FIELD OF THE INVENTION

The present invention relates to a prosthetic ankle including a flat section.

TECHNICAL BACKGROUND

The present invention relates to the technical field of prosthetic ankles intended to allow for an orthopaedic treatment of the articulation of the ankle by implantation of prosthetic elements to return at least partially the articular anatomy of the ankle. Indeed, following wear or a traumatic shock, it is known that total or partial damage of the articular interlining of the ankle occurs.

Numerous prosthetic ankles have been developed.

They generally comprise two portions; a tibial portion provided at the end of the tibia, a talus portion provided in the upper portion of the talus, each of the two portions including an articular surface, as well as a pad inserted between the tibial portion and the talus portion with two contact surfaces likely to supplement the articular surfaces. For example, such prosthetic ankles are described in the documents FR 2 760 353 and WO 03/075802.

Document FR 2 905 259 describes a prosthetic ankle comprising a talus portion, a pad and a tibial portion having a curved, concave articular surface constituted of a spheric portion extending over all of said articular surface.

These stressed systems only make it possible to reproduce partially all of the freedoms of movements of the natural articulation of the ankle since the friction surface between the two implants is very distant from the theoretical physiological shape of the natural articulation of the ankle.

There is therefore a real need to propose a prosthetic ankle, of which the shapes make it possible to improve the freedom of movements while allowing for a correct centring of stresses and to reduce the stresses, in particular at the level of the anchorages, and to improve said anchorages, in particular in order to obtain a better bone recovery and to improve the articular amplitudes in a front plane.

SUMMARY OF THE INVENTION

The invention first relates to a prosthetic ankle comprising a tibial portion likely to be connected to the lower end of a tibia, a talus portion likely to be connected to a talus, as well as a pad inserted between the tibial portion and the talus portion, the tibial portion including an articular surface likely to engage with a contact surface of the pad and the talus portion including a curved articular surface likely to engage with a contact surface of the pad, characterised in that the articular surface of the tibial portion is curved, concave, and comprises a flat section forming an extension to the rear of said articular surface.

According to an embodiment, the flat section has a width comprised between 2 and 8 mm, preferably between 4 and 6 mm.

According to an embodiment, the tibial portion has a length comprised between 20 and 100 mm, preferably between 35 and 85 mm and a width comprised between 10 and 40 mm, preferably between 15 and 30 mm.

According to an embodiment, the articular surface of the tibial portion comprises a spheric portion extending over a portion of said articular surface.

According to an embodiment, the spheric portion of the articular surface of the tibial portion has a bend radius R likely to vary from 30 to 90 mm, preferably of the order of 50 mm, and if necessary, a second bend radius R′ different from the radius R likely to vary from 20 to 80 mm, preferably of the order of 50 mm.

According to an embodiment, the articular surface of the tibial portion is slightly inclined to the rear of the foot.

According to an embodiment, the articular surface of the tibial portion is inclined in the direction of the flat section.

According to an embodiment, the articular surface of the tibial portion is inclined in the direction of the rear portion of the articular surface.

According to an embodiment, the articular surface of the talus portion has a bend radius r about the longitudinal axis likely to vary from 20 to 30 mm, preferably of the order of 24 mm.

According to an embodiment, the tibial portion comprises anchorage means with a removable pin.

According to an embodiment, the removable pin comprises two symmetrical recesses arranged in the lower portion of the pin, of which the shapes are likely to engage with the outer surfaces of two parallel cylinders integral with tibial portion, the pin having in the lower portion, a diameter greater than the distance separating the two cylinders.

According to an embodiment, the pin comprises a transversal orifice allowing for the implementation of a screw, a cotter or a linchpin likely to pass through at least partially the lower portion of the tibia.

According to an embodiment, the talus portion comprises anchorage means with at least one stop arranged under the talus portion, at the level of the rear edge, to prevent the tilting of the talus portion towards the front of the foot.

The present invention makes it possible to overcome the disadvantages of the state of the art.

To this end, the invention aims for a prosthetic ankle comprising a tibial portion likely to be connected to the lower end of a tibia, a talus portion likely to be connected to a talus, as well as a pad inserted between the tibial portion and the talus portion, the tibial portion including an articular surface likely to engage with a contact surface of the pad and the talus portion including a curved articular surface likely to engage with a contact surface of the pad, characterised in that the articular surface of the tibial portion is curved, concave, and further comprises a flat section forming an extension to the rear of said articular surface of the tibial portion.

