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An international team of researchers, led by the Federal Polytechnic School of Zurich (ETH Zurich), in Switzerland, and the new company with headquarters in Lausanne Sen-sArs has developed an interface to connect a prosthetic leg with nerve waste present in the thigh of the user, thus providing sensory feedback that allows management more natural of the same, according to published in the latest issue of the journal ‘Nature Medicine’.
in a study conducted In collaboration with the University of Belgrade, the scientists tested this system neurofeedback with two volunteers who have an amputation leg above the knee and wear a prosthetic leg .
When walking, people with their legs intact feel when you move your knee or when the feet touch the ground. The nervous system uses constantly to the sensory feedback of this type for accurately controlling the muscles. However, people who use a prosthesis, you do not have the same perception so that often can not rely entirely on their prosthesis when they walk, which leads them to rely too often of his leg intact, which in turn reduces your mobility and makes you tired quickly.
surgeons placed small electrodes in the thigh of each volunteer and were connected to the nerves of the residual of the legs.
A simple walk on stones or sand, for example, can be very strenuous for people who use a prosthesis. Furthermore, the amputees may experience phantom limb pain, a condition that the existing drugs are often not able to treat.
This new find has benefited amputees in several ways. “This proof of concept study shows how beneficial it is for the health of the amputees of the legs to have a prosthesis that works with neural implants to restore the sensory feedback ,” says Stanisa Raspopovic, a professor in the Institute of Robotics and Intelligent Systems at ETH Zurich.
in order To provide sensory information to the nervous system, the scientists began with a high-tech prosthesis that is commercially available. Connected touch sensors in the sole of the prosthetic foot and collected data on the movement of the knee provided p or the joint electronics of the prosthesis.
During the three-month period of the experiment, the surgeons placed small electrodes in the thigh of each volunteer and were connected to the nerves of the residual of the legs.
“The goal of the surgery was to introduce electrodes in the correct locations within the nerve to allow the restoration of the sensory feedback in real and allow the stability of the electrodes” , explains Marko Bumbasirevic, professor and microcirujano orthopedic in the clinical Center of Serbia, Belgrade , who was responsible for the implant of electrodes. The electrodes were developed by scientists from the University of Freiburg, and the prosthesis is of the company of prosthesis Ossur.
nerve signals residual are transmitted to the brain of the person, which can detect the prosthesis and helps the user to adjust their gait to agree with it. The machine and the body are finally connected.
The research team developed algorithms to translate the information of the tactile sensors, and motion into current impulses, the language of the nervous system, which were united to the nerve residual. Then, nature does the rest: the signals of the nerves residual are transmitted to the brain of the person, which can detect the prosthesis and helps the user to adjust their gait to agree with it. The machine and the body are finally connected.
As part of the study, the volunteers underwent a series of trials, alternating trials with and without neurofeedback. The results made it very clear how advantageous that was the feedback: walk with neurofeedback was physically much less demanding , as evidenced by the significant reduction in the consumption of oxygen of the volunteers while they are walking.
Also mentally, ambulation with neurofeedback was less strenuous, as demonstrated by the researchers with measurements of brain activity during the tests. The volunteers did not have to concentrate as much on his walk, which meant that they could devote more attention to other tasks.
ambulation with neurofeedback was less strenuous, as demonstrated by the researchers with measurements of brain activity during the tests
The interface with the nervous system can also be used to stimulate the nerves independently of the prosthesis. Before starting the test, both volunteers complained of pain in the phantom limb.
In the course of a therapy program of a month with neurostimulation , the scientists were able to significantly reduce this pain in one of the volunteers; In the other the pain disappeared completely. “Since I began this treatment program, after having received electrical stimulations, I don’t feel any phantom pain,” he says.
The scientists see these results so optimistic. However, they point out the need for further research long assessments in the home and a greater number of volunteers , in order to provide stronger data that can be used to draw conclusions more significant.
