Augmenting clinical evaluation of hemiparetic arm movement with a laboratory-based quantitative measurement of kinematics as a function of limb loading

Background. Kinematic and kinetic measurements used in laboratory settings can quantify upper extremity movement impairment following stroke, but their relationship to clinical methods of evaluating movement impairment is unclear. Objective. To test whether the Arm Coordination Training 3D device (ACT(3D)) could provide a repeatable quantitative measurement of range of motion during upper extremity reaching along a range of functional levels of loads on the arm and correlate with clinical assessments of arm impairment. Methods. Work area during reaching along clockwise and counterclockwise hand paths was measured under 9 limb-loading conditions ranging from no load to twice the weight of the upper extremity in 11 individuals with chronic hemiparetic stroke on 2 separate occasions. Participants were given a battery of clinical assessments that included the Fugl-Meyer Motor Assessment, Chedoke McMaster Stroke Assessment, Reaching Performance Scale, Modified Ashworth Scale, and the Stroke Impact Scale, by a physical therapist who did not know the results of the kinematic studies. Results. A reproducible test-retest reduction in work area was found when participants were required to support up to and beyond the weight of their limb. Work area was correlated with most upper extremity clinical assessments, suggesting criterion validity. Conclusions. Reaching work area during various loading conditions is a robust measurement that quantifies the effect of abnormal joint torque coupling and provides useful data that can be applied in the clinical setting.