Tuesday, February 13, 2018

An Arm and a Leg: The Advent of TMR Prosthesis

According to a study done by Access prosthetics, there are over 2.1 million people living with limb loss in the United States alone. This number is projected to double by 2050, which is a staggering amount. Even more surprising, there are about 185,000 amputations each year, which equates to about 300 to 500 amputations every single day. Prosthetic limbs have become an integral part in the rehabilitation of those who suffer from limb loss. Because of its importance, finding a prosthetic that is more humanized and less robotic has taken the center stage in the development of future prosthesis. Dr. Kuiken’s research on developing a better prosthetic experience using targeted muscle reinnervation (TMR) serves to model the future of prosthetics.
Dr. Kuiken’s lab focuses on expanding the building blocks that have been laid down for developing prosthetics for patients with amputations. Prosthetics, according to Dr. Kuiken in his presentation, are not very intuitive, clunky, and take a long time to learn. His lab focused on developing a prosthetic that used targeted reinnervation of chest nerves to do specific commands in the hand and arm, such as moving fingers and wrists. The first patient was a 54 year old line man who had damage from an electric accident at work. Dr. Kuiken worked with his team to inserting electrodes with 4 different signals in the chest that used nerves that had once been connected to the missing limb. Because the nerves had been previously used for the arm, but were now defunct due to the amputation, Dr. Kuiken was able to successfully reinnervate them to function in using the prosthesis. 94% of the nerve transfers were successful in producing usuable EMGS. His use of TMR showed an increase in ability of using the hand.
Dr. Kuiken’s initial goal was to implant nerve transfers of the median and ulnar nerves to get info for controlling the dexterous hand. However, in doing these procedures, his labs found that a person could actually feel sensation in the chest from the prosthesis. The person could feel differentiations between sharp and dull stimuli, while also telling the difference between temperature changes.
Another hypothesis that I found very interesting within Dr. Kuiken’s presentation and research papers was the study of Neuroma for pain. According to an article by the Amputee Coalition, a neuroma is “a collection, or bundle, of nerve endings that forms under the skin of your residual limb”. These nerve bundles can become very sensitive, especially when pressing against an amputee’s prosthesis. Dr. Kuiken hypothesized that amputee’s experience pain because there is nothing to innervate, and the brain equates this to sending pain signals. Because regular prosthesis don’t focus on innervation, and thus there is no new formation of connection to the brain. However, with TMR prosthesis, there was an overall decrease in pain from neuromas after surgery was performed. Dr. Kuiken hypothesis is supported because after the nerves for hand and arm movement were reinnervated, pain decreased.
While Dr. Kuiken’s research is certainly groundbreaking, the biggest implementation for improving the care of amputees does not fall into a scientific category. According to an article by ABCnews, the price of a prosthetic limb can cost anywhere from “$5,000-$50,0000”.  It is also important to note that prosthetics are only able to last around 3-5 years, meaning that a person must constantly replace their prosthesis. Other costs including physical therapy to learn how to use the prosthesis drive the price up even further. This notion of expensive healthcare has is telling of the stigmatization of healthcare in the U.S., which has historically been grossly expensive.
Dr. Kuiken’s work serves to be revolutionary in the care of amputee patients. The ability for a person to use their brain to control prosthetics in an intuitive way is beneficial not only to a person’s physical abilities, but also their mental health. Losing a limb can be a very traumatic experience, and thus providing a way for a person to feel like they have control of their limbs could be very beneficial. The United States must also focus on working on lowering the cost of prosthetics, so that more people could benefit from having prosthetics, and improving their lives in the face of what can be considered a true tragedy.
References:
15 Limb Loss Statistics that May Surprise You. (2017, October 18). Retrieved February 8, 2018, from https://accessprosthetics.com/15-limb-loss-statistics-may-surprise/
Management of Residual Limb Pain. (n.d.). Retrieved February 8, 2018, from https://www.amputee-coalition.org/limb-loss-resource-center/resources-for-pain-management/management-of-residual-limb-pain/
Mohney, G. (2013, April 25). Health Care Costs for Boston Marathon Amputees Add Up Over Time. Retrieved February 08, 2018, from http://abcnews.go.com/Health/health-care-costs-boston-marathon-amputees-add-time/story?id=19035114


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