Increase in free radicals on UHMWPE hip prostheses components due to inflamed synovial cell products

Oxidative degradation of artificial UHMWPE joint implants caused by gamma-r ay sterilization is thought to be responsible for the production of wear de bris resulting in adverse tissue responses. On the other hand, it is well k nown that inflammation is associated with generation, by inflammatory cells , of free radicals (H2O2 and NO) and destructive proteolytic enzymes (colla genases), which creates a strong oxidative environment. We hypothesized tha t when an UHMWPE implantation was performed in an inflammatory joint enviro nment, the oxidative substances produced by inflamed synoviocytes could inc rease oxidative degradation of the polyethylene insert. We measured the amo unt of free radicals on conventional and on Duration(TM)-treated polyethyle ne samples by the electron spin resonance (ESR) technique before and after exposure of the samples to (1) inflamed synovial cell cultures; (2) normal synovial cell cultures; and (3) medium alone. We observed an increase in th e number of free radicals on polyethylene samples after their immersion in cell cultures. Furthermore, it was observed that the increase of free radic als on polyethylene correlated with the degree of inflammation of synovial cells in culture. (C) 2001 John Wiley & Sons, Inc.