An ankle prosthesis comprising a tibial implant, a talar implant and an insert to articulate the implants. The top face of the tibial implant having an anchoring fin, and the bottom face is articulated with the top surface of the insert. The bottom face of the talar implant includes an anchor to the talar bone, and the top face is articulated with the bottom surface of the insert. The articulation surface being saddle-shaped and including a longitudinal central groove allowing the insert to move longitudinally and rotate transversely. The top face of the tibial implant includes, on its anterior edge, a shield covering the bottom anterior portion of the tibia, and the tibial face is inclined and forms an angle with the horizontal of between 15° and 45°. Passages are provided in the shield for bone screws passing through in an ascending manner and open on the inclined tibial face.