Patent ID: 7186761

Claim:
Radiopaque acrylic bone cement for orthopedic use, comprising a solid phase essentially composed of a powder of at least one acrylic polymer, one free-radical polymerization initiator and one radiopacifying material, and a liquid phase substantially composed of a mixture of at least one monomer, one accelerator and one stabilizer, said solid phase being capable of hardening upon mixing thereof with said liquid phase so as to give a bone cement matrix, wherein said radiopacifying material comprises particles of metals having molecular weight equal to or higher than 130 Dalton, mixtures, alloys or compounds thereof, which particles are covered with a coating layer of a polymer which is compatible with said matrix, wherein said metal particles comprise tantalum and/or tungsten particles, said polymer coating layer covering each of said metal particles to protect them from exposure to oxygen, said coating layer being so sized that it does not completely dissolve in said liquid phase during polymerization of said bone cement so as to keep its oxygen barrier properties.