A Novel 3D Strain-Adaptive Continuum Orthotropic Bone Remodelling Algorithm: Prediction of Bone Architecture in the Femur

Prediction of trabecular architectural arrangement and bone property distribution is fundamental in understanding the underlying mechanics of fractures. An iterative strain-adaptive bone remodelling algorithm that predicts orthotropic elastic property distribution in bone was developed and applied to a three-dimensional (3D) model of the proximal femur. Bone was modelled as a continuum matrix with local orthotropic material properties. In each iterative step, local material orientations were updated in order to match the principal stress directions and local properties modified according to the associated normal strains. The model was run iteratively until convergence was achieved. Results showed that the proposed algorithm could predict known trabecular features and architecture. Directionality of these trabecular structures matched previously observed primary and secondary compressive and tensile groups in the proximal femur. Currently, more physiologically accurate models of the whole femur are being developed, with inclusion of free boundary conditions and multiple load cases. It is believed that this approach can be a valuable tool in assessing directionality of bone structure and corresponding orthotropic material property distribution. It can have a direct impact on the understanding of fracture mechanics and development of impact protection devices for vehicle collisions or high risk roles, amongst other applications.