The effect of lower extremity selective voluntary motor control on interjoint coordination during gait in children with spastic diplegic cerebral palsy.

Damage to motor tracts in the periventricular white matter is a primary etiology in spastic diplegic cerebral palsy (CP). These tracts are responsible for the production of selective voluntary motor control (SVMC). Lower extremity motor control has been suggested as being an important predictor of improvement following interventions. While there are multiple impairments in spastic CP, the inability to perform purposeful voluntary movement is a critical factor in determining functional ability that merits investigation. The purpose of this study was to examine the relationship between SVMC ability and hip and knee coordination during the swing phase of gait in participants with spastic CP. Gait analysis and SVMC assessments were conducted for 15 participants with CP. Relative phase analysis was used to calculate the minimum relative phase (MRP) angle during swing; a measurement of interjoint coordination between the hip and the knee. SVMC ability was measured using the Selective Control Assessment of the Lower Extremity (SCALE) tool. Significant correlations were found between SCALE scores and both MRP values (p<0.0001) and duration of out-of-phase movement (p<0.005) during swing. These findings supported our hypothesis that SVMC ability is related to a patient's ability to move in an uncoupled pattern during the swing phase of gait (i.e., extending the knee while flexing the hip). An understanding of influence of SVMC on swing phase gait mechanics may help establish appropriate goals for interventions, in particular hamstring lengthenings.