title: The Influence of Obesity on the Outcome of TKR: Can the Impact of Obesity be justified from the Viewpoint of the Overall Health Care System?
abstract: BACKGROUND
  There is controversy in the literature regarding the justification of performing total knee replacement (TKR) in obese patients in view of their increased risk of poor outcomes and how those poorer outcomes impact the health care system overall.
  
  
  OBJECTIVE
  Is TKR justifiable in the obese patient? Can the negative impact of continuing to perform TKR in the obese be quantified?
  
  
  METHODS
  A Cochrane Library, PubMed (MEDLINE), and Google Scholar search related to the justification of TKR in the obese patient and its impact on the health care system was analyzed. The main criteria for selection were that the articles were focused in the aforementioned questions.
  
  
  RESULTS
  Two thousand one hundred seventy-three articles were found, but only 50 were selected and reviewed because they were focused on the questions of this paper. Although some articles (with low grade of evidence) did not find that obesity adversely affected the outcome of TKR, most of them found that obesity adversely affected the results of TKR. Regarding complications rates and survival rates, obesity has shown to have a negative influence on outcome after TKR. The improvements in patient-reported outcome measures, however, were similar irrespective of body mass index. Regarding the impact of TKR in obese patients, an extra cost of US$3,050 has been reported per patient. Considering that 50% of the US population is obese and that 600,000 TKRs are implanted per year, the impact for the US health system could be as much as 915 million dollars (300,000 × 3,050).
  
  
  CONCLUSIONS
  TKR in obese patients may be justifiable because the functional improvements appear equivalent to those of patients with a lower BMI. However, in obese patients, the risk of complications is higher and the prosthetic survival is lower. Moreover, TKR in obese patients has a huge impact on the health system which should be considered.
authors: Department of Orthopaedic Surgery, La Paz University Hospital, Paseo de la Castellana 261, 28046 Madrid, Spain ; Department of Orthopaedic Surgery, School of Medicine, Universidad Autónoma de Madrid, Madrid, Spain.
authors: E Carlos
authors: EC
authors: Rodriguez-Merchan
keywords: economical impact; health system; obesity; total knee replacement