An orthotic device having a thin, flexible material defining a plantar wall and lateral, medial and posterior sidewalls. A fastening mechanism releasably secures the lateral and medial sidewalls together. In some embodiments, the plantar wall defines a laterally extending distal trimline positioned distal of the first metatarsal head and proximal of the third, fourth and fifth metatarsal heads when the foot is secured within the orthotic device. In other embodiments, the device includes a heel post having a distal terminal edge with a medial portion extending into the arch proximal to the navicular bone and a lateral portion positioned proximal of the arch. In still other embodiments, an elongate strip of padding material projects inwardly below and proximate the medial malleosus and the lateral malleosus and is positioned to inhibit withdrawal of the calcaneous bone. A method of manufacturing an orthotic device is also disclosed.