This study seeks to test the safety and efficacy of the Esko device in SCI population and in populations with similar neurological weakness to the SCI population. The device can currently stand from a seated position, walk, and turn and sit down. Our hypothesis are as follows:

• Hypothesis 1: We hypothesize that the Ekso subject will significantly improve balance while wearing the device as noted by subject's ability to safely achieve standing balance for 30 sec without loss of balance.
• Hypothesis 2: We hypothesize that the Ekso subject will display improved ability to safely ambulate 10 meters to be assessed using the 10 meter walk test.
• Hypothesis 3: We hypothesize that the Ekso subject will display improved weight shift in both static and dynamic activities as determined by a trained physical therapist.
• Hypothesis 4: We hypothesize that the Ekso subject will verbalize improved success with training of the device as noted by subjective questionnaires that will be assessed following each training session.

This is an investigational clinical study trialing the safety and efficacy of the Esko device in the SCI population. Participants with a variety of spinal cord injury diagnoses (e.g. motor complete/incomplete, paraplegia/ tetraplegia) or diagnoses presenting with similar neurological weakness will be included to best determine the criteria for using the Ekso device within this population. The Ekso is an anthropomorphic mobile exoskeleton that is intended for spinal cord injury rehabilitation and mobility. The device is used to drive the patient's lower extremity joints through a desired trajectory in order to obtain a user specified motion.

The device is electrically powered by two motors at the knee and hip joints of either leg of the user. The flexion and extension directions at the hip and knee are only actuated degrees of freedom on the device. The device is equipped with mechanical hard stops at the limits of healthy subject ranges of motion to prevent powering the joint of the user to a position that the joint cannot reach. The device operates using a number of sensors. Some of these sensors are dedicated to maintaining proper function of the mechanical system and some are devoted to determining the user intent while using the device. The user focused sensors are foot pressure sensors at the heel and toe of both feet to determine the forces between the user and the ground at those locations.

The control code in the device behaves by creating an internal estimate of the subject's current position and then coordinating the motion of the four actuated degrees of freedom to take the desired motion. The desired motion is specified through an attached user interface that can be used by the patient or a therapist. The device can currently stand from a seated position, walk, and turn and sit down. In actual operation the device is triggered by one of two modes. The first mode is used early in training where the therapist manually triggers the steps of the user using the graphical interface; for advanced users, the machine interprets their motions to determine when steps are desired and the therapist is only responsible for starting and stopping the motion.

Complete and incomplete SCI patients as well as patients with similar neurological weakness will be recruited from inpatient, day rehab and outpatient clinics. Participants will be scheduled from 1-40 sessions. The amount of sessions provided will be dependent upon compatibility with device, ability to tolerate device use and ability to safely ambulate using the device. A participant will continue with each phase of the study as deemed appropriate by research staff:

• A.Phase 1 (1-3 sessions): To determine if participant is compatible with device use. If participant is not compatible with device the study will stop here. If participant is compatible with device, subject will move into phase 2.
• B.Phase 2 (4-10 sessions): Assessment and training of participant with device to determine safety and efficacy of subject with device. If subject is unsafe with device or does not tolerate device well then the study will stop here. If participant is safe, comfortable and efficient with device, participant will move into phase 3.
• C.Phase 3 (11-40 sessions): Continued training with participant to determine functional ability of patient to use device within a lab or clinical environment.

All testing and training sessions will be under supervision of a licensed physical therapist. Manual assistance or cueing will be provided as necessary for safety and balance. Vital signs will be monitored before and after physical exertion. All subjects will be permitted to stop physical activity or rest at any time during the study. Adverse events will be recorded.

We anticipate this study will help to determine if the Ekso device is a feasible option to initiate ambulation in the motor complete SCI population, motor incomplete SCI population and other similar diagnostic populations unable to ambulate over ground. We do not foresee any potential pitfalls.

Inclusion Criteria:

Participants must:

• have a spinal cord injury SCI between C7-S1.
• be between 18-65 years of age.
• be able to physically fit into the exoskeletal device.
• be able to tolerate upright standing for a minimum of 30 minutes.
• have joint range of motion (ROM) within normal functional limits for ambulation.
• have sufficient upper body strength to balance themselves using the walker while wearing the exoskeleton.
• have a different neurological weakness than SCI but fit the other inclusion criteria above

Exclusion Criteria:

• Height below 62 inches or above 74 inches
• Weight above 220 lbs.
• Joint contractures of any extremity that limits normal ROM during ambulation with assistive devices.
• Any medical issue that precludes full weight bearing and ambulation (e.g. orthopedic injuries, pain, severe spasticity)
• Skin issues that would prevent wearing the device.
• Cognitive and/or communicative disability (e.g. due to brain injury). Patients must be able to follow directions well and demonstrate learning capability.
• Significant Osteoporosis: Osteoporosis will be graded based on the T score that indicates a person's bone mineral content and is graded as follows: (14)

T +1: Normal bone density:

• T -1 to -2.5: Low bone density of osteopenia
• T -2.5 to -3.0: osteoporosis
• T <-3.0: Severe osteoporosis
• If the patient has severe osteoporosis and a T score of <-3, participation in the study will be considered based upon their physicians recommendation and overall evaluation of the patient.