Imaging the injured shoulder.

The shoulder is the most mobile and unstable of all the joints in the body, making it highly susceptible to instability and injury. Shoulder injuries often result from excessive or repetitive overhead arm motion. The 3 main categories of shoulder injury are instability, impingement, and rotator cuff injuries. Radiography is the most common screening modality for patients presenting with shoulder pain; however, ultrasonography, magnetic resonance, and computed tomography also are used widely in diagnosis. Treatment for shoulder injury varies with each condition, and surgery may be indicated for major injuries. This article reviews diagnosis and treatment for both common and uncommon shoulder injuries, as well as techniques for preventing injury.