Tibia part of a new joint endoprosthesis

• US 6,258,127 B1
• Filed: 07/23/1999
• Issued: 07/10/2001
• Est. Priority Date: 09/11/1996
• Status: Expired due to Term

• Current Assignee: Smith & Nephew Orthopaedics Ag (Smith & Nephew PLC)
• Original Assignee: Plus Endoprothetik AG (Smith & Nephew PLC)
• Inventors: Schmotzer, Hans
• Primary Examiner(s): Philogene, Pedro
• Application Number:
  US09/254,853
• Time in Patent Office: 718 Days
• Field of Search: 623/20, 623/16, 623/18, 623/19, 623/23, 623/22, 623/20.14, 623/20.15, 623/20.16, 623/20.21, 623/20.22, 623/20.23, 623/20.27, 623/20.32, 623/20.33, 623/20.34
• US Class Current: 623/20.32
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence

Abstract

A tibia part of a knee joint prosthesis includes a tibia platform having a distal side, and an anchoring element. The anchoring element is arranged on the distal side of the tibia platform and attached to the tibia platform. In one embodiment, the anchoring element is formed by a shield having a height which is smaller than a width of the shield, and the shield has a U-, C- or V-shape as seen from the tibia platform.

Claims

1. A tibia part of a knee joint prosthesis, comprising:

a tibia platform having a distal side; and

an anchoring element arranged on the distal side of the tibia platform and attached to the tibia platform, the anchoring element formed by a shield having a height which is smaller than a width of the shield, the shield having an upper surface facing the distal side of the tibia platform, a shape selected from a group consisting of a U-shape, C-shape and V-shape, and a distal edge which is convexly arc-shaped, an arc line of the distal edge defining a section selected from the group consisting of a circular section, an elliptical section, and a parabola.

2. The tibia part of claim 1, further comprising a central web positioned in an area in which the height of the shield is maximal, the central web bisecting the shield into a lateral portion and a medial portion.

3. The tibia part of claim 2, wherein the central web extends over the entire height of the shield.

4. The tibia part of claim 1, wherein the shield has at least two proximally accessible threaded borings at the upper surface, the threaded borings receiving screws extending through corresponding borings in the tibia platform to secure the tibia platform to the shield.

5. The tibia part of claim 4, wherein the shield has three threaded borings.

6. The tibia part of claim 4, wherein the threaded borings are placed centrally on the lateral portion and the medial portion of the anchoring shield.

7. The tibia part of claim 1, wherein a distal edge of the shield is designed as a cutting edge.

8. The tibia part of claim 1, wherein the anchoring shield is connected to the distal side of the tibia platform along the upper surface and without play.

9. The tibia part of claim 1, further comprising a recess on the distal side of the tibia platform, the recess configured to receive a proximal front side of the shield without play.

10. The tibia part of claim 1, wherein a shield surface is roughened or structured.

11. The tibia part of claim 1, wherein the distal side of the tibia platform comprises projections which are arranged at a spacing from one another sufficient to encourage growth of bone onto the tibia platform.

12. The tibia part of claim 11, wherein the projections have a shape selected from a group consisting of ribs, cutting edges, pegs, needles, and cylinders.

13. The tibia part of claim 11, wherein the projections on the distal side of the tibia platform have a spacing of approximately 3-6 mm.

14. The tibia part of claim 11, wherein the projections have a spacing of approximately 4-5 mm.

15. The tibia part of claim 10, wherein the shield surface has a structure that has at least one of a longitudinal and transverse orientation.

16. The tibia part of claim 15, wherein the shield surface comprises teeth which have at least one of a longitudinal and transverse orientation.

17. A tibia part of a knee joint prosthesis, comprising:

a tibia platform having a distal side; and

an anchoring element arranged on the distal side of the tibia platform and attached to the tibia platform, the anchoring element formed by a shield having a height which is smaller than a width of the shield, the shield having a proximal edge facing the distal side of the tibia platform, said shield having a distal edge configured for insertion into bone, wherein said shield decreases in thickness in a stepwise manner from said proximal edge to said distal edge such that opposing wall surfaces of the shield remain parallel at each step.

18. A method of installing a knee joint prosthesis, said prosthesis comprising a tibia platform and an anchoring element, said method comprising:

inserting said anchoring element into a proximal portion of a tibia bone until an upper surface of said anchoring element is sunk beneath the tibia bone surface; and

securing said tibia part to said anchoring element.

19. The method of claim 18, wherein said anchoring element comprises a shield having a height which is less than a width of said shield.