Atypical Thigh Pain in the Elderly
Overview
Atypical femoral fractures (AFFs) are low‑energy stress fractures of the femoral shaft that classically present with prodromal thigh, groin or hip pain. They are uncommon but important to recognise in older adults because incomplete lesions may progress to complete shaft fractures with high morbidity.
AFFs are most often reported in association with long‑term antiresorptive therapy (bisphosphonates) and, more rarely, denosumab (MHRA).
The absolute risk is low compared with the benefits of fracture prevention, but emergency clinicians must identify at‑risk patients promptly and initiate appropriate imaging, weight‑bearing precautions and specialist referral (MHRA; NICE QS149).
Pathology and epidemiology
AFFs are focal stress reactions or insufficiency fractures of the femoral diaphysis thought to arise from suppressed bone remodelling and impaired micro‑crack repair. Typical features include:
- Typical location: subtrochanteric region to femoral shaft - from just below the lesser trochanter to just above the supracondylar flare (MHRA).
- Fracture pattern: often transverse or short oblique and minimally comminuted; incomplete fractures commonly involve the lateral cortex only (MHRA).
- Bilaterality is common; contralateral lesions are frequently asymptomatic.
- Most reported cases are associated with prolonged bisphosphonate use (often several years), but the absolute event rate is low (NICE; MHRA).
- Rare cases have been reported in association with denosumab.