Wear induces osteolysis leading to periprosthetic bone loss and TJA loosening. Inflammatory immune cells can form an aggressive interface membrane activating osteoclasts. The current study shows the effect of metal particles and ions triggering cellular responses.

Blood samples from primary and revision TJA were analysed for systemic inflammation. PBMCs were cultured on different implant materials. Cellular response was monitored by qRT-PCR.

Furthermore, cells were exposed to increasing concentrations of metal particles (10-7 and 10–8 particles/ml) and CoCl2 (50 µM and 100 µM). Cellular response was measured using WST-1 reduction, MitoSox-fluorescence and TUNEL-staining. Cobalt ion influx into osteoblasts was measured using FURA2-staining, cellular effects for HIF-1alpha and qRT-PCR.

No inflammatory parameters were detected in patients' blood from primary and revision TJA. Short inflammatory reaction of their PBMCs was observed in in vitro culture on ceramic implants, whereas there was no such reaction to other tested implant martials. In MM6 and Jurkat cells only metal ions induced oxidative stress but did not significantly reduce cell viability. An increase in HIF1-alpha was observed in tissue containing large amounts of metal wear in comparison to plastic wear containing tissues and OA synovial tissue without wear particles. Cobalt ions were stored by osteoblasts via a calcium channel inducing hypoxia. This effect could be blocked using a TRPM blocking agent.

Ceramic induces a short inflammatory response that may induce periprosthetic inflammation. Ionic Cobalt induces oxidative stress and hypoxia. Ionic metal exerts a more intense reaction on cells than particles.