A new prosthetic leg that senses touch reduces phantom pain

Agility and confidence while walking increased in two men who tested the device

cycling with prosthetic leg

A prosthetic that senses foot pressure and knee angle may make all sorts of physical activity easier for an amputee, a new study suggests. 

Federica Barberi

A prosthetic leg that can feel helped two men walk faster, more smoothly and with greater confidence. The artificial leg, outfitted with sensors that detect pressure and motion, also curbed phantom pain that came from the men’s missing legs, researchers report online September 9 in Nature Medicine.  

Restoring these missing signals may greatly improve the lives of people who rely on prosthetic limbs (SN: 1/28/11). 

Neuroengineer Stanisa Raspopovic of EHT Zürich and colleagues tested the device in two men, both of whom had a leg amputated above the knee. Their new prosthetic legs were outfitted with seven sensors that detect foot pressure on the ground and one sensor that decodes the angles of the knee joint. Electrodes implanted on the sciatic nerve, just above the amputation site, then stimulated the nerve with signals from the sensors on the prosthesis. 

“If you close your eyes, you will think that you have your own leg,” volunteer Savo Panic said in Serbian in a translated video released by the researchers.

When those sensory signals were present, the two men walked faster and more confidently, even over difficult sandy terrain. What’s more, unpleasant feelings of pain from their missing leg lessened. After about a month of use, one of the men reported no pain at all, and the other man said his pain was sporadic.

As part of the study, the electrodes were removed after about three months. Longer trials with more people will let researchers fine-tune the device.  

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