Posterior stabilized prosthetic knee replacement with bearing translation and dislocation prevention features

• US 20010034554A1
• Filed: 02/28/2001
• Published: 10/25/2001
• Est. Priority Date: 03/08/2000
• Status: Active Grant

• Current Assignee: Biomedical Engineering Trust I
• Original Assignee: Biomedical Engineering Trust I
• Inventors: Pappas, Michael J.
• Granted Patent: US 6,491,726 B2
• Time in Patent Office: Days
• US Class Current: 623/20.29
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/3859 Femoral components
• CPC Class Codes: A61F 2/3868 with sliding tibial bearing
• CPC Class Codes: A61F 2/3886 for stabilising knees against anterior or lateral dislocations
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2002/30332 Conically- or frustoconically-shaped protrusion and recess
• CPC Class Codes: A61F 2002/30339 Double cones, i.e. connecting element having two conical connections, one at each of its opposite ends
• CPC Class Codes: A61F 2002/30364 Rotation about the common longitudinal axis
• CPC Class Codes: A61F 2002/30387 Dovetail connection
• CPC Class Codes: A61F 2002/304 with additional means for limiting said sliding
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30604 modular
• CPC Class Codes: A61F 2002/30823 having the shape of a reverse dovetail
• CPC Class Codes: A61F 2002/30836 knurled
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2220/0041 using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/0088 Coating made of titanium nitride

Abstract

A prosthetic replacement knee joint includes a tibial component, a femoral component, a bearing and a control arm. The tibial component has a superior bearing surface and a conical recess extending into the superior bearing surface. The bearing has an inferior surface slidably engaged with the superior surface of the tibial component and formed with a dovetailed groove therein. The bearing also has a concave superior surface. A notch extends into the posterior extreme of the bearing. The femoral component has a pair of convex arcuate condyles in articular bearing engagement with the superior surface of the bearing. The femoral component also includes a posterior notch having a minor medial-lateral width at the inferior surface of the femoral component and a major width at more superior locations on the femoral component. The control arm has a conical bearing rotatable positioned in the conical recess of the tibial component. The control arm further has a dovetail guide slidably engaged in the dovetail groove of the bearing. A post projects through the notch in the bearing and into the notch of the femoral component. The post has medial and lateral projections that engage portions of the notch in the femoral component that define the major width thereof.

Claims

1. A dislocation resistant knee joint prosthesis comprising:

a femoral component having an inferior articular bearing surface with medial and lateral convex condyles, a posterior notch extending anteriorly into a posterior face of the femoral component, said notch being defined by parallel medial and lateral flanges adjacent the inferior articular bearing surface of the femoral component;

a tibial component;

a bearing disposed between the femoral and tibial components, the bearing having a superior bearing face in articular bearing engagement with the inferior articular bearing surface of the femoral component, the bearing further having an inferior bearing face in sliding and rotational bearing engagement with the tibial component, a posterior notch extending anteriorly into a posterior face of the bearing and a groove formed in the inferior bearing face of the bearing and extending anteriorly from the posterior notch in the bearing; and

a control arm assembly comprising a control arm slidably engaged in the groove of the bearing, the control arm being pivotally mounted on the tibial component, a post extending in a superior direction from the control arm through the posterior notches of the bearing and the femoral component, the post having medial and lateral cam projections engaging superior surfaces of the flanges of the femoral component for generating posterior translation of the bearing during flexion of the knee joint prosthesis and preventing dislocation.

2. The knee joint prosthesis of

claim 1

, wherein said flanges of said femoral component having inferior surfaces substantially conforming to shapes defined by said convex condyles, said superior surfaces of the flanges being arcuately concave superior bearing faces.

3. The knee joint prosthesis of

claim 2

, wherein the medial and lateral cam projections of the post have arcuately convex inferior cam surfaces for bearing engagement against the arcuately concave superior surfaces of the flanges of the femoral component.

4. The knee joint prosthesis of

claim 3

, wherein the femoral component further comprises substantially parallel medial and lateral walls projecting superiorly from the superior surface of the femoral component in proximity to the flanges, the medial and lateral projections of the post having parallel medial and lateral surfaces disposed in sliding engagement with the medial and lateral walls of the femoral component.

5. The knee joint prosthesis of

claim 1

, wherein the tibial component has a superior bearing surface with a recess, the control arm assembly comprising a projection pivotally engaged in the recess of the tibial component for achieving the pivotal mounting of the control arm assembly on the tibial component.

6. The knee joint prosthesis of

claim 5

, wherein the recess in the tibial component and the projection of the control arm assembly have complimentary conical shapes.

7. The knee joint prosthesis of

claim 5

, wherein the superior bearing surface of the tibial component is substantially planar, and wherein the inferior bearing face of the bearing is substantially planar.

8. The knee joint prosthesis of

claim 1

, wherein the groove in the inferior face of the bearing is a dovetail groove, and wherein the control arm has a dovetail configuration for slidable engagement in the groove of the bearing.

9. The knee joint prosthesis of

claim 1

, wherein the superior bearing surface of the bearing comprises medial and lateral concave articular bearing surfaces for articular bearing engagement with the condyles of the femoral component.

10. The knee joint prosthesis of

claim 1

, wherein the femoral component, the tibial component and the control arm are formed from metal, and wherein the bearing and the post are formed from plastic.

11. The knee joint prosthesis of

claim 10

, wherein the control arm assembly comprises a metallic post support pin extending from said control arm and into said plastic post, said metallic post support pin resisting shear forces generated on said post during flexion of said knee joint prosthesis.

12. The knee joint prosthesis of

claim 1

, wherein the flanges of the femoral component are substantially equally spaced from one another at all locations along said notch.

13. The knee joint prosthesis of

claim 1

, wherein the femoral component further comprises an anterior wall extending between the medial and lateral walls and defining a portion of the notch.

14. The knee joint prosthesis of

claim 1

, wherein the bearing is unitarily formed from a UHMWPe.

15. The knee joint prosthesis of

claim 1

, wherein the femoral component and the tibial component both are formed from metallic materials.

16. A dislocation resistant knee joint prosthesis comprising:

a tibial component having a superior bearing surface with a recess therein;

a control arm comprising having an inferior projection rotatably engaged in the recess of the tibial component, a post extending superiorly from the control arm, the post having medial and lateral projections with convex inferior cam surfaces;

a bearing having an inferior surface in sliding bearing engagement with the superior bearing surface of the tibial component, a posterior notch extending anteriorly into a posterior face of the bearing, portions of said post of said control arm inferiorly of the medial and lateral projections being slidably engaged in said posterior notch of said bearing, said bearing further having a groove in the inferior bearing face and extending anteriorly from said notch, the control arm being slidably engaged in the groove; and

a femoral component having an inferior articular bearing surface with medial and lateral convex condyles in articular bearing engagement with the superior bearing face of the bearing, a posterior notch extending anteriorly into a posterior face of the femoral component, said posterior notch being defined by medial and lateral flanges adjacent the inferior articular bearing surface of the femoral component, said flanges having concave superior bearing surfaces engaged with the convex inferior cam surfaces of the projections on the post for generating roll back of the femoral component during flexion of the knee joint prosthesis and preventing dislocation of said femoral component.