Bone cement containing coated radiopaque particles and its preparation

Abstract

An acrylic radiopaque bone cement for orthopedic use comprises a solid phase composed of a mixture of at least one poly(methyl acrylate)-based polymer, one free-radical polymerization initiator and one or more substances opaque to X-rays, and a liquid phase substantially composed of a mixture of at least one monomer, one accelerator and one stabilizer. The radiopaque substances comprise metallic tungsten and tantalum particles, compounds or mixtures thereof, covered with a polymer coating compatible with said bone cement. The coating layer of the particles of radiopaque substances is an acrylic polymer based on poly(methyl methacrylate). The amount of radiopacifying element is between 1% and 20% by weight, relative to the solid phase, preferably between 2% and 5% by weight, relative to the solid phase. The solid phase may additionally comprise one or more pharmacologically active substances. The method for its preparation consists in preparing the radiopacifying material by coating the metal particles with a layer of a polymer which is compatible with the matrix and exhibits oxygen barrier properties such that said layer does not dissolve completely in the liquid phase so as to keep its oxygen barrier properties at least partly unchanged.