title: Centralization and the relationship between volume and outcome in knee arthroplasty procedures.
abstract: BACKGROUND
  Centralization aims to reduce adverse patient outcomes by concentrating complex surgical procedures in specified hospitals.
  
  
  OBJECTIVE
  This review assessed the efficacy of centralization for knee arthroplasty by examining the relationship between hospital and surgeon volume and patient outcomes.
  
  
  METHODS
  The systematic review identified studies using multiple databases, including Medline and Embase. Two independent researchers ensured studies met the inclusion criteria. Morbidity, mortality, length of stay, financial outcomes and statistical rigour were examined. Correlations between volume and outcome were reported.
  
  
  RESULTS
  Twelve primary knee arthroplasty studies examined hospital volume, which was significantly associated with decreased morbidity (five of seven studies), mortality (two of five studies) and length of stay (two of three studies). Three primary knee arthroplasty studies examined surgeon volume, which was significantly associated with decreased morbidity (two of three studies), mortality (zero of two studies) and length of stay (one of one study). Two revision knee arthroplasty studies examined hospital volume. One study examined but did not test for significance between hospital volume and patient morbidity; both studies examined volume and patient mortality reporting inconclusive results; and one study reported no significant association between volume and length of stay. None of the revision knee arthroplasty studies examined surgeon volume.
  
  
  CONCLUSIONS
  Significant associations between increased hospital and surgeon volume and improved patient outcomes were reported. However, when these results were separated by arthroplasty type, the association appeared tenuous. Judgements regarding centralization of knee arthroplasty should be made with caution until further evidence is published.
authors.affiliation: Australian Safety and Efficacy Register of New Interventional Procedures-Surgical, Royal Australasian College of Surgeons, Adelaide, Australia.
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Marlow
authors.forename: Bruce
authors.initials: B
authors.lastname: Barraclough
authors.forename: Neil A
authors.initials: NA
authors.lastname: Collier
authors.forename: Ian C
authors.initials: IC
authors.lastname: Dickinson
authors.forename: Jonathon
authors.initials: J
authors.lastname: Fawcett
authors.forename: John C
authors.initials: JC
authors.lastname: Graham
authors.forename: Guy J
authors.initials: GJ
authors.lastname: Maddern
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000706:statistics & numerical data*; D002497:Centralized Hospital Services / Q000706:statistics & numerical data*; D013502:General Surgery / Q000706:statistics & numerical data; D014943:Global Health; D006801:Humans; D007902:Length of Stay; D009017:Morbidity; D010043:Outcome and Process Assessment, Health Care