Ankle-Foot-Orthosis “Hermes” Compensates Pathological Ankle Stiffness of Chronic Stroke—A Proof of Concept

Journal Article (2023)
Author(s)

K.E. Rodriguez Hernandez (TU Delft - Biomechatronics & Human-Machine Control)

J.H. de Groot (Leiden University Medical Center)

Frank Baas (InteSpring BV)

M. Stijntjes (TU Delft - Support Biomechanical Engineering, Leiden University Medical Center)

E.R.M. Grootendorst (Leiden University Medical Center, TU Delft - Biomechatronics & Human-Machine Control)

S.K. Schiemanck (Leiden University Medical Center, TU Delft - Biomechanical Engineering)

F.C.T. van Der Helm (TU Delft - Biomechatronics & Human-Machine Control)

H. van der Kooij (TU Delft - Support Biomechanical Engineering, University of Twente)

Winfred Mugge (TU Delft - Biomechatronics & Human-Machine Control)

Research Group
Biomechatronics & Human-Machine Control
Copyright
© 2023 K.E. Rodriguez Hernandez, J.H. de Groot, Frank Baas, M. Stijntjes, E.R.M. Grootendorst, S.K. Schiemanck, F.C.T. van der Helm, H. van der Kooij, W. Mugge
DOI related publication
https://doi.org/10.1109/TNSRE.2023.3310337
More Info
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Publication Year
2023
Language
English
Copyright
© 2023 K.E. Rodriguez Hernandez, J.H. de Groot, Frank Baas, M. Stijntjes, E.R.M. Grootendorst, S.K. Schiemanck, F.C.T. van der Helm, H. van der Kooij, W. Mugge
Research Group
Biomechatronics & Human-Machine Control
Volume number
31
Pages (from-to)
3535-3544
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Abstract

Individuals with an upper motor neuron syndrome, e.g., stroke survivors, may have a pathological increase of passive ankle stiffness due to spasticity, that impairs ankle function and activities such as walking. To improve mobility, walking aids such as ankle-foot orthoses and orthopaedic shoes are prescribed. However, these walking aids generally limit the range of motion (ROM) of the foot and may therewith negatively influence activities that require a larger ROM. Here we present a new ankle-foot orthosis 'Hermes', and its first experimental results from four hemiparetic chronic stroke patients. Hermes was designed to facilitate active ankle dorsiflexion by mechanically compensating the passive ankle stiffness using a negative-stiffness mechanism. Four levels of the Hermes' stiffness compensation (0%, 35%, 70% and 100%) were applied to evaluate active ROM in a robotic ankle manipulator and to test walking feasibility on an instrumented treadmill, in a single session. The robotic tests showed that Hermes successfully compensated the ankle joint stiffness in all four patients and improved the active dorsiflexion ROM in three patients. Three patients were able to walk with Hermes at one or more Hermes' stiffness compensation levels and without reducing their preferred walking speeds compared to those with their own walking aids. Despite a small sample size, the results show that Hermes holds great promise to support voluntary ankle function and to benefit walking and daily activities.