Abstract
The evaluation of local divergence exponent (LDE) has been proposed as a common gait stability measure in people with multiple sclerosis (PwMS). However, differences in methods of determining LDE may lead to different results. Therefore, the purpose of the current study was to determine the effect of different sensor locations and LDE measures on the sensitivity to discriminate PwMS. To accomplish this, 86 PwMS and 30 healthy participants were instructed to complete a six-minute walk wearing inertial sensors attached to the foot, trunk and lumbar spine. Due to possible fatigue effects, the LDE short (~50% of stride) and very short (~5% of stride) were calculated for the remaining first, middle and last 30 strides. The effect of group (PwMS vs. healthy participants) and time (begin, mid, end) and the effect of Expanded Disability Status Scale (EDSS) and time were assessed with linear random intercepts models. We found that perturbations seem to be better compensated in healthy participants on a longer time scale based on trunk movements and on a shorter time scale (almost instantaneously) according to the foot kinematics. Therefore, we suggest to consider both sensor location and time scale of LDE when calculating local gait stability in PwMS.
Highlights
Gait analysis is frequently utilized in patients with multiple sclerosis (PwMS)
The purpose of the current study was to determine the effect of different sensor locations on the sensitivity to discriminate PwMS with a varying level of disability based on local gait stability (LDE)
Perturbations seem to be better compensated in the healthy comparison group on a longer time scale based on trunk movements and on a shorter time scale according to the foot kinematics
Summary
Gait analysis is frequently utilized in patients with multiple sclerosis (PwMS). To estimate gait stability or the risk of falling in PwMS, different measures have been used.Besides the calculation of gait variability (e.g., [1,2,3]) or margin of stability (e.g., [4]), the evaluation of local dynamic stability (operationalized through the local divergence exponent, LDE) has been proposed as a common gait stability measure (e.g., [5,6,7,8]).In particular, local dynamic stability is an approach to evaluate the ability of the locomotor system to recover from small perturbations that occur during walking [9]. To estimate gait stability or the risk of falling in PwMS, different measures have been used. Besides the calculation of gait variability (e.g., [1,2,3]) or margin of stability (e.g., [4]), the evaluation of local dynamic stability (operationalized through the local divergence exponent, LDE) has been proposed as a common gait stability measure (e.g., [5,6,7,8]). Local dynamic stability is an approach to evaluate the ability of the locomotor system to recover from small perturbations that occur during walking [9]. LDE was proposed as a measure to rate fall risk in PwMS [8,10]. Previous studies analyzing the LDE in PwMS have shown that e.g., the LDE is greater (lower stability) in PwMS than in healthy participants [2,6]
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