Publication type: Conference other
Type of review: Peer review (abstract)
Title: Ankle kinematics during walking with a soft exoskeleton in people with dropfoot – a case series
Authors: Graf, Eveline
Wirz, Markus
Pauli, Carole
Bauer, Christoph
et. al: No
Conference details: XXVIII Congress of the International Society of Biomechanics, online, 25-29 July 2021
Issue Date: Jul-2021
Language: English
Subject (DDC): 610: Medicine and health
Abstract: Summary: The effect of XoSoft, a soft exoskeleton providing support during dorsiflexion at the ankle, was analyzed in people with drop foot. This study identifies areas of future research in order to achieve the goal of a support system at the ankle that results in high adherence. Introduction: Dropfoot, caused by neurological conditions, is characterized by weakness of the dorsiflexor muscles at the ankle. It results in altered walking mechanics and increased risk of falling due to reduced foot-ground clearance. While there are orthotic solutions available, limited comfort and wearability as well as their limited mobility result in a low adherence of patients. Consequently, a novel comfortable and dynamic solution has great potential, but its functionality must be demonstrated. The aim of this study was to assess the influence of a prototype soft exoskeleton on ankle kinematics in individuals with dropfoot during walking. Methods: Three participants with dropfoot (2 female, 2 incomplete spinal cord injury/1 stroke, 2 with unilateral impairment) walked without support (none) and with the XoSoft prototype. A minimum of four trials were recorded and averaged. Ankle kinematics was recorded with a camera system (240 Hz, Vicon Vantage, Vicon Motion Systems Ltd.) and a cluster marker approach. In agreement with the case study characteristics, data were analyzed descriptively. The XoSoft prototype consisted of a soft, pneumatic clutch in series with an elastic band. The two ends were anchored at the shoe and the shin. The clutch was active from 50 to 0 % of gait cycle. The elongation of the distance of the anchor points during push-off (clutch activated) was thought to result in elongation of the elastic band which released its energy during the swing phase, keeping the foot in a dorsiflexed position. Results and Discussion: For all three participants, XoSoft was able to increase dorsiflexion during the swing phase; the effect was, however, small with less than 10° difference between conditions. Participant 2 reaches a plateau with XoSoft between 60-80% of gait cycle. It is assumed that the participant may not be able to push-off actively and, therefore, cannot elongate the dorsiflexion clutch enough. When the foot is lifted off the ground, the elastic band can maintain the foot at this position but not actively pull it up. The inertia of the foot during the swing phase may cause the decrease in dorsiflexion in later swing. Consequently, the participant would benefit from a stiffer dorsiflexion elastic band in combination with active support of the plantarflexion during the push-off movement. All participants (except participant 1) had a plantarflexion movement at the beginning of the gait cycle that was enabled or increased with XoSoft. Having an initial plantarflexion movement represents a more physiological pattern with heelstrike, followed by flattening of the foot. Participant 1 had a reduced active and passive range of motion in dorsiflexion. It is concluded that the elastic band was not stiff enough to maintain the ankle in dorsiflexion while landing. Conclusions: Overall, these results indicate that XoSoft can alter gait pattern of the ankle and allow a more natural gait despite an inability of the participants to perform this movement actively. Additional research looking into actuation of the plantarflexion during push-off in combination with a fine tuning of the elastic band is necessary.
Fulltext version: Published version
License (according to publishing contract): Licence according to publishing contract
Departement: School of Health Sciences
Organisational Unit: Institute of Physiotherapy (IPT)
Appears in collections:Publikationen Gesundheit

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