Dr. Gregory
Dumaniam, from Northwestern Memorial Hospital, presented his research on the
intuitive control of myoelectric prostheses using Targeted Muscle
Reinnervation. He studied how reconnecting nerves in the area proximal to
amputation can help an amputee to use their prosthetic limb to its fullest
extent and alleviate some of the stress associated with traditional prosthesis.
Dr. Dumaniam targeted four specific nerves in an attempt to regain complete
mobility and sensation in the prosthetic limb. The ultimate goal was to get
patients back to where they were in terms of mobility, sensation, and ability
prior to amputation of the limb.
With any
proximal amputation, the nerve remains intact with full functionality. This
sounds great, but can cause problems like phantom pain. Phantom pain is where
the nerve ending continues to send pain signals to the brain as if the limb was
still there. Dr. Dumaniam found a way to reconnect this nerve to restore
sensation and function, sometimes even relieving this phantom pain. The image
below diagrams the targeted muscle reinnervation surgery performed.
The major problem
with traditional prosthetics is that the amputee can only move one joint at a
time, and in order to do so the patient has to learn to use their muscle groups
in new ways because new muscles groups are now controlling these movements.
This can be very frustrating when learning to operate the prosthetic device for
the first time. Integrating Targeted Muscle Reinnervation (TMR) into prosthesis
is a step toward relieving this issue. TMR utilizes this nerve signal and
innervated muscles to allow the amputee to operate the prosthetic limb. For
example, with an arm amputation, the remaining nerve can be connected to the
pectoral muscle in order to operate a prosthetic arm. To activate the muscle
and move the prosthetic, the brain sends the same signals as if the original
muscle was still attached, then this signal innervates the new muscle (pectoral
muscle) and this muscle operates the prosthetic.
New technology
such as TMR that has been implemented in the field of prosthetics has had a
huge impact on soldiers who have lost limbs fighting overseas. Losing a limb
used to mean the end of active duty for a member of the armed forces, which can
be absolutely devastating for someone who has chosen to dedicate their life to
serving their country. The increasing number of injuries overseas has required
advancements in the way of prosthetic technology and rehabilitation for
soldiers. Some soldiers were even able to return to active duty following
mastery of their new prosthetic. At least 167 soldiers with major limb
amputation have remained on active duty since the start of the Afghanistan and
Iraq wars, with some even returning to battle.
With improved
functionality, the amputee no longer has to worry about or focus on
manipulating the prosthetic device, and can focus on the task at hand. Kevin
Carroll, Vice President of Hangry (a prosthetics company), said "if they
want to go back to be with their troops, that's an option these days." In
many cases it takes at least a year before a soldier is able to return to duty,
and each branch of the military has its own guidelines for this. However, once
they are able to return to duty, soldiers who are going back into battle are
able to perform just as well (at the same physical level) as their fellow
soldiers if not better. Even with all these advancements, though, America still
won't be training an army of bionic super-soldiers any time soon. Who knows
though, maybe one day it will be possible. For now, we'll settle for increased
sensation and functionality.
Resources:
https://www.usnews.com/news/articles/2012/05/25/new-prosthetics-keep-amputee-soldiers-on-active-duty
http://usoonpatrol.org/assets/mc/ebrandner/2012_01/Spanky3_web.jpg
http://files.greatermedia.com/uploads/sites/80/2017/04/Flickr_-_The_U.S._Army_-_Departure_Ceremony-e1420556275773-1024x735.jpg
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