POSTERIOR-STABILIZED KNEE IMPLANTS, DESIGNS AND RELATED METHODS AND TOOLS

Abstract

Patient-adapted articular repair systems, including implants, instruments, and surgical plans, and methods of making and using such systems, are disclosed herein. In particular, various embodiments include knee joint articular repair systems designed for posterior stabilization, including patient-adapted posterior-stabilizing features.

Description

TECHNICAL FIELD

The present application relates to articular repair systems (e.g., resection cut strategy, guide tools, and implant components) as described in, for example, U.S. patent application Ser. No. 13/397,457, entitled “Patient-Adapted and Improved Orthopedic Implants, Designs And Related Tools,” filed Feb. 15, 2012, and published as U.S. Patent Publication No. 2012-0209394, which is incorporated herein by reference in its entirety. In particular, various embodiments disclosed herein provide improved features for knee joint articular repair systems designed for posterior stabilization, including patient-adapted (e.g., patient-specific and/or patient-engineered) features.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, unless otherwise denoted herein, “M” and “L” in certain figures indicate medial and lateral sides of the view, respectively; “A” and “P” in certain figures indicate anterior and posterior sides of the view, respectively; and “S” and “I” in certain figures indicate superior and inferior sides of the view, respectively.

FIGS. 1A and B are perspective views of an exemplary posterior-stabilized femoral implant component;

FIGS. 2A and 2B are side views of exemplary posterior-stabilized implant systems;

FIGS. 3A through 3K depict various patient-adapted femoral intercondylar box embodiments;

FIGS. 3L through 3P depict various cross-sections of the internal surfaces of various intercondylar box embodiments;

FIGS. 4A-4R illustrate sagittal cross-sections of femoral components with exemplary cams features;

FIGS. 5A and 5B depict coronal cross-sections of exemplary post embodiments;

FIGS. 6A and 6B depict perspective views of exemplary posterior-stabilized tibial components;

FIG. 7A is a perspective view of a posterior-stabilized femoral implant component with a cam tongue;

FIGS. 7B through 7F are sagittal cross-section views of exemplary posterior-stabilized implant components with a cam tongue;

FIG. 8 is a perspective view of a patient-adapted femoral jig;

FIG. 9 is a perspective view of a patient-adapted femoral jig for a posterior-stabilized implant;

FIG. 10 is a top view of a posterior-stabilized tibial implant component;

FIG. 11 is a sagittal cross-section of posterior-stabilized femoral and tibial implant components;

FIG. 12A is a perspective view of an exemplary tibial post embodiment;

FIG. 12B depicts transverse cross-sections of the tibial post of FIG. 12A;

FIGS. 13A and 13B are sagittal cross-sections of exemplary posterior-stabilized tibial implant post embodiments;

FIG. 14 is a top view of a two-piece posterior-stabilized tibial implant component embodiment;

FIG. 15 is a top view of a two-piece tibial implant component embodiment;

FIGS. 16 through 27B depict various sagittal cross-sectional views of modeled relationships of femoral and tibial implant components for designing a femoral cam;

FIG. 28 is a superior view of exemplary femoral and tibial posterior-stabilized implant component embodiments;

FIG. 29 is a posterior view of an exemplary femoral posterior-stabilized implant component embodiment;

FIG. 30 is a perspective view of exemplary femoral and tibial posterior-stabilized implant component embodiments;

FIG. 31 is a perspective view of an exemplary tibial implant component embodiment;

FIG. 32 is a superior view of a model of a patient's tibia; and

FIG. 33 depicts a sagittal cross-sectional view of modeled femoral and tibial implant components positioned relative to each other in hyper-extension.

DETAILED DESCRIPTION OF THE INVENTION

In this application, the use of the singular includes the plural unless specifically stated otherwise. Furthermore, the use of the term “including,” as well as other forms, such as “includes” and “included,” is not limiting. Also, terms such as “element” or “component” encompass both elements and components comprising one unit and elements and components that comprise more than one subunit, unless specifically stated otherwise. Also, the use of the term “portion” may include part of a moiety or the entire moiety.

The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described or the combination of features and/or embodiments described under one heading with features and/or embodiments described under another heading.

Selecting and/or Designing a Patient-Adapted Implant Component

As described herein, an implant (also referred to as an “implant system”) can include one or more implant components, which, can each include one or more patient-specific features, one or more patient-engineered features, and one or more standard (e.g., off-the-shelf, non-patient-specific) features. Moreover, an implant system can include one or more patient-adapted (e.g., patient-specific and/or patient-engineered) implant components and one or more standard implant components.

Using patient-specific information and measurements, and selected parameters and parameter thresholds, an implant component, resection cut strategy, and/or guide tool can be selected (e.g., from a library) and/or designed (e.g., virtually designed and manufactured) to have one or more patient-adapted features. In certain embodiments, one or more features of an implant component (and, optionally, one or more features of a resection cut strategy and/or guide tool) are selected for a particular patient based on patient-specific data and desired parameter targets or thresholds. For example, an implant component or implant component features can be selected from a virtual library of implant components and/or component features to include one or more patient-specific features and/or optimized features for a particular patient. Alternatively or in addition, an implant component can be selected from an actual library of implant components to include one or more patient-specific features and/or optimized features for the particular patient.

In some embodiments, the process of selecting an implant component can also include selecting one or more component features that optimizes fit with another implant component. In particular, for an implant that includes a first implant component and a second implant component that engage, for example, at a joint interface, selection of the second implant component can include selecting a component having a surface that provides best fit to the engaging surface of the first implant component. For example, for a knee implant that includes a femoral implant component and a tibial implant component, one or both of the components can be selected based, at least in part, on the fit of the outer (e.g., joint-facing) surface with the outer surface of the other component. The fit assessment can include, for example, selecting one or both of the medial and lateral tibial grooves (e.g., joint-facing articular bearing surfaces) on the tibial component and/or one or both of the medial and lateral condyles on the femoral component that substantially negatively-matches the fit or optimizes engagement in one or more dimensions, for example, in the coronal and/or sagittal dimensions. For example, a surface shape of a non-metallic component that best matches the dimensions and shape of an opposing metallic or ceramic or other hard material suitable for an implant component. By performing this component matching, component wear can be reduced.

For example, if a metal backed tibial component is used with a polyethylene insert or if an all polyethylene tibial component is used, the polyethylene can have one or two curved portions typically designed to mate with the femoral component in a low friction form. This mating can be optimized by selecting a polyethylene insert that is optimized or achieves an optimal fit with regard to one or more of: depth of the concavity, width of the concavity, length of the concavity, radius or radii of curvature of the concavity, and/or distance between two (e.g., medial and lateral) concavities. For example, the distance between a medial tibial concavity and a lateral tibial concavity can be selected so that it matches or approximates the distance between a medial and a lateral implant condyle component.

Not only the distance between two concavities, but also the radius/radii of curvature can be selected or designed so that it best matches the radius/radii of curvature on the femoral component. A medial and a lateral femoral condyle and opposite tibial component(s) can have a single radius of curvature in one or more dimensions, e.g., a coronal plane. They can also have multiple radii of curvature. The radius or radii of curvature on the medial condyle and/or medial tibial component can be different from that/those on a lateral condyle and/or lateral tibial component.

In various embodiments, implant bearing surfaces can be patient-adapted by combining patient-specific with standard features. For example the bearing surface of a femoral implant can have a patient-specific curvature in one direction and a standard curvature in another direction. One way to construct such a bearing surface is to generate one or more patient-specific curves substantially in a first direction (e.g., substantially in the sagittal plane). These curves can be derived directly from the patient's 2D or 3D images such as CT or MRI scans or radiographs. The curves may also be constructed using measurements derived from the patient's anatomy, such as curvature radii or dimensions. In some embodiments, these curves may be refined or optimized (e.g., smoothed). Once the patient-specific curves for the first direction have been constructed, a set of standard cross section profile curves can be calculated in the second direction along the patient-specific curves (e.g., multiple curves essentially transverse to the sagittal curves). Each of the cross section profile curves can be the same. The curves can also be rotated with respect to each other. The standard properties of the cross section profile curves such as the curvature radius can change in a step by step fashion from profile to profile. The profile curves can consist of standard segments, e.g., segments with a standard curvature radius. Different segments may have different curvature radii. The segments can be convex or concave. They can be connected to form smooth transitions between the segments. Once the cross section profile curves have been defined, the bearing surface (e.g., joint-facing surfaces) can be constructed, for example using a sweep operation, wherein the cross section profile curves are moved along the paths of the patient-specific curves to form a continuous surface.

Furthermore, in select high flexion designs, one or more of the posterior condyle curvature, implant thickness, edge thickness, bone cut orientation, and bone cut depth, can be adapted to maximize flexion. For example, the posterior bone cut can be offset more anteriorly for a given minimum thickness of the implant. This anterior offsetting of the posterior cut can be combined with a taper of the posterior implant bearing surface. Other strategies to enhance a patient's deep knee flexion include adding or extending the implant component posteriorly, at the end bearing surface in high flexion. By extending the bearing surface the knee can be flexed more deeply. Accordingly, in certain embodiments, the posterior edge and/or posterior bearing surface is patient-engineered to enhance deep knee flexion for the particular patient. These designs can be accompanied by corresponding designs on the tibial plateau, for example by changing the posterior insert height or slope or curvature relative to the corresponding femoral radius on the posterior condyle.

Posterior Stabilized Articular Repair Systems

In addition to implant component features described above and in U.S. Patent Publication No. 2012-0209394, certain embodiments can include features associated with procedures that involve sacrificing one or more of the cruciate ligaments (e.g., the posterior cruciate ligament (PCL) and/or the anterior cruciate ligament (ACL)). For example, some embodiments may include features intended to function, at least in part, as a substitute for a patient's sacrificed PCL. Articular repair systems that include such features are commonly referred to as “posterior-stabilizing” (or “PS”) systems. Accordingly, features intended, at least in part, individually or collectively, to substitute for, and/or compensate for the lack of, a patient's PCL and/or ACL are referred to herein generally as “posterior stabilizing” features or elements.

Posterior stabilizing features can include, for example, an intercondylar box (which may also be referred to herein as a “housing” or “receptacle”) 4910, as shown in FIGS. 1A and 1B; an intercondylar cam (which may also be referred to herein as a “bar” or “keel”) 5010, 5012, as shown in FIGS. 2A and 2B; and a tibial post (which may also be referred to herein as a “projection” or “spine”) 5150. For example, as shown in FIGS. 2A and 2B, an intercondylar box and/or cam(s) of a femoral implant component may be configured to engage a post 5150 on a tibial implant component, which may thereby stabilize the joint through at least a portion of flexion or extension. Various embodiments of posterior stabilizing features and implant components are described in further detail below.

In various embodiments, an intercondylar box 4910 may be included in a femoral implant component, as shown, for example, in FIGS. 1A and 1B. The intercondylar box can comprise a variety of configurations, shapes, and dimensions. For example, in some embodiments, the box 4910 can include a proximal wall 4912, which forms a “closed” configuration box. Alternatively, in some embodiments the box 4910 may not have a proximal wall 4912, and thus, comprise an “open” box configuration. Furthermore, in some embodiments, the box can include one or more planar surfaces that are substantially parallel or perpendicular to one or more anatomical or biomechanical axes or planes. Additionally or alternatively, in some embodiments, the box can include one or more planar surfaces that are oblique in one, two, or three dimensions. Similarly, in some embodiments, the box can include one or more curved surfaces that are curved in one, two, or three dimensions. FIGS. 3L through 3P depict anterior-posterior or lateral views of cross-sections of the internal surfaces of several different box embodiments. As shown, for example, in FIG. 3L, in some embodiments the internal surfaces of the box may be symmetrical, while in other embodiments the internal surfaces may be asymmetrical. As discussed further below, various aspects of the configuration, shape, and/or dimensions of the box may be standard or patient adapted.

Additionally or alternatively, one or more intercondylar cams 5010, 5012 may be included in a femoral implant component, as shown, for example, in FIGS. 1B and 2B. Like the intercondylar box, intercondylar cams can comprise a variety of configurations, shapes, and dimensions. Some embodiments can include one cam, such as the femoral component shown in FIG. 1B, which includes only a posterior cam 5012. Other embodiments may include both an anterior cam 5010 and a posterior cam 5012. Some cams may be formed as independent structures extending between the medial and lateral condyle portions of the femoral implant, while other cams may be a portion of the femoral component forming a boundary of the intercondylar space, such as, for example, the edge of the femoral component forming the anterior boundary of the intercondylar space. In some embodiments, one or more cams may substantially comprise a cylindrical shape, including, for example, an elliptic, oblique, parabolic, or hyperbolic cylinder. In other embodiments, one or more cams may comprise irregular cross-sections, which can include one or more curvilinear and/or straight portions or sides. For example, FIGS. 4A-4R illustrate sagittal cross-sections of femoral components with exemplary cams 5012a-5012r. As shown, a femoral implant component can include a cam of a variety of shapes, sizes, and curvatures and one or more of these aspects can be patient adapted (i.e., patient-specific or patient-engineered). Exemplary methods of designing patient-adapted cams are described in detail below. Furthermore, while in some embodiments one or more cams may be symmetrical, one or more cams may also be asymmetrical. As discussed further below, various aspects of the configuration, shape, and/or dimensions of one or more cams may be standard or patient adapted.

In some embodiments, a box and/or cam(s) of the femoral component may be configured to engage a post 5150 projecting from a tibial implant component (e.g., tibial tray, polyethylene insert). The post can comprise a variety of configurations, shapes, and dimensions. In some embodiments, the post may be substantially straight and perpendicular to the tibial plateau. Alternatively, the tibial post can have a curvature or obliquity in one or more dimensions, which can optionally be, at least in part, mirrored by a corresponding surface of the box and/or cam(s). FIGS. 5A and 5B depict cross-sections in a medial-lateral plane of exemplary post embodiments. FIG. 5A shows (a) a tibial implant component with a substantially straight post and (b)-(d) tibial implant components having posts oriented laterally, with varying thicknesses, lengths, and curvatures. FIG. 5B shows (a)-(e) posts oriented medially, with varying thicknesses, lengths, and curvatures. Various post embodiments similarly include at least portions oriented posteriorly or anteriorly, with varying thicknesses, lengths, and curvatures. For example, some post embodiments include a generally posterior-facing surface substantially angled and/or curved posteriorly as it extends from the tibial component. Additionally or alternatively, some post embodiments can include a generally anterior-facing surface, which may be substantially angled and/or curved posteriorly as it extends from the tibial component. In some embodiments, the post can have a substantially concave posterior-facing surface 100a, as illustrated in FIG. 6A, showing a perspective view of a tibial component. Alternatively, some embodiments can include a substantially convex posterior-facing surface 100b, as illustrated in FIG. 6B, showing a superior view of a tibial component. A substantially concave posterior-facing surface can help facilitate M-L rotation of the post relative to a cam and/or box (e.g., external rotation during flexion). The post can optionally taper or can have different diameters and cross-sectional profiles, e.g., round, elliptical, ovoid, square, rectangular, at different heights from its base. As discussed further below, various aspects of the configuration, shape, and/or dimensions of the post may be standard and/or patient adapted.

The tibial post may be designed to engage the box and/or cam(s) of the femoral component in various configurations. In embodiments with a box comprising a proximal wall 4912, the post may be configured to engage at least a portion of the distal-facing surface of the proximal wall 4912. For example, one or more surfaces of the post (including portions facing generally superiorly, anteriorly, and/or posteriorly) may be configured to engage and, optionally, pivot upon and/or translate across a portion of the distal-facing surface of the box's proximal wall 4912. In some embodiments, the distal-facing surface of the proximal wall 4912 may be sloped and/or curved in one or more dimensions. In some embodiments, the distal-facing surface of the proximal wall 4912 may include at least a portion that is patient-adapted, for example, as described below.

In addition to, or in place of, engagement with the box, in some embodiments, the post may be configured to engage one or more cams. For example, one or more surfaces of the post facing generally posteriorly (e.g., surfaces 100a and 100b), may be configured to engage a posterior cam of the femoral component. The posterior cam may be configured to pivot upon and/or translate (e.g., inferiorly, superiorly, medially, and/or laterally) across, at least a portion of, a generally posterior-facing surface of the post through at least a portion of flexion and/or extension. Additionally and/or alternatively, one or more surfaces of the post facing anteriorly and/or superiorly, may be configured to engage an anterior cam of the femoral component. In some embodiments, the anterior cam may be configured to pivot upon and/or translate (e.g., inferiorly, superiorly, medially, and/or laterally) across a generally anterior-facing surface of the post through at least a portion of flexion and/or extension.

In some embodiments, one or more cams may further include a cam tongue (which may also be referred to herein as an “extension” or simply as a portion of the cam) extending from a portion of the cam, which may provide additional surface for engaging with the post through at least a portion of flexion and/or extension. For example, as shown in FIG. 7A, cam 5012s can include a cam tongue 105a extending generally posteriorly. Cam tongues can provide additional length and/or area of cam surface for engaging a post, which can, for example, functionally increase the jump-height of an implant configuration, facilitate cam-post engagement in deep flexion, and/or accommodate distribution of loading and forces between the cam and post over larger surface area(s). FIGS. 7B-7C illustrate sagittal cross-sections of an exemplary femoral component embodiment with a cam tongue 105b configured for engaging an exemplary tibial post 5150 at multiple angles of flexion (e.g., FIG. 7B, 7C). FIGS. 7D-7F illustrate sagittal cross-sections of additional femoral component embodiments with additional cam tongue configurations 105c-105e configured for engaging an exemplary tibial post 5150. As shown, a variety of configurations can be utilized and any one or more of the shape, size, and/or curvature of the cam, cam tongue, and/or post can be patient adapted (i.e., patient-specific or patient-engineered).

Additionally and/or alternatively, in some embodiments, the post can be configured to slide within a groove in a box and/or cam of the femoral implant. The groove may extend along a portion or substantially the entire anterior-posterior length of the box. In some embodiments, the groove can comprise stopping mechanisms at each end of the groove to prevent the post from dislocating from the track of the groove. The groove may have a width that extends across only a portion or substantially the entirety of the M-L box width. In some embodiments, the groove width may vary along the A-P length of the box.

In some embodiments, the post, box, and/or cam(s) may be configured to allow M-L rotation of the femoral component relative to the tibial component through at least a portion of flexion and/or extension. For example, in some embodiments, the cross-section of the portion of the post received by the box may be sufficiently smaller than the width of the box to allow M-L rotation of the post within the box. In some embodiments, the superior end of the post and/or a surface of the post that engages the box and/or cam(s) may be shaped to facilitate rotation and/or pivoting. For example, the superior end of the post and/or a surface of the post that engages the box and/or cam(s), or one or more portions thereof, may by substantially rounded, semi-spherical, or semi-cylindrical.

In some embodiments, the post, box, and/or cam(s) may be configured to guide and/or force M-L rotation of the femoral component relative to the tibial component through at least a portion of flexion and/or extension. For example, one or more surfaces of the post, box, and/or cam(s) may be sloped and/or curved (e.g., medially, laterally, anteriorly, posteriorly) over at least a portion of the surface that engages with the opposing post, box, and/or cam(s). By way of example, the anterior-facing and/or posterior-facing surfaces of the post may be sloped and/or curved so as to guide and/or force M-L rotation as that portion of the post engages, pivots upon, and/or translates across the box and/or cam(s). Similarly, the distal-facing surface of the proximal wall 4912 of the box and/or one or more cam surfaces may be sloped and/or curved so as to guide and/or force M-L rotation as the post engages, pivots upon, and/or translates across that box and/or cam surface.

Furthermore, in some embodiments, the slope and/or curvature of one or more surfaces of the post, box, and/or cam(s) may vary along one or more dimensions of the post, box, and/or cam(s). For example, an engagement surface's slope and/or curvature may vary (e.g., medially, laterally, anteriorly, posteriorly) along, at least a portion of, the length and/or width of the post, box, and/or cam(s). In some embodiments, this slope and/or curvature may increase in the direction along which the surface is engaged as flexion increases. For example, in some embodiments, a posterior cam may be configured to engage a posterior surface of a post, traversing the post in a generally inferior direction as flexion increases, and the post's posterior surface's slope and/or curvature with respect to an M-L axis may increase in the inferior direction, which can guide or force greater M-L rotation with greater flexion. Similarly, the slope and/or curvature with respect to an M-L axis of one or more surfaces of a cam may increase in the direction/order along which the one or more surfaces engage the post during flexion. In some embodiments, the slope and/or curvature of one engagement surface (e.g., the post's posterior surface) may substantially mirror the slope and/or curvature of the opposing engagement surface (e.g., the posterior cam surface that engages the post's posterior surface). As discussed further below, the slope and/or curvature of one or more surfaces of the post, box, and/or cam(s) may be standard or patient adapted.

In various embodiments, the post, box, and/or cam(s) can include features that are patient-adapted (e.g., patient-specific or patient-engineered). For example, one or more of the configurations, shapes, dimensions, slopes, curvatures, and/or positions of the post, box, and/or cams may be patient-adapted. Accordingly, one or more features of posterior-stabilizing implant components of various embodiments herein can be designed and/or selected, based, at least in part, on patient-specific data, including, for example, one or more of: intercondylar distance or depth; femoral shape; condyle shape; M-L length of femur (e.g., from medial-most point of medial epicondyle to lateral-most point of lateral epicondyle), tibial plateau, medial and/or lateral femoral condyle, medial and/or lateral tibial plateau; A-P length of femur (e.g., from anterior-most point of distal femur to posterior-most point of medial or lateral femoral condyle), tibial plateau, medial and/or lateral femoral condyle, medial and/or lateral tibial plateau; lateral and/or medial tibial plateau slope, convexity/concavity, A-P length, M-L length, offset; lateral and/or medial tibial spine locations; ACL, PCL, MCL, and/or LCL origin location, insertion location, orientation, or physical or force direction; and one or more of the parameters listed in Table 3 and/or Table 4 below. Moreover, in some embodiments, one or more dimensions of the post, box, and/or cam(s) can be designed and/or selected based, at least in part, on patient-specific information to avoid patellar surface impingement.

Additionally or alternatively, other patient characteristics can also be utilized, including, for example, weight, height, sex, bone size, body mass index, muscle mass; and/or any other patient-specific information described herein. Alternatively or in addition, one or more features of the post, box, and/or cam(s) can be engineered based on patient-specific data and, optionally, additional data, such as, for example, implant component material properties and/or desired kinematic properties (obtained from, e.g., population database, biomotion modeling, clinical studies), manufacturing requirements/limitations. For example, the dimensions of the post, box, and/or cam(s) can be designed and/or selected based on a minimum allowable thickness determined based on one or more of the material properties of the post, box, and/or cam(s) and the patient's weight, height, sex, bone size, body mass index, and/or muscle mass.

Accordingly, in some embodiments, various dimensions of the post, box and/or cam(s) can be designed and/or selected based, at least in part, on various patient dimensions and/or implant dimensions. Examples of embodiments are provided in Table 1. These examples are in no way meant to be limiting.

TABLE 1
Exemplary Embodiments of Box and/or Cam Dimensions
Based on Patient-Specific Anatomical Dimensions
Post, Box,
and/or Cam
Dimension       Corresponding Patient Anatomical Dimension
Mediolateral    Maximum mediolateral width of patient intercondylar
width           notch or fraction thereof
Mediolateral    Average mediolateral width of intercondylar notch
width
Mediolateral    Median mediolateral width of intercondylar notch
width
Mediolateral    Mediolateral width of intercondylar notch in select
width           regions, e.g., most inferior zone, most posterior
                zone, superior one third zone, mid zone, etc.
Superoinferior  Maximum superoinferior height of patient intercondylar
height          notch or fraction thereof
Superoinferior  Average superoinferior height of intercondylar notch
height
Superoinferior  Median superoinferior height of intercondylar notch
height
Superoinferior  Superoinferior height of intercondylar notch in select
height          regions, e.g., most medial zone, most lateral zone, central
                zone, etc.
Anteroposterior Maximum anteroposterior length of patient intercondylar
length          notch or fraction thereof
Anteroposterior Average anteroposterior length of intercondylar notch
length
Anteroposterior Median anteroposterior length of intercondylar notch
length
Anteroposterior Anteroposterior length of intercondylar notch in select
length          regions, e.g., most anterior zone, most posterior zone,
                central zone, anterior one third zone, posterior one third
                zone etc.

FIGS. 3A through 3P show various exemplary embodiments of an intercondylar box. FIG. 3A shows a box height adapted to the superoinferior height of the intercondylar notch. The dotted outlines indicate portions of the bearing surface and posterior condylar surface as well as the distal cut of the implant. FIG. 3B shows a design in which a higher intercondylar notch space is filled with a higher box, for example, for a wide intercondylar notch. FIG. 3C shows a design in which a wide intercondylar notch is filled with a wide box. The mediolateral width of the box is selected and/or designed based on the wide intercondylar notch. FIG. 3D shows an example of an implant component having a box designed for a narrow intercondylar notch. The mediolateral width of the box is selected and/or designed for the narrow intercondylar notch. FIG. 3E shows an example of an implant component having a box for a normal size intercondylar notch. The box is selected and/or designed for its dimensions. (Notch outline: dashed and stippled line; implant outline: dashed lines). FIG. 3F shows an example of an implant component for a long intercondylar notch. The box is designed, adapted or selected for its dimensions (only box, not entire implant shown).

FIG. 3G is an example of one or more oblique walls that the box can have in order to improve the fit to the intercondylar notch. FIG. 3H is an example of a combination of curved and oblique walls that the box can have in order to improve the fit to the intercondylar notch. FIG. 3I is an example of a curved box design in the A-P direction in order to improve the fit to the intercondylar notch. FIG. 3J is an example of a curved design in the M-L direction that the box can have in order to improve the fit to the intercondylar notch. Curved designs are possible in any desired direction and in combination with any planar or oblique planar surfaces. FIG. 3K is an example of oblique and curved surfaces in order to improve the fit to the intercondylar notch. Alternatively or additionally, the box can form an opening having a generally longitudinal axis extending at an angle relative to a sagittal plane. In some such embodiments, either or both of the medial and lateral walls (including one or more bone-facing surfaces and/or one or more intercondylar facing surfaces) of the box may be angled relative to a sagittal plane. In some embodiments, one or more of such angles relative to a sagittal plane may be based on patient-specific information, including, for example, any of the parameters listed in Tables 3 and 4 below.

In various embodiments, preparation of an implantation site for a posterior stabilizing implant can include the use of one or more patient-adapted surgical techniques, cutting guides, and/or instruments. Such surgical techniques, cutting guides, and/or instruments can include, for example, any of those described in U.S. Patent Publication No. 2012-0209394, including those discussed for use in non-posterior-stabilizing techniques (e.g., cruciate retaining techniques). For example, as an initial step in guiding a surgeon for preparation of the femur for the implantation of a patient-adapted femoral implant, a femoral jig 18000, as illustrated in FIG. 8. can be used to, for example, align and locate guide pins (i.e., Steinman Pins) for placing various jigs used for aligning subsequent femoral cuts. This jig 18000 can incorporate an inner surface (not shown) that substantially conforms to some or all of the outer surface of the uncut distal femur 18001 (e.g., cartilage and/or subchondral bone), whereby the jig fits onto the femur in desirably only one position and orientation. In various embodiments, the jig 18000 can comprise a flexible material which allows the jig 18000 to flex and “snap fit” around the distal femur. In addition, the inner surface of the jig can be intentionally designed to avoid and/or accommodate the presence of osteophytes and other anatomical structures on the femur 18001. A pair of pin openings 18010, extending through the surface of the jig, can provide position and orientation guidance for a pair of guide pins that can be inserted into the distal surface of the femur (not shown). The jig 18000 can then be removed from the femur 18001 and subsequent steps for preparing the femur can be performed (e.g., placement of one or more bone cuts corresponding to the bone-facing surfaces of the patient-adapted femoral implant), optionally, utilizing and/or referencing the position and/or orientation of the guide pins.

Additionally or alternatively, some embodiments may include the use of, for example, a patient-adapted cutting guide configured for guiding one or more femoral box cuts. For example, some embodiments can include a femoral box-cut guide 120 as depicted in FIG. 9. Such a cutting guide may be derived, generally, for example, from the design for a patient-adapted femoral implant. Accordingly, in some embodiments, one or more bone-facing surfaces 30 of the cut guide may be configured to engage one or more bone cuts planned for the femoral implant. In some embodiments, one or more bone facing surfaces of the femoral box-cut guide may be configured to engage uncut bone and/or cartilage, based, for example, on patient-specific information. The femoral box-cut guide 120 can include one or more box-cut guide surfaces 140. One or more of the box-cut guide surfaces 140 can include one or more features (e.g., position, shape, size, curvature, slope) based, at least in part, on patient-specific information. Additionally, in some embodiments, a femoral box-cut guide 120 can include one or more pin holes 150, which may be patient adapted, and which may facilitate stabilization of the guide and/or referencing other cutting guides and/or drilling instruments.

As discussed above, in various embodiments, the length, width, height, orientation, slope and/or curvature of one or more portions of the post, box, and/or cam(s) can be designed and/or selected to be patient-adapted based on patient-specific information. In some embodiments, one or more shapes and/or curvatures of at least a portion of the post may be patient-adapted. For example, in some embodiments, a position and/or curvature of the post may be designed to allow and/or guide a desired amount of external rotation and/or posterior-lateral rollback based on a difference in anterior-posterior dimension between the medial and lateral compartments, for example, as depicted in FIG. 10. For example, a degree of angular shift B of post 5150a may be determined based on the length difference A between the medial and lateral compartments.

In some embodiments, one or more features of the post, box, and/or cam(s) may be based on at least a portion of one or more patient-specific femoral sagittal curvatures, lines, and/or angles (e.g., troclear J-curve, medial condylar J-curve, lateral condylar J-curve, Blumensaat line, and/or curvature of the roof of the intercondylar notch) derived, for example, as disclosed in U.S. Patent Publication No. 2012-0209394. For example, FIG. 11 depicts a sagittal cross-sectional view of an embodiment in which the distal-facing surface 180 of the box proximal wall 4912 includes a sagittal curvature correlated to the changing centers of curvature of the femoral condyles. Similarly, in some embodiments, one or more edges and/or surfaces of the post may be selected and/or designed based on at least a portion (e.g., anterior, distal, proximal, or combinations and/or portions thereof) of one or more femoral sagittal curvatures, lines, and/or angles. For example, FIG. 12a depicts an exemplary embodiment of a post 5150c, having a lateral posterior edge portion 190 and a medial posterior edge portion 200. The shape and/or curvature of one or both of the medial and lateral posterior edge portions 190, 200 can be based on one more patient-specific sagittal curvatures, lines, and/or angles (or portions thereof). For example, a shape of a lateral posterior edge portion 190 can based on a posterior portion of a lateral femoral J-curve, while a shape of medial posterior edge portion 200 can be based on a posterior portion of a medial femoral J-curve. Accordingly, such a patient-specific post can have varying cross-sections, for example, as illustrated in FIG. 12b, showing transverse cross-sections of post 5150c relative to lines a′, b′, c′, and d′ in FIG. 12a. Note, in various embodiments, the edge portions of the post referred to herein may comprise substantially sharp edges and/or substantially curved, chamfered, or rounded edges.

As mentioned above, in some embodiments, one or more features of the post, box, and/or cam(s) may be based on a portion (e.g., anterior, distal, proximal, or combinations and/or portions thereof) of one or more femoral sagittal curvatures, lines, and/or angles. For example, in some embodiments, a post curvature may be based on a portion of a posterior femoral J-curve. Additionally and/or alternatively, in some embodiments, particular portion(s) and/or relative angle(s) of the one or more curvatures, lines, and/or angles, can be determined based, for example, on its location and/or orientation during one or more portions of flexion, extension, and/or engagement of the post and box/cam. For example, in some embodiments, the portion of a condylar J-curve contacting a tibial surface at the same time contact first occurs between the cam and post may be used to derive a feature of the post, box, and/or cam(s). Similarly, in some embodiments, a shape and/or position of a post and/or cam can be determined based on the angle of the Blumensaat line relative to an anatomical axis at varying degrees of flexion, extension, and/or engagement of the post and box/cam. A shape and/or position of multiple positions of the post and box/cam can each be based on the particular angle of the Blumensaat line relative to an anatomical axis when desired and/or modeled engagement occurs between the post and box/cam at the respective positions.

Furthermore, as will be appreciated, the particular relationship between one of the exemplary patient-specific parameters discussed herein (e.g., any discussed above and/or listed in Table 2, 3, and/or 4 below) and a posterior-stabilizing feature (or other implant feature) can comprises a variety of forms in addition to direct matching. For example, in some embodiments, a mathematical function (e.g., linear, non-linear) may be used to correlate a patient-specific anatomical parameter (e.g., dimension, curvature) to a post, box, and/or cam parameter. Additionally or alternatively, in some embodiments, simulations (e.g., kinematic and/or non-kinematic modeling) may be used derive a relationship to be used for selecting and/or designing a given posterior stabilizing feature based on patient-specific parameters.

In various embodiments, as illustrated for example in FIG. 28, a box width 402 of a femoral implant design 404a may be based, at least in part, on patient-specific information. Likewise, in some embodiments, a box-wall thickness 406 (e.g., minimum, uniform, maximum thickness) may be based, at least in part, on patient-specific information. Further, in some embodiments, a post 408a of a tibial component 410a may have a substantially circular cross-section in a transverse plane with a radius 412 that may also be based, at least in part, on patient-specific information. In some embodiments, the position of post 408a may be determined such that post 408a is substantially mediolaterally centered within the box. Similarly, in some embodiments, an anterior termination point 416 of the box may be determined, at least in part, by the A-P position of post 408a. Furthermore, with reference to FIG. 29, at least in some embodiments, a femoral implant design 404b may include a cam 418a and cam arms 420a that connect cam 418a to box walls 422. A thickness of cam 418a and/or of cam arms 420a may be based, at least in part, on patient-specific information. Additionally, a radius or radii of curvature of a sweep 424 of cam 418a and/or sweep 426 of cam arms 420, at one or more locations (e.g., D1, D2), may be based, at least in part, on patient-specific information.

In some embodiments, one or more of box width 402, box-wall thickness 406, radius 412 of post 408a, thickness of cam 418a and/or of cam arms 420a, and/or radius or radii of curvature of sweep 424 of cam 418a and/or sweep 426 of cam arms 420 may be derived, at least in part, from a patient-specific, measured M-L length of the femur (e.g., from medial-most point of medial epicondyle to lateral-most point of lateral epicondyle) and, optionally, be bounded by minimum and/or maximum design values. At least in some cases, utilizing the M-L length of the patient's femur may help ensure the respective features are sufficiently strong for the given patient because the M-L length can provide a correspondence with an estimated weight of the patient (e.g., based on data from clinical studies).

In some embodiments, one or more jump heights associated with the implant components may be based, at least in part, on patient-specific information. For example, with reference to FIG. 30, a post-cam jump height may be defined by the maximum distance 430 between the base of a cam 418b of a femoral component 404c and the top of a post 408b of a tibial component 410b, when femoral component 404c and tibial component 410b are positioned at about a maximum flexion angle (e.g., about 100, about 110, about 120, about 130, about 140 degrees of flexion). At least in some embodiments, the distance 430, corresponding to the post-cam jump height, may be derived based, at least in part, on patient-specific information. Accordingly, in some such embodiments, one or more features of femoral component 404c and/or tibial component 410b (e.g., one or more aspects of a femoral articular surface, a tibial articular surface, cam 418b, and/or post 408b) may be selected and/or designed to achieve (at a minimum) the derived jump-height distance. Alternatively or in addition, one or more anterior and/or posterior jump heights of a medial articular surface 432 and/or lateral articular surface 434 of a tibial component 410c may be based, at least in part, on patient-specific information. In some embodiments, for example, the posterior jump heights may be derived based on an M-L length of the tibial plateau, and the relationships may be such that the posterior medial articular surface will have a larger jump height and/or be more conforming to the corresponding femoral articular surface than the posterior lateral articular surface.

In various embodiments, a patella-tendon relief 438 of a tibial component 410c may be based, at least in part, on patient specific information. For example, as illustrated in FIG. 32, the position, size, and/or shape of the tibial tubercle 442 of the tibia 440 may be determined. Patella-tendon relief 438 (e.g., as illustrated in FIG. 31) may then be positioned based on (e.g., substantially aligned with) the tibial tubercle 442. In addition, a cut-depth and/or height of the patella-tendon relief 438 may, optionally, be derived, at least in part, from a medial A-P length of the tibia 440 and/or tibial component 410c.

As noted above, in various embodiments, a patient-adapted simulation can be used in selecting and/or designing one or more of the implant component parameters discussed herein. While one or more such parameters may be selected and/or designed starting from such a simulation, one or more parameters may also have initial standard or patient-adapted values (e.g., as defined elsewhere herein), which may then be modified and/or refined based, at least in part, on the patient-specific simulation. In some cases, refinements may be accomplished through an iterative process of modifying one or more parameters and then re-evaluating in the simulation.

In some embodiments, for example, a simulation can begin with modeling articular surfaces of femoral and/or tibial components, substantially based, for example, on a cruciate-retaining design (e.g., as disclosed in U.S. Patent Publication No. 2012-0209394). Optionally, a starting cruciate-retaining design may be modified by, for example, increasing the posterior resections of the femoral condyle. Also, optionally, in some embodiments, one or more posterior-stabilizing features (or portions thereof) based on initial standard or patient-adapted values may be incorporated into the cruciate-retaining design. Next, varying predictiles can be created by modeling the components in engagement at varying degrees of flexion/extension. Relative locations (and/or required adjustments thereto) of features (e.g., length, width, height, orientation, slope and/or curvature) of portions of a proposed box, post, cam(s), and/or cam arms can be determined based on one or more of the predictiles. Optionally, additional standard and/or patient-specific parameters may also be utilized in such simulations. For example, in some embodiments, a desired angle of flexion at which post and box/cam engagement begins can be set (e.g., at about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, or about 100 degrees of flexion). Additionally or alternatively, a desired maximum flexion angle may also be set (e.g., at about 110, about 115, about 120, about 125, about 130, about 135, about 140, about 145, about 150, about 155, or about 160 degrees of flexion). These exemplary flexion angle parameters may be patient specific or standard in various embodiments.

In certain embodiments, one or more of a box, post, cam(s), and/or cam arms (or portions thereof) may be selected, designed, and/or modified based on modeling engagement of a femoral implant component (e.g., any of the patient-adapted femoral implant components disclosed herein) and a tibial implant component (e.g., any of the patient-adapted femoral implant components disclosed herein) through one or more degrees of flexion and/or extension. For example, in some embodiments, a cam may be centered on or about the mid-thickness of the condyle. This may be determined by deriving a circle 305 best-fit to a portion (e.g., posterior) of the sagittal curvature 308 of the implant condyle shape, as illustrated in FIG. 16. The midpoint 310 of the condylar thickness 312 may be determined at one of the chamfer corners, as shown in FIG. 17, and a circle 314 may then be created using the center point 313 of circle 305 and extending out to midpoint 310. Next, in some embodiments, the femoral component may be positioned with its sagittal plane aligned with the tibial component's sagittal plane and at a starting flexion angle (e.g., at about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, or about 100 degrees of flexion) for modeling.

In some modeling embodiments, the initial flexion angle may be set at about 60°. Additionally, in some embodiments, the components may be further positioned such that a particular femoral bearing point (e.g., inferior-most point of condylar surface, i.e., joint-facing surface, at the given flexion angle) is aligned with a particular tibial bearing point (e.g., inferior-most point of a tibial articulating surface, i.e., joint-facing surface). With the component positions set, a circle 316a may be derived that is tangent to a post bearing surface 318 and centered on circle 314, as illustrated in FIG. 18. Then, in some embodiments, the sagittal planes of the femoral and tibial components may be realigned, if needed, the flexion angle may be adjusted, and the steps described above may be repeated one or more times at varying angles of flexion to derive corresponding circles 316. For example, FIG. 19 illustrates a circle 316b derived at 75° and FIG. 20 illustrates a circle 316c derived at 90°.

Optionally, in some embodiments, at one or more flexion angles, the relative positions of the particular femoral bearing point and particular tibial bearing point may be adjusted (e.g., to account for femoral rollback on the tibia). For example, in FIG. 21, the flexion angle is set at 120°, and the particular femoral bearing point (e.g., inferior-most point of condylar surface at the given flexion angle) is positioned 3 mm posterior to the particular tibial bearing point (e.g., inferior-most point of a tibial articulating surface). Then, as described above, a circle 316d may be derived. The flexion angles at which relative positions of the bearing points are adjusted, as well as the amount and direction may be based on a variety of factors, including, for example, any of the patients-specific parameters described herein (e.g., in Tables 3 and 4) and/or generalized information regarding joint kinematics (e.g., clinical studies). For example, in some embodiments, one or more of the flexion angles at which relative positions of the bearing points are adjusted, the amount of adjustment, and the direction of adjustment may be derived on generalized kinematic information correlating femoral rollback and/or femoral rotation to one or more patient-specific parameters (e.g., height, weight, femoral width (M-L length of the femur)).

Furthermore, in some embodiments of the modeling methods above, each of the derived circles 316a-d may be mapped into one view and an arc 320 may be created using the circles 316a-d as a guide for a peripheral arc of curvature, as shown in FIG. 22. FIG. 23 shows resultant cam extrusion 322 at 60° and FIG. 24 shows the cam extrusion 322 at 120°. Optionally, additional modifications can be made to the cam 322 to, for example, increase jump-height and/or optimize point loading and/or surface forces between the cam and post. For example, FIG. 25 illustrates extending 330 the cam to maximize the contact area at 120° of flexion. Similarly, FIG. 26 illustrates extending 340 the cam to maximize the contact area at 60° of flexion. FIG. 27a illustrates identifying an angle at which contact area 342 is at the lowest, and FIG. 27b illustrates modifying the cam by rounding 344 the cam surface around point 342 to optimize the contact area. Alternatively or in addition, in some embodiments, a length of the cam may be defined such that a particular desired clearance (e.g., about 3 mm) is provided between the cam and the tibial tray when positioned at about a maximum flexion angle (e.g., about 100, about 110, about 120, about 130, about 140 degrees of flexion) to avoid subluxation of the femur.

It will be appreciated that while a single cross-sectional shape of the post is depicted in FIGS. 17-27b and its bearing surface 318 is angled posteriorly as it extends superiorly, various post sizes, shapes, and positions (e.g., any disclosed elsewhere herein) could be utilized in such a simulation. In some embodiments, for example as illustrated in FIG. 33, a post 408c having a posterior bearing surface that is substantially perpendicular to the proximal tibial cut plane may be utilized. In some embodiments, the location of the post can be selected and/or designed, at least in part, to provide for one or more minimum clearances relative to the cam. For example, the relative anterior-posterior position of the post may be determined to provide a minimum clearance relative to the cam at one or more flexion angles (e.g., at about 70, about 80, about 90, about 100, about 110, about 120, about 130 degrees of flexion). In some embodiments, a medial-lateral center of the post may be aligned substantially within a sagittal plane of the knee joint.

Alternatively or in addition, the relative positions of the post and box may be assessed at one or more flexion angles (e.g., about −12, about 90, and about 120 degrees flexion) to identify any interference between the two features and if interference is identified, modify one or more component parameters to eliminate the interference. By way of example, as illustrated in FIG. 33, the femoral component 404d and tibial component 410d may be positioned in a hyper-extension angle (e.g., about 12 degrees of hyper-extension), and it may be confirmed that there is no interference between post 408c and the perimeter of the box (e.g., including termination plane 440 of the box). Alternatively or in addition, it may be confirmed that termination plane 440 of the box is sufficient to accommodate a minimum desired clearance of the cam arm 420b to terminate on the width of the box wall 442.

Similarly, in some embodiments, the relative positions of the cam and post may be assessed at a maximum flexion angle (e.g., about 100, about 110, about 120, about 130, about 140 degrees of flexion) to determine if a desired and/or minimum cam-post jump height is present. If not, one more component parameters may then be modified to achieve the desired cam-post jump height.

Additionally or alternatively, one or more features of the post, box, and/or cam(s) may be based on patient-specific and/or desired kinematic properties, including, for example, M-L rotation, femoral rollback, and/or any one or more of the other exemplary parameters listing in Table 3 below. For example, as discussed above, in some embodiments, one or more surfaces of the post, box, and/or cam(s) may be sloped and/or curved (e.g., medially, laterally, anteriorly, posteriorly) over at least a portion of the surface that engages with the opposing post, box, and/or cam(s) in order to guide and/or force M-L rotation (e.g., femoral external rotation) of the femoral component relative to the tibial component and femoral rollback (e.g., lateral femoral rollback). Accordingly, in some embodiments, the nature and degree of the slope and/or curvature of the one or more surfaces of the post, box, and/or cam(s) may be based on a patient-specific and/or desired M-L rotation and rollback.

In various embodiments, patient-specific ligament (e.g., ACL, PCL, MCL, LCL) information (e.g., origin location, insertion location, orientation, physical or force direction), may be used to select and/or design posterior stabilizing features. In some embodiments, such ligament information may be derived from kinematic information (e.g., from measured patient-specific information or from modeling based on average kinematics for a particular relevant population group). Additionally or alternatively, in some embodiments, such ligament information may be obtained from bony landmarks (e.g., based on directly measured patient-specific locations or based on locations derived from information correlating average locations to other measurable patient-specific information). Optionally, in certain embodiments, such ligament information may also be obtained directly from soft-tissue imaging of the patient.

In some embodiments, the post can slope and/or curve medially, laterally, anteriorly, and/or posteriorly as it extends from its base to its tip, as discussed above and as depicted, for example, in FIGS. 5A and 5B. The anterior surface of the post, posterior surface of the post, or both may be patient-adapted. For example, the M-L and/or A-P slope and/or curve of the anterior and/or posterior surface of the post can be patient-derived or patient-matched (e.g., to match the physical or force direction of the PCL or ACL). Further, in some embodiments, the sagittal curve of one or more surfaces of the post can be based on the PCL location and orientation or combinations of ACL and PCL location and orientation. In some embodiments, the shape of one or more surfaces of the post may be patient-adapted (in, e.g., the sagittal plane) to optimize rollback for the particular patient. Desired rollback may be modeled based on, for example, the dimensions of the patient's tibial plateau, e.g., A-P dimension and/or M-L dimension, oblique dimension, and/or combinations thereof. In some embodiments, one or more sagittal dimensions, slopes, and/or curvatures of the post may be based on and/or proportional to an A-P length (e.g., average A-P length) of the patient's tibial plateau. For example, the post depicted in FIG. 13A may be appropriate for a patient with a relatively smaller tibial plateau A-P length, while the post depicted in FIG. 13B, extending further posteriorly, may be appropriate for a patient with a relatively larger tibial plateau A-P length.

Further examples of patient dimensions and/or implant dimensions upon which corresponding post dimensions can be based, at least in part, in some embodiments are provided in Table 2. These examples are in no way meant to be limiting.

TABLE 2
Exemplary Embodiments of Post Dimensions Based
on Patient-Specific Anatomical Dimensions
Post Dimension  Corresponding Patient Anatomical Dimension
Mediolateral    Maximum mediolateral width of patient intercondylar
width           notch or fraction thereof
Mediolateral    Average mediolateral width of intercondylar notch
width
Mediolateral    Median mediolateral width of intercondylar notch
width
Mediolateral    Mediolateral width of intercondylar notch in select
width           regions, e.g. most inferior zone, most posterior zone,
                superior one third zone, mid zone, etc.
Superoinferior  Maximum superoinferior height of patient intercondylar
height          notch or fraction thereof
Superoinferior  Average superoinferior height of intercondylar notch
height
Superoinferior  Median superoinferior height of intercondylar notch
height
Superoinferior  Superoinferior height of intercondylar notch in select
height          regions, e.g. most medial zone, most lateral zone, central
                zone, etc.
Anteroposterior Maximum anteroposterior length of patient intercondylar
length          notch or fraction thereof
Anteroposterior Average anteroposterior length of intercondylar notch
length
Anteroposterior Median anteroposterior length of intercondylar notch
length
Anteroposterior Anteroposterior length of intercondylar notch in select
length          regions, e.g. most anterior zone, most posterior zone,
                central zone, anterior one third zone, posterior one third
                zone etc.

In some embodiments, the position of the post can be adapted based on patient-specific dimensions. For example, the post can be matched with or adapted relative to or selected based on the position or orientation of the ACL or the PCL origin and/or insertion. Alternatively, the post can be placed at a predefined distance from the ACL and/or PCL insertion, from the medial or lateral tibial spines, or from other bony or cartilaginous landmarks or sites. The position of the post can be matched with or adapted relative to or selected based on anatomical dimensions or landmarks, such as, for example, a femoral condyle shape, a notch shape, a notch width, a femoral condyle dimension, a notch dimension, a tibial spine shape, a tibial spine dimension, a tibial plateau dimension, and/or an ACL, PCL, MCL, and/or LCL origin or insertion location.

Similarly, the position of the box and/or cam(s) on the femoral component can be designed, adapted, or selected to be close to the PCL origin or insertion or at a predetermined distance to the PCL or ACL origin or insertion or other bony or anatomical landmark. The position of the box and/or cam(s) can be matched with or adapted relative to or selected based on anatomical landmarks or dimensions, e.g., a femoral condyle shape, a notch shape, a notch width, a femoral condyle dimension, a notch dimension, a tibial spine shape, a tibial spine dimension, a tibial plateau dimension, and/or an ACL, PCL, MCL, and/or LCL origin or insertion location.

In addition to the various patient-adapted configurations and corresponding parameters described above, one or more features of the post, box, and/or cam(s) may be adapted based on additional parameters, such as, for example, those discussed and listed below in Table 4 and/or parameters obtained through patient-specific and/or generalized biomotion models. For example, in some embodiments, the length, width, height, orientation, slope, curvature, and/or position of the post, box, and/or cam(s) may be selected and/or designed based on one or more of the exemplary parameters listed in Table 3. These examples are in no way meant to be limiting.

TABLE 3
Parameters measured in a patient-specific biomotion model
Medial femoral rollback during flexion
Lateral femoral rollback during flexion
Patellar position, medial, lateral, superior, inferior for different flexion
and extension angles
Internal and external rotation of one or more femoral condyles
Internal and external rotation of the tibia
Flexion and extension angles of one or more articular surfaces
Anterior slide and posterior slide of at least one of the medial and
lateral femoral condyles during flexion or extension
Medial and lateral laxity throughout the range of motion
Contact pressure or forces on at least one or more articular surfaces,
e.g., a femoral condyle and a tibial plateau, a trochlea and a patella
Contact area on at least one or more articular surfaces, e.g. a femoral
condyle and a tibial plateau, a trochlea and a patella
Forces between the bone-facing surface of the implant, an optional
cement interface and the adjacent bone or bone marrow, measured at
least one or multiple bone cut or bone-facing surface of the implant on
at least one or multiple articular surfaces or implant components.
Ligament location, e.g., ACL, PCL, MCL, LCL, retinacula, joint
capsule, estimated or derived, for example using an imaging test.
Ligament tension, strain, shear force, estimated failure forces, loads
for example for different angles of flexion, extension, rotation,
abduction, adduction, with the different positions or movements
optionally simulated in a virtual environment.
Adduction/abduction moments, flexion/extension moments, internal/
external rotation moments
Potential implant impingement on other articular structures, e.g. in high
flexion, high extension, internal or external rotation, abduction or
adduction or any combinations thereof or other angles/positions/
movements.

Additionally or alternatively, in some embodiments, the dimensions of the post, box, and/or cam(s) can be selected and/or designed based, at least in part, on the intended implantation technique, or properties thereof, such as, for example intended flexion, rotation, and/or tibial slope. For example, at least one of an anteroposterior length or superoinferior height can be adjusted if an implant is intended to be implanted in 7 degrees flexion as compared to 0 degrees flexion, reflecting the relative change in patient or trochlear or intercondylar notch or femoral geometry when the femoral component is implanted in flexion.

In another example, the M-L width can be adjusted if an implant is intended to be implanted in internal or external rotation, reflecting, for example, an effective elongation of the intercondylar dimensions when a rotated implantation approach is chosen. The post, box, and/or cam(s) can include oblique or curved surfaces, typically reflecting an obliquity or curvature of the patient's anatomy. For example, the superior portion of the box and/or cam(s) can be curved reflecting the curvature of the intercondylar roof. In another example, at least one side wall of the box can be oblique reflecting an obliquity of one or more condylar walls.

The posterior stabilizing features described above may be integrally formed with other components of the articular repair system or may be modular. For example, in certain embodiments, the femoral implant component can be designed and manufactured to include a box and/or cam as a permanently integrated feature of the implant component. Alternatively, in certain embodiments, a box and/or cam can be modular. For example, the box and/or cam can be designed and/or manufactured separate from the femoral implant component and optionally joined with the component, either prior to (e.g., preoperatively) or during the implant procedure. Methods for joining a modular box to an implant component are described in the art, for example, in U.S. Pat. No. 4,950,298. In some embodiments disclosed herein, modular cams can be joined to an implant component at the option of the surgeon or practitioner, for example, using spring-loaded pins at one or both ends of the modular cams. The spring-loaded pins can slideably engage corresponding holes or depressions in the femoral implant component.

Similarly, in certain embodiments, a tibial implant component can be designed and manufactured to include a post as a permanently integrated feature of the implant component. Alternatively, in some embodiments, the post can be modular. For example, the post can be designed and/or manufactured separate from the tibial implant component and optionally joined with the component, either prior to (e.g., preoperatively) or during the implant procedure. For example, a modular post and a tibial implant component can be mated using an integrating mechanism such as respective male and female screw threads, other male-type and female-type locking mechanisms, or other mechanisms capable of integrating the post into or onto the tibial implant component and providing stability to the post during normal wear. A modular post can be joined to a tibial implant component at the option of the surgeon or practitioner, for example, by removing a plug or other device that covers the integrating mechanism and attaching the modular post at the uncovered integrating mechanism. In some embodiments, a surgical kit may include a plurality of different posts configurations (standard and/or patient-adapted) from which the surgeon can select.

In some embodiments, the tibial implant component that the post is integral with, or configured to be joined to, may be a tibial tray. For example, the post may project from a joint facing surface of a tibial tray. Accordingly, one or more polyethylene inserts may be configured to wrap around the tibial post when inserted into the tibial tray. For example, in some embodiments in which medial and lateral polyethylene inserts are to be positioned on the tibial tray, the medial insert, the lateral insert, or both may include a cutout along a mesial edge to accommodate the tibial post.

In other embodiments, the tibial implant component that the post is integral with, or configured to be joined to, may be a polyethylene insert configured to be disposed on a tibial tray. In tibial implant embodiments comprising a medial and lateral polyethylene insert, the post may be configured to project from the medial insert, the lateral insert, or both. In some embodiments, it may be desirable to alter the size and shape of the medial and lateral polyethylene inserts relative to what their size and shape would be in a tibial implant not configured for posterior stabilization. For example, in some embodiments, the mesial edge of a medial insert 5140 may extend further laterally and may extend posteriorly at a lateral angel in order to accommodate tibial post 5150, as shown in FIG. 14, as compared to medial insert 5140B, as shown in FIG. 15, which is not configured to accommodate a tibial post. Additionally or alternatively, in some embodiments, the bearing surfaces of the one or more polyethylene inserts may be cross-linked, while the polyethylene comprising the post (modular or integral) may be non-cross-linked. Alternatively, in some embodiments, the polyethylene of the bearing surfaces and the inserts may be cross-linked.

In some embodiments, elements of an articular repair system may not be specifically designed with posterior stabilizing features for use in a PCL-sacrificing procedure but may be configured to accommodate the addition of posterior stabilizing features in the event that the PCL is sacrificed during the procedure. For example, the portion of the femoral component that will accommodate the box and/or cam can be standard, i.e., not-patient matched. In this manner, a stock of housings, receptacles or bars can be available in the operating room and added in case the surgeon sacrifices the PCL. In that case, the tibial insert can be exchanged for a tibial insert with a post mating with the box and/or cam for a posterior stabilized design.

In addition to the various posterior stabilizing features discussed above, and the features discussed in U.S. Patent Publication No. 2012-0209394, femoral and tibial implant component embodiments disclosed herein can include a number of other patient-adapted features and/or modifications. For example, in some embodiments, the femoral and/or tibial component can include one or more patient-adapted lugs. Such lugs can be configured, for example, to avoid interference with included posterior stabilizing features and/or to better accommodate forces relating to action on the posterior stabilizing features. Additionally or alternatively, a planned position, curvature, and/or slope of an articular surface of the femoral and/or tibial component may be adjusted to optimize one or more joint gap (e.g., flexion gap, extension gap) distances. For example, in some embodiments, an offset can be added to a posterior portion of one or more femoral condyles. The amount of such an offset may be based on patient-specific information, including, for example, a difference between subchondral bone and cartilage level at one or more locations and/or one or more tibial slopes. As another example, in some embodiments, the shape, dimensions, and/or curvature of one or more tibial and/or femoral articular surfaces may be adapted based on patient-specific information (e.g., the ligament information discussed above). In some such embodiment, the condylar surfaces may be adapted to guide and/or force a predetermined femoral rollback and/or rotation, optionally, with minimal or no influence of the post, box, and/or cams on the rollback and/or rotation.

Collecting and Modeling Patient-Specific Data

As mentioned above, certain embodiments include implant components designed and made using patient-specific data that is collected preoperatively. The patient-specific data can include points, surfaces, and/or landmarks, collectively referred to herein as “reference points.” In certain embodiments, the reference points can be selected and used to derive a varied or altered surface, such as, without limitation, an ideal surface or structure. For example, the reference points can be used to create a model of the patient's relevant biological feature(s) and/or one or more patient-adapted surgical steps, tools, and implant components. For example the reference points can be used to design a patient-adapted implant component having at least one patient-specific or patient-engineered feature, such as a surface, dimension, or other feature.

Reference points and/or data for obtaining measurements of a patient's joint, for example, relative-position measurements, length or distance measurements, curvature measurements, surface contour measurements, thickness measurements (in one location or across a surface), volume measurements (filled or empty volume), density measurements, and other measurements, can be obtained using any suitable technique. For example, one dimensional, two-dimensional, and/or three-dimensional measurements can be obtained using data collected from mechanical means, laser devices, electromagnetic or optical tracking systems, molds, materials applied to the articular surface that harden as a negative match of the surface contour, and/or one or more imaging techniques described above and/or known in the art. Data and measurements can be obtained non-invasively and/or preoperatively. Alternatively, measurements can be obtained intraoperatively, for example, using a probe or other surgical device during surgery.

In certain embodiments, imaging data collected from the patient, for example, imaging data from one or more of x-ray imaging, digital tomosynthesis, cone beam CT, non-spiral or spiral CT, non-isotropic or isotropic MRI, SPECT, PET, ultrasound, laser imaging, photo-acoustic imaging, is used to qualitatively and/or quantitatively measure one or more of a patient's biological features, one or more of normal cartilage, diseased cartilage, a cartilage defect, an area of denuded cartilage, subchondral bone, cortical bone, endosteal bone, bone marrow, a ligament, a ligament attachment or origin, menisci, labrum, a joint capsule, articular structures, and/or voids or spaces between or within any of these structures. The qualitatively and/or quantitatively measured biological features can include, but are not limited to, one or more of length, width, height, depth and/or thickness; curvature, for example, curvature in two dimensions (e.g., curvature in or projected onto a plane), curvature in three dimensions, and/or a radius or radii of curvature; shape, for example, two-dimensional shape or three-dimensional shape; area, for example, surface area and/or surface contour; perimeter shape; and/or volume of, for example, the patient's cartilage, bone (subchondral bone, cortical bone, endosteal bone, and/or other bone), ligament, and/or voids or spaces between them.

In certain embodiments, measurements of biological features can include any one or more of the illustrative measurements identified in Table 4.

TABLE 4
Exemplary patient-specific measurements of biological features
that can be used in the creation of a model and/or in the selection
and/or design of an implant component
Anatomical feature    Exemplary measurement
Joint-line, joint gap Location relative to proximal reference point
                      Location relative to distal reference point
                      Angle
                      Gap distance between opposing surfaces in one or
                      more locations
                      Location, angle, and/or distance relative to
                      contralateral joint
Soft tissue tension   Joint gap distance
and/or balance        Joint gap differential, e.g., medial to lateral
Medullary cavity      Shape in one or more dimensions
                      Shape in one or more locations
                      Diameter of cavity
                      Volume of cavity
Subchondral bone      Shape in one or more dimensions
                      Shape in one or more locations
                      Thickness in one or more dimensions
                      Thickness in one or more locations
                      Angle, e.g., resection cut angle
Cortical bone         Shape in one or more dimensions
                      Shape in one or more locations
                      Thickness in one or more dimensions
                      Thickness in one or more locations
                      Angle, e.g., resection cut angle
                      Portions or all of cortical bone perimeter at an
                      intended resection level
Endosteal bone        Shape in one or more dimensions
                      Shape in one or more locations
                      Thickness in one or more dimensions
                      Thickness in one or more locations
                      Angle, e.g., resection cut angle
Cartilage             Shape in one or more dimensions
                      Shape in one or more locations
                      Thickness in one or more dimensions
                      Thickness in one or more locations
                      Angle, e.g., resection cut angle
Intercondylar notch   Shape in one or more dimensions
                      Location
                      Height in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Angle, e.g., resection cut angle
Medial condyle        2D and/or 3D shape of a portion or all
                      Height in one or more locations
                      Length in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Thickness in one or more locations
                      Curvature in one or more locations
                      Slope in one or more locations and/or directions
                      Angle, e.g., resection cut angle
                      Portions or all of cortical bone perimeter at an
                      intended resection level
                      Resection surface at an intended resection level
Lateral condyle       2D and/or 3D shape of a portion or all
                      Height in one or more locations
                      Length in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Thickness in one or more locations
                      Curvature in one or more locations
                      Slope in one or more locations and/or directions
                      Angle, e.g., resection cut angle
                      Portions or all of cortical bone perimeter at an
                      intended resection level
                      Resection surface at an intended resection level
Trochlea              2D and/or 3D shape of a portion or all
                      Height in one or more locations
                      Length in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Thickness in one or more locations
                      Curvature in one or more locations
                      Groove location in one or more locations
                      Trochlear angle, e.g. groove angle in one or more
                      locations
                      Slope in one or more locations and/or directions
                      Angle, e.g., resection cut angle
                      Portions or all of cortical bone perimeter at an
                      intended resection level
                      Resection surface at an intended resection level
Medial trochlea       2D and/or 3D shape of a portion or all
                      Height in one or more locations
                      Length in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Thickness in one or more locations
                      Curvature in one or more locations
                      Slope in one or more locations and/or directions
                      Angle, e.g., resection cut angle
                      Portions or all of cortical bone perimeter at an
                      intended resection level
                      Resection surface at an intended resection level
Central trochlea      2D and/or 3D shape of a portion or all
                      Height in one or more locations
                      Length in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Thickness in one or more locations
                      Curvature in one or more locations
                      Groove location in one or more locations
                      Trochlear angle, e.g. groove angle in one or more
                      locations
                      Slope in one or more locations and/or directions
                      Angle, e.g., resection cut angle
                      Portions or all of cortical bone perimeter at an
                      intended resection level
                      Resection surface at an intended resection level
Lateral trochlea      2D and/or 3D shape of a portion or all
                      Height in one or more locations
                      Length in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Thickness in one or more locations
                      Curvature in one or more locations
                      Slope in one or more locations and/or directions
                      Angle, e.g., resection cut angle
                      Portions or all of cortical bone perimeter at an
                      intended resection level
                      Resection surface at an intended resection level
Entire tibia          2D and/or 3D shape of a portion or all
                      Height in one or more locations
                      Length in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Thickness in one or more locations
                      Curvature in one or more locations
                      Slope in one or more locations and/or directions
                      (e.g. medial and/or lateral)
                      Angle, e.g., resection cut angle
                      Axes, e.g., A-P and/or M-L axes
                      Osteophytes
                      Plateau slope(s), e.g., relative slopes medial and
                      lateral
                      Plateau heights(s), e.g., relative heights medial and
                      lateral
                      Bearing surface radii, e.g., e.g., relative radii medial
                      and lateral
                      Perimeter profile
                      Portions or all of cortical bone perimeter at an
                      intended resection level
                      Resection surface at an intended resection level
Medial tibia          2D and/or 3D shape of a portion or all
                      Height in one or more locations
                      Length in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Thickness or height in one or more locations
                      Curvature in one or more locations
                      Slope in one or more locations and/or directions
                      Angle, e.g., resection cut angle
                      Perimeter profile
                      Portions or all of cortical bone perimeter at an
                      intended resection level
                      Resection surface at an intended resection level
Lateral tibia         2D and/or 3D shape of a portion or all
                      Height in one or more locations
                      Length in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Thickness/height in one or more locations
                      Curvature in one or more locations
                      Slope in one or more locations and/or directions
                      Angle, e.g., resection cut angle
                      Perimeter profile
                      Portions or all of cortical bone perimeter at an
                      intended resection level
                      Resection surface at an intended resection level
Entire patella        2D and/or 3D shape of a portion or all
                      Height in one or more locations
                      Length in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Thickness in one or more locations
                      Curvature in one or more locations
                      Slope in one or more locations and/or directions
                      Perimeter profile
                      Angle, e.g., resection cut angle
                      Portions or all of cortical bone perimeter at an
                      intended resection level
                      Resection surface at an intended resection level
Medial patella        2D and/or 3D shape of a portion or all
                      Height in one or more locations
                      Length in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Thickness in one or more locations
                      Curvature in one or more locations
                      Slope in one or more locations and/or directions
                      Angle, e.g., resection cut angle
                      Portions or all of cortical bone perimeter at an
                      intended resection level
                      Resection surface at an intended resection level
Central patella       2D and/or 3D shape of a portion or all
                      Height in one or more locations
                      Length in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Thickness in one or more locations
                      Curvature in one or more locations
                      Slope in one or more locations and/or directions
                      Angle, e.g., resection cut angle
                      Portions or all of cortical bone perimeter at an
                      intended resection level
                      Resection surface at an intended resection level
Lateral patella       2D and/or 3D shape of a portion or all
                      Height in one or more locations
                      Length in one or more locations
                      Width in one or more locations
                      Depth in one or more locations
                      Thickness in one or more locations
                      Curvature in one or more locations
                      Slope in one or more locations and/or directions
                      Angle, e.g., resection cut angle
                      Portions or all of cortical bone perimeter at an
                      intended resection level
                      Resection surface at an intended resection level

A single or any combination or all of the measurements described in Table 4 and/or known in the art can be used. Additional patient-specific measurements and information that can be used in the evaluation can include, for example, joint kinematic measurements, bone density measurements, bone porosity measurements, identification of damaged or deformed tissues or structures, and patient information, such as patient age, weight, gender, ethnicity, activity level, and overall health status. Moreover, the patient-specific measurements may be compared, analyzed or otherwise modified based on one or more “normalized” patient model or models, or by reference to a desired database of anatomical features of interest. For example, a series of patient-specific femoral measurements may be compiled and compared to one or more exemplary femoral or tibial measurements from a library or other database of “normal” femur measurements. Comparisons and analysis thereof may concern, but is not limited to one, more or any combination of the following dimensions: femoral shape, length, width, height, of one or both condyles, intercondylar shapes and dimensions, trochlea shape and dimensions, coronal curvature, sagittal curvature, cortical/cancellous bone volume and/or quality, etc., and a series of recommendations and/or modifications may be accomplished.

Claims

1. A patient-adapted articular repair system for treatment of a knee joint of a patient, the knee joint including a femur and a tibia, the system comprising: a femoral implant component, the femoral implant component comprising: a medial condyle portion;a lateral condyle portion;a box portion substantially disposed between the medial condyle portion and the lateral condyle portion, the box portion including a medial box wall and a lateral box wall;a cam portion substantially disposed between the medial condyle portion and the lateral condyle portion; anda tibial implant component, the tibial implant component comprising: a medial articular-bearing surface portion;a lateral articular-bearing surface portion;a post portion, the post portion substantially disposed between the medial articular bearing surface portion and the lateral articular bearing surface portion and extending substantially superiorly from the tibial implant component,wherein a width of the box comprises the distance from at least a portion of the medial box wall to at least a portion of the lateral box wall,wherein at least a portion of the medial box wall and/or a portion of the lateral box wall has a box-wall thickness,wherein the box width is based, at least in part, on patient-specific information, andwherein the patient-specific information comprises one or more patient-specific dimensions selected from the group of patient-specific dimensions consisting of a mediolateral length of the femur, a mediolateral length of the tibia, and a distance from a medial-most point of a medial epicondyle of the femur to a lateral-most point of a lateral epicondyle of the femur.

2. A patient-adapted articular repair system for treatment of a knee joint of a patient, the knee joint including a femur and a tibia, the system comprising: a femoral implant component, the femoral implant component comprising: a medial condyle portion;a lateral condyle portion;a box portion substantially disposed between the medial condyle portion and the lateral condyle portion, the box portion including a medial box wall and a lateral box wall;a cam portion substantially disposed between the medial condyle portion and the lateral condyle portion; anda tibial implant component, the tibial implant component comprising: a medial articular-bearing surface portion;a lateral articular-bearing surface portion;a post portion, the post portion substantially disposed between the medial articular bearing surface portion and the lateral articular bearing surface portion and extending substantially superiorly from the tibial implant component,wherein a width of the box comprises the distance from at least a portion of the medial box wall to at least a portion of the lateral box wall,wherein at least a portion of the medial box wall and/or a portion of the lateral box wall has a box-wall thickness, andwherein the box width is based, at least in part, on patient-specific information.

3. A patient-adapted femoral implant component for treatment of a knee joint of a patient, the knee joint including a femur and a tibia, the femoral implant component comprising: a medial condyle portion;a lateral condyle portion;a box portion substantially disposed between the medial condyle portion and the lateral condyle portion, the box portion including a medial box wall and a lateral box wall; anda cam portion substantially disposed between the medial condyle portion and the lateral condyle portion,wherein a width of the box comprises the distance from at least a portion of the medial box wall to at least a portion of the lateral box wall,wherein at least a portion of the medial box wall and/or a portion of the lateral box wall has a box-wall thickness,wherein the box width is based, at least in part, on patient-specific information, andwherein the patient-specific information comprises one or more patient-specific dimensions selected from the group of patient-specific dimensions consisting of a mediolateral length of the femur, a mediolateral length of the tibia, and a distance from a medial-most point of a medial epicondyle of the femur to a lateral-most point of a lateral epicondyle of the femur.

4. A patient-adapted tibial implant component for treatment of a knee joint of a patient, the knee joint including a femur and a tibia, the tibial implant component comprising: a medial articular-bearing surface portion;a lateral articular-bearing surface portion; anda post portion, the post portion substantially disposed between the medial articular bearing surface portion and the lateral articular bearing surface portion and extending substantially superiorly from the tibial implant component,wherein at least a portion of the post portion comprises a substantially circular cross-section in a transverse plane, a radius of the substantially circular cross-section based, at least in part, on patient-specific information, andWherein the patient-specific information comprises one or more patient-specific dimensions selected from the group of patient-specific dimensions consisting of a mediolateral length of the femur, a mediolateral length of the tibia, and a distance from a medial-most point of a medial epicondyle of the femur to a lateral-most point of a lateral epicondyle of the femur.

5. The articular repair system of claim 1, wherein the box-wall thickness is based, at least in part, on the patient-specific information.

6. The articular repair system of claim 1, wherein a thickness of at least a portion of the cam portion is based, at least in part, on the patient-specific information.

7. The articular repair system of claim 1, wherein the cam portion includes a cam and at least one cam arm that connects the cam to a portion of the medial box wall and/or a portion of the lateral box wall, the cam and/or the cam arm having a thickness that is based, at least in part, on the patient-specific information.

8. The articular repair system of claim 1, wherein the cam portion includes a cam and at least one cam arm that connects the cam to a portion of the medial box wall and/or a portion of the lateral box wall, and wherein one or more radii of curvature of at least a portion of the cam and/or the cam arm is based, at least in part, on the patient-specific information.

9. The articular repair system of claim 1, wherein the cam portion includes at least one cam arm connecting the cam to the medial box wall and/or the lateral box wall, and wherein at least a portion of the cam arm has a thickness that is based, at least in part, on the patient-specific information.

10. The articular repair system of claim 1, wherein at least a portion of the post portion comprises a substantially circular cross-section in a transverse plane, a radius of the substantially circular cross-section based, at least in part, on the patient-specific information.

11. The articular repair system of claim 1, wherein a mediolateral center of the box portion is substantially aligned with a sagittal plane of the knee joint that is substantially mediolaterally centered with respect to the knee joint when the femoral component is disposed in a predetermined position on the femur of the knee joint.

12. The articular repair system of claim 1, wherein a mediolateral center of the post portion is substantially aligned with a sagittal plane of the knee joint that is substantially mediolaterally centered with respect to the knee joint when the tibial component is disposed in a predetermined position on the tibia of the knee joint.

13. The articular repair system of claim 1, wherein at least a portion of a shape of a joint-facing surface of the medial condyle portion is derived, at least in part, from patient-specific information, and at least a portion of a shape of a joint-facing surface of the lateral condyle portion is derived, at least in part, from patient-specific information.

14. The articular repair system of claim 1, wherein at least a portion of a shape of the medial articular-bearing surface is derived, at least in part, from patient-specific information, and at least a portion of a shape of the lateral articular-bearing surface is derived, at least in part, from patient-specific information.

15. (canceled)