prosthetic leg

Scientists have developed a breakthrough device that makes it possible for individuals amputated above the knee to feel a prosthetic leg. This innovative device results in greater stamina, stability, and mobility.

The researchers claim that sensors on a mechanical limb surgically connected to nerve endings in the thighs of volunteers reduced or in some cases removed the agonizing “phantom limb” pain that troubles so many amputees.

The study shows is a proof-of-concept study, which shows how beneficial it is to the health of leg amputees to have prosthetics that work with the neural implants. Stanisa Raspopvic is a professor at the Swiss Federal Institute of Technology in Zurich who led an international team of 20 researchers.
When an able-bodied person walks or runs, the nerves in the feet and legs send a range of electrical impulses to the brain with real-time data which helps determine the pathway like uneven roads, slippery floor, pebble-filled sidewalk, sloping surfaces, etc. This feedback allows the brain to make instant adjustments to catch, fall or change the amount of force needed.

But amputees do not benefit from this feedback, making it extremely difficult for them to walk steadily with confidence. They do not entirely trust their prosthetics. Therefore, they reply to their intact leg, which reduces mobility and causes them to get tired quickly.

To restore the flow of signals from limb to the brain, the researchers placed sensors under the soles of the prosthetic foot and around the joint of the electronic knee. Meanwhile, doctors surgically implanted electrodes into the volunteers’ thighs, connecting them with the same nerve endings that had once sent and received messages from the amputated lower limb.

Phantom pain

Once the sensors are connected by wires that pass through the skin, the electrodes partially restored the feedback loop. Even years after a limb has been removed, there is accumulated knowledge in the nerve fibers. These fibers are large in number and they elicit sensations through electrical stimulation.
To test the functioning of the new prosthetic, the researchers made the volunteers perform a series of tasks with and without the device. Without the neuro-feedback, the oxygen consumption of the volunteers was significantly higher along with a certain type of brain activity associated with concentration. The volunteers experienced a reduction in pain as well.

The researchers explained that the results were encouraging, but more tests and trials over a longer period and in-home use were needed before the technology could be bought into the market. The next step is to develop a fully implantable system accompanied by wireless neuro-stimulation, eliminating the need for wires to pass through the skin.


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