Elsevier

Gait & Posture

Volume 38, Issue 2, June 2013, Pages 281-286
Gait & Posture

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

https://doi.org/10.1016/j.gaitpost.2012.11.025Get rights and content

Abstract

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 cm2; % 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.

Highlights

► Dynamic footprint geometric and loading measurements are reliable in children. ► A two-step approach can be adopted for dynamic footprint and pressure measurements. ► Static electronic footprint measurements on children are not recommended.

Introduction

Electronic plantar pressure measurement systems are widely used to assess foot structure and loading pattern in clinical [1], [2] and research [3], [4] settings. As a promising clinical tool, the reliability of such testing devices and protocols employed are of vital importance to guide intervention decision and to evaluate treatment outcomes. In the literature, the reliability of plantar pressure measurement systems is well documented to be good for normal adult population [5], [6], [7], [8], [9]. There is, however, limited information available on children despite the frequent use of foot pressure and footprint analysis on the paediatric population to track foot development and to investigate the association between foot structure and factors such as obesity and plantar fat pad thickness [3], [4], [10], [11].

Generalisation of reliability results from adult to children is inappropriate especially for dynamic test protocols due to their different walking mechanics and that children's gait is still developing [12]. Of the limited reliability studies on children, Oladeji et al. [13] found that the plantar pressure data (contact area, contact time, peak pressure and pressure–time integral) collected using a two-step approach were comparable to those collected using the conventional midgait method. Another study examined the within-day reliability of temporo-spatial gait variables measured using an electronic walkway and the results ranged from poor to excellent [14]. To the best of our knowledge, there are no data on the between-day reliability of footprint geometric and plantar pressure measurements in children. Such information is essential to guide clinicians and researchers on meaningful interpretation of the pressure data acquired on the paediatric population.

Thus, the purpose of this study was to examine the between-day reliability of footprint geometric and plantar loading measurements collected using an electronic plantar measurement device under static and dynamic conditions in primary school children.

Section snippets

Participants

This study was approved by Nanyang Technological University-Institutional Review Board, Singapore. Twenty-one (10 boys) healthy children volunteers were recruited from a local primary school. The mean ± standard deviation (sd) age, body mass and height were 9.9 ± 1.8 years (range: 6.7–12.3 years), 34.6 ± 8.9 kg (range: 21.8–54.5 kg) and 1.38 ± 0.12 m (range: 1.14–1.62 m) respectively. The ethnic distribution was nine Chinese (42.9%), seven Malay (33.3%), two Myanmarese (9.5%), two Filipino (9.5%) and one

Results

Since data were not normally distributed, nonparametric Wilcoxon signed-rank test was employed to observe measurement differences between-day and left/right foot. Although no bilateral differences were observed in the static trials (Table 1), significant differences were found between the left and the right in some dynamic geometric (foot length, foot progression angle, arch index and instep width, Table 2) and loading (PP heel, PP hallux and CA forefoot, Table 3) parameters. Thus, both feet

Discussion

The present study was the first in the literature to assess the between-day reliability of electronic footprint geometric and plantar loading measurements in children. Having considered the potential difficulty for children to control gait velocity without targeting the pressure mat, we measured the static footprint and the two-step dynamic approach, which are easier than the traditional midgait approach. Our results clearly demonstrate that static footprint measurements are invalid for

Conclusion

Dynamic footprint and plantar loading parameters of children using a two-step approach displayed good to excellent reliability (0.61  ICC  0.98) for all geometric and most loading measurements. Static measurements were invalid on children due to incomplete footprint acquisition with the Emed® M system.

Acknowledgements

The authors would like to express their appreciation to Ms. Marabelle Heng, Podiatry Department, Singapore General Hospital for rendering her assistance during the data collection process.

Source of funding: This study was funded by National Institute of Education Academic Research Fund. The funding source did not play a role in the investigation.
Conflict of interest statement

The authors declared that there is no conflict of interest.

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