title: 5-year experience of highly cross-linked polyethylene in cemented and uncemented sockets: two randomized studies using radiostereometric analysis.
abstract: BACKGROUND
  Laboratory tests and early clinical studies have shown that highly cross-linked polyethylene (PE) markedly improves wear resistance compared to conventional PE. We evaluated this type of PE in two randomized clinical studies using radiostereometric analysis (RSA). The 2- and 3-year follow-up of these studies have already been reported. We found a lower penetration rate for the highly cross-linked PE than for conventional PE. We now report the outcome after 5 years.
  
  
  METHODS
  60 patients (61 hips) with a median age of 55 years were randomized to receive either highly cross-linked PE (Durasul) or conventional cemented all-polyethylene sockets of the same design. 55 patients (56 hips) were followed for 5 years. In the second study, 32 patients (64 hips) with a median age of 48 years and with bilateral primary or secondary osteoarthritis of the hip had hybrid total hip arthroplasty with liners made of highly cross-linked PE (Longevity) on one side and conventional PE on the other. 23 patients in this study have passed the 5-year follow-up.
  
  
  RESULTS
  Bedding-in and creep for the Durasul all-PE was reached by 2 years, and by 1 year for the Longevity liners. In both control groups with conventional PE, this was reached by 6 months. The steady-state wear rate was close to zero in the two study groups and 0.06 mm/year for the conventional PE in the two control groups.
  
  
  CONCLUSIONS
  We found that use of highly crosslinked PE instead of conventional PE reduced the wear by more than 95%, which supports continued use of this type of PE in young, active patients.
authors.affiliation: Department of Orthopedics, Institute of Surgical Science, Sahlgrenska University Hospital, Göteborg University, Göteborg, Sweden. georgios.digas@vgregion.se
authors.forename: Georgios
authors.initials: G
authors.lastname: Digas
authors.forename: Johan
authors.initials: J
authors.lastname: Kärrholm
authors.forename: Jonas
authors.initials: J
authors.lastname: Thanner
authors.forename: Peter
authors.initials: P
authors.lastname: Herberts
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods; D015519:Bone Density; D002484:Cementation; D020099:Coated Materials, Biocompatible; D005260:Female; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D020959:Polyethylene; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D020099:Coated Materials, Biocompatible; D020959:Polyethylene