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INNOVATION FOR INDEPENDENCE
ISSUE 79 June/July 11 £6.95
Aneural control of bionic leg moves closer
By Dominic Musgrave ANEURAL control of a bionic leg by amputees has moved a step closer after a preliminary study revealed promising results. Four patients with above-the-knee amputations were able to perform various leg and foot movements in a virtual environment using signals from the muscles of their upper legs, claims Levi Hargrove, of the Rehabilitation Institute of Chicago, and colleagues. The three men and one woman, with an average time since amputation of 18 years (range of about five to 20), all had electrodes placed on the skin's surface over nine muscles in the upper leg. Levi said their performance was roughly comparable to that of four participants who had intact limbs. He added: “We were expecting to be able to control knee movements. We were not expecting to be able to control ankle movements. “Our preliminary results demonstrate successful neural control of both the ankle and knee joints and represent a significant step in our efforts to develop a neuralcontrolled prosthetic leg for the millions of
people living with lower limb loss worldwide. There is much work to be done, but what we have found is a meaningful sign for a future of more advanced prosthetic control and artificial limbs for lower limb amputees.” 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. Levi said he expects to have patients supporting weight and walking in a laboratory environment in about a year and climbing up and down stairs in two to three years. He added: “Our findings also showed that realtime ankle control was attainable by only using EMG signals from the thigh muscles, leading me and my colleagues to believe that TMR surgery may not be necessary for amputees to regain control of knee and ankle movements with prostheses. “We look forward to applying these findings to our continued research investigating neural control in lower limb amputees and the future development of advanced physical knee and ankle prostheses.”
Oscar Pistorius took two gold medals and broke a world record at the BT Paralympic World Cup in Manchester. Using the FlexFoot® Cheetah® prosthetic foot design from Össur, the South African took the T44 100m title in a personal best of 11.04 before taking almost half a second off his T42/44 400m record to win in a time of 47.28.