Radiologic features of shoulder instability.

Roentgenographic studies in a patient with shoulder instability generally identify the presence of a Hill-Sachs lesion, the presence of bony abnormalities of either the anterior or posterior rim, the presence or absence of fractures, and thick pathologic changes in the joint structure, which not only may provide insight into the diagnosis, but also may give the clinician insight into whether these pathologic changes are likely to be improved with operative and nonoperative treatment modalities. Clearly, the anteroposterior view, particularly with internal rotation, seems important in the diagnosis of the unstable shoulder. The West Point axillary view seems to be a useful one to identify the presence of glenoid rim problems. An additional view, such as the Stryker notch view, may identify the extent and presence of Hill-Sachs lesion when this may not be present on the other two views. Computed tomography arthrography, magnetic resonance imaging scan, and stress testing probably has limited applicability in the routine roentgenographic diagnosis of the unstable shoulder.