Objectives: To identify characteristics of foot pressure distribution in different foot deformities using a computerized insole sensor system, and to identify changes in these parameters after corrective surgery in children with spastic cerebral palsy (CP).
Design: Before-after trial.
Setting: University hospital.
Participants: Sixty-seven limbs of 44 children with spastic CP were assessed (35 equinus, 17 equinovarus, 15 equinovalgus).
Intervention: Orthopedic surgery for foot deformities.
Main outcome measures: Parameters of foot contact pattern, pressure-time integral (PTI), and center of pressure (COP) trajectories were assessed before and at a minimum of 6 months postsurgery, using the F-scan system.
Results: Prior to surgery, the medial midfoot relative impulse, which is PTI normalized by a percentage of the entire foot, differed significantly between foot deformity groups. Relative impulse was high on the lateral column of the foot in the equinovarus group and on the medial column of the foot in the equinovalgus group. Center of pressure index (COPI) and coronal index reflecting the asymmetry of the medial and lateral columns of the foot differed significantly between the equinovalgus and equinovarus groups. After surgery, significant changes occurred in foot contact patterns, including total contact area, contact length, contact width of hindfoot, and the relative impulse of specific areas of the foot. In addition, there were significant changes in the parameters of COP, such as anteroposterior displacement, slope, and velocity.
Conclusions: In dynamic foot pressure measurements using a computerized insole sensor system, the parameters reflecting medial or lateral changes in weight bearing, such as COPI and coronal index, appear to be useful for evaluating abnormalities and improvements after intervention in the frontal plane, such as varus and valgus. Additionally, assessment of parameters in foot contact patterns, PTIs, and COP path trajectories appears to be helpful in evaluating outcomes after corrective surgery.