# US 2014/0156015 A1 · Motion facilitating tibial components for a knee prosthesis

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- Number: US 2014/0156015 A1
- Document ID: US20140156015A1
- Status: Published application
- Kind: A1
- Application number: 14/034,963
- Filed: 2013-09-24
- Published: 2014-06-05
- Earliest claimed: 2010-09-10
- Assignees: Zimmer, Inc.
- Applicants: Zimmer, Inc.
- Inventors: Raymond C. Parisi; Katherine M. Rettig; Jeff Blaylock
- Web page: https://patentgrep.com/patent/US20140156015A1

## CPC

- A61F 2/389: {Tibial components (A61F2/3868 takes precedence)}
- A61F 2/3886: {for stabilising knees against anterior or lateral dislocations}
- A61F 2/3868: {with sliding tibial bearing}
- A61F 2002/30387: {Dovetail connection}
- A61F 2002/30616: {Sets comprising a plurality of prosthetic parts of different sizes or orientations}
- A61F 2220/0033: made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)

## Abstract

An orthopaedic tibial prosthesis includes a tibial baseplate sized and shaped to cover substantially all of a resected proximal tibial surface, and a tibial bearing component sized to leave a posteromedial portion of the tibial baseplate exposed when the tibial bearing component is mounted to the baseplate. The exposed posteromedial portion of the tibial baseplate includes a chamfered profile which cooperates with a correspondingly chamfered profile at a posteromedial edge of the tibial bearing component to create a substantially continuous chamfer extending from the resected tibial surface to the medial articular surface of the tibial bearing component. Advantageously, this chamfer leaves an absence of material (i.e., a relief or void) at the posteromedial edge of the tibial prosthesis, thereby enabling deep flexion of the prosthesis without impingement between the tibial prosthesis and adjacent anatomic tissues or prosthetic structures.

## Claims

### Claim 1

A tibial bearing component fixable to a tibial baseplate, the tibial bearing component comprising:
a proximal surface defining a lateral articular surface and a medial articular surface;
an anteroposterior axis disposed between the lateral articular surface and the medial articular surface and extending from an anterior edge to a posterior edge of the tibial bearing component;
a bottom portion including a distal surface; and
a peripheral wall disposed between the proximal surface and the distal surface, the peripheral wall including a posterior medial wall extending from the medial articular surface at the posterior edge and a posterior lateral wall extending from the lateral articular surface at the posterior edge, at least one of the posterior medial wall and the posterior lateral wall including a chamfer extending across at least 25% of a proximal/distal height of the peripheral wall, the chamfer forming an acute angle with the distal surface such that the chamfer extends distally and posteriorly from the proximal surface, wherein a medial notch is formed between the posterior medial wall and the bottom portion, and a lateral notch is formed between the posterior lateral wall and the bottom portion, the medial and lateral notches configured for engagement with a tibial baseplate.

### Claim 2 (depends on 1)

The tibial bearing component of claim 1, wherein the chamfer extends in a generally linear direction.

### Claim 3 (depends on 2)

The tibial bearing component of claim 2, wherein a proximal-most point of the chamfer forms a corner with the posterior edge of the proximal surface.

### Claim 4 (depends on 1)

The tibial bearing component of claim 1, wherein the chamfer extends across substantially an entirety of the proximal/distal height of the peripheral wall.

### Claim 5 (depends on 1)

The tibial bearing component of claim 1, wherein the chamfer extends across less than an entirety of the proximal/distal height of the peripheral wall, and a distal portion of the peripheral wall is a vertical portion extending in a direction generally perpendicular to the proximal surface.

### Claim 6 (depends on 1)

The tibial bearing component of claim 1, wherein the chamfer defines an arcuate profile in a sagittal plane.

### Claim 7 (depends on 1)

The tibial bearing component of claim 1, wherein the acute angle of the chamfer comprises an angle between about 35 degrees and about 75 degrees.

### Claim 8 (depends on 7)

The tibial bearing component of claim 7, wherein the acute angle comprises an angle of about 61 degrees.

### Claim 9 (depends on 1)

The tibial bearing component of claim 1, in combination with a tibial baseplate comprising:
a baseplate distal surface configured for contacting a bone surface;
an opposing baseplate proximal surface defining a medial compartment and a lateral compartment;
a baseplate anteroposterior axis disposed between the medial compartment and the lateral compartment, the anteroposterior axis extending from an anterior edge to a posterior edge of the tibial baseplate; and
a raised surface extending around at least a portion of a periphery of the baseplate proximal surface, wherein a portion of the raised surface is configured to be received by each of the medial notch and the lateral notch of the tibial bearing component when the bearing component is fixed to the tibial baseplate.

### Claim 10

A tibial bearing component fixable to a tibial baseplate, the tibial bearing component fi comprising:
a proximal surface defining a lateral articular surface and a medial articular surface;
an opposing distal surface;
an anteroposterior axis disposed between the lateral articular surface and the medial articular surface and extending from an anterior edge to a posterior edge of the tibial bearing component; and
a peripheral wall disposed between the proximal surface and the distal surface, the peripheral wall including a posterior medial wall extending from the medial articular surface at the posterior edge and a posterior lateral wall extending from the lateral articular surface at the posterior edge, at least one of the posterior medial wall and the posterior lateral wall including a chamfer extending across at least 25% of a proximal/distal height of the peripheral wall, the chamfer forming an acute angle with the distal surface such that the chamfer extends distally and posteriorly from the proximal surface in a generally linear direction, wherein a proximal-most point of the chamfer forms a corner with the posterior edge of the proximal surface.

### Claim 11 (depends on 10)

The tibial bearing component of claim 10, wherein the chamfer defines a first portion of the peripheral wall, and a second portion of the peripheral wall extends in a generally linear direction generally perpendicular to the proximal surface.

### Claim 12 (depends on 10)

The tibial bearing component of claim 10, wherein the chamfer extends across at least 50% of the proximal/distal height of the peripheral wall.

### Claim 13 (depends on 10)

The tibial bearing component of claim 10, wherein the chamfer extends across substantially an entirety of the proximal/distal height of the peripheral wall.

### Claim 14 (depends on 10)

The tibial bearing component of claim 10, wherein the acute angle comprises an angle between about 35 degrees and about 75 degrees.

### Claim 15

A tibial prosthesis comprising:
a tibial baseplate comprising:
a baseplate distal surface configured for contacting a bone surface;
an opposing baseplate proximal surface defining a medial compartment and a lateral compartment;
a baseplate anteroposterior axis disposed between the medial compartment and the lateral compartment, the anteroposterior axis extending from an anterior edge to a posterior edge of the tibial baseplate;
a baseplate peripheral wall disposed between the baseplate distal surface and the baseplate proximal surface; and
a raised surface extending around at least a portion of a periphery of the baseplate proximal surface, a proximal-posterior medial edge formed between the baseplate peripheral wall and the raised surface at the posterior edge in the medial compartment; and
a tibial bearing component fixable to the tibial baseplate and comprising:
a bearing distal surface;
an opposing bearing proximal surface defining a lateral articular surface and a medial articular surface;
a bearing anteroposterior axis disposed between the lateral articular surface and the medial articular surface and extending from an anterior edge to a posterior edge of the tibial bearing component; and
a bearing peripheral wall disposed between the bearing proximal surface and the bearing distal surface, the bearing peripheral wall having a medial chamfer extending distally and posteriorly from the bearing proximal surface at the posterior edge of the medial articular surface, the medial chamfer extending across at least 25% of a proximal/distal height of the bearing peripheral wall and forming an acute angle with the bearing distal surface, a distal-posterior medial edge of the bearing peripheral wall formed at a distal-most point of the bearing peripheral wall, wherein the distal-posterior medial edge of the bearing peripheral wall is aligned with the proximal-posterior medial edge of the tibial baseplate when the tibial bearing component is fixed to the tibial baseplate.

### Claim 16 (depends on 15)

The tibial prosthesis of claim 15, wherein the tibial bearing component further comprises a posterior notch formed between a peripheral distal surface of the bearing peripheral wall and the bearing distal surface at a posterior end, the notch configured for engagement with the raised surface of the tibial baseplate.

### Claim 17 (depends on 15)

The tibial prosthesis of claim 15, wherein the tibial bearing component further comprises an anterior notch at an anterior end for engagement with the raised surface of the tibial baseplate.

### Claim 18 (depends on 15)

The tibial prosthesis of claim 15, wherein the medial chamfer of the tibial bearing component extends across substantially an entirety of the proximal/distal height of the peripheral wall.

### Claim 19 (depends on 15)

The tibial prosthesis of claim 15, wherein the medial chamfer of the tibial bearing component extends across less than an entirety of the proximal/distal height of the bearing peripheral wall, and a distal portion of the bearing peripheral wall is a vertical portion extending in a direction generally perpendicular to the bearing proximal surface.

### Claim 20 (depends on 15)

The tibial prosthesis of claim 15, wherein the acute angle of the medial chamfer comprises an angle between about 35 degrees and about 75 degrees.

### Claim 21 (depends on 15)

The tibial prosthesis of claim 15, wherein the baseplate peripheral wall of the tibial baseplate includes a baseplate chamfer extending from a posterior portion of the medial compartment towards the baseplate distal surface.

### Claim 22 (depends on 21)

The tibial prosthesis of claim 21, wherein the baseplate chamfer defines an acute baseplate chamfer angle with the baseplate distal surface, the baseplate chamfer angle substantially the same as the acute angle of the medial chamfer of the tibial bearing component.