Postmortem Retrieval Analysis of Metallosis and Periprosthetic Tissue Metal Concentrations in Total Knee Arthroplasty

The purpose of this study is to determine the preferred sampling location for tissue analysis in total knee arthroplasty (TKA) and to evaluate metal concentrations, inflammatory cytokines, component damage, and tissue metallosis.

Twenty TKA systems were collected at necropsy along with tissue samples from 5 distinct locations. Inductively coupled plasma mass spectrometry (ICP-MS) analysis was performed to determine cobalt (Co), chromium (Cr), and titanium (Ti) concentrations. Synovial fluid cytokine analysis was preformed using a Magnetic Luminex Screening Assay. Femoral components were assesed for damage and tissues were visually scored for metallosis.

The median metal concentrations were 16 ppb for Co, 46 ppb for Cr, and 9.8 ppb for Ti. There was no association between the tissue collection site and the metal concentration for Co ( P = .979), Cr ( P = .712), or Ti ( P = .854). Twelve of 20 of the necropsy-retrieved TKAs had metallosis, but there was no correlation between Co ( P = .48), Cr ( P = .89), or Ti ( P = .60) concentration and metallosis. Increased Co was associated with decreased tumor necrosis factor alpha (ρ = −0.56, P = .01) and interleukin 1 beta (ρ = −0.48, P = .03). Increased Cr was associated with decreased tumor necrosis factor alpha (ρ= −0.47, P = .03), interleukin 6 (ρ= −0.43, P = .04), and macrophage inflammatory protein 3 alpha (ρ= −0.47, P = .03).

We observed elevated Co, Cr, and Ti concentrations in tissue from necropsy-retrieved TKA. Our findings did not support the hypothesis that tissue metal concentrations were associated with inflammatory cytokines. The results of this research will be useful for the design of future prospective studies.