Upper limb functional assessment of children with cerebral palsy using a sorting box.

We investigated the use of a sorting box to obtain a quantitative assessment of upper limb motor function in children with cerebral palsy. In our study, children with and without cerebral palsy placed and removed geometrical objects of a sorting-box while their wrist position was monitored by a camera-based, motion-tracking system. We analyzed three different smoothness metrics (logarithmic dimensionless jerk, spectral arc-length and number of peaks) together with time to task completion. Our results suggest that smoothness metrics are an effective tool to distinguish between impaired and non-impaired subjects, as well as to quantify differences between the affected and less-affected sides in children with hemiparetic cerebral palsy.