Modular hinge knee prosthesis and improvements of same

Patent metadata

Field	Value
Publication number	US-10548735-B2
Application number	US-201514820151-A
Country	US
Kind code	B2
Filing date	Aug 6, 2015
Priority date	Aug 6, 2015
Publication date	Feb 4, 2020
Grant date	Feb 4, 2020

Abstract

A total knee prosthesis including a tibial component having a baseplate portion and a protruding portion extending from the baseplate portion is disclosed. An axle is connectable to the tibial component directly or indirectly. A femoral component has an articular surface and an opening for receipt of the axle. The opening defines a pivot center about which the femoral prosthesis rotates. The articular surface has a posterior portion having a first flexion radius defining a first flexion center. The first flexion center is offset from the pivot center a distance substantially equal to a product of a constant and the first flexion radius.

First claim

The invention claimed is:

1. A total knee prosthesis, comprising:
a tibial component having a baseplate portion and a protruding portion extending from the baseplate portion;
an axle connectable to the tibial component; and
a femoral component having an articular surface and an opening for receipt of the axle, the opening defining a pivot center about which the femoral prosthesis rotates with respect to the tibial component, the articular surface having anterior and posterior portions, the posterior and anterior portions each being curved so as to define respective first and second flexion centers, the first flexion center being offset from the posterior portion by a first flexion radius, the second flexion center being offset from the anterior portion by a second flexion radius,
wherein the first flexion center is positioned relative to the pivot center and to the second flexion center so that when the total knee prosthesis is implanted, a patella articulating with the articular surface of the femoral component has a maximum patellar tilt angle of about 35 degrees when the total knee prosthesis is articulated between 90 and 135 degrees of flexion.

2. The total knee prosthesis of claim 1 , wherein the first flexion center is offset from the pivot center a distance equal to a product of the first flexion radius and a constant that is equal to 0.4.

3. The total knee prosthesis of claim 1 , wherein the femoral component has an anterior-posterior dimension defined by a distance between anterior and posterior extents of the prosthesis, and the first flexion radius is equal to one-third of the anterior-posterior dimension.

4. The total knee prosthesis of claim 1 , wherein the first flexion radius is about 16-28 mm.

5. The total knee prosthesis of claim 1 , wherein the protruding portion of the tibial component defines a longitudinal axis, and the pivot center is about 15-25 mm from the longitudinal axis in an anterior-posterior direction when the tibial component and femoral component are coupled together via the axle.

6. The total knee prosthesis of claim 5 , wherein the baseplate portion includes a bone contact surface for contacting a proximal tibial resected surface, the bone contact surface being about 35-55 mm from the pivot center in a superior-inferior direction when the tibial component and femoral component are coupled together via the axle.

7. The total knee prosthesis of claim 1 , wherein the first flexion center is positioned such that a line segment intersecting the pivot center and first flexion center is substantially parallel to a patella tendon when the total knee prosthesis is implanted and articulated to about 90 degrees of flexion.

8. The total knee prosthesis of claim 1 , wherein the articular surface includes an anterior portion having a second flexion radius defining a second flexion surface.

9. The total knee prosthesis of claim 8 , wherein the first flexion center is about 7-21 mm offset in the sagittal plane from the second flexion center.

10. The total knee prosthesis of claim 8 , wherein the pivot center, first flexion center, and second flexion center form vertices of a triangle having a hypotenuse extending between the pivot center and second flexion center, a first line segment extending between the pivot center and first flexion center, and a second line segment extending between the first and second flexion centers.

11. The total knee prosthesis of claim 10 , wherein an angle formed between the first line segment and hypotenuse is about 15-60 degrees.

12. The total knee prosthesis of claim 10 , wherein the hypotenuse is about 15-35 mm.

13. The total knee prosthesis of claim 10 , wherein, when the total knee prosthesis is implanted into a knee joint comprised of a femur and a tibia and articulated beyond 90 degrees of flexion, a reference angle formed between the first line segment and a line intersecting the pivot center and a tibial tubercle of the tibia determines a patellar tilt angle of a patella about the tibial tubercle with respect to a superior-inferior axis of the tibia.

14. The total knee prosthesis of claim 13 , wherein the reference angle and patellar tilt angle are substantially equal.

15. The total knee prosthesis of claim 14 , wherein the reference angle is about 35 degrees or less.

16. The total knee prosthesis of claim 1 , further comprising a coupling component having a bearing, a head portion, and an articulating portion, the bearing being receivable by the tibial component, the head portion engageable to the femoral component and having an opening extending therethrough for receipt of the axle, the articulating portion disposed between the head portion and bearing and having a curved inferior surface for sliding articulation with a superior surface of the tibial component.

17. A total knee prosthesis comprising:
a tibial component for implantation into a tibia of a knee joint;
a coupling component configured to engage the tibial component and having a head portion defining an opening therethrough for receipt of an axle; and
a femoral component for implantation into a femur of a knee joint defining a recess for receipt of the head portion and a transverse opening for receipt of the axle and having an articular surface having a first curved portion and a second curved portion, the opening defining a pivot center about which the femoral component flexes and extends, the first curved portion defining a first radius and a first center, the second curved portion defining a second radius and a second center,
wherein the pivot center and first and second centers are positioned with respect to each other such that when the total knee prosthesis is implanted into the knee joint, the articular surface is positioned with respect to a tibial tubercle of the tibia such that a tilt angle of a patella about the tibial tubercle achieves and maintains about 35 degrees or less with respect to a superior-inferior axis of the tibia as the patella articulates with the articular surface through flexion of the femoral component relative to the tibial component of between 90 and 135 degrees.

18. The total knee prosthesis of claim 17 , wherein the first center is offset from the pivot center in a sagittal plane a distance equal to a product of a constant and the first radius, the constant being 0.4 and the first radius being about 16-28 mm.

19. The total knee prosthesis of claim 18 , wherein the first radius is equal to one-third of an anterior-posterior dimension of the formal component that extends between anterior and posterior extents of the femoral component.

20. The total knee prosthesis of claim 18 , wherein the second center is offset from the pivot center in a sagittal plane a distance substantially equal to 15-35 mm.

21. The total knee prosthesis of claim 20 , wherein the first center and second center are offset from one another a distance substantially equal to 7-21 mm.

22. A total knee prosthesis, comprising:
a tibial component having a baseplate portion and a protruding portion extending from the baseplate portion;
an axle connectable to the tibial component; and
a femoral component having an articular surface and an opening for receipt of the axle, the opening defining a pivot center about which the femoral prosthesis rotates, the articular surface having a posterior portion having a first flexion radius defining a first flexion center, the first flexion radius being equal to one-third of an anterior-posterior width of the femoral component.

Assignees

• Howmedica Osteonics Corp

Inventors

• Servidio Damon J

Classifications

• A61F2002/30632

  with rotation-limiting stops, e.g. projections or recesses · CPC title

• A61F2002/30331

  made by longitudinally pushing a protrusion into a complementarily-shaped recess, e.g. held by friction fit · CPC title

• A61F2002/30474

  using an intermediate sleeve interposed between both prosthetic parts to be coupled · CPC title

• A61F2002/30624

  Hinged joint, e.g. with transverse axle restricting the movement · CPC title

• A61F2/3845 Primary

  allowing only for single rotation · CPC title