Factors Influencing Fracture Healing and Bone Graft Substitutes
DNB Orthopaedics • October 2023 • Paper I • Question 5 • 10 Marks [4+6]
Introduction
Fracture healing is a complex biological process requiring an adequate cellular response, vascularity, mechanical environment and extracellular matrix. Failure of any of these components may result in delayed union or nonunion.
Bone grafts and bone-graft substitutes are used to enhance healing by providing one or more of the following properties: osteogenesis, osteoinduction and osteoconduction.
The ideal graft material would be: osteogenic + osteoinductive + osteoconductive + mechanically competent + non-immunogenic + readily available.
Fundamental Concepts
| Property | Definition | Example |
|---|---|---|
| Osteogenesis | Formation of new bone by living osteogenic cells present in graft | Autologous cancellous bone / bone marrow |
| Osteoinduction | Recruitment and differentiation of progenitor cells into osteoblasts | BMPs, DBM |
| Osteoconduction | Scaffold allowing vascular and cellular ingrowth | Calcium phosphates, hydroxyapatite |
A. Factors Influencing Fracture Healing [4 Marks]
Factors may be classified into:
1. Patient / Systemic Factors
2. Local Biological Factors
3. Mechanical / Treatment Factors
1. Systemic / Patient Factors
| Factor | Effect on Healing |
|---|---|
| Age | Children heal faster; healing generally slows with advancing age |
| Nutrition | Protein, calcium, phosphate and vitamin deficiency may impair healing |
| Smoking / nicotine | Impairs… |