title: Trends and geographical variation of primary hip and knee joint replacement in Germany.
abstract: OBJECTIVE
  Considerable variation in total hip replacement and total knee replacement (THR/TKR) between regions has been described. The aim of this study was to explore geographical variation in THR and TKR in Germany and to analyse potentially explanatory variables.
  
  
  METHODS
  We used data of Germany's largest statutory health insurer. Between 2005 and 2009 451,108 THR and 335,022 TKR were performed. Age-standardised joint replacement rates were calculated for 16 federal states and 407 counties. We performed cluster (Moran's I) and spatial error regression analyses including regional deprivation, osteoarthritis rate, urbanity and number of orthopaedic specialists as dependent variables on county level.
  
  
  RESULTS
  In 2009 the overall age-standardised and crude rates were 148.9 (95% CI (confidence interval) 147.6-151.1) and 290.2 for THR, and 132.5 (95% CI 131.3-133.6) and 232.7 for TKR. Between counties THR rates differed by factor 2 (106.1-215.8) and showed significant clusters with high utilisation in South and Northwest Germany. TKR rates differed by factor 3.2 (69.1-219.5) and were also high in South Germany whereas almost all areas in East Germany showed low replacement rates. Differences were pronounced when restricting the analysis to cases with an indication of osteoarthritis. All tested predictors could be identified as significant explanatory variables (each P < 0.001).
  
  
  CONCLUSIONS
  This study proofed considerable and consistent geographic variation of THR and TKR in Germany. Thereby relevant explanatory factors were identified. These results may foster the discussion and future research in health services which should include areas of patients' and doctors' expectation, financial aspects and an outcome-based definition of appropriate supply.
authors.affiliation: German Society of Orthopaedics and Orthopaedic Surgery, Immenstadt, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Schäfer
authors.forename: R
authors.initials: R
authors.lastname: Pritzkuleit
authors.forename: C
authors.initials: C
authors.lastname: Jeszenszky
authors.forename: J
authors.initials: J
authors.lastname: Malzahn
authors.forename: W
authors.initials: W
authors.lastname: Maier
authors.forename: K P
authors.initials: KP
authors.lastname: Günther
authors.forename: F
authors.initials: F
authors.lastname: Niethard
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000706:statistics & numerical data / Q000639:trends*; D019645:Arthroplasty, Replacement, Knee / Q000706:statistics & numerical data / Q000639:trends*; D005260:Female; D005843:Geography; D005858:Germany / Q000453:epidemiology; D006296:Health Services / Q000706:statistics & numerical data / Q000639:trends; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000453:epidemiology / Q000601:surgery*; D020370:Osteoarthritis, Knee / Q000453:epidemiology / Q000601:surgery*; D012044:Regression Analysis; D012189:Retrospective Studies