Key terms
Glossary of key terms related to bone graft
Osteogenesis
Refers to all physiological processes contributing to bone growth, bone remodelling and bone damage repair. It is a process with varying pace in a continuum from the foetus to the elderly
Osteoconduction
Refers to a set of processes allowing cellular (osteocompetent cells), vascular and osteoinductive components from the recipient bone bed of the graft to reach the bone area to be repaired. In practice, a primary invasion of the graft by common fibrosis provides the necessary components for osteogenesis, which occurs at a later stage. The graft must therefore have sufficient porosity, free of any organic debris. In the absence of osteoconduction, the integration of the graft will only occur through peripheral bone remodelling and will obviously be much longer than with an osteoconductive product.
Osteoinduction
Refers to a process consisting of a high stimulation of osteogenesis, secondary to bone lesion or fracture, through the release of bone growth factors and the transformation of undifferentiated cells present in the bone marrow into osteoclasts and osteoblasts. A bone graft will undergo intense bone remodelling when its osteoconductive properties are sufficient enough to allow osteoinduction processes — activated in the living recipient bone— to “express themselves”.
Collagen
Refers to fibrous protein organised into parallel bundles of fibrils, with regular transverse bands (640 nm in width) under microscopy. These alternating light and dark bands are characteristic of collagen in its natural organisation. Bone collagen is type I collagen.
Hydroxyapatite
Refers to tricalcium phosphate in the form of apatite (specific crystal structure) of approximate formula 3(PO4)2Ca3,Ca(OH)2. It forms very small particles, aligned along the collagen fibres.
Trabecular (or cancellous) bone
Located in the epiphyses and metaphysis of long bones, and in flat bones, it plays roles in mechanical support and hematopoiesis. It has a structure consisting of anastomosed trabeculae (macroporosity) filled with blood vessels and marrow, surrounded by lamellar bone substance
Cortical (or compact) bone
Refers to an arrangement of basic units (osteons) surrounding the Haversian canals. The bone lamellae are more dense as compared to those of cancellous bone