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MIT-Developed Surgical Technique Makes Prosthetic Limbs Feel Real

Posted by Bryan Potok on

Proprioception—the body's ability to perceive its position in space—is vital because it allows us to control our body's movements precisely. However, during amputation, muscles are cut in a way that removes an individual's proprioception, which causes a sense of disembodiment and increases the rejection rate of prosthetic limbs.

 Surgical technique developed by MIT makes prosthetic limbs feel real.

To restore proprioception in amputees, researchers at the Center for Extreme Bionics at the MIT Media Lab have developed a new surgical technique that makes artificial limbs feel like biological limbs. This technique is also known as the agonist-antagonist myoneural interface (AMI), which preserves dynamic muscle relationships within the amputated limb.

The role of agonist-antagonist muscle pairs  

The reason amputees lose proprioception is they usually don't have agonist (contracting) and antagonist (relaxing or lengthening) muscle pairs, which are responsible for controlling limb movement. For example, when the biceps contract (agonist), the triceps relax (antagonist). Without these muscle pairs working together, it's difficult to sense where artificial limbs are placed or the amount of force being put on them. Without agonist-antagonist muscle pairs, it's difficult for an individual to manipulate objects or successfully balance.

MIT researchers recreated the agonist-antagonist muscle pairs through this new surgical technique, utilizing nerve signals undamaged after amputation. They connected the nerves to the muscle pairs, which were taken from other parts of the body into the residual limb.

The AMI allows patients to move prosthetic limbs by imagining moving their phantom limbs.

 

Image courtesy of MIT News

With this framework, patients don't have to think about controlling their prosthetic limbs; they simply need to imagine moving their phantom limbs, and signals will be sent via nerves to the surgically constructed muscle pairs. Implanted muscle electrodes will sense these signals. The brain is highly capable of remapping, it will quickly adapt to the new interface and interpret the force, muscle length, and speed based on the signals. The brain interprets this information as a natural proprioception.

First patient  

The AMI was first implemented surgically in a below-knee (BK) patient at Brigham and Women's Faulkner Hospital in Boston. Two AMIs were constructed in the residual limb at the time of initial amputation—one controls the prosthetic ankle joint, the other controls the prosthetic subtalar joint.

An advanced prosthetic limb was constructed at MIT, which was electrically linked to the patient's peripheral nervous system using electrodes placed over each AMI muscle after the amputation.

The researchers then compared the patient's movement with four participants who underwent a traditional BK amputation procedure and used the same advanced prosthetic leg.

The team found that the AMI patient had more stable control over the prosthetic device's movement and was able to move more efficiently than those with conventional amputation.

Furthermore, as the patients with traditional amputation reported feeling disconnected to their prostheses, the AMI patient described feeling the bionic ankle and foot had become part of their own body.

Since this initial procedure, the researchers have carried out AMI procedures on nine other BK amputees. Plans to adapt the technique for above-elbow, below-elbow, and above-knee amputations are currently in the works. 

What do you think of this development?  
Link to this page
<a href="https://amputeestore.com/en-de/blogs/amputee-life/mit-developed-surgical-technique-makes-prosthetic-limbs-feel-real">MIT-Developed Surgical Technique Makes Prosthetic Limbs Feel Real</a>

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11 comments


  • I am a bk amputee, how can I get it done

    Vance on

  • Hi, i am a bk amputee, 12 years ago, i had a nightmare elective amputation, 30 years after mining accident that crushed and nearly severed leg. It took several revisions to fix the shoddy job done by amputee doc. I have phantom and nerve pain on/off all day. Have Nevro pain stimulator, seems to help, cannot stand my prosthetics. I build my own. Have had 12 knee[both] surgeries, shoulder, two Ifuse si joint fusions, and probably 12 surgeries on the leg that was amputated. Any help or suggestions would be appreciated. I have always searched for a reduction in pain and increase in my standard of living. I am no victim, need straight talk, if you are up to it. Thanks mike

    Michael Stoll on

  • Fantastic,, if true. Anything that can connect the feelings and will reduce/eliminate phantom pain, wil be looked upon as miraculous. When i have such pain, thankfully rarelly, I am immobilized for a day or two.

    philip tamoush on

  • Can this work with an above knee patient? If so, I want to try!

    ERIC ROLLAND BARNES on

  • I am 62 year old women with two above the knee amputations. I had two knee replacements well it seemed like I was going every 8 months to a year to get a new knee replacement, I can’t keep doing that so I ask them to amputate them because I had a severe case of MRSA. They took all the metal out of my body. I was told I couldn’t get two prosthetic’s because of my age and it would be very, very hard for me to balance myself. So I would be willing to be a volunteer for y’all. Please text me back
    Thank you for your time, Sharon Smith

    Sharon Smith on


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