The reliability and validity of assessment of sagittal plane deviations in children who have spastic diplegia.
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.
Stott
N Susan
NS
Department of Surgery, University of Auckland, Auckland, New Zealand. s.stott@auckland.ac.nz
Atherton
W Guy
WG
Mackey
Anna H
AH
Galley
Ian J
IJ
Nicol
Richard O
RO
Walsh
Stewart J
SJ
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