Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT05138185 |
| Other study ID # |
REFLEX_TechValidation |
| Secondary ID |
|
| Status |
Completed |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
February 15, 2021 |
| Est. completion date |
April 20, 2021 |
Study information
| Verified date |
November 2021 |
| Source |
Spanish National Research Council |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
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 behavior 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 generate the assistance according
to two differents strategies: (1) Replicating the movement of the helathy leg or (2) Inducing
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. We aim 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.
Description:
- Brief name: Proof-of-concept of a unilateral robotic knee exoskeleton and evaluation of its
effects over gait symmetry.
- 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 following two different control
strategies: (1) Replicating the movement of the sound leg (Echo Strategy) or (2) Inducing a
healthy gait pattern on the paretic leg (Pattern strategy). The action of the robot depends
on the gait phase of the assisted leg: during stance 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: Subjects were instructed to walk on a treadmill at a constant speed during
trials of 5 minutes. All subjects carried out four different kinds of trials: (1) NoExo:
subjects only wore the inertial sensors and the insole pressure sensors to acquire their
basal motion; (2) Free: subjects wore the exoskeleton although the actuator was mechanically
decoupled, so it enabled the free movement of the knee; (3) Echo: the device provided gait
assistance following the Echo-control strategy; and (4) Pattern: the device provided gait
assistance following the Pattern strategy. During trials, patients wore a safety harness,
although it did not support any weight. Previously to the execution of the trials, the gait
velocity was self-selected by the subjects to a comfortable level. Subjects rested between
trials for five minutes at least, in order to avoid adaptation and learning effects from
trial to trial.
Healthy subjects also performed a previous trial under variable gait speed (VariableSpeed).
They walked over the treadmill as in the NoExo condition, although the gait speed randomly
varies from 1km/h to 3km/h in 0.2km/h steps for 15 seconds at least.
- Intervention providers A physiotherapist and an engineer are present during the trials. The
first is responsible of assessing the basal gait of the subjects and evaluating his/her state
while the assistance is provided. The engineer is 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 gait speed for the trials.
