The development of a knee locker with close-loop functional electrical stimulation (FES) for hemiplegia in gait training

Purpose: A knee locker with closed-loop functional electrical stimulation (FES) system has beendeveloped to prevent the quadriceps weakness and the drop-foot of the hemiplegia during gait training. Method: The FES system is triggered by a footswitch on the heel of the disabled foot to stimulate the tibialis anterior muscle for dorsi-flexion and to turn-off the knee locker in the swing phase through the main controller. Besides, the footswitch on the heel of the affected-side can be used to stimulate the quadriceps and to turn-on the knee locker for quadriceps weakness in the stance phase. Results: It is revealed that the mean velocity, cadence, stride length, active ankle motion range, and functional ambulation category (FAC) have improved significantly from 0.15 ± 0.04 m sec^-1, 43.3 ± 15.4 steps min^-1, 0.36 ± 0.11 m, 15°, level 2 to 0.43 ± 0.21 m sec^-1, 69.4 ± 19.1 steps min^-1, 0.73 ± 0.17 m, 40°, level 4 respectively for the patient. A paired t-test indicated that differences in the electromyography (EMG) of the tibialis anterior and the quadriceps muscles between patient's disabled (affected-side) foot and normal (unaffected-side) foot are not significant (p > 0.05) after 16 weeks of training. Conclusions: It is concluded that this new knee locker with closed-loop FES system is capable of providing the hemiplegia with restoration to regular walking after appropriate gait training.