A team of researchers has demonstrated the feasibility of extracting neural information from above-knee muscles that is suitable for controlling both knee and ankle movements of powered lower-limb prostheses during non-weight bearing activates. The study was published June 19, as a provisional publication, in the Journal of NeuroEngineering and Rehabilitation.
For their study, the researchers investigated a control system that relied on information extracted from myoelectric signals to control a lower-limb prosthesis while amputee patients were seated. Sagittal plane motions of the knee and ankle can be accurately (>90 percent) recognized and controlled in both a virtual environment and on an actuated transfemoral prosthesis using only myoelectric signals measured from nine residual thigh muscles. Patients also demonstrated accurate (~90 percent) control of both the femoral and tibial rotation degrees of freedom within the virtual environment. A channel subset investigation was completed and the results showed that only five residual thigh muscles are required to achieve accurate control.
“To our knowledge, this is the first time EMG signals from the residual muscles of transfemoral amputees have been used to directly control both knee and ankle movements,” the researchers said.
Current work is focusing on modifying the powered-knee prosthesis control system so that neural information can be used during weight bearing activities.