Bone grafts Flashcards
What are the 3 major functions of bone grafts
Osteogenesis - providing osteoprogenitor cells for bone formation - formation of osteoid by osteoblasts
Osteoinduction - signaling new bone formation - stimulation of host cells to produce bone through cellular signalling/ cytokines
Osteoconduction - provision of a scaffold for new bone formation. Provides physical support for osteoprogenitor cells to attach and spaces for tissue migration
Which 3 sites can be used for autologuous cancellous bone graft harvesting
Proximal tibia (least common) - 2-5cm vertical incision in the proximodistal centre of the bone, over the palpable craniomedial region. Elevate periosteum & drill 1-2 4.5 or 5.5 cortical holes. Can connect 2 holes with a reamer to improve access. Close SQ & skin. NB stress risers in recovery
Tuber coxa - 3-5cm incision ventrocaudal TC. Reflect periosteum & drill 1-2 4.5 or 5.5 holles to insert curette. Alt is hollow drill bits or trephine burrs; latter maintains cortical plug
Sternum - 8-10cm ventral midline incision overlying 4th-6th sternebrae, centred 15cm rostral to xyphoid. Use periosteal elevator or rongeur to reflect hyaline cartilage - don’t want cartilage in the graft. Harvest graft with curette
Avoid grafts touching saline or gent - toxic to cells; store on blood soaked sponges until used (ASAP)
Grafts should be packed into defects
How is demineralised bone matrix created & what are some advantages over autologous cancellous bone grafts
Allogenic bone treated in HCl
Destroys osteocytes so avoids possible immune rx of allogenic grafts. Retains BMPs & collagen martix.
Avoids morbidity assoc w graft collection (stress risers, pneumothorax etc)
Osteoinductive at 2-10mm3 particle size (best 2-4mm3)
