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Time–frequency changes in electromyographic signals after hamstring lengthening surgery in children with cerebral palsy
Journal article   Peer reviewed

Time–frequency changes in electromyographic signals after hamstring lengthening surgery in children with cerebral palsy

Richard T. Lauer, Brian T. Smith, Patricia A. Shewokis, James J. McCarthy and Carole A. Tucker
Journal of biomechanics, v 40(12), pp 2738-2743
2007
DOI: https://doi.org/10.1016/j.jbiomech.2007.01.001
PMID: 17328900
Featured in Collection :   UN Sustainable Development Goals @ Drexel

Abstract

Cerebral palsy Electromyography Hamstring lengthening Locomotion Wavelet analysis
Increased knee flexion during stance is a common gait deviation in the child with cerebral palsy (CP), with distal hamstring lengthening surgeries being an accepted course of treatment. Post-operatively, improvements in gait kinematics have been reported, however little change is noted in the patterns of muscle activity as portrayed by onset and offset timing in the surface electromyographic (sEMG) signals. Similar analysis based on the frequency content of the sEMG signals has seldom been applied, yet may provide additional insight into changes in muscle activity in response to surgery. The purpose of this study was to determine if changes in the time–frequency characteristics of the sEMG, extracted using wavelet analysis techniques, corresponded to improved gait kinematics observed post-surgical intervention, and whether there existed a relationship between frequency characteristics of the sEMG signals and the type of surgery required to correct gait kinematics. Data were collected from 16 children with typical development (TD) and 17 children with CP pre- and post-surgery. Muscle activity was recorded from the medial hamstring (MH) and vastus lateralis (VL) muscles, processed using the wavelet transform, and analyzed using functional principal component analyses (PCA). Results indicated that frequency differences were present pre-operatively depending if surgery was to be performed bilaterally or involved bone modification. Post-operatively, frequency characteristics of the VL more closely approximated those observed in children with TD, agreeing with the improved gait kinematics. MH characteristics, however, for the surgical groups demonstrated a deviation away for TD reflecting the altered muscle structure.

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15 citations in Web of Science
15 citations in Scopus

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#3 Good Health and Well-Being

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Collaboration types
Domestic collaboration
Web of Science research areas
Biophysics
Engineering, Biomedical
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