title: 2006 Frank Stinchfield Award: grafting of biocompatible polymer for longevity of artificial hip joints.
abstract: Aseptic loosening induced by wear particles from the polyethylene liner is likely the most common cause of long-term total hip arthroplasty failure. We developed a novel hip polyethylene liner with the surface graft of a biocompatible phospholipid polymer, 2-methacryloyloxyethyl phosphorylcholine (MPC), and previously reported the grafting decreased the short-term production of wear particles and the subsequent bone resorptive responses. For clinical application, we investigated the stability of the 2-methacryloyloxyethyl phosphorylcholine grafting during sterilization and the wear resistance of the sterilized liner during longer loading comparable to clinical usage. Radiographic spectroscopy confirmed the stability of the 2-methacryloyloxyethyl phosphorylcholine polymer on the liner surface after the gamma irradiation. We used a hip wear simulator up to 1 x 10(7) cycles to test sterilized cross-linked polyethylene liners with and without 2-methacryloyloxyethyl phosphorylcholine grafting. The 2-methacryloyloxyethyl phosphorylcholine grafting markedly decreased the friction, the production of wear particles, and the wear of the liner surface. These data suggest a marked improvement in the wear resistance of the polyethylene liner by the 2-methacryloyloxyethyl phosphorylcholine grafting for clinically relevant periods after sterilization, indicating 2-methacryloyloxyethyl phosphorylcholine grafting is a promising technology for extending longevity of artificial hips.
authors.affiliation: Department of Sensory and Motor System Medicine, Faculty of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan. moro-ort@h.u-tokyo.ac.jp
authors.forename: Toru
authors.initials: T
authors.lastname: Moro
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takatori
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ishihara
authors.forename: Kozo
authors.initials: K
authors.lastname: Nakamura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawaguchi
mesh_terms: D005720:Gamma Rays; D006622:Hip Prosthesis; D008422:Materials Testing; D008689:Methacrylates; D010767:Phosphorylcholine / Q000031:analogs & derivatives*; D020959:Polyethylene; D011475:Prosthesis Failure; D013242:Sterilization; D013314:Stress, Mechanical
chemical_list: D008689:Methacrylates; D010767:Phosphorylcholine; C070638:2-methacryloyloxyethyl phosphorylcholine; D020959:Polyethylene