Patent Description:
Orthopedic procedures and prostheses are commonly utilized to repair and/or replace damaged bone and tissue in the human body. For example, a knee arthroplasty can be used to restore natural knee function by repairing damaged or diseased articular surfaces of the femur and/or tibia. An incision is made into the knee joint to expose the bones comprising the joint. Cut guides are used to guide the removal of the articular surfaces that are to be replaced. Prostheses are used to replicate the articular surfaces. Knee prostheses can include a femoral prosthesis implanted on the distal end of the femur, which articulates with a tibial bearing component and a tibial component implanted on the proximal end of a tibia to replicate the function of a healthy natural knee. Various types of arthroplasties are known including a total knee arthroplasty, where all of the articulating compartments of the joint are repaired with prosthetic components. <CIT> describes a femoral component for a knee prosthesis.

This disclosure pertains generally to femoral prostheses and systems for a knee arthroplasty including a revision knee arthroplasty. The present inventors have recognized, among other things, that it is desirable to offer versatile sizing options with regards to a combination of femoral posterior condylar offset and femoral medial-lateral condylar extent. More particularly, the present inventors have recognized a femoral prosthesis system that can have a plurality of sizing options using two families of femoral prostheses. The second family of femoral prostheses has a predetermined increase in the femoral posterior condylar offset relative to the first family of femoral prosthesis. In one example, the second family of femoral prostheses can have the predetermined increase in the femoral posterior condylar offset while maintaining substantially the same femoral medial-lateral condylar extent relative to the first family of femoral prostheses. Thus, for example, if sizing criteria dictate, a femoral prosthesis of a first size from the second family can be selected having a relatively larger femoral posterior condylar offset but a same femoral medial-lateral condylar extent to a correspondingly sized femoral prosthesis from the first family. Similarly, the systems allow for downsizing should sizing criteria dictate. For example, a femoral prosthesis of a first size from the first family can be selected having a femoral medial-lateral condylar extent that is larger than desired but having a femoral posterior condylar offset that is sized as desired. In such situation, the disclosed examples allow a correspondingly sized femoral prosthesis from the second family to be selected that has substantially a same femoral posterior condylar offset but a femoral medial-lateral condylar extent that differs from that of the femoral prosthesis of the first size from the first family by a predetermined amount. Such sizing versatility allows a patient appropriate femoral prosthesis from the first family or the second family to be selected more easily (e.g., selection is made using a consistent logical upsizing or downsizing scheme).

Regarding the first family of femoral prostheses, according to one example, the first family of femoral prostheses have a first range of posterior condylar offsets and a corresponding range of femoral medial-lateral condylar extents. The range for the femoral medial-lateral condylar extent of the first family can be between about <NUM> (for a size <NUM> femoral prosthesis) and about <NUM> (for a size <NUM> femoral prosthesis), for example. Similarly, the range of the posterior condylar offset can be between about <NUM> (for the size <NUM> femoral prosthesis) to about <NUM> (for the size <NUM> femoral prosthesis), for example. According to some examples, the femoral medial-lateral condylar extent can be substantially linearly incremented in a size increase from the size <NUM> to the size <NUM> femoral prosthesis such that for each increase in femoral size (e.g., going from a size <NUM> to size <NUM> or from a size <NUM> to a size <NUM>) there is a corresponding known increase in the femoral medial-lateral condylar extent. The posterior condylar offset can be similarly substantially linearly incremented such that there is a known increase when moving up or down in prostheses size.

The present inventors have additionally recognized the prosthesis system can have the second family of femoral prostheses be compatible with the same tibial bearing component as a correspondingly sized femoral prosthesis from the first family of femoral prostheses. According to some examples, the second family of femoral prostheses can have a second range of posterior condylar offsets and corresponding femoral medial-lateral condylar extents. The range for the femoral medial-lateral condylar extent of the first family can be between about <NUM> (for a size <NUM>+ femoral prosthesis) and about <NUM> (for a size <NUM>+ femoral prosthesis), for example. Similarly, the range of the posterior condylar offset can be between about <NUM> (for the size <NUM>+ femoral prosthesis) to about <NUM> (for the size <NUM>+ femoral prosthesis), for example. According to some examples, the femoral medial-lateral condylar extent can be substantially linearly incremented in a size increase from the size <NUM>+ to the size <NUM>+ femoral prosthesis such that for each increase in femoral size there is a corresponding increase in the femoral medial-lateral condylar extent. The posterior condylar offset can be similarly substantially linearly incremented such that there is a known increase when moving up or down in prostheses size.

As discussed above, the size increase for the first family of femoral prostheses and the size increase for the second family of femoral prostheses can be related so as to be substantially the same (See FIGS. 4A-4C) according to some examples. However, the posterior condylar offset between the first family and the second family can be offset in that the femoral prostheses from the second family are always larger by a known amount (e.g., <NUM>) in the posterior condylar offset.

The invention provides a system for knee arthroplasty as defined in claim <NUM>.

The system optionally can include the at least one of the first plurality of femoral prostheses and the at least one of the second plurality of femoral prostheses are configured to articulate with a same tibial bearing component.

The system optionally can include the first posterior condylar offset of the at least one of the first plurality of femoral prostheses and the second posterior condylar offset of the at least one of the second plurality of femoral prostheses differ by a predetermined amount.

The system optionally can include the predetermined amount comprises substantially <NUM>, and wherein the second medial condyle and a second lateral condyle are thickened along a posterior portion comprising at least a region between a posterior bone-contacting surface and a posterior portion of the J-curve when viewed in a sagittal plane relative to a corresponding thickness of the first medial condyle and the first lateral condyle.

The system optionally can include the first posterior condylar offset of at least four of the first plurality of the femoral prostheses is substantially the same as the second posterior condylar offset of at least four of the second plurality of femoral prostheses.

The system optionally can include the first posterior condylar offset of at least six of the first plurality of the femoral prostheses is substantially the same as the second posterior condylar offset of at least six of the second plurality of femoral prostheses.

The system optionally can include the first femoral medial-lateral condylar extent of at least four of the first plurality of the femoral prostheses is substantially the same as the second femoral medial-lateral condylar extent of at least four of the second plurality of femoral prostheses.

The system optionally can include the first femoral medial-lateral condylar extent of at least six of the first plurality of the femoral prostheses is substantially the same as the second femoral medial-lateral condylar extent of at least six of the second plurality of femoral prostheses.

The system optionally can include each of the different stock sizes of the first plurality of femoral prostheses differ with respect to the first femoral medial-lateral condylar extent by a first amount between a smaller size and a next larger size and each of the different stock sizes of the second plurality of femoral prostheses differ with respect to the second femoral medial-lateral condylar extent by a second amount between a corresponding smaller size and a corresponding next larger size, and wherein the first amount is substantially the same as the second amount.

The system optionally can include each of the different stock sizes of the first plurality of femoral prostheses differ with respect to the first posterior condylar offset by a third amount between a smaller size and a next larger size and each of the different stock sizes of the second plurality of femoral prostheses differ with respect to the second posterior condylar offset by a fourth amount between a corresponding smaller size and a corresponding next larger size, and wherein the third amount is substantially the same as the fourth amount.

These and other examples and features of the present devices and systems will be set forth in part in the following Detailed Description. This overview is intended to provide a summary of subject matter of the present patent application. It is not intended to provide an exclusive or exhaustive removal of the invention.

In the drawings, which are not necessarily drawn to scale, like numerals can describe similar components in different views. Like numerals having different letter suffixes can represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various examples discussed in the present document.

The present disclosure relates to a system for knee arthroplasty as defined in claim <NUM>.

The present application relates to prostheses and systems that can be used in a knee arthroplasty and/or as part of a later knee revision surgery. As described herein, the term system or assembly can include both tibial prosthesis and a femoral prosthesis. This application focuses on aspects of the femoral prosthesis, which can include the stem housing, the medial condyle and the lateral condyle. As discussed previously, the femoral prostheses can be part of the system used to simplify sizing and offer various femoral options that can be compatible with the same tibial bearing component. Additional features and benefits of the various examples provided herein will be discussed and/or will be apparent to one of ordinary skill in the art.

As used herein, the terms "proximal" and "distal" should be given their generally understood anatomical interpretation. The term "proximal" refers to a direction generally toward the torso of a patient, and "distal" refers to the opposite direction of proximal, i.e., away from the torso of a patient. It should be understood that the use of the terms "proximal" and "distal" should be interpreted as though the patient were standing with the knee joint in extension despite the apparatuses described herein generally being used with the knee joint in flexion. The intent is to differentiate the terms "proximal" and "distal" from the terms "anterior" and "posterior". As used herein, the terms "anterior" and "posterior" should be given their generally understood anatomical interpretation. Thus, "posterior" refers to a rear of the patient, e.g., a back of the knee. Similarly, "anterior" refers to a front of the patient, e.g., a front of the knee. Thus, "posterior" refers to the opposite direction of "anterior". Similarly, the term "lateral" refers to the opposite direction of "medial".

<FIG> illustrates a prosthesis assembly <NUM> that can be used as part of a system <NUM> described herein. The assembly <NUM> and system <NUM> can include a femoral prosthesis <NUM> and a tibial prosthesis <NUM>. In the example of <FIG>, the prosthesis assembly <NUM> is shown in a perspective view with the femoral prosthesis <NUM> articulated relative to the tibial prosthesis <NUM> to <NUM>° of flexion. <FIG>, <FIG> show various examples of the femoral prosthesis <NUM> (sometimes indicated with other reference numbers) in a cross-sectional view along a sagittal plane. The sagittal plane extends along the anterior-posterior direction and the proximal-distal direction of the femoral prosthesis illustrated.

According to the examples provided herein, the prosthesis assembly <NUM> and system <NUM> can utilize posterior stabilized (PS) prostheses. Thus, the tibial prosthesis <NUM> can include a spine <NUM> and the femoral prosthesis <NUM> can include a cam <NUM> (<FIG>). The spine <NUM> and the cam <NUM> can designed to cooperate with one another to stabilize the femoral prosthesis <NUM> with respect to tibial prosthesis <NUM> in lieu of a posterior cruciate ligament (PCL). However, other prosthesis designs are contemplated including a mid-level constraint (MLC) design, a cruciate retaining (CR) design, a constrained condylar (CC), an ultra-congruent (UC) design, for example. CR tibial prostheses are generally used in surgical procedures which retain the PCL. The CR and UC designs omit the spine <NUM> and cam <NUM>. In any case, the femoral prosthesis <NUM> defines an intercondylar space <NUM> between medial and lateral condyles <NUM> and <NUM> (shown in <FIG> and <FIG>). In the case of a CR or UC, this intercondylar space can entirely open and uninterrupted by the cam <NUM> as it is in <FIG>, <FIG>.

Turning to the components illustrated in <FIG>, the tibial prosthesis <NUM> can include a tibial bearing component <NUM> and a tibial baseplate <NUM>. The tibial bearing component <NUM> can include the spine <NUM> (<FIG>), a proximal medial articular surface <NUM> and a proximal lateral articular surface <NUM>. The tibial baseplate <NUM> can include a keel <NUM>. Additional components such as a stem <NUM> can be used with the prosthesis assembly <NUM> in some examples.

As shown in <FIG>, the femoral prosthesis <NUM> can be disposed atop and can articulate relative to the tibial prosthesis <NUM>. Such articulation can be between the medial and lateral femoral condyles <NUM> and <NUM> and the proximal medial articular surface <NUM> and the proximal lateral articular surface <NUM>, respectively. The proximal medial articular surface <NUM> and the proximal lateral articular surface <NUM> can be shaped (e.g., curved) to facilitate such articulation during knee joint flexion. The spine <NUM> (<FIG>) of the tibial bearing component <NUM> can be centrally located between the proximal medial articular surface <NUM> and the proximal lateral articular surface <NUM>. The spine <NUM> can be configured to engage with the cam <NUM> during flexion. Such engagement provides additional stability that would otherwise be offered by ligaments such as the PCL.

The tibial bearing component <NUM> can be secured to the tibial baseplate <NUM> as shown in <FIG>. Such securement can be facilitated by the use of rails, notches, bosses, an insert, and/or fastener according to various examples.

<FIG> show the femoral prosthesis <NUM>. <FIG> shows the femoral prosthesis <NUM> from a posterior-medial position. <FIG> shows the femoral prosthesis <NUM> in a cross-section along the sagittal plane, the cross-section extending along the intercondylar space <NUM> and bisecting the cam <NUM>.

<FIG> show the cam <NUM>, which can have multiple radii according to the illustrated example. In addition to the medial and lateral condyles <NUM> and <NUM> (only the medial condyle <NUM> is shown in <FIG>), the femoral prosthesis <NUM> can include a posterior bone-interfacing surface <NUM> (shown partially dashed in <FIG>), a posterior bone-interfacing chamfer surface <NUM> (shown dashed in <FIG>), a distal bone-interfacing surface <NUM> (shown dashed in <FIG>), an anterior bone-interfacing chamfer surface <NUM> (not shown in <FIG>), an anterior bone-interfacing surface <NUM> (not shown in <FIG>) and a stem housing <NUM>. The medial and lateral condyles <NUM> and <NUM> can include medial and lateral articular surfaces 52A and 52B, respectively. When viewed in the sagittal plane, (as in <FIG>) the articular surfaces 52A and 52B can form J-curves (only one is shown in <FIG>).

The cam <NUM> can be positioned at a posterior end of the intercondylar space <NUM> and can extend between the medial and lateral condyles <NUM> and <NUM>. As shown in <FIG>, portions of the posterior bone-interfacing surface <NUM>, the posterior bone-interfacing chamfer surface <NUM>, the distal bone-interfacing surface <NUM>, the anterior bone-interfacing chamfer surface <NUM> and the anterior bone-interfacing surface <NUM> can be formed by the medial and lateral condyles <NUM> and <NUM>. The medial and lateral articular surfaces 52A and 52B can be disposed opposite (spaced by a thickness of the medial and lateral condyles <NUM> and <NUM>) from the posterior bone-interfacing surface <NUM>, the posterior bone-interfacing chamfer surface <NUM>, the distal bone-interfacing surface <NUM>, the anterior bone-interfacing chamfer surface <NUM> and the anterior bone-interfacing surface <NUM>. The medial and lateral condyles <NUM> and <NUM> can have varying thicknesses both medial-lateral and anterior-posterior.

The posterior bone-interfacing surface <NUM>, the posterior bone-interfacing chamfer surface <NUM>, the distal bone-interfacing surface <NUM>, the anterior bone-interfacing chamfer surface <NUM> and the anterior bone-interfacing surface <NUM> are configured to abut resected portions of the femur (not shown) upon implantation of the femoral prosthesis <NUM>. The stem housing <NUM> can be positioned generally between the medial and lateral condyles <NUM> and <NUM> and can be coupled thereto. The stem housing <NUM> can be positioned anterior of the intercondylar space <NUM>. The stem housing <NUM> can extend generally proximally and can be symmetrical about a first axis A as shown in <FIG>. In some examples, the stem housing <NUM> can be canted medial-lateral so as to be both extend medial-lateral and proximal in extent from interconnection between the medial and lateral condyles <NUM> and <NUM>.

<FIG> shows examples of femoral prostheses <NUM>, <NUM> that can be used according to a system <NUM>. The femoral prostheses <NUM>, <NUM> can be configured in a manner similar to that of the example femoral prosthesis <NUM> previously described. The femoral prosthesis <NUM> can be from a first family <NUM> of femoral prostheses of which the femoral prosthesis <NUM> is exemplary of one distinct predetermined size. Similarly, the femoral prosthesis <NUM> can be from a second family <NUM> of femoral prostheses of which the femoral prosthesis <NUM> is exemplary of one distinct predetermined size. The femoral prosthesis <NUM> can be similar in size with respect to the femoral prosthesis <NUM> according to some examples. Such similarity can be that a medial-lateral condylar extent (shown subsequently) of the femoral prosthesis <NUM> can be substantially the same as the medial-lateral condylar extent of the femoral prosthesis <NUM>. Thus, according to some examples, the femoral prostheses <NUM>, <NUM> can be compatible to articulate with the same tibial prosthesis (i.e. the same bearing component) as is discussed further subsequently. The medial-lateral condylar extent is illustrated in reference to <FIG> and can comprise a distance from a medial most edge of the medial condyle to a lateral most edge of the lateral condyle.

However, as shown in <FIG>, the femoral prosthesis <NUM> can differ in size from the femoral prosthesis <NUM> in that the femoral prosthesis <NUM> has a different thickness <NUM> between at least the posterior bone-interfacing surface <NUM> and the articular surface <NUM> than the femoral prosthesis <NUM>. Thus, a thickness <NUM> between the posterior bone-interfacing surface <NUM> and the articular surface <NUM> differs from the thickness <NUM> as shown in the example of <FIG>. Thus, for the femoral prosthesis <NUM>, the second medial condyle <NUM> and the second lateral condyle (only the medial condyle <NUM> is shown in <FIG>) are thickened along a posterior portion <NUM> comprising at least a region between the posterior bone-contacting surface <NUM> and a posterior portion of the J-curve <NUM> when viewed in a sagittal plane relative to a corresponding thickness of the first medial condyle and the first lateral condyle of the femoral prosthesis <NUM>.

Due to the difference between the thickness <NUM> and the thickness <NUM>, the femoral prosthesis <NUM> can have a posterior condylar offset <NUM> that differs from a posterior condylar offset <NUM> of the femoral prosthesis <NUM>. According to some examples, the posterior condylar offset <NUM> can differ from the posterior condylar offset <NUM> by a predetermined amount (e.g., <NUM>, <NUM>, <NUM>, <NUM> or <NUM>). Indeed, in the illustrated embodiment of <FIG>, the predetermined amount can comprise substantially <NUM> difference between the posterior condylar offset <NUM> and the posterior condylar offset <NUM>.

<FIG> shows a femoral prosthesis <NUM> that can comprise one of either the first family of femoral prostheses <NUM> or the second family of femoral prostheses <NUM> discussed subsequently in regards to <FIG>. As shown in <FIG>, the femoral prosthesis <NUM> can include a medial-lateral condylar extent <NUM> and a posterior condylar offset <NUM>.

The medial-lateral condylar extent <NUM> can be from a medial most edge <NUM> of a medial condyle <NUM> to a lateral most edge <NUM> of a lateral condyle <NUM>. The posterior condylar offset <NUM> can extend from an axis A of a stem housing <NUM> to a posterior-most point P of at least one of the medial condyle <NUM> and the lateral condyle <NUM>.

<FIG> provide a system <NUM> comprised of the first family of femoral prostheses <NUM> and the second family of femoral prostheses <NUM>. Each of the first family of femoral prostheses <NUM> and the second family of femoral prostheses <NUM> include a plurality of distinct sizes as shown in the plot of <FIG>. In the example of <FIG>, the first family of femoral prostheses <NUM> can have seven distinct sizes indicated as sizes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. The second family of femoral prostheses <NUM> can have six distinct sizes indicated as sizes <NUM>+, <NUM>+, <NUM>+, <NUM>+, <NUM>+ and <NUM>+.

According to the example of <FIG>, the posterior condylar offset of at least four of the first family of femoral prostheses <NUM> (the first family of femoral prostheses <NUM> being of different distinct sizes from one another) can be substantially the same as the posterior condylar offset of at least four of the second family of femoral prostheses <NUM> (the second family of femoral prosthesis <NUM> being of different distinct sizes from one another). According to some examples, the posterior condylar offset of at least six of the first family of femoral prostheses <NUM> can be substantially the same as the posterior condylar offset of at least six of the second family of femoral prostheses <NUM> (e.g., sizes <NUM> and <NUM>+ can have substantially the same posterior condylar offset, sizes <NUM> and <NUM>+ can have substantially the same posterior condylar offset, sizes <NUM> and <NUM>+ can have substantially the same posterior condylar offset, sizes <NUM> and <NUM>+ can have substantially the same posterior condylar offset, sizes <NUM> and <NUM>+ can have substantially the same posterior condylar offset and sizes <NUM> and <NUM>+ can share substantially the same posterior condylar offset).

Similarly, the femoral medial-lateral condylar extent of at least four of the first family of femoral prostheses <NUM> (the first family of femoral prostheses <NUM> being of different distinct sizes from one another) can substantially the same as the femoral medial-lateral condylar extent of at least four of the second family of femoral prostheses <NUM> (the second family of femoral prosthesis <NUM> being of different distinct sizes from one another). According to some examples, the femoral medial-lateral condylar extent of at least six of the first family of femoral prostheses <NUM> can be substantially the same as the femoral medial-lateral condylar extent of at least six of the second family of femoral prostheses <NUM> (e.g., sizes <NUM> and <NUM>+ can have substantially the same femoral medial-lateral condylar extent, sizes <NUM> and <NUM>+ can have substantially femoral medial-lateral condylar extent, sizes <NUM> and <NUM>+ can have substantially the same femoral medial-lateral condylar extent, sizes <NUM> and <NUM>+ can have substantially the same femoral medial-lateral condylar extent, sizes <NUM> and <NUM>+ can have substantially the same femoral medial-lateral condylar extent and sizes <NUM> and <NUM>+ can share substantially the same femoral medial-lateral condylar extent).

As shown in <FIG>, each of the different stock sizes of the first family of plurality of femoral prostheses <NUM> can differ with respect to the femoral medial-lateral condylar extent by a first amount (e.g., a few mm such as <NUM>) between a smaller size and a next larger size and each of the different stock sizes. Similarly, the second family of femoral prostheses <NUM> can differ with respect to the femoral medial-lateral condylar extent by a second amount (e.g., a few mm such as <NUM>) between a corresponding smaller size and a corresponding next larger size. In some cases, the first amount can be substantially the same as the second amount.

<FIG> shows that the system <NUM> can have the first family of femoral prostheses <NUM> be compatible with the second family of femoral prostheses <NUM> for a flexion fill. In particular, up to six of the first family of femoral prostheses <NUM> can be compatible with corresponding sizes of the second family of femoral prostheses <NUM> such that the posterior condylar offset can be changed by swapping a particular size of prosthesis from the first family of femoral prostheses <NUM> for a corresponding size of the second family of femoral prostheses <NUM> (e.g., a size <NUM> can be swapped for a size <NUM>+, etc.). According to the example of <FIG>, the posterior condylar offset can be changed by a predetermined amount (e.g., <NUM>) when swapping a particular size of prosthesis from the first family of femoral prostheses <NUM> for a corresponding size of the second family of femoral prostheses <NUM>. Furthermore, according to the example of <FIG>, while the posterior condylar offset can be changed, the femoral medial-lateral condylar extent between the first size of the first family of femoral prostheses <NUM> and the correspondingly size of the second family of femoral prostheses <NUM> can remain substantially the same.

<FIG> shows the system <NUM> can be used for a downsizing in the femoral medial-lateral condylar extent while the flexion fill can be maintained. In particular, up to six of the first family of femoral prostheses <NUM> can be compatible with other sizes of the second family of femoral prostheses <NUM> such that the femoral medial-lateral condylar extent can be changed by swapping a particular size of prosthesis from the first family of femoral prostheses <NUM> for a second size of the second family of femoral prostheses <NUM> (e.g., a size <NUM> can be swapped for a size <NUM>+, etc.). According to the example of <FIG>, while the femoral medial-lateral condylar extent can be changed, the posterior condylar offset between the first size of the first family of femoral prostheses <NUM> and the second size of the second family of femoral prostheses <NUM> can remain substantially the same.

<FIG> shows a sizing chart for the family of tibial baseplates <NUM> relative to the first and second families of femoral prostheses <NUM>, <NUM>. As shown in <FIG> the least one of the first family of femoral prostheses <NUM> and the least one of the second family of femoral prostheses <NUM> can be configured to articulate with a same tibial bearing component. More particularly, the sizing chart shows the first and second families of femoral prostheses <NUM>, <NUM> can have at least thirteen different stock sizes <NUM> to <NUM> (including + sizes). As previously discussed and illustrated, each femoral prosthesis of the first and second families can be of a same design class but can include distinct sizes having different femoral medial-lateral condylar extent and/or posterior condylar offset.

The family of tibial baseplates <NUM> can have at least nine different stock sizes A to J. As shown in <FIG>, a family of tibial bearing components <NUM> can be configured such that eleven stock sizes exist and that combinations of the at least nine different stock sizes of the family of tibial baseplates are compatible for operable use (e.g. to facilitate a desired articulation similar to that of a natural knee) with the at least thirteen different stock sizes of the first and second families of femoral prostheses <NUM>, <NUM>.

<FIG> also illustrates that at least six of the different stock sizes of tibial bearing components <NUM> are configured to be are compatible with at least four of the thirteen stock sizes of femoral prostheses while also being compatible with at least two of the tibial components <NUM>.

According to further examples, eleven of the at least thirteen different stock sizes of the first and second families of femoral prostheses <NUM>, <NUM> can be compatible for operable use with nine of the at least eleven different stock sizes of the family of tibial bearing components <NUM>. According to further examples, twelve of the at least thirteen different stock sizes of the first and second families of femoral prostheses <NUM>, <NUM> can be compatible for operable use with at least two of the at least eleven different stock sizes of the tibial bearing baseplates <NUM>.

This overlapping sizing and the provision of many different compatible sizes can have benefits including providing for increased stability of the medial condyle of the femoral prosthesis. Additionally, the overlapping sizing allows for the flexion fill and downsizing in the femoral medial-lateral condylar extent as discussed previously with respect to <FIG>.

<FIG> provides a specific example of the downsizing in the femoral medial-lateral condylar extent while the flexion fill (substantially the same posterior condylar offset) can be maintained as previously discussed in reference to <FIG>. <FIG> shows a geometry of a first prosthesis <NUM> of a first size (e.g., size <NUM>) of the first family of femoral prostheses <NUM> in a sagittal plane superimposed on the geometry of a second prosthesis <NUM> of a second size (e.g., size <NUM>+) of the second family of femoral prostheses <NUM> in a sagittal plane.

<FIG> shows the first prosthesis <NUM> can include one of a first medial condyle or first lateral condyle (collectively <NUM>). Similarly, the second prosthesis <NUM> can include one of a second medial condyle or second lateral condyle (collectively <NUM>).

As shown in <FIG>, at least one of the first medial condyle and the first lateral condyle <NUM> can have a first thickness T1 at a posterior portion <NUM> between a first posterior bone-contacting surface <NUM> and the first posterior-most point P1. Similarly, at least one of the second medial condyle and the second lateral condyle <NUM> can have a second thickness T2 at a corresponding posterior portion <NUM> between a second posterior bone-contacting surface <NUM> and the second posterior-most point P2 (points P1 and P2 can be disposed at a same posterior location). As shown in <FIG>, according to some examples the first thickness T1 can differ from the second thickness T2 by a predetermined amount (e.g., X as shown in <FIG>).

According to the example of <FIG>, a third thickness of at least one of the first medial condyle and the first lateral condyle <NUM> as measured between a first posterior chamfer <NUM> and an articular surface <NUM> of the first prosthesis <NUM> differs by a predetermined amount Y from a fourth thickness of at least one of the second medial condyle and the second lateral condyle <NUM> as measured between a corresponding second posterior chamfer <NUM> and a corresponding articular surface <NUM> of the second prosthesis <NUM>.

In some examples, an anterior bone-contacting surface <NUM> of the second prosthesis <NUM> (one of the second plurality of femoral prostheses <NUM> previously discussed) can be disposed relatively nearer to a stem housing axis A by another predetermined amount Z than a corresponding anterior bone-contacting surface <NUM> of the first prosthesis <NUM> (one of the first plurality of femoral prostheses <NUM>).

As previously discussed, the downsizing in the femoral medial-lateral condylar extent can be by a predetermined amount (e.g., a few mm). Similarly, the predetermined amount X can be substantially <NUM> (or another desired amount), the predetermined amount Y can comprise substantially <NUM> (or another desired amount) and the predetermined amount Z comprises substantially <NUM> (or another desired amount).

At least one of the first medial condyle and the first lateral condyle <NUM> and at least one of the second medial condyle and the second lateral condyle <NUM> can have a similar sagittal J-curve <NUM> along a posterior and distal portion thereof <NUM> from the first and second posterior-most points P1 and P2, respectively, to a point distal of the stem housing <NUM>, respectively.

Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one
or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) can be used in combination with each other. Other examples can be used, such as by one of ordinary skill in the art upon reviewing the above description.

Claim 1:
A system (<NUM>, <NUM>, <NUM>) for knee arthroplasty comprising:
a first family having a first plurality of femoral prostheses (<NUM>, <NUM>) with different stock sizes from one another, each of the first plurality of femoral prostheses having:
a first medial condyle (<NUM>, <NUM>) and a first lateral condyle (<NUM>, <NUM>);
wherein the first medial condyle and the first lateral condyle have a first femoral medial-lateral condylar extent (<NUM>) from a medial most edge of the first medial condyle to a lateral most edge of the first lateral condyle;
a second family having a second plurality of femoral prostheses (<NUM>, <NUM>) with different stock sizes from one another, each of the second plurality of femoral prostheses having:
a second medial condyle (<NUM>, <NUM>) and a second lateral condyle (<NUM>, <NUM>);
wherein the second medial condyle and the second lateral condyle have a second femoral medial-lateral condylar extent (<NUM>) from a medial most edge of the second medial condyle to a lateral most edge of the second lateral condyle;
characterized in that:
each of the first plurality of femoral prostheses also has a first stem housing (<NUM>, <NUM>, <NUM>) extending along a first axis (A), the first medial condyle (<NUM>, <NUM>) and the first lateral condyle (<NUM>, <NUM>) coupled to the first stem housing;
wherein the first medial condyle and the first lateral condyle have a first posterior condylar offset (<NUM>) as measured from the first axis to a first posterior-most point of the first medial condyle and the first lateral condyle; and
each of the second plurality of femoral prostheses also has a second stem housing (<NUM>, <NUM>, <NUM>) extending along a second axis, the second medial condyle (<NUM>, <NUM>) and the second lateral condyle (<NUM>, <NUM>) coupled to the second stem housing,
wherein the second medial condyle and the second lateral condyle have a second posterior condylar offset (<NUM>) from the second axis to a second posterior-most point of the second medial condyle and the second lateral condyle, and
wherein the first femoral medial-lateral condylar extent of at least one of the first plurality of femoral prostheses and the second femoral medial-lateral condylar extent of at least one of the second plurality of femoral prostheses are substantially the same.