Amplitude and frequency analysis of force plate data in sitting children with and without MMC

Objective. To investigate if force plate measurements can be used to detect postural sway differences in sitting children with and without myelomeningocele (spina bifida). Background. The postural sway has not been investigated in children with myelomeningocele previously. Since many of these children are not able to stand independently, force plate measurements during sitting could be one way to detect differences in their postural sway compared to normal children. However, there is very little published regarding assessment of seated postural sway. Methods. Force plate measurements on 15 six years old children with myelomeningocele and 20 age-matched normal children were analysed. The standard deviation and the median frequency of the horizontal ground reaction force were used to characterise the body sway. Results. The standard deviation of the force was larger only for some of the children with myelomeningocele as compared to the control group. The median frequency was significantly lower in the myelomeningocele group as compared to the control group. Visual input and seat base inclination did not influence the postural sway significantly. Conclusions. The results show that frequency analysis can be used to detect fundamental differences in postural sway that can not be observed visually.