Edward Quigley, M.S.
Freeman Miller, M..D., Patrick Castagno, M.S., James Richards, Ph.D.,
Nancy Lennon, P.T., Tim Niiler, M.S.
The Alfred I. duPont Institute
1600 Rockland Road
Wilmington, Delaware 19803
INTRODUCTION: Understanding the variations in gait parameters which are utilized to make clinical treatment decisions is important. These variations have not been quantified in children with cerebral palsy compared to their peers, although, clinical decisions are made with the presumption that variations are minimal. A review of literature relative to the repeatability of gait analysis measurements yields very little information. An initial report investigated between and within day variability of gait kinematics but used only 2 normal adults (Winter, 1984). Additional research involving 40 normal adults has revealed extremely reproducible kinematic results over 3 visits (Kadaba et al., 1989). The only attempt to investigate variability and reproducibility in children with cerebral palsy over multiple visits concentrated on temporal- spatial characteristics and force plate recordings (Kirkpatrick, et al., 1994). Subsequently, this study demonstrated highly reproducible results for within each subject and between multiple test days. The specific goal of this study is to compare variations in walking gait kinematics between children with cerebral palsy and age matched normal peers.
MATERIALS AND METHODS: Ten children, five with CP and five non-disabled age matched peers volunteered for this study. Subjects ranged in age from six to sixteen, with a mean age of 9.6 years. Video data was obtained using a high-resolution 6 camera Motion Analysis system. Trials were collected for a 5 second duration at 60 Hz. Patients were asked to walk at a self-selected speed for three trials per visit on 5 separate visits. Project-specific software was created to calculate bilateral 3-dimensional joint kinematics for the ankle, knee, and hip using a modified Helen Hayes marker set. Data from each subject consisted of 3 gait cycles bilaterally for each visit. Gait cycles were dilated to 100 samples. Intraclass correlation coefficient profiles (ICC) were created within and between visits to determine the reliability of the kinematic data for each joint. The ICC profiles, as seen in figure 1, were generated for each sample during the gait cycle across all visits for each subject for the between visit comparison and for each sample during the gait cycle across each subject's 3 trials within each visit. This method was used to determine reliability of joint kinematic data.
Figure 1. Comparison of normal group knee motion across 5 visits and ICC profile. RESULTS: The ICC profile on preliminary data indicated that the seven joint actions (table 1) are highly reliable from step to step within the same visit (three steps). Small differences are noted between the reliability of kinematic data for children with CP when compared to normal children within each visit. Between five visit ICC profile (table 2) for both groups indicated an overall decrease in reliability of kinematic data from the within visit comparisons. On the average, the children with CP demonstrated greater consistency in their kinematic patterns between visits than their counterparts without CP.
CONCLUSIONS: The concept of variation within specific gait parameters from one day to the next and within each gait cycle has been recognized. Some have speculated that children with CP are much more variable in their Gait patterns from one step to the next as compared to normal. Although preliminary (3 subjects/group), these results suggest that routine gait analysis of joint motions as measured through high-speed video graphic techniques are reasonably reproducible between and within each visit.
Kadaba, M.P., et. al., journal of Orthopedic Res. 7:849-860, 1989.
Kirkpatrick, M., et. al., journal of Pediatric Orthopedics 14:705-708, 1989.
Winter, D.A., et. al., Human Movement Science, 3:51-76, 1984.
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