Cerebral palsy (CP) is a complex syndrome, with multiple interactions between joints and muscles. Abnormalities in movement patterns can be measured using motion capture techniques, however determining which abnormalities are primary, and which are secondary, is a difficult task. Deformity of the foot has anecdotally been reported to produce compensatory abnormalities in more proximal lower limb joints, as well as in the contralateral limb. However, the exact nature of these compensations is unclear. The aim of this paper was to provide clear and objective criteria for identifying compensatory mechanisms in children with spastic hemiplegic CP, in order to improve the prediction of the outcome of foot surgery, and to enhance treatment planning. Twelve children with CP were assessed using conventional gait analysis along with the Oxford Foot Model prior to and following surgery to correct foot deformity. Only those variables not directly influenced by foot surgery were assessed. Any that spontaneously corrected following foot surgery were identified as compensations. Pelvic rotation, internal rotation of the affected hip and external rotation of the non-affected hip tended to spontaneously correct. Increased hip flexion on the affected side, along with reduced hip extension on the non-affected side also appeared to be compensations. It is likely that forefoot supination occurs secondary to deviations of the hindfoot in the coronal plane. Abnormal activity in the tibialis anterior muscle may be consequent to tightness and overactivity of the plantarflexors. On the non-affected side, increased plantarflexion during stance also resolved following surgery to the affected side.
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