The Arm Profile Score: A new summary index to assess upper limb movement pathology

Abstract

Although three-dimensional movement analysis is being increasingly used to evaluate upper limb (UL) movements, information on how to interpret the complex data is still missing. This paper introduces a new summary index, the "Arm Profile Score" (APS), to evaluate the severity of UL movement pathology based on kinematic data, similar to the "Gait Profile Score". The APS is calculated from the root mean square (RMS) difference between kinematic data of the individual child with UL movement deficits and average data from typically developing children. The APS can be decomposed into 13 Arm Variable Scores (AVS), representing the different joint angles. The APS, together with the AVSs form the "Arm Movement Analysis Profile" (A-MAP). Face and construct validity were established for eight UL tasks in a group of 20 children with hemiplegic cerebral palsy (HCP). Intra-session variability was low for the different tasks, with median inter-quartile ranges below 2°. Correlation analysis showed few significant correlations between the individual AVSs and between the AVS and APS, implying that the A-MAP provides considerably more information compared to the APS only. The APS also showed good correlations with the House classification, and with measures of muscle tone, manual muscle strength and grip strength. This study provides a sound base to use the APS to evaluate UL movement pathology in children with HCP. Further study will need to confirm its value as an outcome measurement.