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Knee stiffness estimation in physiological gait


Pfeifer, Serge; Riener, Robert; Vallery, Heike (2014). Knee stiffness estimation in physiological gait. IEEE Engineering in Medicine and Biology Society. Conference Proceedings, 2014:1607-1610.

Abstract

During physiological gait, humans continuously modulate their knee stiffness, depending on the demands of the activity and the terrain. A similar functionality could be provided by modern actuators in transfemoral prosthesis. However, quantitative data on how knee stiffness is modulated during physiological gait is still missing. This is likely due to the experimental difficulties associated with identifying knee stiffness by applying perturbations during gait. It is our goal to quantify such stiffness modulation during gait without the need to apply perturbations. Therefore, we have recently presented an approach to quantify knee stiffness from kinematic, kinetic and electromyographic (EMG) measurements, and have validated it in isometric conditions. The goal of this paper is to extend this approach to non-isometric conditions by combining inverse dynamics and EMG measurements, and to quantify physiological stiffness modulation in the example of level-ground walking. We show that stiffness varies substantially throughout a gait cycle, with a stiffness of around 100 Nm/rad during swing phase, and a peak of 450 Nm/rad in stance phase. These quantitative results may be beneficial for design and control of transfemoral prostheses and orthoses that aim to restore physiological function.

Abstract

During physiological gait, humans continuously modulate their knee stiffness, depending on the demands of the activity and the terrain. A similar functionality could be provided by modern actuators in transfemoral prosthesis. However, quantitative data on how knee stiffness is modulated during physiological gait is still missing. This is likely due to the experimental difficulties associated with identifying knee stiffness by applying perturbations during gait. It is our goal to quantify such stiffness modulation during gait without the need to apply perturbations. Therefore, we have recently presented an approach to quantify knee stiffness from kinematic, kinetic and electromyographic (EMG) measurements, and have validated it in isometric conditions. The goal of this paper is to extend this approach to non-isometric conditions by combining inverse dynamics and EMG measurements, and to quantify physiological stiffness modulation in the example of level-ground walking. We show that stiffness varies substantially throughout a gait cycle, with a stiffness of around 100 Nm/rad during swing phase, and a peak of 450 Nm/rad in stance phase. These quantitative results may be beneficial for design and control of transfemoral prostheses and orthoses that aim to restore physiological function.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Balgrist University Hospital, Swiss Spinal Cord Injury Center
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:August 2014
Deposited On:21 Feb 2015 22:04
Last Modified:05 Apr 2016 18:59
Publisher:Institute of Electrical and Electronics Engineers
ISSN:1557-170X
Publisher DOI:https://doi.org/10.1109/EMBC.2014.6943912
PubMed ID:25570280

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