Analysis of Femoral Components of Cemented Total Hip Arthroplasty

Abstract

In cemented Total Hip Arthroplasty (THA), material chosen for femoral stem and cross section of stem itself, proved to be critical parameters for, stress distribution in the femoral components, interfacial stresses and micro movements. Titanium alloy (Ti 6 Al 4 V), when used as a material for femoral stem, recorded large displacement as compared to Chromium alloy (CoCrMo) stems. This large displacement in case of Ti 6 Al 4 V caused the stem to bend inside the cement mantle, thus destroying it. Thus, CoCrMo proved to be a better choice of material for stem, in cemented THA. Failure in THA may occur at cement-stem or cement-bone interface, thus interfacial stresses and micro movements were analysed in the present study. Comparison between trapezium and circular cross section showed that, femoral stem with trapezium cross section underwent lesser amount of sliding and debonding, at both interfaces, as compared to circular cross section. Moreover, trapezium cross section also generated lower peak stresses in femoral stem and cortical femur. The present study also took into account, effect of diameter of femur head. A 36mm diameter femur head generated lower peak stress in acetabulum liner and arrested dislocation. Metallic femur head was coupled with a liner made of cross linked polyethylene (XLPE). This material experiences almost negligible wear when compared to typical metallic and polyethylene liners, and unlike metallic liner, it is non-carcinogenic.

Risk Factors for Revision of Polished Taper-Slip Cemented Stems for Periprosthetic Femoral Fracture After Primary Total Hip Replacement

“…Compared to rectangular diaphyseal cross-section shape stems, circular shaped stems are associated with greater micromotion, inferior rotational stability, thinner cement mantles, and higher peak stresses within the cement mantle 40,41 . These factors offer a theoretical basis for our observation that ovaloid and round stems were associated higher risk of PFF revision.…”

Experimental and numerical static failure analyses of total hip replacement interfaces

“…To determine the magnitude and direction of the load and muscle forces applied to the femur, the data from the study performed by Ramaniraka et al 29 were used. The locations on the FE model of Singh and Harsha 25 were used to determine the attachment point of the muscles exerting force on the femur. The lower part of the femur was completely fixed at its distal end to prevent horizontal and vertical movement.…”

“…Senalp et al 24 researched the effects of the shape variations of the hip implant on the stress distribution under static and dynamic loads. Singh and Harsha 25 examined the effects of cylindrical and square-profiled cross-sections on stress distribution.…”