Corrosion of Metals During Use in Arthroplasty

Arthroplasty implants can undergo corrosion at the modularcomponents,trunnion, and hinges, owing to implant material makeup, micromotion,and interaction with body fluid. In this review, various mechanismsof corrosion in arthroplasty were explored with suggestions on meansof improvement. We identified 10 methods including pitting, crevice,mechanically assisted crevice corrosion, fretting, fretting initiatedcrevice corrosion, mechanically assisted taper corrosion, galvaniccorrosion, stress/tension, fatigue corrosion, and inflammatory cellinduced corrosion. The position of implants on the galvanic series,and their ability to maintain passivation contribute to their longevityin service. Due to the relative motion of arthroplastic components,bio-tribocorrosion may disrupt passive oxide films, and pitting isinitiated at interfaces. Thus, corrosion in arthroplasty as an electrochemicalphenomenon mainly starts on one spot and progresses in 3 steps: (1)the oxidative dissolution of metal from implant surfaces into theaqueous active environment, releasing cations, (2) the attractionof electrons to the opposite charge created at another point of theimplant surface, producing current flow, and (3) the formation ofoxides of metal and metal hydroxides deposited as rust at the surfaceof the implant. Recent innovations in material manufacturing continueto improve the efficiency of arthroplasty; however, the componentparts remain susceptible to bio-tribocorrosion. Thus, a complete eradicationof corrosion in arthroplasty would require futuristic materials withimprovement in recent materials and designs, derived from knowledgeof existing retrieved implants, and strategies to provide overallsurface finishes that protect against bio-tribocorrosion.