ankle-foot orthosis (AFO)

ankle-foot orthosis (AFO), any of a variety of protective external devices that can be applied to the ankle area to prevent injury in a high-risk athletic activity, to protect a previous injury such as a sprain, or to assist patients with chronic joint instability with walking. An AFO is often used by patients unable to dorsiflex the ankle during gait. It may be used to maintain anatomical position in a person that has a footdrop.