Effect of using knee extension aid for gait training in subacute hemiplegia: a randomized controlled trial

[Purpose] In normal gait, the knee flexes approximately 60° during the swing phase, and the lower leg's inertial force contributes to knee extension during terminal swing, enabling heel-first initial contact and energy-efficient gait. However, slow-walking individuals with hemiplegia generate insufficient inertial force, resulting in inadequate knee extension during terminal swing and difficulty achieving heel strike. When initial forefoot contact occurs, ankle plantar flexors may become excessively active during loading response, reinforcing abnormal movement patterns. This randomized controlled trial investigated the therapeutic effect of a knee extension aid during terminal swing. [Participants and Methods] We randomized 30 hemiplegic inpatients who could perform gait training using an ankle-foot orthosis in convalescent rehabilitation wards at five facilities in Japan into two groups. The intervention group used the ankle-foot orthosis and knee extension aid during gait training, while the control group used the ankle-foot orthosis alone. We measured knee joint angles during comfortable-speed walking before and after 2 weeks of gait training. [Results] In the intervention group, knee joint angles during terminal swing significantly decreased by approximately 4° after 2 weeks. [Conclusion] The knee extension aid may facilitate heel-first initial contact and reduce abnormal ankle muscle activation by decreasing knee flexion during terminal swing.