In Cierny–Mader classification of osteomyelitis, a Stage III (localised) infection differs from Stage IV (diffuse) because:
- A Stage III affects only cancellous bone; Stage IV involves cortical bone
- B Stage III is haematogenous; Stage IV is always post-traumatic
- C Stage III has well-defined, stable bone; Stage IV has through-and-through instability requiring reconstruction for cure ✓
- D Stage III involves a single pathogen; Stage IV is always polymicrobial
Correct answer: C. Stage III has well-defined, stable bone; Stage IV has through-and-through instability requiring reconstruction for cure
Explanation
In the Cierny–Mader staging, anatomical Type III (localised) means the cortical or cancellous sequestrum is well demarcated and can be excised without compromising skeletal stability; Type IV (diffuse) implies through-and-through disease requiring segmental resection, which destabilises the bone and mandates reconstructive procedures (bone transport, vascularised fibular graft, or induced membrane technique). The host classification (A, B, C) is layered on top. Type IV cannot be cured by debridement alone because stability cannot be maintained.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
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