Are electromyographic patterns during gait related to abnormality level of the gait in patients with spastic cerebral palsy?

PURPOSE One of the aims of the treatment in ambulant cerebral palsy (CP) patients is improvement of gait. The level of gait pathology is assessed by instrumented gait analysis, including surface electromyography. The aim of this study was to investigate the relation of the abnormality level of the gait and the co-contraction of the agonist-antagonist muscles, and relation between symmetry left /right leg in gait and symmetry of muscular activity. METHODS Fifty one patients with cerebral palsy underwent clinical assessment and instrumented gait analysis, including surface electromyography. Signals were bilaterally collected from rectus femoris, medial and lateral hamstrings, tibialis anterior, lateral gastrocnemius and gluteus maximus. In older children additionally signals from soleus and lateral vastus were recorded. Sixteen gait variables were selected to calculate Gillette Gait Index, separately for left and right leg. From the envelopes a series of cross-correlation coefficients were calculated. RESULTS Weak correlations were found between averaged agonistantagonist correlation coefficient and Gillette Gait Index. Differences between hemiparetic less-involved legs, hemiparetic spastic legs, and diplegic legs were found for co-contraction of rectus femoris and biceps femoris and for averaged agonist-antagonist co-contraction. The differences between hemiparetic and diplegic groups were found for some muscle correlation coefficients. CONCLUSIONS The results obtained in this study show that the activity pattern of the leg muscles is specific to a given patient, and the dependence of the kinematics pathology on the abnormal activation pattern is not a direct one.