Effect of PMMA cement radical polymerisation on the inflammatory response

The effect of the radical polymerisation taking place during the hardening of the polymethyl methacrylate (PMMA) bone cements is known to cause bone necrosis through the relatively high exothermic reaction and the leaching of toxic non reacted monomers. The inflammatory response towards this class of cements has also been shown and ascribed mainly to the phagocytosis of the material particles. However, the effect of the radical polymerisation on the adsorption of plasma proteins and on the activation of monocytes/macrophages when the material is in a non-phagocytosable dimension has not been elucidated. In the present work, the polymerisation of three bone cements, CMW-1, Palavit and Simplex-P in a clinically reflective environment and its effect on the formation of a surface conditioning film as well as on the inflammatory cell activation were investigated. The data showed that on CMW and Simplex-P the polymerisation was not fully accomplished. CMW released high levels of non-reacted monomers, no significant macrophage adhesion and high oxidative burst and cytokine production. The relatively lower levels of released monomers in Simplex and Palavit seemed to promote a lower inflammatory response while cell adhesion was favoured by patches of plasma components entrapped in the hardening dough during the polymerisation.