Impact of a Sequential Isokinetic Fatigue Protocol Followed by Ankle Strengthening After Botulinum Toxin Injection Into Spastic Plantar Flexors on Foot Lift Strength and Walking (ISOTOX)

Spastic foot drop (speed- and force-dependent hypertonia) is one of the most common neuro-orthopaedic disorders following brain injury. It has a negative impact on walking and is closely linked to independence in activities of daily living.

This disorder combines a deficit in muscle strength in the plantar flexors and extensors with pathological hypertonia of the plantar flexors, causing an imbalance in ankle flexion and resulting in equinus deformity of the foot.

Botulinum toxin is the first-line pharmacological treatment for focal spasticity of neurological origin, and its effectiveness is directly linked to the quality and quantity of associated rehabilitation care. However, the associated rehabilitation protocols remain vague and are based on general recommendations combining: stretching of muscles and tendons, muscle strengthening of spastic muscles, their agonists and antagonists, and functional work. The standard rehabilitation protocol used in our centre will be detailed in the study protocol.

The isokinetic dynamometer is an open-chain muscle strengthening tool that has the advantage of introducing a concept of reproducible assessment and rehabilitation.

This reproducibility is difficult to guarantee with the rehabilitation techniques practised by a therapist, whose applied force and precision may vary from one session to another. We have therefore developed a sequential muscle strengthening protocol combining strengthening work - fatigue of the triceps surae followed by muscle strengthening work of the foot lifters.

The aim of this work is to determine the effects of this protocol compared to conventional rehabilitation aimed at promoting the post-injection effects of botulinum toxin.

Study Overview

• Status: Not yet recruiting
• Conditions: Spasticity of the Plantar Flexors
• Intervention / Treatment: Procedure: standard rehabilitation programme; Procedure: Isokinetic rehabilitation protocol.

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Aurélie DUSSAUSSOY, Clinical research associated; Phone Number: 03 22 33 74 78; Email: aurelie.dussaussoy@pauchet.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adult patient
• Patient with spastic hemiplegia (regardless of cause)
• MAS 1-2 spasticity of the plantar flexors
• Deficit of the foot lifters at the minimum stage of contraction with movement
• Patient who has received botulinum toxin injections in the plantar flexors
• Patient who has been informed about the research and has given their written and signed informed consent
• Patient affiliated with a social security scheme or beneficiary of such a scheme

Exclusion Criteria:

• Refusal of consent
• Patient with severe cognitive impairment (MMSE <23/30)
• Surgery on the affected lower limb
• Patient unable to read, write or understand French
• Patient who is pregnant or breastfeeding, in accordance with Article L1121-5 of the CSP
• Vulnerable patients according to Article L1121-6 of the CSP
• Adult patients under guardianship, curatorship or judicial protection
• Patients unable to give their consent in person according to Article L.1121-8 of the CSP or adults protected by law

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: standard rehabilitation protocol; Patients in this groupe will undergo a standard rehabilitation programme five times a week, Monday to Friday, combining physiotherapy and adapted physical activity.	Procedure: standard rehabilitation programme; Patients in group will undergo a standard rehabilitation programme five times a week, Monday to Friday, combining physiotherapy and adapted physical activity.
Experimental: isokinetic rehabilitation protocol; Patients in this group will undergo isokinetic rehabilitation five times a week, Monday to Friday, and will receive treatment combining physiotherapy, adapted physical activity (see standard rehabilitation protocol) and strengthening on an isokinetic dynamometer.	Procedure: Isokinetic rehabilitation protocol.; Patients in group will undergo isokinetic rehabilitation therapy five times a week, Monday to Friday, combining physiotherapy, adapted physical activity (see standard rehabilitation protocol) and strengthening exercises on an isokinetic dynamometer.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Strength of the foot lifters	The strength of the foot lifters will be assessed by the maximum peak torque of the foot lifters at 60° (rPT 60°) measured using an isokinetic dynamometer. The primary endpoint is the change in rPT 60° between the value at inclusion and the value at the end of rehabilitation. This endpoint will be compared between the two arms.	At the baseline, and after 1 month of rehabilitation course

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
rPT values	rPT values	At the baseline, after 1 month of rehabilitation course , after 3 month follow-up and after 6 month follow-up
Peak torque resistance	Measured using an isokinetic dynamometer at different angular velocities.	At the baseline, after 1 month of rehabilitation course, after 3 month follow-up and after 6 month follow-up
Measurement of the agonist/antagonist ratio	using the isokinetic dynamometer at different visits.	At the baseline, after 1 month of rehabilitation course , after 3 month follow-up and after 6 month follow-up
The spasticity score measured	using the Modified Aschworth Scale and stretch reflex measurement at different visits.	Before the rehabilitation protocol, during the consultation for the botulinum toxin injection , after 1 month of rehabilitation course , after 3 month follow-up and after 6 month follow-up
The distance covered during a 6-minute walk test and the walking speed measured during a 10-metre walk test at the various follow-up visits.	The distance covered during a 6-minute walk test and the walking speed measured during a 10-metre walk test at the various follow-up visits.	Before the rehabilitation protocol, during the consultation for the botulinum toxin injection, after 1 month of rehabilitation course, after 3 month follow-up and after 6 month follow-up
The exercise tolerance score	Using the Borg scale	Before the rehabilitation protocol, during the consultation for the botulinum toxin injection, after 1 month of rehabilitation course , after 3 month follow-up and after 6 month follow-up
Clinical improvement in spasticity,	which will be assessed by the doctor in charge of the patient	After 3 month follow-up and after 6 month follow-up
Collect the number of adverse events	Collect the number of adverse events	At the baseline, before the rehabilitation protocol, after 1 month of rehabilitation course, after 3 month follow-up and after 6 month follow-up

Collaborators and Investigators

• Sponsor: Clinique Victor Pauchet

Study record dates

Study Major Dates

• Study Start (Estimated): January 1, 2026
• Primary Completion (Estimated): November 1, 2028
• Study Completion (Estimated): November 1, 2028

Study Registration Dates

• First Submitted: September 25, 2025
• First Submitted That Met QC Criteria: November 28, 2025
• First Posted (Estimated): December 3, 2025

Study Record Updates

• Last Update Posted (Actual): December 17, 2025
• Last Update Submitted That Met QC Criteria: December 16, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Other Study ID Numbers: 2025-A00591-48 (Other Identifier: ID-RCB)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No