A, The glenoid track is calculated as 84% of the actual glenoid width measured on the sagittal oblique MR image. A best-fit circle is placed on the glenoid to calculate the expected width before bone loss; therefore, both percentage of bone loss and glenoid track can be determined. In this case, the actual glenoid width is 24 mm, with 4 mm of bone loss (17%). The glenoid track is 84% of 24 mm, or 20.1 mm. B, The distance from the rotator cuff footprint to the medial margin of the Hill-Sachs lesion is measured on the coronal MR image. In this case, it is 23.1 mm. Because the Hill-Sachs width to the footprint (23.1 mm) is greater than the glenoid track measurement (20.1 mm), it is considered outside the glenoid track and at high risk for engaging.