Total knee replacement implant based on normal anatomy and kinematics

Patent metadata

Field	Value
Publication number	US-9931215-B2
Application number	US-201113877541-A
Country	US
Kind code	B2
Filing date	Oct 11, 2011
Priority date	Oct 12, 2010
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

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. The modified baseline tibial surface is generated by modifying a baseline tibial surface. For example, the baseline tibial surface can be flattened mathematically to generate the modified baseline tibial surface.

First claim

What is claimed:

1. A knee replacement implant comprising:
a tibial component comprising a proximal tibial bearing surface; and
a femoral component comprising an outer femoral bearing surface, said outer femoral bearing surface configured to engage said proximal tibial bearing surface and rotate relative to said proximal tibial bearing surface through a full range of flexure angles;
wherein said outer femoral bearing surface comprises a medial condylar region, a lateral condylar region, and an intercondylar region;
wherein said proximal tibial bearing surface is structured such that said proximal tibial bearing surface is formed from a baseline tibial bearing surface when each point of said proximal tibial bearing surface is scaled by a constant scaling factor greater than one relative to a transverse reference plane, wherein said transverse reference plane includes a most distal point of said proximal tibial bearing surface, and said baseline tibial bearing surface is defined as a composite of multiple outer femoral bearing surfaces positioned, with respect to said tibial component, throughout said range of flexure angles including in full extension and full flexion.

2. 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.

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 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 the lateral condylar region to the medial condylar region at flexion after 90 degrees.

5. 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.

6. 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.

7. The knee replacement implant, in accordance with claim 1 , wherein:
each of said medial condylar, lateral condylar and intercondylar regions defined by a plurality of coronal cross-sections, each coronal cross-section corresponding to one of a succession of angles of flexure of said femoral component, wherein each of said plurality of coronal cross-sections comprise a convex medial condylar segment, tangentially and smoothly transitioning into a concave intercondylar segment, tangentially and smoothly transitioning into a convex lateral condylar segment, each of said intercondylar segments in the plurality of coronal cross-sections having the same intercondylar radius, each of said intercondylar segments in the plurality of coronal cross-sections having an intercondylar outer surface and an intercondylar proximal surface, a thickness between said intercondylar outer surface and said intercondylar proximal surface is uniform in each of the plurality of coronal cross-sections.

8. The knee replacement implant, in accordance with claim 7 , wherein said thickness is 2 mm to 4 mm in each of the plurality of coronal cross-sections.

9. The knee replacement implant, in accordance with claim 7 , wherein said proximal tibial bearing surface comprises a posterior-medial portion that is in conformity with said outer femoral bearing surface and adjacent bone at a maximum angle of flexure.

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

11. The knee replacement implant, in accordance with claim 7 , wherein an intercondylar sidewall angle in each of the plurality of coronal cross-sections is between 55 and 75 degrees relative to said transverse reference plane.

12. The knee replacement implant, in accordance with claim 7 , wherein said intercondylar radius in each of the plurality of coronal cross-sections is between 6 mm and 10 mm.

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

Assignees

• Walker Peter S
• Univ New York

Inventors

• Walker Peter Stanley

Classifications

• A61F2/3886

  for stabilising knees against anterior or lateral dislocations · CPC title

• A61F2/38 Primary

  for elbows or knees · CPC title

• A61F2002/30952

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

• A61F2002/30948

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