Keeping the X in Exo

Posted by Sam Maddox in Research News on April 12, 2016 # Research, Technology

I promised myself I wasn’t going to write about exoskeleton devices for a while but they keep jumping in front of me.

Last week, a third exoskeleton device was approved by the FDA, the GT from Ekso Bionics, the Bay Area California company that pioneered the idea of robo-bionic ambulation. The news here is that for the first time the device addresses not just spinal cord injured paraplegics with injuries at T4 to L5 but also those with incomplete spinal cord injuries at T3 to C7 (so-called ASIA Ds). Most significantly, Ekso is targeting patients with hemiplegia due to stroke. Stroke is a much sweeter market than SCI -- the company says it is almost 50 times as large.

The Ekso joins ReWalk and Indego, two competing units targeting spinal cord injury. See recent coverage here.

While ReWalk and Indego are hoping to sell $75,000 units directly to consumers, and are angling to get insurance coverage, Ekso is going to stick with a strategy of using exoskeletons for rehab in clinical settings.

From an Ekso press release:

Ekso GT is a wearable robotic exoskeleton that enables individuals to stand up and walk over ground with a full weight bearing, reciprocal gait in a clinical setting. The Ekso GT with smart Variable Assist software, which was designed for rehabilitation institutions, provides adaptive amounts of power to either side of the patient’s body, engaging the patient throughout his or her continuum of care. The technology provides the ability to mobilize patients early in their recovery, frequently, with a significant number of high intensity steps. To date, the Ekso has helped patients take more than 41 million steps in over 115 rehabilitation institutions around the world.

Part Two. Better than the Movie?

If you get the Sunday New York Times maybe you saw this. Page 13 of the Magazine sports a full page advertisement for Mount Sinai Rehab. It’s mostly text over a hazy grey, with a small figure at the bottom of the page. It’s dawn, a new day, and obviously he’s a guy in rehab, wearing something on his legs and using crutches. The headline: Bionic Exoskeletons can be found in comic books, Hollywood movies, and now at Mount Sinai.

There’s a little bit of text at the top, telling us about spinal cord injured Robert Woo, a Manhattan architect “crushed by seven tons of falling steel.” Let’s assume that’s him, ready to step into his robotic future. “His injuries were devastating. But thanks to the Mount Sinai Department of Rehabilitation, he’s walking again with help from a bionic exoskeleton strapped to his legs. Proof that sometimes, real life is even better than the movies.” Really? In the movie in my head, and in the ad I’d like to see, Woo is standing on a horizon, but you can’t tell he’s wearing a robot device.


Woo’s story was widely reported back in 2007 when a crane accident at the new Ground Zero headquarters for Goldman Sachs buried him under all that steel. Woo apparently wasn’t handling paralysis real well for a number of years but regained both physical and emotional health, he says, after participating in 2013 Mount Sinai clinical trial for the Ekso. In 2015, Woo was the first person to be certified to purchase the newly approved ReWalk Personal 6.0 System for home use (BTW he could afford it: it was reported on a NY legal website that Woo settled a lawsuit for $20 million).

What Woo says, that he gets an emotional benefit from being upright, that’s pretty much the case for a lot of the many early test pilots for exoskeletons, at least the ones we read about in company news releases. Being upright, loading the bones, looking eye to eye with others, these are all cool aspects of robowalking. Mark Pollock, a member of the Reeve Foundation Board of Directors, is a paraplegic who uses an Ekso daily as part of an experiment combining robotics and non-surgical spinal cord stimulation (covered here and here). He puts the attraction this way: “From a personal perspective I’ve noticed two big positives with Ekso. I just feel better every time I walk and that psychological lift is positive in itself. Physically there is a clear impact. After each session the small spasms that I get in my legs disappear and the dull pain in my back lifts. In short, I feel both mentally and physically better after walking every time.”

Part Three, the Evolving Literature

I reported in recent posts that the medical literature regarding exoskeletons in SCI rehab is pretty thin, despite claims by the exo companies that it’s not about walking but about improved health benefits in other body systems. A group from the Miami Project noted in 2014 that some users of exos have reduced neuropathic pain. See “Understanding therapeutic benefits of overground bionic ambulation: exploratory case series in persons with chronic, complete spinal cord injury.”

Another paper has just come out that may add weight to the case that exo-users get a health bump. The paper is titled “Clinical effectiveness and safety of powered exoskeleton-assisted walking in patients with spinal cord injury: systematic review with meta-analysis.”

Meta-analysis looks at a range of papers that have been published on a given topic and attempts to extract common data points to form sort of a “big picture” analysis. In this case, they rounded up 14 exoskeleton studies -- eight with ReWalk, three with Ekso, two with Indego, one unspecified, representing 111 patients. Conclusion: “... powered exoskeletons allow patients with SCI to safely ambulate in real-world settings at a physical activity intensity conducive to prolonged use and known to yield health benefits.”

From the paper:

Training programs were typically conducted three times per week, 60–120 minutes per session, for 1–24 weeks. Ten studies utilized flat indoor surfaces for training and four studies incorporated complex training, including walking outdoors, navigating obstacles, climbing and descending stairs, and performing activities of daily living. Following the exoskeleton training program, 76% of patients were able to ambulate with no physical assistance. The weighted mean distance for the 6-minute walk test was 98 m. The physiologic demand of powered exoskeleton-assisted walking was 3.3 metabolic equivalents and rating of perceived exertion was 10 on the Borg 6–20 scale, comparable to self-reported exertion of an able-bodied person walking at 3 miles per hour. Improvements in spasticity and bowel movement regularity were reported in 38% and 61% of patients, respectively. No serious adverse events occurred.

There you have it. Spasticity reduced and bowel function improved.

The paper appeared in the journal Medical Devices, from Auckland, N.Z., not a citation I’ve come across before. The lead investigator, William G. Herbert, is not someone familiar in the exoskeleton world; he’s Professor Emeritus of Human Nutrition, Foods, and Exercise at Virginia Tech. First author is Larry Miller, who owns Miller Scientific Consulting, in North Carolina. Herbert is listed as a consultant for Miller, whose business contracts with academia and industry to place medical information into the literature. I notice that the study was paid for by ReWalk.

If you are at all familiar with the way academic publishing works, you know about the pecking order; in the life sciences, Nature and Science are the top dogs and therefore have the highest “impact factor,” and on down the list you go, hundreds of journals deep, until you get to a murkier area of scholarship, the so-called open source journals. Open source is a great idea – anyone can access the research, not just those who can pay high subscriptions fees. The business model is that the person or group submitting the paper pays a fee to the journal – often around $2000 – and the journal arranges some sort of peer review and then posts the article online. Medical Devices, owned by Dove Medical Publishing, is an open source, pay-for-publishing journal. That’s not to damn this particular exoskeleton paper, or the open source concept, but it provides an example of how industry bias can be introduced into the research literature.

How rigorous is the open source process? You may wonder, are real peers actually reviewing the text? Is pay-to-play science publishing in open source journals legit? It is, for the most part. The most prominent open source journal is PLOS (for Public Library of Science). It runs seven journals, including PLOS Biology, which we come across a lot in the neuroscience field. I’ve heard it said it’s not a good career move for an academic to have too many papers in PLOS, but it’s not lacking in credibility.

Maybe you remember this great open source sting from a couple of years ago. John Bohannon, a freelance writer who’s also a Harvard biologist, wrote an article for Science that exposed a deceitful and predatory side of academic publishing. He totally made up a paper describing how a chemical in lichen could slow cancer cells. He submitted it to 304 peer-review journals. The paper was a total clunker, so bad, said Bohannon, that "any reviewer with more than a high school knowledge of chemistry … should have spotted the paper's shortcomings immediately. Its experiments are so hopelessly flawed that the results are meaningless."

The paper was accepted for publication at 157 journals, all open-access. PLOS did not fall for it; a journal called Drug Design, Development and Therapy did accept it. This publication is owned by Dove Medical Publishing.

Dove got kicked out of the Association of Learned and Professional Society Publishers, an umbrella that strives to keep open source legitimate. Dove has since convinced the society that its peer review systems are for real; they have rejoined the group.

OK, does any of that matter? Maybe not. The exoskeleton industry needs rigorous data to justify asking insurance companies to pay for $75,000 devices. Industry is willing and able to pay for the research. Let’s just leave it here: the benefits of exo use are still evolving.