Compensating the Symptomatic Increase in Plantarflexion Torque and Mechanical Work for Dorsiflexion in Patients with Spastic Paresis Using the “Hermes” Ankle–Foot Orthosis

K.E. Rodriguez Hernandez; J.H. de Groot; Eveline R. M.  Grootendorst-Heemskerk; Frank Baas; M. Stijntjes; S.K. Schiemanck; F.C.T. van der Helm; H. van der Kooij; W. Mugge

doi:10.3390/prosthesis7010012

Compensating the Symptomatic Increase in Plantarflexion Torque and Mechanical Work for Dorsiflexion in Patients with Spastic Paresis Using the “Hermes” Ankle–Foot Orthosis

K.E. Rodriguez Hernandez^*, J.H. de Groot, Eveline R. M. Grootendorst-Heemskerk, Frank Baas, M. Stijntjes, S.K. Schiemanck, F.C.T. van der Helm, H. van der Kooij, W. Mugge

^*Corresponding author for this work

Biomechatronics & Human-Machine Control

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Abstract

Background/Objectives: “Hermes” is an ankle–foot orthosis (AFO) with negative stiffness designed to mechanically compensate the symptomatic increase in plantarflexion (PF) torque (i.e., ankle joint torque resistance to dorsiflexion, DF) in patients with spastic paresis. Methods: The effectiveness of “Hermes” was evaluated in twelve patients with chronic unilateral spastic paresis after stroke. Using a robotic ankle manipulator, stiffness at the ankle joint was assessed across three conditions: ankle without Hermes (𝐴A), ankle with Hermes applying no torque compensation (𝐴+𝐻0%A+H0%), and ankle with Hermes tuned to compensate 100% of the patients’ ankle joint stiffness (𝐴+𝐻100%A+H100%). Results: A significant reduction in PF torque was found with Hermes applying compensation (𝐴+𝐻100%A+H100%) compared to the conditions without Hermes (𝐴A) and with Hermes applying no compensation (𝐴+𝐻0%A+H0%). Furthermore, a significant reduction in positive dorsiflexion work was found with Hermes applying compensation (𝐴+𝐻100%A+H100%) compared to the condition with Hermes applying no compensation (𝐴+𝐻0%A+H0%). Hermes did not significantly contribute to additional PF torque or positive work when applying no compensation (𝐴+𝐻0%A+H0%). Conclusions: The reductions in PF torque achieved with Hermes are comparable to those seen with repeated ankle stretching programs and ankle robot training. Thus, Hermes is expected to assist voluntary dorsiflexion and improve walking in patients with spastic paresis.

Original language	English
Article number	12
Number of pages	16
Journal	Prosthesis
Volume	7
Issue number	1
DOIs	https://doi.org/10.3390/prosthesis7010012
Publication status	Published - 2025

Keywords

muscle spasticity
stroke
equinus deformity
ankle work

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10.3390/prosthesis7010012

prosthesis-07-00012Final published version, 4.39 MBLicence: CC BY

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Rodriguez Hernandez, K. E., de Groot, J. H., Grootendorst-Heemskerk, E. R. M., Baas, F., Stijntjes, M., Schiemanck, S. K., van der Helm, F. C. T., van der Kooij, H., & Mugge, W. (2025). Compensating the Symptomatic Increase in Plantarflexion Torque and Mechanical Work for Dorsiflexion in Patients with Spastic Paresis Using the “Hermes” Ankle–Foot Orthosis. Prosthesis, 7(1), Article 12. https://doi.org/10.3390/prosthesis7010012

@article{5ff793f5853046c98b5d4cd1f3660e24,

title = "Compensating the Symptomatic Increase in Plantarflexion Torque and Mechanical Work for Dorsiflexion in Patients with Spastic Paresis Using the “Hermes” Ankle–Foot Orthosis",

abstract = "Background/Objectives: “Hermes” is an ankle–foot orthosis (AFO) with negative stiffness designed to mechanically compensate the symptomatic increase in plantarflexion (PF) torque (i.e., ankle joint torque resistance to dorsiflexion, DF) in patients with spastic paresis. Methods: The effectiveness of “Hermes” was evaluated in twelve patients with chronic unilateral spastic paresis after stroke. Using a robotic ankle manipulator, stiffness at the ankle joint was assessed across three conditions: ankle without Hermes (𝐴A), ankle with Hermes applying no torque compensation (𝐴+𝐻0\%A+H0\%), and ankle with Hermes tuned to compensate 100\% of the patients{\textquoteright} ankle joint stiffness (𝐴+𝐻100\%A+H100\%). Results: A significant reduction in PF torque was found with Hermes applying compensation (𝐴+𝐻100\%A+H100\%) compared to the conditions without Hermes (𝐴A) and with Hermes applying no compensation (𝐴+𝐻0\%A+H0\%). Furthermore, a significant reduction in positive dorsiflexion work was found with Hermes applying compensation (𝐴+𝐻100\%A+H100\%) compared to the condition with Hermes applying no compensation (𝐴+𝐻0\%A+H0\%). Hermes did not significantly contribute to additional PF torque or positive work when applying no compensation (𝐴+𝐻0\%A+H0\%). Conclusions: The reductions in PF torque achieved with Hermes are comparable to those seen with repeated ankle stretching programs and ankle robot training. Thus, Hermes is expected to assist voluntary dorsiflexion and improve walking in patients with spastic paresis.",

keywords = "muscle spasticity, stroke, equinus deformity, ankle work",

author = "\{Rodriguez Hernandez\}, K.E. and \{de Groot\}, J.H. and Grootendorst-Heemskerk, \{Eveline R. M.\} and Frank Baas and M. Stijntjes and S.K. Schiemanck and \{van der Helm\}, F.C.T. and \{van der Kooij\}, H. and W. Mugge",

year = "2025",

doi = "10.3390/prosthesis7010012",

language = "English",

volume = "7",

journal = "Prosthesis",

issn = "2673-1592",

publisher = "MDPI",

number = "1",

}

Rodriguez Hernandez, KE , de Groot, JH, Grootendorst-Heemskerk, ERM, Baas, F, Stijntjes, M, Schiemanck, SK , van der Helm, FCT , van der Kooij, H & Mugge, W 2025, 'Compensating the Symptomatic Increase in Plantarflexion Torque and Mechanical Work for Dorsiflexion in Patients with Spastic Paresis Using the “Hermes” Ankle–Foot Orthosis', Prosthesis, vol. 7, no. 1, 12. https://doi.org/10.3390/prosthesis7010012

Compensating the Symptomatic Increase in Plantarflexion Torque and Mechanical Work for Dorsiflexion in Patients with Spastic Paresis Using the “Hermes” Ankle–Foot Orthosis. / Rodriguez Hernandez, K.E.; de Groot, J.H.; Grootendorst-Heemskerk, Eveline R. M. et al.
In: Prosthesis, Vol. 7, No. 1, 12, 2025.

Research output: Contribution to journal › Article › Scientific › peer-review

TY - JOUR

T1 - Compensating the Symptomatic Increase in Plantarflexion Torque and Mechanical Work for Dorsiflexion in Patients with Spastic Paresis Using the “Hermes” Ankle–Foot Orthosis

AU - Rodriguez Hernandez, K.E.

AU - de Groot, J.H.

AU - Grootendorst-Heemskerk, Eveline R. M.

AU - Baas, Frank

AU - Stijntjes, M.

AU - Schiemanck, S.K.

AU - van der Helm, F.C.T.

AU - van der Kooij, H.

AU - Mugge, W.

PY - 2025

Y1 - 2025

N2 - Background/Objectives: “Hermes” is an ankle–foot orthosis (AFO) with negative stiffness designed to mechanically compensate the symptomatic increase in plantarflexion (PF) torque (i.e., ankle joint torque resistance to dorsiflexion, DF) in patients with spastic paresis. Methods: The effectiveness of “Hermes” was evaluated in twelve patients with chronic unilateral spastic paresis after stroke. Using a robotic ankle manipulator, stiffness at the ankle joint was assessed across three conditions: ankle without Hermes (𝐴A), ankle with Hermes applying no torque compensation (𝐴+𝐻0%A+H0%), and ankle with Hermes tuned to compensate 100% of the patients’ ankle joint stiffness (𝐴+𝐻100%A+H100%). Results: A significant reduction in PF torque was found with Hermes applying compensation (𝐴+𝐻100%A+H100%) compared to the conditions without Hermes (𝐴A) and with Hermes applying no compensation (𝐴+𝐻0%A+H0%). Furthermore, a significant reduction in positive dorsiflexion work was found with Hermes applying compensation (𝐴+𝐻100%A+H100%) compared to the condition with Hermes applying no compensation (𝐴+𝐻0%A+H0%). Hermes did not significantly contribute to additional PF torque or positive work when applying no compensation (𝐴+𝐻0%A+H0%). Conclusions: The reductions in PF torque achieved with Hermes are comparable to those seen with repeated ankle stretching programs and ankle robot training. Thus, Hermes is expected to assist voluntary dorsiflexion and improve walking in patients with spastic paresis.

AB - Background/Objectives: “Hermes” is an ankle–foot orthosis (AFO) with negative stiffness designed to mechanically compensate the symptomatic increase in plantarflexion (PF) torque (i.e., ankle joint torque resistance to dorsiflexion, DF) in patients with spastic paresis. Methods: The effectiveness of “Hermes” was evaluated in twelve patients with chronic unilateral spastic paresis after stroke. Using a robotic ankle manipulator, stiffness at the ankle joint was assessed across three conditions: ankle without Hermes (𝐴A), ankle with Hermes applying no torque compensation (𝐴+𝐻0%A+H0%), and ankle with Hermes tuned to compensate 100% of the patients’ ankle joint stiffness (𝐴+𝐻100%A+H100%). Results: A significant reduction in PF torque was found with Hermes applying compensation (𝐴+𝐻100%A+H100%) compared to the conditions without Hermes (𝐴A) and with Hermes applying no compensation (𝐴+𝐻0%A+H0%). Furthermore, a significant reduction in positive dorsiflexion work was found with Hermes applying compensation (𝐴+𝐻100%A+H100%) compared to the condition with Hermes applying no compensation (𝐴+𝐻0%A+H0%). Hermes did not significantly contribute to additional PF torque or positive work when applying no compensation (𝐴+𝐻0%A+H0%). Conclusions: The reductions in PF torque achieved with Hermes are comparable to those seen with repeated ankle stretching programs and ankle robot training. Thus, Hermes is expected to assist voluntary dorsiflexion and improve walking in patients with spastic paresis.

KW - muscle spasticity

KW - stroke

KW - equinus deformity

KW - ankle work

UR - https://www.scopus.com/pages/publications/85218887804

U2 - 10.3390/prosthesis7010012

DO - 10.3390/prosthesis7010012

M3 - Article

SN - 2673-1592

VL - 7

JO - Prosthesis

JF - Prosthesis

IS - 1

M1 - 12

ER -

Compensating the Symptomatic Increase in Plantarflexion Torque and Mechanical Work for Dorsiflexion in Patients with Spastic Paresis Using the “Hermes” Ankle–Foot Orthosis

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Compensating the Symptomatic Increase in Plantarflexion Torque and Mechanical Work for Dorsiflexion in Patients with Spastic Paresis Using the “Hermes” Ankle–Foot Orthosis

Abstract

Keywords

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Data set of "Compensating the Symptomatic Increase of in Plantarflexion Torque and Mechanical Work for Dorsiflexion in Patients with Spastic Paresis Using the “Hermes” Ankle-Foot-Orthosis"

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