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

Overview

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.

Interventions

• 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.
• 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.

Primary outcome measures

• Strength of the foot lifters [Time frame: At the baseline, and after 1 month of rehabilitation course]

Secondary outcome measures (8)

• rPT values [Time frame: At the baseline, after 1 month of rehabilitation course , after 3 month follow-up and after 6 month follow-up]
• Peak torque resistance [Time frame: 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 [Time frame: At the baseline, after 1 month of rehabilitation course , after 3 month follow-up and after 6 month follow-up]
• The spasticity score measured [Time frame: 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. [Time frame: 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 [Time frame: 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, [Time frame: After 3 month follow-up and after 6 month follow-up]
• Collect the number of adverse events [Time frame: At the baseline, before the rehabilitation protocol, after 1 month of rehabilitation course, after 3 month follow-up and after 6 month follow-up]

Eligibility criteria

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

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Treatment

Study locations

Center list to be confirmed — check the primary protocol.

Identifiers

NCT: NCT07260565 · 2025-A00591-48 · 2025-A00591-48

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗