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Bone graft
This document discusses bone grafts and substitutes. It covers their classifications based on source (autograft, allograft, etc.), composition (cancellous, cortical), and state. Properties like osteoconduction, osteoinduction and osteogenesis are explained. Common indications and principles of graft incorporation are provided. Finally, complications are briefly outlined. In summary, the document serves as an overview of bone grafts and substitutes, their properties and uses in orthopedic procedures.
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Bone graft
- 1. By Dr Salihi Abdulmalik NationalOrthopaedic Hospital Dala-Kano 19th February, 2021
- 2. Outline • Introduction • Classifications •Properties of bone graft • Indications • Graft incorporation • Principles • Bone graft substitute • Complications • Conclusion
- 3. Introduction • Bone graft/substitutecan be defined as any material that alone or in combination with other materials promotes bone healing by providing osteogenic, osteoinduction and osteoconductive activity to the local site • BG is among the most commonly transplanted tissue in the body
- 4. Based onvascularity ◦ Vascularised Theoretically the ideal graft Microsurgical skills needed Sources; Iliac crest with one of the circumference a. e.g PCIA Fibula with peroneal artery Ribs with posterior intercoastal artery ◦ Non-vascularised Fibular strut
- 5. Classification • Based onsource – Autograft (gold standard) – Allograft – Isograft – Xenograft – BG substitute
- 6. Autograft ◦ Noimmunogenicity ◦ No disease transmission ◦ Cheap ◦ Limited availability ◦ Donor site morbidity ◦ Increased op and anaesthetic time
- 7. Allograft ◦ Nodonor site morbidity ◦ Large amounts available ◦ Disease transmission ◦ Immunogenic ◦ Slow incorporation ◦ Bone banking
- 8. Based on composition ◦Cancellous – More rapidly incorporated – Sources – iliac crest, GT, metaphysis of proximal tibia, distal femur, distal tibia, distal radius, proximal humerus ◦ Cortical – Less biologically active – Less surface area – Less cellular matrix – Prolong time to revascularize – They may need fixation – Sources – iliac crest, fibula, ribs, anterior-medial surface of tibia
- 9. ◦ Corticocancellous – Dualfunction of providing healing and support – Sources – iliac crest and tibia plateau ◦ Osteochondral ◦ Bone marrow aspirate
- 10. Richer andmore growth factors Up to 50cc of bone graft can be harvested
- 11. Based onstate of graft ◦ Fresh Highly antigenic Limited time to check antigenicity ◦ Preserved using Ethylene oxide Ionizing radiation Freezing (-70 degree) Freeze drying Demineralization
- 12. Osteoconduction ◦ Providescaffold/matrix for which new bone will be laid down Osteoinduction ◦ Provide growth factors that encourage differentiation of messenchymal cells into osteoblast Osteogenic ◦ Presence of cells that related to bone formation such as primitive messenchymal cells, osteoblast and osteocytes
- 13. Augment fracturehealing e.g non union Fill defect e.g following cyst or tumour excision Arthrodesis To replace a bone/disc Establish continuity of long bone e.g fibula strut
- 14. Aid screwfixation in osteoporotic bone Help establish union in pseudoarthrosis Provide joint block to limit joint motion (arthroereisis) Treatment of bone gap e.g Masquelet technique
- 15. Metabolic bonediseases Presence of infection in Allograft
- 16. Autograft undergonecrosis Viable surface cells on the graft stimulate inflammatory response Fibrovascular stroma formed Blood vessels and osteoprogenitor cells pass from recipient bone to graft Remaining viable cells stimulate osteoprogenitor cells which differentiate to osteoblast (osteoinduction)
- 17. Graft alsoprovide scaffold for new bone (osteoconduction) New bone formed replaced graft (creeping substitution) Cancellous bone incorporate more quickly and complete Vascularised graft remain viable
- 18. Cancellous ◦ Faster ◦Analogous to fracture healing ◦ Creeping substitution Cortical ◦ Slower inflammatory process ◦ Osteoclastic activity precede osteoblastic bone formation ◦ Loss of mechanical strength first 3-6 months, returns over 1-2 years
- 19. Entire graftnot incorporated No remodelling
- 20. Inflammation; chemotaxisstimulated by necrotic debris Osteoblast differentiation from precursors Osteoinduction; osteoblast and osteoclast Osteoconduction Remodelling process continues for years
- 21. Local (+v) ◦Large surface area ◦ Good vascular supply ◦ Growth factors; BMP, VEGF, PDGF ◦ Mechanical loading ◦ Mechanical stability
- 22. Local (-ve) ◦Denervation ◦ Infection ◦ Radiation ◦ Local bone disease ◦ Foreign body ◦ Mechanical instabilty
- 23. Systemic (+ve) ◦Growth hormone ◦ Insulin ◦ PTH ◦ Thyroid hormone ◦ Vitamins A and D
- 24. Systemic (-ve) ◦DM ◦ Steroid ◦ Chemo ◦ Malnutrition ◦ NSAIDS ◦ Metabolic bone disease ◦ Sepsis ◦ Smoking
- 25. Pre op ◦Indications met ◦ Remove/reduce –ve factors ◦ Informed consent
- 26. Intra op ◦GA/SAB, positioning, exposure ◦ Fresh instruments/gloves for op and donor site ◦ Cortical window ◦ Stay posterior to ASIS ◦ Don’t go beyond 8cm lateral to PSIS In children posterior iliac crest is a good donor site ◦ Dissect directly down to the bone
- 27. ◦ Expose onlyarea needed ◦ Take only amount needed ◦ Cancellous BG; morselisation increases the surface area of the graft and also exposes the bone cells ◦ Harvested bone graft should be kept moist ◦ Achieve haemostasis
- 28. Post op ◦Monitor post op bleeding ◦ Analgesia ◦ Protect donor site ◦ Change dressing as frequent as necessary
- 29. Dispensable? ◦ Disposeand harvest another graft Indispensable? ◦ Rinse with normal saline ◦ Place in antibiotics for 10-15 minutes ◦ Make use of the graft ◦ Inform patient post op
- 30. Bleeding Nerveinjury Vascular injury Pathological fracture Hernia Urethral injury ASIS avulsion Pelvic instability
- 31. BMP ◦ Originallyextracted from allogenic BG ◦ BMP 2 and 7 are commercially produced ◦ Need carriers Allograft Demineralized bone matrix Collagen Bone cement
- 32. Calcium based Calcium phosphate Calcium hydroxyapetite Calcium sulphate ◦ Primarily osteoconductive ◦ Calcium hydroxyapetite and phosphate are used to fill metaphyseal defects Tibial plateau Calcaneum Radial fracture ◦ No sufficient strength
- 33. ◦ Absorbed Calciumsulphate 6-9 weeks Calcium phosphate 6-9 months Calcium hydroxyapetite several years
- 34. Bone graftand bone graft substitute play important role in orthopaedics; arthroplasty, limb reconstruction, spine etc