Effectiveness of Robot-Assisted Structured Foot-Ankle Sensorimotor Training in Stroke Patients

Effectiveness of Robot-Assisted Structured Foot-Ankle Sensorimotor Training in Stroke Patients

Introduction: Stroke is a leading cause of long-term disability worldwide. Persistent lower-extremity motor and somatosensory impairments after stroke commonly limit walking and balance despite rehabilitation. Virtual reality (VR)-integrated robotic rehabilitation may support structured, goal-directed ankle-foot practice; however, there is limited evidence for ankle-foot-focused sensorimotor protocols. In particular, approaches that combine robot-assisted motor training with a plantar tactile localization task and VR-supported joint position sense (JPS) training to target plantar sensory and proprioceptive function are scarce. Therefore, this study aims to evaluate the effectiveness of a structured, VR-integrated, robot-assisted ankle-foot sensorimotor rehabilitation protocol in individuals with chronic stroke and to examine its effects on clinical and sensorimotor outcomes.

Methods and analysis: This is an assessor-blinded, two-arm, parallel-group randomized controlled trial. Thirty individuals with chronic stroke will be randomized 1:1 to the Robot-assisted Training Group (RTG) or the Manual Training Group (MTG). All participants will receive conventional rehabilitation; in addition, RTG will receive a structured robot-assisted ankle-foot training program integrated with virtual reality and assist-as-needed control, whereas MTG will receive the same structured ankle-foot training protocol delivered manually by a physiotherapist. Interventions will be delivered three times per week for 6 weeks (18 sessions), and total session duration will be time-matched between groups (50-60 min per session). The primary outcome will be the change in walking speed, derived from the 10-Meter Walk Test, from baseline to 6 weeks. Secondary outcomes will include 2-Minute Walk Test distance, ankle range of motion, joint position sense, plantar tactile sensation, muscle tone, motor performance, static and dynamic balance, and stroke-specific quality of life.

The inclusion criteria are as follows:

1. Age 40-65 years,
2. Able to understand and follow study instructions,
3. Able to communicate coherently and oriented in time and place,
4. Provided written informed consent,
5. Stroke ≥6 months prior to enrollment (chronic stroke),
6. Ankle plantarflexor spasticity ≤2 on the Modified Ashworth Scale,
7. Ankle dorsiflexor strength ≥ grade 2 on the Medical Research Council (MRC) scale,
8. Passive ankle dorsiflexion to neutral (90°; 0°) without a plantarflexion contracture,
9. Moderate or mild lower-extremity impairment based on the Fugl-Meyer Assessment-Lower Extremity (FMA-LE) score (21-27 moderate; 28-34 mild/good),
10. Able to sit for at least 1 hour,
11. Able to walk at least 10 meters with or without an assistive device,
12. Completed all conventional lower-extremity physical therapy and rehabilitation programs.

The exclusion criteria are as follows:

1. Cognitive impairment (Mini-Mental State Test score ≤ 24),
2. Conditions affecting walking or balance (e.g., orthopedic complications, lower extremity amputation, osteoporosis),
3. Insufficient visual acuity to view a screen (e.g., diplopia),
4. Severe visual deficits (e.g., hemianopia) or vestibular disorders34,
5. Sensory deficits such as hemisensory neglect,
6. Acute musculoskeletal or cardiovascular disorders,
7. Intrathecal baclofen pump use or botulinum toxin injections within the past 5 months,
8. Fixed or painful contracture of the paretic ankle,
9. Uncontrolled systemic diseases (e.g., diabetes, hypertension, debilitating or immunosuppressive diseases),
10. history of a non-stroke neurological disease/disorder that may impair comprehension of instructions,
11. Concurrent participation in other lower-extremity physical therapy, robotic rehabilitation, or neurological exercise programs.