RESEARCH REPORT PLATFORM PRESENTATION

SINE WAVE ANALYSIS OF WALKING PATTERNS IN CHILDREN DEMONSTRATES CHANGES WITH MATURITY OF GAIT. Alderson L^1,2, Watson T¹, Main E^2,3; ¹University of Hertfordshire, Hatfield, UK. ²Physiotherapy Department, Great Ormond Street Hospital, London, UK. ³Institute of Child Health, University College London, UK

PURPOSE: Walking on even surfaces generates a regular pattern of weight shift. As the body moves forward the Centre of Pressure (COP) follows a sinusoidal pattern, which has potential to describe both normal and abnormal gait. The GAITRite walkway provides raw COP data and preliminary results from a novel analysis of this data (comparing the regularity of the COP walking pattern to a normal sine-wave), show promise for clinical applications. In preparation for using this technique in children with balance difficulties and irregular walking patterns, this study aimed to describe changes during growth using a) the characteristics of the sine-wave during gait, and b) the variation between the predicted sine-wave for each child and actual COP data. RELEVANCE: There are few appropriate clinical outcome measures that provide quantitative information about dynamic walking balance in children. Temporal and spatial (TS) outcomes like velocity or step length do not provide sufficient depth of information to describe control of movement when children have walking and balance difficulties. PARTICIPANTS: 137 children aged 4-14yrs with no neurological or musculoskeletal conditions were recruited from local schools. The first ten children in each year group who returned signed parental consent were included. METHODS: The children walked across the walkway (5m x 1m) three times at each of three speeds: preferred, fast and slow. Linear regression was used to find the best fit sine-wave for each speed. The wavelength (represented by two step lengths) was used to fit the model, and the amplitude (step width) and the gradient (direction of line of progression) for each walk were computed. The fit of the sine-wave (%) and the residual error (cm) were calculated to provide absolute and relative measures of variation. ANALYSIS: Children were stratified into five age groups 4-5yrs; 6-7yrs; 8-9yrs; 10-11yrs; 12-14yrs. A one-way ANOVA was used to explore age group effects. Planned contrasts were completed to evaluate differences between specific age groups. RESULTS: The fit of the model, and residual error both had significant age effects at all speeds (p ≤ 0.01). The fit increased with age from 80 to 90%, and residual error decreased from 3 to 1.5cm. Both had greatest differences between 4-9 years. The wavelength showed a significant increase with age (p ≤ 0.02). The amplitude had significant increase with age at slow speed only (p < 0.001). The effect of age on gradient was not significant. CONCLUSIONS: Regression analysis was successfully used to fit a sine-wave to the GAITRite COP data. This demonstrates that during development, wavelength (step length) increases, and the fit of a sine-wave model improves with a reduced error. This unique application of a sine-wave analysis suggests children reduce variability of their walking as they grow, improving efficiency. This analysis has enormous potential to detect subtle changes in the regularity of the walking pattern in children of different ages and further work incorporating clinical populations is being undertaken to confirm its clinical value. IMPLICATIONS: The GAITRite is a relatively inexpensive and simple tool that can produce accurate TS and COP data. Sine-wave regression analysis enables clinicians to describe the uniformity of the walking pattern. KEYWORDS: Walking, Centre of Pressure, Sine-wave analysis. FUNDING ACKNOWLEDGEMENTS: This study was completed as part of a PhD project that was funded by the Health Foundation and Great Ormond Street Hospital. CONTACT: alderl@gosh.nhs.uk

ETHICS COMMITTEE: Barnet and Enfield Research and Ethics Committee, London, UK.