People who have lost forearms and elbows tend to have more difficulty controlling movable prostheses. In such cases, there are typically only limited muscle strands available to control an artificial arm or an artificial hand with fine motor control. However, a research team promises to have found a groundbreaking solution to this problem.
The recently published study presents the first documented case of a person whose body was surgically modified to accommodate implanted sensors and a skeletal implant. AI algorithms were eventually used to translate the subject’s intentions into movements of the prosthesis. These surgical and technical advances may allow more people to move the fingers of their bionic hand as if they were their own.
Too few remaining muscles make movement difficult
Although prostheses are considered a huge scientific advance, they also often present challenges, especially when only a few movements are possible. In cases where residual muscles are present in the remaining body part, they are a preferred source of control for bionic hands. This is because patients can selectively tense existing muscles and the electrical activity generated can be used to tell the prosthetic hand what action to perform, such as opening or closing the hand.
However, a higher level of amputation, for example above the elbow, poses a major problem as there are too few muscles to control bionic arms and hands.
Rewiring of nerves for better control
A team of researchers, led by bionicist Max Ortiz Catalan from Chalmers University of Technology in Sweden, now promises to have found a solution. The article in the journal Science Translational Medicine illustrates this first documented case of the successful connection between man and machine.
To compensate for the missing muscle strands that are necessary for precise control, the researchers proceeded as follows: First, they removed the compressed nerve tissue that resulted from the amputation. The remaining nerve cords were then divided into several nerve bundles called fascicles. Certain fascicles were then relocated to the remaining muscles in the stump. These muscles, which were then supplied with electrical impulses again, were then equipped with special electrodes that were implanted either in the connective tissue or directly in the muscle. This ultimately made it possible to receive electrical signals and control the prosthesis.
In this video, the researchers want to show how the system reacts to everyday activities:
The special feature of this solution, which has already been tested with test persons, is that it should be possible to use individual fingers in an intuitive manner. This means that the affected person only has to imagine the movement and the prosthesis reacts accordingly.
New hopes and possibilities
“It is rewarding to see that our cutting-edge surgical and technical innovations can offer such a high level of functionality to a person with an arm amputation. This success is based on more than 30 years of gradual development of the concept, to which I am proud to have contributed,” says Dr. Rickard Brånemark, research associate at MIT who performed the implantation of the interface.
With implanted sensors and the skeletal implant both being seamlessly connected to the body and using AI algorithms to translate the user’s intentions into movements of the prosthesis, new hopes and possibilities are opening up for people with arm amputations worldwide. The researchers are currently in the process of further improving the controllability of the bionic hand.
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