Three Dimensional Simulation of Adaptive Bone Remodelling in THR Femur

The adaptive bone remodeling phenomenon in the femur before and after prosthetic total hip joint replacement (THR) was investigated using the three dimensional finite element method. A normal hip joint model which composed of the proximal femur and the pelvic bone including femoral head and acetabular was constructed three-dimensionally by our method reported previously. The simulation model was use to determine the bone density distribution in a normal femur using the adaptive bone remodeling theory proposed by Weinans et al. It was confirmed that the bone density distribution obtained from the simulation was almost similar to the physiological distribution of mineral content of a normal human femur observed by an X-ray photograph. Subsequently, THR model was constructed by the insertion of a noncemented prosthesis of Harris Type into the normal hip joint model. The remodeling simulation of THR model showed that the bone density and the stress decreased significantly at cancellous bone around bone-stem interface. This result supports that the bone remodeling is one of the important biomechanical reason of loosening to occur in a femur with a noncemented prosthesis. In addition, the configuration effect of a collar projection at prosthesis on bone remodeling was analyzed with this model. However, the effect was not clear in this simulation.