Anterior cruciate ligament substituting knee implants

Patent metadata

Field	Value
Publication number	US-9861484-B2
Application number	US-201514793152-A
Country	US
Kind code	B2
Filing date	Jul 7, 2015
Priority date	Apr 13, 2010
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

The present disclosure provides knee prostheses that replicate at least a portion of the function of an individual patient's anterior cruciate ligament (ACL). An exemplary knee prosthesis includes a femoral component configured to be implanted on the distal end of the patient's femur and a tibial component configured to be implanted on the proximal end of the patient's tibia. In extension, the femoral component and the tibial component may cooperate to limit anterior movement of the tibial component relative to the femoral component. In flexion, the femoral component may be free to rotate relative to the tibial component.

First claim

What is claimed is:

1. A knee prosthesis that is configured to articulate between an extended position and a flexed position, the knee prosthesis comprising:
a femoral component including a medial condyle having a medial wall and a lateral condyle having a lateral wall, wherein the medial and lateral walls come to a point and define a triangular shaped opening therebetween; and
a tibial component including:
a medial surface sized to receive the medial condyle of the femoral component;
a lateral surface sized to receive the lateral condyle of the femoral component; and
a central eminence extending proximally from the tibial component and configured to project between the medial and lateral walls, the central eminence having an anterior portion with flat surfaces forming a triangular cross-section that comes to a point and is configured to engage the triangular shaped opening and prevent relative rotation between the tibial and femoral components in the extended position.

2. The knee prosthesis of claim 1 , wherein the central eminence includes:
the anterior portion projecting between the medial and lateral walls in the extended position; and
a posterior portion configured to project between the medial and lateral walls in the flexed position.

3. The knee prosthesis of claim 2 , wherein the anterior portion of the central eminence conforms tightly to the triangular shaped opening in the extended position, and the posterior portion of the central eminence loosely fits between the medial and lateral walls in the flexed position.

4. The knee prosthesis of claim 3 , wherein the posterior portion has a rounded cross-section.

5. The knee prosthesis of claim 4 , wherein the central eminence gradually transitions between the triangular cross-section and the rounded cross-section.

6. The knee prosthesis of claim 3 , wherein the medial and lateral walls are flat.

7. The knee prosthesis of claim 3 , wherein the central eminence has a decreasing height in an anterior to posterior direction.

8. The knee prosthesis of claim 7 , wherein the central eminence flattens in the anterior to posterior direction.

9. The knee prosthesis of claim 3 , wherein the central eminence has a proximal end spaced from the femoral component in both the extended position and the flexed position.

10. The knee prosthesis of claim 3 , wherein the knee prosthesis transitions from the extended position to the flexed position between 10° and 30° of knee flexion, wherein the extended position is more constrained than the flexed position.

11. The knee prosthesis of claim 1 , wherein a radius of curvature of one or both of the medial and lateral condyles decreases in size in an anterior to posterior direction.

12. The knee prosthesis of claim 1 , wherein a width of the medial and lateral condyles decreases in size in an anterior to posterior direction.

13. A knee prosthesis that articulates between an extended position and a flexed position, the extended position defined as including full extension up to 20° of knee flexion, the knee prosthesis comprising:
a femoral component including a medial condyle having an inner medial wall and a lateral condyle having an inner lateral wall, the inner medial and lateral walls being flat to define a triangular shaped opening therebetween; and
a tibial component including:
a medial surface configured for contact with at least a portion of the medial condyle of the femoral component;
a lateral surface configured for contact with at least a portion of the lateral condyle of the femoral component; and
a central eminence extending proximally from the tibial component and projecting between the medial and lateral condyles of the femoral component in both the extended position and the flexed position, the central eminence having less contact with the inner medial and lateral walls when the knee prosthesis is in the flexed position than when the knee prosthesis is in the extended position such that the femoral and tibial components are more constrained, due to contact between the central eminence and the inner medial and lateral walls, against movement relative to each other when the knee prosthesis is in the extended position than when the knee prosthesis is in the flexed position;

wherein the central eminence has an anterior portion including flat surfaces coming to a point and forming a triangular cross-section to engage the triangular shaped opening and prevent relative rotation between the tibial and femoral components in the extended position.

14. The knee prosthesis of claim 13 , wherein a posterior portion of the central eminence has a rounded cross-section, and wherein the central eminence gradually transitions between the triangular cross-section and the rounded cross-section.

15. The knee prosthesis of claim 13 , wherein the central eminence has a decreasing height in an anterior to posterior direction, and wherein the central eminence flattens in the anterior to posterior direction.

16. The knee prosthesis of claim 13 , wherein the central eminence has a proximal end spaced from the femoral component in both the extended position and the flexed position.

17. The knee prosthesis of claim 13 , wherein the movement of the femoral and tibial components relative to each other includes a rotational movement of the femoral component relative to the tibial component about an axis that is medially offset from a center of the knee prosthesis, and the medial and lateral condyles of the femoral component and the medial and lateral surfaces of the tibial component continue to drive rotation of the femoral component relative to the tibial component about the axis as the knee prosthesis articulates from the extended position to the flexed position.

18. The knee prosthesis of claim 13 , wherein the movement of the femoral and tibial components relative to each other includes at least one of:
an anterior movement of the tibial component relative to the femoral component; and
a lateral movement of the femoral component relative to the tibial component; and
whereby the knee prosthesis resists the movement to a greater extent when the knee prosthesis is in the extended position than when the knee prosthesis is in the flexed position.

19. The knee prosthesis of claim 13 , wherein:
the inner medial wall of the medial condyle and the inner lateral wall of the lateral condyle come to a point to define the triangular shaped opening.

Assignees

• Zimmer Inc

Inventors

• Sanford Adam H
• Webster Vincent A
• Todd Dwight T
• Romano Anthony
• Byrd Christopher M
• Claypool Jody L
• Parisi Raymond C

Classifications

• A61F2002/3863

  Condyles fitted on an anchored base · CPC title

• A61F2/38 Primary

  for elbows or knees · CPC title

• A61F2/3859

  Femoral components · CPC title

• A61F2/389

  Tibial components (A61F2/3868 takes precedence) · CPC title

• A61F2/3886

  for stabilising knees against anterior or lateral dislocations · CPC title