title: Wear of retrieved UHMWPE hip liners.
abstract: After the gamma-irradiation sterilization, the most widely used orthopaedic grade polymer bearing liner material for the total joint replacement, ultra-high molecular weight polyethylene (UHMWPE), degrades through the progressive in vivo oxidation. The oxidative degradation makes UHMWPE brittle and leads to reduction of its mechanical properties. In this study, the effect of the in vivo post-irradiation ageing time on the wear of UHMWPE was investigated. Twelve retrieved polyethylene hip liners implanted for 3-16 years and then stored in the air for 1.5-8 years were used. Two types of the pin-on-disk wear testing were conducted. The uni-directional repeat pass rotating and the linear reciprocating wear testing were done with stainless steel disks against stationary polyethylene pins under 4MPa at 1Hz with bovine serum lubrication. Wear of the retrieved polyethylene hip liners does not have significant correlation with the in vivo or total ageing time. The linear reciprocal sliding motion generated a more pronounced wear than the uni-directional repeat pass sliding motion. This indicates that the kinematic motion significantly affects the wear of aged UHMWPE, having a brittle, white band region.
authors.affiliation: Sejong University, Bioengineering Research Center, 98 Kunja-dong, Kwangjin-gu, Seoul 143-747, Korea. kwonlee@sejong.ac.kr
authors.forename: Kwon-Yong
authors.initials: KY
authors.lastname: Lee
authors.forename: Shin-Yoon
authors.initials: SY
authors.lastname: Kim
authors.forename: Daehwan
authors.initials: D
authors.lastname: Shin
authors.forename: Sungjae
authors.initials: S
authors.lastname: Lee
authors.forename: Sukyoung
authors.initials: S
authors.lastname: Kim
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D001696:Biomechanical Phenomena; D005720:Gamma Rays; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D010084:Oxidation-Reduction; D011095:Polyethylenes / Q000528:radiation effects / Q000592:standards*
chemical_list: D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene