An unusual cause of external snapping hip.

The external snapping hip syndrome is a condition characterized by palpable or audible snap on the lateral region of the hip occurring during movements and sometimes associated with pain. It is typical of young adults and athletes and can be favored by the abnormal sliding of the iliotibial band or of the gluteus maximus muscle over the greater trochanter. We present a case of external snapping hip syndrome occurring in a young woman secondary to a dysmorphic sickle-shaped myotendinous junction of the gluteus maximus muscle. Diagnosis was allowed by an integrated clinical and radiological approach, based on dynamic ultrasound and magnetic resonance imaging (MRI).