Set of prosthetic elements for a tibial prosthetic assembly
A tibial prosthetic assembly generally comprises a base ( 6 ) intended to be connected to a tibia and a shoe adapted to be fixedly mounted on the base. This shoe defines a prosthetic articulating surface intended to cooperate with a femoral element ( 2 ) and presenting an anterior spine ( 56 ) on either side of which are located two glenoidal cavities ( 54, 55 ) for receiving femoral condyles ( 14, 15 ). In order to form such an assembly, the surgeon has at his disposal a set comprising the base ( 6 ) and a plurality of shoes which are adapted to be assembled in respective inherent angular positions in each of which the longitudinal axis of the anterior spine ( 56 ) of each shoe forms a predetermined angle with the antero-posterior median axis of the base ( 6 ). Application to the domain of prostheses of the knee joint, particularly of humans.
1 . Set of prosthetic elements for a tibial prosthetic assembly ( 4 ), comprising a base ( 6 ) intended to be connected to the upper end of a tibia and defining a median antero-posterior axis (X-X), said tibial assembly comprising said base ( 6 ) and a shoe adapted to be fixedly mounted on the base ( 6 ) and defining a tibial prosthetic articulating face ( 52 ) intended to cooperate with a femoral prosthetic element ( 2 ), which articulating surface presents both two glenoidal cavities ( 54 , 55 ) for receiving internal ( 14 ) and external ( 15 ) condyles of the femoral element ( 2 ) and an anterior spine ( 56 ) which longitudinally defines an axis (Y-Y) on either side of which are located these glenoidal cavities, characterized in that said set comprises a plurality of shoes ( 8 A, 8 B, 8 C, 8 D) adapted to be fixedly mounted on the base ( 6 ) in respective angular positions in each of which the axis (Y-Y) of the anterior spine ( 56 ) of each shoe forms, with the median axis (X-X) of the base, a predetermined angle (α A , α B , α C , α D ), at least one of these predetermined angles being non-zero and another possibly being zero.
2 . Set according to claim 1 , characterized in that the shoes ( 8 A, 8 B, 8 C, 8 D) of the set are chosen from shoes of which the axes (Y-Y) of the spines ( 56 ) form with the median axis (X-X) of the base ( 6 ) angles (α A , α B , α C , α D ) whose respective values are included between about 0 and 15°.
3 . Set according to claim 2 , characterized in that said angles (α A , α B , α C , α D ) formed between the axes (Y-Y) of the spines ( 56 ) of the shoes ( 8 A, 8 B, 8 C, 8 D) of the set and the median axis (X-X) of the base ( 6 ) are respectively worth about 0, 2, 4, 6 and 8°.
4 . Set according to claim 1 , characterized in that each shoe ( 8 A, 8 B, 8 C, 8 D) of the set is provided with a face ( 40 ) for assembly opposite the articulating surface ( 52 ), said face bearing means ( 44 ) for fixing on the tibial base ( 6 ) adapted to cooperate with this base by complementarity of shapes.
5 . Set according to claim 4 , characterized in that the assembly faces ( 40 ) of the shoes ( 8 A, 8 B, 8 C, 8 D) of the set are substantially identical to one another.
6 . Set according to claim 4 , characterized in that the means ( 44 ) for fixing each shoe ( 8 A, 8 B, 8 C, 8 D) of the set comprises a lip ( 46 ) for clipping in a substantially complementary groove ( 36 ) borne by the base ( 6 ).
7 . Set according to claim 4 , characterized in that the base ( 6 ) comprises a peripheral flange ( 30 ) and in that the peripheral contour ( 48 ) of the assembly face ( 40 ) of each shoe ( 8 A, 8 B, 8 C, 8 D) of the set is adapted to be inscribed inside the flange ( 30 ) of the base ( 6 ).
8 . Set according to claim 7 , characterized in that at least corresponding parts of the interior contour of the flange ( 30 ) and of the peripheral contour ( 48 ) of the assembly face ( 40 ) of each shoe ( 8 A, 8 B, 8 C, 8 D) of the set are adapted to cooperate by complementarity of shapes as fixing means ( 44 ).
9 . Set according to claim 1 , characterized in that the articulating surface ( 52 ) of each shoe ( 8 A, 8 B, 8 C, 8 D) of the set presents a third glenoidal cavity ( 64 ) extending along the axis (Y-Y) of the anterior spine ( 56 ) and intended to receive a third condyle of the femoral element ( 2 ).
10 . Process for putting in place a tibial prosthetic assembly ( 4 ) for a knee joint, in which:
a set of prosthetic elements is available, comprising, on the one hand, a base ( 6 ) intended to be connected to the upper end of a tibia and defining a median antero-posterior axis (X-X) and, on the other hand, a plurality of shoes ( 8 A, 8 B, 8 C, 8 D) each adapted to be fixed on the base ( 6 ) and each defining a tibial prosthetic articulating surface ( 52 ) intended to cooperate with a femoral prosthetic element ( 2 ), which articulating surface of each shoe presents both two glenoidal cavities ( 54 , 55 ) for receiving internal ( 14 ) and external ( 15 ) condyles of the femoral element ( 2 ) and an anterior spine ( 56 ) which longitudinally defines an axis (Y-Y), on either side of which these glenoidal cavities are located, the different shoes ( 8 A, 8 B, 8 C, 8 D) of the set being adapted to be mounted on the base ( 6 ) in respective angular positions in each of which the axis (Y-Y) of the anterior spine ( 56 ) of each shoe forms, with the median axis (X-X) of the base, a predetermined angle (α A , α B , α C , α D ) which is possibly zero,
the upper part of a tibia is subjected to resection and there is connected to this resectioned end the base ( 6 ) or a phantom base of the same geometry as the base to be implanted ( 6 ),
a shoe is chosen from the plurality of shoes ( 8 A, 8 B, 8 C, 8 D) of the set, and
the chosen shoe is fixedly mounted on the base ( 6 ), after having, if necessary, replaced the phantom base by the base to be implanted.
11 . Process according to claim 10 , in which, in order to choose the shoe to be mounted from the plurality of shoes ( 8 A, 8 B, 8 C, 8 D) of the set, and after having connected the base ( 6 ) to be implanted or the phantom base on the tibia:
there is mounted on this base a phantom shoe adapted to be retained in mobile manner on the base and defining a tibial prosthetic articulating surface intended to cooperate with the femoral anatomical or prosthetic element ( 2 ), which articulating surface of the phantom shoe presents an anterior spine defining a longitudinal axis,
the knee joint is entrained in at least one movement of flexion-extension,
the residual angular offset between the median axis (X-X) of the base and the longitudinal axis of the anterior spine of the phantom shoe is determined, and
there is chosen, from said shoes ( 8 A, 8 B, 8 C, 8 D) of the set, the shoe whose predetermined angle is substantially equal or the closest to the value of the angular offset determined with the aid of the phantom shoe.