Electromyography Is Feasible for Controlling Future Bionic Legs

Researchers at Rehabilitation Institute of Chicago (RIC) have shown that leg amputees posses enough neural signal to control the ankle and knee joints in a potential bionic leg that would detect electrical activity in remaining muscles. Before building a real prosthesis, the investigators used electromyography (EMG) on four amputees to control a virtual leg on a computer. The results, published in the latest JAMA, showed great promise for EMG in lower leg prostheses.

Dr. Hargrove’s research published in JAMA investigates real-time neural control in four lower limb amputees and four non-amputee control participants, measuring the EMG signals in nine lower limb muscle sites during lower limb movement. Through real-time tests, all participants were instructed to move a virtual lower limb through a variety of motion patterns on a computer screen. Metrics were based on accuracy of movement, the time it took to complete the motion and the percentage of successfully completed motions.Results from the trial showed all participants were able to control their knee and ankle from neural information measured in the thigh. The average motion completion rate for knee and ankle movements (knee flexion/extension and ankle dorsi-flexion/plantar flexion) was high at 97.2 percent for amputee patients and 95.1 percent for control participants. The average motion completion times for knee and ankle movements were 2.53 seconds for amputee patients and 1.94 seconds for control participants. The average accuracy of movement rates were 91 percent for amputee patients and 89 percent for control participants.

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Abstract in JAMA: Real-Time Myoelectric Control of Knee and Ankle Motions for Transfemoral Amputees