It’s based on a method known as agonist-antagonist myoneural interface (AMI), which was invented at MIT. The idea behind the procedure is to replicate muscle pairings that come second nature to us, like when we move our foot from side to side.
Jim Ewing was the first patient to undergo the procedure in 2016, after falling 40 feet on a rock climbing trip. This below-knee amputation reconnects the muscles and nerves that communicate with the brain. The surgery took place at Brigham and Women’s Hospital, home of the Stepping Strong Trauma Innovation Center, which provided seed money to research this procedure.
Reconstructive plastic surgeon Matthew Carty, who performed the operation, said it’s a major advancement compared to a standard amputation, which severs connections between the muscles and the brain.
“When a patient with a standard amputation thinks about moving their ankle, which is no longer there, for example, they only get half the information. And so, the brain searches for a way to process that incomplete equation," Carty said.
The Ewing amputation closes the loop, making the brain think the limb is still there because the nerves and muscles are still intact.
“And the idea is that once they've healed, when they fire off those muscles and think about moving their ankle, their body basically thinks it's moving a biological ankle still,” Carty said.
Only it’s not a biological ankle, but a robotic one. Carty is working with the Biomechatronics Group at the MIT Media Lab, where researchers are developing what is essentially a bionic leg.
Stickney, who underwent her first Ewing amputation in May 2018, is among the first to test it out. Inside the Media Lab, Ewing amputees like Stickney can move a robotic ankle just by thinking about it. With the use of sensors on the muscles, a small computer decodes the sensors. The signals can then be used to directly control a motor in a bionic limb. It's a potential game-changer for anyone who uses a prosthetic leg.
Hugh Herr, a double amputee who directs the Biomechatronics Group, said his lab is now focusing more closely on sensing touch.
“The brain gets information about how muscles are moving, but the brain doesn’t get information about skin contact,” Herr said. “So what we are doing now, is we are putting skin cells next to the nerve. The nerve grows again and attaches to the skin cells. We then wrap a muscle around the skin cells. Using the computer, we electrically stimulate the muscles to squeeze the skin cells.”
Months after her first amputation in 2018, Stickney won two national championships and was living in Colorado, training for the 2020 Tokyo Paralympics. Then, in January of this year, the unthinkable happened.
“I was recovering in the cold tub and I got out and hopped three steps, and my foot fractured,” she recalled.
She had a bone infection in her right foot. This time, after seeing more than 20 doctors, she got a diagnosis: an extremely rare vascular disease where there was very little blood flow in her lower limbs, resulting in brittle bones. It explained all those years of pain.
“I think a lot of people, when they find out they had a disease, they would be bummed, but for my family and for Dr. Carty, it was an exciting thing to know that I finally had a diagnosis and to know that there was actually something physically there. It wasn't just, ‘Oh, Morgan's in pain and these bones are randomly dying.’ It was like, no, there's actually a disease that's causing this condition,” Stickney said.
It also meant having her right leg amputated. Last month, Stickney became the first person to undergo a bilateral Ewing amputation.
Weeks after her second leg amputation, at a recent session inside Spaulding Rehabilitation Hospital in Boston, Stickney, with her optimism and matter-of-fact attitude, explained that she has come to approach physical therapy like a personal training session.
“I like to treat PT [physical therapy] and OT [occupational therapy] like a workout. If I can’t be in the pool, I can be in the gym,” Stickney said, smiling broadly.
“I mean, the night before, don't get me wrong, I was sobbing and asking, ‘Why me? Why me?’ But, you know, at the end of the day, I can walk,” she said.
It will be at least five years until these bionic limbs are commercially available, but for Stickney, the immediate payoff of the Ewing amputation was being pain-free and returning to competitive swimming.
Stickney stays in close touch with the eponymous Jim Ewing. She refers to him as “Amp Dad.” He said learning of her diagnosis was a relief, but it came with profound disappointment.
"Once you make the decision to amputate, it seems like, you wait for it to happen, but it is a wild, emotional roller coaster because you go through this whole grief process time and time again," Ewing said. "You want to do anything to keep your foot, so you really wrestle with your conscience. It’s really scary because you can’t put it back on."
Carty, the reconstructive plastic surgeon at Brigham and Women’s Hospital, said it takes an adventurous person who is also skeptical but willing to do the hard work required in recovery to undergo the Ewing amputation. Ewing, who said using his own last name to describe the amputation is “a little creepy,” can attest to that.
“I once commented to Dr. Carty about how certain [Ewing amputee] individuals are pretty intense, and he said, 'Actually, I think you’re all pretty intense,'" Ewing said.
Brigham and Women’s Hospital has received three grants from the Department of Defense to continue and expand its research of the Ewing amputation. The hospital told WGBH News it will start offering the Ewing procedure for those in need of upper limb amputations. While the funding covers some of the costs, patients like Stickney often face mounting medical costs. She has a GoFundMe page in an effort to relieve some of the financial burden.
In the meantime, though, she’s already thinking about getting back into the pool.
“Nothing will stop me from getting in the pool,” Stickney said. “My goal is to go to the 2024 Paralympic Games. I'll be in a different classification this time, but that doesn't change anything. Whether I'm going to be working just as hard in the pool, if not harder.”