Knee joint movement and muscle activity changes in stroke hemiplegic patients on continuous use of knee-ankle-foot orthosis with adjustable knee joint

[Purpose] We aimed to evaluate knee joint movement and muscle activity ratio changes in stroke hemiplegic patients in recovery phase after using a knee-ankle-foot orthosis with an adjustable knee joint for 1 month; we also aimed to discuss the practical implications of our findings. [Participants and Methods] The participants were 8 hemiplegic patients in the recovery phase of stroke who were prescribed knee-ankle-foot orthosis with adjustable knee joint. We measured knee joint angles and electromyographic activity of the vastus medialis and biceps femoris during walking in two conditions: the knee-ankle-foot orthosis knee joint fixed in the extended position and the knee joint moved from 0° to 30° in the flexion direction. Measurements were taken 2 weeks after completion to account for habituation of the orthosis and repeated 1 month later. [Results] When the knee joint was moving from 0° to 30° in the flexion direction, the knee joint angle at initial contact and the minimum flexion angle of the gait cycle decreased significantly between the first and second measurements. When knee joint flexion was 30°, the muscle activity ratio of the vastus medialis increased significantly in the loading response and mid-stance compared to when it was fixed. [Conclusion] Setting the knee joint of a knee-ankle-foot orthosis in accordance with the knee joint movement may increase the muscle activity ratio of the vastus medialis from loading response to mid-stance.