The quadratus femoris is the most inferior of the six deep external hip rotators, running horizontally from the ischial tuberosity to the intertrochanteric crest. The ischiofemoral space — the gap between the lesser trochanter and the ischial tuberosity through which the quadratus femoris passes — is narrowed in ischiofemoral impingement, causing quadratus femoris muscle oedema and tearing.
| Origin | External surface of the ischial tuberosity (lateral border) |
|---|---|
| Insertion | Intertrochanteric crest of the femur (quadrate tubercle) |
| Nerve Supply | Nerve to quadratus femoris (L4, L5, S1) — a branch of the sacral plexus |
| Blood Supply | Medial circumflex femoral artery |
| Actions | Hip external rotation — the strongest external rotator with the hip in neutral; Hip adduction assistance |
|---|
Ischiofemoral impingement syndrome from narrowing of the ischiofemoral space (from femoral valgus, greater trochanteric avulsion, retroversion, or post-ORIF changes) produces the characteristic edema and fat stranding within the quadratus femoris on MRI. The condition is confirmed by measuring the ischiofemoral space (normal >17 mm) and quadratus femoris space (normal >8 mm) on coronal MRI.
The quadratus femoris is not independently palpable but its region at the ischial tuberosity lateral border may reproduce tenderness in ischiofemoral impingement.
Quadratus femoris compression in the narrowed ischiofemoral space producing characteristic MRI fat stranding managed with activity modification, injection, and occasionally surgical decompression.
