The painful shoulder.

Pain in the shoulder arises from a wide variety of abnormalities. The most common cause of acute pain in the nontraumatized shoulder is calcific tendonitis or bursitis readily identified by plain film radiography. On the other hand, the evaluation of chronic pain usually requires some combination of arthrography, CT, ultrasonography, and MRI to identify the source of the patients' complaints with certainty. The shoulder is rarely the site of a monoarticular process and is infrequently the dominant site of abnormality in a generalized articular disease. Clues to generalized disease processes are sometimes evidenced by changes within the shoulder present on the chest film. The source of pain in the shoulder was often elusive and puzzling to both the clinician and radiologist prior to the development of techniques such as arthrography, CT, and MRI that allow the precise delineation of soft tissue abnormalities. The judicious use of these techniques has, in large measure, helped to solve the puzzle.