Fracture Healing and Nonunion
DNB Orthopaedics • June 2014 • Paper I • 10 Marks
Introduction
Fracture healing is a complex biological process by which a broken bone restores its continuity, mechanical strength and function. Bone is unique because healing occurs predominantly by regeneration rather than scar formation, with eventual restoration of normal lamellar architecture.
Successful fracture healing requires an appropriate interaction between biology, vascularity and mechanical stability.
Core concept
Good biology + adequate blood supply + appropriate stability = predictable fracture union.
Classification of Fracture Healing
Fracture healing is broadly classified into:
| Feature | Primary / Direct Healing | Secondary / Indirect Healing |
|---|---|---|
| Stability | Absolute stability | Relative stability |
| Interfragmentary movement | Minimal | Controlled micromotion present |
| Callus | Absent or minimal | Prominent callus formation |
| Biological mechanism | Direct osteonal remodelling | Intramembranous + endochondral ossification |
| Typical examples | Lag screw fixation, compression plating | Cast, intramedullary nail, bridge plating, external fixation |
I. Primary / Direct Fracture Healing
Primary fracture healing occurs when the fracture is anatomically reduced and maintained under absolute stability with very low interfragmentary strain.
There is little or no external callus formation.
A. Contact Healing
- Occurs when cortical ends are in near-perfect contact.
- Osteoclasts cross the fracture line forming cutting cones.
- Capillaries…