title: Stability of serial range-of-motion measurements of the lower extremities in children with cerebral palsy: can we do better?
abstract: BACKGROUND
  Serial joint range-of-motion (ROM) measurements are an important component of assessments for children with cerebral palsy. Most research has studied ROM stability using group data. Examination of longitudinal intraindividual measures may provide more clinically relevant information about measurement variability.
  
  
  OBJECTIVE
  The aim of this study was to examine the stability of intraindividual longitudinal measurements of hip abduction (ABD), popliteal angle (POP), and ankle dorsiflexion (ADF) ROM measures of children with cerebral palsy.
  
  
  METHODS
  Secondary data analyses were performed.
  
  
  METHODS
  The stability patterns of individual serial measurements of ABD, POP, and ADF from 85 children (mean age=3.8 years, SD=1.4) collected at baseline (T1), 3 months (T2), 6 months (T3), and 9 months (T4) were examined using T1 as the anchor and bandwidths of ±15 degrees (ABD and POP) and ±10 degrees (ADF) as acceptable variability. Frequencies of stability categories (0°-5°, 5.1°-10°, 10.1°-15°, and >15°) were calculated. Patterns of stability across the 4 time periods also were examined. Group means (T1-T4) were compared using repeated-measures analysis of variance.
  
  
  RESULTS
  No significant differences in group means were found except for ABD. Stability patterns revealed that 43.3% to 69.5% of joint measurements were stable with T1 measurements across all 3 subsequent measurements. Stability category frequencies showed that many measurements (ABD=17%, POP=29.9%, and ADF=37.1%) went outside the variability bandwidths even though 39% or more of joint measurements had a change of 5 degrees or less over time.
  
  
  CONCLUSIONS
  Measurement error and true measurement variability cannot be disentangled. The results cannot be extrapolated to other joint ROMs.
  
  
  CONCLUSIONS
  Individual ROM serial measurement exhibits more variability than group data. Range-of-motion data must be interpreted with caution clinically and efforts made to ensure standardization of data collection methods.
authors.affiliation: J. Darrah, PT, PhD, Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, 2-50 Corbett Hall, Edmonton, Alberta, Canada T6E 2S7. johanna.darrah@ualberta.ca.
authors.forename: Johanna
authors.initials: J
authors.lastname: Darrah
authors.affiliation: L. Wiart, PT, PhD, Clinical Support, Glenrose Rehabilitation Hospital, Edmonton, Alberta, Canada, and Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta.
authors.forename: Lesley
authors.initials: L
authors.lastname: Wiart
authors.affiliation: J.W. Gorter, MD, PhD, FRCPC, Department of Pediatrics, CanChild Centre for Childhood Disability Research, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Jan Willem
authors.initials: JW
authors.lastname: Gorter
authors.affiliation: M. Law, PhD, OTReg(ON), School of Rehabilitation Science and CanChild Centre for Childhood Disability Research, McMaster University.
authors.forename: Mary
authors.initials: M
authors.lastname: Law
mesh_terms: D000843:Ankle Joint / Q000503:physiopathology; D053587:Arthrometry, Articular; D002547:Cerebral Palsy / Q000503:physiopathology*; D002675:Child, Preschool; D005260:Female; D006621:Hip Joint / Q000503:physiopathology; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D008137:Longitudinal Studies; D008297:Male; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results