Reliability and validity of IMU-based foot progression angle measurement under different gait retraining strategies

Master thesis (2022)

Authors

F.C.A. Urbanus Mechanical Engineering

Contributors

Jaap Harlaar Biomechatronics & Human-Machine Control - Mechanical, Maritime and Materials Engineering (mentor)
E. van der Kruk Biomechatronics & Human-Machine Control - Mechanical, Maritime and Materials Engineering (mentor)
Faculty
Mechanical Engineering, Mechanical Engineering
Copyright: © 2022 Francine Urbanus
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Published Date

09-02-2022

Language

English

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Faculty

Mechanical Engineering

Abstract

Background
Gait retraining strategies are used to reduce medial compartment load in people with medial knee osteoarthritis. Two key gait retraining strategies are based on changing the foot progression angle (FPA). The FPA can be measured using a pressure sensitive walkways (PSW), but inertial measurement units (IMUs) are considered more suitable for routine clinical use.
Research question
The purpose of this study was to evaluate the reliability and validity of an IMU system to measure FPA under different gait retraining strategies in a potential clinical setting.
Methods
Twenty healthy participants (14 females, 6 males, mean age=33.7 years, SD=10.3 years) walked along a ± 8.5 m long path using different gait strategies (2x natural gait, 1x toe-out -and 1x toe-in gait) during four 90 second trials. FPA was measured simultaneously with the IMUs (Opal, APDM, Portland, USA) and a PSW (Zeno™ Walkway, ProtoKinetics, Havertown, USA), the latter considered the reference standard.
Results
Test-retest intraclass correlations (ICCs) for the IMUs and the PSW were indicative of good and excellent reliability respectively (IMU ICC=0.89; PSW ICC=0.97). This difference in reliability was also reflected by a higher standard error of measurement (SEM) for IMUs compared to the PSW (IMUs SEM=1.6°, PSW SEM=0.96°). Minimal detectable change (MDC) was 4.5° for the IMUs and 2.7° for the PSW. The repeated measures ANOVA indicated a significant effect of gait type on FPA (p<.001), whereas the measurement instrument did not affect FPA (p=.875). Bland-Altman plots indicate good agreement of both systems for the baseline condition, though the IMUs seem to consistently overestimate the FPA value compared to the PSW. We conclude that IMUs are reliable and valid measurement systems for measuring FPA in natural gait, toe-out and toe-in gait. Differences between the systems are significant for all gait strategies, so systems should not be used interchangeably.
Significance
The IMUs provide a promising tool for clinicians and researchers aiming to quantify FPA for gait retraining.

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