Researchers have worked with two patients with knee or transfemoral amputations. They used the Össur prosthetic leg, which comes with a microprocessor and an angular sensor in the knee joint, IEEE Spectrum explains. The team then added a seven-sensor insole to the foot. These sensors transmit real-time signals via Bluetooth to a controller pinned to the user's ankle. The algorithm in the controller encodes the feedback in the neural signals and delivers it to a small implant in the patient's tibial nerve, at the back of the thigh. The brain can then interpret these signals as feedback from the knee and foot.
The modified prosthesis helped users walk faster, feel more confident and consume less oxygen – an indication that it is less strained than a traditional prosthesis. The team is also testing the activation of the tibial nerve implant to ease the pain of phantom limbs. Both patients saw a significant reduction in pain after a few minutes of electrical stimulation, but had to be connected to a device in a lab to receive treatment. With more tests, researchers hope they can bring these technologies more amputated and make them both available outside the lab.