title: Wear of conventional and cross-linked ultra-high-molecular-weight polyethylene acetabular cups against polished and roughened CoCr femoral heads in a biaxial hip simulator.
abstract: The wear of acetabular cups made from conventional gamma-sterilized, and electron-beam cross-linked ultra-high-molecular-weight polyethylene was studied with a biaxial hip wear simulator. The femoral heads were either polished or roughened so that they represented the type of roughening and the value of surface roughness (R(a) = 0.14-0.18 micro m) observed in the roughest explanted femoral heads. The lubricant was diluted calf serum, and the test length 3 million cycles. The mean wear rate and standard deviation of conventional polyethylene cups against polished and against roughened heads was 11.6 +/- 0.07 and 64.4 +/- 10.1 mg per 1 million cycles, respectively. The latter value closely corresponds to that measured from explanted Charnley prostheses. Against polished heads, cross-linked polyethylene cups showed net weight gain, whereas against roughened heads, their mean wear rate was 2.4 +/- 0.3 mg per 1 million cycles. The mean equivalent circle diameters of polyethylene wear particles produced in the above four categories were: conventional/roughened 0.32 micro m, cross-linked/roughened 0.29 micro m, conventional/polished 0.28 micro m, cross-linked/polished 0.23 micro m. The size ranges and shapes were close to those seen in particles isolated from tissue samples. In conclusion, the tests indicated that electron-beam irradiation effectively reduces the harmful polyethylene wear particle production in total hip arthroplasty.
authors.affiliation: Department of Mechanical Engineering, Helsinki University of Technology, P O Box 4300, FIN-02015 HUT, Finland. vesa.saikko@hut.fi
authors.forename: Vesa
authors.initials: V
authors.lastname: Saikko
authors.forename: Olof
authors.initials: O
authors.lastname: Calonius
authors.forename: Jaakko
authors.initials: J
authors.lastname: Keränen
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry / Q000528:radiation effects; D002858:Chromium Alloys; D003432:Cross-Linking Reagents; D004583:Electrons; D006622:Hip Prosthesis; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D010316:Particle Size; D020959:Polyethylene / Q000138:chemical synthesis / Q000737:chemistry / Q000528:radiation effects; D011475:Prosthesis Failure; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D002858:Chromium Alloys; D003432:Cross-Linking Reagents; D020959:Polyethylene