Knee arthroplasty failure is associated with significant systemic multimetal exposure

This study investigated whether patients scheduled for revision total knee arthroplasty (TKA) are systemically exposed to arthroplasty metals, and whether systemic metal levels in these patients differ depending on the implants' levels of constraint.

Whole blood samples were collected from patients scheduled for revision TKA (implant group, n = 51) and from arthroplasty-naïve controls (n = 53). Using inductively coupled plasma mass spectrometry, all TKA-relevant metals were quantified. Differences in systemic metal levels in patients with failed unconstrained implants (n = 31) and constrained (n = 20) implants were analysed. Correlations between levels of the different arthroplasty metals were assessed, using the Mann-Whitney test, Kruskal-Wallis test with Dunn's multiple comparison test, Spearman r matrix, and linear regression with Spearman correlation as appropriate. A p < 0.05 was considered statistically significant.

Patients scheduled for revision TKA showed significantly higher systemic Co (p < 0.001), Cr (p < 0.001), Mo (p = 0.039), Ti (p < 0.001), Nb (p < 0.001) and Zr (p < 0.001) levels compared with controls. Failed constrained TKA implants were associated with significantly higher levels of Co (p = 0.002), Cr (p = 0.005), Ti (p = 0.047), Nb (p = 0.023) and Zr (p = 0.046) than detected in patients with failed unconstrained TKA implant. In patients awaiting revision of a constrained implant, whole blood levels of Co and Ti (p < 0.001), as well as of Zr and Ti (p < 0.001) significantly correlated, whereas no such correlations were observed in patients with failed unconstrained TKA implant.

Patients with failed TKA are systemically exposed to arthroplasty metals. Correlation analyses suggest a link between the release of Co and Ti as well as of Zr and Ti in patients awaiting revision of a constrained TKA implant. Additional research is required to investigate the potential biological effects of TKA-related metals, and to establish clinically relevant systemic threshold levels.

Level II therapeutic study.