Walking with Paralysis

Strapped into an exoskeleton, Damyane Evely strode heavily back and forth across a 15-foot platform, taking an occasional peek at a monitor on the wall to survey his progress — and to silently marvel. It had been more than 15 years since his spinal cord was compressed in a motorcycle accident, landing him in a wheelchair. He was relishing his verticality.

Last December, Evely was the first person in the U.S. with a spinal cord injury to test the new, self-balancing Wandercraft Atalante, a third-generation exoskeleton with 12 degrees of freedom that is designed to more closely approximate human gaits than current models. He took 1,100 steps that day in Saikat Pal’s Life Sciences Motion Capture Laboratory, with a group of engineers, physical therapists, exoskeleton trainers and robot designers looking on. They wanted to know not just whether he could walk in it, but how naturally and safely.

Sections of both Evely’s body, from his head to his toes, and corresponding points on the exoskeleton were tagged with reflective markers that light up under infrared sensors positioned around the lab. A network of cameras continuously recorded those movements, feeding the data into a specialized software program that displays an avatar on the monitor, while also recording the forces from the ground to determine their impact on joint rotations for both human and robot.

Using the markers, the researchers are able to track the 3D movement of each body segment with respect to a reference frame at the center of the platform. This allows them to calculate the relative movements of each body segment with respect to one another — the wrist to the elbow, the elbow to the shoulder, for example.

“We were measuring the movement of the human and the robot, both together and independently, to see how the two interact and to get a deeper sense of the physics behind how a human walks in the robot,” says Pal, a biomedical engineer. “With the Wandercraft and other models, we also want to know how the device improves a host of health measures in different patient populations.”

Not being able to walk is just one of the problems that people with spinal cord injuries (SCI) face. Bone density and strength, bowel function, psychological state and cardiovascular health are among the many aspects negatively affected by losing upright ambulation.

“Taking 1,100 steps is very good exercise for people with SCI and great for their health,” Pal says of Evely’s session. “By the end, Damyane was sweating.”

The Department of Veterans Affairs has committed to providing an exoskeleton to every eligible veteran with SCI who wants one. So far, the U.S. Food and Drug Administration has approved three devices for use, not including the Wandercraft. Pal is testing their safety.

“There are some negative impacts on weak bones, as is often the case with chronic SCI. Exoskeletal-assisted walking trials have reported fractures at the knee and ankle,” he notes.

Backed by a $1.2 million grant from the Department of Veterans Affairs to evaluate individuals with SCI in the FDA approved exoskeletons, Pal is developing methods to predict the risk of fractures by determining the mechanical competence of bone and forces brought to bear on the joints during exoskeletal-assisted walking. This grant is in collaboration with the James J. Peters VA Medical Center in the Bronx. Pal works closely there with William A. Bauman, M.D., Cong Wang, director of the VA Rehabilitation, Research and Development National Center for the Medical Consequences of Spinal Cord Injury, and Ann Spungen, Ph.D., associate director of the Spinal Cord Damage Research Center and the principal investigator for its exoskeletal-assisted walking program.

“The human is the most important component of this system. We need to determine the forces they’re experiencing at their joints so we can reduce them and minimize fractures,” he says.

As they develop new and improved models, safety and fluidity will determine their success.

“We don’t want people moving like Frankenstein. People who need these devices want to blend in with the crowd,” says Pal. “We also recognize that the patient population is not generic. Two people with the same diagnosis, say a thoracic-4 injury, may have very different functionalities, not to mention body dimensions.”

Exoskeletons of the future, he says, will come with degrees of personalization with respect to weight, height and gait patterns. Using AI, designers will be able to customize their trajectories to optimize the robots’ performance.

For Evely, the test alone was worth the effort.

“Just to stand, to have an eye-level conversation, makes it worthwhile,” he says of the trial, adding, “It’s not going to cure my paralysis, but I’ll do anything for science and research that moves us forward. I’m all for it. I’m looking forward to the day when I can stand and hug my sons.”

Watching him, Pal shares, was a peak moment in his career.

“For someone who is paralyzed to get up and walk around, more or less independently, in just one session, was the coolest.”