An ankle replacement prosthesis includes a tibial component, attached within a cavity formed in the tibia, and a talocalcaneal component, attached within a slot formed within a talocalcaneal compound, previously formed by fusing the talus and the calcaneus. Preferably, the talocalcaneal component includes a neck, to which a head, having a contact surface engaging a contact surface within the tibial component, is adjustably attached. These contact surfaces may both be spherical, with the contact surface of the talocalcaneal component being formed as a ball fitting within a socket formed by the contact surface of the tibial component, or these contact surfaces may include mating feature that limit inversion/eversion rotation of the foot, while providing for dorsal/plantar rotation thereof.