For athletes, physical agility, strength, and flexibility are of paramount importance. Standard prosthetics, which can severely limit athletic performance in the aftermath of amputations, can be underwhelming for these patients. That was the experience of Hugh Herr, PhD, now Director of the Biomechatronics Group at the MIT Media Lab. After a rock climbing injury as a teen left him a double amputee, he was unimpressed with the prosthetic limbs available, and committed to finding new solutions—eventually connecting with Matthew J. Carty, MD, a plastic surgeon at Brigham and Women’s Hospital (BWH).
Dr. Carty envisioned a leg transplant surgery that maintains essential nerve connections between the new leg and brain. “During a standard amputation procedure, the nerve signals that coordinate between the brain and limb are cut off, making it nearly impossible for an amputee using a prosthesis to walk on uneven ground or balance on one leg,” explains Carty, director of the Lower Extremity Transplant Program at BWH and Brigham and Women’s Faulkner Hospital.
When Herr and Carty learned of each other’s efforts, their brainstorming led to a new idea: an amputation surgery that spares essential nerve connections between the new leg and the brain, and a brain-controllable prosthesis. After several years of significant pre-clinical research at MIT and the New England Organ Bank, in July 2016 the team piloted the new amputation procedure in Herr’s longtime friend Jim Ewing, who had suffered chronic pain following a rock climbing injury. The experimental amputation-as-treatment procedure, funded through The Gillian Reny Stepping Strong Center for Trauma Innovation at BWH, had Ewing walking with a standard prosthesis and rock climbing again. The Herr-Carty team then took Ewing’s progress to the next level with the robotic prosthesis they’d spent years co-developing. The prosthetic limb was designed to connect to Ewing’s muscles so he could control its movements with his brain and feel sensations similar to a natural limb.
Ewing says, “Within minutes of being connected to the robotic prosthesis, I felt like it was part of my body, what Dr. Herr and Dr. Carty call neurological embodiment. The sensation of a robotic foot responding to what I am thinking and doing is incredible.”
The amputation procedure, now known as the Ewing Amputation, and the robotic prosthesis developed by Dr. Carty and Dr. Herr stand as evidence of what’s possible when bioengineers, physicians, surgeons, and scientists build clinical collaborations with a commitment to innovation. While more testing is needed, Carty and Herr expect a version of the prosthesis will be publicly available within a few years—helping to redefine the care of amputees and improve quality of life for the nearly 1 million people worldwide who have limb amputations each year.
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Photo credit: Stu Rosner (via Brigham Health Magazine)