Paris (AFP)
An innovative prosthesis unveiled Monday has restored the sensations of walking in two patients yet amputated a leg, opening important opportunities to improve the mobility of prosthetic wearers and reduce pain "ghost member".
A team of Swiss researchers has developed a prosthesis with sensors at the level of the sole of the foot and the fold of the knee, connected to electrodes implanted directly on the nerves of the leg.
This system allowed the two patients, amputated above the knee, to recreate the sensitivity of the lost limb, allowing them for example to differentiate between walking on the road or in sand.
"The use of this prosthesis has improved the quality of their walking and increased their endurance, both in the laboratory and in a real environment," reports the article published in the journal Nature Medicine.
Moreover, she reduced their "phantom limb pain". These pains, felt as though they were from an amputated limb, occur when the neurons in the amputation area continue to send messages of pain to the brain.
As a field in full development, prostheses in direct interaction with the nervous system - "direct neural interfaces" or "brain-machine interfaces" - improve the quality of life of paralyzed or amputated patients, by allowing them to "control" the movements of their artificial limb.
But a major obstacle to their adoption remains the lack of "sensation" from the prosthesis, essential for fine motor skills and interactions with the outside world.
An Austrian team had achieved a similar result in 2015 for a sub-knee amputee, and experiments were also conducted on the upper limbs.
But this is the first time that such a prosthesis is placed on a lower limb amputated above the knee, told AFP Stanisa Raspopovic, a professor at ETH Zurich University (Switzerland), who points out that the nerves of the lower limbs are "much bigger" and more complex than those of the arms.
After this first two-person trial, Pr Raspopovic's team launched a four-year clinical trial to implant the prosthesis to "a significant number of patients" and follow them over a longer period.
© 2019 AFP