Convergence Criteria For Topology Optimization Of Titanium Alloy Prosthesis And Its Application

Currently,implant prosthesis is the fastest and most effective way to treat irreparable bone damage.In the past,artificial bone was mostly titanium alloy material because the industrial technology and clinical level were limited.Stress shielding effect is one of the main reasons for the aseptic loosening of artificial joint.In addition,the solid titanium alloy prosthesis has a poor experience and short life after being implanted in the human body.A topology optimization convergence criterion for titanium alloy was established for the topological optimization of implants.The elastic modulus of the prosthesis was matched with the proximal skeleton of the prosthesis,which reduced the stress shielding of the proximal bone.The convergence criterion is verified by topological optimization on the upper part of the femur.The normal walking process is decomposed into three typical moments,the early toe starts to leave the ground,the middle leg is supported,and the heel lands on the heel.The topological optimization method is used to redistribute the prosthesis materials under the maximum load dynamics environment.The bone marrow cavity was formed in the femoral model after optimization.The optimized structure was observed along axial and radial profiles,and compared with the bone marrow cavity of the femur,the results showed that the hollow structure of the prosthesis was similar to that of the actual bone marrow cavity.The elastic modulus of the macroscopic section of the region was optimized every 5mm,and the total macroscopic elastic modulus of the prosthesis was reduced to 1/5 ~ 1/2 of the entity.Compared with the elastic modulus of the upper part of the human femur by the relationship between the distance of the femur and the elastic modulus of the section.The results show that the macroscopic elastic modulus of the optimization model is well matched with the elastic modulus of the human femur,and the convergence criterion is reliable.It can be used to optimize the structure of titanium alloy implant prosthesis to reduce the stress shielding of the bone.The ankle is one of the joints that is most likely to cause serious injury to the bones,and non-self-repair talus fracture is particularly prominent.Full range bone prosthesis replacement can greatly recover the motor dysfunction caused by bone injury.First,using reverse engineering to reconstruct the ankle joint model.Secondly,by using the convergence criterion of titanium alloy prosthesis to optimize the model of ankle joint in the optimization software and obtain the hollow structure of the prosthesis.Thirdly,the software magics was used to observe the internal structure of the optimized distance bone prosthesis.The macroscopic elastic modulus of the prosthesis was obtained by calculating the cross-sectional area of the prosthesis before and after the optimization of the tibial contact surface at 2mm.Calculation results show that the modulus of elasticity modulus was reduced to 1/5 ~ 1/2 of the entity.The result of this optimization can reduce the stress shielding effect on the proximal skeleton and optimize a reasonable titanium alloy talus prosthesis.