Effects of Unilateral Robotic Assistance on Compensation Strategies and Muscular Activity During Hemiparetic Gait

Assessment of the Evolution of Compensatory Strategies and Muscular Response in Hemiparetic Post-stroke Gait Due to Unilateral Robotic Assistance

Hemiparetic gait is characterized by strong asymmetries that could severely affect the quality of life of stroke survivors. This asymmetry is due to motor deficits in the paretic leg and the resulting compensations in the non-paretic limb.

In this study, the investigators aim to evaluate the effect of actively promoting gait symmetry in hemiparetic patients by assessing the motion and muscular activity of both paretic and non-paretic lower limbs. To this end, the investigators use a unilateral active Knee-Ankle-Foot Orthosis able to assist the paretic limb of hemiparetic patients during gait.

The system is able to synchronize its action with the movement of the unassisted joints, promoting a natural and intuitive interaction. The device generates assistance to induce a healthy gait pattern on the paretic leg.

The hypothesis is that a proper and natural interaction between the user and the exoskeleton would enable the patients to consider the robot action as a part of their own gait capability, improving their gait quality as consequence. Hemiparetic asymmetry is not only due to impairments in the affected limb, but also it is the consequence of biomechanical compensatory mechanisms that might arose in the non-paretic leg. The aim of this study is to assess the adaptation process of the subject to the exoskeleton assistance, and to evaluate the effects of such human-robot interaction in both paretic and non-paretic legs.

Study Overview

• Status: Completed
• Conditions: Hemiparesis/Hemiplegia (One Sided Weakness/Paralysis)
• Intervention / Treatment: Device: Exoskeleton assisted gait on a treadmill

Detailed Description

- Materials: The investigators have developed a Knee-Ankle-Foot orthosis (KAFO) composed of two joints aligned to the knee and ankle of the user. The length of its bars and the positions of its braces can be tailored to the anthropometry of different users. The knee joint is actuated by a DC brushless motor EC-60 flat 408057 (Maxon ag, Switzerland) coupled with a harmonic drive CSD-20-160-2AGR (Harmonic Drive LLC, EE.UU.). The transmission ratio of 1:60 of this system enables the application of a mean torque of 35Nm. The ankle joint of the prototype remains non-actuated and unlimited, enabling its free movement in the sagittal plane. The total weight of the KAFO is about 4kg.

The prototype is equipped with sensors that provide information on system variables that are used for its control in real-time, such as the flexion angle of the robot joint or the interaction torque between user and robot. In addition, the gait kinematic of the user is measured by Inertial Measurement Units (IMUs) and the contact of both feet with the floor by Force Sensing Resistors (FSRs).

The system uses an Adaptive Frequency Oscillator to estimate the continuous gait phase of the contralateral limb and synchronically assists the paretic leg by inducing a healthy gait pattern. The action of the robot depends on the gait phase of the assisted leg: during the stance phase, the robot reinforces the limb so the system composed of the leg and the exoskeleton can load the user's weight and not collapse, while during the swing phase the robot guides the limb's movement according to the Assisted-As-Needed (AAN) paradigm creating a force tunnel around the prescribed trajectory.

- Procedures:

The experimental protocol is divided in three sessions. During all of them, the patient will walk on a treadmill commanded by the physiotherapist while wearing a safety harness to avoid falls and while wearing the robotic exoskeleton in the paretic leg. During the second and third sessions, electromyography will also be acquired by using surface electrodes (Trigno System, Delsys Inc.) and according to the SENIAM guidelines. The muscle activity of Rectus Femoris, Biceps Femoris Long Head, Tibialis Anterior and Medial Gastrocnemius of both legs will be measured through this method. Each experimental session is described next:

1. - Training session: The patient will wear the robotic exoskeleton to familiarize with the action of the device. Comfortable and maximum velocities will be identified for each subject.
2. - Ramp Velocity Session: the session will be divided into five trials: (a) Pre, the patient will not wear the device; (b) Free, the patient will wear the robot but it is mechanically decoupled so it will enable the free knee movement; (c) Active, the robot will assist the gait until 75% maximum gait velocity ; (d) MaxActive, the robot will assist the gait until maximum gait velocity ; and (e) Post, the patient will repeat the Pre condition. Velocity will increase from a comfortable velocity to the maximum and then come back to the comfortable one.
3. - Random Velocity session: the session will be divided into the same trials than the Ramp Velocity Session.

The difference between RampVel and RandomVel sessions will be the sequence of gait speeds at which the patient will walk. During RampVel, five velocity steps will be defined from comfortable to maximum velocity with or without exo (depending on the trial) and coming back to comfortable velocity. During RandomVel, the same range of velocity will be used, but defining five steps in the whole range and setting them in a random order. In both sessions, each gait speed step will last one minute, therefore, all trials will last five minutes. Trials Free, Active and MaxActive will be also randomly ordered in each session.

Between trials, patients will rest during 10 minutes to avoid summation effects. Each session will occur in different days, leaving 1 or 2 days in between.

- Intervention providers A physiotherapist and an engineer will be present during the trials. The first will be responsible of assessing the basal gait of the subjects and evaluating his/her state while the assistance is provided. The engineer will be responsible of managing the device and recording the data.

Both researchers monitor fidelity to the intervention by direct supervision.

• Modes of delivery The protocol is provided to one participant at a time. Each patient completes the protocol once.
• Location Hospital Beata María Ana (Madrid, Spain)
• Tailoring and modifications The protocol remains unaltered across applications. The only adaptation to patients is the choice of the comfortable and maximum gait speeds for the trials.

• Study Type: Interventional
• Enrollment (Actual): 10
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Spain
  • Madrid, Spain, 28041
    • Hospital Beata María Ana

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 85 years (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria Ischemic or haemorrhagic stroke that lead to hemiplegic gait

Exclusion Criteria:

1. Acute musculoskeletal diseases
2. Peripheral vascular diseases
3. Acute cardiopulmonary diseases
4. Acute neurological diseases
5. Excessive spasticity in any joint of the lower limb (Ashworth scale> 2)
6. Joint mobility restriction of lower limb joints due to any cause
7. Pain due to impaired mobility of the lower limb
8. Inability to use robotic exoskeleton prototypes due to his/her health condition.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: BASIC_SCIENCE
• Allocation: NA
• Interventional Model: SINGLE_GROUP
• Masking: NONE

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

EXPERIMENTAL: Hemiparetic patients; Patients with hemiparetic gait who will be assisted by the exoskeleton action

Device: Exoskeleton assisted gait on a treadmill; The experimental protocol is divided in three sessions. During all of them, the patient will walk on a treadmill for 6 minutes while wearing a safety harness and the robotic exoskeleton in the paretic leg.; - Training session: The patient will wear the robotic exoskeleton to familiarize with the action of the device.; - Ramp Velocity Session: the session will be divided into five trials: (a) Pre, the patient will not wear the device; (b) Free, the patient will wear the robot but it is mechanically decoupled so it will enable the free knee movement; (c) Active, the robot will assist the gait until 75% maximum gait velocity ; (d) MaxActive, the robot will assist the gait until maximum gait velocity ; and (e) Post, the patient will repeat the Pre condition. Velocity will increase from comfortable velocity to the maximum and then come back to the comfortable one.; - Random Velocity session: the session will be divided into the same trials than the Ramp Velocity Session.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Symmetry of knee flexion/extension kinematics	The joint motion will be measured by Inertial Sensors	During the intervention
Symmetry of Integrated EMG in Rectus Femoris	The muscle activity data will be acquired by EMG sensors according to the SENIAM guidelines	During the intervention
Symmetry of Integrated EMG in Biceps Femoris Long Head	The muscle activity data will be acquired by EMG sensors according to the SENIAM guidelines	During the intervention
Symmetry of Integrated EMG in Tibialis Anterior	The muscle activity data will be acquired by EMG sensors according to the SENIAM guidelines	During the intervention
Symmetry of Integrated EMG in Medial Gastrocnemius	The muscle activity data will be acquired by EMG sensors according to the SENIAM guidelines	During the intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Symmetry of step time	Floor contact events are detected by FSRs	During the intervention
Symmetry of step length	Thigh and shank kinematics measured by inertial sensors	During the intervention

Collaborators and Investigators

• Sponsor: Spanish National Research Council
• Collaborators: Hospital Beata María Ana

Study record dates

Study Major Dates

• Study Start (ACTUAL): October 18, 2021
• Primary Completion (ACTUAL): March 1, 2022
• Study Completion (ACTUAL): April 30, 2022

Study Registration Dates

• First Submitted: October 23, 2021
• First Submitted That Met QC Criteria: November 17, 2021
• First Posted (ACTUAL): November 30, 2021

Study Record Updates

• Last Update Posted (ACTUAL): October 26, 2022
• Last Update Submitted That Met QC Criteria: October 25, 2022
• Last Verified: October 1, 2022

More Information

Terms related to this study

• Keywords: Hemiparetic Gait; Robotic Knee Exoskeleton
• Additional Relevant MeSH Terms: Nervous System Diseases; Neurologic Manifestations; Paralysis; Hemiplegia; Paresis
• Other Study ID Numbers: REFLEX_HemipareticEMG

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.
• IPD Sharing Time Frame: Immediately following publication, no end date
• IPD Sharing Access Criteria: Access will be subject to methodologically sound proposals and it will be approval by scientific investigator (julio.lora@csic.es)
• IPD Sharing Supporting Information Type: CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No