HILL-SACHS LESION AND NORMAL HUMERAL GROOVE - MR-IMAGING FEATURES ALLOWING THEIR DIFFERENTIATION

PURPOSE: To present a method of differentiating Hill-Sachs lesions from the anatomic groove in the posterolateral humeral head with use of magnetic resonance imaging. MATERIALS AND METHODS: A 360 degrees reference about the humeral head was established to define the locations of HilI-Sachs lesions and the anatomic groove on transaxial images. The extension of each finding along the longitudinal humeral axis was noted. Eight cadaveric specimens were sectioned and similarly analyzed. RESULTS: The locations of HilI-Sachs lesions and the anatomic groove in the circular reference frame were statistically significantly different (P <.001), yet their respective ranges overlapped. Along the longitudinal humeral axis, there was no overlap between the respective ranges of location (P <.001). CONCLUSION: A HilI-Sachs lesion is best differentiated from the anatomic groove by means of its more cephalic position along the longitudinal humeral axis.