Radiographic evaluation of the Hill-Sachs lesion in patients with recurrent anterior shoulder instability.

The Hill-Sachs lesion is an important bony sign of previous anterior shoulder dislocation and instability. Using orthographic projection, we evaluated the Hill-Sachs lesion in 30 shoulders in 27 patients with recurrent anterior shoulder instability. This produced a clear and undistorted view of the posterolateral notch. For orthographic imaging, the patient was placed supine with the arm in 135 degrees of flexion and 15 degrees of internal rotation. The x-ray beam was angled vertically through the humeral head. The width and depth of the posterolateral notches were measured on the orthographic radiographs. The average posterolateral notch depths were 3.9 +/- 0.9 mm in the dislocation group and 2.1 +/- 1.0 mm in the subluxation group. A shallow Hill-Sachs lesion was indicative of a greater degree of anterior instability of the shoulder.