Why you should care
Because old-school surgical amputation hasn’t kept up with modern-day medicine.
Jim Ewing, a 55-year-old engineer from New Hampshire, suffered a traumatic rock climbing accident in late 2014. While most of Ewing’s broken bones healed over time, the talus in his left ankle gnawed at him mercilessly. “I started thinking that amputation might be my best option because there was so much damage in my foot,” Ewing says. Desperate for relief, he called his former roommate, Hugh Herr. As it happens, Herr, a bilateral below-knee amputee himself, is head of the biomechatronics group at the MIT Media Lab and a world leader in prosthesis research.
Ewing’s friend told him about a new procedure that would deliver not only a successful amputation but also a prosthesis that he could control with his brain. That new system is the brainchild of Tyler Clites, the 28-year-old who won the prestigious Lemelson-MIT Student Prize in 2018.
Clites’ goal is nothing short of audacious: He wants to build bionic prostheses and create a neural interface between robot and human so the two can work together. To do so will require an entirely new approach to surgical amputation, the first of its kind to target proprioception — a fancy word for our ability to sense where our bodies are in space. While traditional amputation disrupts proprioception, Clites’ approach preserves it.
Clites, a postdoctoral fellow at the University of Michigan, has devised a two-pronged strategy: First, preserve the muscles’ relationships with each other through biological tissue that acts as pulleys so that when one muscle contracts, the interconnected one stretches. Second, introduce a robotic system that measures the electrical activity in the targeted muscles and uses the data to interpret the wearer’s intention.
Assuming all goes according to plan, when a person whose foot has been amputated, for example, tries to point the toes on the prosthetic device, the control system would pick up the associated electrical activity from her muscles and direct the toes to point in the intended direction and, equally important, with the correct degree of force. In essence, the wearer controls how the device moves with her mind, and the neural interface allows her to feel the prosthetic foot moving as if it were part of her own biological leg.
When Ewing heard about this novel technique, he got fully on board. Any reservations he had were nothing compared to the decision to remove a limb. “I figured the worst-case scenario is that I would end up with a standard amputation if the interface hadn’t worked as predicted,” he says.
In July 2016, the operation was performed by Dr. Matthew Carty, Clites’ mentor and collaborator at Brigham and Women’s Hospital in Boston. Ewing was rock-climbing again in under a month. Since then, 13 more patients have successfully undergone the surgery, a remarkably fast pace for a brand-new experimental procedure being scrutinized in an early validation phase. Since the operation does not involve implanted devices, Food and Drug Administration approval is not required, although the procedure did have to pass muster with an institutional review board. At present only Carty is performing the surgery, but it’s expected that the current clinical trial will bring the total number of patients to 20 by 2021 and provide enough data to motivate clinical adoption at a broader scale.
Dr. Paulinder Rai, medical director of the amputee program at Lynbrook Restorative Therapy and Nursing, and a wound care physician at Mercy Medical Center’s Center for Hyperbaric Medicine and Wound Healing in Rockville Centre, New York, says that Clites is looking to solve “quite possibly the biggest problem in the world of prosthetics.” That said, Rai worries about whether the procedure will translate as effectively to upper-extremity amputations where there’s significantly more intricate coordination of muscle movements at play.
Clites agrees that the upper extremities present a new challenge, but he’s working toward it. “Our arms are weaker, but there’s a lot more dexterity, so surgically there’s complexity in the upper extremities that we will have to see how it plays out,” he says.
What’s the point of marshaling our design efforts to build awesome robots that we slap on the body without changing it?
Given Clites’ grand ambitions, it’s ironic that he stumbled into the field almost by accident. Growing up in Dunbarton, New Hampshire — his mother was an elementary school teacher and his father owned a landscaping business — he liked science and invented a prototype egg cracker one summer at Camp Invention. But when he got to Harvard, he wasn’t sure what he wanted to study. A service trip to Brazil after freshman year — Clites is a member of the Church of Jesus Christ of Latter-day Saints — was the eye-opener he’d been looking for. “I saw firsthand the impact that limitations in mobility and locomotion can have on a person’s life, especially in an underserved area,” he says. Clites had been chatting with a colleague about prosthetics research before leaving for Brazil, and the trip cemented his goals: Once he returned to the States, he got involved with Hugh Herr’s lab and eventually completed his Ph.D. in biomedical engineering through a joint program between MIT and Harvard Medical School.
As his work pulls him deeper into New Age bionics, Clites argues that society will need to wrestle with larger questions about what the human body may look like in the near future — pointing out that people are comfortable with the idea of rehabilitation when it comes to limbs, but not augmentation. What if we were to become faster runners with these procedures, would that be OK? Might healthy (and wealthy) people elect to have the surgical interface? “The primary concern will be access and the possibility of further stratifying the socioeconomic divide, but as the market size for this type of technology increases, the cost should go down,” Clites says.
The ethical debate will take time, but for now, Clites is unwilling to accept the body with its limitations and shortcomings. What, he asks, is the point of marshaling our design efforts to build awesome robots that we slap on the body without changing it? Far more remarkable, he says, would be to engineer the body in parallel with the machine so the two are optimized to interact with each other — to create a better cyborg, in other words. Audacious? Definitely. But not out of the question.
OZY’s 5 Questions With Tyler Clites
- If you went back to Camp Invention, what would you invent today? As an academic, every day of my life is Camp Invention. I spend that time creating technologies to improve human movement and locomotive ability, with the goal of helping people interact more fully with the world around them.
- Do you like watching medical dramas? Any favorites? I have been known to watch a few. I’m quite partial to the early seasons of Scrubs, which I think captures life in the clinic well.
- What’s your favorite cyborg movie? The scene that played a role in starting me down my career path was the rebuilding of Luke’s arm in Star Wars Episode V: The Empire Strikes Back. I find remarkable the idea that a synthetic limb could become so integrated with Luke’s sense of self that it more or less disappeared from the storyline.
- What’s one item on your bucket list? Innovate a medical technology that truly transforms clinical care for a group of patients.
- What’s your idea of a dream vacation? Wildlife tour of the Galapagos Islands.
Learn more: OZY’s Future of X podcast delves into prosthesis in the Future of Doctors: Digital Tattoos episode.