title: Does body mass index affect the outcome of unicompartmental knee replacement?
abstract: BACKGROUND
  Obesity is considered to be a contraindication for unicompartmental knee replacement (UKR). The aim was to study the impact of BMI on failure rate and clinical outcome of the Oxford mobile bearing UKR.
  
  
  METHODS
  Two thousand four hundred and thirty-eight medial Oxford UKRs were studied prospectively and divided into groups: BMI<25 (n=378), BMI 25 to <30 (n=856), BMI 30 to <35 (n=712), BMI 35 to <40 (n=286), and BMI 40 to <45 (n=126) and BMI≥45 (n=80).
  
  
  RESULTS
  There was no significant difference in survival rate between groups. At a mean follow-up of 5years (range 1-12years) there was no significant difference in the Objective American Knee Society Score between groups. There was a significant (p<0.01) trend with the Oxford Knee Score (OKS) and Functional American Knee Society Scores decreasing with increasing BMI. As there was an opposite trend (p<0.01) in pre-operative OKS, the change in OKS increased with increasing BMI (p=0.048). The mean age at surgery was significantly (p<0.01) lower in patients with higher BMI.
  
  
  CONCLUSIONS
  Increasing BMI was not associated with an increasing failure rate. It was also not associated with a decreasing benefit from the operation. Therefore, a high BMI should not be considered a contra-indication to mobile bearing UKR.
  
  
  METHODS
  IV.
authors.affiliation: The Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Headington, Oxford, UK; The Nuffield Orthopaedic Centre, Headington, Oxford, UK. Electronic address: david.murray@ndorms.ox.ac.uk.
authors.forename: D W
authors.initials: DW
authors.lastname: Murray
authors.forename: H
authors.initials: H
authors.lastname: Pandit
authors.forename: J S
authors.initials: JS
authors.lastname: Weston-Simons
authors.forename: C
authors.initials: C
authors.lastname: Jenkins
authors.forename: H S
authors.initials: HS
authors.lastname: Gill
authors.forename: A V
authors.initials: AV
authors.lastname: Lombardi
authors.forename: C A F
authors.initials: CA
authors.lastname: Dodd
authors.forename: K R
authors.initials: KR
authors.lastname: Berend
mesh_terms: D000328:Adult; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods*; D015992:Body Mass Index; D015331:Cohort Studies; D016208:Databases, Factual; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000009:adverse effects / Q000379:methods; D009765:Obesity / Q000175:diagnosis* / Q000453:epidemiology; D011474:Prosthesis Design; D011475:Prosthesis Failure / Q000639:trends*; D020127:Recovery of Function; D012189:Retrospective Studies; D018570:Risk Assessment; D016896:Treatment Outcome
keywords: Obesity; Outcomes; Unicompartmental knee replacement