A multiphysics stimulus for continuum mechanics bone remodeling

Bone remodelling is a complex phenomenon during which old and damage bone is removed and replaced with new one to ensure the physiological functions of the skeletal system. It involves many biological, mechanical, chemical processes at different scales. The objective of the present work is to predict the kinetics of bone density evolution by taking into account both the mechanical and the biological frameworks. In order to do so, we propose a new computational model in which the global stimulus triggering bone remodelling is the result of the contribution of a mechanical (i.e. external loads and consequent strain energy), a cellular (i.e. osteoblasts and osteoclasts activities) and a molecular (i.e. oxygen and glucose supply) stimulus. The evolution of the bone density depends on the overall behaviour of the global stimulus. More specifically, when the global stimulus is positive, bone synthesis occurs, whereas when the global stimulus is negative, resorption takes place. Although the theoretical model has been applied on a very simple two-dimensional geometry, the final results provide new insights on the influence of each stimulus on the bone remodelling process. In particular, we confirm that mechanics plays a critical role and affects the kinetics of bone reconstruction, but it highly depends on the biological events and the distribution of bone density.