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A groundbreaking surgical procedure gives amputees bionic limbs that are controlled directly by the nervous system, allowing patients to sense the position of the limb in space.
Scientists have demonstrated the success of this technique in a new study of seven people who were given bionic legs, published Monday (July 1) in the journal NaturopathyIncluding these seven, approximately 60 people worldwide have undergone this procedure, which can implant both bionic legs and arms.
“This is the first prosthetic study in history to demonstrate a prosthetic leg under full neural modulation, producing a biomimetic walking motion,” Hugh Herrco-author of the study and professor of media arts and sciences at MIT, said in a rackIn other words, the synthetic prosthesis can fill the lost function of the missing limb, thus creating a natural gait pattern.
“No one has yet been able to demonstrate such a level of brain control that produces a natural gait, where the human nervous system controls the movement, not a robotic control algorithm,” Herr said.
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The operation itself, known as agonist-antagonist myoneural interface AMI involves reconnecting the muscles in a patient’s stump after a below-the-knee amputation, in the event the patient receives a bionic leg.
Electrical signals from the central nervous systemthat transmit instructions for movement can then pass between these muscles and be detected by electrodes in a newly installed prosthesis. The signals are picked up by a robotic controller in the prosthesis, which allows it to control a patient’s gait or walking style. Signals about the position and movement of a patient’s prosthesis are then fed back to the nervous system.
In a series of experiments described in the new paper, the seven patients who underwent AMI surgery were able to walk faster than people who received the same type of prosthesis but who had traditional amputations. Some patients were even able to walk as fast as people without amputations. They were also able to avoid obstacles and climb stairs more naturally than patients who had traditional amputations.
Current prosthetic technology already allows amputees to achieve a natural walking gait, according to the team that performed the surgery. However, these prosthetics rely on robotic sensors and controllers to actually move in a predefined, algorithmic pattern, the team said. AMI, on the other hand, allows the limb to respond dynamically to signals from the body.
“Our approach aims to connect the human brain with electromechanics in a comprehensive way,” says Herr.
The patients who underwent AMI also had less pain and muscle atrophy, the scientists reported.
AMI can also be used in people who have had an arm amputation, the team said. The surgery can be performed at the time of the patient’s original amputation or at a later date.
“This work is another step in demonstrating what is possible in terms of restoring function in patients suffering from severe limb injuries,” Dr. Matthew Cartyco-senior author of the study and associate professor of surgery at Harvard Medical School, the statement said.
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