Bone grafting is essential in orthopedic surgery for fracture healing, non-union treatment, spinal fusion, joint reconstruction, tumor surgery, and infection management. Grafts function through three mechanisms: osteogenesis (living cells producing new bone), osteoinduction (signaling molecules recruiting host cells to differentiate into osteoblasts), and osteoconduction (scaffold supporting bone in-growth).
Categories include: 1) Autograft — patient's own bone (iliac crest, fibula, distal radius, intramedullary reamings) — gold standard with all three properties but limited supply and donor site morbidity (10-30% chronic pain at iliac crest); 2) Allograft — cadaveric bone (fresh-frozen, freeze-dried, demineralized bone matrix DBM) — variable osteoinductive properties, abundant supply, theoretical disease transmission risk; 3) Xenograft — animal-derived (bovine, porcine) — primarily osteoconductive scaffold; 4) Synthetic substitutes — calcium phosphate ceramics (hydroxyapatite, tricalcium phosphate), calcium sulfate, bioactive glass, polymers (PMMA, PCL), composite materials.
Modern enhancement includes growth factor application: bone morphogenetic proteins (BMP-2, BMP-7) provide potent osteoinduction approved for spinal fusion and tibial non-union; platelet-rich plasma (PRP) provides growth factors; bone marrow aspirate concentrate (BMAC) provides progenitor cells; mesenchymal stem cells in clinical investigation. Selection depends on graft requirements (structural vs cancellous), defect size, infection risk, patient factors, and cost. Combination strategies (allograft with autograft or BMP) often provide optimal outcomes for large defects or compromised biology.