Prototype and evaluation of an articulated plastic ankle-foot orthosis with a built-in T-strap

Abstract

In a previous study, we have demonstrated in healthy subjects that a shoehorn-type ankle-foot orthosis with a T-strap is effective in correcting adduction, which is the horizontal movement of the ankle joint in resting standing position. However, in individuals with increased muscle tone in the plantarflexor muscles requiring a T-strap, use of an articulated ankle-foot orthosis with dorsiflexion assist is recommended, to avoid range-of-motion limitation occurring in the ankle joint. In this study, we fabricated a prototype ankle-foot orthosis by incorporating a T-strap in a plastic ankle-foot orthosis with a Tamarack ankle joint for dorsiflexion assist and plantarflexion stop. We also evaluated the effectiveness of the prototype in correcting ankle joint inversion in healthy subjects. From the results of gait measurement, the angle of ankle joint inversion was reduced during the stance phase excluding initial contact when the ankle-foot orthosis with T-strap was worn compared to when the orthosis without T-strap was used. These results demonstrated the correction effect of the prototype ankle-foot orthosis.