Imaging of shoulder instability.

Multiple imaging modalities are used in the evaluation of the patient with known or suspected instability. Plain films are often the initial study and are useful in detecting fractures and assessing alignment. Magnetic resonance imaging, with its multiplanar capabilities, such as that of visualizing soft-tissue structures, is rapidly becoming the study of choice for shoulder instability. Ultrasonography and computed tomography arthrography have limited roles in the evaluation of the patient with instability.