A robotic control system for a prosthetic leg allowed a 31-year-old man to walk and climb stairs with a nearly normal gait. The system links nerves in the thigh — including some for missing muscles in the lower limb — to a processor that decodes the signals and guides the motion of the prosthesis, according to Levi Hargrove of the Rehabilitation Institute of Chicago.
The prosthetic limb includes thirteen mechanical sensors and can be used — like many commercially available prostheses — by changing its settings with a wireless key fob. Combining electromyographic signals from the residual limb and the sensor data eliminated the need to change settings with an external device and produced unique stride patterns for each type of ambulation, such as walking on a ramp and climbing stairs. Adding the data from the nerves to the information from the sensors reduced the error rate — misclassification by the control system of the patient’s intended movement — from 12.9% to 1.8% of all motions.