Orthonotes
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Autograft is gold standard: osteogenic + osteoinductive + osteoconductive (iliac crest). Allograft provides scaffold (osteoconductive) ± growth factors; immune & disease transmission risks minimized by processing. Substitutes: calcium phosphates (HA/TCP), calcium sulfate, bioactive glass; mainly osteoconductive. Biologics: BMP‑2/7, PRP (controversial), bone marrow aspirate concentrate. Applications: nonunion, defects, spinal fusion; match graft biology to defect needs.
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Bone grafting is a surgical procedure used to stimulate bone healing, replace missing bone, or augment bone stock in orthopaedic reconstruction. Bone grafts are widely used in fracture nonunion, spinal fusion, tumor surgery, revision arthroplasty, and reconstructive trauma procedures.
The purpose of bone grafting is to enhance the biological environment for bone healing by providing cells, growth factors, and structural scaffolding that support new bone formation. Successful graft incorporation depends on mechanical stability, vascular supply, and biological compatibility between graft and host bone.
Bone grafts function through three fundamental biological mechanisms that support bone regeneration.
| Mechanism | Description | Clinical Example |
|---|---|---|
| Osteogenesis | Formation of bone by living osteoblasts present in the graft | Autogenous cancellous graft |
| Osteoinduction | Stimulation of stem cells to differentiate into osteoblasts | Bone morphogenetic proteins |
| Osteoconduction | Providing a scaffold for new bone growth | Allografts and synthetic substitutes |
Autografts possess all three biological properties. Allografts and synthetic substitutes primarily provide osteoconduction, although some processed grafts may also provide limited osteoinductive activity.
Bone grafts are classified according to their biological source.
| Type | Source | Key Advantages | Limitations |
|---|---|---|---|
| Autograft | Same patient | Best biological properties | Limited quantity |
| Allograft | Human donor | Large supply | Risk of disease transmission |
| Xenograft | Different species | Abundant supply | Immune reaction risk |
| Synthetic substitute | Artificial material | No donor morbidity | Limited biological activity |
Autogenous bone grafts are harvested from the same patient and remain the gold standard in bone grafting procedures. Because they contain living osteoblasts and growth factors, they possess the full spectrum of biological activity required for bone regeneration.
The iliac crest is the most commonly used donor site because it provides a large volume of cancellous bone with high osteogenic potential.
Allografts are obtained from cadaveric donors and processed in bone banks. They provide structural support and an osteoconductive scaffold but lack viable osteogenic cells.
Demineralized bone matrix contains bone morphogenetic proteins that may provide osteoinductive properties.
Synthetic substitutes are artificial materials designed to mimic the structural properties of bone. These materials primarily function as osteoconductive scaffolds.
| Material | Characteristics |
|---|---|
| Hydroxyapatite | High osteoconductivity |
| Tricalcium phosphate | Biodegradable scaffold |
| Calcium sulfate | Rapid resorption |
Bone morphogenetic proteins are growth factors belonging to the transforming growth factor beta family. They stimulate mesenchymal stem cells to differentiate into osteoblasts and promote new bone formation.
These proteins are used clinically in selected spinal fusion procedures and treatment of nonunions.
The Masquelet technique is a two-stage reconstructive procedure used for management of large bone defects.
The induced membrane produces growth factors that enhance graft incorporation and vascularization.
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