Metal-on-metal surface hip arthroplasties. Is annual monitoring of blood metal levels necessary?

Abstract

IntroductionBlood cobalt (Co) and chromium (Cr) ion levels have been used as surveillance tools for adverse reaction to metal debris in metal-on-metal (MoM) hip arthroplasty. The aim of our study was to present serial 7–13 year blood Co and Cr levels in a cohort of MoM total hip arthroplasties in asymptomatic patients. Material and methodsA total of 52 MoM surface total hip arthroplasties were included in this study with data collected prospectively. Annual follow-up with blood Co and Cr measurements was performed. Revision surgery was necessary for 16 patients and therefore they dropped out of the study. The metal ion levels were analysed separately in 31 asymptomatic patients. ResultsHigh Cr or Co levels were not found continuously in any of the asymptomatic patients. The median Cr in blood was maintained between 1.3 and 5.4μg/L and that of Co between 0.5 and 1.2μg/L. After 7 years, there was no significant change in Co and Cr values. ConclusionIn the medium term and in asymptomatic patients, the metallic blood levels remained unchanged; therefore, it does not seem appropriate to repeat these tests on a permanent basis in annual controls.