Development of an active ankle-foot orthosis for hemiplegic patients

In this study, we developed an active ankle-foot orthosis(AAFO) which could control dorsiflexion/plantarflexion of the ankle joint to prevent foot drop and toe drag during walking. To prevent foot slap after initial contact, the ankle joint needs to be actively controlled to minimize forefoot collision with the ground. During late stance, the ankle joint also needs to be controlled to provide toe clearance and to help push-off. 3D gait analyses were performed on a hemiplegic patient under three different gait conditions: gait without AFO(NAFO), gait with the conventional hinged AFO without controlling ankle joint (HAFO), and gait with the developed AFO(AAFO). Results showed that AAFO could prevent not only foot drop by the proper plantarflexion during loading response but also toe drag by sufficient amount of plantarflexion in pre-swing and reasonable dorsiflexion during swing phase, enhancing all temporal gait parameters. The present results indicated that the developed AAFO might have more clinical benefits to treat foot drop and toe drag in hemiplegic patients, comparing with conventional AFOs.