Kinematic evaluation of upper limb impairment in stroke survivors through box and block test and IMUs

Motion analysis is a fundamental methodology for examining upper-limb function. The objective of this study is to find a kinematic index for objectively evaluating the motor impairment caused by a stroke, during the execution of the Box and Block Test (BBT). We tracked trunk and upper limb motion during the test, using seven inertial measurement unit (IMU) sensors placed on trunk and upper limb of both sides. Two groups of subjects were considered. 14 healthy subjects, with a mean age of 47.9 ±18.3. 10 stroke survivors, with a mean age of 53.6 ±19.8 and with different levels of motor disability (with an average value of 54.4 ±6.4 calculated with the Fugl-Meyer scale). Data acquired were processed through validated biomechanical models, dividing BBT task into three subphases: Reaching, Tranfser and Coming Back. Average hand velocity was calculated and compared among the dominant side of healthy subjects, the affected side, and the unaffected side of patients. The ANOVA test was used to study the differences between the two groups. As expected, the mean hand velocity of the affected side of the patients was found to be lower than both the dominant side of the control group and the unaffected side of patients (p<0.05). A correlation study was also conducted between mean velocity and the score that patients achieved in the BBT. For this study, however, the significance was not reached (p>0.1).