title: Clinically important body weight gain following knee arthroplasty: a five-year comparative cohort study.
abstract: OBJECTIVE
  The impact of knee arthroplasty on body weight has not been fully explored. Clinically important weight gain following knee arthroplasty would pose potentially important health risks.
  
  
  METHODS
  We used one of the largest US-based knee arthroplasty registries and a population-based control sample from the same geographic region to determine whether knee arthroplasty increases the risk of clinically important weight gain of ≥5% of baseline body weight over a 5-year postoperative period.
  
  
  RESULTS
  Of the persons in the knee arthroplasty sample, 30.0% gained ≥5% of baseline body weight 5 years following surgery as compared to 19.7% of the control sample. The multivariable-adjusted (age, sex, body mass index, education, comorbidity, and presurgical weight change) odds ratio (OR) was 1.6 (95% confidence interval [95% CI] 1.2-2.2) in persons with knee arthroplasty as compared to the control sample. Additional arthroplasty procedures during followup further increased the risk for weight gain (OR 2.1, 95% CI 1.4-3.1) relative to the control sample. Specifically, among patients with knee arthroplasty, younger patients and those who lost greater amounts of weight in the 5-year preoperative period were at greater risk for clinically important weight gain.
  
  
  CONCLUSIONS
  Patients who undergo knee arthroplasty are at an increased risk of clinically important weight gain following surgery. The findings potentially have broad implications to multiple members of the health care team. Future research should develop weight loss/maintenance interventions particularly for younger patients who have lost a substantial amount of weight prior to surgery, as they are most at risk for substantial postsurgical weight gain.
authors.affiliation: Virginia Commonwealth University, Departments of Physical Therapy and Orthopaedic Surgery, PO Box 980224, Richmond, VA 23298-0224, USA. dlriddle@vcu.edu
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Riddle
authors.forename: Jasvinder A
authors.initials: JA
authors.lastname: Singh
authors.forename: William S
authors.initials: WS
authors.lastname: Harmsen
authors.forename: Cathy D
authors.initials: CD
authors.lastname: Schleck
authors.forename: David G
authors.initials: DG
authors.lastname: Lewallen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000639:trends*; D001835:Body Weight / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012042:Registries; D012307:Risk Factors; D015430:Weight Gain / Q000502:physiology*