Modular knee prosthesis
View Patent ↗A joint prosthesis may include a tibial tray, a tibial base, a tibial articular member, and a femoral articular member. In some embodiments, a coupler engages the tray, and optionally the base, with an interference fit. In some embodiments, the base engages the tray with an interference fit.
1. A joint prosthesis comprising a tibial tray, a tibial base, a coupler, a tibial articular member, and a femoral articular member, wherein:
the tibial tray, the tibial base, the coupler and the tibial articular member define a common axis;
the tibial tray comprises a stem protruding distally from a proximal surface, the proximal surface:
sized and shaped to cover at least part of a cut proximal end of a tibia; and
defining a bore therethrough;
the tibial base comprises:
a distal surface sized and shaped to interface with the proximal surface of the tibial tray; and
a proximal surface sized and shaped to attach to the tibial articular member;
the coupler comprises:
a proximal portion that contacts the tibial base, holds the distal surface of the tibial base in contact with the proximal surface of the tibial tray, and permits rotation of the tibial base about the common axis with respect to the tibial tray; and
a distal portion that is received in the tibial tray bore with a diametrical interference fit;
the tibial articular member comprises:
a distal surface so sized and shaped as to attach to the proximal surface of the tibial base and to permit the tibial articular member to rotate about the common axis with the tibial base; and
a proximal surface sized and shaped to articulate with the femoral articular member; and
the femoral articular member comprises:
a distal surface sized and shaped to articulate with the proximal surface of the tibial articular member; and
a proximal surface sized and shaped to replace at least part of a cut proximal end of a femur.
2. The joint prosthesis of claim 1 , wherein the coupler comprises a shoulder that so engages a lip on the tibial base as to prevent disassociation of the tibial base from the tibial tray.
3. The joint prosthesis of claim 1 , wherein the tibial tray stem, the tibial base, and the tibial articulating member each defines a bore aligned with the tibial tray proximal surface bore.
4. The joint prosthesis of claim 1 , wherein the distal portion of the coupler that participates in the interference fit with the tibial tray bore has a constant cross-sectional geometry along its length.
5. The joint prosthesis of claim 4 , wherein the distal portion of the coupler that participates in the interference fit with the tibial tray bore is cylindrical or substantially cylindrical along its length.
6. The joint prosthesis of claim 5 , wherein the distal portion of the coupler that participates in the interference fit with the tibial tray bore is cylindrical along its length.
7. The joint prosthesis of claim 1 , wherein the interference fit is an interference press-fit.
8. The joint prosthesis of claim 1 , wherein the tibial tray comprises metal, and the tibial base comprises metal.
9. A joint prosthesis comprising a tibial tray, a tibial base, a tibial articular member, and a femoral articular member, wherein:
the tibial tray comprises a proximal surface and a stem protruding distally from the proximal surface, the proximal surface being sized and shaped such that when the stem is seated in a medullary canal of a tibia from which a proximal portion has been removed, the proximal surface would cover at least part of a cut proximal end of the tibia;
the tibial base comprises:
a distal portion having a mating surface with a constant non tapering cross-sectional geometry along its length that engages the tibial tray with an interference press-fit; and
a proximal surface sized and shaped to attach to the tibial articular member;
the tibial articular member comprises a single piece that includes:
a distal surface so sized and shaped as to attach to the proximal surface of the tibial base; and
a proximal surface sized and shaped to articulate with the femoral articular member; and
the femoral articular member comprises:
a distal surface sized and shaped to articulate with the proximal surface of the tibial articular member; and
a proximal surface sized and shaped to replace at least part of a cut proximal end of a femur.
10. The joint prosthesis of claim 9 , wherein the proximal surface of the tibial tray defines a bore, and the distal portion of the tibial base comprises a protrusion that is received in the tibial tray bore to form the interference press-fit.
11. The joint prosthesis of claim 9 , wherein the distal portion of the tibial base defines a bore, and the proximal surface of the tibial tray comprises a protrusion that is received in the tibial base bore to form the interference press-fit.
12. A joint prosthesis comprising a tibial tray, a tibial base, a coupler, a tibial articular member, and a femoral articular member, wherein:
the tibial tray comprises a proximal surface and a stem protruding distally from the proximal surface, the proximal surface defining a bore therethrough, the proximal surface being sized and shaped such that when the stem is seated in a medullary canal of a tibia from which a proximal portion has been removed, the proximal surface would cover at least part of a cut proximal end of the tibia;
the tibial base comprises:
a distal surface sized and shaped to interface with the proximal surface of the tibial tray; and
a proximal surface sized and shaped to attach to the tibial articular member;
the coupler comprises:
a proximal portion that engages the tibial base with a diametrical interference fit; and
a distal portion that engages the tibial tray bore with a diametrical interference fit;
the tibial articular member comprises:
a distal surface so sized and shaped as to attach to the proximal surface of the tibial base; and
a proximal surface sized and shaped to articulate with the femoral articular member; and
the femoral articular member comprises:
a distal surface sized and shaped to articulate with the proximal surface of the tibial articular member; and
a proximal surface sized and shaped to replace at least part of a cut proximal end of a femur.
13. The joint prosthesis of claim 12 , wherein the coupler comprises a shoulder that engages a lip on the tibial base to hold the distal surface of the tibial base to the proximal surface of the tibial tray.
14. The joint prosthesis of claim 12 , wherein the tibial tray stem, the tibial base, and the tibial articulating member each defines a bore aligned with the tibial tray proximal surface bore.
15. The joint prosthesis of claim 12 , wherein the distal portion of the coupler that participates in the interference fit with the tibial tray has a constant cross-sectional geometry.
16. The joint prosthesis of claim 15 , wherein the distal portion of the coupler that participates in the interference fit with the tibial tray is cylindrical or substantially cylindrical.
17. The joint prosthesis of claim 16 , wherein the distal portion of the coupler that participates in the interference fit with the tibial tray bore is cylindrical.
18. The joint prosthesis of claim 12 , wherein the proximal portion of the coupler that participates in the interference fit with the tibial base has a constant cross-sectional geometry.
19. The joint prosthesis of claim 18 , wherein the proximal portion of the coupler that participates in the interference fit with the tibial base is cylindrical or substantially cylindrical.
20. The joint prosthesis of claim 19 , wherein the proximal portion of the coupler that participates in the interference fit with the tibial base bore is cylindrical.
21. The joint prosthesis of claim 20 , wherein the distal portion of the coupler that participates in the interference fit with the tibial tray bore is cylindrical.
22. The joint prosthesis of claim 18 , wherein the distal portion of the coupler that participates in the interference fit with the tibial tray has a constant cross-sectional geometry.
23. The joint prosthesis of claim 12 , wherein the interference fits are interference press-fits.
24. The joint prosthesis of claim 12 , wherein the tibial tray comprises metal, and the tibial base comprises metal.