Patent ID: 8025696

Claim:
An artificial meniscus, a base material of which is a hydrogel having a semi-interpenetrating network structure or an interpenetrating network structure wherein the hydrogel is produced by a process comprising: a first step of polymerizing and crosslinking a first monomer component, of which 10 mol % or more is an electrically charged unsaturated monomer selected from the group consisting of 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, methacrylic acid and a salt thereof, in the presence of a solvent, to thereby form a first network structure; and a second step of introducing a second monomer component, of which 60 mol % or more is an electrically neutral unsaturated monomer selected from the group consisting of acrylamide, N-isopropylacrylamide, N,N-dimethyl-acrylamide, vinylpyridine, styrene, methylmethacrylate, fluorine-containing unsaturated monomer, hydroxyethyl acrylate and vinyl acetate, into the first network structure and then polymerizing the second monomer component in the presence of a solvent, to thereby form a polymer in the first network structure; or optionally, further crosslinking the polymer to thereby form a second network structure in the first network structure, and in the case of the second monomer component being polymerized and crosslinked, the degree of crosslinking is set to be lower than the degree of crosslinking when the first monomer component is polymerized and crosslinked and wherein the molar ratio in amount of the first monomer component to the second monomer component is from 1:2 to 1:100 wherein the hydrogel has a compression stress at rupture of 3 to 40 MPa.