Ischiofemoral impingement and the utility of full-range-of-motion magnetic resonance imaging in its detection.

Ischiofemoral impingement is a cause of hip pain resulting from compression on the quadratus femoris muscle between the ischium and femoral lesser trochanter. The most widely accepted diagnostic criterion is hip pain with isolated edema-like signal in the ipsilateral quadratus femoris muscle on magnetic resonance imaging (MRI). Additional criteria based on measurements of the ischiofemoral and quadratus femoris spaces have recently been suggested. However, because these measurements are positioning-dependent, we used full-range-of-motion MRI to increase the diagnostic yield. By evaluating through a range of motion, we detected a case of impingement involving the ischial tuberosity and the lesser trochanter, with probable contributing impingement between the ischial tuberosity and greater trochanter. In this article, we briefly review the topic of ischiofemoral impingement, provide an example of how range-of-motion MRI can improve diagnostic accuracy, describe our protocol, and propose exploring the need for an expanded definition of the impingement criteria.