Analysis of postural control synergies during quiet standing in healthy children and children with cerebral palsy

Objective. To estimate the contribution of body transverse rotation using weighted differential center of pressure signals during quiet standing in healthy children and in children with cerebral palsy. Design. Bode sway was indirectly measured through center of pressure data, which was calculated using dual force platforms. Background. Assessment of postural control synergies using center of pressure data provides a unique method for center of mass data analysis in characterizing complex balance sway. Methods. Using dual force platforms, linear expressions for the coordinates of right and left center of pressure signals were developed to identify and characterize balance control synergies during quiet standing. Subjects were also tested during eyes open and eyes closed trials to determine the significance Of visual input on these control synergies. Results. The limb protraction/retraction control was found to be dominant during medial-lateral sway. whereas the estimated body transverse rotation contribution was found to be more significant than the previously reported measures of anterior-posterior balance. These findings were consistent in healthy children and in children with cerebral palsy during both eyes open and eyes closed trials. Conclusion. The weighted differential center of pressure signals show that the estimated body transverse rotation contribution is significant in healthy children and critical for postural stability in children with cerebral palsy.