The effect of cemented femoral stem cross-section geometry in total hip replacement

Abstract

This paper describes the finite element analysis on the effect of stem cross-sectional geometries on stresses generated at the bone-cement and cement-stem interfaces. A simplified numerical model of the implanted femur was used, were the femur was modelled as a tubular structure and the femoral component modelled as an extruded beam. All materials were assumed isotropic and linearly elastic. The cross-sections were assumed symmetric about the medial-lateral axis. A layer of constant thickness of cement was interposed between the stem and the femoral cortex and a complex system of forces and moments generated by the hip joint contact force was applied. Maximum and minimum principal stresses were determined for twelve different cross-sectional geometries. The results show that organic type geometries provoke, comparatively, lower tensile and compression stresses. Rigid (sharp) geometries and cross-sections of low second moment of area provoke much higher interface stresses.