阅读说明：本技术 具有内侧枢转股骨部件和插入物的整形外科系统 (Orthopaedic system with medial pivoting femoral component and insert ) 是由 S·E·怀特 W·J·马隆尼 于 2020-03-11 设计创作，主要内容包括：一种整形外科系统包括胫骨插入物和股骨部件,该股骨部件被构造成在胫骨插入物上进行关节运动。胫骨插入物包括关节表面,并且股骨部件包括具有向后减小的曲率半径的股骨关节表面。胫骨插入物的关节表面包括增加的前唇缘以改善股骨部件的稳定性。(An orthopaedic system includes a tibial insert and a femoral component configured to articulate on the tibial insert. The tibial insert includes an articular surface and the femoral component includes a femoral articular surface having a posteriorly decreasing radius of curvature. The articular surface of the tibial insert includes an increased anterior lip to improve the stability of the femoral component.)

1. An orthopedic system comprising:

a tibial insert having a medial articular surface and a lateral articular surface, wherein the medial articular surface and the lateral articular surface are asymmetrically shaped relative to each other; and

a femoral component having a medial condyle configured to articulate on the medial articular surface of the tibial insert and a lateral condyle configured to articulate on the lateral articular surface of the tibial insert, wherein the medial condyle of the femoral component includes a femoral articular surface having a first radius of curvature extending posteriorly to a first degree of flexion of 70 degrees or less and a plurality of decreasing radii of curvature extending posteriorly from the first degree of flexion to a second degree of flexion greater than the first degree of flexion.

2. The orthopaedic system of claim 1, wherein the femoral articular surface of the femoral component has a second radius of curvature at the second degree of flexion, the second radius of curvature being greater than each of the reduced radii of curvature.

3. The orthopaedic system of claim 1, wherein the femoral articular surface of the femoral component has a second radius of curvature posterior to the reduced radius of curvature, the second radius of curvature being greater than a last radius of the plurality of reduced radii of curvature.

4. The orthopedic system according to claim 1, wherein the medial articular surface of the tibial insert and the femoral articular surface of the medial condyle of the femoral component are more conformal than the lateral articular surface of the tibial insert and the femoral articular surface of the lateral condyle of the femoral component.

5. The orthopedic system according to claim 4, wherein the medial articular surface of the tibial insert and the femoral articular surface of the medial condyle have an anterior-posterior conformity of at least 96% at zero degrees of flexion.

6. The orthopedic system according to claim 4, wherein the medial articular surface of the tibial insert and the femoral articular surface of the medial condyle have a medial-lateral conformity of at least 93%.

7. The orthopedic system according to claim 6, wherein the lateral articular surface of the tibial insert and the femoral articular surface of the lateral condyle have a medial-lateral conformity of at least 93%.

8. The orthopedic system according to claim 1, wherein the tibial insert includes an antero-medial lip having a first height and an antero-lateral lip having a second height, and wherein the first height of the antero-medial lip is greater than the second height of the antero-lateral lip.

9. The orthopedic system according to claim 8, wherein the medial articular surface of the tibial insert includes a dwell point, and the first height of the anterior-medial lip relative to the dwell point is at least 9 millimeters.

10. The orthopedic system according to claim 8, wherein the medial articular surface of the tibial insert includes a dwell point having an arcuate or elliptical shape when viewed in a transverse plane.

11. The orthopedic system according to claim 1, wherein the medial articular surface of the tibial insert includes a dwell point and an antero-medial lip, wherein the antero-medial lip has a height relative to the dwell point of at least 9 millimeters.

12. The orthopedic system according to claim 1, wherein the medial articular surface of the tibial insert includes a dwell point having an arcuate or elliptical shape when viewed in a transverse plane.

13. The orthopedic system according to claim 1, wherein the first radius of curvature has a length between 41% to 47% of an anterior-posterior length of the tibial insert.

14. The orthopedic system according to claim 1, wherein the medial articular surface of the tibial insert includes a dwell point and the lateral articular surface provides an arcuate path for pivoting the femoral component about the dwell point.

15. The orthopedic system according to claim 1, wherein the first radius of curvature extends forward to an over-flexion degree of 30 degrees or less.

16. A tibial insert for a knee replacement system, the tibial insert comprising:

a lateral articular surface configured to articulate with a lateral condyle of a femoral component; and

a medial articular surface configured to articulate with a medial condyle of the femoral component, wherein the medial articular surface is asymmetrically shaped relative to the lateral articular surface and includes a dwell point and an anterior-medial lip having a height relative to the dwell point of at least nine millimeters.

17. The tibial insert of claim 16, wherein the medial articular surface and the medial condyle of the femoral component are more conformal than the lateral articular surface and the lateral condyle of the femoral component.

18. The tibial insert of claim 16, wherein the dwell point has an arcuate or elliptical shape when viewed in the transverse plane.

19. The tibial insert of claim 16, wherein the lateral articular surface comprises an antero-lateral lip having a height that is less than a height of the antero-lateral lip.

20. An orthopedic system comprising:

a tibial insert comprising a lateral articular surface and a medial articular surface, an

A femoral component including a medial condyle configured to articulate on the medial articular surface of the tibial insert and a lateral condyle configured to articulate on the lateral articular surface of the tibial insert, the medial condyle of the femoral component including a femoral articular surface having a first radius of curvature extending posteriorly to a first degree of flexion of 70 degrees or less and a plurality of decreasing radii of curvature extending posteriorly from the first degree of flexion to a second degree of flexion greater than the first degree of flexion,

wherein the medial articular surface of the tibial insert is asymmetrically shaped relative to the lateral articular surface and includes a dwell point having an arcuate or elliptical shape when viewed in the transverse plane and an antero-medial lip having a height relative to the dwell point of at least nine millimeters.

21. The orthopedic system according to claim 20, wherein the tibial insert includes an antero-lateral lip, and wherein the height of the antero-lateral lip is greater than the height of the antero-lateral lip.

22. The orthopaedic system of claim 20, wherein the femoral articular surface of the femoral component has a second radius of curvature at the second degree of flexion, wherein the second radius of curvature is greater than a last radius of the plurality of reduced radii of curvature.

23. The orthopedic system according to claim 22, wherein the second radius of curvature is posterior to the reduced radius of curvature.

24. The orthopedic system according to claim 20, wherein the medial articular surface of the tibial insert and the femoral articular surface of the medial condyle of the femoral component are more conformal than the lateral articular surface of the tibial insert and the femoral articular surface of the lateral condyle of the femoral component.

25. The orthopedic system according to claim 24, wherein the medial articular surface of the tibial insert and the femoral articular surface of the medial condyle have a medial-lateral conformity of at least 93%.

26. The orthopedic system according to claim 20, wherein the lateral articular surface provides an arcuate path for pivoting the femoral component about the dwell point.

27. The orthopedic system according to claim 20, wherein the first radius of curvature extends forward to an over-flexion degree of 30 degrees or less.

28. An orthopedic system comprising:

a tibial insert, the tibial insert including an articular surface, and

a femoral component comprising a condyle configured to articulate on the articular surface of the tibial insert, the condyle comprising a femoral articular surface having a first radius of curvature extending posteriorly to a first degree of flexion of 70 degrees or less and a plurality of decreasing radii of curvature extending posteriorly from the first degree of flexion to a second degree of flexion greater than the first degree of flexion,

wherein the articular surface of the tibial insert includes a dwell point having an arcuate or elliptical shape when viewed in a transverse plane and an anterior lip having a height relative to the dwell point of at least nine millimeters.

29. The orthopaedic system of claim 29, wherein the femoral articular surface of the femoral component has a second radius of curvature at the second degree of flexion, wherein the second radius of curvature is greater than a last radius of the plurality of reduced radii of curvature.

30. The orthopedic system according to claim 30, wherein the second radius of curvature is posterior to the reduced radius of curvature.

31. The orthopedic system according to claim 30, wherein the articular surface of the tibial insert and the femoral articular surface of the condyle have a medial-lateral conformity of at least 93%.

Technical Field

The present invention relates to orthopaedic systems, and more particularly, to orthopaedic systems for performing knee replacement surgery.

Background

Arthroplasty is a well-known surgical procedure by which a diseased and/or damaged natural joint may be replaced with a prosthetic joint. A typical knee prosthesis includes a tibial tray, a femoral component, and a polymeric insert or bearing positioned between the tibial tray and the femoral component. Depending on the severity of the patient's joint damage, orthopaedic prostheses of different mobility may be used. For example, in situations where it is desirable to limit the motion of a knee prosthesis, such as when there is significant soft tissue damage or loss, the knee prosthesis may include a "fixed" tibial insert. Alternatively, in cases where greater freedom of motion is desired, the knee prosthesis may include a "living" tibial insert. Additionally, the knee prosthesis may be a total knee prosthesis designed to replace the femoral-tibial interface of both condyles of a patient's femur or a unicompartmental (or unicondylar) knee prosthesis designed to replace the femoral-tibial interface of a single condyle of a patient's femur.

The type of orthopaedic knee prosthesis used to replace a patient's natural knee may also depend on whether the patient's posterior cruciate ligament is retained or sacrificial (i.e., removed) during surgery. For example, if the patient's posterior cruciate ligament is damaged, diseased, and/or otherwise removed during surgery, a posterior stabilized knee prosthesis may be used to provide additional support and/or control at later degrees of flexion. Alternatively, if the posterior cruciate ligament is intact, a knee prosthesis retaining the cruciate ligament may be used.

Typical orthopaedic knee prostheses are generally designed to replicate the natural motion of the patient's joint. As the knee joint flexes and extends, the femoral and tibial components articulate and undergo a combination of relative anterior-posterior motion and relative medial-lateral rotation. However, the surrounding soft tissue of the patient also affects the kinematics and stability of the orthopaedic knee prosthesis throughout the range of motion of the joint. That is, forces exerted by the patient's soft tissue on the orthopaedic components may result in undesirable or undesirable motion of the orthopaedic knee prosthesis. For example, orthopaedic knee prostheses may exhibit unnatural (paradoxical) amounts of anterior translation as the femoral component moves through the range of flexion.

Disclosure of Invention

The present disclosure provides an orthopaedic system having a tibial insert configured to allow asymmetric pivoting of a femoral component supported on the tibial insert; a convex anterior-medial surface conforming to the femoral component; and a geometry that provides stability.

According to one aspect of the present disclosure, an orthopaedic system may include a tibial insert and a femoral component. The tibial insert may include a medial articular surface and a lateral articular surface. The medial and lateral articular surfaces may be asymmetrically shaped relative to one another. The femoral component may include a medial condyle configured to articulate on the medial articular surface of the tibial insert and a lateral condyle configured to articulate on the lateral articular surface of the tibial insert. The medial condyle of the femoral component includes a femoral articular surface having a first radius of curvature extending posteriorly to a first degree of flexion of 70 degrees or less and a plurality of decreasing radii of curvature extending posteriorly from the first degree of flexion to a second degree of flexion greater than the first degree of flexion.

In some embodiments, the femoral articular surface of the femoral component has a second radius of curvature at the second degree of flexion. In such embodiments, the second radius of curvature may be greater than the last radius of the plurality of reduced radii of curvature. Additionally or alternatively, the femoral articular surface of the femoral component can have a second radius of curvature posterior to the reduced radius of curvature that is greater than a last radius of the plurality of reduced radii of curvature.

Additionally, in some embodiments, the medial articular surface of the tibial insert and the femoral articular surface of the medial condyle of the femoral component are more conformal than the lateral articular surface of the tibial insert and the femoral articular surface of the lateral condyle of the femoral component. For example, the medial articular surface and the femoral articular surface of the medial condyle may have an anterior-posterior conformity of at least 96% at zero degrees of flexion. Additionally or alternatively, the medial articular surface of the tibial insert and the femoral articular surface of the medial condyle may have at least 93% internal and external conformity. Additionally or alternatively, the lateral articular surface of the tibial insert and the femoral articular surface of the lateral condyle may have at least 93% internal and external conformity.

In some embodiments, the tibial insert includes an antero-medial lip having a first height and an antero-lateral lip having a second height. In such embodiments, the first height of the forward inboard lip is greater than the second height of the forward outboard lip. Additionally, the medial articular surface of the tibial insert may include a dwell point, and the first height of the anterior-medial lip relative to the dwell point may be at least 9 millimeters. Additionally or alternatively, the medial articular surface of the tibial insert may include a dwell point having an arcuate or elliptical shape when viewed in the transverse plane.

In some embodiments, the medial articular surface of the tibial insert includes a dwell point and an antero-medial lip. In such embodiments, the anterior medial lip has a height relative to the dwell point of at least 9 millimeters. Additionally, in some embodiments, the medial articular surface of the tibial insert may include a dwell point having an arcuate or elliptical shape when viewed in the transverse plane. Additionally, in some embodiments, the first radius of curvature has a length that is between 41% and 47% of an anterior-posterior length of the tibial insert. In some embodiments, the medial articular surface of the tibial insert includes a dwell point, and the lateral articular surface provides an arcuate path for the femoral component to pivot about the dwell point. Additionally, in some embodiments, the first radius of curvature may extend anteriorly to an excessive degree of flexion of 30 degrees or less.

According to another aspect, a tibial insert for a knee replacement system includes a lateral articular surface and a medial articular surface. The lateral articular surface may be configured to articulate with the lateral condyle of the femoral component. Similarly, the medial articular surface may be configured to articulate with the medial condyle of the femoral component. In addition, the medial articular surface is asymmetrically shaped relative to the lateral articular surface and includes a dwell point and an anterior-medial lip having a height relative to the dwell point of at least nine millimeters.

In some embodiments, the medial articular surface and the medial condyle of the femoral component are more conformal than the lateral articular surface and the lateral condyle of the femoral component. Additionally, in some embodiments, the dwell point has an arcuate or elliptical shape when viewed in the transverse plane. Further, in some embodiments, the lateral articular surface may include an antero-lateral lip having a height that is less than a height of the antero-medial lip.

According to yet another aspect, an orthopaedic system may include a tibial insert and a femoral component. The tibial insert may include a lateral articular surface and a medial articular surface. The femoral component may include a medial condyle configured to articulate on the medial articular surface of the tibial insert and a lateral condyle configured to articulate on the lateral articular surface of the tibial insert. The medial condyle of the femoral component may include a femoral articular surface having a first radius of curvature extending posteriorly to a first degree of flexion of 70 degrees or less and a plurality of decreasing radii of curvature extending posteriorly from the first degree of flexion to a second degree of flexion greater than the first degree of flexion. In addition, the medial articular surface of the tibial insert is asymmetrically shaped relative to the lateral articular surface and includes a dwell point having an arcuate or elliptical shape and an anterior-medial lip having a height relative to the dwell point of at least nine millimeters.

In some embodiments, the tibial insert may include an antero-lateral lip, and in such embodiments, the height of the antero-lateral lip is greater than the height of the antero-lateral lip. Additionally, in some embodiments, the femoral articular surface of the femoral component has a second radius of curvature at the second degree of flexion. The second radius of curvature may be greater than a last radius of the plurality of reduced radii of curvature. In some embodiments, the second radius of curvature may be posterior to the reduced radius of curvature.

Additionally, in some embodiments, the medial articular surface of the tibial insert and the femoral articular surface of the medial condyle of the femoral component may be more conformal than the lateral articular surface of the tibial insert and the femoral articular surface of the lateral condyle of the femoral component. For example, the medial articular surface of the tibial insert and the femoral articular surface of the medial condyle may have at least 93% internal and external conformity. In some embodiments, the lateral articular surface may provide an arcuate path for pivoting the femoral component about the dwell point. Additionally, in some embodiments, the first radius of curvature may extend anteriorly to an excessive degree of flexion of 30 degrees or less.

According to yet another aspect, an orthopaedic system includes a tibial insert and a femoral component. The tibial insert may have an articular surface and the femoral component may have a condyle configured to articulate on the articular surface of the tibial insert. The condyle of the femoral component may include a femoral articular surface having a first radius of curvature extending posteriorly to a first degree of flexion of 70 degrees or less and a plurality of decreasing radii of curvature extending posteriorly from the first degree of flexion to a second degree of flexion greater than the first degree of flexion. The articular surface of the tibial insert may include a dwell point having an arcuate or elliptical shape when viewed in the transverse plane and an anterior lip having a height of at least nine millimeters relative to the dwell point.

In some embodiments, the femoral articular surface of the femoral component has a second radius of curvature at the second degree of flexion. In such embodiments, the second radius of curvature may be greater than the last radius of the plurality of reduced radii of curvature. Additionally, in some embodiments, the second radius of curvature is posterior to the reduced radius of curvature. Further, in some embodiments, the articular surface of the tibial insert and the femoral articular surface of the condyle may have at least 93% internal and external conformity.

Drawings

The detailed description refers specifically to the accompanying drawings in which:

FIG. 1 is an anterior perspective view of a tibial insert having an asymmetrical articular surface;

FIG. 2 is an anterior perspective view of a known tibial insert having a symmetrical articular surface;

fig. 3A is a top view of the known tibial insert of fig. 2;

FIG. 3B is a top view of the orthopedic insert of FIG. 1;

FIG. 4 is a side perspective view of an orthopaedic system including the femoral component and tibial insert of FIGS. 1 and 3B;

fig. 5A is a top view of the tibial insert of fig. 1 and 3B;

fig. 5B is a rear elevation view of the tibial insert of fig. 1 and 3B;

fig. 5C is a medial side view of the tibial insert of fig. 1 and 3B;

FIG. 5D is a side view of the orthopedic insert of FIGS. 1 and 3B; and is

Fig. 5E is an anterior elevation view of the tibial insert of fig. 1 and 3B.

Detailed Description

While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intention to limit the concepts of the disclosure to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Throughout the specification, when referring to orthopaedic implants and orthopaedic surgical instruments described herein and the natural anatomy of a patient, terms denoting anatomical reference, such as anterior, posterior, medial, lateral, superior, inferior, and the like, may be used. These terms have well-known meanings in both the anatomical studies and orthopedic fields. Unless otherwise indicated, these anatomical reference terms used in the written detailed description and claims are intended to be consistent with their well-known meaning.

Referring now to the drawings, and more particularly to fig. 1, there is shown an exemplary embodiment of a tibial insert 100 provided in accordance with the present disclosure. For comparison, a known tibial insert 200 is shown in fig. 2. Each tibial insert 100, 200 defines a respective anterior-posterior centerline CL1, CL2 and a medial articular surface 102, 104 on one half of the centerline CL1, CL2, respectively, and a lateral articular surface 104, 114 on the other half of the centerline CL1, CL2, respectively. Unlike the known tibial inserts 200, the articular surfaces 102, 112 of the tibial insert 100 are asymmetrically shaped to provide asymmetric pivoting of the femoral component that is supported on the tibial insert 100. The medial articular surface 102 of the tibial insert 100 is more conformal to the condylar portion of the femoral component, for example, than the medial articular surface 104 of the tibial insert 200, as will be further described herein. In contrast to the tibial insert 200 (antero-medial lip height 144), the tibial insert 100 also has a relatively convex anterior surface (antero-medial lip height 122) on the medial side of the tibial insert 100.

With continued reference to fig. 1, and now also to fig. 3B, the lateral side 310 of the tibial insert 100 provides an arcuate path 312, represented by a curved arrow, for pivoting the femoral component about a medial pivot point 314 extending through the medial articular surface 102. The arcuate path 312 may be laterally centered on the inboard pivot point 314. This pivoting motion is different from the motion paths 302, 304 of the femoral component supported on the tibial insert 200, which are symmetrical, as shown in fig. 3A. Thus, unlike the tibial insert 200, the tibial insert 100 provides a medial pivot point for a femoral component supported on the tibial insert 100.

Referring now to fig. 4, an orthopaedic system 400 is shown that includes a femoral component 410 supported on the tibial insert 100 shown in fig. 1 and 3B. The femoral component 410 includes a medial femoral condyle 412 configured to articulate on the medial articular surface 102 of the tibial insert 100 and a lateral femoral condyle 414 configured to articulate on the lateral articular surface 112. One or both of the femoral condyles 412, 414 may define a radius of curvature extending anteriorly between 10 degrees and 30 degrees. One or both of the femoral condyles 412, 414 may define a radius of curvature 418 that extends anteriorly by 30 degrees or less. Additionally, as shown in fig. 4, the femoral component 410 may also define a constant radius of curvature 420 that extends semi-radially posteriorly to a degree of flexion 422 that is between 30 and 70 degrees before beginning to taper the radius of curvature defining the remainder of the sagittal shape of the femoral component 410 posterior to the degree of flexion 422. The femoral component 410 can define a constant radius of curvature that can extend posteriorly to a degree of flexion 422 of 70 degrees or less before beginning to taper off the radius of curvature defining the remainder of the sagittal shape of the femoral component.

For medial conformal designs with a range of radii of curvature, the choice of conformality is important to define the ability to resist abnormal translation. Some embodiments of the femoral component 410 may have a constant radius of curvature 420 that extends to degrees of flexion of 30 degrees or less and then has a decreasing radius of curvature over a range of degrees of flexion thereafter. Some embodiments may have a radius of curvature 420 that may extend to 70 degrees or less of flexion and then include some radius of curvature that is much smaller in size to define the posterior condyle sagittal shape in deep flexion. For natural medial pivot motion, some embodiments may have a range of higher conformability on the medial side for stability, plus a range of smaller radii of curvature to restore normal gait at deeper flexion angles. The articular surface of the lateral femoral condyle 414 is generally less contoured sagittal than the articular surface of the medial femoral condyle 412. The lateral tibial surface has an arcuate shape generally centered on the lowest position or dwell point/region of the medial conforming surface. In this manner, the dwell point acts as a medial pivot point for the femoral component supported on the tibial insert 100.

The relationship of the anterior-posterior (AP) length 430 of the tibial insert 100 to the size of the radius of curvature 418 of the femoral component 410 is important. If radius of curvature 418 and/or radius of curvature 420 are too large (depending on the particular degree of flexion), a predetermined or hinge effect may occur at mid-flexion. If the radius of curvature 420 is too small, the series of radii of curvature may need to be increased at some point to achieve the desired anteroposterior dimension of the implant. In some embodiments, the radius of curvature 420 may be between 41% and 47% of the anterior-posterior length of the tibial insert 100. The ratio of coronal curvature to sagittal curvature defining the radius of curvature of the portion of the femoral component 410 may be, for example, between 41% and 100%.

Referring now to fig. 5A-5E, the geometry of the tibial insert 100 is shown. As previously described, the medial articular surface 102 of the tibial insert 100 conforms to the femoral component 410. The anterior-posterior surface conformity of the medial articular surface 102 may be at least 96% of the radius of curvature 420 of the femoral component 410 (e.g., at zero flexion). For example, the anterior-posterior conformity between the medial articular surface 102 and the corresponding femoral articular surface of the femoral component 410 may be 96% or greater (e.g., at zero degrees of flexion). The medial and lateral conformity of the medial and lateral articular surfaces 102, 112 may be at least 93% of the medial-lateral condyle radius of curvature of the femoral component 410. For example, the medial and lateral conformity between the medial and lateral articular surfaces 102 and 112 and the corresponding femoral articular surface of the femoral component 410 may be 93% or greater.

For optimum medial stability, it is necessary to extend the radius of extension forward by 20-30 degrees. Although the natural knee joint does not go beyond these degrees, the matching conformity on the tibial surface results in a higher medial anterior surface than most designs. The minimum height of the anterior medial lip 502 (see fig. 5E) may have a height 504 that is at least 9mm higher than the minimum dwell point 506 on the medial articular surface 102 (see fig. 5A). If the height of the surface is 9mm or greater than the lowest articular surface area or dwell point 506, the higher surface increases the overall conformity of the medial articular surface 102 and may reduce the likelihood of dislocation. The intermediate dwell point 506 may be a curved dwell point having an arcuate shape or may be an ellipse having a flat surface no more than 1mm between two curved surfaces.

Another feature of the tibial insert 100 is the location of the dwell point 506 on the medial articular surface 102. If the medial dwell point 506 is too far anteriorly, the artificial knee joint may not be able to reach deeper flexion angles without removing posterior conformity on the tibial surface. If the dwell point 506 on the medial articular surface 102 is too far posteriorly, the anterior surface of the medial articular surface 102 will have difficulty achieving the necessary extension of the artificial knee joint, and excessive posterior loading through the tibia may cause some loosening of the tibial insert 100 from the cement. The dwell positions on both the medial and lateral articular surfaces 102, 112 can coincide with the corresponding condylar portions of the femoral component 410.

With respect to the ratio of conformity of the medial and lateral condyle surfaces of the femoral component 410, this ratio is important to define the pivoting motion. If the coronal radius is too flat, the ability of the implant or orthopedic system to rotate and maintain anterior stability is compromised.

While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.