Muscle activation patterns during walking from
transtibial amputees recorded within the residual
Powered lower limb prostheses could be more functional if they had access to feedforwardcontrol signals from the user's nervous system. Myoelectric signals are one potential controlsource.
The purpose of this study was to determine if muscle activation signals could berecorded from residual lower limb muscles within the prosthetic socket-limb interface duringwalking.
We recorded surface electromyography from three lower leg muscles (tibilias anterior,gastrocnemius medial head, gastrocnemius lateral head) and four upper leg muscles (vastuslateralis, rectus femoris, biceps femoris, and gluteus medius) of 12 unilateral transtibialamputee subjects and 12 non-amputee subjects during treadmill walking at 0.7, 1.0, 1.3, and1.6 m/s. Muscle signals were recorded from the amputated leg of amputee subjects and theright leg of control subjects.
For amputee subjects, lower leg muscle signals were recordedfrom within the limb-socket interface and from muscles above the knee. We quantifieddifferences in the muscle activation profile between amputee and control groups duringtreadmill walking using cross-correlation analyses.
We also assessed the step-to-step intersubjectvariability of these profiles by calculating variance-to-signal ratios.
We found that amputee subjects demonstrated reliable muscle recruitment signals fromresidual lower leg muscles recorded within the prosthetic socket during walking, which werelocked to particular phases of the gait cycle. However, muscle activation profile variabilitywas higher for amputee subjects than for control subjects.
Robotic lower limb prostheses could use myoelectric signals recorded from surfaceelectrodes within the socket-limb interface to derive feedforward commands from theamputee's nervous system.
Author: Stephanie HuangDaniel P Ferris Credits/Source: Journal of NeuroEngineering and Rehabilitation 2012, 9:55
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