New exoskeleton is the first to stimulate paralysis patients' muscles electrically, an effective therapy

While stem cell therapies could provide a true "cure" for paralysis in humans in decades to come, in the shorter term, wearable robotics could provide an effective stopgap therapy.  Several industry and research groups have been developing robotic "exoskeletons", which offer load-bearing walking motions.  In able-bodied humans, the skeletons can help workers carry heavier loads without joint stress.  But in paraplegics the promise is even greater -- the exoskeletons could allow them to "walk" again.

I. Building a Cheaper, Better Medical Exoskeleton

Currently, so-called "rehabilitative" exoskeletons are available to paraplegics, but they remain relatively expensive -- costing $140,000 USD or more.  With that problem in mind, researchers at Vanderbilt University's Center for Intelligent Mechatronics have designed a new "minimalist" robotic rehabilitative exoskeleton, and are working with Parker Hannifin Corp. (PH) to produce the device at a lower cost.

The device will compete with at least two other companies -- Argo Medical Technologies Ltd. in Israel and Ekso Bionics in Berkeley, Calif. -- for an estimated market of 236,000 to 327,000 patients in the U.S. suffering from severe spinal injuries.

The system is pretty standard, complete with hip and knee joints, which are robotic motors powered by rechargeable batteries.  Unlike more ambitious, but more expensive designs, the system is not capable of solely maintaining balance.  Paraplegic users will use the suit (which straps on around the waist and over the shoulders) to walk, but they'll have to use crutches to help maintain balance.

Mechanical engineering professor Michael Goldfarb describes, "You can think of our exoskeleton as a Segway with legs.  If the person wearing it leans forward, he moves forward. If he leans back and holds that position for a few seconds, he sits down. When he is sitting down, if he leans forward and holds that position for a few seconds, then he stands up."

Brian Shaffer, a paraplegic since 2010, tested the suit at a satellite facility in Nashville, Tenn.  He recalls, "My kids have started calling me 'Ironman.'  It's unbelievable to stand up again. It takes concentration to use it at first but, once you catch on, it's not that hard: The device does all the work. I don't expect that it will completely replace the wheelchair, but there are some situations, like walking your daughter down the aisle at her wedding or sitting in the bleachers watching your son play football, where it will be priceless."

II. Physical Therapy Success, Lays Groundwork for Home Use

An important note is that the device and its peers still are not geared for home use; they're targeted at a rehabilitative (think doctor's office) setting.  But in terms of devices in that environment, the new exoskeleton appears very competitive.

The suit and similar models are not only liberating to the paralyzed; they can also cut down on serious health issues caused by sitting for prolonged periods in wheelchairs.  It's light -- only 27 lb (versus the common weight of around 45 lb) -- and slim.  The modular and minimalist design allows it to be folded up and transported on the back of a wheelchair.

The device also incorporates two other rehabilitative advances.  First, it's capable of detecting users' muscle movements.  That means in users with reduced capability, but not complete leg paralysis, the device can provide a less powerful amount of resistance.  This "just enough" approach can help prevent joint damage in partially paralyzed individuals.

Vanderbilt exoskeleton
Vanderbilt's new exoskeleton is lighter than its rivals and bakes in new capabilities.
[Image Source: Vanderbilt/Parker Hannifin]

Second, the device claims to be the first exoskeleton to apply small electrical pulses to paralyzed muscles, causing them to contract and relax.  This approach -- functional electrical stimulation (FES) -- has been shown to improve circulation, change bone density, and reduce muscle atrophy in victims of paralysis.

Clare Hartigan, a physical therapist at Shepherd Center, the medical center that helped test the device, did offer a warning for paraplegics that walking again wasn't as easy as they might hope -- it's a real workout.  She states, "These new devices for walking are here and they are getting better and better. However, a person has to be physically fit to use them. They have to keep their weight below 220 pounds, develop adequate upper body strength to use a walker or forearm crutches and maintain flexibility in their shoulder, hip, knee and ankle joints ... which is not that easy when a person has relied on a wheelchair for months or even years."

Still, it's thrilling to watch iterative refinement of robotics exoskeletons for rehabilitation, a success that is almost surely a prelude to even more liberating exoskeletons for home use.

The suit design work was funded by a grant from the National Institutes of Health (NIH).  Its other key contributors were research engineer Don Truex, graduate students Hugo Quintero, Spencer Murray and Kevin Ha, and Ryan Farris, a former student who now works for Parker Hannifin.

Sources: Vanderbilt [press release], [video]

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