title: PMMA third-body wear after unicondylar knee arthroplasty decuples the UHMWPE wear particle generation in vitro.
abstract: BACKGROUND
  Overlooked polymethylmethacrylate after unicondylar knee arthroplasty can be a potential problem, since this might influence the generated wear particle size and morphology. The aim of this study was the analysis of polyethylene wear in a knee wear simulator for changes in size, morphology, and particle number after the addition of third-bodies.
  
  
  METHODS
  Fixed bearing unicondylar knee prostheses (UKA) were tested in a knee simulator for 5.0 million cycles. Following bone particles were added for 1.5 million cycles, followed by 1.5 million cycles with PMMA particles. A particle analysis by scanning electron microscopy of the lubricant after the cycles was performed. Size and morphology of the generated wear were characterized. Further, the number of particles per 1 million cycles was calculated for each group.
  
  
  RESULTS
  The particles of all groups were similar in size and shape. The number of particles in the PMMA group showed 10-fold higher values than in the bone and control group (PMMA: 10.251 × 10(12); bone: 1.145 × 10(12); control: 1.804 × 10(12)).
  
  
  CONCLUSIONS
  The addition of bone or PMMA particles in terms of a third-body wear results in no change of particle size and morphology. PMMA third-bodies generated tenfold elevated particle numbers. This could favor an early aseptic loosening.
authors: Department of Orthopedic Surgery, University Hospital of Munich (LMU), Campus Großhadern, Marchioninistraße 15, 81377 Munich, Germany.
authors: Alexander Christoph
authors: AC
authors: Paulus
authors: Department of Orthopedic Surgery, University Hospital of Munich (LMU), Campus Großhadern, Marchioninistraße 15, 81377 Munich, Germany.
authors: Manja
authors: M
authors: Franke
authors: Department of Orthopedic Surgery, University Hospital of Munich (LMU), Campus Großhadern, Marchioninistraße 15, 81377 Munich, Germany.
authors: Michael
authors: M
authors: Kraxenberger
authors: Department of Orthopedic Surgery, University Hospital of Munich (LMU), Campus Großhadern, Marchioninistraße 15, 81377 Munich, Germany.
authors: Christian
authors: C
authors: Schröder
authors: Department of Orthopedic Surgery, University Hospital of Munich (LMU), Campus Großhadern, Marchioninistraße 15, 81377 Munich, Germany.
authors: Volkmar
authors: V
authors: Jansson
authors: Department of Orthopedic Surgery, University Hospital of Munich (LMU), Campus Großhadern, Marchioninistraße 15, 81377 Munich, Germany.
authors: Sandra
authors: 0000-0003-2065-432X
authors: S
authors: Utzschneider
mesh_terms: D019645:Arthroplasty, Replacement, Knee; D006801:Humans; D007720:Knee Prosthesis; D008422:Materials Testing; D052638:Particulate Matter / Q000737:chemistry*; D019904:Polymethyl Methacrylate / Q000737:chemistry*
chemical_list: D052638:Particulate Matter; D019904:Polymethyl Methacrylate