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Femoral-head avascular necrosis — MSRA MCQ

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HardHip and GroinFemoral-head avascular necrosisMSRA

A 38-year-old woman presents with 6 weeks of progressive left groin pain. It initially occurred only after walking but now wakes her at night and is associated with a limp. There has been no trauma, fever, weight loss or back pain. She completed treatment for acute lymphoblastic leukaemia 18 months ago, including several courses of high-dose dexamethasone. She is in remission. Examination shows an antalgic gait and painful restriction of left hip internal rotation. There is no focal greater-trochanteric tenderness, neurological deficit or systemic illness. CRP, full blood count and renal function are normal. An anteroposterior pelvis radiograph shows preserved joint spaces with no fracture or destructive lesion. What is the most appropriate next step in primary care?

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Correct answer: C — Make an urgent orthopaedic referral for suspected femoral-head avascular necrosis

Explanation lettering: D = shown as A · A = shown as B · E = shown as C · C = shown as D · B = shown as E

This presentation is most concerning for femoral-head avascular necrosis (AVN). The key linked features are prior exposure to repeated high-dose systemic corticosteroids, progressive deep groin pain with worsening weight-bearing tolerance and pain at rest, and painful loss of hip internal rotation. A normal early plain radiograph does not exclude AVN: radiographic changes may be absent before structural femoral-head damage develops, whereas MRI can identify early disease. Urgent orthopaedic referral is appropriate because suspected AVN requires timely specialist assessment and imaging, with management determined by disease stage and femoral-head morphology. Delay risks femoral-head collapse and secondary osteoarthritis. A is inappropriate because physiotherapy alone may delay assessment of a structural, potentially progressive disorder. B is unsuitable because intra-articular corticosteroid injection treats symptomatic inflammatory or osteoarthritic pain but does not establish the diagnosis and is particularly unattractive in someone whose risk factor is corticosteroid exposure. C is inadequate because repeating plain films delays more sensitive assessment. D underestimates the atypical age, rapid progression, steroid exposure and normal radiograph, which are not typical of straightforward hip osteoarthritis.

Reference: Hip pain (Reviewed 12 November 2024) — https://www.rightdecisions.scot.nhs.uk/dg-refhelp/musculoskeletal-system/hip-pain/ A Patient's Guide to Avascular Necrosis (AVN) (2025) — https://www.rnoh.nhs.uk/patients-and-visitors/patient-information-guides/patients-guide-avascular-necrosis-avn