Performance Characterization of Modified ASTM F75 Alloy for Hip Implant Application

ASTM F75 is a low-carbon CoCrMo alloy which has been used as hip implant material for decades, but the ASTM F75 implants can fail when the femoral head and the acetabular cup loosen because of limited metal-on-metal bearing. Therefore, a modified version of ASTM F75 alloy which has 90 wt.% ASTM F75 plus 10 wt.% Cr is proposed. The wear and corrosion resistance of both alloys are investigated simulating the working environment of hip implants in human body. The mechanics behavior of the femoral implant under the loading condition in human body with ASTM F75 or modified ASTM F75 material used is studied with FEA simulation. The cytotoxicity (MTT) assays of the alloys are measured and compared to that of inert ceramic and cytotoxic cobalt. The experimental and simulation results show that the proposed alloy exhibits better wear and corrosion resistance than the conventional hip implant material. Both alloys behave well with respect to stress and deformation when used for the femoral implant under the loading condition in human body. These two alloys display similar cytotoxicity performance to inert ceramic.