Improving the wear resistance of UHMWPE implants by in situ precipitation of hyaluronic acid using supercritical fluid technology

Recently, the increase in the number of patients who require a hip or knee implant, combined with the reduction of age at which this implant is demanded, emphasizes the urgent need for the development of new materials with enhanced mechanical and tribological properties. In this work, a new technique called supercritical in situ precipitation (SCisP) has been employed to manufacture a blend made of ultra-high molecular weight polyethylene with added vitamin E (UHMWPEvit) plus a hyaluronic acid (HA) derivative. The precipitation of the HA derivative within the pores of a porous UHMWPEvit preform allows getting a blend after the post-processing of the SCisP product. Blend characterization results report the reduction of friction coefficient and wear rate in comparison to reference UHMWPEvit, probably due to the improvement in the wettability that hyaluronic derivative produces. Manufacturing times and raw material consumption have been drastically reduced by SCisP in comparison to processes reported up to now. Moreover, preliminary studies varying the conditions of the process, i.e. the type of hyaluronic acid derivative, solvent and number of injections, establish the basis of this technique for further development and open an interesting route in the manufacture of medical devices. (C) 2014 Elsevier B.V. All rights reserved.