Advertisement
Tech by VICE

This Prosthetic Arm Can Move and Feel Almost Like the Real Thing

A modular prosthetic limb provides one woman with 'as near a normal arm as there’s ever been in the history of amputations.'

by Joseph Neighbor
Aug 15 2016, 10:10pm

Written by Joseph Neighbor

On a Saturday morning last July, Melissa Loomis woke early to let her dogs out. Groggily, she was standing on her patio, scrolling through her phone, when she heard a terrible hissing noise. Her two dogs had cornered a raccoon atop the fence. When they grabbed it by the tail and pulled it off its perch, Loomis intervened, grabbing hold of the raccoon and tossing it over the fence. In the melee she got a few scratches and a bite on her right arm.

By this time, her husband has heard the commotion and came outside. "I was standing there with blood dripping down both of my arms," said Loomis. "I said I got into an argument with a raccoon. I was obviously just totally in shock. I said, 'do people still get rabies shots these days?'"

She went to the hospital for a round of shots, and was sent on her way with an antibiotic. It didn't seem like a big deal. She returned to work at the retirement community where she's been employed since high school, over 20 years ago, first as a waitress, and now as food director.

But a few days later, the pain in arm had only increased. It grew swollen and hot. She went to a local stat care place, and then the ER. More antibiotics, no results. After another week, a surgeon opened her arm to drain it of infection, and it was clear something wasn't right. The infection oozed like "tapioca pudding," as Loomis described. She was immediately admitted to the hospital.

Thus began a nightmarish 29 days, during which she underwent 10 surgeries, went septic, nearly died when her kidneys and liver started to shut down, and ultimately had her arm amputated just above the elbow. This last part was not anticipated by anyone, especially Dr. Ajay Seth, the orthopedic surgeon who took over her case and performed each of the operations.

"Every surgery was to try to save her arm," Dr. Seth said. "Amputating a 43-year-old's arm is not something you want to do. And I've never had to do that for an infection. It's something I've always been able to get rid of hundreds of times."

But after having carved away at the infected flesh until barely anything remained, there was no alternative save amputation. "I didn't really want to make eye contact with her," said Dr. Seth, recounting the day he had to break the news. "I remember turning around and I was almost in tears. I said I tried to save your arm but I couldn't do it. And she said, you tried your best now please save my life."

The amputation did indeed save Loomis' life. But that life was now radically different. Everyday tasks like cooking dinner can no longer be done alone. Taking a shower takes twice as long. Tying shoelaces or fastening buttons, little things one doesn't think of much, were now frustratingly difficult. She used to volunteer at the dog pound every weekend. Now she goes to physical therapy to learn how to adapt to her new condition.

"In my brain, I still have a hand," Loomis said. "I can feel it. I can move it. It's sort of surreal, because I'll go to grab my car keys, and go, 'oh crap.' In one aspect, it doesn't feel any different. In another aspect, everything is different."

These annoyances were compounded by the severe, relentless pain in her phantom limb. As she describes it, her hand feels like it's floating up near her elbow, without a forearm. "It feels like my hand is clenched in a fist, and I can't open it at all," she said. "It was being crushed in a vice."

The amputation weighed heavily on Dr. Seth. In the months after the surgery, he grew quite close to Loomis and her family. Though her arm couldn't be saved, he vowed to do everything in his power to restore as much normalcy to her life as possible.

Last fall, a few weeks after the amputation, he attended a medical conference in Seattle. There he saw a presentation on a novel surgery called Targeted Sensory Reinnervation (TSR). Pioneered by Dr. Jacqueline Hebert of the University of Alberta, TSR has only been attempted a few times in Canada and Italy, but never once in the U.S. But the results were promising.

It's based on a similar surgery called Targeted Muscle Reinnervation (TMR), which has been performed hundreds of times around the world. TMR works like this: After an amputation, the nerves that control a hand's movement continue to fire signals down to the absent limb. This is the source of phantom pain. By re-attaching those nerve-ends to another muscle—a bicep or pectoral, for instance—those signals have somewhere to go, completing a circuit that relieves the pain.

So when a person thinks of, say, pinching their thumb and index finger, those neural signals now travel to wherever the nerves were re-routed. Those neural signals can be discerned by electrodes attached to the skin, and then mapped and patterned by software. They can also be relayed wirelessly to one of the groundbreaking mechanical prosthetic arms currently in development, allowing the user to operate a bionic limb with their mind.

TSR is essentially the same idea, but it isolates the two specific nerves that relay the sensation of touch. Ideally, both surgeries would be done at the same time. Theoretically, not only could the user send signals to prosthetic arm via the nervous system, but also the sensors on that bionic arm could send tactile information back to the brain, thus completing the loop. It's a game changer.

Dr. Seth decided he wanted to give both surgeries a go. Loomis consented. "Sure, why not?" she said. "I've had 10 surgeries already—what's one more?"

Dr. Seth reached out to Dr. Hebert, who put him in touch with a surgeon who had performed the operation and could walk him through it. On December 10th, Loomis went under the knife. The surgery lasted 16 hours. As Dr. Seth describes it, a nerve is like a piece of licorice, in which many strands are braided together. Not only did he have to find and re-route the motor nerves, but he also had to tease out the two specific, tiny sensory nerves. It's an exceedingly tedious, delicate process.

And it worked. When she awoke, Loomis reported that, for the first time since that raccoon bit her, she felt no pain. "And I really haven't had any since," she said six months after the operation. Her phantom fist once felt crushed in a vice, but "now I have the freedom to open my hand. That's just made a world of difference."

Freedom from pain is surely a triumph in and of itself. But there's more. If you touch Loomis' inner bicep, where the hand nerves are now attached, she feels it in her "hand." Not only that, she feels it in specific fingers. When ice is applied to that same spot, her "hand" registers the cold.

If paired with a bionic arm—the most advanced of which are outfitted with sensors that register tactile information—she could, theoretically, not only maneuver it with her mind: She could also feel through it.

Just after the amputation, Dr. Seth promised Loomis he'd get her "as near a normal arm as there's ever been in the history of amputations." They saw just such an arm in Chicago, at a symposium on prosthetics. There they were introduced to an engineer from Johns Hopkins' Applied Physics Lab (APL). He was there to demonstrate the fruit of over 10 years of labor and $100 million: The Modular Prosthetic Limb. It's nothing like a normal arm, though. It's quite possibly the most advanced bionic arm in the world.

"When I saw, I'm like, that's it," said Dr. Seth. "That's the arm we need."

In 2006, DARPA launched the Revolutionizing Prosthetics program with the goal of designing a better prosthetic for amputee veterans returning from Afghanistan and Iraq. APL has long been a technical resource for the government. In fact, the lab was founded over 75 years ago for the purpose of developing technologies to assist the Allied effort in WWII, and continues to receive significant funding from the Department of Defense and NASA, among other agencies.

"DARPA came to us and said they need help in order to achieve this vision of having a human, via an interface with the brain, be able to control a humanoid prosthetic limb," said Mike McLoughlin, APL's Chief Engineer for Research and Exploratory Development. "At a time when people were saying it would take 20, 30 years to do this, they said we want to be able to do it in six."

It's a daunting undertaking. Until recently, the options for upper-limb prosthetics were woefully crude, essentially a hook that clasps open and shut—a design that predates the Civil War. Almost none of the technologies that would ultimately comprise the MPL were pre-existing.

But few labs are better equipped to tackle such a challenge. Under APL's umbrella are over 5,000 experts in an array of fields working on any number of wild projects, from space travel to biotechnology to "swarming" drones. The main floor of its Montpellier campus, which Motherboard visited this May, looks like the interior of a precocious child's imagination: work tables strewn with robot guts, circuits and Xbox controllers; Battlebot-like machines on caterpillar-track wheels, one of which—Robo Sally is its name—also had two MPLs that could maneuver and gesture with eerie dexterity. The whole effect of the lab would be menacing, a la Skynet, if it weren't for the palpable nerdiness and enthusiasm of its engineers. They're building the future. Clearly they enjoy their jobs.

Designing a neuro-interfacing bionic arm demands every bit of ingenuity and know-how they could collectively muster. "When you look at something like [the MPL]: it's mechanical engineering, it's electronics engineering, it's software systems, it's materials, it's neuroscience, it's biotechnology," says McLoughlin. "If you take any one of them away, it wouldn't have been successful."

There are 10 prototypes of the MPL currently. Each one costs about $400,000 to produce. Chief among their difficulties in bringing it to the consumer market is making it cheaper; as it stands, the MPL is not yet FDA approved, existing solely in research laboratories. But while other newfangled prosthetics—like the DEKA, also funded by DARPA—were designed to hit the market as soon as possible, APL's intention was different. They weren't just trying to make a better prosthetic. They were trying to make the most sophisticated bionic arm possible.

As such, the MPL was built with features—like 100 sensors measuring things like pressure and temperature—that the engineers at APL hoped would someday be useful for an amputee, once medicine caught up. So when they met Loomis and Dr. Seth at that symposium in Chicago, and heard about the TSR surgery, they were intrigued and excited. One of the difficulties with the bionic arm thus far is that if you're only sending information one way—from the nerves to the limb—you can't fully control it. If you grab a can of soda, for instance, you crush it because you don't know when to stop squeezing. If stuck in a dark room, you can't feel your way out. You need feedback.

The two parties exchanged information, and eventually agreed on a day for Loomis to come to APL and try out the arm. In one way, Loomis is a fitting participant in the Revolutionizing Prosthetics program: She comes from a long line of Marines, including her father, who accompanied her to Baltimore. During their trip, they had also arranged to visit Walter Reed, the military hospital. They wanted to speak to troops who are missing limbs, the very people the MPL was designed to help.

At APL, a dozen engineers and curious spectators gathered to see what the MPL is truly capable of. Loomis sat four feets from the most sophisticated bionic arm in the world, wearing on her bicep a set of electrodes that interpreted the neural sparks firing from her brain. Also on her bicep were another set of electrodes called "tactors," that passes the tactile information from the arm to her nervous system.

After calibrating the system, one of the engineers asked Loomis to think of raising her absent right arm. The MPL came to life, lifting upward. It wiggled its fingers when Loomis thought of it. It made a fist, a peace sign, a thumbs-up. And when she was asked to reach out and grab a ball, she did so with her eyes closed. She didn't squeeze it to death, either. A tingle in her "hand," a gentle jolt that felt like touching a battery, let her know she had it. An amazed hush overtook the room.

"I had this dream on December 10th, and it came to reality today," Dr. Seth told Motherboard later that afternoon. "Nobody can ever say that you cannot move or feel a prosthetic hand or arm again. We did it. You can tell every veteran that it's possible to feel something that is metal."

Loomis was surprisingly nonplussed. While everyone marveled at what felt like a breakthrough in medical science, she wore the slightest of smirks. "When I can pet a dog and feel fur, then we have hit the jackpot," she said later. "I'm going to be the bionic woman. I already have an insulin pump, and my husband always says, 'you're a cyborg, you have a robotic pancreas.' I'm already part robot. This is just the next step."

Made possible by Deus Ex: Mankind Divided. In stores August 23rd.

Tagged:
HUMANS
Tech
Motherboard
robotics
biohacking
prosthetics
motherboard show
DeusEx