Development and evaluation of ankle muscle trainer with malleolar and subtalar movement actuators and underfoot reaction force sensors during active ankle dorsi-plantarflexion

Abstract

Stroke patients have reduced kinematic characteristics in gait speed, cadence, step kinematics, and range of motion (ROM). Especially, a drop foot is a common symptom during gait after stroke due to the weakness of ankle dorsiflexor. A few robotic ankle systems have been developed to measure and train pathological ankle movements. However, the previously developed systems use orthogonal ankle axis system which reproduces unnatural human ankle movements. So we have developed a robotic device that considers anatomical ankle axes in order to train ankle muscles and to measure the quantities of ankle ROM, and forefoot and hindfoot ground reaction force. We recruited 10 healthy elderly with no history of neurological disorders. Subjects performed a total of three trials with eight repetitions or more of ankle dorsi-plantarflexion using AMT. To investigate the validity of ankle angle measurements in developed AMT, we compared AMT outputs with output ankle kinematics from VICON motion capturing system. We found similar ankle movement pattern between AMT and VICON during active ankle dorsi-plantarflexion movement. The kinematics measured from AMT ankle ROM had a significant correlation with VICON ankle ROM (r = .958, n = 10, p = .00001). Therefore, we confirmed that the validity of ankle angle measurement in developed AMT.