Design of a Novel Two Degree-of-Freedom Ankle-Foot Orthosis

An ankle-foot orthosis (AFO) is commonly used to help subjects with weakness of ankle dorsiflexor muscles due to peripheral or central nervous system disorders. Both these disorders are due to the weakness of the tibialis anterior muscle, which results in the lack of dorsiflexion assist moment. The deformity and muscle, weakness of one joint in the lower extremity influences the stability of the adjacent joints, thereby requiring compensatory adaptations. We present an innovative ankle-foot orthosis (AFO). The prototype AFO would introduce greater functionality over currently marketed devices by means of its pronation-supination degree of freedom in addition to flexion/extension. This orthosis can be used to measure joint forces and moments applied by the human at both joints. In the future, by incorporation of actuators in the device, it will be used as a training device to restore a normal walking pattern.