Impingement of lesser trochanter on ischium as a potential cause for hip pain.

The bony anatomy of the hip leads to a limited array of impingement syndromes, more frequently resulting from abnormal contact between the femoral neck and acetabulum. We report an unusual case of osseous impingement between the lesser trochanter and ischium, with involvement of the intervening quadratus femoris muscle. While the prevalence and etiology of this finding is unclear, it may represent a cause for hip pain.