Samuel James Collins

Association of ultra-high-molecular-weight polyethylene wear with osteolysis, leading to late aseptic loosening, has resulted in increased interest in alternative bearing prostheses. Alternative prostheses with cobalt-chrome bearing surfaces are now used more frequently, but research is needed to determine potential long-term biological effects of cobalt-chrome wear. The biological reactivity of cobalt-chrome particles may alter due to passivation and the storage of these particles in the laboratory; therefore, before any research can be carried out with these particles, an optimum storage protocol must be developed. This study aimed at determining any effects of the storage medium on the biological reactivity of cobalt-chrome wear. The viability of L929 cells was assessed following culture with clinically relevant cobalt-chrome particles stored in phosphate-buffered saline, in serum and dry at using condition the 3-[4, 5-Dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide assay. Storage of these cobalt-chrome nanoparticles (100 and 50 μm³ cell⁻¹) in serum resulted in a significantly greater reduction in cell viability compared with dry stored particles at the same dose, indicating that the storage of cobalt-chrome wear influences the biological reactivity of the particles. Therefore, it is suggested that studies investigating effects of cobalt-chrome wear particles should store them in serum prior to use in laboratory studies, these particles display the highest level of cytotoxicity and are how the particles are presented in vivo.