During phases of initial foot contact and single limb support, co-contractions may enhance stability as a limb stiffening strategy, according to results of a recent study in the Journal of NeuroEngineering and Rehabilitation.
Researchers enrolled nine unilateral traumatic transtibial amputees and five matched controls. Activation from the tibialis anterior, medial gastrocnemius, vastus lateralis and biceps femoris of the residual, intact and control limbs was recorded by surface electromyography. To obtain a linear envelope of activation patterns, researchers applied a series of filters to the signal.
During all phases of gait, study results showed that a co-contraction of the ankle muscles was greater in the residual limb vs. the intact and control limbs. Similarly, knee muscle co-contraction was also greater in the residual limb vs. control limb.
“The findings of this study have revealed significant limb differences in ankle muscle co-contraction. Additionally, there were significant differences in co-contraction levels of the knee musculature between the residual and control limbs,” the researchers concluded. “These co-contractions may be a means for enhancing stability during trans tibial amputee gait and therefore the existence of co-contractions should be considered during the development of future myoelectric controllers.”
For more information:
Journal of NeuroEngineering and Rehabilitation. 2012;doi:10.1186/1743-0003-9-29.