title: The cost-effectiveness of surgical treatment of medial unicompartmental knee osteoarthritis in younger patients: a computer model-based evaluation.
abstract: BACKGROUND
  Surgical options for the management of medial compartment osteoarthritis of the varus knee include high tibial osteotomy, unicompartmental knee arthroplasty, and total knee arthroplasty. We sought to determine the cost-effectiveness of high tibial osteotomy and unicompartmental knee arthroplasty as alternatives to total knee arthroplasty for patients fifty to sixty years of age.
  
  
  METHODS
  We built a probabilistic state-transition computer model with health states defined by pain, postoperative complications, and subsequent surgical procedures. We estimated transition probabilities from published literature. Costs were determined from Medicare reimbursement schedules. Health outcomes were measured in quality-adjusted life-years (QALYs). We conducted analyses over patients' lifetimes from the societal perspective, with health and cost outcomes discounted by 3% annually. We used probabilistic sensitivity analyses to account for uncertainty in data inputs.
  
  
  RESULTS
  The estimated discounted QALYs were 14.62, 14.63, and 14.64 for high tibial osteotomy, unicompartmental knee arthroplasty, and total knee arthroplasty, respectively. Discounted total direct medical costs were $20,436 for high tibial osteotomy, $24,637 for unicompartmental knee arthroplasty, and $24,761 for total knee arthroplasty (in 2012 U.S. dollars). The incremental cost-effectiveness ratio (ICER) was $231,900 per QALY for total knee arthroplasty and $420,100 per QALY for unicompartmental knee arthroplasty. Probabilistic sensitivity analyses showed that, at a willingness-to-pay (WTP) threshold of $50,000 per QALY, high tibial osteotomy was cost-effective 57% of the time; total knee arthroplasty, 24%; and unicompartmental knee arthroplasty, 19%. At a WTP threshold of $100,000 per QALY, high tibial osteotomy was cost-effective 43% of time; total knee arthroplasty, 31%; and unicompartmental knee arthroplasty, 26%.
  
  
  CONCLUSIONS
  In fifty to sixty-year-old patients with medial unicompartmental knee osteoarthritis, high tibial osteotomy is an attractive option compared with unicompartmental knee arthroplasty and total knee arthroplasty. This finding supports greater utilization of high tibial osteotomy for these patients. The cost-effectiveness of high tibial osteotomy and of unicompartmental knee arthroplasty depend on rates of conversion to total knee arthroplasty and the clinical outcomes of the conversions.
authors.affiliation: Orthopedic and Arthritis Center for Outcomes Research (J.F.K., J.N.K., and E.L.), Department of Orthopedic Surgery (J.F.K., T.S.T., J.N.K., and E.L.), Brigham and Women's Hospital, 75 Francis Street, BC-4016, Boston, MA 02115. E-mail address for E. Losina: elosina@partners.org.
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Konopka
authors.affiliation: Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, 850 Boylston Street, Chestnut Hill, MA 02467.
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Gomoll
authors.affiliation: Orthopedic and Arthritis Center for Outcomes Research (J.F.K., J.N.K., and E.L.), Department of Orthopedic Surgery (J.F.K., T.S.T., J.N.K., and E.L.), Brigham and Women's Hospital, 75 Francis Street, BC-4016, Boston, MA 02115. E-mail address for E. Losina: elosina@partners.org.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Thornhill
authors.affiliation: Orthopedic and Arthritis Center for Outcomes Research (J.F.K., J.N.K., and E.L.), Department of Orthopedic Surgery (J.F.K., T.S.T., J.N.K., and E.L.), Brigham and Women's Hospital, 75 Francis Street, BC-4016, Boston, MA 02115. E-mail address for E. Losina: elosina@partners.org.
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Katz
authors.affiliation: Orthopedic and Arthritis Center for Outcomes Research (J.F.K., J.N.K., and E.L.), Department of Orthopedic Surgery (J.F.K., T.S.T., J.N.K., and E.L.), Brigham and Women's Hospital, 75 Francis Street, BC-4016, Boston, MA 02115. E-mail address for E. Losina: elosina@partners.org.
authors.forename: Elena
authors.initials: E
authors.lastname: Losina
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000191:economics*; D003198:Computer Simulation; D003362:Cost-Benefit Analysis; D006801:Humans; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000191:economics / Q000601:surgery*; D010027:Osteotomy / Q000191:economics; D011475:Prosthesis Failure; D011788:Quality of Life; D019057:Quality-Adjusted Life Years; D013977:Tibia / Q000601:surgery