title: Do modern total knee replacements offer better value for money? A health economic analysis.
abstract: OBJECTIVE
  Cost effectiveness is an increasingly important factor in today's healthcare environment, and selection of arthroplasty implant is not exempt from such concerns. Quality adjusted life years (QALYs) are the typical tool for this type of evaluation. Using this methodology, joint arthroplasty has been shown to be cost effective; however, studies directly comparing differing prostheses are lacking.
  
  
  METHODS
  Data was gathered in a single-centre prospective double-blind randomised controlled trial comparing the outcome of modern and traditional knee implants, using the Short Form 6 dimensional (SF-6D) score and quality adjusted life year (QALY) methodology.
  
  
  RESULTS
  There was significant improvement in the SF-6D score for both groups at one year (p < 0.0001). The calculated overall life expectancy for the study cohort was 15.1 years, resulting in an overall QALY gain of 2.144 (95% CI 1.752-2.507). The modern implant group demonstrated a small improvement in SF-6D score compared to the traditional design at one year (0.141 versus 0.143, p = 0.94). This difference resulted in the modern implant costing £298 less per QALY at one year.
  
  
  CONCLUSIONS
  This study demonstrates that modern implant technology does not influence the cost-effectiveness of TKA using the SF-6D and QALY methodology. This type of analysis however assesses health status, and is not sensitive to joint specific function. Evolutionary design changes in implant technology are thus unlikely to influence QALY analysis following joint replacement, which has important implications for implant procurement.
authors.affiliation: Department of Trauma and Orthopaedics, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, EH16 4SB, Edinburgh, UK, d.f.hamilton@ed.ac.uk.
authors.forename: David F
authors.initials: DF
authors.lastname: Hamilton
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Clement
authors.forename: Richard
authors.initials: R
authors.lastname: Burnett
authors.forename: James T
authors.initials: JT
authors.lastname: Patton
authors.forename: Mathew
authors.initials: M
authors.lastname: Moran
authors.forename: Colin R
authors.initials: CR
authors.lastname: Howie
authors.forename: A H R W
authors.initials: AH
authors.lastname: Simpson
authors.forename: Paul
authors.initials: P
authors.lastname: Gaston
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000191:economics / Q000295:instrumentation* / Q000379:methods*; D003362:Cost-Benefit Analysis; D004185:Disability Evaluation; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006801:Humans; D007719:Knee Joint / Q000502:physiology / Q000601:surgery; D007720:Knee Prosthesis / Q000191:economics*; D008017:Life Expectancy; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D011788:Quality of Life; D019057:Quality-Adjusted Life Years; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome