Reliability of footprint geometric and plantar loading measurements in children using the Emed(®) M system

This study investigated the between-day reliability of footprint geometric and plantar loading measurements on children utilising the Emed(®) M pressure measurement device. Bilateral footprints (static and dynamic) and foot loading measurements using the two-step gait method were collected on 21 children two days apart (age = 9.9 ± 1.8 years; mass = 34.6 ± 8.9 kg; height = 1.38 ± 0.12 m). Static and dynamic footprint geometric (lengths, widths and angles) and dynamic loading (pressures, forces, contact areas and contact time) parameters were compared. Intraclass correlation coefficients of static geometric parameters were varied (0.19-0.96), while superior results were achieved with dynamic geometric (0.66-0.98) and loading variables (0.52-0.94), with the exception of left contact time (0.37). Standard error of measurement recorded small absolute disparity for all geometric (length = 0.1-0.3 cm; arch index = 0.00-0.01; subarch angle = 0.6-6.2°; left/right foot progression angle = 0.5°/0.7°) and loading (peak pressure = 2.3-16.2 kPa; maximum force = 0.3-3.0%; total contact area = 0.28-0.49 cm(2); % contact area = 0.1-0.6%; contact time = 32-79 ms) variables. Coefficient of variation displayed widest spread for static geometry (1.1-27.6%) followed by dynamic geometry (0.8-22.5%) and smallest spread for loading (1.3-16.8%) parameters. Limits of agreement (95%) were narrower in dynamic than static geometric parameters. Overall, the reliability of most dynamic geometric and loading parameters was good and excellent. Static electronic footprint measurements on children are not recommended due to their light body mass which results in incomplete footprints.