Surgical instrumentation assembly for positioning an ankle prosthesis

A surgical instrumentation assembly for positioning an ankle prosthesis, the ankle prosthesis including a tibia implant and a talus implant provided with a talo-calcaneal anchoring keel, the instrumentation assembly comprising:

• a tibial phantom adapted for attachment to the tibia of a patient, and an aiming guide, adapted for setting into place an instrumentation element through the talus and the calcaneus of the patient along an axis for implanting the talo-calcaneal anchoring keel, wherein the tibial phantom and the aiming guide mechanically engage with each other to allow movement of the aiming guide with respect to the tibial phantom along an antero-posterior direction and restrict movement of the tibial phantom and the aiming guide relative to each other along vertical and medio-lateral directions, wherein the aiming guide is configured to guide placement of the instrumentation element, wherein the aiming guide defines a through-passage for receiving the instrumentation element, the through-passage positioned to clear the aiming guide with respect to the tibial phantom attached to the tibia while leaving the instrumentation element in place through the talus and the calcaneus, and wherein the aiming guide comprises:
• a main body, which defines the through-passage, and a piercing barrel removably attached to the main body while opening into the through-passage, the piercing barrel adapted for guiding the instrumentation element along the axis for implanting the talo-calcaneal anchoring keel.