Concordance between laboratories in metal ion testing in patients with metal-on-metal hip implants

Abstract

RESEARCH • RECHERCHE Concordance between laboratories in metal ion testing in patients with metal-on-metal hip implantsBackground: Testing of whole blood or serum metal ion levels has become an important part of assessing and monitoring the performance of metal-on-metal bearings, both in hip resurfacing arthroplasty and in total hip replacement. The aim of this study was to determine the concordance between 2 laboratories testing cobalt and chromium ion levels in patients with metal-on-metal bearings.Methods: Serum and whole blood samples from patients who had undergone metalon-metal resurfacing or large-diameter total hip arthroplasty were tested for cobalt and chromium ions in laboratory A (a recognized laboratory) and laboratory B (tasked with testing clinical specimens). Laboratory A performed cobalt and chromium testing on whole blood, and laboratory B performed cobalt testing on whole blood and chromium testing on serum. Results:Samples from 104 patients were tested. Laboratory B reported lower whole blood cobalt levels than laboratory A. Furthermore, laboratory A reported that all patients had elevated whole blood cobalt ion levels compared to the normal reference values for the laboratory, whereas laboratory B reported that 46 patients (44.2%) had whole blood cobalt ion levels within the normal reference range for the laboratory. Conclusion:This comparative study highlights the importance of using a single laboratory for metal ion testing, as values generated from different laboratories may not be directly comparable. With recent literature suggesting that whole blood cobalt levels as low as 1 ppb may be a predictor of adverse reactions to metal debris, accurate clinical measurement needs to be increasingly exact.

Metal Ion Release, Clinical and Radiological Outcomes in Large Diameter Metal-on-Metal Total Hip Arthroplasty at Long-Term Follow-Up

“…Additionally, all urinary metal ions levels were adjusted to creatinine to eliminate the dilution effect of spot urine samples [ 14 ]. All of the toxicological analyses were performed by an accredited toxicological laboratory because laboratories often use different techniques making comparison of metal levels of limited clinical relevance [ 16 , 73 ].…”

Potentially toxic metallic wear nanoparticles and trace metal ions release from metal-on-metal orthopedic implants in the human biological specimens: An Overview of in vivo and ex vivo clinical studies

“…Therefore, decision to revise a MoM hip arthroplasty should not rely on a simple metal ion measurement and should include patient symptoms and radiographic evidences of implant dysfunction. The findings in this study [290] and in another [291] underscore that small differences in laboratories' protocols may lead to significant differences in test results. In an effort to determine the accuracy of testing, Saini et al…”

Comparing 1-year and 10-year whole blood metal ion results following Birmingham hip resurfacing for osteoarthritis

“…This is paramount in the interpretation of results, as differences in absolute values for cobalt and chromium have been shown to exist among laboratories owing to differences in calibration between assays. 18 …”

“…This is paramount in the interpretation of results, as differences in absolute values for cobalt and chromium have been shown to exist among laboratories owing to differences in calibration between assays. 18 Only patients who completed their blood test were included in this study. Patient baseline characteristics and 1-year whole blood metal ion levels were retrospectively collected.…”