Novel kinematic indices for quantifying movement agility and smoothness after cervical Spinal Cord Injury

BACKGROUND:After cervical Spinal Cord Injury (SCI), upper limbmovements made by patients have a lack of smoothness and a hand velocity profile characterized by a high number of velocity peaks. OBJECTIVE: The aim of the present paper is to propose three novel kinematic indices for quantifying movement agility and smoothness, and to analyze their discriminative capability between healthy and pathological people. METHODS: 18 people, healthy and two groups of patients with cervical SCI, participated in the study. Kinematic indices in relation to movement agility and smoothness were computed from hand trajectories and velocity profiles during the performance of the ADL of drinking from a glass. RESULTS: The proposed indices discriminated between healthy and SCI people. The results are greater in healthy than SCI people. Both smoothness indices detected significant differences between healthy and both SCI groups. Moreover, the Agility index showed capacity for discriminating between both patients groups. CONCLUSIONS: The main contribution of this research consists on the proposal of kinematic indices from experimental data, whose results are dimensionless and relative to a pattern of healthy subjects. We hope that kinematic indices proposed are a step toward the standardization of the quantitative assessment of movement characteristics and functional impairments.