In Garden's classification of femoral neck fractures, which stage carries the highest risk of avascular necrosis of the femoral head due to complete disruption of the retinacular vessels?

• A Garden Stage I — incomplete, impacted in valgus
• B Garden Stage II — complete, non-displaced
• C Garden Stage IV — complete, fully displaced with trabeculae of head realigning with acetabular trabeculae ✓
• D Garden Stage III — complete, partially displaced

Explanation

Garden Stage IV is a completely displaced femoral neck fracture where the head has rotated so that its trabecular pattern re-aligns with the acetabulum (appearing normal on X-ray). The complete displacement ruptures the superior retinacular (lateral epiphyseal) vessels — the primary blood supply to the femoral head in adults — resulting in the highest AVN risk (~30–50%). Stages I and II have low AVN risk (<10%) because vascular disruption is minimal. Stage III has intermediate risk. Stage IV fractures in young patients ideally require emergent anatomical reduction and fixation; in elderly patients arthroplasty is preferred.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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