A wide array of cobalt-based and titanium-based implant materials are used for orthopaedic applications. It is generally acknowledged by most biomaterial specialists that mixing of metals in the body is not a desirable situation because of possible galvanic corrosion reactions. However, complex orthopedic devices may be designed to utilize the favorable properties of various components which may include coupling cobalt and titanium biomaterials. The generation of anodic polarization (AP) corrosion curves in a physiological solution is a convenient method for estimating whether galvanic corrosion will be expected. Superimposed corrosion curves can be evaluated to determine whether further testing is warranted. The AP screening method is helpful but is not considered the final determinant regarding whether galvanic corrosion problems will be encountered.

The present study determined the galvanic corrosion susceptibility of coupled cobalt and titanium implant material coupons or implant components. All testing was performed according to ASTM G71 in Ringer’s solution at 37°C. Sample attachment methods and special sealing techniques were evaluated to avoid crevice and pitting corrosion reactions between the specimen and holder. Cobalt-base Elgiloy, MP35N, and L-605 alloys were coupled with Ti-6Al-7Nb in one series of tests. Galvanic corrosion testing was also performed with unalloyed Ti vs.Ti-6Al-Nb and unalloyed Ti vs. Ti-6Al-4V ELI for information purposes. Post-testing evaluation also included surface examination for pitting and ICP analysis of appropriate metals to identify soluble metal ion concentrations in the spent Ringer’s solution.