In vivo measurement of anodic polarization of orthopaedic implant alloys: comparative study of in vivo and in vitro experiments.

A new system of single piece electrodes was applied to in vivo and in vitro measurements of anodic polarization of several alloys used in orthopaedic implants. The tested surface was scrutinized with a stereomicroscope after each experiment. This confirmed pit formation and excluded the possibility of other sudden increase of anodic current such as crevice corrosion and oxidation or reduction of organic substances. The results were reproducible. Although there were certain differences between the results obtained in the two conditions, the order of corrosion resistances of alloys was consistent.