A lower-limb powered exoskeleton for stroke patients: a feasibility study

Rationale: Stroke is one of the leading causes of disability of adults in the European Union. Around 80% of stroke survivors experience deficits in motor control, which results in gait and balance problems. The extent and amount of deficits differ per individual Frequently occurring motor impairments are spasticity of the plantar flexor muscles, muscle weakness of dorsiflexors and/or knee instability. An ankle foot orthoses (AFO) is frequently used to ensure stable and safe walking. However, a passive AFO does not support push-off, which is frequently injured in post-stroke patients. In the current study a powered lower extremity exoskeleton (ABLE-S) will be assessed. It should provide assistance during the push-off to increase forward propulsion and foot clearance and improve knee stability.
Objective: Determine if the ABLE-S exoskeleton can provide subject-specific assistance (in terms of type, level and timing of the assistance) to increase forward propulsion, foot clearance and/or knee stability, in hemiplegic stroke patients.
Study design: The current study is a cross-sectional observational study.
Study population: Five participants with unilateral hemiplegic chronic (> 6 months) stroke will be included in the current study. All participant should have a FAC ≥3 and an age above 18 years.
Main study parameters/endpoints: The main outcome parameters are joint angle of ankle and knee, to assess the ankle and knee movement. In other words, the dorsiflexion and plantarflexion of the ankle and the flexion and extension of the knee.
Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The current study consists of two visits to the lab of Roessingh Research and Development. During these visits several tests will be performed with ABLE-S and Vicon markers. There is no direct advantage for the participants and there are no negative effects of the planned measurements because the study load is low and there is enough room for rest between the different trials. The ABLE-S exoskeleton is not CE-certified and the main risk is a fall risk, this will be handled carefully by close supervision and familiarization with ZeroG.

It is expected that the ABLE-S exoskeleton can provide patient-specific assistance.

There are two time points. During the first time point gait analysis without the exoskeleton is performed. At this first session, sEMG data, position data, IMU data and ground reaction force will be gatherd, withoud wearing the exoskeleton. Based on the data of this first session the type of assistance (knee, ankle or both) in the second measurement session will be determined. At the second visit, sEMG data, position data, IMU data and ground reaction force will be gatherd while wearing the exoskeleton powered and unpowered.

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