A 28-year-old man sustains a closed midshaft tibial fracture. After conservative management with long-leg cast, follow-up X-ray at 12 weeks shows 'elephant foot' callus with persistent fracture gap and no progression over the last 6 weeks. This pattern of non-union implies:

• A Inadequate blood supply (avascular, atrophic non-union) — requires bone grafting
• B Adequate vascularity but inadequate mechanical stability — dynamization or exchange nailing required ✓
• C Infected non-union — requires culture and antibiotic therapy
• D Normal fracture healing — 12 weeks is insufficient for tibial union

Explanation

Hypertrophic non-union (elephant foot callus = abundant, rounded callus without bridging) indicates the fracture has good blood supply and biologic potential for healing, but mechanical instability is preventing consolidation. The fracture is biologically active but mechanically unstable. Treatment is improved stability through dynamization (removing interlocking screws in nailed fractures to allow axial loading) or exchange nailing with a larger nail. No bone graft is needed since vascularity is intact. Atrophic non-union (pencil callus or no callus) indicates inadequate blood supply and requires bone grafting. Oligotrophic non-union is intermediate.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.