title: [Polyethylene particles in synovial fluid after knee arthroplasty with a conventional or highly cross-linked polyethylene. Preliminary study].
abstract: OBJECTIVE
  In recent years cross-linked polyethylenes have been developed in an attempt to reduce the wear, as has been demonstrated in knee simulators. The aim is to assess, by counting particles of polyethylene in synovial fluid, whether the reduction in wear is confirmed in patients with a highly crosslinked polyethylene prosthesis.
  
  
  METHODS
  A prospective randomised study was designed. During the implantation of a knee prosthesis, one group of patients was assigned the use of a conventional polyethylene (group A), and the other group a highly crosslinked polyethylene (X3, Stryker Orthopaedics) (group B). At 12 months after surgery a knee arthrocentesis was performed, and the number of polyethylene particles was counted in a scanning electron microscopy. Fourteen samples from each group were studied.
  
  
  RESULTS
  Both groups were comparable in all study variables. We found no significant differences in the concentration of polyethylene particles/ml (1.49 ± 0.85 million in group A vs 1.42 ± 0.91 million in group B, P=.60) or the total number of isolated particles. We found no differences either in size or morphology of particles between both groups.
  
  
  CONCLUSIONS
  Although several in vitro studies in vitro using different types of highly crosslinked polyethylene found a significant reduction, we did not find that that wear was reduced in the knees of these patients. The great variability in the number of particles between individuals suggests that polyethylene wear in vivo depends on many factors, so perhaps the type of polyethylene is not the most significant factor.
authors.affiliation: Servicio de Cirugía Ortopédica y Traumatología, Parc de Salut Mar (Hospitales del Mar y Esperanza), Barcelona, España. Phinarejos@parcdesalutmar.cat
authors.forename: P
authors.initials: P
authors.lastname: Hinarejos
authors.forename: A
authors.initials: A
authors.lastname: Torres
authors.forename: I
authors.initials: I
authors.lastname: Piñol
authors.forename: D
authors.initials: D
authors.lastname: Valverde
authors.forename: E
authors.initials: E
authors.lastname: Prats
authors.forename: Ll
authors.initials: L
authors.lastname: Puig
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D005260:Female; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D020959:Polyethylene / Q000032:analysis*; D011446:Prospective Studies; D011475:Prosthesis Failure; D013582:Synovial Fluid / Q000737:chemistry*; D016896:Treatment Outcome
chemical_list: D020959:Polyethylene