title: Comparison of in vivo polyethylene wear particles between mobile- and fixed-bearing TKA in the same patients.
abstract: OBJECTIVE
  Polyethylene wear particle generation is one of the most important factors that affects the mid- to long-term results of total knee arthroplasties (TKA). Mobile-bearing total knee prostheses were developed to reduce polyethylene wear generation. However, whether mobile-bearing prostheses actually generate fewer polyethylene wear particles than fixed-bearing prostheses remains controversial. The aim of this study was to compare, within individual patients, the in vivo polyethylene wear particles created by a newly introduced mobile-bearing prosthesis in one knee and a conventional fixed-bearing prosthesis in other knee.
  
  
  METHODS
  Eighteen patients receiving bilateral TKAs to treat osteoarthritis were included. The synovial fluid was obtained from 36 knees at an average of 3.5 years after the operation. The in vivo polyethylene wear particles were isolated from the synovial fluid using a previously validated method and examined using a scanning electron microscope and an image analyser.
  
  
  RESULTS
  The size and shape of the polyethylene wear particles from the mobile-bearing prostheses were similar to those from the conventional fixed-bearing prostheses. Although the number of wear particles from the mobile-bearing prosthesis (1.63 × 107counts/knee) appeared smaller than that from the fixed-bearing prosthesis (2.16 × 107counts/knee), the difference was not statistically significant.
  
  
  CONCLUSIONS
  The current in vivo study shows that no statistically significant differences were found between the polyethylene wear particles generated by a newly introduced mobile-bearing PS prosthesis and a conventional fixed-bearing PS prosthesis during the early clinical stage after implantation.
  
  
  METHODS
  Therapeutic study, Level III.
authors: Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi Abeno-ku, Osaka, 545-8585, Japan. yminoda@msic.med.osaka-cu.ac.jp.
authors: Yukihide
authors: Y
authors: Minoda
authors: Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi Abeno-ku, Osaka, 545-8585, Japan.
authors: Kanako
authors: K
authors: Hata
authors: Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi Abeno-ku, Osaka, 545-8585, Japan.
authors: Mitsuhiko
authors: M
authors: Ikebuchi
authors: Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi Abeno-ku, Osaka, 545-8585, Japan.
authors: Shigekazu
authors: S
authors: Mizokawa
authors: Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi Abeno-ku, Osaka, 545-8585, Japan.
authors: Yoichi
authors: Y
authors: Ohta
authors: Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi Abeno-ku, Osaka, 545-8585, Japan.
authors: Hiroaki
authors: H
authors: Nakamura
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D006801:Humans; D007720:Knee Prosthesis; D008855:Microscopy, Electron, Scanning; D020370:Osteoarthritis, Knee / Q000601:surgery; D020959:Polyethylene / Q000032:analysis*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013582:Synovial Fluid / Q000737:chemistry*
chemical_list: D020959:Polyethylene
keywords: Fixed-bearing prosthesis; Mobile-bearing prosthesis; Polyethylene wear particle; Total knee arthroplasty