title: Computerized biofeedback knee goniometer: acceptance and effect on exercise behavior in post-total knee arthroplasty rehabilitation.
abstract: OBJECTIVE
  To assess device accuracy, patient acceptance, and effect of a computerized biofeedback knee goniometer (CBG), on patients' compliance with active range of motion (AROM) exercises after total knee arthroplasty (TKA).
  
  
  METHODS
  Two-stage study: measurement validation on asymptomatic controls and an unblinded, multiple crossover trial.
  
  
  METHODS
  Inpatient rehabilitation.
  
  
  METHODS
  Asymptomatic controls (n=14) and post-TKA inpatients (n=11).
  
  
  METHODS
  For measurement validation, CBG-angle measurements were compared with manual, clinician-obtained angles. To assess motivational effect, the CBG was worn after TKA; on alternating days, it either monitored AROM silently (no feedback) or provided audiovisual feedback about reaching preset range of motion (ROM) goals and prompted the patients to exercise when idle.
  
  
  METHODS
  To assess accuracy, the device's readings were compared with manual measurements. Patient satisfaction was determined by a self-report questionnaire; exercise compliance was assessed by calculating activity rate and stratified interactivity intervals.
  
  
  RESULTS
  CBG readings reproduced clinician measurements reliably between 0 degrees and 100 degrees (eta(2)=98.5%). Auditory feedback was more helpful than visual feedback for motivating exercise. During feedback-on days, the mean total activity rate +/- standard deviation was 15.1+/-10.9 activity counts per hour, and the interactivity interval was 6.7+/-5.7 minutes. The activity rate was higher on feedback-off days-22.5+/-11.1 counts/hour (P=.11)-and the mean interactivity interval was 3.6+/-2.7 minutes (P=.07).
  
  
  CONCLUSIONS
  The CBG provided reliable, unbiased estimates of clinician measurements of joint angle within the range of 0 degrees to 100 degrees. The CBG was accepted well by most patients. Surprisingly, slightly more ROM activity was noted during feedback-off days than feedback-on days.
authors.affiliation: Rehabilitation Institute of Chicago, 345 E. Superior Street, Rm. 1124, Chicago, IL 60611, USA. tkuiken@rehabchicago.org
authors.forename: Todd A
authors.initials: TA
authors.lastname: Kuiken
authors.forename: Hagay
authors.initials: H
authors.lastname: Amir
authors.forename: Robert A
authors.initials: RA
authors.lastname: Scheidt
mesh_terms: D000704:Analysis of Variance; D019645:Arthroplasty, Replacement, Knee / Q000534:rehabilitation*; D001294:Attitude to Health; D001676:Biofeedback, Psychology / Q000295:instrumentation* / Q000379:methods; D018592:Cross-Over Studies; D005081:Exercise Therapy / Q000295:instrumentation*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance; D017060:Patient Satisfaction; D016059:Range of Motion, Articular / Q000502:physiology; D013813:Therapy, Computer-Assisted; D014481:United States