In severe cases, ligaments, tendons, and nerves also can be stretched and injured. The most common type of dislocation is an anterior dislocation. It can be caused by a fall onto your outstretched hand or onto the shoulder itself. A posterior dislocation may occur as a result of a powerful direct blow to the front of your shoulder. It may also be caused by a violent twisting of your upper arm, such as that caused by an electric shock or seizure.
Dislocated shoulders are common in contact sports such as football, rugby, hockey, and lacrosse.
Other sports that may cause the injury include downhill skiing, volleyball, and soccer. You also may be genetically susceptible to a dislocation, particularly if your shoulder goes out often or easily. Other members of your family may have the same problem. The main symptom is pain in your shoulder and upper arm that is made worse by movement. If you have an anterior dislocation, you will find yourself holding your arm on the dislocated side slightly away from your body with your opposite hand.