Bone healing

An overview of the fracture healing in humans including factors affecting it and possible complications

1. BONE HEALING
Dr BASSEY, A E
ORTHOPAEDICS & TRAUMA
UATH, ABUJA

2. OUTLINE
•Introduction
•Types of bone healing
•Stages of bone healing
•Regulation of bone healing
•Factors affecting bone healing
•Assessment
•Complications
•Current trends
•Conclusion

3. Introduction
•Bone healing refers to complex and sequential
events that occur to restore injured bone to pre-
injury state
•Bone injury remains a constant counterpart to
human existence, we are able to cope with this
due to bone healing. The surgeon must therefore
have adequate understanding of its processes,
influencing factors and complications in order to
achieve optimum outcome

4. Types of bone healing
•Healing by callus formation (indirect,
secondary)
•Healing by direct union (primary)

5. Stages of bone healing
•Healing by callus formation
–Haematoma formation
•Occurs immediately
–Inflammation and cellular proliferation
•8hrs to 1-2weeks
•Migration of inflammatory cells (macrophages,
neutrophils, platelets)
•Elaboration of cytokines, growth factors, other
mediators
•Proliferation and differentiation of mesenchymal stem
cells, migration of fibroblasts and osteoclasts
•neovascularization

6. Stages of bone healing
•Healing by callus formation
–Callus formation
•2-3wks to 4-8wks
•Osteoclasts mop up dead bone
•Collagen matrix formation
•Osteoid deposition and mineralisation
•Formation of woven bone
–Consolidation
•Weeks to 2-3mnths
•Lamellar bone formation
•Remaining gaps filled by lamellar bone

7. Stages of bone healing
•Healing by callus formation
–Remodelling
•2mnths to years
•Guided by stress exposure
•Osteoclasts are responsible
•Healing by direct union
–Occurs in fractures where ends are compressed,
with intervening space <500microns
–No callus formation
–Gap healing – occurs if space is 200-500microns
–Contact healing – occurs if space is <200microns

8. HAEMATOMA INFLAMMATION CALLUS CONSOLIDATION REMODELLING

10. Regulation of fracture healing
•Local factors
–TGF-B
–PDGF
–FGF
–IGF
–VEGF
–BMP
–Cytokines
•Systemic factors
–Hormones

11. Regulation of fracture healing
•TGF-B
–Promotes proliferatn & diff of stem cells
–Stimulates collagen synthesis
•PDGF
–Stimulates T1 collagen synth by osteoblast
–Stimulates osteoclast resorption
•FGF
–Stimulates fibroblast proliferation
–Stimulates angiogenesis
•VEGF
–Stimulates angiogenesis

12. Regulation of fracture healing
•IGF
–Stimulates bone collagen & matrix synthesis
–Inhibits bone collagen degradation
•BMP
–Osteoinductive
–Stimulates diff of osteoprogenitors to osteoblasts
•Cytokines
–IL-1,6 stimulate bone resorption
–Chemotaxis and regulation of inflammatory cells

13. Regulation of fracture healing
•Systemic factors
–Growth hormone – acts via IGF
–Thyroid hormones – increase bone resorption
–Oestrogen – minimises bone resorption

14. Factors influencing bone healing
•Local
–Type of bone
–# pattern
–# site
–Soft tissue devitalisation
–Soft tissue interposition
–Blood supply
–Infection
–Irradiation

15. Factors influencing bone healing
•Systemic
–Malnutrition
–DM
–Drugs – NSAIDs, steroids, cytotoxics
–Tobacco use
–Thyroid disorders
–Vitamin deficiency
–CNS trauma
–HIV

16. Assessment of fracture healing
•Clinical
•Radiological

17. Complications
•Malunion
•Delayed union
•Non-union
•Infection
•Post-traumatic arthritis
•Growth abnormalities

18. Current trends
•rBMP
–Delivered locally at 10-1000x natural expression
–Enhance # healing
–Decrease infection in GA IIIa & b #s
–Useful in recalcitrant non-unions
•Pulsed electromagnetic field (PEMF)
–Used in treatment of nonunions
•Low-intensity pulsed ultrasound (LIPUS)
–Increases gene expression, enhances blood flow,
enhances remodelling
–Reverses anti-angiogenic effect of nicotine

19. Conclusion
•Despite major advancement in understanding
of bone healing, problems/complications still
continue to arise.
•More research is needed in this all-important
area if these problems are to be satisfactorily
prevented or overcome

20. Thank
you

21. References
•Apley’s system of orthopaedics and fractures,
9
th
Ed, pp689 – 692
•http://www.slideshare.net/hardikpawar1/fracture-healing
•http://www.orthobullets.com/basic-science/9009/fracture-healing
•http://www.hughston.com/hha/a.fracture.ht
m