Tibial bearing component for a knee prosthesis with improved articular characteristics
An orthopaedic knee prosthesis includes a tibial bearing component with articular features which operate to protect adjacent soft tissues of the natural knee, promote and/or accommodate desired articulation with an abutting femoral component, and facilitate expedient and effective implantation by a surgeon.
1. A family of tibial bearing components for articulation with femoral condyles, each of the family of tibial bearing components defining a tibial bearing component coordinate system comprising:
a bearing component transverse plane extending along a medial/lateral direction and an anterior/posterior direction;
a bearing component coronal plane extending along a proximal/distal direction and the medial/lateral direction, said bearing component coronal plane perpendicular to said bearing component transverse plane; and
a bearing component sagittal plane extending along the anterior/posterior direction and the proximal/distal direction, said bearing component sagittal plane perpendicular to said bearing component transverse plane and said bearing component coronal plane,
said family of tibial bearing components comprising a small tibial bearing component and a large tibial bearing component, said small and large tibial bearing components each comprising:
an articular surface and an opposing distal surface, said distal surface parallel to the bearing component transverse plane, said articular surface including medial and lateral dished articular compartments sized and shaped for articulation with the femoral condyles, said medial and lateral dished articular compartments separated from one another by the bearing component sagittal plane, said articular and distal surfaces bounded by a tibial bearing periphery,
said lateral articular compartment comprising a plurality of coronal cross-sectional profiles defining a lateral set of coronal distal-most points spanning a lateral anterior/posterior extent, said lateral set of coronal distal-most points defining a lateral articular track having an anterior portion and a posterior portion, said anterior portion defining a nominally straight line when projected onto the bearing component transverse plane, said anterior portion of said lateral articular track extrapolated posteriorly to define a lateral intersection point with said tibial bearing periphery,
said medial articular compartment comprising a plurality of coronal cross-sectional profiles defining a medial set of coronal distal-most points spanning a medial anterior/posterior extent, said medial set of coronal distal-most points defining a medial articular track, said medial articular track defining a nominally straight line when projected onto the bearing component transverse plane, said medial articular track extrapolated posteriorly to define a medial intersection point with said tibial bearing periphery,
said lateral and medial intersection points joined by a posterior line, at least one of said lateral articular track and said medial articular track defining an acute angle with said posterior line, the acute angle disposed to a lateral side of the at least one of said lateral articular track and said medial articular track, and
said acute angle of said small tibial bearing component less than said acute angle of said large tibial bearing component.
2. The family of tibial bearing components of claim 1 , wherein said small and large tibial bearing components each comprise a posterior-stabilized design including a spine extending proximally from said articular surface, said spine spaced posteriorly from an anterior edge of said tibial bearing periphery, and said spine disposed between said medial and lateral dished articular compartments,
said acute angle of said small tibial bearing component as little as 81.7 degrees, said acute angle of said large tibial bearing component as large as 86.7 degrees.
3. The family of tibial bearing components of claim 1 , wherein said small and large tibial bearing components each comprise an ultra-congruent design including a posterior eminence extending proximally from said articular surface, wherein for each of said small and large tibial bearing components:
said lateral articular track defining a lateral sagittal distal-most point along said lateral anterior/posterior extent, said posterior eminence defining an eminence height between 8 mm and 10 mm as measured proximally from said lateral sagittal distal-most point,
said posterior eminence extending anteriorly from a posterior edge of said tibial bearing periphery to define an anterior/posterior eminence extent equal to less than 30% of an overall anterior/posterior extent of said tibial bearing component, said posterior eminence disposed between said medial and lateral dished articular compartments,
said acute angle of said small tibial bearing component as little as 82 degrees, said acute angle of said large tibial bearing component as large as 88.7 degrees.
4. The family of tibial components as claim 1 , wherein said small and large tibial bearing components each comprise a cruciate-retaining design comprising:
a posterior cutout sized and positioned to accommodate a posterior cruciate ligament upon implantation of one of the family of tibial bearing components; and
an intercondylar ridge extending anteroposteriorly from said posterior cutout to an anterior relief space proximate an anterior edge of said tibial bearing periphery, said intercondylar ridge disposed between said medial and lateral dished articular compartments,
said acute angle of said small tibial bearing component as little as 81 degrees, said acute angle of said large tibial bearing component as large as 89.5 degrees.
5. The family of tibial bearing components of claim 1 , wherein said small and large tibial bearing components comprise smallest and largest components of a plurality of tibial bearing component sizes, said acute angle trending upward from as little as 81 degrees to as much as 89.5 degrees as tibial bearing component sizes grow larger.
6. The family of tibial bearing components of claim 5 , wherein said plurality of tibial bearing component sizes comprises at least seven bearing component sizes.