Asymmetric tibial components for a knee prosthesis

Patent metadata

Field	Value
Publication number	US-9192480-B2
Application number	US-201314034944-A
Country	US
Kind code	B2
Filing date	Sep 24, 2013
Priority date	Jul 24, 2010
Publication date	Nov 24, 2015
Grant date	Nov 24, 2015

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 family of tibial prostheses sized for attachment to a proximal tibia, the family comprising:
a plurality of tibial prostheses defining a plurality of prosthesis peripheries, each said prosthesis periphery defining:
a centroid,
an anteroposterior axis dividing said prosthesis periphery into a medial compartment and a lateral compartment;
a posterior-medial distance extending from said centroid to a posterior-medial corner of said prosthesis periphery;

a posterior-lateral distance extending from said centroid to a posterior-lateral corner of said prosthesis periphery;
said plurality of prosthesis peripheries including:
a small periphery corresponding to a small prosthesis size, said small periphery defining said posterior-medial distance having a small posterior-medial extent and said posterior- lateral distance having a small posterior-lateral extent;
a medium periphery corresponding to a medium prosthesis size that is the next- largest consecutive prosthesis size as compared to said small prosthesis size, said medium periphery defining said posterior-medial distance having a medium posterior-medial extent larger than said small posterior-medial extent to exhibit a first posterior-medial growth, said medium periphery further defining said posterior-lateral distance having a medium posterior-lateral extent larger than said small posterior-lateral extent to exhibit a first posterior-lateral growth; and
a large periphery corresponding to a large prosthesis size that is the next-largest consecutive prosthesis size as compared to said medium prosthesis size, said large periphery defining said posterior-medial distance having a large posterior-medial extent larger than said medium posterior-medial extent to exhibit a second posterior-medial growth, said large periphery further defining said posterior-lateral distance having a large posterior-lateral extent larger than said medium posterior-lateral extent to exhibit a second posterior-lateral growth,

said second posterior-medial growth larger than said first posterior-medial growth, and
said second posterior-lateral growth larger than said first posterior-lateral growth,
whereby said plurality of tibial prostheses exhibit non-linear, asymmetric growth in medial and lateral posterior corners of said prosthesis peripheries as sizes of said tibial prostheses consecutively increase,
wherein said plurality of tibial prostheses comprises a plurality of tibial baseplates, in combination with a plurality of tibial bearing components, each of said plurality of tibial bearing components comprising:
a lateral portion which substantially corresponds to said prosthesis periphery for said lateral compartment of one of said plurality of tibial prostheses, and
a medial portion which is at least partially incongruent with said prosthesis periphery for said medial compartment of one of said plurality of tibial prostheses.

2. The family of tibial prostheses of claim 1 , wherein:
said first posterior-medial growth is larger than said first posterior-lateral growth, whereby said medial compartment grows faster than said lateral compartment in said medium periphery as compared to said small periphery.

3. The family of tibial prostheses of claim 1 , wherein:
said second posterior-medial growth is larger than said second posterior-lateral growth, whereby said medial compartment grows faster than said lateral compartment in said large periphery as compared to said medium periphery.

4. The family of tibial prostheses of claim 1 , wherein said second posterior-medial growth is about 20% larger than said first posterior-medial growth and said second posterior-lateral growth is about 4% larger than said first posterior-lateral growth.

5. The family of tibial prostheses of claim 1 , wherein said plurality of tibial prostheses comprises at least seven tibial prostheses, each of said tibial prostheses consecutively larger,
each of said tibial prostheses defining a respective posterior-medial growth larger than a posterior-medial growth of a next consecutive smaller posterior-medial growth, and
each of said tibial prostheses defining a respective posterior-lateral growth larger than a posterior-lateral growth of the next consecutive smaller posterior-medial growth.

6. The family of tibial prostheses of claim 1 , wherein:
each of said plurality of tibial baseplates includes a posteromedial baseplate chamfer in said medial compartment;
each of said plurality of tibial bearing components includes a posteromedial bearing chamfer formed thereon in said medial portion; and
each of said plurality of tibial bearing components adapted to mount to a respective one of said plurality of tibial baseplates to form a respective tibial prosthesis assembly, said baseplate chamfer and said bearing chamfer cooperating to form a substantially continuous chamfer in said tibial prosthesis assembly.

7. The family of tibial prostheses of claim 1 , in combination with at least one femoral component adapted to articulate with at least one of said plurality of tibial bearing components through a range of flexion.

8. The family of tibial prostheses of claim 1 , wherein said anteroposterior axis is aligned with a home axis when said a respective tibial prosthesis is mounted to a tibia, said home axis defined as a line extending from
a posterior point at a geometric center of an attachment area between a posterior cruciate ligament and the tibia, to
an anterior point disposed on an anterior tubercle of the tibia, the tubercle having a tubercle width W, said anterior point disposed on the tubercle at a location medially spaced from a midpoint of the tubercle by an amount equal to W/6.

9. A family of tibial prostheses sized for attachment to a proximal tibia, the family comprising:
a plurality of tibial prostheses defining a plurality of prosthesis peripheries, each said prosthesis periphery defining:
a centroid,
an anteroposterior axis dividing said prosthesis periphery into a medial compartment and a lateral compartment;
a posterior-medial distance extending from said centroid to a posterior-medial corner of said prosthesis periphery;
a posterior-lateral distance extending from said centroid to a posterior-lateral corner of said prosthesis periphery;

said plurality of prosthesis peripheries including:
a small periphery defining said posterior-medial distance having a small posterior- medial extent and said posterior-lateral distance having a small posterior-lateral extent; and
a large periphery defining said posterior-medial distance having a large posterior- medial extent larger than said small posterior-medial extent to exhibit a posterior-medial growth, said large periphery further defining said posterior-lateral distance having a large posterior-lateral extent larger than said small posterior-lateral extent to exhibit a posterior-lateral growth,

said posterior-medial growth larger than said posterior-lateral growth,
whereby said medial compartment grows faster than said lateral compartment in said large periphery as compared to said small periphery,
wherein said plurality of tibial prostheses comprises a plurality of tibial baseplates, in combination with a plurality of tibial bearing components,
each of said plurality of tibial baseplates includes a posteromedial baseplate chamfer in said medial compartment,
each of said plurality of tibial bearing components includes a posteromedial bearing chamfer formed thereon in said medial portion, and
each of said plurality of tibial bearing components adapted to mount to a respective one of said plurality of tibial baseplates to form a respective tibial prosthesis assembly, said baseplate chamfer and said bearing chamfer cooperating to

Assignees

• Zimmer Inc

Inventors

• Wentorf Mary S S
• Bischoff Jeffrey E

Classifications

• A61F2002/30301

  saddle-shaped · CPC title

• A61F2/3868

  with sliding tibial bearing · CPC title

• A61F2002/30616

  Sets comprising a plurality of prosthetic parts of different sizes or orientations · 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