Titanium alloy (Ti6Al4V (ASTM F-136)) is typically used for modular hip implant stems. This highly corrosion resistant alloy forms passive surface oxide films spontaneously. However, with modular designs, micro-motion may occur at the taper junctions during mechanical loading. Complex physical/chemical reactions take place which may result in pitting and crevice corrosion. Crevices between the taper junctions may allow the body fluids to enter and remain stagnant. These conditions make the modular tapers susceptible to fatigue and mechanically assisted crevice corrosion. When two or more surfaces are in close proximity, it leads to the creation of a locally blocked region in which enhanced dissolution may occur. The in vivo degradation of metal alloy implants compromises the structural integrity. Stochastic modeling of crevice corrosion is performed based on the mechanism behind the phenomenon. Sensitivity analysis is performed, and conclusions drawn.
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