Equinovarus in Cerebral Palsy
thesisposted on 28.06.2013 by Joseph J. Krzak
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Equinovarus foot and ankle deformity is most common in children diagnosed with hemiplegic cerebral palsy (CP). A child with equinovarus is limited in gross motor functional skills which can lead to further disability. The cause of this deformity is believed to result from a combination of neuromuscular and biomechanical impairments secondary to an insult to the developing central nervous system. Non-phasic activity of the extrinsic musculature surrounding the foot and ankle create muscular imbalance, atypical positioning and motion of the foot and ankle during locomotion. This dissertation consisted of three experiments that provided fundamental insights into the segmental foot and ankle kinematics during locomotion of children with equinovarus secondary to hemiplegic CP. The first experiment showed that temporal-spatial parameters and triaxial hindfoot kinematics were not affected by the presence of a fine wire electrode inserted into the posterior tibialis. Thus, simultaneous collection of segmental foot and ankle kinematics and fine wire EMG data of the posterior tibilais is acceptable for surgical decision making in this population. The second experiment used a combination of segmental foot and ankle kinematics, principal component analysis (PCA), and K-means cluster analysis to examine the gait deviations associated with the equinovarus foot. Five clinically recognizable subgroups were identified with unique segmental involvement, planar motion, and range of motion (ROM). The third experiment used principal component scores obtained in Experiment 2 to describe changes in segmental foot and ankle motion during walking that resulted from surgical soft tissue balancing procedures for equinovarus. The relationship between segmental foot and ankle kinematics and walking velocity was also evaluated. The results demonstrated that surgical soft tissue balancing procedures result in more neutral hindfoot and forefoot gait kinematics. Individual cases of uncorrected deviations were attributed to two causes: (1) the specific segmental deformity was not identified pre-operatively, and therefore not surgically addressed, and (2) the deformity was so severe that a soft tissue balancing procedure could not correct it. Surgery did not have an effect on walking velocity, and correlation analysis demonstrated that increases in walking velocity were associated with increases in sagittal plane hindfoot range of motion.