Human-Machine System for the H2 Lower Limb Exoskeleton

Stroke is the leading cause of neurological disability in the United States and accounts for
the poor physical health and the social dysfunction evident in survivors. Gait impairment is
a large contributor to long-term disability and ambulatory function in daily living. Many
patients, however, lose the ability to walk independently, and furthermore, a large
proportion does not regain their normal walking speeds following a stroke. In this context,
newer robotic-aided therapeutic tools such as "wearable" lower-limb robotic exoskeletons
have been developed, which allow for the user to be augmented by mechanically actuated lower
limb joints that can either completely or partially assist movements of the lower limb
segments depending on the patient needs.

The H2 exoskeleton (developed by Technaid S.L., Spain) is an example of one such system that
has hip, knee and ankle joints actuated for both lower limbs. These devices are very new,
and therefore, systematic investigations of therapeutic benefits of these devices are
lacking in the field. Further, the nature of plasticity in the brain triggered by wearing
and training such exoskeletons is unknown. In this exploratory research study, the
investigators aim to compare robotic-assisted rehabilitation using the H2 exoskeleton with
supervised motor practice particularly in terms of functional recovery. Additionally, this
study will also examine brain plasticity associated with robotic-assisted training using
non-invasive scalp electroencephalography (EEG) and changes in lower limb joint kinematics
during robotic-assisted training. Taken together, the findings from this research will be
used to understand human-robot interaction and to design smart powered orthotic devices that
can be controlled directly by brain activity and assist those that have lost all or part of
their walking abilities due to neurological disease or injury. Moreover, this study will
systematically track neuroplasticity associated with functional recovery after stroke, which
will help determine optimal windows for treatment that would maximize therapeutic benefit.
Lastly, it will also help characterize markers of learning to use these new devices, which
will be important in the clinical setting for modifying and adapting rehabilitation
protocols to suit changing needs of the patient (user).

Inclusion Criteria:

- Sub-acute or chronic stroke i.e., interval of at least 3 months or interval of at
least 6 months from stroke to time of enrollment, respectively;

- Cognitive ability to assimilate and participate actively in the treatment protocol
(Mini Mental State Examination score > 24 points, out of a total 30 indicating normal
cognitive ability);

- Modified Rankin scale scores 2-4 (Mild-Moderate functional disability post-stroke);

- Modified Ashworth Scale of Spasticity score <= 2 (ranges from 0-4 with 4 reflecting
maximum spasticity);

- Have no skin integrity issues;

- Sufficient passive range of motion at the hip (at least 90 deg flexion, 15-20 deg
extension), knee (90 deg flexion, complete extension) and ankle (15 deg dorsiflexion,
15 deg plantarflexion);

- Have no contraindications to standing or walking; able to stand with assistive device
for at least 5 minutes, and able to walk with assistive device for 10 m.

Exclusion Criteria:

- Severe cognitive and/or visual deficit;

- Hemineglect (determined based on medical record or initial clinical assessment);

- Severe sensory deficit;

- Joint contractures of any extremity that limits normal range of motion during
ambulation with assistive devices;

- Skin lesions that may hinder or prevent the application of exoskeleton;

- Uncontrolled angina;

- Severe chronic obstructive pulmonary disease;

- Other medical contraindications; any medical co-morbidities that would prevent
standard rehabilitation.

Inclusion criteria for healthy, able-bodied participants:

- Able to understand and sign the consent form

- Age 18-75 years

Exclusion criteria for healthy, able-bodied participants:

- History of neurological, neuromuscular or physical disability.