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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 Hill-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 Hill-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 Hill-Sachs lesion is best differentiated from the anatomic groove by means of its more cephalic position along the longitudinal humeral axis.