Dynamic sonography of snapping hip due to gluteus maximus subluxation over greater trochanter.

We report on the dynamic sonographic findings of a 10-year-old avid female dancer who presented with symptoms of abrupt left hip motion and associated painful snapping sensation while performing lateral motions of the pelvis suggesting external snapping hip syndrome. Dynamic sonographic evaluation of both hips demonstrated that symptoms were due to gluteus maximus subluxation over the greater trochanter. This etiology of external snapping hip syndrome is rare with limited imaging descriptions in the literature. We present case history, physical examination, and dynamic ultrasound examination, including multiple still images and cine clips, comprehensively characterizing this uncommon source of external snapping hip syndrome.