Evaluation of couple/crevice corrosion by prosthetic alloys under in vivo conditions.

Alloys of cast Co-Cr-Mo, wrought Co-Cr-W, wrought, Co-Ni-Cr-Mo(MP35N), Ti-60% Al-4% V, and graphite were incorporated in specimens which simulated both a couple and a crevice corrosion condition. These specimens were implanted in a dog for 30 months. Post-sacrifice examination showed no substantial evidence of corrosion activity on the surfaces of the metals except for a tarnish film on the titanium alloy specimens. The presence of the tarnish film is taken as more evidence of corrosion activity and this correlated with a thicker average fibrous membrane, cellular activity in and near the fibrous membrane, and some increased vascularity. These must be regarded as preliminary observations.