Titanium-Titanium Junctions in the Knee Corrode, Generating Damage Similar to the Hip.

Background: Previous studies identified corrosion between the modular tibial components of total knee arthroplasty devices. However, gaps persist. Compared to the hip, damage modes that occur within taper junctions in the knee remain poorly understood. In this study, we investigated corrosion on total knee arthroplasty components with titanium-titanium junctions. We asked the following question: under typical in vivo cyclic loading conditions, will the same alloy damage modes from total knee arthroplasty devices resemble those documented in the hip?

Methods: A total of 50 paired titanium alloy tibial baseplates and stems were collected and semiquantitatively analyzed using Goldberg corrosion scoring. To characterize damage, a subsection of moderately and severely corroded components was sectioned and imaged using scanning electron and digital optical microscopy.

Results: Of the 100 device components, 95% showed visual evidence of corrosion. The initial contact area between the stem and bore generally occurred 3 mm from the stem taper base. Scanning electron microscopy revealed 4 damage modes, including oxide film formation, crevice corrosion, selective dissolution, and pitting.

Conclusions: Each of the damage modes identified in modular titanium-titanium tibial junctions was previously reported by total hip arthroplasty retrieval studies. Cumulatively, our results suggest that mechanically assisted crevice corrosion promoted this damage in vivo.