The main hypothesis of the present study is that a safer knee joint is likely to encourage post stroke patients at an early stage to rely on their hemiparetic leg and transfer their weight onto it while walking. The main purpose of the present work is to assess the feasibility of FES-induced muscular control of the hemiplegic knee joint in order to improve stance phase support symmetry recovery in individuals with post stroke hemiplegia. Functional electrical stimulation (FES) is delivered to the quadriceps and hamstrings of the paretic limb based on the real-time estimation of the knee angle and support phase.

The process of gait recovery in patients with severe post-stroke hemiplegia requires a significant investment and effort for both the patient and the therapist and is not always leading to a safe and autonomous gait. Increasing the chances for the patients of regaining a functional walking gait within limited timeframes is a challenge. Several studies have focused their attention on the neurological foot in the chronic phase because a poorly controlled foot dorsiflexion is a factor limiting gait recovery and increasing fall risk. Functional Electrical Stimulation (FES) can be used as an alternative to an orthosis to restore walking by activating paralyzed muscles. FES has been extensively studied to correct drop foot by activating foot dorsiflexors or inducing a withdrawal reflex.

Few studies have considered knee joint which has a major role, especially for the quality of the support, and this over the entire cycle of walking. In the initial phase after stroke, ensuring a safe knee control remains difficult because of the associated disorders including the lack of proprioceptive feedback. Classical observed disorders in this population are knee hyperextension during the stance phase (genu recurvatum) and flexed knees (crouch gait). Fixed orthoses are usually used to prevent this by limiting knee flexion or extension over the gait. FES is also an alternative to produce appropriately timed knee flexion or extension. Bioness L300 Plus© device proposes a thigh cuff embedding electrodes stimulating the quadriceps muscles to extend knee at the appropriate time during gait based on shank angle observation. Previous studies have investigated the contribution of quadriceps and gluteus maximus stimulation in improving standing balance and weight transfer or hamstrings stimulation associated to foot dorsiflexors stimulation in improving gait performance.

One of the main objectives of an early rehabilitation is to encourage patients with hemiplegia to rely on their paretic leg and to transfer their weight onto it while walking. Depending on the gait phase, the knee extension and flexion are restricted to a safety range by the adaptive delivery of quadriceps and hamstring electrical stimulation. A sensor network detects gait phases and knee angle evolution from which stimulation levels are modulated.

Inclusion Criteria:

• Age > or = 18 years
• Cerebral injury or stroke
• Interval time since the onset of the neurological event: min 8 weeks (in case of an acute cerebral damage) or at a any time in case of a chronic affection
• Surface electrical stimulation of quadriceps and hamstrings possible
• Free range of motion in lower limbs
• Ankle-foot orthosis, dynamic or static
• Limited perimeter distance < 50 meters with or without walking technical aids

Exclusion Criteria:

• Knee-Ankle-Foot orthosis is required
• Body mass index > or = 30
• Thrombophlebitis
• Muscular pathology
• Unstable Cardio-Vascular pathology
• Lower limb prosthesis
• Unstable seizures
• Orthostatic hypotension
• Recent fracture in lower limbs (<12 months)
• Pacemaker
• Pregnancy
• Betablockers

FES-based control of knee joint to reduce stance phase asymmetry during gait in patients with post-stroke hemiplegia