Kinematic Validation of a Multi-Kinect v2 Instrumented 10-Meter Walkway for Quantitative Gait Assessments.

Daphne J Geerse,Melvyn Roerdink,Bert H Coolen,Alfonso Fasano

doi:10.1371/journal.pone.0139913

Daphne J Geerse, Melvyn Roerdink + Show 2 more

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https://doi.org/10.1371/journal.pone.0139913

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Abstract

Walking ability is frequently assessed with the 10-meter walking test (10MWT), which may be instrumented with multiple Kinect v2 sensors to complement the typical stopwatch-based time to walk 10 meters with quantitative gait information derived from Kinect’s 3D body point’s time series. The current study aimed to evaluate a multi-Kinect v2 set-up for quantitative gait assessments during the 10MWT against a gold-standard motion-registration system by determining between-systems agreement for body point’s time series, spatiotemporal gait parameters and the time to walk 10 meters. To this end, the 10MWT was conducted at comfortable and maximum walking speed, while 3D full-body kinematics was concurrently recorded with the multi-Kinect v2 set-up and the Optotrak motion-registration system (i.e., the gold standard). Between-systems agreement for body point’s time series was assessed with the intraclass correlation coefficient (ICC). Between-systems agreement was similarly determined for the gait parameters’ walking speed, cadence, step length, stride length, step width, step time, stride time (all obtained for the intermediate 6 meters) and the time to walk 10 meters, complemented by Bland-Altman’s bias and limits of agreement. Body point’s time series agreed well between the motion-registration systems, particularly so for body points in motion. For both comfortable and maximum walking speeds, the between-systems agreement for the time to walk 10 meters and all gait parameters except step width was high (ICC ≥ 0.888), with negligible biases and narrow limits of agreement. Hence, body point’s time series and gait parameters obtained with a multi-Kinect v2 set-up match well with those derived with a gold standard in 3D measurement accuracy. Future studies are recommended to test the clinical utility of the multi-Kinect v2 set-up to automate 10MWT assessments, thereby complementing the time to walk 10 meters with reliable spatiotemporal gait parameters obtained objectively in a quick, unobtrusive and patient-friendly manner.

Highlights

Walking speed is associated with falls [1,2,3], adverse events [4,5] and life expectancy [6] in older adults
We evaluated a multi-Kinect v2 set-up for quantitative gait assessment during the 10-meter walking test (10MWT) by determining between-systems agreement for body point’s time series, for spatiotemporal gait parameters and for the time to walk 10 meters
Body point’s time series obtained with a multi-Kinect v2 set-up match well with those derived with a gold standard in 3D measurement accuracy, so for body points in motion

Summary

Introduction

Walking speed is associated with falls [1,2,3], adverse events [4,5] and life expectancy [6] in older adults. Even the best motion-registration systems yield limitations when conducting quantitative gait assessments in clinical settings (e.g., costs, patient-preparation time, calibration procedures, marker occlusion, and delays in availability of results [7]). The development of 3D human-pose estimation software, using a large and highly varied training dataset of paired depth images and ground truth body parts to train very deep decision forests for efficient and accurate body part recognition [8], was a major undertaking by Microsoft. It successfully eliminated the need for markers and calibration procedures, thereby enabling fast and patient-friendly 3D full-body motion registration (Fig 1). Key differences with the previous Kinect v1 sensor are that the Kinect v2 sensor is a time-of-flight camera with an increased resolution of the depth image, a wider field of view and improved body point tracking [19], possibly leading to improved results

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