title: Third-body abrasive wear of tibial polyethylene inserts combined with metallic and ceramic femoral components in a knee simulator study.
abstract: OBJECTIVE
  Total knee arthroplasties have reached a high grade of quality and safety, but most often fail because of aseptic implant loosening caused by polyethylene wear debris. Wear is generated at the articulating surfaces, e.g. caused by third-body particles. The objective of this experimental study was to determine the wear of tibial polyethylene inserts combined with metallic and ceramic femoral components under third-body wear conditions initiated by bone cement particles.
  
  
  METHODS
  Wear testing using a cemented unconstrained bicondylar knee endoprosthesis (Multigen Plus CR knee system) was performed in a knee wear simulator. Tibial polyethylene inserts were combined with the identical femoral component design, but made of two different materials (cobalt-chromium and ceramic). Bone cement debris including zirconium oxide particles was added every 500,000 cycles between the articulating surfaces. After 5 million load cycles, the amount of wear was determined gravimetrically and compared with results from standard wear test conditions. The surfaces of tibial inserts were also analyzed.
  
  
  RESULTS
  The average gravimetrical wear of the tibial polyethylene inserts in combination with  cobalt-chromium and ceramic femoral components under third-body wear conditions amounted to 31.88 ± 4.53 mg and 13.06 ± 1.88 mg after 5 million cycles, respectively, and was higher than under standard wear test conditions in both cases.
  
  
  CONCLUSIONS
  The wear simulator test demonstrates that wear of polyethylene inserts under third-body wear conditions, in combination with ceramic femoral components, was significantly lower than with metallic femoral components.
authors: Department of Orthopedics, University Medicine Rostock, 18057 Rostock, Germany. carmen.zietz@med.uni-rostock.de
authors: Carmen
authors: C
authors: Zietz
authors: Philipp
authors: P
authors: Bergschmidt
authors: Regina
authors: R
authors: Lange
authors: Wolfram
authors: W
authors: Mittelmeier
authors: Rainer
authors: R
authors: Bader
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D001585:Benzoyl Peroxide / Q000737:chemistry; D001843:Bone Cements / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry*; D019544:Equipment Failure Analysis; D005269:Femur / Q000601:surgery*; D007720:Knee Prosthesis; D008422:Materials Testing; D020366:Methylmethacrylate / Q000737:chemistry; D010316:Particle Size; D011095:Polyethylenes / Q000737:chemistry*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D013499:Surface Properties; D013977:Tibia / Q000601:surgery*; D014800:Vitallium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry
chemical_list: D001843:Bone Cements; D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene; D014800:Vitallium; D020366:Methylmethacrylate; D015040:Zirconium; C028541:zirconium oxide; D001585:Benzoyl Peroxide