A Three-dimensional Orthotropic Adaptation Algorithm for Femur Remodeling

The density distribution and internal structure of bone relate to exterior loads on it. To study the remodeling process of trabecular bone, an adaptation algorithm with direction determination and stiffness modification was developed and applied to a 3D femoral finite element model. Material axes of every trabecular element were rotated to three principal stress directions determined from load cases in local coordinate system, then elastic and shear moduli were changed according to mechanical stimulus respectively. The calculation results have shown that the distribution of bone density and anisotropy degree corresponded well to the morphology of real femur, and trabeculae direction aligned with the known trabecular pattern. This orthotropic adaptation algorithm can simulate the remodeling process of femoral trabecular bone accurately.