The Effects of Simulated Cobalt-Chromium-Molybdenum Wear Particles on a Macrophage-Lymphocyte Coculture for Evaluating Cellular Corrosion.

Background: This study examined the impact of simulated wear particles on inflammatory cell-induced corrosion (ICIC).

Methods: A 30-day macrophage-lymphocyte coculture experiment was conducted using American Society of Testing and Materials F1537 cobalt-chromium-molybdenum disks, with activators and cobalt-chromium-molybdenum particles added at none, low (1:10), medium (1:100), and high (1:500) cell-particle ratios. Supernatants collected on days 10 and 30 were analyzed for tissue necrosis factor alpha (TNFα) and interleukin 6 (IL-6) levels via enzyme-linked immunosorbent assay. Disks were examined for ICIC damage using scanning electron microscopy, and the oxygen percentage on their surfaces was analyzed with energy-dispersive X-ray spectrometry and X-ray photoelectron spectrometry.

Results: Most disks showed damage consistent with ICIC. Day 10 TNFα was higher in medium and high particle groups compared to groups without particles, while IL-6 was unexpectedly lower in those groups. On day 30, the activated medium particle group showed higher IL-6 than the nonactivated group. The energy-dispersive X-ray spectrometry showed no significant differences (P = 0.77), but X-ray photoelectron spectrometry results indicated significant differences (P < 0.0001) at high particle concentrations.

Conclusions: Overall, the data suggested that increased TNFα reflected a heightened inflammatory response, particles might temporarily inhibit IL-6 release, and there is likely a synergistic effect between activators and particles on cellular responses.