Individual Design And Optimization Of Artificial Joint Based On Biological And Structural Discipline

The artificial hip replacement had become a important treatment of the hip jointdisease.In our country,the imported hip prosthesis were used in most clinical operation ofhip arthroplasty.The size of imported hip prosthesis did not match chinese hip anatomycompletely,which may be easy to result in poor of postoperative effect and reduction ofthe service life.Meanwhile,there had been significant individual differences in the bodyfunction and the movement.It was difficult to meet the needs of patients through thestandardized design of joint prosthesis.Therefore,research and development on thetechnique of individualized artificial hip joint design had important important value.In view of this,the relationship between the service life of hip prosthesis and thephysical function of patients was considered,in order to set up the mathematical model ofmicro displacement of hip prosthesis. The sensitiveness of objective and influentialpercentage of each factor were obtained based on principle of sensitivity analysis.Meanwhile, the mathematical model of discrete variable optimization was established,inorder to obtain the best design parameters of human walking and prosthesis design.Firstly, In order to evaluate the influence of human body factors on stability of hipprosthesis accurately, some factors such as bone density of human body, body mass,walking step size, the height of human and the size of lifted foot were considered.Mathematical model of micro displacement of hip prosthesis was set up, applying theknowledge of human biomechanics and elasticity mechanics, with which the objective ofstability of hip prosthesis was concerned. Sensitivity curves of influence factors weredrawn in MATLAB based on principle of sensitivity analysis. Meanwhile, eachsensitivity function expression of factors was obtained through fitting the data in curves.The sensitiveness of objective and influential percentage of each factor were obtainedwith base value of five factors above. The results show that the greatest influence onstability of hip prosthesis was bone density of human body, followed by walking stepsize, body mass, the height of human and the lifted size of foot.Secondly, the relationshipbetween the service life of hip prosthesis and the physical function of patients and theactive coating of artificial hip joint was analyzed for the optimization mathematicalmodel. Mathematical model optimization in MATLAB was comprised of writingrelated.M documents.The walking step size, the size of lifted foot,the coating thicknessof hip prosthesis and the components of HA in the coating were regarded as designvariables.The ratio of the hip joint force and the human weight,the movement distance ofhip in a gait,the stress shielding rate of hip prosthesis,the bioactivity of coating,thehuman body stability and the bonding strength of coating and metal substrate werechosen as constraint function.The objective function was to reduce the wear ofbioactivity of coating every year.The best design parameters of hip prosthesis wereobtained from use of MATLAB optimization Toolbox solution.In contrast,the results wasshowed ultimately determined the best walking parameters of human and the best design parameters for hip prosthesis such as the walking step size was610mm; the lifted size offoot was13.1mm; the components of HA in the coating was77%;the coating thicknesswas0.098mm.The result of the wear of bioactivity of coating every year was7.37mm3/year.It was indicated that the optimizing model of the hip joint was41.9percentages lower than the original model.It was good to be given instruction and reference for clinical use of hip prosthesisand the technique of individualized artificial hip joint design to do the research of thispaper.