Spatiotemporal parameters from instrumented motion analysis represent clinical measurement of upper limb function in children with cerebral palsy

Background: There are various tools that measure upper limb function in children with cerebral palsy(CP) clinically, but these measurement methods are examiner-dependent and scale values are not proportional to the upper limb function which makes it difficult to quantify the function.

Research question: The purpose of this study was to investigate whether the new parameters derived from 3D motion analysis reflect the upper limb function which measured by Melbourne Assessment 2 (MA2) in children with cerebral palsy (CP) compared to the clinical measurements.

Methods: Forty children with CP (24 boys, 16 girls; mean [SD] age, 6 years 11 months [3 years 5 months]) were recruited. Motion capture was conducted during phases T1-T4 of Reach and Grasp Cycles. New parameters (movement time, number of movement units, index of curvature) were derived from wrist marker data. Range of motion (ROM), accuracy, dexterity, and fluency of unilateral upper limb function were assessed using MA2. Spearman rank coefficients were determined to evaluate correlations between MA2 and the new parameters.

Results and significance: Index of curvature correlated negatively with MA2 accuracy scores during T1 (r_s -0.347, p < 0.05), T2 (r_s -0.471, p < 0.01), and T3 (r_s -0.660, p < 0.01). Number of movement units correlated negatively with MA2 ROM, accuracy, and fluency scores during T1 (ROM r_s -0.334; accuracy r_s -0.331; fluency r_s -0.375; p < 0.05) and T3 (ROM r_s -0.499; accuracy r_s -0.531; fluency r_s -0.515; p < 0.01). Index of curvature and number of movement units are objective, simple parameters showing fair to good correlation with MA2 accuracy and fluency of upper limb function.