title: Knee arthroplasty in Denmark, Norway and Sweden. A pilot study from the Nordic Arthroplasty Register Association.
abstract: OBJECTIVE
  The number of national arthroplasty registries is increasing. However, the methods of registration, classification, and analysis often differ.
  
  
  METHODS
  We combined data from 3 Nordic knee arthroplasty registers, comparing demographics, methods, and overall results. Primary arthroplasties during the period 1997-2007 were included. Each register produced a dataset of predefined variables, after which the data were combined and descriptive and survival statistics produced.
  
  
  RESULTS
  The incidence of knee arthroplasty increased in all 3 countries, but most in Denmark. Norway had the lowest number of procedures per hospital-less than half that of Sweden and Denmark. The preference for implant brands varied and only 3 total brands and 1 unicompartmental brand were common in all 3 countries. Use of patellar button for total knee arthroplasty was popular in Denmark (76%) but not in Norway (11%) or Sweden (14%). Uncemented or hybrid fixation of components was also more frequent in Denmark (22%) than in Norway (14%) and Sweden (2%). After total knee arthroplasty for osteoarthritis, the cumulative revision rate (CRR) was lowest in Sweden, with Denmark and Norway having a relative risk (RR) of 1.4 (95% CI: 1.3-1.6) and 1.6 (CI: 1.4-1.7) times higher. The result was similar when only including brands used in more than 200 cases in all 3 countries (AGC, Duracon, and NexGen). After unicompartmental arthroplasty for osteoarthritis, the CRR for all models was also lowest in Sweden, with Denmark and Norway having RRs of 1.7 (CI: 1.4-2.0) and 1.5 (CI: 1.3-1.8), respectively. When only the Oxford implant was analyzed, however, the CRRs were similar and the RRs were 1.2 (CI: 0.9-1.7) and 1.3 (CI: 1.0-1.7).
  
  
  CONCLUSIONS
  We found considerable differences between the 3 countries, with Sweden having a lower revision rate than Denmark and Norway. Further classification and standardization work is needed to permit more elaborate studies.
authors.affiliation: The Swedish Knee Arthroplasty Register, Dept of Orthopedics, Clinical Sciences, Lund, Lund University, Sweden. otto.robertsson@med.lu.se
authors.forename: Otto
authors.initials: O
authors.lastname: Robertsson
authors.forename: Svetlana
authors.initials: S
authors.lastname: Bizjajeva
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: Fenstad
authors.forename: Ove
authors.initials: O
authors.lastname: Furnes
authors.forename: Lars
authors.initials: L
authors.lastname: Lidgren
authors.forename: Frank
authors.initials: F
authors.lastname: Mehnert
authors.forename: Anders
authors.initials: A
authors.lastname: Odgaard
authors.forename: Alma Becic
authors.initials: AB
authors.lastname: Pedersen
authors.forename: Leif Ivar
authors.initials: LI
authors.lastname: Havelin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data; D003718:Denmark; D005260:Female; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D009664:Norway; D010865:Pilot Projects; D012042:Registries; D013548:Sweden; D016896:Treatment Outcome