The talus and calcaneus make up the two bones of the subtalar joint (STJ), otherwise known as the talo-calcaneal joint. The STJ consists of three articular facets, the posterior, middle and anterior facets. The two physiologic motions of the STJ are supination and pronation. During STJ supination, the talus glides posterior-superiorly on the posterior facet of the calcaneus. During STJ pronation, the talus glides anterior-inferiorly on the posterior facet of the calcaneus. The maximally pronated