title: The John Charnley Award: Highly crosslinked polyethylene in total hip arthroplasty decreases long-term wear: a double-blind randomized trial.
abstract: BACKGROUND
  The use of highly crosslinked polyethylene (HXLPE) is now commonplace for total hip arthroplasty. Hip simulator studies and short-term in vivo measurements suggest that the wear rate of some types of HXLPE is significantly less than conventional ultrahigh-molecular-weight polyethylene (UHMWPE). However, there are few long-term data to support its use.
  
  
  OBJECTIVE
  The aim of this study was to measure the long-term steady-state wear of HXLPE compared with UHMWPE liners in a prospective, double-blind, randomized controlled trial using radiostereometric analysis.
  
  
  METHODS
  Fifty-four patients were randomized to receive hip arthroplasties with either UHMWPE liners or HXLPE liners. Complete followup was available on 39 of these patients (72%). All patients received the same cemented stem and an uncemented acetabular component. Three-dimensional penetration of the head into the socket was determined at 10 years using a radiostereometric analysis system, which has an in vivo accuracy of <0.1 mm. Oxford Hip Scores were compared between the groups.
  
  
  RESULTS
  At 10 years there was significantly less wear of HXLPE (0.003 mm/year; 95% confidence interval [CI], ±0.010; SD 0.023; range, -0.057 to 0.074) compared with UHMWPE (0.030 mm/year; 95% CI, ±0.012; p<0.001; SD 0.0.27; range, -0.001 to 0.164). The volumetric penetration from 1 to 10 years for the UHMWPE group was 98 mm3 (95% CI, ±46 mm3; SD 102 mm3; range, -4 to 430 mm3) compared with 14 mm3 (95% CI, ±40 mm3; SD 91 mm3; range, -189 to 242 mm3) for the HXLPE group (p=0.01).
  
  
  CONCLUSIONS
  This study demonstrates that HXLPE has little detectable steady-state in vivo wear. This may result in fewer reoperations from loosening; however, careful clinical followup into the second decade still needs to be performed.
  
  
  METHODS
  Level I, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, NIHR Musculoskeletal Biomedical Research Unit, Nuffield Orthopaedic Centre, University of Oxford, Windmill Road, Oxford, OX3 7LD, UK.
authors.forename: Siôn
authors.initials: S
authors.lastname: Glyn-Jones
authors.forename: Geraint E R
authors.initials: GE
authors.lastname: Thomas
authors.forename: Patrick
authors.initials: P
authors.lastname: Garfjeld-Roberts
authors.forename: Roger
authors.initials: R
authors.lastname: Gundle
authors.forename: Adrian
authors.initials: A
authors.lastname: Taylor
authors.forename: Peter
authors.initials: P
authors.lastname: McLardy-Smith
authors.forename: David W
authors.initials: DW
authors.lastname: Murray
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D003432:Cross-Linking Reagents; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D020959:Polyethylene; D011095:Polyethylenes; D011474:Prosthesis Design; D011475:Prosthesis Failure; D059869:Radiostereometric Analysis; D013499:Surface Properties
chemical_list: D003432:Cross-Linking Reagents; D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene; D020959:Polyethylene