Dissemination of metals from a failed patellar component made of titanium-base alloy

Complications related to the patella are the most common problems in total knee arthroplasty and major reasons for revision surgery. Among patellofemoral problems, metal-to-metal contact between patellar and femoral components is the worst. We measured levels of titanium, aluminum, and vanadium in serum and urine samples and compared these measures from cases in which metal-to-metal contact of the patellar component occurred with those in cases in which only polyethylene wear occurred. Serum levels of the metals in cases with metal-to-metal contact were over 10 times higher than those in cases without metal-to-metal contact. This suggests that different ranges of serum metal ion levels could eventually be correlated with a variety of mechanisms of patellar failure. Therefore, cases with metal-to-metal contact should be distinguished from cases without metal-to-metal contact. These should not be considered as a single group in patellar component failure.