Diparetic cerebral palsy affects approximately 2 in 1000 people, and can result in gait impairments such as excessive knee flexion and excessive ankle dorsiflexion during the stance phase in gait. Short-term clinical trials using robotic rehabilitation devices have shown gait improvements comparable to invasive multilevel surgery for spastic cerebral palsy. This study aimed to determine if the stiffness of articulated forms of ankle-foot orthoses influences the effectiveness of a powered knee-ankle-foot orthosis on crouch gait reduction. It was hypothesized that AFO stiffness would be an important factor influencing crouch gait in individuals with diparetic cerebral palsy when walking with a powered KAFO. A pilot study with three participants with diparetic cerebral palsy causing crouch gait was conducted to evaluate the effects of varying ankle stiffness of ankle-foot orthoses on sagittal plane kinematics and kinetics while walking with a powered-knee knee-ankle-foot orthosis. Experimental ankle foot orthoses were made to enable adjustable joint stiffness during the experiment. Optical motion capture and in-ground force plates were used to capture gait biomechanics during self-selected walking for eight experimental conditions. Overall, the presence or absence of a powered knee and AFO stiffness had an impact on ankle and knee biomechanics during walking. Across conditions using the powered KAFO, the greatest improvement in crouch at both the ankle and knee was observed with the highest-stiffness experimental AFO. Ankle torque increased with AFO use, while knee torque increased with the powered KAFO but was lower when paired with the experimental AFOs. Ankle power was not consistently improved by the KAFO and AFO conditions, while knee power generally increased with KAFO use and was highest in the powered conditions. This study provides preliminary results on the impact of ankle-foot orthoses in conjunction with a powered knee exoskeleton, and may inform further exploration of treatment of pathological gaits using robotic assistive devices.
Finnegan et al. (Tue,) studied this question.