Total knee replacement implant based on normal anatomy and kinematics

Patent metadata

Field	Value
Publication number	US-11071631-B2
Application number	US-201815909749-A
Country	US
Kind code	B2
Filing date	Mar 1, 2018
Priority date	Oct 12, 2010
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

A total knee replacement prosthesis is presented whose bearing surfaces are derived from an anatomically representative femur and a modified baseline tibial surface. The contacting femoral and tibial bearing surfaces include the inter-condylar as well as condylar regions. A knee replacement implant includes a femoral component and a tibial component. The femoral component includes an outer femoral bearing surface shaped to match an outer bearing surface of an anatomic femur. The tibial component includes a proximal tibial bearing surface based on a proximal baseline tibial bearing surface that is shaped to conform to an envelope of a composite of sequence of positions and orientations of the femoral component throughout a full range of flexure angles and axial rotation angles of the femur relative to the tibia.

First claim

What is claimed is:

1. A knee replacement implant comprising:
a femoral component having an outer femoral bearing surface, wherein the femoral component is configured for attachment with a distal end of a femur, and wherein the outer femoral bearing surface is shaped to match an outer bearing surface of an anatomic femur; and
a tibial component comprising a proximal tibial bearing surface, wherein the tibial component is configured for attachment with a tibia at a proximal end of the tibia, wherein each point on the proximal tibial bearing surface has a respective height above a transverse reference plane that passes through a most distal point of the proximal tibial bearing surface, wherein each respective height is equal to a baseline height of a corresponding point on a proximal baseline tibial bearing surface above the transverse reference plane scaled by a constant scaling factor in a range from 0.8 to 0.9, wherein the proximal baseline tibial bearing surface is shaped to conform to an envelope of a composite of sequence of positions and orientations of the femoral component throughout a full range of flexure angles and axial rotation angles of the femur relative to the tibia.

2. The knee replacement implant of claim 1 , wherein the proximal tibial bearing surface comprises greater dishing in a central region of a proximal-medial portion of the proximal tibial bearing surface compared to dishing in a central region of a proximal-lateral portion of the proximal tibial bearing surface.

3. The knee replacement implant of claim 1 , wherein the proximal tibial bearing surface comprises a medial bearing surface with dishing in a central region that allows for only 2-4 mm of anterior-posterior displacement between the femoral component and the tibial component.

4. The knee replacement implant of claim 1 , wherein the outer femoral bearing surface comprises a medial condylar region, a lateral condylar region, and an intercondylar region.

5. The knee replacement implant of claim 4 , wherein each of the medial condylar region, the lateral condylar region and the intercondylar region is defined by coronal cross-sections, wherein each of the coronal cross-sections corresponds to a respective position and orientation of the femoral component relative to the tibial component, wherein each of the coronal cross-sections comprises a convex medial condylar segment that tangentially and smoothly transitions into a concave intercondylar segment that tangentially and smoothly transitions into a convex lateral condylar segment, wherein each of the concave intercondylar segments have an intercondylar outer surface and an intercondylar proximal surface, and wherein the intercondylar outer surface and the intercondylar proximal surface are separated by a constant distance in each of the coronal cross-sections.

6. The knee replacement implant of claim 5 , wherein the constant distance is between 2 mm to 4 mm.

7. The knee replacement implant of claim 5 , wherein an intercondylar housing height of the coronal cross-sections is 16 mm at 0 degrees flexion, 19 mm at 45 degrees flexion, and 19 mm at 90 degrees flexion.

8. The knee replacement implant of claim 5 , wherein an intercondylar sidewall angle in each of the coronal cross-sections is between 55 and 75 degrees relative to the transverse reference plane.

9. The knee replacement implant of claim 5 , wherein each of the concave intercondylar segments has an intercondylar radius between 6 mm and 10 mm.

10. The knee replacement implant of claim 1 , wherein the proximal tibial bearing surface comprises a posterior-medial portion that is in conformity with the outer femoral bearing surface and adjacent bone at a maximum angle of flexure.

11. The knee replacement implant of claim 1 , wherein the proximal tibial bearing surface comprises a lateral bearing surface that has a substantially flat region in a center of a sagittal section.

12. The knee replacement implant of claim 1 , wherein the proximal tibial bearing surface comprises a posterior central region that contacts the femoral component at flexion after 90 degrees, and wherein the femoral component and the tibial component are in continuous contact extending from a lateral condylar region to a medial condylar region at flexion after 90 degrees.

13. The knee replacement implant of claim 1 , wherein the proximal tibial bearing surface comprises an anterior central region that contacts the femoral component at 3-6 degrees of hyperextension.

14. The knee replacement implant of claim 1 , wherein the proximal tibial bearing surface of the tibial component has a relieved posterior surface that provides a femoral-tibial contact location at a center of the tibial component when the femoral component is at an upper flexion limit of the full range of flexure angles.

15. A knee replacement implant comprising:
a femoral component comprising a femoral bearing surface, wherein the femoral bearing surface comprises a medial condylar region, a lateral condylar region, and an intercondylar region, wherein each of the medial condylar region, the lateral condylar region and the intercondylar region is defined by coronal cross-sections, wherein each of the coronal cross-sections corresponds to a respective position and orientation of the femoral component, wherein each of the coronal cross-sections comprises a convex medial condylar segment that tangentially and smoothly transitions into a concave intercondylar segment that tangentially and smoothly transitions into a convex lateral condylar segment, and wherein an intercondylar housing height is 14-18 mm in a coronal cross-section at 0 degrees flexion and 17-21 mm in coronal cross-sections at 45 degrees and 90 degrees flexion; and
a tibial component comprising a proximal tibial bearing surface, wherein the tibial component is configured for attachment with a tibia at a proximal end of the tibia, wherein each point on the proximal tibial bearing surface has a respective height above a transverse reference plane that passes through a most distal point of the proximal tibial bearing surface, wherein each respective height is equal to a baseline height of a corresponding point on a proximal baseline tibial bearing surface above the transverse reference plane scaled by a constant scaling factor in a range from 0.8 to 0.9, wherein the proximal baseline tibial bearing surface is shaped to conform to an envelope of a composite of sequence of positions and orientations of the femoral component throughout a full range of flexure angles and axial rotation angles of the femur relative to the tibia.

16. The knee replacement implant of claim 15 , wherein each of the concave intercondylar segments has an intercondylar radius between 6 mm and 10 mm.

17. The knee replacement implant of claim 15 , wherein each of the intercondylar segments has an intercondylar outer surface and an intercondylar proximal surface, and wherein the intercondylar outer surface and the intercondylar proximal surface is uniform are separated by a constant distance in each of coronal cross-sections.

18. The knee replacement implant of claim 17 , wherein the constant distance is between 2 mm to 4 mm.

19. The knee replacement implant of claim 15 , wherein an intercondylar sidewall angle in each of the coronal cross-sections is between 55 and 75 degrees relative to the transverse reference plane.

20. A knee replacement implant comprising:
a femoral component comprising an outer femoral bearing surface, wherein the femoral component is configured for attachment with a fe

Assignees

• Univ New York

Inventors

• Walker Peter Stanley

Classifications

• A61F2002/30952

  using CAD-CAM techniques or NC-techniques · CPC title

• A61F2/38 Primary

  for elbows or knees · CPC title

• A61F2002/30948

  using computerized tomography, i.e. CT scans · CPC title

• A61F2/3886

  for stabilising knees against anterior or lateral dislocations · CPC title