title: Physical activity and risk of revision total knee arthroplasty in individuals with knee osteoarthritis: a matched case-control study.
abstract: OBJECTIVE
  To determine if physical activity was a risk factor for revision arthroplasty after primary total knee arthroplasty (TKA) due to osteoarthritis (OA) within the previous 15 years.
  
  
  METHODS
  This was a matched case-control study. The cases had primary TKA followed by revision arthroplasty. Controls had primary TKA and no revision arthroplasty. Cases and controls were matched for age, sex, number of knees replaced, and date of primary TKA. Standardized telephone interviews were conducted to assess historical leisure activity, occupational activity, and instrumental activities of daily living after primary TKA in metabolic equivalent (MET)-hours per week. Conditional logistic regression was performed to identify the variables that predicted the need for revision arthroplasty.
  
  
  RESULTS
  Seventeen female and 9 male pairs, aged 47 to 85 years, participated. Most of the reported activity was of low impact and low or moderate intensity. Cases reported a median of 44.5 (range 0 to 137) MET-hours of total historical physical activity per week compared with controls' 55.1 (range 0 to 278) MET-hours. Total historical physical activity was not associated with the risk of revision arthroplasty (OR 0.99, 95% CI 0.99-1.01). Participants with primary TKA (controls) consistently reported more MET-hours of leisure and occupational activity than those with revision arthroplasty (cases) regardless of the number of knees replaced or whether or not walking was accounted for.
  
  
  CONCLUSIONS
  This study quantified and described patterns of physical activity in a population with TKA. Physical activity did not appear to be a risk factor for revision arthroplasty. Our results suggest that individuals undergoing primary TKA should be encouraged to remain active after surgery.
authors.affiliation: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA. Dljst4@pitt.edu
authors.forename: Dina L
authors.initials: DL
authors.lastname: Jones
authors.forename: Jane A
authors.initials: JA
authors.lastname: Cauley
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Kriska
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Wisniewski
authors.forename: James J
authors.initials: JJ
authors.lastname: Irrgang
authors.forename: David A
authors.initials: DA
authors.lastname: Heck
authors.forename: C Kent
authors.initials: CK
authors.lastname: Kwoh
authors.forename: Lawrence S
authors.initials: LS
authors.lastname: Crossett
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D020370:Osteoarthritis, Knee / Q000601:surgery*; D011475:Prosthesis Failure; D012086:Reoperation; D012306:Risk