IN-VITRO HUMAN MONOCYTE RESPONSE TO WEAR PARTICLES OF TITANIUM-ALLOY CONTAINING VANADIUM OR NIOBIUM

Our aim was to determine whether in vitro studies would detect differe nces in the cellular response to wear particles of two titanium alloys commonly used in the manufacture of joint replacement prostheses. Par ticles were of the order of 1 mu m in diameter representative of those found adjacent to failed prostheses. Exposure of human monocytes to t itanium 6-aluminium 4- vanadium (TiAlV) at concentrations of 4 x 10(7) particles/ml produced a mean prostaglandin E(2) release of 2627.6 pM; this was significantly higher than the 317.4 pM induced by titanium 7 -niobium alloy (TiAlNb) particles Commercially-pure titanium particles induced a release of 347.8 pM. In addition, TiAlV stimulated signific antly more release of the other cell mediators, interleukin-1, tumour necrosis factor and interleukin-6, At lower concentrations of particle s there was less mediator release and less obvious differences between materials. None of the materials caused significant toxicity, The lev els of inflammatory mediators released by phagocytic cells in response to wear particles may influence the amount of periprosthetic bone los s, Our findings have shown that in vitro studies can detect difference s in cellular response induced by particles of similar titanium alloys in common clinical use, although in vivo studies have shown little di fference, While in vitro studies should not be used as the only form o f assessment, they must be considered when assessing the relative bioc ompatibility of different implant materials.