Modular knee joint prosthesis

• US 5,370,699 A
• Filed: 01/21/1993
• Issued: 12/06/1994
• Est. Priority Date: 01/21/1993
• Status: Expired due to Term

• Current Assignee: Wright Medical Technology Incorporated (Stryker Corporation)
• Original Assignee: Orthomet, Inc. (Stryker Corporation)
• Inventors: Carter, Robert D., Hood, Roger W., Samson, Serafin Y.
• Primary Examiner(s): ISABELLA, DAVID J
• Application Number:
  US08/007,161
• Time in Patent Office: 684 Days
• Field of Search: 623/16, 623/18, 623/20
• US Class Current: 623/20.28
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• CPC Class Codes: A61F 2/3886 for stabilising knees against anterior or lateral dislocations
• CPC Class Codes: A61F 2002/30387 Dovetail connection
• CPC Class Codes: A61F 2002/305 Snap connection
• CPC Class Codes: A61F 2002/30604 modular
• CPC Class Codes: A61F 2002/30772 Apertures or holes, e.g. of circular cross section
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2310/00029 Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium

Abstract

An implantable knee joint prosthesis which comprises a tibial tray, an articulating tibial insert attached to the tibial tray, and a femoral condylar component adapted to cooperatively bear upon the tibial insert. The femoral component has an intercondylar recess having parallel lateral side walls and posterior and anterior bearing members defining the boundaries of the recess. The tibial insert includes an eminence extending superiorly into the intercondylar recess and dimensioned and shaped to provide defined stabilization limits for preventing posterior-anterior dislocation while allowing limited translation and essentially free rotation and angulation throughout most of the total range of articulation. Metal reinforcements serve to secure the insert to the tray. Bearing surfaces of the eminence and the intercondylar recess are so shaped as to increase the area of contact between them as the degree of flexion of the leg increases to thereby limit the contact stress transmitted to the eminence and to reduce wear of the eminence.

Claims

1. A knee joint prosthesis comprising:

a femoral component adapted to be implanted on the condylar portion of the femur and having a pair of laterally spaced-apart condylar portions having smooth external surfaces that are convexly curved in the antero-posterior direction and generally match the shapes in lateral profile of the condylar surfaces of the femur and that are smoothly convexly curved in all cross sections along their antero-posterior extents, and an intercondylar portion interconnecting the condylar portions and defining an intercondylar recess having lateral side walls spaced-apart a predetermined distance, an anterior stop surface and a posterior camming member; and

a tibial component adapted to be implanted on the tibial plateau and including a substantially flat platform portion having a superior surface bearing a pair of laterally spaced-apart concavities adapted to receive in nested relation the respective condylar portions of the femoral component, and an eminence extending superiorly from the platform portion and generally between the concavities, the eminence being adapted to be received in the intercondylar recess of the femoral component, the eminence having lateral surfaces, an anterior surface and a posterior surface, the relative positions and shapes of the anterior and posterior surfaces of the eminence and recess of the prosthesis as implanted in the knee joint being such as to permit relatively free antero-posterior translation of the components while restraining excessive anterior and posterior movements, and wherein the eminence includes lateral surfaces having portions essentially parallel to the lateral side walls of the recess defining a width of the eminence substantially narrower than the distance between the spaced-apart lateral side walls and portions angled with respect to anterior-posterior planes for enabling medial/lateral translation and substantial varus/valgus angulation and relative rotation between the tibial component and the femoral component throughout a substantial portion of the range of flexion.

2. A knee joint prosthesis comprising:

a femoral component adapted to be implanted on the condylar portion of the femur and having a pair of laterally spaced-apart condylar portions, and an intercondylar portion interconnecting the condylar portions and defining an intercondylar recess having lateral side walls spaced-apart a predetermined distance, an anterior stop surface and a posterior camming member; and

a tibial component comprising a tibial insert of plastic material fitted and held in a tibial tray adapted to be attached to the resected tibia, the tibial insert having a superior aspect comprising spaced-apart concavities and a tibial eminence therebetween and receivable in the intercondylar recess of the femoral component, and attachment means for attachment of the tibial insert to the tibial tray, the attachment means comprising a pair of dovetail-shaped bosses extending in parallel on the superior surface of the tibial tray and a recess extending perpendicularly to the bosses, and a like dimensioned pair of dovetail-shaped grooves formed in the inferior surface of the plastic tibial insert and a boss extending perpendicularly to the grooves, the boss on the insert having reinforcing metal inserts extending from the surface of the boss into the insert, the eminence being adapted to be received in the intercondylar recess of the femoral component, the eminence having lateral surfaces, an anterior surface and a posterior surface, the relative positions and shapes of the anterior and posterior surfaces of the eminence and recess of the prosthesis as implanted in the knee joint being such as to permit relatively free antero-posterior translation of the components while restraining excessive anterior and posterior movements, and wherein the eminence includes lateral surfaces having portions essentially parallel to the lateral side walls of the recess defining a width of the eminence substantially narrower than the distance between the spaced-apart lateral side walls and portions angled with respect to anterior-posterior planes for enabling medial/lateral translation and substantial varus/valgus angulation and relative rotation between the tibial component and the femoral component throughout a substantial portion of the range of flexion.

11. The knee joint prosthesis of claim 2 wherein the tibial insert further comprises metal reinforcing means inserted in the plastic for cooperative relationship with the dovetail-shaped bosses of the tibial tray when the dovetail-shaped grooves are fitted thereon.

3. In a knee joint prosthesis of the type comprising:

a femoral component adapted to be implanted on the condylar portion of the femur and having a pair of laterally spaced-apart condylar portions having external surfaces that are smoothly convexly curved in the antero-posterior direction and generally match the shapes in lateral profile of the condylar surfaces of the femur and that are smoothly convexly curved in all cross sections along its antero-posterior extent; and

a tibial component adapted to be implanted on the tibial plateau and including a substantially flat, non-metallic, tibial insert attached to a metal tibial tray, the insert having a superior surface bearing a pair of laterally spaced-apart concavities adapted to receive in nested relation the respective condylar portions of the femoral component, wherein the tibial insert is attached to the tibial tray by an attachment mechanism comprising interfitting dovetail-shaped bosses and grooves carried on mating surfaces of the tray and insert, respectively, the bosses containing imbedded metal reinforcing elements for making contact with the metal tibial tray and reinforcing the tibial insert from separating from the tibial tray.

4. The knee joint prosthesis of claim 3 wherein the attachment means of the tibial tray comprises a pair of dovetail-shaped bosses extending in parallel on the superior surface of the tibial tray and a recess extending perpendicularly to the bosses, and wherein the attachment means of the tibial insert comprises a like dimensioned pair of dovetail-shaped grooves formed in the inferior surface of the plastic tibial insert and a boss extending perpendicularly to the grooves, wherein the bosses on the insert is reinforced by metal inserts extending from the surface of the boss into the insert.

5. The knee joint prosthesis of claim 4 wherein the tibial insert further comprises metal reinforcing means inserted in the plastic for cooperative relationship with the dovetail-shaped bosses of the tibial tray when the dovetail-shaped grooves are fitted thereon.

6. A knee joint prosthesis comprising:

a femoral component adapted to be implanted on the condylar portion of the femur and having a pair of laterally spaced-apart condylar portions and an intercondylar portion interconnecting the condylar portions and defining an intercondylar recess having lateral side walls and a posterior bearing surface; and

a tibial component adapted to be implanted on the tibial plateau and including a substantially flat platform portion having on its superior surface a pair of laterally spaced-apart concavities adapted to receive in nested relation the respective condylar portions of the femoral component, and an eminence extending superiorly from the platform portion and generally between the concavities for reception in the intercondylar recess of the femoral component, the eminence having lateral surfaces, an anterior surface and a posterior bearing surface, the relative positions and shapes of the anterior and posterior surfaces of the eminence and recess of the prosthesis as implanted in the knee joint being such as to permit relatively free relative antero-posterior translation of the components while restraining excessive anterior and posterior movements between the components, and wherein the respective posterior bearing surfaces of the tibial component and the femoral component are shaped so that as flexion of the knee increases, the force-transmitting contact area between such bearing surfaces increases.

7. The knee joint prosthesis of claim 6 wherein the tibial eminence includes lateral surfaces having portions that are essentially parallel to the lateral side walls of the recess and that define a width of the eminence substantially narrower than the distance between the spaced-apart lateral side walls of the intercondylar recess, the tibial eminence also having surface portions angled with respect to anterior-posterior planes for enabling medial/lateral translation and substantial varus/valgus angulation and relative rotation between the tibial component and the femoral component within a substantial portion of the range of flexion.

8. The knee joint prosthesis of claim 6 wherein said tibial component comprises a tibial insert of a plastic material fitted and held in a tibial tray adapted to be attached to the resected tibia, the tibial insert having a superior aspect comprising the spaced-apart concavities and the eminence therebetween and an inferior aspect having attachment means for attachment to the tibial tray, wherein the attachment means comprises metal reinforcing means fitted within the plastic material for making metal-to-metal attaching contact with the tibial tray.

9. The knee joint prosthesis of claim 8 wherein the attachment means comprises a pair of dovetail-shaped bosses extending in parallel on the superior surface of the tibial tray and a recess extending perpendicularly to the bosses, and wherein the tibial insert is provided with a like dimensioned pair of dovetail-shaped grooves formed in the inferior surface of the plastic tibial insert and a boss extending perpendicularly to the grooves, wherein the boss on the insert is reinforced by metal inserts extending from the surface of the boss into the insert.

10. The knee joint prosthesis of claim 9 wherein the tibial insert further comprises metal reinforcing means inserted in the plastic for cooperative relationship with the dovetail-shaped bosses of the tibial tray when the dovetail-shaped grooves are fitted thereon.

12. A knee joint prosthesis comprising:

a femoral component adapted to be implanted on the condylar portion of the femur and having a pair of laterally spaced-apart condylar portions, and an intercondylar portion interconnecting the condylar portions and defining an intercondylar recess having lateral side walls spaced apart a predetermined distance, an anterior stop surface and a posterior camming member; and

a tibial component comprising a tibial insert of plastic material fitted and held in a tibial tray adapted to be attached to the resected tibia, the tibial insert having a superior aspect comprising spaced-apart concavities for articulation with the condylar portions of the femoral component and a tibial eminence therebetween and receivable in the intercondylar recess of the femoral component, the eminence having lateral surfaces, an anterior surface and a posterior surface, the relative positions and shapes of the anterior and posterior surfaces of the eminence and recess of the prosthesis as implanted in the knee joint being such as to permit relatively free antero-posterior translation of the components while restraining excessive anterior and posterior movements, and wherein the eminence includes lateral surfaces having portions defining a width of the eminence substantially narrower than the distance between the spaced-apart lateral side walls and portions angled with respect to anterior-posterior planes for enabling medial/lateral translation and substantial varus/valgus angulation and relative rotation between the tibial component and the femoral component throughout a substantial portion of the range of flexion, the respective posterior bearing surfaces of the tibial component and the femoral component being so shaped that as flexion of the knee increases, the force-transmitting contact area between such bearing surfaces increases.