title: Hip and knee arthroplasty implants contraindicated in obesity.
abstract: BACKGROUND
  High patient weight is a risk factor for mechanical implant failure and some manufacturers list obesity as a contraindication for implant use. We reviewed data from the 2012-2013 UK National Joint Registry to determine whether surgical practice reflects these manufacturer recommendations.
  
  
  METHODS
  The product literature for the most commonly used hip and knee implants was reviewed for recommendations against use in obese patients (body mass index [BMI] ≥ 30kg/m(2)). The total number of obese patients undergoing hip and knee arthroplasty was calculated, as was the proportion receiving implants against manufacturer recommendations.
  
  
  RESULTS
  Out of 200,054 patient records, 147,691 (74%) had a recorded BMI. The mean BMI for patients undergoing primary total hip arthroplasty was 29kg/m(2), compared with 31kg/m(2) for total knee arthroplasty. Of the 25 components reviewed, 5 listed obesity as a contraindication or recommended against implant use in obese patients. A total of 10,745 patients (16% of all obese patients) received implants against manufacturer recommendations.
  
  
  CONCLUSIONS
  A high proportion of patients are receiving implants against manufacturer recommendations. However, there are limitations to using BMI for stratifying risk of implant fatigue failure and manufacturers should therefore provide more detailed guidelines on size specific implant load limits to facilitate surgical decisions.
authors.affiliation: St George's University Hospitals NHS Foundation Trust , UK.
authors.forename: J D
authors.initials: JD
authors.lastname: Craik
authors.affiliation: St George's University Hospitals NHS Foundation Trust , UK.
authors.forename: M D
authors.initials: MD
authors.lastname: Bircher
authors.affiliation: St George's University Hospitals NHS Foundation Trust , UK.
authors.forename: M
authors.initials: M
authors.lastname: Rickman
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects; D015992:Body Mass Index; D000075202:Contraindications; D006622:Hip Prosthesis; D006801:Humans; D007720:Knee Prosthesis; D009765:Obesity / Q000150:complications* / Q000453:epidemiology; D011183:Postoperative Complications / Q000453:epidemiology* / Q000209:etiology*; D011475:Prosthesis Failure; D012189:Retrospective Studies; D012307:Risk Factors
keywords: Arthroplasty; Hip; Implant; Knee; Obesity; Prosthesis