Paraplegic Patient Tests a Medical Exoskeleton

Helping paralyzed people and those with spinal injuries to stand and walk

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This segment is part of the IEEE Spectrum series “The New Medicine

Susan Hassler: The word exoskeleton may make you think of bugs and your high school biology class. But these days, exoskeletons are also the cutting-edge robotic suits that people can strap onto their bodies to augment their normal abilities. Some exoskeletons are being developed for the military, to let soldiers carry heavier loads or walk farther. Another kind allows paralyzed people to stand up and walk again. Eliza Strickland visited a hospital to watch a paraplegic patient try using a medical exoskeleton.

[ambient laboratory sounds; man at clinic: “Okay, you ready?”; sounds of Robert Woo walking in the exoskeleton]

Eliza Strickland: We’re in a crowded rehab room at New York City’s Mount Sinai Hospital, where Robert Woo is taking slow, halting steps. That’s pretty remarkable for a man who is paralyzed from the waist down. Woo lost the ability to walk four years ago when he was injured in a construction accident.

Robert Woo: It was a crane accident in New York City. It happened December 14, 2007. I was the architect for the new Goldman Sachs world headquarters in lower Manhattan. I was in my trailer, finishing off a site visit. And 7 tons of steel fell from about the 25th or 30th floor onto my trailer. I was crushed from [the] neck down.

Eliza Strickland: Now Woo is on his feet, held up by a pair of sleek, mechanical legs that are strapped to his own legs. This exoskeleton device does the walking for him by supporting his weight and bending his knees and hips in sequence to produce natural-looking steps. Leading U.S. rehabilitation hospitals will soon be using these exoskeletons, which make it possible for spinal injury patients to put on their walking shoes. Robert Woo is trying out the device, which is called the Ekso, during its one-week demonstration at Mount Sinai. He says he was plenty nervous at first.

Robert Woo: It was scary standing up, because I didn’t know what to expect. I didn’t have any confidence in it. It was a new device; I was worried about falling or injuring myself.

Eliza Strickland: But Woo is making rapid progress. During his first 1-hour session at the rehab clinic, he trained with a wheeled walker. By his third session, he is already marching up and down the room using two walking sticks, or crutches, for balance.

[laboratory ambience; people at clinic talking: “Crutches forward…crutches forward…. Nice job…. That was pretty good. You looked like you trusted it there a little bit”]

Eliza Strickland: The Ekso is built by a Berkeley, California, company called Ekso Bionics. I visited the company’s headquarters on a tree-lined suburban street in West Berkeley, where modest bungalows alternate with industrial buildings. Inside the company’s cavernous warehouse, dozens of pairs of legs dangle from ropes like the bottom half of a robot army.

Nathan Harding: This is both our manufacturing space and our engineering test space. We get to do all sorts of crazy things with Eksos right here.

Eliza Strickland: That’s Ekso Bionics cofounder Nathan Harding, casually dressed in jeans and a T-shirt, who shows me around. We stop by one Ekso system that is undergoing a durability test, taking step after step in the empty air. Harding explains how the system works.

Nathan Harding: The Ekso is essentially a pair of robotic legs that you strap on. It both carries its own weight, and it provides torque to the joints of your legs, just like your muscles would, to allow you to stand up and carry your weight on your bones the way someone who hasn’t had an injury would. It uses servomotors at the hips and knees to move the body in a natural gait.

Eliza Strickland: The plastic and aluminum legs do the heavy lifting, but exoskeleton users like Robert Woo have a lot to learn about making the devices work for them. Woo has to balance his torso above the robotic legs and shift his weight from side to side in preparation for each step. He also manages two walking sticks, which help with balance. Because a patient must have upper-body strength to use the Ekso, this technology can’t help all paralyzed people. But Ekso Bionics does plan to expand its customer base beyond people with spinal cord injuries and hopes to start working with both multiple sclerosis and stroke patients soon.

Nathan Harding: There are more than 2 million people in the U.S. who use wheelchairs. If you can even get a small percentage of those people up and walking in Eksos, you’ll have done a lot of good.

Eliza Strickland: In the current Ekso system, the physical therapist uses a remote control to trigger each step of the robotic legs. But with the next-generation model, users will have upgraded walking sticks with embedded motion sensors to control their own steps. Moving the right crutch forward signals the left leg to step forward and vice versa. In time, says Harding, even that user control system will be outdated.

Nathan Harding: There’s a lot of talk about long-term solutions and direct interfaces to [the] brain, to other parts of the nervous system. Which of course are extremely exciting, and they’re inevitable in the human exoskeleton business, but the key right now is to pick a path that gets people up and walking as soon as possible and lets them do what they need to do.

Eliza Strickland: Can exoskeletons really change people’s lives? Back in New York, I talked with Dr. Kristjan Ragnarsson, chairman of the department of rehabilitation medicine at Mount Sinai Hospital. He’s been in the business a while.

Kristjan Ragnarsson: I have been treating people with spinal cord injury for almost 40 years. The first thing that occurs to most of them is whether they will walk again. And as their physician, I always have to address that question.

Eliza Strickland: Over the years, Ragnarsson says he’s seen a wide range of high-tech gadgets that were intended to let paralyzed people walk again. All of them failed, he says, because the patients had to exert far too much energy to walk in the devices.

Kristjan Ragnarsson: It’s like if you were running the 100-yard dash all the time—they are completely exhausted after just a few steps.

Eliza Strickland: Ekso is different, he says, because it uses external power to help the patients move their paralyzed limbs.

Kristjan Ragnarsson: As a physician for these patients, I’m hopeful that that will indeed reduce the energy consumption to the extent that they will be able to ambulate or walk. That doesn’t mean they won’t need training. They will need extensive training, because to operate this kind of system successfully, you need to be pretty nimble, pretty smart, highly motivated, and in good shape besides your paralysis. But I’m optimistic, actually, that this will work.

Eliza Strickland: Ekso Bionics plans an ambitious rollout. First comes the device that will allow patients to train at rehab hospitals. Later on, the company will introduce a version that can be used for at-home physical therapy. Robert Woo says he thinks the Ekso will have both physical and mental benefits for him.

Robert Woo: It definitely will make a difference in my life. I already feel very energetic. I think the biggest thing is the emotional feeling of being able to stand and walk. With this bionic system, it makes you feel like you can walk again—like you used to, before your accident.

Eliza Strickland: Within the next few years, Ekso Bionics plans to have a version ready for everyday use—a pair of robot legs that will allow people to ditch their wheelchairs for hours at a time and get on with the business of living. Woo says that as he trains with the Ekso and gets better at using the walking sticks, he’ll be dreaming of that day.

Robert Woo: I look forward in the future that I will be able to walk with the crutches but also cook with it, do things! Walk in the park with my children.

Eliza Strickland: I’m Eliza Strickland.

Photo: Ekso Bionics

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