title: Characteristics of polyethylene wear particles isolated from synovial fluid after mobile-bearing and posterior-stabilized total knee arthroplasties.
abstract: The size, shape, and number of polyethylene wear particles found in synovial fluids of patients 1 year after implantation of 22 well-functioning total knee prostheses (11 contemporary mobile-bearing type, 11 posterior-stabilized type) were determined. Polyethylene wear particles were isolated from synovial fluids and examined by scanning electron microscopy. Particle size (equivalent circle diameter) was 0.81 +/- 0.12 microm (mean +/- standard error) in mobile-bearing types and 0.78 +/- 0.08 microm in posterior-stabilized types. Particle shape (aspect ratio) was 1.94 +/- 0.13 in mobile-bearing types and 2.30 +/- 0.22 in posterior-stabilized types. Total numbers of particles were (1.75 +/- 1.02) x 10(8) in mobile-bearing and (1.16 +/- 0.57) x 10(8) in posterior-stabilized types. The differences in these parameters between the two groups were not statistically significant. In the early stages after surgery, contemporary mobile-bearing types were comparable to posterior-stabilized types in terms of polyethylene wear-particle generation. The present results do not support the proposition that has been put forward in the literature; namely, that the contemporary mobile-bearing design has an advantage, in terms of the polyethylene wear rate. These data suggest that the advantage of complete conformity in the femoro-tibial articulating surface of contemporary mobile-bearing design may be offset by wear of the mobile undersurface and slot, apart from the articulating surface.
authors.affiliation: Department of Orthopaedic Surgery, Osaka City University Medical School, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545-8585, Japan.
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Minoda
authors.forename: Akio
authors.initials: A
authors.lastname: Kobayashi
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Iwaki
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Miyaguchi
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kadoya
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Ohashi
authors.forename: Kunio
authors.initials: K
authors.lastname: Takaoka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D001672:Biocompatible Materials; D006801:Humans; D008875:Middle Aged; D009043:Motor Activity; D010003:Osteoarthritis / Q000601:surgery; D020959:Polyethylene / Q000302:isolation & purification*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013582:Synovial Fluid / Q000737:chemistry*; D013997:Time Factors; D016474:Weight-Bearing
chemical_list: D001672:Biocompatible Materials; D020959:Polyethylene