The Ewing Amputation
Background, History, and Outlook
The Ewing amputation is being developed to address the need for two-way communication between the residual limb and prosthesis in patients with lower-limb loss. When patients are able to walk in traditional prostheses, they experience a lack of proprioception, the ability to sense your limb’s position, force, and speed of movement.
During amputation, nerves are severed and damaged. The brain loses signal from the missing arm or leg. The brain attempts to rewire, and mismatched signals between the brain and the residual limb ensue. These are thought to cause these relentless, often brutal sensations of phantom limb pain as well as proprioception loss. Phantom limb pain affects 80% of patients and is defined by debilitating pain felt in the part of the limb that no longer exists. The Ewing amputation aims to prevent this by allowing two-way communication between the brain and the residual limb.
MIT professor Hugh Herr and reconstructive plastic surgeon Matthew Carty pioneered the Ewing amputation. Instead of cutting feedback between the limb and the brain, the procedure creates a “tendon pulley system” to preserve the limb muscles’ natural dynamic (stretching and contracting of muscles). The goal is for the patient to feel more connected to the prosthetic limb and to have more control over it. Recipients of this procedure have experienced this and more – including substantially reduced phantom limb pain and greater proprioception.
A prodigy rock climber, Herr lost both of his legs after ascending a difficult ice route on Huntington Ravine and getting caught in a blizzard. Since then, Herr has become a noteworthy engineer and biophysicist with over 120 peer-reviewed papers in the field of rehabilitation science and 100 patents related to assistive devices under his belt. He is currently a professor at the MIT Media Lab, director of the Biomechatronics research group, and co-director of the MIT Center for Extreme Bionics.
Carty is the director of the Lower Extremity Transplant Program at Brigham and Women’s Hospital and a professor at Harvard Medical School. He works with the Biomechatronics group at the MIT media lab, where Herr and researchers are developing the device for this surgery. Carty leads the clinical teams involved in this surgery and has performed 9 Ewing amputations to date, all below the knee.
Currently, the procedure is performed by a small subset of clinicians in patients requiring below-the-knee amputation. It cannot be performed after amputation (e.g., in emergency settings). The foot-ankle technology associated with the procedure is costly.
The outlook is hopeful. The surgery is expanding to above-the-knee patients with the first surgeries having already taken place. It will likely be adapted to upper limb amputations in the future according to Next Steps Bionics & Prosthetics, who has fitted eight Ewing patients to date. Finally, it is Herr's intent to make this surgery more accessible to all who may benefit from it. One goal is to reduce costs by increasing philanthropic funding and scaling the technology.
About Writer: Pranita Muralidhar
Pranita is passionate about health sciences, entrepreneurship, and connecting people with products that benefit them the most. By contributing to the blog, Pranita hopes to help raise broad exposure and awareness of TheraV ELIX.
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