Finite Element Analysis of Stress Distribution of Cemented Stem After Total Hip Replacement

A three dimensional finite element model was constructed based on the cemented total hip arthroplasty to study the stress magnitude and stress distribution of the cemented intramedullary stem. The von Mises stresses of the artificial femoral stem in the different cemented conditions and loading conditions simulated in vivo were calculated and analyzed using ABAQUS finite element software. The results of this study show that the von Mises stress values of the artificial femoral stem are significantly affected by the cemented conditions and loading conditions of the stem. When the entire stem was cemented perfectly, the peak stress and the stress regions appeared in the neck of the stem and the stress distribution curves varied slowly with the loading angle alpha increasing even if the load P simulated the hip joint force reached to 6 W or 1 W, in which W is the human weight. While when the lower two thirds stem was cemented perfectly the peak stress changed considerably both in magnitude and in distribution, the stress value increased greatly and the stress regions was found to shift toward the lateral aspect of the upper one third part of the stem, the stress distribution curves became clearly steep with the loading angle alpha increasing. Especially, when only the lower one third stem was cemented perfectly the peak stress became much higher, increased 6 times to 7 times compared to the peak stress of the entire stem cemented perfectly, the peak stress occurred in the position on the lateral aspect which located to the one third from the stem tip, and the stress distribution curves rose sharply with the loading angle alpha increasing even if the load P reached only from 2 W to 4 W. If alpha>35deg, load Pges4 W and l=L/3 (the lower one third stem cemented perfectly) the von Mises stress values may exceed the strength limit of the stem material. These analysis results provide helpful reference data for the design, manufacture and clinic practice of artificial hip- joint, as well as for the patients.