Total stabilized knee prosthesis with constraint

• US 7,413,577 B1
• Filed: 09/22/2005
• Issued: 08/19/2008
• Est. Priority Date: 09/22/2005
• Status: Active Grant

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Inventors: Servidio, Damon J.
• Primary Examiner(s): Sweet; Thomas J
• Assistant Examiner(s): Stroud; Jonathan R
• Application Number:
  US11/233,457
• Time in Patent Office: 1,062 Days
• Field of Search: 623/13.12, 623/18.11, 623 2014- 2032
• US Class Current: 623/20.14
• CPC Class Codes: A61F 2/3886 for stabilising knees against anterior or lateral dislocations

Abstract

An improvement in a total stabilized knee prosthesis wherein stabilization against uncontrolled relative rotation between a femoral component and a tibial component about a longitudinal axis, during articulation of the knee prosthesis, is attained by the engagement of a femoral stabilizing compartment with a tibial stabilizing post, the improvement including profile contour configurations on inner surface portions of condylar surfaces and on corresponding outer surface portions of tibial articular surfaces, the profile contour configurations being flared outwardly, in directions away from an intermediate sagittal plane, along posterior aspects of the condylar surfaces and the tibial articular surfaces engaged through deep flexion for providing an engagement between the profile contour configurations sufficient to establish a desired level of constraint against relative rotational movement between the femoral component and the tibial component about the longitudinal axis enabling a decrease in the level of constraint provided by the engagement between the post and the compartment during articulation through deep flexion.

Claims

1. In a total stabilized knee prosthesis for implantation to replace a natural knee joint, the knee prosthesis having a femoral component including at least one condylar element with a condylar surface having a transverse axis of rotation extending transverse to a sagittal plane, and a tibial component including at least one articular surface configured for engagement with the condylar surface of the femoral component during articulation of the knee prosthesis about the transverse axis of rotation, with the condylar surface and the articular surface engaged along corresponding posterior aspects during deep flexion, the condylar surface and the articular surface being configured and dimensioned for enabling engagement between the condylar surface and the articular surface along a prescribed track having a predetermined curvature which enables relative rotational movement between the femoral component and the tibial component about a longitudinal axis of rotation during articulation about the transverse axis of rotation, the condylar surface and the articular surface including profile contour configurations in generally medial-lateral longitudinal planes, the condylar surface having an inner surface portion confronting the longitudinal axis of rotation, and the articular surface having an outer surface portion for engagement with the inner surface portion during articulation, and wherein a level of constraint against uncontrolled relative rotational movement and varus-valgus movements between the femoral component and the tibial component is provided by engagement of a post on one of the femoral component and the tibial component with a compartment in the other of the femoral component and the tibial component:

an improvement wherein the inner surface portion and the outer surface portion are each flared outwardly, in a transverse direction away from the sagittal plane, along the posterior aspects of the condylar surface and the articular surface for providing an engagement between the profile contour configurations sufficient to establish a level of constraint against uncontrolled relative rotational movement between the femoral component and the tibial component about the longitudinal axis, thereby enabling a decrease in the level of constraint provided by the engagement between the post and the compartment during articulation through deep flexion.

2. The improvement of claim 1 wherein the flared surface portions extend along the posterior aspects of the condylar surface and the articular surface from locations corresponding to about 90°

of flexion to locations corresponding to about 150°

of flexion.

3. The improvement of claim 2 wherein the predetermined curvature of the prescribed track includes a first portion extending from a location corresponding to about 0°

of flexion up to a location corresponding to about 90°

of flexion, the first portion being generally arcuate and having a radius extending from a center spaced in a first transverse direction from the sagittal plane.

4. The improvement of claim 3 wherein the predetermined curvature of the prescribed track includes a second portion extending from a location corresponding to about 90°

of flexion to a location corresponding to about 150°

of flexion, the second portion being generally arcuate and having a radius extending from a center spaced in a second transverse direction from the sagittal plane, the second transverse direction being opposite to the first transverse direction.

5. The improvement of claim 1 wherein relative rotation about the longitudinal axis of rotation is enabled up to about 5°

of relative rotation, during flexion up to about 90°

of flexion.

6. The improvement of claim 1 wherein relative rotation about the longitudinal axis of rotation is enabled up to about 5°

of relative rotation, during flexion up to about 150°

of flexion.

7. In a total stabilized knee prosthesis for implantation to replace a natural knee joint, the knee prosthesis having a femoral component including a lateral condylar element and a medial condylar element, each condylar element including a condylar surface having a transverse axis of rotation extending transverse to a sagittal plane, and a tibial component including a lateral articular surface and a medial articular surface, each articular surface being configured for engagement with a corresponding condylar surface of the femoral component during articulation of the knee prosthesis about the transverse axis of rotation, with the condylar surfaces and the articular surfaces engaged along corresponding posterior aspects during deep flexion, each condylar surface and each articular surface being configured and dimensioned for enabling engagement between the condylar surfaces and corresponding articular surfaces along respective prescribed tracks each having a predetermined curvature which enable relative rotational movement between the femoral component and the tibial component about a longitudinal axis of rotation during articulation about the transverse axis of rotation, the condylar surfaces and the articular surfaces including profile contour configurations in generally medial-lateral longitudinal planes, the condylar surfaces each having an inner surface portion confronting the longitudinal axis of rotation and the articular surfaces each having an outer surface portion for engagement with a corresponding inner surface portion during articulation, and wherein a level of constraint against uncontrolled relative rotational movement and varus-valgus movements between the femoral component and the tibial component is provided by engagement of a post on one of the femoral component and the tibial component with a compartment in the other of the femoral component and the tibial component:

an improvement wherein the inner surface portions and the outer surface portions are each flared outwardly, in a transverse direction away from the sagittal plane, along the posterior aspects of the condylar surfaces and articular surfaces for providing an engagement between the profile contour configurations sufficient to establish a level of constraint against uncontrolled relative rotational movement between the femoral component and the tibial component about the longitudinal axis, thereby enabling a decrease in the level of constraint provided by the engagement between the post and the compartment during articulation through deep flexion.

8. The improvement of claim 7 wherein the flared surface portions extend along the posterior aspects of the condylar surfaces and the articular surfaces from locations corresponding to about 90°

of flexion to locations corresponding to about 150°

of flexion.

9. The improvement of claim 8 wherein the predetermined curvature of each prescribed track includes a first portion extending from a location corresponding to about 0°

of flexion up to a location corresponding to about 90°

of flexion, the first portion being generally arcuate and having a radius extending from a center spaced in a first transverse direction from the sagittal plane.

10. The improvement of claim 9 wherein the predetermined curvature of each prescribed track includes a second portion extending from a location corresponding to about 90°

of flexion to a location corresponding to about 150°

of flexion, the second portion being generally arcuate and having a radius extending from a center spaced in a second transverse direction from the sagittal plane, the second transverse direction being opposite to the first transverse direction.

11. The improvement of claim 7 wherein relative rotation about the longitudinal axis of rotation is enabled up to about 5°

of relative rotation, during flexion up to about 90°

of flexion.

12. The improvement of claim 7 wherein relative rotation about the longitudinal axis of rotation is enabled up to about 5°

of relative rotation, during flexion up to about 150°

of flexion.