Bone cement containing coated radiopaque particles and its preparation
First Claim
1. Radiopaque acrylic bone cement for orthopaedic use, comprising a solid phase essentially composed of a powder of at least one poly(methyl acrylate)-based 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, characterised in that 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 polymerisation of said bone cement so as to keep its oxygen barrier properties.
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Accused Products
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.
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Citations
20 Claims
- 1. Radiopaque acrylic bone cement for orthopaedic use, comprising a solid phase essentially composed of a powder of at least one poly(methyl acrylate)-based 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, characterised in that 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 polymerisation of said bone cement so as to keep its oxygen barrier properties.
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17. Method for preparing a radiopaque acrylic bone cement for orthopaedic use, comprising the steps of:
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preparing a solid phase essentially composed of a powder of at least one poly(methyl methacrylate)-based polymer, one free-radical polymerization initiator and one radiopacifying material;
preparing a liquid phase composed of a mixture of at least one monomer, one accelerator and one stabilizer, mixing said solid phase with said liquid phase so as to perform polymerization in such a way that a bone cement matrix is obtained, in which the radiopacifying material is obtained by preparing a powder of metal particles of molecular weight equal or higher than 130 Dalton, mixtures, alloys or compounds thereof, said metal particles comprising tantalum and/or tungsten particles, and coating said particles with a layer of a polymer which is compatible with said matrix, said polymer coating layer being so selected to protect said metal particles from exposure to oxygen, said polymer coating layer being so sized that it does not completely dissolve in said liquid phase so as to keep its oxygen barrier properties. - View Dependent Claims (19, 20)
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Specification