Mechanical Effect of the Articulating Materials to the Proximal Femur and the Femoral Stem in Total Hip Arthroplasty

초록

Purpose : Using the finite element analysis, the authors analyze the effect of the articulating material properties of the total hip arthroplasty to stress and micromotion of proximal femur and femoral stem. Materials and Methods : The head(28mm) and acetabular components(outer diameter= 54mm, liner thickness=11.4mm) were considered as ceramic on ceramic, ceramic on polyethylene, metal on metal, metal on polyethylene and metal on metal-polyethylene. The femur was modeled with different friction coefficients according to the different contact portion of the femoral stem which was modeled after Omnifit HA #9(Osteonics Co., Allendale, NJ, USA). Non-linear contact analysis was proceeded in human with body weight of 70 Kg at one leg standing and stair climbing. Results : The maximal yield strength was always higher in hard-hard coupling and the site of maximal yield strength was represented at the contact point of articulation. In stair climbing, the site of maximal yield strength was represented at the same site in the hard-hard coupling but at the lateral aspect of the neck in hard-soft coupling.. There were no changes in the patterns of stress distribution but the micro-motions was up to the limit of bone ingrowth in hard-hard couplings. Conclusion : The maximal yield strength and the micro-motions revealed different values according to articulating materials. These findings were considered valuable informations to producing and lengthening the life span of the total hip prosthesis but requiring the following experimental and clinical study.