An electromyographic analysis of obligatory (hemiplegic cerebral palsy) and voluntary (normal) unilateral toe-walking

This study compares lower extremity muscle activation during gait in patients with hemiplegic cerebral palsy (CP) with healthy subjects mimicking the patients. The purpose was to understand the differences between obligatory toe-walking as observed in hemiplegic CP gait and voluntary toe-walking. The results contribute to a better understanding by distinguishing between primary deviations in muscle activity as a direct consequence of the underlying neurological pathology of hemiplegic CP and secondary, compensatory deviations due to the biomechanics of toe-walking. Surface electromyographic (EMG), kinematic and kinetic data were compared between a group of 12 hemiplegic CP patients and a group of 10 healthy subjects walking normally and when mimicking hemiplegic gait. Integrated 3D gait analysis was performed with simultaneous EMG recordings of the medial gastrocnemius, tibialis anterior, rectus femoris, and semitendinosus muscles bilaterally. The EMG pattern of the toe-walking leg in the mimicking subjects was modified in gastrocnemius and tibialis anterior as compared with normal gait. This modified muscle activation pattern showed strong similarities to that of the patients and therefore can be regarded, at least in part, as activity required for toe-walking. A possible primary gait abnormality was observed in the rectus femoris where the patients showed a burst of EMG activity in mid-swing phase in contrast to the mimicking subjects who showed normal EMG during this phase.