MECHANICAL FACTORS IN BONE-GROWTH AND DEVELOPMENT

Mechanobiologic factors strongly influence skeletal ossification and r egulate changes in bone geometry and apparent density during ontogeny. We have developed computer models that implement a simple mathematica l rule relating cyclic tissue stresses to bone apposition and resorpti on. Beginning at the fetal stages of the femoral anlage, these models successfully predict the appositional bone growth and modeling observe d in the development of the diaphyseal cross section. The same basic m echanobiologic rule can also predict the architectural construction of the proximal cancellous bone formed in regions of endochondral ossifi cation. Geometry and density changes in adult diaphyseal and cancellou s bone as a result of changes in physical activity can be simulated by invoking the same rule used during development. Future clinical and e xperimental work is needed to provide more quantitative data for mecha nobiologic rules and elucidate the interactions between chemical and m echanical factors influencing bone biology.