title: Validity and sensitivity of the longitudinal asymmetry index to detect gait asymmetry using Microsoft Kinect data.
abstract: Gait asymmetry information is a key point in disease screening and follow-up. Constant Relative Phase (CRP) has been used to quantify within-stride asymmetry index, which requires noise-free and accurate motion capture, which is difficult to obtain in clinical settings. This study explores a new index, the Longitudinal Asymmetry Index (ILong) which is derived using data from a low-cost depth camera (Kinect). ILong is based on depth images averaged over several gait cycles, rather than derived joint positions or angles. This study aims to evaluate (1) the validity of CRP computed with Kinect, (2) the validity and sensitivity of ILong for measuring gait asymmetry based solely on data provided by a depth camera, (3) the clinical applicability of a posteriorly mounted camera system to avoid occlusion caused by the standard front-fitted treadmill consoles and (4) the number of strides needed to reliably calculate ILong. The gait of 15 subjects was recorded concurrently with a marker-based system (MBS) and Kinect, and asymmetry was artificially reproduced by introducing a 5cm sole attached to one foot. CRP computed with Kinect was not reliable. ILong detected this disturbed gait reliably and could be computed from a posteriorly placed Kinect without loss of validity. A minimum of five strides was needed to achieve a correlation coefficient of 0.9 between standard MBS and low-cost depth camera based ILong. ILong provides a clinically pragmatic method for measuring gait asymmetry, with application for improved patient care through enhanced disease, screening, diagnosis and monitoring.
authors: MSK Lab, Department of Surgery and Cancer, Imperial College London, Charing Cross Hospital, W6 8RP, London, United Kingdom. Electronic address: e.auvinet@imperial.ac.uk.
authors: E
authors: E
authors: Auvinet
authors: M2S Laboratory, University Rennes 2, ENS Rennes, Avenue Robert Schuman, 35170 Bruz, France; INRIA, MimeTIC team, Campus Universitaire de Beaulieu, 35042 Rennes, France.
authors: F
authors: F
authors: Multon
authors: MSK Lab, Department of Surgery and Cancer, Imperial College London, Charing Cross Hospital, W6 8RP, London, United Kingdom.
authors: V
authors: V
authors: Manning
authors: Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal H3C 3J7, QC, Canada.
authors: J
authors: J
authors: Meunier
authors: MSK Lab, Department of Surgery and Cancer, Imperial College London, Charing Cross Hospital, W6 8RP, London, United Kingdom.
authors: J P
authors: JP
authors: Cobb
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005080:Exercise Test; D005260:Female; D005684:Gait; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D016138:Walking
keywords: CRP; Gait analysis; Gait asymmetry; Kinect; Sensitivity analysis