Imaging findings in external snapping hip syndrome.

We describe a case of external snapping hip diagnosed by dynamic sonography. The case prompted us to retrospectively review the imaging findings of children who clinically had presented with snapping hip. From this review we identified the features on MRI and CT of either thickening of the iliotibial band or thickening of the anterior edge of the gluteus maximus muscle as the cause of snapping and atrophy of the bulk of gluteus maximus muscle as an important secondary sign associated with snapping.