Patent Publication Number: US-2021161681-A1

Title: Universal femoral trial system and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation-in-part of U.S. patent application Ser. No. 15/622,688 filed on Jun. 14, 2017, entitled KNEE ARTHROPLASTY SYSTEMS AND METHODS, which claims the benefit of U.S. Provisional Application No. 62/466,249 filed on Mar. 2, 2017, entitled COMPOSITE JOINT ARTHROPLASTY SYSTEMS AND METHODS. The present application is also a continuation-in-part of U.S. patent application Ser. No. 16/046,554 filed on Jul. 26, 2018, entitled MODULAR KNEE PROTHESIS, which claims the benefit of U.S. Provisional Application No. 62/537,106 filed on Jul. 26, 2017, entitled MODULAR KNEE PROSTHESIS. The present application is also a continuation-in-part of U.S. patent application Ser. No. 16/505,595 filed on Jul. 8, 2019, entitled ORTHOPEDIC IMPLANTS AND METHODS, which claims the benefit of U.S. Provisional Application No. 62/694,834 filed on Jul. 6, 2018, entitled ORTHOPEDIC IMPLANTS AND METHODS. The present application is also a continuation-in-part of U.S. patent application Ser. No. 16/046,583 filed on Jul. 26, 2018, entitled UNIVERSAL FEMORAL TRIAL SYSTEM AND METHODS, which claims the benefit of U.S. Provisional Application No. 62/537,106 filed on Jul. 26, 2017, entitled MODULAR KNEE PROSTHESIS. The above-referenced applications are incorporated by reference as though set forth herein in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to surgical devices, systems, instruments, and methods. More specifically, the present disclosure relates to orthopedic knee replacement surgical devices, instruments, systems, and methods. 
     BACKGROUND 
     A number of knee replacement options exist which may be implemented depending upon the level of compromise of the natural knee anatomy. The knee anatomy complex includes the knee joint between the femur distal end and the tibia proximal end, and the surrounding anterior and posterior cruciate ligaments (ACL, PCL), and medial and lateral collateral ligaments (MCL, LCL), which provide support and stabilization to the knee joint. When one or more ligaments are compromised, for example through injury, disease, or aging, a knee prosthesis system may be implanted to replace the knee joint. 
     In a situation where the anterior cruciate ligament is compromised, it may be removed and a cruciate retaining (CR) knee prosthesis system, which allows retention of the posterior cruciate ligament and the collateral ligaments, may be implanted. Typical CR knee prosthesis femoral components and tibial inserts have large U-shaped openings providing room for the extant PCL, MCL, and LCL ligaments. 
     In a case where both the anterior and posterior cruciate ligaments are compromised but, yet the collateral ligaments are functional, both the ACL and PCL may be removed, and a posterior stabilizing (PS) knee prosthesis system may be implanted. A typical PS tibial insert includes a central post, and many PS femoral components include a cam element extending between the medial and lateral condyles. The post and cam interact to provide stability in place of the removed PCL ligament. 
     In a case where the anterior and posterior cruciate ligaments are compromised, and the collateral ligaments are unstable, both the ACL and PCL may be removed and a constrained condylar knee (CCK) prosthesis system may be implanted. In a case where all four ligaments are compromised, all ligaments may be removed, and a hinge type knee replacement system may be implanted. 
     A typical knee prosthesis system includes a tibial bone anchoring component, a tibial articulating component, which may be called a tibial insert, and a femoral bone anchoring component. Since the tibial and femoral bone anchoring components are anchored to bone through various fasteners, cement, and/o bone ingrowth, it may be difficult and invasive to remove and replace either of the bone anchoring components, should the need arise. The tibial insert is typically made of polyethylene, and since it is not anchored to bone, is much more easily replaced if necessary. For example, a patient may have a CR knee prosthesis and then experience compromise of the PCL, thus requiring replacement of the CR knee prosthesis with a PS knee prosthesis. Or, a patient may have a PS knee prosthesis and then experience instability of the collateral ligaments, thus requiring replacement of the PS knee prosthesis with a CCK prosthesis. 
     SUMMARY 
     The various systems and methods of the present disclosure have been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available technology. 
     In an embodiment, an assembly for facilitating orthopedic surgery may include a body with a drill guide connected to the body and an attachment mechanism connected to the body. The attachment mechanism may include a first tab, a second tab, and a handle connected to the first and second tabs. The rotation of the handle about an axis may cause the first and second tabs to extend outward from the body to secure the body to an external frame secured to a patient. The drill guide may further include at least one drill guide aperture that extends through the drill guide and through the body. The drill guide may further include at least one broach guide aperture that extends through the drill guide and through the body. The at least one drill guide aperture may be in communication with the at least one broach guide aperture. 
     The first tab and the second tab each may have a proximal end and a distal end, and the proximal ends of the tabs may be adjacent to one another and the distal ends of the tabs may extend away from each other. The proximal ends of the tabs may each have a handle attachment feature and the handle may further include tab attachment features complementary to the handle attachment features on each of the tabs. The rotation of the handle about the axis may cause each of the first tab and the second tab to transition between a retracted position and an extended position, relative to the body. The proximal ends of the first and second tabs may be located within a cavity in the body so that the handle attachment features and/or the tab attachment features extend into the cavity. At least one of the first tab and the second tab may further include a stop member and the body may further include an abutment member. The rotation of the handle may cause the stop member to engage the abutment member to retain the at least one of the first tab and the second tab in the extended position. 
     The first and the second tabs each may have a proximal end, a distal end, and an intermediate section therebetween. The intermediate section may be compressible such that the proximal end and the distal end are configured to be translatable. The assembly may further include the external frame which may be a trial component for joint arthroplasty. The first and second tabs each may have a proximal end, a distal end, and an intermediate section therebetween. The trial component may have a receiving aperture shaped to receive the body and locking apertures, in communication with the receiving aperture, shaped to receive the distal ends of the first tab and the second tab when the handle is rotated with the body positioned in the receiving aperture. 
     In an embodiment, an assembly may include a body, and a drill and broach guide. The drill and broach guide may include a first drill guide aperture, a second drill guide aperture, a third drill guide aperture, a first broach guide aperture intermediate the first drill guide aperture and the second drill guide aperture, and a second broach guide aperture intermediate the second drill guide aperture and the third drill guide aperture. The second drill guide aperture may be intermediate the first broach guide aperture and the second broach guide aperture. The assembly may have a locking mechanism including a handle connected to the body such that the handle is rotatable about an axis, a first tab having a first proximal end, a first distal end, and a first compressible intermediate section. The first proximal end may have a first handle connection feature, a second tab having a second proximal end, a second distal end, and a second compressible intermediate section. The second proximal end may have a second handle connection feature. The handle may be movably connected to the first handle connection feature and the second handle connection feature such that rotation of the handle about the axis extends the first and second tabs outward from the body. 
     The first and second tabs may be located within a cavity in the body. At least one of the first tab and the second tab may further have a stop member. The body may further have an abutment member. Rotation of the handle may cause the stop member to engage the abutment member to retain the at least one of the first tab and the second tab in the extended position. The handle may further have a circular base and a grip portion. The circular base may have a concave surface. The body may further have an aperture, surrounding the axis, extending from a first surface of the body to a second surface of the body. The circular base may engage the aperture. The handle may be rotatably secured to the base at the aperture by two pins extending into the base proximate an edge of the aperture, so that the pins securely engage the concave surface, allowing the handle to rotate about the axis. 
     The assembly may further include an external frame, which may be a trial component for joint arthroplasty. The trial component may further have a receiving aperture shaped to receive the body and locking apertures, in communication with the receiving aperture, shaped to receive the first and second distal ends of the first tab and the second tab when the handle is rotated with the body positioned in the receiving aperture. 
     In an embodiment, an assembly for preparing and trialing a bone to receive an implant, may include a body, a drill guide connected to the body, and an attachment mechanism connected to the body. The attachment mechanism may further include a first tab, a second tab, and a handle connected to the first and second tabs. The assembly may be configured to be removably coupled to a trial component by rotating the handle such that the first tab and the second tab are first in the retracted position, positioning the assembly adjacent to the trial component, and rotating the handle such that the first tab and the second tab move to the extended position and engage within corresponding attachment apertures in the trial component. At least one of the first tab and the second tab may further include a stop member and the body may further have an abutment member. The rotation of the handle may cause the stop member to engage the abutment member to retain the at least one of the first tab and second tab in in the extended position or a retracted position. 
     The first and the second tabs each may have a proximal end, a distal end, and an intermediate section therebetween. The handle may engage the first tab and the second tab at the proximal ends. The intermediate section may be compressible, and the handle may be rotatable to transition the first and second tabs to the extended position so that the distal ends of the first and second tabs enter the corresponding attachment apertures in the trial component. The intermediate section may be compressible such that, in response to the distal ends abutting a surface, the intermediate section is compressed to urge the stop member against the abutment member and prevents rotation of the handle. The distal ends may be configured to abut a surface and cause a compression of the intermediate section. The compression may urge the stop member against the abutment member and prevent rotation of the handle. The assembly may further include the external frame. The external frame may be a trial component for joint arthroplasty and may further include a receiving aperture shaped to receive the body. The first and second tabs may each have a proximal end, a distal end, and an intermediate section therebetween. The frame may further have locking apertures, in communication with the receiving aperture, shaped to receive the distal ends of the first tab and the second tab when the handle is rotated with the body positioned in the receiving aperture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages, nature, and additional features of exemplary embodiments of the disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only exemplary embodiments and are, therefore, not to be considered limiting of the disclosure&#39;s scope, the exemplary embodiments of the disclosure will be described with additional specificity and detail through use of the accompanying drawings in which: 
         FIG. 1A  is a perspective rear view of an assembly of the disclosure, including a posterior stabilizing femoral component and a tibial insert coupled in extension;  FIG. 1B  is a perspective front view of the assembly of  FIG. 1A  in flexion; 
         FIG. 2  is an exploded view of the assembly of  FIG. 1A ; 
         FIG. 3A  is a posterior view of the tibial insert of  FIG. 1A ;  FIG. 3B  is an anterior view of the tibial insert of  FIG. 1A ;  FIG. 3C  is a superior view of the tibial insert of  FIG. 1A ;  FIG. 3D  is a medial side view of the tibial insert of  FIG. 1A ; 
         FIG. 4  is a top down view of the assembly of  FIG. 1A ; 
         FIG. 5  is a top down cross-sectional view of the assembly of  FIG. 1A , taken along line B-B in  FIG. 6 ; 
         FIG. 6  is a posterior cross-sectional view of the assembly of  FIG. 1A , taken along line A-A in  FIG. 5 ; 
         FIG. 7  is a top down cross-sectional view of the assembly of  FIG. 1B , taken along line C-C in  FIG. 8 ; 
         FIG. 8  is a posterior cross-sectional view of the assembly of  FIG. 1B , taken along line D-D in  FIG. 7 ; 
         FIG. 9  is a perspective rear view of an assembly of the disclosure, including a cruciate retaining femoral component and the tibial insert of  FIG. 1A  coupled in extension; 
         FIG. 10  is an exploded perspective rear view of the assembly of  FIG. 9 ; 
         FIG. 11A  is a perspective rear view of another tibial insert of the disclosure;  FIG. 11B  is a top view of the tibial insert of  FIG. 11A ;  FIG. 11C  is a posterior view of the tibial insert of  FIG. 11A ;  FIG. 11D  is an anterior view of the tibial insert of  FIG. 11A ;  FIG. 11E  is a bottom view of the tibial insert of  FIG. 11A ; 
         FIG. 12A  is a perspective rear view of another tibial insert of the disclosure;  FIG. 12B  is a top view of the tibial insert of  FIG. 12A ;  FIG. 12C  is a bottom view of the tibial insert of  FIG. 12A ;  FIG. 12D  is a posterior view of the tibial insert of  FIG. 12A ;  FIG. 12E  is an anterior view of the tibial insert of  FIG. 12A ;  FIG. 12F  is a medial side view of the tibial insert of  FIG. 12A ; 
         FIG. 13  is a chart demonstrating the interchangeability of the tibial inserts disclosed herein with various femoral components; 
         FIG. 14  is an exploded rear view of another assembly of the disclosure, including a posterior stabilizing femoral component and a posterior stabilizing tibial insert; 
         FIG. 15  is another exploded rear view of the assembly of  FIG. 14 ; 
         FIG. 16A  is a posterior view of the tibial insert of  FIG. 14 ;  FIG. 16B  is an anterior view of the tibial insert of  FIG. 14 ;  FIG. 16C  is a superior view of the tibial insert of  FIG. 14 ;  FIG. 16D  is a medial side view of the tibial insert of  FIG. 14 ; 
         FIG. 17  is an exploded rear view of another assembly of the disclosure, including a cruciate retaining femoral component with a keel and the posterior stabilizing tibial insert of  FIG. 14 ; 
         FIG. 18  is another exploded rear view of the assembly of  FIG. 17 ; 
         FIG. 19  is an exploded rear view of another assembly of the disclosure, including a cruciate retaining femoral component without a keel and the posterior stabilizing tibial insert of  FIG. 14 ; 
         FIG. 20  is another exploded rear view of the assembly of  FIG. 19 ; 
         FIG. 21A  is a perspective rear view of another tibial insert of the disclosure;  FIG. 21B  is a top view of the tibial insert of  FIG. 21A ;  FIG. 21C  is a posterior view of the tibial insert of FIG.  21 A;  FIG. 21D  is an anterior view of the tibial insert of  FIG. 21A ;  FIG. 21E  is a bottom view of the tibial insert of  FIG. 21A ; 
         FIG. 22A  is a perspective rear view of another tibial insert of the disclosure;  FIG. 22B  is a top view of the tibial insert of  FIG. 22A ;  FIG. 22C  is a bottom view of the tibial insert of  FIG. 22A ;  FIG. 22D  is a posterior view of the tibial insert of  FIG. 22A ;  FIG. 22E  is an anterior view of the tibial insert of  FIG. 22A ;  FIG. 22F  is a medial side view of the tibial insert of  FIG. 22A ; 
         FIG. 23A  is a perspective front view of the femoral component of  FIG. 14  coupled to one or more augments of the present disclosure;  FIG. 23B  is a medial side view of the femoral component of  FIG. 23A ; 
         FIG. 24A  is a perspective top view of a femoral trial component of the disclosure;  FIG. 24B  is a perspective rear view of the femoral trial component of  FIG. 24A ;  FIG. 24C  is a lateral side view of the femoral trial component of  FIG. 24A ;  FIG. 24D  is a medial side view of the femoral trial component of  FIG. 24A ;  FIG. 24E  is an anterior view of the femoral trial component of  FIG. 24A ;  FIG. 24F  is a posterior view of the femoral trial component of  FIG. 24A ;  FIG. 24G  is a superior view of the femoral trial component of  FIG. 24A ;  FIG. 24H  is an inferior view of the femoral trial component of  FIG. 24A ; 
         FIG. 25A  is a perspective rear view of a posterior stabilizing notch cutting guide assembly of the disclosure;  FIG. 25B  is another perspective rear view of the posterior stabilizing notch cutting guide assembly of  FIG. 25A ;  FIG. 25C  is a medial side view of the posterior stabilizing notch cutting guide assembly of  FIG. 25A ;  FIG. 25D  is a top view of the posterior stabilizing notch cutting guide assembly of  FIG. 25A ; 
         FIG. 26  is a partial exploded view of the posterior stabilizing notch cutting guide assembly of  FIG. 25A ; 
         FIG. 27A  is a posterior view of the posterior stabilizing notch cutting guide assembly of  FIG. 25A  above the femoral trial component of  FIG. 24A ;  FIG. 27B  is posterior view of the posterior stabilizing notch cutting guide assembly of  FIG. 27A  coupled to the femoral trial component of  FIG. 27A ; 
         FIG. 28A  is a perspective rear view of a posterior stabilizing trial attachment of the disclosure;  FIG. 28B  is another perspective rear view of the posterior stabilizing trial attachment of  FIG. 28A ;  FIG. 28C  is a perspective front view of the posterior stabilizing trial attachment of  FIG. 28A ;  FIG. 28D  is a perspective side view of the posterior stabilizing trial attachment of  FIG. 28A ; 
         FIG. 29A  is a posterior view of the posterior stabilizing trial attachment of  FIG. 28A  above the femoral trial component of  FIG. 24A ;  FIG. 29B  is a posterior view of the posterior stabilizing trial attachment of  FIG. 29A  coupled to the femoral trial component of  FIG. 29A ; 
         FIG. 30A  is a perspective rear view of a drill and broach guide assembly of the disclosure;  FIG. 30B  is a perspective bottom view of the drill and broach guide assembly of  FIG. 30A ;  FIG. 30C  is a top view of the drill and broach guide assembly of  FIG. 30A ;  FIG. 30D  is a bottom view of the drill and broach guide assembly of  FIG. 30A ; 
         FIG. 31  is a partial exploded view of the drill and broach guide assembly of  FIG. 30A ; 
         FIG. 32A  is a posterior view of the drill and broach guide assembly of  FIG. 30A  above the femoral trial component of  FIG. 24A ;  FIG. 32B  is a posterior view of the drill and broach guide assembly of  FIG. 32A  coupled to the femoral trial component of  FIG. 32A ; 
         FIG. 33A  is a perspective front view of a cruciate retaining trial attachment of the disclosure;  FIG. 33B  is a perspective rear view of the cruciate retaining trial attachment of  FIG. 33A ;  FIG. 33C  is a perspective bottom view of the cruciate retaining trial attachment of  FIG. 33A ;  FIG. 33D  is a top view of the cruciate retaining trial attachment of  FIG. 33A ; 
         FIG. 34A  is a posterior view of the cruciate retaining trial attachment of  FIG. 33A  above the femoral trial component of  FIG. 24A ;  FIG. 34B  is a posterior view of the cruciate retaining trial attachment of  FIG. 34A  coupled to the femoral trial component of  FIG. 34A ; 
         FIG. 35A  is a perspective rear view of another femoral trial component of the disclosure;  FIG. 35B  is a posterior view of the femoral trial component of  FIG. 35A ;  FIG. 35C  is an anterior view of the femoral trial component of  FIG. 35A ; 
         FIG. 36  is a flow chart diagram of a method for preparing and trialing a femoral bone with a femoral trial component; 
         FIG. 37  is a flow chart diagram of a method for revising a knee joint prosthesis to provide increased stability; 
         FIG. 38A  is a perspective front view of a tibial tray of the disclosure;  FIG. 38B  is a perspective rear view of the tibial tray of  FIG. 38A ;  FIG. 38C  is an anterior view of the tibial tray of  FIG. 38A ;  FIG. 38D  is a posterior view of the tibial tray of  FIG. 38A ;  FIG. 38E  is a bottom view of the tibial tray of  FIG. 38A ;  FIG. 38F  is a top view of the tibial tray of  FIG. 38A ; and 
         FIG. 39  is an exploded view of a tibial tray mounting system of the disclosure that utilizes the tibial tray of  FIG. 38A . 
         FIG. 40  is a perspective rear view of an embodiment of a drill and broach guide assembly of the disclosure. 
         FIG. 41  is a side perspective view of the drill and broach guide assembly of  FIG. 40 . 
         FIG. 42  is a bottom view of the drill and broach guide assembly of  FIG. 40 . 
         FIG. 43  is a partial exploded view of the drill and broach guide assembly of  FIG. 40 . 
         FIG. 44  is a partial exploded bottom perspective view of the drill and broach guide assembly of  FIG. 40 . 
     
    
    
     It is to be understood that the drawings are for purposes of illustrating the concepts of the disclosure and may not be to scale. Furthermore, the drawings illustrate exemplary embodiments and do not represent limitations to the scope of the disclosure. 
     DETAILED DESCRIPTION 
     Exemplary embodiments of the disclosure will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. It will be readily understood that the components of the disclosure, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the apparatus, instruments, systems, and methods, as represented in the Figures, is not intended to limit the scope of the disclosure, as claimed, but is merely representative of exemplary embodiments of the disclosure. 
     Disclosed herein are components for a modular knee prosthesis system. This system may allow for revision procedures by replacement of only the tibial insert, allowing the originally implanted femoral and tibial anchoring components to remain implanted. The system may include CR tibial inserts, PS tibial inserts, and/or CCK tibial inserts. Any one of these tibial inserts may be interchangeably used with CR and/or PS femoral components disclosed herein to provide the stabilization needed to substitute for compromised or removed ligaments. The system may be used with any suitable tibial baseplate component, or tibial tray, to support the tibial insert. The PS tibial inserts disclosed herein may include tapered posts that permit the inserts to be used with cruciate retaining (CR) femoral components and/or posterior stabilizing (PS) femoral components. 
     Referring to  FIGS. 1A-2 , an assembly  10  for an implantable knee prosthesis is shown including a femoral component  14  and a tibial insert  12 . The femoral component  14  and tibial insert  12  are shown coupled in extension in  FIG. 1A , coupled in flexion in  FIG. 1B , and shown in an exploded view in  FIG. 2 . The tibial insert  12  may be further coupled to a tibial baseplate component (not shown) which may be implanted in a prepared tibia of a patient (also not shown). The femoral component  14  and tibial insert  12  illustrated in  FIGS. 1A-2  are right femoral and tibial insert components. Left femoral and tibial insert components (not shown) would be mirror images of the right femoral and tibial insert components shown in  FIGS. 1A-2 . The femoral component  14  may also be referred to as a posterior stabilizing femoral component  14  (or “PS femoral component”) and the tibial insert  12  may also be referred to as a posterior stabilizing tibial insert (or “PS insert”). 
       FIGS. 3A-3D  show the PS insert  12  of  FIGS. 1A-2  in isolation. The PS insert  12  may include a fixation side  20 , which may be an inferior side, opposite an articulation side  22 , which may be a superior side. The articulation side  22  may include a medial articulation portion  24  having a medial condylar articulation surface  25  and a lateral articulation portion  26  having a lateral condylar articulation surface  27 . A central portion  28  may separate the medial articulation portion  24  from the lateral articulation portion  26 . A post  30  may protrude superiorly from the central portion  28  and extend from a post base  38  to a post top or post superior end  40 . From the anterior perspective (shown in  FIG. 3B ) and/or the posterior perspective (shown in  FIG. 3A ), the post  30  may have its maximum medial-lateral or horizontal width toward the post superior end  40  of the post  30 , and its minimum medial-lateral or horizontal width toward the post base  38  of the post  30 . The post  30  may also be bilaterally symmetrical from the anterior and/or posterior perspectives. A recess  45  may be formed posterior to the central portion  28 , between the medial and lateral articulation portions  24 ,  26 , and may provide room for a posterior cruciate ligament (not shown). The PS insert  12  may further include an insert base  46 , which may further include an engagement feature  48  for engagement with a tibial baseplate component. 
     Continuing with  FIGS. 1A-3D , the post  30  may have an articulation surface  31  extending around the post  30  on the medial, posterior, lateral, and anterior aspects of the post  30 . The articulation surface  31  may include a medial articulation surface  32 , a lateral articulation surface  34 , an anterior post surface  36 , and a posterior articulation surface  42 . The medial and lateral articulation surfaces  32 ,  34  may be non-parallel to one another and taper inward from the post superior end  40  to the post base  38  relative to an insert midline vertical axis  2 , as shown in  FIGS. 3A and 3B . As shown in  FIG. 3A , an angle θ between the vertical axis  2  and each tapered surface  32 ,  34  may be about 6.5°, in at least one embodiment. Since the post  30  may be bilaterally symmetrical, the angle θ may be the same on both the medial and lateral articulation surfaces  32 ,  34  of the post  30 . In other embodiments of the disclosure, angle θ may range from about 6° to 11° degrees. The medial articulation surface  32  may be continuous with the medial condylar articulation surface  25 , and the lateral articulation surface  34  may be continuous with the lateral condylar articulation surface  27 , as can been further seen in cross-section in  FIGS. 6 and 8 . The anterior post surface  36  may extend between the medial and lateral articulation surfaces  32 ,  34  and may be convexly rounded. The anterior post surface  36  may also taper outward from the post superior end  40  to the post base  38  relative to the midline vertical axis  2 , as best seen in  FIG. 3D . In other embodiments of the PS insert  12 , the anterior post surface  36  may include less or no taper. 
     Referring to  FIG. 3C , the boundary of the post superior end  40  defines a rounded rim  44  shaped as a portion of a circle defined by a circular envelope  47 , as seen from a superior perspective. The post superior end  40  and rim  44  may be crescent-shaped with a concave recess toward a posterior end of the post  30  as shown, and may permit passage of the posterior cruciate ligament. The post superior end  40  may be circular; the rim  44  may provide increased rotational range of motion and surface contact against the femoral component  14  in comparison to traditional posts with a more square or rectangular shape and no rim. Thus, the rounded post superior end  40  and rim  44  may allow for surface contact with the femoral component  14  in contrast to the mere point or edge contact that is achieved by traditional posts that do not have these features. 
     The PS femoral component  14  depicted in  FIGS. 1-8  may include a cam element or cam bar  50  and a box structure  52  for providing posterior stabilization in place of absent ligaments. The cam bar  50  may include a cam articulating surface  51  which may contact the posterior articulation surface  42  of the post  30  during flexion, as in  FIGS. 1B and 7 . An internal articulation surface  54  may reside on the inside of the box structure  52  and may contact the post  30  during articulation and rotation of the knee joint. The internal articulating surface  54  may be concavely curved, and may contact the rim  44  of the post  30  during axial rotation of the knee joint about the post. The PS femoral component  14  may further include a medial condyle  60  having a medial condylar articulation surface  62 , and a lateral condyle  64  having a lateral condylar articulation surface  66 . The medial and lateral condylar articulation surfaces  62 ,  66  may articulate against the PS insert  12  medial and lateral condylar articulation surfaces  25 ,  27  respectively. A gap  68  may be formed between the medial and lateral condyles  60 ,  64 , with the cam bar  50  extending medial-laterally across the gap  68 . The internal articulation surface  54  may include a medial portion  70  continuous with a lateral portion  72 . In the embodiment depicted, a fixation post  74  may protrude superiorly from the PS femoral component  14 . However, in other embodiments of the PS femoral component  14 , the fixation post  74  may be absent and/or other fixation features such as posts, spikes, pegs, webs, keels or teeth may be present to affix the PS femoral component  14  to a prepared femur (not shown). 
     Referring to  FIGS. 9 and 10 , another assembly  110  embodiment of the disclosure may include the PS insert  12  of  FIGS. 1-8  coupled with a cruciate retaining femoral component  114  (or “CR femoral component”). The CR femoral component  114  may include medial and lateral condyles  160 ,  164 , with a gap  168  formed between the medial and lateral condyles  160 ,  164 . As a CR femoral component  114 , no cam bar or box may be present. The medial and lateral condyles  160 ,  164  may include medial and lateral condylar articulation surfaces  162 ,  166 , and an internal articulation surface  154  with medial and lateral articulating surfaces  170 ,  172 . 
     The medial and lateral articulation surfaces  32 ,  34  of the post  30  may be tapered and may permit natural articulation of the CR femoral component  114  with the PS insert  12 , which may not be achievable if the post  30  were not tapered. For example, if the post  30  had straight sides instead of tapered sides, the wider width of the post  30  at the base of the post  30  would interfere with the internal articulating surfaces  170 ,  172  of the medial and lateral condyles  160 ,  164 . When the PS femoral component  14  is coupled with the PS insert  12  to form assembly  10 , as in  FIG. 1A  and  FIG. 4 , the circular shape of the post superior end  40  in combination with the tapered medial and lateral articulation surfaces  32 ,  34  of the post  30 , may permit the PS femoral component  14  to articulate relative to the PS insert  12  in the manner of a posterior stabilized femoral component. However, when the PS insert  12  is paired and implanted with the CR femoral component  114 , the resultant assembly  110  may provide the native articulation and rotation of a cruciate retaining implant. 
     Referring to  FIGS. 11A-11E , an alternative embodiment of a tibial insert  212  is shown. Tibial insert  212  may be referred to as a cruciate retaining tibial insert  212  (or “CR insert”). In a system of the disclosure, CR insert  212  may be implanted with the CR femoral component  114  and a tibial baseplate component (not shown) to form a cruciate retaining knee prosthesis system. The CR insert  212  may include a fixation side  220 , which may be an inferior side, opposite an articulation side  222 , which may be a superior side. The articulation side  222  may include a medial articulation portion  224  having a medial condylar articulation surface  225  and a lateral articulation portion  226  having a lateral condylar articulation surface  227 . A central portion  228  may separate the medial articulation portion  224  from the lateral articulation portion  226 . A recess  245  may be formed posterior to the central portion  228 , between the medial and lateral articulation portions  224 ,  226 , and may provide room for a posterior cruciate ligament. The CR insert  212  may further include an insert base  246  and an engagement feature  248  for engagement with a tibial baseplate component. The CR insert  212  may be coupled with the CR femoral component  114  to form a cruciate retaining assembly. This assembly may be implanted with a suitable tibial baseplate as a cruciate retaining knee prosthesis. The CR insert  212  may also be coupled with the PS femoral component  14  and implanted with a suitable tibial baseplate. 
     Referring to  FIGS. 12A-12F , another alternative embodiment of a tibial insert  312  is shown. The tibial insert  312  may be referred to as a constrained condylar knee (CCK) tibial insert  312  (or “CCK insert”). The CCK insert  312  may include a fixation side  320 , which may be an inferior side, opposite an articulation side  322 , which may be a superior side. The articulation side  322  may include a medial articulation portion  324  having a medial condylar articulation surface  325  and a lateral articulation portion  326  having a lateral condylar articulation surface  327 . A central portion  328  may separate the medial articulation portion  324  from the lateral articulation portion  326 . A post  330  may protrude superiorly from the central portion  328 , and extend from a post base  338  to a top, or post superior end  340 . From the anterior perspective, as shown in  FIG. 12E , and the posterior perspective, as shown in  FIG. 12D , the post  330  may have its maximum medial-lateral or horizontal width at the superior end  340  of the post  330 , and its minimum medial-lateral or horizontal width at the post base  338  of the post  330 . The post  330  may be bilaterally symmetrical from the anterior and posterior perspectives. The CCK insert  312  may further include an insert base  346  and an engagement feature  348  for engagement with a tibial tray (not shown). 
     The post  330  may have an articulation surface  331  extending around the post  330  on the medial, posterior, lateral, and anterior aspects of the post  330 . The articulation surface  331  may include a medial articulation surface  332 , a lateral articulation surface  334 , an anterior post surface  336 , and a posterior articulation surface  342 . The medial and lateral articulation surfaces  332 ,  334  may taper slightly inward from the post superior end  340  to the post base  338  of the post  330  relative to an insert midline vertical axis  2 . However, some embodiments of CCK insert  312  may include no taper of the medial and lateral articulation surfaces  332 ,  334 . The medial articulation surface  332  may be continuous with the medial condylar articulation surface  325 , and the lateral articulation surface  334  may be continuous with the lateral condylar articulation surface  327 . The anterior post surface  336  may extend between the medial and lateral surfaces  332 ,  334  and may be convexly rounded. The anterior post surface  336  may taper outward from the post superior end  340  to the post base  338  relative to the midline axis  2 , as best seen in  FIG. 12F . In other embodiments of the CCK insert  312 , the anterior post surface  336  may include less taper, more taper, and/or no taper. The post  330  of the CCK insert  312  may be wider and bigger in diameter than the post  30  of PS insert  12 , for example to provide increased stability in the case of removal of the collateral ligaments. 
     Referring to  FIG. 12B , the boundary of the post superior end  340  may define a rounded rim  344  shaped as a portion of a circle, from a superior perspective. The post superior end  340  and rim  344  may be semi-circular as shown, however the rim  344  may define a circular envelope  347 . The post superior end  340  may be circular and rim  344  may provide increased surface contact and rotational range of motion when coupled and implanted with the PS femoral component  14  in comparison to traditionally shaped posts with a more square or rectangular shaped post. Thus, the rounded post superior end  340  and rim  344  may allow for surface contact with the femoral component  14  in contrast to the mere point or edge contact that is achieved by traditional posts that do not have these features. The CCK insert  312  may be coupled with the PS femoral component  14  to form a constrained condylar knee assembly, and this assembly may be implanted with a suitable tibial baseplate as a constrained condylar knee prosthesis. The CCK insert  312  may also be coupled with the CR femoral component  114  and implanted with a suitable tibial baseplate. Thus, all of the tibial inserts  12 ,  212 , and  312  disclosed herein are interchangeable with both the CR femoral component  114  and the PS femoral component  14 .  FIG. 13  is a chart showing the potential combinations of components. 
     The tibial inserts  12 ,  212 ,  312 , PS femoral component  14  and CR femoral component  114  may be grouped together as a modular knee replacement system and provided as a kit in one or more packages, in one non-limiting example. Another kit may include a CR femoral component  114 , a PS insert  12  and a CR insert  212 , in one or more packages in another non-limiting example. Yet another kit may include a PS femoral component  14 , a PS insert  12 , a CR insert  212 , and a CCK insert  312 , in one or more packages in yet another non-limiting example. However, it will also be understood that other kit embodiments may utilize any of the tibial inserts and/or femoral components described herein in any number or combination, in one or more packages. Furthermore, other components may also be including in any kit described herein, such as suitable tibial baseplate components, patellar components, etc., in one or more packages. It will also be understood that any of the tibial inserts disclosed herein may be formed of vitamin E polyethylene, highly cross linked polyethylene, ultra-high molecular weight polyethylene (UHMWPE), or any other suitable material. 
     In a method of the disclosure, a patient may initially experience compromise of the anterior cruciate ligament. The ACL may be removed, and a CR type prosthesis may be implanted, including a CR femoral component  114 , a CR insert  212 , and a tibial baseplate component. Later, the same patient may experience compromise of the PCL and may need additional stabilization of the knee joint. The PCL may be removed, the CR tibial insert  212  may be removed, and a PS tibial insert  12  of the disclosure may be inserted between the originally implanted CR femoral component  114  and the tibial baseplate component, thus providing additional stability for the missing PCL. Even later, the same patient may experience instability of the collateral ligaments. The PS tibial insert  12  may be removed, and the CCK tibial insert  312  of the disclosure may be inserted between the originally implanted CR femoral component  114  and the tibial baseplate component. Thus, the patient may progress from a CR knee prosthesis, to a PS knee prosthesis, and finally to a CCK knee prosthesis without requiring replacement of the originally implanted femoral and/or tibial baseplate components. The interchangeability of the inserts  12 ,  212 ,  312  permit replacement of only the tibial insert component in order to provide increasing levels of support and stability to the knee joint. 
     In another method of the disclosure, a patient may initially experience compromise of both the ACL and the PCL. These ligaments may be removed, and a PS type prosthesis may be implanted, including a PS femoral component  14 , a PS insert  12 , and a tibial baseplate component. Later, the same patient may experience instability of the collateral ligaments. The PS insert  12  may be removed, and a CCK insert  312  may be inserted between the originally implanted PS femoral component  14  and the tibial baseplate component. Thus, the patient may progress from a PS knee prosthesis to a CCK knee prosthesis without requiring replacement of the originally implanted PS femoral component  14  and tibial baseplate component. 
     Referring to  FIGS. 14 and 15 , another assembly  1010  of the disclosure for an implantable knee prosthesis is shown in various exploded rear views. The assembly  1010  may include a femoral component  1014  and a tibial insert  1012 . The tibial insert  1012  may be further coupled to a tibial baseplate component (not shown) which may also be implanted in a prepared tibia of a patient (not shown). The femoral component  1014  and tibial insert  1012  illustrated in  FIGS. 14 and 15  are right side femoral and tibial insert components. Left side femoral and tibial insert components (not shown) would be mirror images of the right side femoral and tibial insert components that are shown in  FIGS. 14 and 15 . The femoral component  1014  may also be referred to as a posterior stabilizing femoral component  1014  (or “PS femoral component”) and the tibial insert  1012  may also be referred to as a posterior stabilizing tibial insert (or “PS insert”). 
       FIGS. 16A-16D  show the PS insert  1012  of  FIGS. 15 and 14  in isolation. The PS insert  1012  may include a fixation side  1020 , which may be an inferior side, opposite an articulation side  1022 , which may be a superior side. The articulation side  1022  may include a medial articulation portion  1024  having a medial condylar articulation surface  1025  and a lateral articulation portion  1026  having a lateral condylar articulation surface  1027 . A central portion  1028  may separate the medial articulation portion  1024  from the lateral articulation portion  1026 . A post  1030  may protrude superiorly from the central portion  1028  and extend from a post base  1038  to a post top  1040  or post superior end. From the anterior perspective (shown in  FIG. 16B ) and/or the posterior perspective (shown in  FIG. 16A ), the post  1030  may have its maximum medial-lateral or horizontal width toward the top  1040  of the post  1030 , and its minimum medial-lateral or horizontal width toward the base  1038  of the post  1030 . The post  1030  may also be bilaterally symmetrical from the anterior and/or posterior perspectives. A recess  1045  may be formed posterior to the central portion  1028 , between the medial and lateral articulation portions  1024 ,  1026 , and may provide room for a posterior cruciate ligament (not shown). The PS insert  1012  may further include an insert base  1046 , which may further include an engagement feature  1048  for engagement with a tibial baseplate component. 
     Continuing with  FIGS. 14-16D , the post  1030  may have an articulation surface  1031  extending around the post  1030  on the medial, posterior, lateral, and anterior aspects of the post  1030 . The articulation surface  1031  may include a medial articulation surface  1032 , a lateral articulation surface  1034 , an anterior post surface  1036 , and a posterior articulation surface  1042 . The medial and lateral articulation surfaces  1032 ,  1034  may be non-parallel to one another and taper inward from the post superior end  1040  to the post base  1038  relative to an insert midline vertical axis  1002 , as shown in  FIGS. 16A and 16B . As shown in  FIG. 16A , an angle θ between the vertical axis  1002  and each tapered surface  1032 ,  1034  may be about 6.5°, in at least one embodiment. Since the post  1030  may be bilaterally symmetrical, the angle θ may be the same on both the medial and lateral sides  1032 ,  1034  of the post  1030 . In other embodiments of the disclosure, angle θ may range from about 6° to 11° degrees. The medial articulation surface  1032  may be continuous with the medial condylar articulation surface  1025 , and the lateral articulation surface  1034  may be continuous with the lateral condylar articulation surface  1027 . The anterior post surface  1036  may extend between the medial and lateral surfaces  1032 ,  1034  and may be convexly rounded. The anterior post surface  1036  may also taper outward from the post superior end  1040  to the post base  38  relative to the insert midline vertical axis  1002 , as best seen in  FIG. 16D . In other embodiments of the PS insert  1012 , the anterior post surface  1036  may include less taper, more taper, and/or no taper. A midline medial-lateral axis  1004  and a mid-line anterior-posterior axis  1006  are also shown. 
     Referring to  FIG. 16C , the boundary of the superior end  1040  may define a rounded rim  1044  shaped as a portion of a circle defined by a circular envelope  1047 , as seen from a superior perspective. The superior end  1040  and rim  1044  may have a convex protrusion  1041  toward a posterior end of the post  1030  as shown, and may permit passage of the posterior cruciate ligament. The circular superior end  1040  with rim  1044  may provide increased rotational range of motion and surface contact against the femoral component  1014  in comparison to traditional posts with a more square or rectangular shape and no rim. Thus, the rounded superior end  1040  and rim  1044  may allow for greater surface contact with the femoral component  1014  in contrast to the mere point or edge contact that is achieved by traditional posts that do not have these features. 
     The PS femoral component  1014  depicted in  FIGS. 14-15  may include augment fixation apertures  1080 , impact driver apertures  1090 , a cam element or cam bar  1050 , and a box structure  1052  for providing posterior stabilization in place of absent ligaments. The cam bar  1050  may include a cam articulating surface  1051  which may contact the posterior articulation surface  1042  of the post  1030  during flexion. An internal articulation surface  1054  may reside on the inside of the box structure  1052  and may contact the post  1030  during articulation and rotation of the knee joint. The internal articulating surface  1054  may be concavely curved, and may contact the rim  1044  of the post  1030  during axial rotation of the knee joint about the post  1030 . The PS femoral component  1014  may further include a medial condyle  1060  having a medial condylar articulation surface  1062 , and a lateral condyle  1064  having a lateral condylar articulation surface  1066 . The medial and lateral condylar articulation surfaces  1062 ,  1066  may articulate against the PS insert  1012  medial and lateral articulation surfaces  1025 ,  1027  respectively. A gap  1068  may be formed between the medial and lateral condyles  1060 ,  1064 , with the cam bar  1050  extending medial-laterally across the gap  1068 . The internal articulation surface  1054  may include a medial portion  1070  continuous with a lateral portion  1072 . In the embodiment depicted, a fixation post  1074  may protrude superiorly from the PS femoral component  1014 . However, in other embodiments of the PS femoral component  1014 , the fixation post  1074  may be absent and/or other fixation features such as posts, spikes, pegs, webs, keels or teeth may be present to affix the PS femoral component  1014  to a prepared femur (not shown). 
     Referring to  FIGS. 17 and 18 , another assembly  1110  embodiment of the disclosure may include the PS insert  1012  of  FIGS. 14-16D  coupled with a cruciate retaining femoral component  1114  (or “CR femoral component”). The CR femoral component  1114  may include a keel  1120 , fixation members  1130 , impact driver apertures  1190 , and medial and lateral condyles  1160 ,  1164  with a gap  1168  formed between the condyles  1160 ,  1164 . As a CR femoral component  1114 , no cam bar or box may be present. The condyles  1160 ,  1164  may include medial and lateral condylar articulation surfaces  1162 ,  1166 , and an internal articulation surface  1154  with medial and lateral portions  1170 ,  1172 . 
     The tapered sides  1032 ,  1034  of the post  1030  may permit natural articulation of the CR femoral component  1114  with the PS insert  1012 , which may not be achievable if the post  1030  were not tapered. For example, if the post  1030  had straight sides instead of tapered sides, the wider width of the post  1030  at the base of the post  1030  may interfere with the internal articulating surfaces  1170 ,  1172  of the condyles  1160 ,  1164 . When the PS femoral component  1014  is coupled with the PS insert  1012  to form assembly  1010 , as in  FIGS. 14 and 15 , the circular shape of the post superior end  1040  in combination with the tapered medial and lateral surfaces  1032 ,  1034  of the post  1030 , may permit the PS femoral component  1014  to articulate relative to the PS insert  1012  in the manner of a posterior stabilized femoral component. However, when the PS insert  1012  is paired and implanted with the CR femoral component  1114 , the resultant assembly  1110  may provide the native articulation and rotation of a cruciate retaining implant. 
     Referring to  FIGS. 19 and 20 , another assembly  2110  embodiment of the disclosure may include the PS insert  1012  of  FIGS. 14-16D  coupled with a cruciate retaining femoral component  2114  (or “CR femoral component”). The CR femoral component  2114  may not include a keel, as opposed to the CR femoral component  1114  shown in  FIGS. 17 and 18 , and the CR femoral component  2114  may be configured for cemented and/or cementless fixation to a femoral bone. The CR femoral component  2114  may include fixation members  2130 , impact driver apertures  2190 , and medial and lateral condyles  2160 ,  2164  with a gap  2168  formed between the condyles  2160 ,  2164 . As a CR femoral component  2114 , no cam bar or box may be present. The condyles  2160 ,  2164  may include medial and lateral condylar articulation surfaces  2162 ,  2166 , and an internal articulation surface  2154  with medial and lateral portions  2170 ,  2172 . 
     The tapered sides  1032 ,  1034  of the post  1030  may permit natural articulation of the CR femoral component  2114  with the PS insert  1012 , which may not be achievable if the post  1030  were not tapered. For example, if the post  1030  had straight sides instead of tapered sides, the wider width of the post  1030  at the base  1038  of the post  1030  may interfere with the internal articulating surfaces  2170 ,  2172  of the condyles  2160 ,  2164 . When the PS femoral component  1014  is coupled with the PS insert  1012  to form assembly  1010 , as in  FIGS. 14 and 15 , the circular shape of the post superior end  1040  in combination with the tapered medial and lateral surfaces  1032 ,  1034  of the post  1030 , may permit the PS femoral component  1014  to articulate relative to the PS insert  1012  in the manner of a posterior stabilized femoral component. However, when the PS insert  1012  is paired and implanted with the CR femoral component  2114 , the resultant assembly  2110  may provide the native articulation and rotation of a cruciate retaining implant. 
     Referring to  FIGS. 21A-21E , an alternative embodiment of a tibial insert  1212  is shown. The tibial insert  1212  may be referred to as a cruciate retaining tibial insert  1212  (or “CR insert”). In a system of the disclosure, the CR insert  1212  may be implanted with the CR femoral components  114 ,  1114 ,  2114  and a tibial baseplate component (not shown) to form a cruciate retaining knee prosthesis system. The CR insert  1212  may include a fixation side  1220 , which may be an inferior side, opposite an articulation side  1222 , which may be a superior side. The articulation side  1222  may include a medial articulation portion  1224  having a medial condylar articulation surface  1225  and a lateral articulation portion  1226  having a lateral condylar articulation surface  1227 . A central portion  1228  may separate the medial articulation portion  1224  from the lateral articulation portion  1226 . A recess  1245  may be formed posterior to the central portion  1228 , between the medial and lateral articulation portions  1224 ,  1226 , and may provide room for a posterior cruciate ligament. The CR insert  1212  may further include an insert base  1246  and an engagement feature  1248  for engagement with a tibial baseplate component. 
     The CR insert  1212  may be coupled with CR femoral components  114 ,  1114 ,  2114  to form a cruciate retaining assembly. This cruciate retaining assembly may be implanted with a suitable tibial baseplate as a complete cruciate retaining knee prosthesis. The CR insert  1212  may also be coupled with PS femoral components  14 ,  1014  to form a posterior stabilizing assembly and implanted with a suitable tibial baseplate as a complete posterior stabilizing knee prosthesis. 
     Referring to  FIGS. 22A-22F , another alternative embodiment of a tibial insert  1312  is shown. The tibial insert  1312  may be referred to as a constrained condylar knee (CCK) tibial insert  1312  (or “CCK insert”). The CCK insert  1312  may include a fixation side  1320 , which may be an inferior side, opposite an articulation side  1322 , which may be a superior side. The articulation side  1322  may include a medial articulation portion  1324  having a medial condylar articulation surface  1325  and a lateral articulation portion  1326  having a lateral condylar articulation surface  1327 . A central portion  1328  may separate the medial articulation portion  1324  from the lateral articulation portion  1326 . A post  1330  may protrude superiorly from the central portion  1328 , and extend from a post base  1338  to a top, or post superior end  1340 . From the anterior perspective, as shown in  FIG. 22E , and the posterior perspective, as shown in  FIG. 22D , the post  1330  may have its maximum medial-lateral or horizontal width at the post superior end  1340  of the post  1330 , and its minimum medial-lateral or horizontal width at the post base  1338  of the post  1330 . The post  1330  may be bilaterally symmetrical from the anterior and posterior perspectives. The CCK insert  1312  may further include a posterior recess  1345 , an insert base  1346 , and an engagement feature  1348  for engagement with a tibial tray (not shown). An opening  1350  may be present in the superior surface of the post  1330 . 
     The post  1330  may have an articulation surface  1331  extending around the post  1330  on the medial, posterior, lateral, and anterior aspects of the post  1330 . The articulation surface  1331  may include a medial articulation surface  1332 , a lateral articulation surface  1334 , an anterior post surface  1336 , and a posterior articulation surface  1342 . The medial and lateral articulation surfaces  1332 ,  1334  may taper slightly inward from the post superior end  1340  to the post base  1338  of the post  1330  relative to an insert midline vertical axis  1302 . However, some embodiments of CCK insert  1312  may include less taper, more taper, and/or no taper of the medial and lateral articulation surfaces  1332 ,  1334 . The medial articulation surface  1332  may be continuous with the medial condylar articulation surface  1325 , and the lateral articulation surface  1334  may be continuous with the lateral condylar articulation surface  1327 . The anterior post surface  1336  may extend between the medial and lateral articulation surfaces  1332 ,  1334  and may be convexly rounded. The anterior post surface  1336  may taper outward from the post superior end  1340  to the post base  1338  relative to the midline axis  1302 , as best seen in  FIG. 22F . In other embodiments of the CCK insert  1312 , the anterior post surface  1336  may include less taper, more taper, and/or no taper. The post  1330  of the CCK insert  1312  may be wider and bigger in diameter than the post  30  of PS insert  12 , for example to provide increased stability in the case of removal of the collateral ligaments. A midline medial-lateral axis  1304  and a mid-line anterior-posterior axis  1306  are also shown in  FIGS. 22D through 22F . 
     Referring to  FIG. 22B , the boundary of the post superior end  1340  may define a rounded rim  1344  shaped as a portion of a circle, from a superior perspective, and may have a convex protrusion toward a posterior end of the post  1330 . The post superior end  1340  and rim  1344  may be semi-circular as shown, however the rim  1344  may define a circular envelope  1347 . The post superior end  1340  may be circular and the rim  1344  may provide increased surface contact and rotational range of motion when coupled and implanted with the PS femoral components disclosed herein in comparison to traditionally shaped posts with a more square or rectangular shaped post. Thus, the rounded post superior end  1340  and rim  1344  may allow for greater surface contact with the femoral components  14 ,  1014  in contrast to the mere point or edge contact that is achieved by traditional posts that do not include these features. 
     The CCK insert  1312  may be coupled with the PS femoral components  14 ,  1014  to form a constrained condylar knee assembly, and this assembly may be implanted with a suitable tibial baseplate as a constrained condylar knee prosthesis. The CCK insert  1312  may also be coupled with any of the CR femoral components disclosed herein and implanted with a suitable tibial baseplate. Thus, all of the tibial inserts disclosed herein are interchangeable with all of the CR and PS femoral components disclosed herein. 
     Any of the tibial inserts, CR femoral components, and/or PS femoral components disclosed herein may be grouped together in any number or combination as one or more modular knee replacement systems or kits. A particular kit may include a CR femoral component, a PS insert, and a CR insert. Yet another particular kit may include a PS femoral component, a PS insert, a CR insert, and a CCK insert. Suitable tibial baseplate components may also be included with any kit. Moreover, any of the tibial inserts disclosed herein may be formed of vitamin E polyethylene, highly cross linked polyethylene, ultra-high molecular weight polyethylene (UHMWPE), and/or the like. 
     In an example method of the disclosure, a patient may initially experience compromise of the anterior cruciate ligament. The ACL may be removed, and a CR type prosthesis may be implanted, including a CR femoral component, a CR insert, and a tibial baseplate component. Later, the same patient may experience compromise of the PCL and may need additional stabilization of the knee joint. The PCL may be removed, the CR tibial insert may be removed, and a PS tibial insert of the disclosure may be inserted between the originally implanted CR femoral component and the tibial baseplate component, thus providing additional stability for the missing PCL. Even later, the same patient may experience instability of the collateral ligaments. The PS tibial insert may be removed, and the CCK tibial insert of the disclosure may be inserted between the originally implanted CR femoral component and the tibial baseplate component. Thus, the patient may progress from a CR knee prosthesis, to a PS knee prosthesis, and finally to a CCK knee prosthesis without requiring replacement of the originally implanted femoral and/or tibial baseplate components. The interchangeability of the inserts permits replacement of only the tibial insert component in order to provide increasing levels of support and stability to the knee joint. 
     In another example method of the disclosure, a patient may initially experience compromise of both the ACL and the PCL. These ligaments may be removed, and a PS type prosthesis may be implanted, including a PS femoral component, a PS insert, and a tibial baseplate component. Later, the same patient may experience instability of the collateral ligaments. The PS insert may be removed, and a CCK insert may be inserted between the originally implanted PS femoral component and the tibial baseplate component. Thus, the patient may progress from a PS knee prosthesis to a CCK knee prosthesis without requiring replacement of the originally implanted PS femoral component and tibial baseplate component. 
     Referring now to  FIGS. 23A-B ,  FIG. 23A  is a perspective front view of the femoral component  1014  of  FIG. 14  coupled to one or more augments  1082 ,  1084  of the present disclosure and  FIG. 23B  is a medial side view of the femoral component  1014  of  FIG. 23A . As briefly mentioned above with reference to  FIGS. 14 and 15 , the femoral component  1014  may include augment fixation apertures  1080  that may be configured to secure the one or more augments  1082 ,  1084  to the femoral component  1014 , as well as impact driver apertures  1090  configured to receive a femoral component impact driver tool (not shown) to allow a surgeon to press fit the femoral component  1014  to the end of a prepared femur. The augments  1082 ,  1084  may be secured to the femoral component  1014  with fixation members  1086  and the augments  1082 ,  1084  may generally act to replace missing and/or compromised femoral bone and allow the femoral component  1014  to be adequately secured to a femoral bone under such conditions. 
     Referring now to  FIGS. 24A-H , a femoral trial component  400  of the disclosure is illustrated in  FIGS. 24A-H . In particular,  FIG. 24A  shows a perspective top view of a femoral trial component of the disclosure,  FIG. 24B  shows a perspective rear view of the femoral trial component of  FIG. 24A ,  FIG. 24C  shows a lateral side view of the femoral trial component of  FIG. 24A ,  FIG. 24D  shows a medial side view of the femoral trial component of  FIG. 24A ,  FIG. 24E  shows an anterior view of the femoral trial component of  FIG. 24A ,  FIG. 24F  shows a posterior view of the femoral trial component of  FIG. 24A ,  FIG. 24G  shows a superior view of the femoral trial component of  FIG. 24A , and  FIG. 24H  shows an inferior view of the femoral trial component of  FIG. 24A . 
     The femoral trial component  400  may be referred to as a universal femoral trial component  400  because the femoral trial component  400  may be used as part of a universal femoral trial system for preparing and trialing a femoral bone of a patient (not shown) to receive a plurality of different femoral implant types, as will be discussed in more detail below. The femoral trial component  400  may include a medial condyle  410  having a medial condylar articulation surface  412 , a lateral condyle  420  having a lateral condylar articulation surface  422 , an attachment aperture  440  located intermediate the medial condyle  410  and the lateral condyle  420 , a patellar projection  430  located anterior to the medial condyle  410  and the lateral condyle  420 , a patellar articulation surface  432 , fixation member drill apertures  470 , impact driver apertures  480 , medial attachment features  450  proximate the medial condyle  410 , and lateral attachment features  460  proximate the lateral condyle  420 . The medial attachment features  450  may further include a medial attachment projection  452 , a medial attachment aperture  454  formed within the medial attachment projection  452 , and a medial attachment recess  456 . The lateral attachment features  460  may likewise include a lateral attachment projection  462 , a lateral attachment aperture  464  formed within the lateral attachment projection  462 , and a lateral attachment recess  466 . 
     In practice, the femoral trial component  400  may be coupled to a partially prepared distal end of a femur (not shown). For example, a partially prepared distal end of a femur may include five distal cuts that are made to the distal end of the femur using standard techniques and tools (not shown) that are well known in the art. These five cuts may be made to correspond in both shape and angle to the five surfaces on the inner portion of the femoral trial component  400 , as best seen in  FIGS. 24C and 24D . The femoral trial component  400  may then be press fit onto the partially prepared distal end of the femur and the femoral trial component  400  may also be aligned relative to the distal end of the femur in the medial-lateral directions. The femoral trial component  400  may then be used to further prepare the distal end of the femur and/or perform one or more trial operations with the femoral trial component  400  still in place on the distal end of a femur. 
     For example, the attachment aperture  440  formed in the femoral trial component  400 , along with the medial and lateral attachment features  450 ,  460 , may be configured to receive any of a plurality of removably couplable femoral bone preparation attachments and/or any of a plurality of femoral trial attachments. Example femoral bone preparation attachments may include a posterior stabilizing notch cutting guide assembly  500 , an augment cutting guide assembly (not shown), and a drill and broach guide assembly  700 , as will be discussed in more detail below. Each of these femoral bone preparation attachments may be configured to removably couple to the universal femoral trial component  400  to allow a femoral bone of a patient to be selectively modified and prepared to receive a selected femoral implant type. Example femoral trial attachments may include a cruciate retaining trial attachment  800  including a cruciate retaining central portion articulation surface  810  and a posterior stabilizing trial attachment  600  including a posterior stabilizing central portion articulation surface  610 , as will be discussed in more detail below. The cruciate retaining trial attachment  800  and the posterior stabilizing trial attachment  600  may each be configured to removably couple to the universal femoral trial component  400  to provide a central portion articulation surface  610 ,  810  above the attachment aperture  440  and allow for trialing of an articulation surface for a selected femoral implant type that includes a medial condylar articulation surface, a lateral condylar articulation surface, and a central portion articulation surface, for the selected femoral implant type. In this manner, the femoral bone preparation attachments and the femoral trial attachments may be used to help finish preparing the femur of the patient to receive any type of femoral component disclosed herein, and/or further perform one or more trial operations with the femoral trial component  400  still in place on the femur, as will be discussed in more detail below. 
     The femoral trial component  400  shown in  FIGS. 24A-H  is a right side femoral trial component  400  having a patellar projection  430  with a right angled medial-lateral shape, as best seen in  FIGS. 24E and 24F , which mimics the patellar region of a right femur (not shown). Note how the patellar projection  430  angles towards the right in the posterior view of the femoral trial component  400  shown in  FIG. 24F  and towards the left in the anterior view of the femoral trial component  400  shown in  FIG. 24E . A left side femoral trial component (not shown) will have a patellar projection  430  shape that is a mirror image of that shown in  FIGS. 24E and 24F , having a left angled medial-lateral shape that mimics the patellar region of a left femur (not shown). In another embodiment of the disclosure illustrated in  FIGS. 35A-C , a universal femoral trial component  900  may include a patellar projection  910  with a universal shape that does not angle towards the right or left, but rather, the patellar projection  910  in this embodiment may have a symmetrical medial-lateral shape. In this manner, the universal femoral trial component  900  shown in  FIGS. 35A-C  has a universal shape that may be used to prepare and trial both right and left side femurs. The patellar projection  910  may have a patellar articular surface  912 . 
       FIGS. 25A-26  illustrate a posterior stabilizing notch cutting guide assembly  500  that may be used with the femoral trial component  400  shown in  FIGS. 24A-H  to help prepare a femur of a patient to receive a PS femoral component of the present disclosure by guiding bone resection. In particular,  FIG. 25A  is a perspective rear view of the posterior stabilizing notch cutting guide assembly  500 ,  FIG. 25B  is another perspective rear view of the posterior stabilizing notch cutting guide assembly  500 ,  FIG. 25C  is a medial side view of the posterior stabilizing notch cutting guide assembly  500 ,  FIG. 25D  is a top view of the posterior stabilizing notch cutting guide assembly  500 , and  FIG. 26  is a partial exploded view of the posterior stabilizing notch cutting guide assembly  500 . 
     The posterior stabilizing notch cutting guide assembly  500  may include a posterior stabilizing notch cutting guide body  510  that includes a medial member  520  having a medial cutting guide surface  522  and medial channels  524  formed therein, a lateral member  530  having a lateral cutting guide surface  532  and lateral channels  534  formed therein, and a patellar member  540  having a patellar cutting guide surface  542 . 
     The posterior stabilizing notch cutting guide assembly  500  may also include a locking mechanism which may include: a first locking member  552 , a second locking member  554 , a first release lever  562  coupled to the first locking member  552  via a first pin  572 , a second release lever  564  coupled to the second locking member  554  via a second pin  574 , a first resilient member  592  located between the first release lever  562  and the posterior stabilizing notch cutting guide body  510 , with the first resilient member  592  housed in a first resilient member housing  582 , a second resilient member (not shown) similarly located between the second release lever  564  and the posterior stabilizing notch cutting guide body  510 , with the second resilient member housed in a second resilient member housing  584 . 
     The first resilient member  592  may be configured to apply a biasing force that acts to push the first locking member  552  away from the posterior stabilizing notch cutting guide body  510  in the medial direction and the second resilient member may be configured to apply a biasing force that acts to push the second locking member  554  away from the posterior stabilizing notch cutting guide body  510  in the lateral direction. 
     Referring to  FIGS. 27A and 27B , the posterior stabilizing notch cutting guide assembly  500  may be removably coupled to the universal femoral trial component  400  by squeezing the first release lever  562  and the second release lever  564  together toward each other (see arrows  501  in  FIG. 27A ) in order to overcome the biasing forces of the first resilient member  592  and the second resilient member; then inserting the posterior stabilizing notch cutting guide assembly  500  into the attachment aperture  440  of the universal femoral trial component  400  (see arrow  502  in  FIG. 27A ); and finally releasing the first release lever  562  and the second release lever  564  to allow the biasing forces of the first resilient member  592  and the second resilient member to push the first locking member  552  and the second locking member  554  away from the posterior stabilizing notch cutting guide body  510 , causing the first locking member  552  to enter within the medial attachment aperture  454  of the femoral trial component  400  and the second locking member  554  to enter within the lateral attachment aperture  464  of the femoral trial component  400  to couple the posterior stabilizing notch cutting guide assembly  500  to the universal femoral trial component  400 , as shown in  FIG. 27B . 
       FIGS. 28A-D  illustrate a posterior stabilizing trial attachment  600  that may be used with the femoral trial component  400  shown in  FIGS. 24A-H  to aid performance of one or more trial operations with the femoral trial component  400  in place on the distal end of the femoral bone. In particular,  FIG. 28A  is a perspective rear view of the posterior stabilizing trial attachment  600 ,  FIG. 28B  is another perspective rear view of the posterior stabilizing trial attachment  600 ,  FIG. 28C  is a perspective front view of the posterior stabilizing trial attachment  600 , and  FIG. 28D  is a perspective side view of the posterior stabilizing trial attachment  600 . 
     The posterior stabilizing trial attachment  600  may include a central portion articulation surface  610 , an internal articulation surface  620  having a medial portion  622  and a lateral portion  624 , a cam bar element  630  having a cam bar articulating surface  632 , a posterior stabilizing box  670 , and a gap  640  formed between the medial and lateral portions  622 ,  624  within the posterior stabilizing box  670 . Each of these components of the posterior stabilizing trial attachment  600 , such as the posterior stabilizing box  670  and the cam bar element  630 , may be configured to allow for trialing of a complete posterior stabilizing femoral implant. 
     The posterior stabilizing trial attachment  600  may also include attachment projections  650 ,  660  on the medial and lateral sides of the posterior stabilizing trial attachment  600 . The attachment projections  650 ,  660  may have shapes that are complementary to the medial and lateral attachment features  450 ,  460  and/or the medial and lateral attachment recesses  456 ,  466  that are formed in the femoral trial component  400 . In this manner, the attachment projections  650 ,  660  may be configured to couple to the medial and lateral attachment features  450 ,  460  and/or the medial and lateral attachment recesses  456 ,  466  formed in the femoral trial component  400 , as shown in  FIGS. 29A and 29B . This may be accomplished by holding the posterior stabilizing trial attachment  600  above the femoral trial component  400  and moving the posterior stabilizing trial attachment  600  toward the attachment aperture  440  formed in the universal femoral trial component  400  (see arrow  601  in  FIG. 29A ) until the posterior stabilizing trial attachment  600  is coupled to the femoral trial component  400 , as shown in  FIG. 29B . In at least one embodiment, the posterior stabilizing trial attachment  600  may be further configured to magnetically couple to the femoral trial component  400 . 
     In this manner, the posterior stabilizing trial attachment  600  may removably couple to the universal femoral trial component  400  and provide the central portion articulation surface  610  above the attachment aperture  440  of the femoral trial component  400  to allow for trialing of a complete articulation surface for a selected femoral implant type, such as a PS femoral component disclosed herein. A complete articulation surface may include a medial condylar articulation surface, a lateral condylar articulation surface, and the central portion articulation surface  610 , for the selected femoral implant type. 
       FIGS. 30A-31  illustrate a drill and broach guide assembly  700  that may be used with the femoral trial component  400  shown in  FIGS. 24A-H  to help prepare a femur of a patient to receive a femoral component of the present disclosure that utilizes a keel or other bone fixation member that may require a pre-drilled and/or broached bone aperture. In particular,  FIG. 30A  is a perspective rear view of the drill and broach guide assembly  700 ,  FIG. 30B  is a perspective bottom view of the drill and broach guide assembly  700 ,  FIG. 30C  is a top view of the drill and broach guide assembly  700 ,  FIG. 30D  is a bottom view of the drill and broach guide assembly  700 , and  FIG. 31  is a partial exploded view of the drill and broach guide assembly  700 . 
     The drill and broach guide assembly  700  may include a drill and broach guide body  710 , attachment projections  750 ,  760 , and a drill and broach guide  720 . The drill and broach guide  720  may further include a first drill guide aperture  721 , a second drill guide aperture  722 , a third drill guide aperture  723 , a first broach guide aperture  725  intermediate the first drill guide aperture  721  and the second drill guide aperture  722 , and a second broach guide aperture  726  intermediate the second drill guide aperture  722  and the third drill guide aperture  723 . The second drill guide aperture  722  may also be located intermediate the first broach guide aperture  725  and the second broach guide aperture  726 . 
     The drill and broach guide assembly  700  may also include a drill and broach guide locking mechanism which may include: a first locking member  742 , a second locking member  744 , a first release lever  732  coupled to the first locking member  742  via a first pin  752 , a second release lever  734  coupled to the second locking member  744  via a second pin  754 , and a resilient member  770  located between the first locking member  742  and the second locking member  744  within a locking member housing  780  formed within the drill and broach guide body  710 . The resilient member  770  may be configured to apply a biasing force between the first locking member  742  and the second locking member  744  to push the first locking member  742  and the second locking member  744  away from each other. 
     Referring to  FIGS. 32A and 32B , the drill and broach guide assembly  700  may be removably coupled to the universal femoral trial component  400  by squeezing the first release lever  732 , and the second release lever  734  together toward each other (see arrows  701  in  FIG. 32A ) in order to overcome the biasing force of the resilient member  770  between the first locking member  742  and the second locking member  744 ; then inserting the drill and broach guide assembly  700  into the attachment aperture  440  formed in the universal femoral trial component  400  (see arrow  702  in  FIG. 32A ); and finally releasing the first release lever  732  and the second release lever  734  to allow the biasing force of the resilient member  770  to push the first locking member  742  and the second locking member  744  away from each other, causing the first locking member  742  to enter within the medial attachment aperture  454  of the femoral trial component  400  and the second locking member  744  to enter within the lateral attachment aperture  464  of the femoral trial component  400  to couple the drill and broach guide assembly  700  to the universal femoral trial component  400 , as shown in  FIG. 32B . The attachment projections  750 ,  760  may also have shapes that are complementary to the medial and lateral attachment features  450 ,  460  and/or the medial and lateral attachment recesses  456 ,  466  formed in the femoral trial component  400  to aid coupling of the drill and broach guide assembly  700  to the universal femoral trial component  400 , as well as magnetic coupling capabilities. 
       FIGS. 40-44  illustrate an embodiment of a drill and broach guide assembly  1790  that may be used with the femoral trial component  400  shown in  FIGS. 24A-H  to help prepare a femur of a patient to receive a femoral component of the present disclosure that utilizes a keep or other bone fixation member, which may require a pre-drilled and/or broached bone aperture. In particular,  FIG. 40  is a perspective view of the drill and broach guide assembly  1790 ,  FIG. 41  is a side perspective view of the drill and broach guide assembly  1790 ,  FIG. 42  is a bottom view of the drill and broach guide assembly  1790 ,  FIG. 43  is a partial exploded view of the drill and broach guide assembly  1790 , and  FIG. 44  is a partial exploded bottom perspective of the drill and broach guide assembly  1790 . 
     The drill and broach guide assembly  1790  may include a drill and broach guide body  1710 , attachment projections  1760  on opposing sides of the body  1710 , and a drill and broach guide  1720 . The drill and broach guide  1720  may further include a first drill guide aperture  1721 , a second drill guide aperture  1722 , a third drill guide aperture  1723 , a first broach guide aperture  1725  intermediate the first drill guide aperture  1721  and the second drill guide aperture  1722 , and a second broach guide aperture  1726  intermediate the second drill guide aperture  1722  and the third drill guide aperture  1723 . The second drill guide aperture  1722  may also be located intermediate the first broach guide aperture  1725  and the second broach guide aperture  1726 . 
     The drill and broach guide assembly  1790  may also include a drill and broach guide locking mechanism. The locking mechanism may include a handle  1700 , with a grip  1701 , a base  1702 , a track  1703 , and a handle tab connection  1704 . The handle  1700  fits within a cavity  1770  in the body  1710  of the drill and broach guide, so that the handle tab connections pass into the cavity  1770  and the base  1702  may rest on the body  1710 . The handle is attached to the body  1710  via pins  1711 . The handle is operationally connected to a first tab  1740  and a second tab  1741 . The first tab  1740  and the second tab  1741  are extendable from the base  1710  on opposing sides, as illustrated in  FIGS. 40 and 41 . 
     As illustrated in  FIG. 42 , the handle tab connection  1704  is visible in the cavity  1770 , in a bottom of the base  1710 . The handle tab connection  1704  is shown as two protrusions from the base  1702  of the handle  1700 , which engage tab apertures  1746  in the first tab  1740  and the second tab  1741 . However, it is understood that the handle tab connection  1704  may be any reasonable operational connection between the handle  1700  and the first tab  1740  and the second tab  1741 . Other operational connections may include protrusions on the first tab  1740  and the second tab  1741 , which engage with apertures on the handle  1700 . Operational connections may include belt or screw drives, or any combination of bosses, bushings, or other bearing surfaces. The handle tab connection  1704  engages and passes through proximal ends  1744  of the first tab  1740  and the second tab  1741 . A portion of the handle tab connections  1704 , passing through and protruding through the proximal ends  1744  of the first tab  1740  and the second tab  1741 , may engage rotation stops  1750  on the body  1710  at the edge of the cavity  1770 . The rotation stops  1750  oppose one another across the cavity  1770 , and are configured to limit the movement of the handle tab connection  1704  about an axis that passes through the cavity  1770 . The rotation stops  1750  are illustrated as bumps or protrusions but may have any structural configuration that limits movement of the handle  1700  about the axis. 
     The first tab  1740  and the second tab  1741  each have a proximal end  1744 , which is engaged with the handle  1700  as discussed above, a distal end  1743 , and a compressible section  1745  connecting the proximal end  1744  and the distal end  1743 . The first tab  1740  and the second tab  1741  are located within the body  1710  of the guide assembly  1790 , so that the proximal ends  1744  are nearest the cavity  1770  and the distal ends  1743  extend away from the cavity  1770 , as shown in  FIG. 42 . The compressible sections  1745  are depicted having spring-like configurations, but may have coiled or other resilient configurations. 
       FIGS. 43 and 44  illustrate more fully how the drill and broach guide  1790  is operationally connected. The handle  1700  may rotate relative to the body  1710  about the axis that passes through the cavity  1770 . The handle  1700  is secured to the body  1710  via an engagement between pins  1711 , the body  1710 , and the track  1703  of the handle  1700 . The pins  1711  each comprise a threaded section  1712  and a smooth section  1713 . The pins  1711  are configured to screw into pin holes  1714  in the body  1710 . The threaded sections  1712  engage with complementary threaded portions of the pin holes  1714 . When threaded in the pin holes  1744 , the smooth sections  1713  of the pins  1711  extend into the cavity  1770 . When the base  1702  of the handle  1700  is seated on the body  1710 , the track  1703  extends into the cavity  1770  and engages the smooth sections  1713  of the pins  1711 . The track  1703  and the smooth sections  1713  have complementary profiles, for example the track  1703  is concave and the smooth sections  1713  are convex, which rest in the track  1703 . The smooth sections  1713  engage with opposite sides of the track, which fixes the handle  1700  to the body  1710 , yet allows the handle  1700  to rotate about the axis. 
     The rotation of the handle  1700 , while operationally secured to the body  1710 , creates a camming action causing the first tab  1740  and the second tab  1741  to extend from or retract into corresponding tab recesses  1771  in opposing sides of the body  1710 . As the handle  1710  is turned, the handle tab connections  1704  act on the proximal ends  1744  of the first tab  1740  and second tab  1741  pushing the tabs  1740   1741  out of the body  1710 . The protruding portions of the handle tab connections  1704  abut the rotation stops  1750  preventing the handle from a complete rotation. The drill and broach guide assembly  1790  may be configured so that the handle tab connections  1704  abut the rotation stops  1750  when the first tab  1740  and the second tab  1741  are at a most-extended position, away from the body. The compressible section  1745  of the first tab  1740  and the second tab  1741  may be configured to apply a biasing force between the distal ends  1743  and the proximal ends  1744  ends of each of the tabs  1740   1741  and the handle  1700 . 
     In operation, the drill and broach guide assembly  1790  may be removably coupled to the universal femoral trial component  400  by inserting the drill and broach guide assembly  1790  into the attachment aperture  440  formed in the universal femoral trial component  400 , similar to what is shown in  FIG. 32A  represented by arrow  702 . The attachment projections  1760  may also have shapes that are complementary to the medial and lateral attachment features  450 ,  460  and/or the medial and lateral attachment recesses  456 ,  466  formed in the femoral trial component  400  to aid coupling of the drill and broach guide assembly  1790  to the universal femoral trial component  400 , as well as magnetic coupling capabilities. Once seated in the trial component, the handle  1700  may be rotated so that the first tab  1740  and the second tab  1741  are extended into the medial attachment aperture  454  and the lateral attachment aperture  464  of the femoral trial component  400 . As the tab distal ends  1743  abut walls of the attachment apertures  454   464 , the compressible sections  1745  begin to compress, creating the biasing force discussed above. The handle  1700  may be turned further so that the handle tab connections  1704  abut the rotation stops  1750 . The combination of the biasing force from the compressible sections  1745  in the medial attachment aperture  464  and the lateral attachment aperture  465  and the abutment of the handle tab connections against the rotation stops  1750 , causes the drill and broach guide assembly to lock in place in the femoral trial component. 
       FIGS. 33A-D  illustrate a cruciate retaining trial attachment  800  that may be used with the femoral trial component  400  shown in  FIGS. 24A-H  to aid performance of one or more trial operations with the femoral trial component  400  in place on the distal end of the femoral bone. In particular,  FIG. 33A  is a perspective front view of the cruciate retaining trial attachment  800 ,  FIG. 33B  is a perspective rear view of the cruciate retaining trial attachment  800 ,  FIG. 33C  is a perspective bottom view of the cruciate retaining trial attachment  800 , and  FIG. 33D  is a top view of the cruciate retaining trial attachment  800 . 
     The cruciate retaining trial attachment  800  may include a central portion articulation surface  810 , an internal articulation surface  820  having a medial portion  822  and a lateral portion  824 , and a gap  840  formed between the medial and lateral portions  822 ,  824 . Each of these components of the cruciate retaining trial attachment  800  may be configured to allow for trialing of a complete cruciate retaining femoral implant. 
     The cruciate retaining trial attachment  800  may also include attachment projections  850 ,  860  on the medial and lateral sides of the cruciate retaining trial attachment  800 . The attachment projections  850 ,  860  may have shapes that are complementary to the medial and lateral attachment features  450 ,  460  and/or the medial and lateral attachment recesses  456 ,  466  that are formed in the femoral trial component  400 . In this manner, the attachment projections  850 ,  860  may be configured to couple to the medial and lateral attachment features  450 ,  460  and/or the medial and lateral attachment recesses  456 ,  466  formed in the femoral trial component  400 , as shown in  FIGS. 34A and 34B . This may be accomplished by holding the cruciate retaining trial attachment  800  above the femoral trial component  400  and moving the cruciate retaining trial attachment  800  toward the attachment aperture  440  formed in the universal femoral trial component  400  (see arrow  801  in  FIG. 34A ) until the cruciate retaining trial attachment  800  is coupled to the femoral trial component  400 , as shown in  FIG. 34B . In at least one embodiment, the cruciate retaining trial attachment  800  may be further configured to magnetically couple to the femoral trial component  400 . 
     In this manner, the cruciate retaining trial attachment  800  may removably couple to the universal femoral trial component  400  and provide the central portion articulation surface  810  above the attachment aperture  440  of the femoral trial component  400  to allow for trialing of a complete articulation surface for a selected femoral implant type, such as a CR femoral component disclosed herein. A complete articulation surface may include a medial condylar articulation surface, a lateral condylar articulation surface, and the central portion articulation surface  810 , for the selected femoral implant type. 
     Any of the components disclosed herein may be included in a modular universal femoral trial kit (not shown) to aid in preparing and trialing a femoral bone of a patient to receive a plurality of different femoral implant types. In at least one embodiment, the modular universal femoral trial kit may include a container (not shown) that contains a femoral trial component  400 ,  900  and at least one femoral bone preparation attachment, such as the posterior stabilizing notch cutting guide assembly  500  and/or the drill and broach guide assembly  700 , as one non-limiting example. In other embodiments, the modular universal femoral trial kit may also include at least one femoral trial attachment, such as the cruciate retaining trial attachment  800  and/or the posterior stabilizing trial attachment  600 , as another non-limiting example. 
       FIG. 36  illustrates a flow chart diagram of a method  3000  for preparing and trialing a femoral bone with a universal femoral trial component  400 ,  900 , according to one embodiment of the present disclosure. The method  3000  will be described in connection with the components and instrumentation described herein. However, those of skill in the art will recognize that alternative implants, assemblies, systems, and instrumentation may be used in the performance of the method  3000 . 
     The method  3000  may begin with a step  3010  in which a universal femoral trial component  400 ,  900  may be placed on an inferior or distal end of a femoral bone. The distal end of the femoral bone may first be partially prepared with five distal cuts that are made to the distal end of the femur using standard techniques and tools (not shown) that are well known in the art. These five cuts may be made to correspond in both shape and angle to the five surfaces on the inner portion of the universal femoral trial component  400 ,  900  (e.g., see  FIGS. 24C and 24D ). The universal femoral trial component  400 ,  900  may then be press fit onto the partially prepared distal end of the femur. 
     In a step  3020 , the universal femoral trial component  400 ,  900  may be further aligned with respect to the femoral bone along a medial-lateral direction in order to place the universal femoral trial component  400 ,  900  at a desired medial-lateral location with respect to the femoral bone. 
     In a step  3030 , one of a plurality of femoral bone preparation attachments may be selected in order to guide resection of portions of the femoral bone, as desired. Example, femoral bone preparation attachments may include the posterior stabilizing notch cutting guide assembly  500  and the drill and broach guide assembly  700 , as two non-limiting examples. 
     In a step  3040 , the selected femoral bone preparation attachment may be coupled to the universal femoral trial component  400 ,  900  using techniques described previously herein (e.g., see description related to  FIGS. 27A-B  and  FIGS. 32A-B ). 
     In a step  3050 , the femoral bone may be prepared to receive a desired femoral component by using the selected femoral bone preparation attachment as a guide to resect at least a portion of the femoral bone in order to prepare the femoral bone to receive the desired femoral component. Once the femoral bone has been prepared with the selected femoral bone preparation attachment, the method may move to a step  3060 . 
     In the step  3060 , the selected femoral bone preparation attachment may be removed from the universal femoral trial component  400 ,  900 . 
     In a step  3070 , one of a plurality of femoral trial attachments may be selected in preparation for performing one or more trial operations with the universal femoral trial component  400 ,  900  still in place on the femoral bone. 
     In a step  3080 , the selected femoral trial attachment may be coupled to the universal femoral trial component  400 ,  900  using techniques described previously herein (e.g., see description related to  FIGS. 29A-B  and  FIGS. 34A-B ). 
     In a step  3090 , at least one trial operation may be performed with the selected femoral trial attachment coupled to the universal femoral trial component  400 ,  900 , and the method  300  may end. For example, the surgeon may perform trialing of articulation surfaces of the knee joint to ensure that the articulation characteristics of the prosthetic knee joint will be satisfactory. 
     Various steps of any method disclosed herein may be reordered, omitted, and/or replaced with different steps within the scope of the present disclosure. Those of skill in the art, with the aid of the present disclosure, will recognize that many variations may be made to any other method disclosed herein, depending on the particular surgical procedure to be carried out, as well as the configuration of the system used in the performance of that surgical procedure. Moreover, any methods disclosed herein may include one or more steps or actions for performing the described method. These method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order and/or use of specific steps and/or actions may be modified. 
       FIG. 37  illustrates a flow chart diagram of a method  4000  for revising a knee joint prosthesis implanted in a knee of a patient to provide increased stability to the knee joint prosthesis, according to one embodiment of the present disclosure. The method  4000  will be described in connection with the components and instrumentation described herein. However, those of skill in the art will recognize that alternative implants, assemblies, systems, and instrumentation may also be used in the performance of the method  4000 . 
     The method  4000  may begin with a step  4010 , in which a first knee joint prosthesis that is implanted in a knee of a patient is surgically accessed. The first knee joint prosthesis may comprise a first tibial insert that is located between a tibial base plate component that is implanted on a tibia of the patient and a femoral component that is implanted on a femur of the patient. 
     The method  4000  may then proceed to a step  4020 , in which the first tibial insert may be removed from between the tibial base plate component and the femoral component. 
     The method  4000  may then proceed to a step  4030 , in which a second tibial insert may be inserted between the tibial baseplate component and the femoral component to create a second knee joint prosthesis assembly that is more constrained that the first knee joint prosthesis assembly, and the method  4000  may end. 
       FIGS. 38A-F  and  39  illustrate an example tibial tray  5000  that may be used with any of the tibial inserts and femoral components described herein to create various prosthetic knee assemblies, according to embodiments of the present disclosure. In particular,  FIG. 38A  shows a perspective front view of the tibial tray  5000 ,  FIG. 38B  shows a perspective rear view of the tibial tray  5000 ,  FIG. 38C  shows an anterior view of the tibial tray  5000 ,  FIG. 12D  shows a posterior view of the tibial tray,  FIG. 38E  shows a bottom view of the tibial tray  5000 ,  FIG. 38F  shows a top view of the tibial tray  5000 , and  FIG. 39  shows an exploded view of an example tibial tray mounting system  6000  that utilizes the tibial tray  5000 . 
     The tibial tray  5000  may generally include a tibial base plate  5001  that is superiorly mounted on top of a keel  5030 . The tibial base plate  5001  may have a superior end  5010  configured to receive any of the tibial inserts described herein, and an inferior end  5020  configured to engage a superior surface of a prepared tibia of a patient (not shown). The superior end  5010  of the tibial base plate  5001  may include a posterior lip  5012  and an anterior lip  5014 , each configured to couple to and retain any of the tibial inserts described herein. The posterior lip  5012  may have a notch  5016  to permit passage of ligaments and/or other soft tissues. The superior end  5010  of the tibial base plate  5001  may also include a tibial insert retaining aperture  5050  configured to receive a tibial insert retaining rod  6010 , which may be used to further couple to and retain a suitable tibial insert to the tibial base plate  5001 , as shown in  FIG. 39 , provided the tibial insert has a corresponding opening in the post of the tibial insert configured to receive the tibial insert retaining rod  6010  (e.g., see the tibial insert shown in  FIGS. 22A-F ). 
     The inferior end  5020  of the tibial base plate  5001  may include one or more spikes  5040  configured to penetrate tibial bone to further couple the tibial base plate  5001  to the superior surface of a prepared tibia. The Keel  5030  may also include a medial fin  5032  and a lateral fin  5034  each configured to penetrate tibial bone and provide additional coupling of the tibial tray  5000  to the tibia. Moreover, in some embodiments the Keel  5030  may also include a tibial stem aperture  5036  configured to receive a tibial stem  6030  and/or a stem adapter member  6020  to further couple the tibial tray  5000  to the tibia of a patient (see  FIG. 39 ). The tibial stem  6030  may be configured to penetrate and reside within an intramedullary canal of the tibia to provide increased fixation of the tibial tray  5000  to the tibia. 
     It will be understood that the tibial tray  5000  and tibial tray mounting system  6000  shown in  FIGS. 38A-F  and  39  are merely one example of a tibial tray and tibial tray mounting system that may be used with the tibial inserts and femoral components described in the present disclosure and that other tibial trays and tibial tray mounting systems are also contemplated herein. 
     Reference throughout this specification to “an embodiment” or “the embodiment” means that a particular feature, structure or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, the quoted phrases, or variations thereof, as recited throughout this specification are not necessarily all referring to the same embodiment. 
     Similarly, it should be appreciated that in the above description of embodiments, various features are sometimes grouped together in a single embodiment, Figure, or description thereof for the purpose of streamlining the disclosure. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim require more features than those expressly recited in that claim. Rather, as the following claims reflect, inventive aspects lie in a combination of fewer than all features of any single foregoing disclosed embodiment. Thus, the claims following this Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment. This disclosure includes all permutations of the independent claims with their dependent claims. 
     The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated. 
     Recitation in the claims of the term “first” with respect to a feature or element does not necessarily imply the existence of a second or additional such feature or element. Elements recited in means-plus-function format are intended to be construed in accordance with 35 U.S.C. § 112 Para. 6. It will be apparent to those having skill in the art that changes may be made to the details of the above-described embodiments without departing from the underlying principles set forth herein. 
     The phrases “connected to,” “coupled to” and “in communication with” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components may be functionally coupled to each other even though they are not in direct contact with each other. The term “abutting” refers to items that are in direct physical contact with each other, although the items may not necessarily be attached together. The phrase “fluid communication” refers to two features that are connected such that a fluid within one feature is able to pass into the other feature. 
     The Figures may show simplified or partial views, and the dimensions of elements in the Figures may be exaggerated or otherwise not in proportion for clarity. In addition, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a terminal includes reference to one or more terminals. In addition, where reference is made to a list of elements (e.g., elements a, b, c), such reference is intended to include any one of the listed elements by itself, any combination of less than all of the listed elements, and/or a combination of all of the listed elements. 
     The term “substantially” means that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide. 
     As used herein, the term “proximal”, “top”, “up” or “upwardly” may refer to a location on the device that is closest to the clinician using the device and farthest from the patient in connection with whom the device is used when the device is used in its normal operation. Conversely, the term “distal”, “bottom”, “down” or “downwardly” may refer to a location on the device that is farthest from the clinician using the device and closest to the patient in connection with whom the device is used when the device is used in its normal operation. Moreover, the terms “upper” and “lower”, and “top” and “bottom”, “front” and “rear” may be used as relative terms herein for ease of description and understanding. It is understood that in embodiments of the disclosure, upper and lower entities may be reversed, as may top and bottom, front and rear. 
     As used herein, the term “in” or “inwardly” refers to a location with respect to the device that, during normal use, is toward the inside of the device. Conversely, as used herein, the term “out” or “outwardly” refers to a location with respect to the device that, during normal use, is toward the outside of the device. 
     While specific embodiments and applications of the present disclosure have been illustrated and described, it is to be understood that the scope of this disclosure is not limited to the precise configuration and components disclosed herein. Various modifications, changes, and variations which will be apparent to those skilled in the art may be made in the arrangement, operation, and details of the methods and systems of the present disclosure set forth herein without departing from it spirit and scope.