Comparison of kinematic and pressure measurement reference methods used in gait event detection

Abstract

Purpose: A variety of methods have been proposed for detection of initial contact (IC) and foot off (FO) and some comparative analysis is reported in the literature. Pressure measurement insoles and kinematic systems are often part of footwear analysis. Although gait event detection algorithms using these systems have been proposed and evaluated against kinetic data (KN) from force platforms (typically used as a ‘gold standard’), they have not been compared directly. The objective of this work was to undertake this comparison using the same volunteer dataset and test conditions.

Methods: Data from 10 healthy adults walking at self-selected normal speed were collected. Two kinematic algorithms (one using a fixed threshold, KM, and the other using high pass-filtering, HPA) and one algorithm using pressure measurement data from an insole (Contact Area Detection, AD) were tested and compared with the detection provided by KN. All data were synchronised and sampled at 200 Hz. Six basic spatio-temporal parameters were also calculated.

Results: The absolute mean difference (AMD) in event detection between the three methods and KN was below 25 ms. However, the methods presented tendencies to detect events earlier or later than KN and this influenced the AMD between the methods, which increased to 47 ms for IC detection between HPA and AD. The spatio-temporal parameters showed no statistically significant differences between AD and KM, but differences reached statistical significance between AD and HPA.

Conclusion: It is possible to compare gait events and basic spatio-temporal parameters detected using data from pressure measurement insoles and kinematic algorithms; however the kinematic algorithm used will influence the results. Hence the comparison of findings from alternative detection methods is an important issue for which information about the behaviour of the method used is required.

Keywords:

• gait event detection
• pressure detection
• kinetic
• kinematic
• initial contact
• foot off

Acknowledgements

The authors would like to acknowledge the time and support of the volunteers who took part in this study.