Background: Stroke survivors often experience abnormal posture control, which affects balance and locomotion. The ankle strategy is important in maintaining static balance. Prolonged spasticity may result in biomechanical changes at the ankle joint, which may cause balance disorders. The intelligent stretching device may decrease the stiffness of the ankle and improve balance. The purpose of this study was to investigate the effects of robot-aided ankle rehabilitation of stroke survivors with ankle spasticity and the correlations between biomechanical properties and balance in these patients.
Methods: Twenty inpatients post stroke with ankle spasticity performed 20 minutes of stretching treatment for 2 weeks. The study group used a rehabilitation robot to stretch the spastic ankle plantar flexors under intelligent control and the control group received manual stretching. Outcome measures included biomechanical, clinical evaluations and Pro-Kin balance test.
Results: After training, significant improvements were found in both groups in the active range of motion, muscle strength, Berg Balance Scale, Fugl-Meyer Motor Assessment of Lower Extremity, Postural Assessment Scale for Stroke Patients, 6-minute walk test, and Modified Barthel Index (P<0.05); significant decreases were found in the study group in dorsiflexion stiffness, Modified Ashworth Scale, trajectory lengths, elliptical trajectory, standard deviation medial/lateral, average speed forward/backward with eyes closed, and standard deviation forward/backward with eyes open (P=0.001, P=0.037, P=0.028, P=0.019, P=0.016, P=0.001, and P=0.033, respectively); dorsiflexion stiffness was positively correlated with the Pro-Kin balance test outcomes: ellipse area, trajectory length, average speed forward/backward, average speed medial/lateral with eyes open ( =0.352, P=0.026; =0.522, P=0.001; =0.045, P=0.004; =0.433, P=0.005, respectively); dorsiflexion stiffness was correlated with the Modified Ashworth Scale ( =0.265, P=0.041); the study group improved significantly more than the control group in the activities of daily living after training (P =0 .017).
Conclusions: The results suggested that robot-aided ankle rehabilitation had a positive effect on the biomechanical properties of the spastic ankle, and it may be feasible to improve balance post-stroke. Ankle dorsiflexion stiffness affected balance poststroke significantly; it may be a sensitive indicator for evaluating balance.
Trial registration: www.chictr.org.cn ChiCTR1900022128. Registered 21 February 2020. Retrospectively registered.