title: Knee arthroplasty: a cross-sectional study assessing energy expenditure and activity.
abstract: BACKGROUND
  What has been missing from current assessment tools post knee arthroplasty is a means by which a patient's mobility and activity levels can be objectively measured over time in a real world setting. The Intelligent Device for Energy Expenditure and Activity (Minisun, Fresno, USA) (IDEEA) is one such device that meets these criteria. It quantifies activity by measuring energy expenditure and records the type of activity performed. The purposes of this study were to (i) determine if there were differences in energy expenditure in different groups of patients at various time points pre- and post-surgery and (ii) determine the correlations between energy expenditure and each of the subjective International Knee Documentation Committee (IKDC), Oxford and Tegner scoring systems.
  
  
  METHODS
  Sixty-five total knee arthroplasty (TKA) patients were recruited into a cross-sectional study to collect energy expenditure and activity data using the IDEEA. Data were collected preoperatively and post-operatively at 6-week, 3-month, 6-month and 12-month time intervals.
  
  
  RESULTS
  Energy expenditure and type of activity did not significantly change over the five recording periods. The patients spent <5% of the recording time walking, stepping or in transitions between movements. Energy expenditure showed a low to moderate correlation with the subjective IKDC, Oxford and Tegner questionnaires.
  
  
  CONCLUSIONS
  Current evaluation questionnaires may not accurately record activity levels and TKA patients spend less time walking than the normal population. We believe the IDEEA is an effective tool for objectively measuring activity and energy expenditure following knee arthroplasty.
authors.affiliation: Brisbane Orthopaedic & Sports Medicine Centre, Brisbane, Queensland, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Hayes
authors.forename: Mark C
authors.initials: MC
authors.lastname: Watts
authors.forename: Libby J
authors.initials: LJ
authors.lastname: Anderson
authors.forename: William R
authors.initials: WR
authors.lastname: Walsh
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000534:rehabilitation*; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D009043:Motor Activity; D011795:Surveys and Questionnaires