A Pain in the Buttocks: Practice Article for Sonographically Imaging the Quadratus Femoris and Ischiofemoral Impingement.

Ischiofemoral impingement (IFI) results in buttock, hip, and groin pain which can radiate down the leg. Clinical diagnosis of IFI is challenging due to the overlap of other syndrome symptoms, which can delay appropriate management. Hip external rotation reduces the ischiofemoral and quadratus femoris (QF) spaces, compressing the QF muscle between the ischial tuberosity and the lesser trochanter. Ultrasound imaging can demonstrate dynamic entrapment of the QF, including assessment of symptom provocation and concurrently identify injury or irritation of nearby structures including the peri-QF fat, sciatic nerve, and proximal hamstring tendons.