Characterization of metal-wear nanoparticles in pseudotumor following metal-on-metal hip resurfacing

Cobalt and chromium (Co/Cr) wear nanoparticles originating from metal-on-metal hip resurfacing (MoMHR) in pseudotumour tissue retrieved from hip revision were analysed. These particles were taken up mainly by macrophages. There they corroded in the acidic environment of the phagosomes. As Co is more soluble than Cr, it may be released inside macrophages, causing death of individual nanoparticle-overloaded macrophages and nearby fibroblasts and subsequently leached from the tissue. However, the consequence of the Cr remaining in tissues still requires further study.247