Asymmetric tibial components for a knee prosthesis

Patent metadata

Field	Value
Publication number	US-9295557-B2
Application number	US-201314034954-A
Country	US
Kind code	B2
Filing date	Sep 24, 2013
Priority date	Jul 24, 2010
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

An orthopaedic tibial prosthesis includes a tibial baseplate with an asymmetric periphery which promotes proper positioning and orientation on a resected tibia, while also facilitating enhanced kinematics, soft-tissue interaction, and long-term fixation of the complete knee prosthesis. The asymmetric baseplate periphery is sized and shaped to substantially match portions of the periphery of a typical resected proximal tibial surface, such that proper location and orientation is evident by resting the baseplate on the tibia. The baseplate periphery provides strategically positioned relief and/or clearance between the baseplate periphery and bone periphery, such as in the posterior-medial portion to prevent deep-flexion component impingement, and in the anterior-lateral portion to avoid undue interaction between the anatomic iliotibial band and prosthesis components.

First claim

What is claimed is:

1. A method of implanting a tibial prosthesis on a tibia, the method comprising:
resecting a proximal end of a tibia to create a resected tibial surface, the tibia having an anteriorly disposed tibial tubercle and a connection point to a posterior cruciate ligament;
identifying an anatomic anteroposterior axis which intersects:
an anterior point disposed on the tubercle, the anterior point medially spaced from a tubercle midpoint by an amount equal to ⅙ th of an overall mediolateral width of the tubercle such that the anterior point lies on the medial third of the tubercle; and
a posterior point disposed at a geometric center of an area defined by the connection point of the tibia to the posterior cruciate ligament;

providing a tibial prosthesis having alignment indicia indicating a component anteroposterior axis designed to be aligned with the anatomic anteroposterior axis, wherein the tibial prosthesis comprises a tibial baseplate having a distal surface comprising a bone contacting surface and a proximal surface comprising a tibial bearing engagement surface, the tibial prosthesis having a lateral compartment and a medial compartment, the lateral compartment is asymmetric with respect to the medial compartment about the component anteroposterior axis to define a component asymmetry; and
positioning and orienting the tibial prosthesis with respect to the tibia by aligning the alignment indicia with the anatomic anteroposterior axis, the step of positioning comprising matching the component asymmetry to a corresponding asymmetry of the resected tibial surface, whereby the tibial prosthesis covers a large proportion of the resected tibial surface.

2. The method of claim 1 , wherein:
said step of providing comprises providing a tibial prosthesis including:
an anterior edge; and
a PCL cutout area generally opposite said anterior edge and disposed between a lateral compartment of the tibial prosthesis and a medial compartment of the tibial prosthesis,

said component anteroposterior axis bisecting the anterior edge and bisecting the PCL cutout area,
whereby said step of positioning comprises centering the anterior edge with respect to the anterior point disposed on the tubercle, and centering the PCL cutout area with respect to the connection point of the tibia to the posterior cruciate ligament.

3. The method of claim 2 , wherein:
the medial compartment cooperates with the component anteroposterior axis to bound a medial surface area,
the lateral compartment cooperates with the component anteroposterior axis to bound a lateral surface area,
the medial surface area larger than the lateral surface area.

4. The method of claim 3 , wherein the medial surface area occupies between about 52% and about 53% of the medial and lateral surface areas combined.

5. The method of claim 1 , wherein:
said step of providing comprises having the lateral compartment and the medial compartment cooperate to define a peripheral wall, the peripheral wall including:
an anterior edge;
a lateral posterior edge generally opposite the anterior edge and forming a posterior boundary of the lateral compartment;
a medial posterior edge generally opposite the anterior edge and forming a posterior boundary of the medial compartment;
a lateral periphery extending from the anterior edge to the lateral posterior edge; and
a medial periphery extending from the anterior edge to the medial posterior edge.

6. The method of claim 5 , wherein the component asymmetry comprises a surface area asymmetry, in which:
the medial periphery cooperates with the component anteroposterior axis to bound a medial surface area;
the lateral periphery cooperates with the component anteroposterior axis to bound a lateral surface area; and
the medial surface area larger than the lateral surface area,
said step of positioning comprising:
matching the larger medial surface area to a corresponding medial portion of the resected tibial surface, and
matching the smaller lateral surface area to a corresponding lateral portion of the resected tibial surface.

7. The method of claim 6 , wherein the medial surface area occupies between about 52% and about 54% of the medial and lateral surface areas combined.

8. The method of claim 5 , wherein said step of positioning includes covering between about 60% and about 90% of the tibia to create a buffer zone on all sides between the resected tibial surface and the peripheral wall.

9. The method of claim 5 , wherein the component asymmetry comprises an anteroposterior extent asymmetry, in which:
the lateral compartment defines a lateral anteroposterior extent extending from the anterior edge of the peripheral wall to the lateral posterior edge thereof; and
the medial compartment defines a medial anteroposterior extent extending from the anterior edge of the peripheral wall to the medial posterior edge thereof,
the medial anteroposterior extent larger than the lateral anteroposterior extent,
said step of positioning comprising:
matching the larger medial anteroposterior extent to a corresponding medial portion of the resected tibial surface, and
matching the smaller lateral anteroposterior extent to a corresponding lateral portion of the resected tibial surface.

10. The method of claim 5 , wherein the component asymmetry comprises an anteroposterior corner asymmetry, in which:
an anterior-medial corner of the medial periphery defines an anterior-medial corner radius, and
an anterior-lateral corner of the lateral periphery defines an anterior-lateral corner radius that is substantially smaller than the anterior-medial corner radius,
said step of positioning comprising:
matching the smaller anterior-lateral corner radius to a corresponding lateral portion of the resected tibial surface, and
matching the larger anterior-medial radius to a corresponding medial portion of the resected tibial surface.

11. The method of claim 5 , wherein the component asymmetry comprises a medial-lateral asymmetry, in which:
the lateral periphery defines a plurality of adjacent lateral arcs, an adjacent pair of the plurality of adjacent lateral arcs defining a first lateral radius and a second lateral radius, respectively, the first lateral radius larger than said second lateral radius by at least 100%, whereby said lateral periphery is relatively boxy,
said step of positioning comprising matching the boxy lateral periphery to a correspondingly boxy lateral portion of the resected tibial surface.

12. The method of claim 5 , wherein the component asymmetry comprises a medial-lateral asymmetry, in which:
the medial periphery defines a plurality of adjacent medial arcs, a pair of the plurality of adjacent medial arcs defining a first medial radius and a second medial radius, respectively, the first medial radius larger than the second medial radius by less than 75%, whereby said medial periphery is generally rounded,
said step of positioning comprising matching the rounded medial periphery to a correspondingly rounded medial portion of the resected tibial surface.

13. The method of claim 5 , wherein the tibial prosthesis comprises a tibial baseplate, the method further comprising providing a tibial bearing component comprising:
a lateral bearing portion which substantially corresponds to the lateral periphery of the tibial prosthesis; and
a medial bearing portion which is at least partially incongruent with the medial periphery of the tibial prosthesis.

14. The method of claim 13 , further comprising mounting the tibial bearing component to the tibial baseplate such that the medial bearing portion is ante

Assignees

• Zimmer Inc

Inventors

• Wentorf Mary S S
• Bischoff Jeffrey E
• Sanford Adam H
• Hodorek Robert

Classifications

• A61F2002/30301

  saddle-shaped · CPC title

• A61F2002/30883

  dovetail-shaped · CPC title

• A61F2220/0025

  Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements · CPC title

• A61F2/389 Primary

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

• A61F2/3868

  with sliding tibial bearing · CPC title