Trunk Compensation and Inter-joint Coordination of an Unilateral Upper Limb Circle Tracing Task in Chronic Stroke Patient

Background and purpose. Following brain lesions, stroke patients suffered limited arm movements. Our study aimed to investigate the trunk compensation and inter-joint coordination of unilateral upper limb movements in able-bodied and hemiparetic groups on a circle tracing task. Methods. Nine able-bodied subjects and nine hemiparetic subjects were recruited in the study. Participants were asked to trace a circle on a table, at a self-selected pace. An evaluation framework was established to investigate features of trunk recruitments and inter-joint coordination. Correlation among features and clinical assessment scores were then investigated. Results. Hemiparetic participants accomplished the circle tracing task with more trunk recruitments, accompanied with abnormal movement pattern of shoulder and elbow. More switch times of movements directions in the hemiparetic group was also quantified in the study. The axis ratio of the tracing trajectory without trunk compensation was correlated with the amount of executing shoulder adduction and elbow extension on hemiparetic subjects. The orientation of the tracing trajectory was correlated with the degrees of trunk compensation. Conclusions. A framework to evaluate trunk compensation and inter-joint coordination was suggested. The effect of trunk involvement on the tracing trajectory was quantified. Among the hemiparetic group, trunk compensation might be relevant to the orientation angles of the trajectory. In addition, the outcomes of shoulder adduction and elbow extension combination might be relevant to the axis ratio of the tracing trajectory without trunk compensation.