- Also called Aseptic necrosis or Ischaemic necrosis
- Degeneration and necrosis of osseous tissue
- Due to bone marrow pressure and ischaemia resulting from
- Fractures
- Excessive heat e.g. horn disbudding
- Neoplasia (osteosarcoma and lymphosarcoma)
- Grossly:
- Necrotic bone difficult to recognise
- Sometimes, periosteum becomes dry, dull and detaches easily
- On longitudinal section
- Yellow-white necrotic bone
- Scattered cancellous and endosteal bone
- Histologically:
- Empty lacunae or contain dead osteocytes
- Matrix remains mineralised
- Necrotic bone is slowly resorbed, sequstered or covered by new woven bone
- Persists
- May not be detected radiographically
- Associated with Calve-Legg Perthe's disease