Patent Application
20170296349
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.
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.
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 change posterior insert height or slope or curvature relative to the corresponding femoral radius on the posterior condyle.
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
In various embodiments, an intercondylar box 4910 may be included in a femoral implant component, as shown, for example, in
Additionally or alternatively, one or more intercondylar cams 5010, 5012 may be included in a femoral implant component, as shown, for example, in
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).
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”) 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
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; 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. Additionally or alternatively, additional 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. By way of example, in some embodiments, one or more dimensions of the post, box, and/or cam(s) can be designed and/or selected to avoid patellar surface impingement. 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). 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.
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
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
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
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., trochlear 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,
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 above and a posterior-stabilizing 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 curvature to a post, box, and/or cam curvature. 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 some embodiments, for example, a simulation can begin with modeling articular surfaces of femoral and/or tibial components, based, for example, on a cruciate-retaining design (e.g., as disclosed in U.S. Patent Publication No. 2012-0209394). Next, varying predictiles can be created by modeling the components in engagement at varying degrees of flexion/extension. Relative locations of features (e.g., length, width, height, orientation, slope and/or curvature) of portions of a proposed box, post, and/or cam(s) 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, or about 70 degrees of flexion). Additionally or alternatively, a desired maximum flexion angle may also be set (e.g., at 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, a cam (optionally, including a tongue), or portion thereof, may be selected and/or designed 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 that includes a post (standard or patient-adapted) 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
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 cam bearing surface 316a and centered on circle 314, as illustrated in
Optionally, in some embodiments, at one or more flexion angles in the above method, 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
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
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 measureable 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
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.
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.
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
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.
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.
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.
This application is a continuation of U.S. patent application Ser. No. 14/775,155, entitled “Posterior-Stabilized Knee Implant Components and Instruments,” filed Sep. 11, 2015, which in turn is a U.S. national state entry under 35 USC §371 of PCT/US14/27446, entitled “Posterior-Stabilized Knee Implant Components and Instruments,” filed Mar. 14, 2014, which in turn claims the benefit of U.S. Provisional Application No. 61/801,009, entitled “Posterior Stabilized Knee Implants, Designs And Related Methods And Tools,” filed Mar. 15, 2013. Each of the above-described applications is hereby incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61801009 | Mar 2013 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14775155 | Sep 2015 | US |
| Child | 15638863 | US |
