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Suspected incomplete atypical femoral fracture associated with long-term alendronic acid — MSRA MCQ

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HardHip and GroinSuspected incomplete atypical femoral fracture associated with long-term alendronic acidMSRA

A 76-year-old woman presents with a 5-week history of progressively worsening right lateral thigh pain that occasionally radiates to the groin. It is worse on walking and when rising from a chair. She has had no fall or other trauma. She takes alendronic acid 70 mg weekly, started 7 years ago after a vertebral fragility fracture. She is afebrile and systemically well. Hip flexion, internal rotation and external rotation are full and do not reproduce her pain. There is no focal lumbar tenderness or neurological deficit. An anteroposterior pelvic radiograph obtained at an urgent treatment centre 10 days ago was reported as normal. What is the most appropriate next step?

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Correct answer: B — Withhold alendronic acid pending evaluation and arrange prompt imaging of the whole right femur for an incomplete atypical fracture

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

This presentation should raise concern for an incomplete atypical femoral fracture (AFF). The discriminating features are prolonged bisphosphonate exposure, atraumatic progressive thigh/groin pain provoked by weight-bearing, and painless unrestricted hip movement. AFFs may produce prodromal thigh or groin pain for weeks to months before a complete fracture, and may arise anywhere from below the lesser trochanter to above the supracondylar flare. Therefore, a normal pelvic radiograph does not adequately evaluate the femoral shaft. Alendronic acid should be withheld while the patient is evaluated, and imaging must assess the symptomatic whole femur for an incomplete lesion. A is inappropriate because the examination does not support symptomatic hip osteoarthritis and delay risks fracture completion. B recognises that treatment duration requires review, but DEXA does not investigate the current potentially unstable femoral lesion. C may appear reasonable after a normal pelvic film, but it fails to address the bisphosphonate-associated shaft fracture risk and unnecessarily focuses on the hip joint. E prematurely commits to permanent cessation and specialist osteoporosis treatment before diagnosis and individual fracture-risk reassessment.

Reference: Alendronic Acid 70 mg Tablets - Summary of Product Characteristics (21 May 2026) — https://www.medicines.org.uk/emc/product/100151/smpc