injuries and poisoning
Shoulder Dislocation
Introduction
Shoulder dislocations occur when the ball-shaped head of the upper arm bone (humerus) pops out of its rounded socket in the shoulder blade (scapula). When the shoulder is dislocated, it is usually forcefully pushed forward out of the joint. The shoulder may look distorted and is usually very painful. Often, doctors can diagnose a dislocated shoulder by examining it, but x-rays are taken to confirm it. Doctors can usually put the joint back in place without surgery, often after people are given drugs to help them tolerate the procedure. (See also Overview of Dislocations .) The shoulder is the most commonly dislocated large joint. In over 95% of shoulder dislocations, the upper arm bone is pushed forward out of the joint (anterior dislocation). But occasionally, it is pushed backward or downward. Usually, a backward (posterior) dislocation occurs when a person has a seizure or receives an electric shock (for example, in a lightning injury). Downward dislocations are rare and usually obvious. Most people with a downward dislocation hold their arm over their head, typically with the forearm resting on the head. The bone may be pushed all the way out of the joint—called a complete dislocation—or part way out—called a partial dislocation (subluxation). The shoulder may be dislocated when strong force (such as a sudden blow) pulls, pushes, or twists the shoulder out, up, or back. Usually, the shoulder is pulled and rotated out. Common causes are sports injuries (such as blocking a shot while playing basketball), a car crash, and falls. When a shoulder is dislocated, tissues around the joint, such as ligaments, tendons, blood vessels, and nerves, may also be stretched or torn. Sometimes a bone, usually the top of the arm bone, is broken, especially in people over 45. If the injury was severe or if people, particularly those under 30, dislocate their shoulder several times (for example, by continuing to play sports), the shoulder may become unstable and more likely to be dislocated again. 