Theory Study And Numerical Simulation Of Bone Remodeling Process Of Human Ankle After Total Ankle Replacement

Human ankle is of great importance for normal physiological function.Total ankle replacement(TAR)is used to improve ankle stability and kinematics performance.The short and mid-term performance of TAR is significant.However,due to complications and prosthesis loosening after TAR,the long term performance of TAR is not as satisfying as total hip or total knee replacement.According to bone remodeling theory,bone would change its shape and material to optimize its structure and strength when the mechanical environment around it changes.Considerable research have been done using finite element method to simulate bone remodeling process.To date,numerical simulation of the remodeling process of human ankle is limited,and the reason of prosthesis loosening is not clear.The numerical simulation of bone remodeling process after after TAR based on finite element method makes it possible to predict and evaluate long-term performance of TAR.This paper built the remodeling equation for ankle remoding based on bone remodeling theory,and designed the APDL program which simulate the remodeling process.A complete three dimensional numerical model of human foot-ankle has been created from CT data,which is later validated by comparing stress and pressure value to experimental data.Then,the remodeling process of human ankle after TAR is simulated in ANSYS.The influence of prosthesis shape and meterial is studied later.Finally,numerical simulation of osteoporosis ankle’s remodeling process is conducted.Results of this study are: Bone mass around prosthesis declined after remodeling,which may cause component loosening and failure.Stress shielding was discovered beneath prosthesis where bone resorption happened.Bone resorption occurred mainly at trabecular bone,furthermore,the modulusdensity relationship of trabecular bone has greatter impact on remodeling results than cortical bone’s modulus-density relationship.Shorter stem of tibia component effectively mitigated bone resorption,while softer prothsthesis materail was not helpful in reducing bone loss.For osteoporosis patients,bone density value decreased faster,leading to sever bone loss.This study simulated the bone remodeling process after TAR using finite element method,ascertained the reason of component loosening,and discussed the influence of prosthesis’ s shape and stiffness of remodeling results,which is of use for the optimization of prosthesis design and treatment regulation.