title: The reliability and validity of assessment of sagittal plane deviations in children who have spastic diplegia.
abstract: OBJECTIVE
  To assess the reliability and validity of a newly described classification of sagittal plane alignment in spastic diplegic gait.
  
  
  METHODS
  Twenty split-screen videos of children with spastic diplegia, Gross Motor Function Classification System levels I to III, were viewed on 2 occasions, 6 weeks apart, by 5 raters. The sagittal plane alignments of the right and left lower limbs in gait were classified separately as true equinus, jump knee, apparent equinus, or crouch, based on the published classification. A fifth category, nonclassifiable, was used if classification was not possible. We then used sagittal plane kinematic data to confirm the classification for each subject and these were compared with rater classification scores, which used the video information only.
  
  
  METHODS
  Tertiary-level children's hospital.
  
  
  METHODS
  Three pediatric orthopedic surgeons and 2 pediatric orthopedic residents.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Gait classification scores derived from visual observation were compared among and within raters. The gait classification scores derived from visual observation were compared with the scores derived from sagittal plane kinematic data to assess validity.
  
  
  RESULTS
  A moderate correlation was found among the 5 raters within each session, with an interrater weighted kappa score of .45 in session 1 and .49 in session 2. The intrarater, weighted kappa scores showed a moderate to substantial level of agreement between sessions, ranging from .50 to .68. The classification scores of individual raters had moderate validity when compared with classifications derived from the sagittal plane kinematic data. However, there was a substantial level of agreement between the consensus opinion and the classification obtained using the kinematic data as well as the video recordings (weighted kappa=0.8).
  
  
  CONCLUSIONS
  This classification has only moderate reliability and validity when a single experienced rater views the 2-dimensional gait videos. However, the consensus opinion derived from the scores of 5 raters considerably improves the validity of the assessment.
authors.affiliation: Department of Surgery, University of Auckland, Auckland, New Zealand. s.stott@auckland.ac.nz
authors.forename: N Susan
authors.initials: NS
authors.lastname: Stott
authors.forename: W Guy
authors.initials: WG
authors.lastname: Atherton
authors.forename: Anna H
authors.initials: AH
authors.lastname: Mackey
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Galley
authors.forename: Richard O
authors.initials: RO
authors.lastname: Nicol
authors.forename: Stewart J
authors.initials: SJ
authors.lastname: Walsh
mesh_terms: D001696:Biomechanical Phenomena; D002547:Cerebral Palsy / Q000175:diagnosis* / Q000534:rehabilitation*; D002648:Child; D004185:Disability Evaluation; D005260:Female; D005684:Gait; D006801:Humans; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D014743:Videotape Recording