Bio-mechanical Study On The Artificial Hip Prosthesis System

The total hip arthroplasty (THA) which is widely used in the field of surgical osteoplasty is an efficacious method of curing hip diseases and recuperating the walking function of patients. Biomechanical analysis to the THA system can make for realizing its mechanical properties and giving help to the clinical selection and individual design of prosthesis. In this study, bio-mechanical properties of artificial hip prosthesis and femur-implant system after THA were analyzed using 3D finite element method, including the stress of acetabular cup liner, fretting wear on the head-neck interface of prosthesis and the stress on femur-implant system.The results of acetabular component contact analysis to different implant design parameters, such as head diameter, thickness of UHMWPE liner and head material, demonstrated that the stress on cup liner decreased with head diameter increased; cup thickness and head material had very weak effect on the stress. In a gait cycle, the maximal stress appears on push-off phase and the stress level during stance-phase is obviously higher than swing-phase, and high stresses mostly centralize on location of the 1/4 top-back of the cup.Head-neck contact model was also analyzed in order to evaluate the fretting wear performance of the interface of components. It was indicated that the contact stress and relative displacement of the head-neck interface decreased as the head diameter increased and these two values also decreased as the taper angle increased in small angle range, but the contact stress had an obvious increase when the angle was very large. In this study, the assembly of Alumina head and Ti6Al4V neck produced the smallest contact stress and relative displacement, which would alleviate the fretting wear most.The stress results on the femur and implant after THA revealed that the femoral stress was significant smaller than before and the maximal stress value appeared at location of the 1/3 distal of femur; high stress centralized on the neck of implant. It was seen that the length of the stem had little effect on the stress of femur and implant, but as neck-stem angle increased, the femur stress increased slightly and the neck stress decreased obviously. The prosthesis made of Ti alloy produces higher stress on the femur lateral of interface and lower stress on the implant than that made of Co-Cr...