Adaptation of gait initiation in children with unilateral idiopathic clubfoot following conservative treatment.

Children with unilateral clubfoot (CF) treated conservatively have residual foot deformities and triceps surae m. atrophy. Using surface electromyography of tibialis anterior (TA), gastrocnemius (GA), and peroneus longus muscles, simultaneously with ground reaction forces recordings, the present work assesses the influence of this pathology on the gait initiation process. Ten children with CF and 10 healthy children were investigated. In children with CF, the velocity of the centre of gravity (CG) at the end of gait initiation did not differ from that of healthy children, because of adaptations of anticipation and execution phases. CG velocity at the end of anticipation was lower in children with CF than in healthy children when the swing foot was the affected one, indicating that propulsion was less efficient in this condition. It is shown that this resulted from alterations in anticipation duration, initial centre of pressure position and TA and PL excitations. Execution was shortened when support was provided by the pathological foot: the motor program was adapted to shorten the phase during which equilibrium control might be deficient. Biomechanical characteristics of the execution phase of children with CF did not depend on the swing foot. This indicated that the sound foot cannot be used as a control for accessing residual deficiencies.