Background: Foot drop is characterised by impaired active ankle dorsiflexion, affecting gait quality through foot slap during loading response and reduced toe clearance during swing phase. While ankle-foot orthoses (AFOs) are commonly prescribed, traditional designs often limit natural ankle motion during push-off and cause discomfort. There is a need for AFO designs that provide targeted dorsiflexion assistance while maintaining full plantarflexion mobility. The Rise AFO represents a novel approach, featuring complete ankle mobility and personalised dorsiflexion assistance determined by device stiffness.
Objective: To evaluate the effect of Rise AFO stiffness in reducing tibialis anterior activation and increasing ankle dorsiflexion during loading response and swing phase in healthy participants.
Methods: Ten healthy participants completed a randomised crossover trial comparing seven walking conditions on a treadmill at 4.4 km/h: baseline (no AFO), five Rise AFO stiffness configurations (0.05-0.39 Nm/deg), and a sham device with no stiffness. Primary outcomes included tibialis anterior EMG activity and ankle dorsiflexion. Secondary measures were plantarflexor activity, and sagittal plane knee and hip kinematics. Statistical parametric mapping analysed differences across the gait cycle.
Results: Compared to baseline, all Rise AFO configurations significantly reduced tibialis anterior activity during swing phase. The four stiffest configurations significantly increased swing phase ankle dorsiflexion, demonstrating a linear relationship between stiffness and mid-swing dorsiflexion (R² = 0.87). Loading response kinematics and muscle activity remained unchanged. Plantarflexor activity and proximal joint kinematics were not adversely affected. The sham device had no effect.
Conclusion: The Rise AFO effectively assisted dorsiflexion during swing phase while preserving natural plantarflexion, demonstrating potential as a personalised treatment for foot drop.