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AVN Staging — RACP Adult Medicine MCQ

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ModerateRheumatologyAVN StagingRACP Adult Medicine

A 60-year-old man on long-term corticosteroid therapy for COPD develops avascular necrosis (AVN) of the femoral head. MRI shows a crescent sign (subchondral collapse). What Ficat-Arlet stage is this?

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Correct answer: D — Stage III

The Ficat-Arlet staging of AVN: Stage 0 – preclinical (normal X-ray and MRI), Stage I – preradiographic (normal X-ray, abnormal MRI), Stage II – pre-collapse (sclerosis/cysts on X-ray, no subchondral collapse), Stage III – crescent sign (subchondral collapse/fracture but maintained sphericity), Stage IV – osteoarthritis (flattening of femoral head, secondary OA changes). The crescent sign on MRI or X-ray represents subchondral fracture = Stage III. Core decompression may help in early stages (I–II); Stage III–IV typically requires total hip arthroplasty.

Reference: eTG – 2025 – Rheumatology