The influence of vacuum mixing on methylmethacrylate liberation from acrylic cement powder

Polymethylmethacrylate (PMMA) bone cement is a biomaterial used to anchor p rostheses during joint replacement surgery. Residual methylmethacrylate mon omer (MNA) may be related with the cytotoxic effect of PM MA. The aim of th e present paper was to investigate the effect of two different cement mixin g methods: hand stirring at atmospheric pressure and under partial vacuum ( 0.330 and 0.154 bar) on residual monomer liberation in phosphate buffer sal ine solution from acrylic cement powder. Residual MMA content was determine d by high-performance liquid chromatography. Mathematical models were appli ed to experimental dissolution data revealing that monomer release was sign ificantly reduced in bone cement powder obtained at 0.154 bar vacuum pressu re compared to the other mixing conditions. The kinetic models applied are consistent with a simple diffusion mechanism of the monomer from the polyme r matrix. (C) 2001 Elsevier Science B.V. All rights reserved.