels around the joint also may be affected. Broken bones, such as the top of the humerus, may be an additional complication.
Types of shoulder dislocations
There are many types of shoulder dislocations:
- (Anterior) forward and downward shoulder dislocation—This is the most common type of shoulder dislocation (about 95 percent of cases). In this type of shoulder dislocation, your shoulder will usually look square instead of round. You probably won’t be able to move the arm without acute pain. You might also see a lump at the top of the arm bone under the skin in front of your shoulder. This is most likely the type of injury you would have if you’ve fallen with an outstretched arm.
- (Posterior) backward shoulder dislocation—Not as common (about 5 percent of cases), this type of shoulder dislocation can be more difficult to spot without expert orthopedic consultation. In this case, the bone pops out of the back of the shoulder joint. This injury may occur even in people who are extremely flexible, such as gymnasts.
- (Inferior) downward shoulder dislocation—Very uncommon (in less than 1 percent of cases), this type of shoulder dislocation occurs with very significant trauma (e.g., a motorcycle accident). Your arm will be stuck above your head if you have this type of dislocation.
- (Subluxation) partial shoulder dislocation—The head of the upper arm comes partially out of the shoulder socket and pops back into place by itself. There may be a feeling that your shoulder feels loose and may want to dislocate again. Orthopedic consultation is recommended with this type of injury.
- AC dislocation—Common injury of the shoulder typically due to a fall directly onto the shoulder. It will cause pain at the top of the shoulder over the AC joint and difficulty when trying to move your arm. It also may look as if your shoulder is sagging, with perhaps even a noticeable deformity at the front of the shoulder.
Pain in the upper arm and shoulder that worsens during movement is the most common symptom of a dislocated shoulder. You may also experience these symptoms:
- Pain in your upper arm and shoulder, which is usually worse during movement
- Numbness and weakness
- Deformity of the shoulder
Men experience shoulder dislocations more than women do, and people in their teens and 20s experience a higher level because of their involvement in contact sports and activities that may involve falls, such as:
- Downhill skiing
- Mountain climbing
Among older adults (especially people over 50), the most common causes of dislocated shoulder are:
- From ladders
- Tripping over a loose rug
- Slipping on an icy surface
- Automobile accidents
Treatments depend on the nature of the injury as well as the age of the patient, and typically include nonsurgical treatments such as manually moving the arm bone back into the shoulder socket (reduction), temporary immobilization, therapy and medications. If those approaches do not relieve the pain, or if there is another injury to the shoulder (such as a rotator cuff tear or labral tear), or if you have repeat episodes of shoulder dislocation, surgery may be recommended. Full recovery time can take approximately 12–16 weeks if surgery is warranted.