Effects of articulated ankle–foot orthosis dorsiflexion range of motion on lower-limb joint kinematics during gait in individuals post-stroke

Adjusting the range of motion (ROM) and spring stiffness of ankle–foot orthoses (AFOs) for individuals post-stroke enables customized functionality and targeted support during specific phases of the gait cycle. Modifications to dorsiflexion ROM or spring stiffness theoretically influences the second and third rockers of gait. Understanding these effects is crucial for optimizing gait in individuals post-stroke. This study investigated the impact of dorsiflexion ROM adjustments in multi-function articulated AFOs on ankle, knee, and hip kinematics during gait in individuals post-stroke. Nine participants were tested across six AFO settings, including three dorsiflexion ROM levels (0°, 5°, 10°) with two spring stiffness levels (low stiffness = 200 N/mm, high stiffness = 515 N/mm) of the Triple Action ankle joint. Kinematic data were collected using a 3D motion capture system, and joint angle parameters were analyzed throughout the gait cycle. The results showed that increasing dorsiflexion ROM significantly increased the maximum dorsiflexion angle of the ankle and decreased the maximum extension angle of the knee, with no significant effects on hip joint kinematics or walking speed. Increased ankle dorsiflexion facilitates tibial progression during the second rocker of gait, enhancing walking efficiency. However, the decrease in knee extension angle or increase in knee flexion angle may pose challenges to knee stability. This study suggests that dorsiflexion ROM of articulated AFOs should be tailored: individuals with stable knee joints may benefit from increased dorsiflexion ROM to optimize the second rocker, while those with unstable knees may require reduced dorsiflexion ROM to enhance stability.