Bone grafting

From greek.doctor
  • Bone grafting/substitution/transplantation = replacing bone with something (called a bone graft)
  • As the native bone grows it will generally replace the graft material with normal bone
  • Needed in
    • Alignment correction
      • A wedge of bone graft may be inserted into a gap made by an osteotomy to correct alignment
    • Tumour surgery
      • Significant amounts of bone are removed and should be replaced
      • Tumour in diaphysis -> part of the diaphysis is removed and must be replaced
    • Revision joint replacement (replacing the previously implanted prosthesis with a new one)
    • Bone cyst removal
    • Congenital bone defects
    • Post-traumatic bone defects
  • Properties of an ideal bone graft
    • Sterility
    • Good mechanical properties
      • Loadability
      • Fixation – must be fixable by plate or screw
    • Good healing properties
      • Osteoconduction – the grafts ability to connect the resected bone surfaces of host bone
      • Osteoinduction – the grafts ability to induce host osteogenesis
      • Osteogenesis – the grafts ability to produce bone by itself
        • Some grafts contain living osteoblasts, or a protein called BMP which stimulates host osteoblasts
    • Good availability
    • The choice of graft depends on the patient
    • A modern orthopaedic department should have all different types of bone graft available
    • There is no single “best” graft or material
  • Types of grafts according to material
    • Bone grafts
      • Solid (tubular) bone grafts
        • To replace bone after tumour removal, etc.
      • Morselized bone (= bone chips)
        • To replace bone inside a bone cyst
    • Artificial grafts
      • Metal grafts
      • Bone cement grafts
  • Types of grafts according to origin
    • Autologous (from the patient)
      • Best graft
      • Osteogenesis + osteoinduction + osteoconduction
      • Patient needs an extra surgery to acquire the bone graft
      • Limited amount
    • Allogenic
      • From a human donor
        • Cadaver
        • Brain dead
        • From another patient who had bone removed as part of joint replacement, etc.
      • Osteoinduction + osteoconduction
      • Contains BMP
      • May contain transmittable diseases (hepatitis, HIV)
      • Expensive
    • Xenogenic (from another species)
      • Only used after deprotonation, so only the inorganic bone remains
      • No BMP or transmittable diseases
      • No osteoinduction or osteogenesis, only osteoconduction
      • Grafts from sea corrals
        • Sea corrals are comprised of hydroxyapatite with similar properties as human bone