Muscle-tendon Interaction in the Spastic Sural Triceps During Gait

This project aims to study the mechanical behavior of the muscle-tendon unit (MTU) of the gastrocnemius medialis (GM) and the Achilles tendon (AT) in post-stroke and spinal cord injured (SCI) patients compared to a healthy population, focusing on the variations in muscle and tendon length during the stance phase of the gait cycle. The primary objective is to assess the respective contributions of the GM and AT lengthening in the MTU during walking. Inclusion criteria include adult post-stroke and post-SCI patients with voluntary motor function and some walking capacity. Methods include ultrasound measurements and 3D gait analysis.

Primary Objective: Evaluate the respective contributions of the gastrocnemius medialis (GM) muscle and the Achilles tendon (AT) within the muscle-tendon unit (MTU) during the single support phase of walking in post-stroke patients compared to healthy subjects.

Study Description: Strokes often lead to spastic paresis, degrading patients' walking performance. Instrumented gait analysis allows for the evaluation of these performances to propose adapted therapeutic strategies. This project will compare muscle and tendon behavior during walking between healthy individuals and post-stroke patients.

Methodology:

* Participants: Adult post-stroke patients or incomplete SCI patients with voluntary motor function on the triceps surae and walking capacity. Control group composed of healthy adults.
* Procedures:

  * Measure the force/length profile of the GM on an isokinetic dynamometer with simultaneous ultrasound.
  * Conduct gait analysis coupled with ultrasound to measure the lengths of the AT and GM.
  * Compare muscle and tendon length data during the stance phase of the gait cycle between the two groups.

Eligibility Criteria:
Inclusion Criteria :

Post-Stroke Population:

* Adult male or female
* Patient who had a stroke more than 7 days ago
* Patient hospitalized (in conventional hospitalization or day hospital) in the university neurological rehabilitation department of CHU de Nantes
* Patient with voluntary motor function graded between 2 and 4 on the MRC (Medical Research Council) scale at the GM level
* Patient classified between 3 and 8 on the New Functional Ambulation Classification

Post-Spinal Cord Injury Population:

* Adult male or female
* Patient with an incomplete spinal cord injury classified as ASIA AIS C or D from level C2 to L5
* Patient hospitalized (in conventional hospitalization or day hospital) in the neurological rehabilitation department of CHU de Nantes
* Patient with voluntary motor function graded between 2 and 4 on the MRC (Medical Research Council) scale at the GM level
* Patient classified between 3 and 8 on the New Functional Ambulation Classification

Healthy Population:

• Adult male or female without any neurological disorders

Exclusion Criteria :

Post-Stroke and Post-Spinal Cord Injury Population:

* Minor patient
* History of calf surgery, surgery to reduce triceps surae spasticity, or intramuscular injection (e.g., botulinum toxin) in the plantar flexors within the last 6 months
* Patient with a progressive condition contraindicating physical exertion (e.g., syrinx, cardiovascular instability)
* Peripheral pathology of the considered lower limb

Healthy Population:

* History of calf surgery
* History of muscle injury, fracture, or sprain of the lower limb within the last 3 months
* History of neurological disorders