Ischiofemoral impingement

Dr Henry Knipe and Dr Tim Luijkx et al.

Ischiofemoral impingement refers to the impingement of soft tissues between the ischial tuberosity and lesser trochanter of the femur, primarily the quadratus femoris muscle manifesting with muscle belly edema. Narrowing of the distance between these two osseous landmarks (ischiofemoral space and quadratus femoris space) predisposes for and correlates with symptomatic ischiofemoral impingement.

Ischiofemoral impingement is a rare cause of buttock pain, groin pain, or a snapping hip 6,7.

Females are more affected than male. Ischiofemoral narrowing may be bilateral but symptoms may only be unilateral 3,9

There are numerous causes for narrowing of the ischiofemoral and quadratus femoris space including 2,4,9:

A recent study suggested ischiofemoral impingement is likely in patients with chronic pelvic pain if the ischiofemoral space is <2 cm or <1.9 cm on supine and standing pelvic x-rays, respectively. It warrants further investigation by pelvic MRI 5.

  • T1
    • ischiofemoral space is measured on an axial T1 sequence
      • shortest distance between medial cortex lesser trochanter and lateral cortex ischial tuberosity 8
      • cut-off: ≤15 mm (sensitivity 77%, specificity 81%, accuracy 74%) 1
    • quadratus femoris space is measured on an axial T1 sequence
      • smallest distance for the passage of quadratus femoris between the posteromedial iliopsoas tendon or ischial tuberosity and the superolateral hamstring tendons 8
      • cut-off: ≤10 mm (sensitivity 79%, specificity 74%, accuracy 77%) 1,9
    • fatty atrophy of quadratus femoris may be present 9
  • STIR/T2 FS
    • quadratus femoris muscle belly edema and/or tears 9
    • muscle belly edema may extend to the hamstrings and/or iliopsoas muscles 9

Ischiofemoral impingement was first described as a cause for hip pain by K A Johnson in 1977 4

Article information

rID: 39031
Section: Syndromes
Synonyms or Alternate Spellings:
  • Quadratus femoris impingement
  • Ischiofemoral impingement (IFI)
  • Ischiofemoral impingement syndrome

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Cases and figures

  • Figure 1: bilateral - annotated MRI
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  • Case 1: bilateral IFI
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  • Case 2: left-sided IFI
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  • Case 3
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  • Case 4
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  • Case 5: right sided
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