OFFSET STEM TIBIAL IMPLANT

• US 20070179628A1
• Filed: 02/01/2007
• Published: 08/02/2007
• Est. Priority Date: 02/01/2006
• Status: Active Grant

• Current Assignee: Corin Limited (Corin Medical Ltd. /Management/)
• Original Assignee: Tornier Incorporated
• Inventors: Rochetin, Olivier
• Granted Patent: US 7,544,211 B2
• Time in Patent Office: Days
• US Class Current: 623/20.340
• CPC Class Codes: A61F 2/30724 Spacers for centering an implant in a bone cavity, e.g. in a cement-receiving cavity
• CPC Class Codes: A61F 2/3868 with sliding tibial bearing
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2002/30136 undulated or wavy, e.g. serpentine-shaped or zigzag-shaped
• CPC Class Codes: A61F 2002/30329 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2002/30354 Cylindrically-shaped protrusion and recess, e.g. cylinder of circular basis
• CPC Class Codes: A61F 2002/30594 slotted, e.g. radial or meridian slot ending in a polar aperture, non-polar slots, horizontal or arcuate slots
• CPC Class Codes: A61F 2002/30604 modular
• CPC Class Codes: A61F 2002/30878 with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2230/0004 Rounded shapes, e.g. with rounded corners

Abstract

A low-profile offset stem tibial implant includes a tray with a plate that extends transversely around a first tibial axis. The plate includes a distal surface adapted to engage against the prepared surface of the tibia. An engagement portion extends away from the distal surface of the plate substantially along the first tibial axis. A stem is provided with a distal end adapted to be introduced into the medullary canal of the tibia along a second tibial axis and a proximal end. One or more adapter elements are provided with a proximal portion sized to engage with the engagement portion of the plate along the first tibial axis. The adapter element also includes a distal portion adapted to engage with the proximal end of the stem along the second tibial axis. The adapter element permits adjustment of the medio-lateral and antero-posterior position of the second tibial axis relative to the first tibial axis. A plurality of indexing features are located at an interface between the plate and the adapter element to secure the tray in at least three discrete locations around the first tibial axis when in an assembled configuration.

Claims

1. A low-profile offset stem tibial implant for implanting on a prepared surface of a tibia, the tibial implant comprising:

a tray including a plate that extends transversely around a first tibial axis, the plate comprising a distal surface adapted to engage against the prepared surface of the tibia, and an engagement portion extending away from the distal surface of the plate substantially along the first tibial axis;

a stem comprising a distal end adapted to be introduced into the medullary canal of the tibia along a second tibial axis, and a proximal end;

one or more adapter elements comprising a proximal portion sized to engage with and contain substantially all of the engagement portion of the plate along the first tibial axis, and a distal portion adapted to engage with the proximal end of the stem along the second tibial axis, the adapter element permitting adjustment of the medio-lateral and antero-posterior position of the second tibial axis relative to the first tibial axis; and

a plurality of indexing features located at an interface between the plate and the adapter element to secure the tray in at least three discrete locations around the first tibial axis when in an assembled configuration.

2. The tibial implant of claim 1 wherein the engagement portion comprises an annular aperture sized to receive a locking member, the locking member comprising a threaded portion adapted to engage with a complementary threaded portion on the proximal end of the stem.

3. The tibial implant of claim 1 wherein the engagement portion comprises an annular aperture sized to receive the proximal end of the stem.

4. The tibial implant of claim 1 wherein a threaded portion on the proximal end of the stem comprises the primary mechanism to secure the stem, adapter element and tray in the assembled configuration.

5. The tibial implant of claim 1 wherein a threaded portion on the proximal end of the stem comprises the sole fastener securing the stem, adapter element and tray in the assembled configuration.

6. The tibial implant of claim 1 wherein the proximal end of the stem extends above the prepared surface of the tibia when implanted in the medullary canal.

7. The tibial implant of claim 1 wherein the proximal end of the stem extends into the engagement portion of the plate and above the prepared surface of the tibia when implanted in the medullary canal.

8. The tibial implant of claim 1 wherein the tray comprises a generally annular shape centered on the first tibial axis.

9. The tibial implant of claim 1 wherein the plate and the engagement portion comprises an axial dimension of less than about 15 mm.

10. The tibial implant of claim 1 wherein a proximal surface of the plate is perpendicular to the first tibial axis.

11. The tibial implant of claim 1 comprising a pad adapted to engage with a proximal surface of the plate.

12. The tibial implant of claim 1 wherein the proximal end of the stem is located along the second tibial axis.

13. The tibial implant of claim 1 wherein a proximal edge of the adapter element contacts the distal surface of the plate.

14. The tibial implant of claim 1 wherein a proximal edge of the adapter element engages the plate substantially adjacent to the prepared surface of the tibia.

15. The tibial implant of claim 1 wherein a proximal edge of the adapter element engages the distal surface of the plate generally at the prepared surface of the tibia.

16. The tibial implant of claim 1 wherein the engagement portion is substantially nested within the adapter element.

17. The tibial implant of claim 1 wherein the first and second tibial axes are substantially parallel.

18. The tibial implant of claim 1 comprising a plurality of adapter elements, at least two of which comprises different offsets between the first tibial axis and the second tibial axis.

19. The tibial implant of claim 1 comprising first and second adapter elements with different offsets between the first tibial axis and the second tibial axis.

20. The tibial implant of claim 1 wherein the adapter element comprises a proximal aperture with a center axis that is co-linear with a center axis of an aperture extending through the engagement portion on the plate, when in the assembled configuration.

21. The tibial implant of claim 1 wherein the indexing features secure the plate in a multiplicity of locations around the first tibial axis.

22. The tibial implant of claim 1 wherein the indexing features are arranged radially around the first tibial axis.

23. The tibial implant of claim 1 wherein the indexing features are arrange with an angular pitch less than 180°

.

24. The tibial implant of claim 1 wherein the indexing features are arrange with an angular pitch of about 15°

.

25. The tibial implant of claim 1 wherein the indexing features comprise notches distributed regularly along a surface of the engagement portion of the plate.

26. The tibial implant of claim 1 wherein the indexing features comprise ribs formed on the distal surface of the plate.

27. The tibial implant of claim 1 wherein forces produced by an offset at the adapter element between the first and second tibial axes are distributed substantially on, or adjacent to, the prepared surface of the tibia.

28. A low-profile offset stem tibial implant for implanting on a prepared surface of a tibia, the tibial implant comprising:

a tray including a plate that extends transversely around a first tibial axis, the plate comprising a distal surface adapted to engage against the prepared surface of the tibia, and an engagement portion extending away from the distal surface of the plate substantially along the first tibial axis;

a stem comprising a distal end adapted to be introduced into the medullary canal of the tibia along a second tibial axis, and a proximal end;

one or more adapter elements comprising a proximal portion adapted to substantially nest with the engagement portion of the plate along the first tibial axis, and a distal portion adapted to engage with the proximal end of the stem along the second tibial axis, the adapter element permitting adjustment of the medio-lateral and antero-posterior position of the second tibial axis relative to the first tibial axis; and

a plurality of indexing features located at an interface between the plate and the adapter element adapted to secure the tray in at least three discrete locations around the first tibial axis when in an assembled configuration.

29. A low-profile offset stem tibial implant for implanting on a prepared surface of a tibia, the tibial implant comprising:

a tray including a plate that extends transversely around a first tibial axis, the plate comprising a distal surface adapted to engage against the prepared surface of the tibia, and an engagement portion extending away from the distal surface of the plate substantially along the first tibial axis;

a stem comprising a distal end adapted to be introduced into the medullary canal of the tibia along a second tibial axis, and a proximal end;

one or more adapter elements comprising a proximal portion adapted to substantially engaged with the engagement portion of the plate along the first tibial axis, and a distal portion adapted to engage with the proximal end of the stem along the second tibial axis, and the adapter element permitting adjustment of the medio-lateral and antero-posterior position of the second tibial axis relative to the first tibial axis, such that the tibial implant substantially distributes forces produced by an offset between the first and second tibial axes at the adapter element substantially on, or adjacent to, the prepared surface of the tibia; and

a plurality of indexing features located at an interface between the plate and the adapter element adapted to secure the tray in a plurality of discrete locations around the first tibial axis when in an assembled configuration.