Corrosion at the interface of cobalt-alloy heads on titanium-alloy stems.

The combination of a cobalt-alloy head on a titanium-alloy femoral hip stem is widely accepted for press-fit and biologic fixation applications. Examination of 30 components retrieved at periods of 0.5 to 66.9 months for histologic examination of tissue ingrowth revealed that 56.6% of the tapered connections between head and stem showed evidence of crevice corrosion leading to concerns of metal ion release and the potential failure of head to stem fixation.