Patent Publication Number: US-9839521-B2

Title: Prosthetic knee implant

Description:
CLAIM OF PRIORITY 
     This application is a continuation of U.S. patent application Ser. No. 14/201,240, filed on Mar. 7, 2014, which claims the benefit of U.S. Provisional Patent Application Ser. No. 61/784,521, filed on Mar. 14, 2013, the benefit of priority of each of which is claimed hereby, and which are incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     Orthopedic prostheses are commonly utilized to prepare and/or replace damaged bone and tissue in the human body. For example, a prosthetic knee implant can be used to restore natural knee function by repairing damaged or diseased articular surfaces of a femur, a tibia, or both. Knee implants can include a femoral component implanted on the distal end of a femur, which articulates with a natural tibia or with a tibial component implanted on the corresponding proximal end of tibia. The femoral and tibial components can cooperate to restore the function of healthy natural knee. 
     Overview 
     This present disclosure is directed to knee implants and methods for implanting the knee implants. Using the knee implants and methods, a surgeon can achieve improved or optimal patella tracking while avoiding overhang of the femoral component. 
     The present inventors have recognized, among other things, that existing implants and methods can fail to provide a knee prosthesis with optimal patella tracking while minimizing or eliminating overhang of the femoral component relative to adjacent bone (e.g., the femur). A surgeon using an existing implant and method can shift a femoral component laterally, relative to what the instructions for use suggest, to attempt to allow a patella to track more laterally in flexion. However, a surgeon can be limited in how far the femoral component can be shifted laterally before the femoral component begins to overhang the femur. Therefore, in some instances the surgeon compromises between optimal patella tracking and avoiding overhang. The overhang can occur over the lateral periphery of the femoral bone or over the medial edge of the intercondylar notch and can be problematic for knee joint soft tissue. 
     The implants and methods of the present disclosure can provide or use a prosthetic knee implant comprising a femoral component. The femoral component can include a medial condyle and a lateral condyle, each of the condyles defining respective distal-most points and having substantially equal widths, as measured from a condyle medial side to a condyle lateral side and proximate the distal portion. The width of each of the condyles can define respective condyle midpoints located halfway between the condyle medial sides and the condyle lateral sides, where the distal-most points can be located laterally from the midpoints. The femoral component can further include a trochlear groove defining a distal-most sulcus point located halfway between the distal-most point of the medial condyle and the distal-most point of the lateral condyle. 
     The distal-most sulcus point of the trochlear groove can be shifted laterally with respect to the midpoint located halfway between the medial condyle and the lateral condyle midpoints. The lateralized trochlear groove can facilitate lateralization of the patella before further adjusting the femoral component laterally. Even if a surgeon decides to further lateralize the femoral component, the amount the femoral component of the present disclosure is further lateralized, to provide optimal patellar tracking, can be reduced or minimized, as compared to a femoral component that has a centralized distal-most sulcus point of the trochlear groove. 
     Additionally, the widths of the medial and lateral condyle can be substantially equal. The equal widths of the medial and lateral condyles can allow the intercondylar notch to remain centered between the medial and lateral condyles, while providing a lateralized trochlear groove. Maintaining the centrality of the intercondylar notch can enable a surgeon to make an intercondylar box cut more central (e.g., less laterally) on the femur, as compared to a femoral component with a lateralized intercondylar notch. If the intercondylar box cut is shifted laterally, as with other approaches to knee implants, the risk of a fracture across the lateral condylar bridge of the femur can increase. Therefore, the knee implants and methods of the present disclosure can advantageously reduce patellar maltracking, reduce or minimize or eliminate overhang, and reduce the risk of fracture. 
     To better illustrate examples of the prosthesis knee implants and methods disclosed herein, a non-limiting list of examples is provided here: 
     In Example 1, a prosthetic knee implant comprises a femoral component having a femur-contacting surface, an opposing articulation surface, and proximal, distal, anterior and posterior portions. The femoral component can include a medial condyle and a lateral condyle, each of the condyles defining respective distal-most points and having substantially equal widths, as measured from a condyle medial side to a condyle lateral side and proximate the distal portion. The width of each of the condyles defining respective condyle midpoints halfway between the condyle medial sides and the condyle lateral sides, the distal-most points located laterally from the midpoints. The femoral component can include a trochlear groove, proximate the anterior portion, defining a distal-most sulcus point located halfway between the distal-most point of the medial condyle and the distal-most point of the lateral condyle. 
     In Example 2, the implant of Example 1 is optionally configured such that the distal-most point of the medial condyle is located laterally at a first distance from the medial condyle midpoint and the distal-most point of the lateral condyle is located laterally at a second distance, equal to the first distance, from the lateral condyle midpoint. 
     In Example 3, the implant of Examples 1 or 2 is optionally configured such that the first distance and the second distance are between 1.0 millimeter and 4.0 millimeters, inclusive. 
     In Example 4, the implant of any one or any combination of Examples 1-3 is optionally configured such that the trochlear groove defines a patellar axis, when viewed from an anterior side of the femoral component, oriented substantially perpendicular to a plane connecting the distal-most point of the medial condyle and the distal-most point of the lateral condyle. 
     In Example 5, he implant of any one or any combination of Examples 1-4 is optionally configured such that the trochlear groove defines a patellar axis, when viewed from an anterior side of the femoral component, oriented substantially perpendicular to a plane connecting the medial condyle midpoint and the lateral condyle midpoint. 
     In Example 6, the implant of any one or any combination of Examples 1-5 is optionally configured such that the width of each of the condyles is between 19 millimeters and 31 millimeters, inclusive. 
     In Example 7, the implant of any one or any combination of Examples 1-6 optionally further includes a box-like projection extending from the femur-contacting surface and located halfway between the medial condyle midpoint and the lateral condyle midpoint. 
     In Example 8, the implant of any one or any combination of Examples 1-7 optionally further includes a concave surface extending between the medial and lateral condyles, the concave surface defining a proximal-most point halfway between the medial condyle distal-most point and the lateral condyle distal-most midpoint. 
     In Example 9, the implant of any one or any combination of Examples 1-8 optionally further includes a tibial component having a tibial-contacting surface, an opposing articulation surface, and proximal and distal portions. 
     In Example 10, the implant of any one or any combination of Examples 1-9 is optionally configured such that the articulation surface includes a medial dished surface portion and a lateral dished surface portion, each of the dished surface portions defining respective distal-most points and widths, as measured from a surface portion medial side to a surface portion lateral side, the width of each of the dished surface portions defining respective dished surface portion midpoints halfway between the surface portion medial sides and the surface portion lateral sides, the distal-most points located laterally from the midpoints. 
     In Example 11, the implant of any one or any combination of Examples 1-10 is optionally configured such that the distal-most point of the medial dished surface portion is located laterally a third distance from the medial dished surface portion midpoint and the distal-most point of the lateral dished surface portion is located laterally a fourth distance, equal to the third distance, from the lateral dished surface portion midpoint. 
     In Example 12, the implant of any one or any combination of Examples 1-11 is optionally configured such that the first and second distances are equal to the third and fourth distances. 
     In Example 13, the implant of any one or any combination of Examples 1-12 is optionally configured such that the medial dished surface portion and the lateral dished surface portion are asymmetrical, when viewed from a posterior side of the tibial component. 
     In Example 14, the implant of any one or any combination of Examples 1-13 is optionally configured such that the medial dished surface portion and the lateral dished surface portion are symmetrical, when viewed from a posterior side of the tibial component. 
     In Example 15, the implant of any one or any combination of Examples 1-14 is optionally configured such that the tibial component further comprises a tibial post extending from the articulation surface and located halfway between the medial dished surface portion midpoint and the lateral dished surface portion midpoint. 
     In Example 16, the implant of any one or any combination of Examples 1-15 is optionally configured such that the articulation surface further comprises a convex ridge surface extending between the medial and lateral dished surface portions, the convex ridge surface defining a proximal-most point halfway between the medial dished surface portion midpoint and the lateral dished surface portion midpoint. 
     In Example 17, the implant of any one or any combination of Examples 1-16 is optionally configured such that the tibial component includes a plate component, including the tibial-contacting surface, and a bearing component, including the articulation surface. 
     In Example 18, a method comprises implanting a femoral component, of a prosthetic knee implant, having a femur-contacting surface and an opposing articulation surface onto a distal end of a resected femur, including establishing artificial medial and lateral condyles of equal width and having distal-most points located laterally from respective condyle midpoints, and further establishing an artificial trochlear groove defining a distal-most sulcus point located halfway between the distal-most points of the artificial medial condyle and the distal-most point of the lateral condyle. The method includes implanting a tibial component, of the prosthetic knee implant, having a tibial-contacting surface and an opposing articulation surface onto a proximal end of a resected tibia, including establishing artificial medial and lateral dished surface portions having distal-most points on the articulation surface located laterally from respective dished surface portion midpoints. 
     In Example 19, the method of Example 18 is optionally configured such that establishing artificial medial and lateral condyles having distal-most points located laterally from the respective condyle midpoints includes lateralizing the distal-most points between 1.0 millimeter and 4.0 millimeters, relative to the condyle midpoints. 
     In Example 20, the method of any one or any combination of Examples 18 or 21 is optionally configured such that establishing the artificial trochlear groove includes lateralizing the distal-most sulcus point between 1.0 millimeter and 4.0 millimeters, relative to a position halfway between the condyle midpoints. 
     In Example 21, the method of any one or any combination of Examples 18-20 is optionally configured such that establishing the artificial medial and lateral dished surface portions having distal-most points on the articulation surface located laterally from the respective dished surface portion midpoints includes lateralizing the distal-most points between 1.0 millimeter and 4.0 millimeters, relative to the dished surface portion midpoints. 
     In Example 22, the method of any one or any combination of Examples 18-21 is optionally configured such that implanting the femoral component further includes establishing a box-like projection extending from the femur-contacting surface and located halfway between the medial condyle midpoint and the lateral condyle midpoint. 
     In Example 23, the method of any one or any combination of Examples 18-22 is optionally configured such that implanting the tibial component further includes establishing a tibial post extending from the articulation surface and located halfway between the medial dished surface portion midpoint and the lateral dished surface portion midpoint. 
     In Example 24, the method of any one or any combination of Examples 18-23 is optionally configured such that implanting the tibial component includes implanting a tibial base plate, including the tibial-contacting surface, and a bearing component, including the articulation surface. 
     These and other examples and features of the present knee implant and methods will be set forth in part in the following Detailed Description. This Overview is intended to provide non-limiting examples of the present subject matter—it is not intended to provide an exclusive or exhaustive explanation. The Detailed Description below is included to provide further information about the present knee implant and methods. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, like numerals can be used to describe similar elements throughout the several views. Like numerals having different letter suffixes can be used to represent different views or features of similar elements. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document. 
         FIGS. 1-2  illustrate knee joint structures providing suitable environments in which a prosthetic knee implant can be used, in accordance with at least one example of the present disclosure. 
         FIG. 3  illustrates a perspective view of a femoral component of a prosthetic knee implant, in accordance with at least one example of the present disclosure. 
         FIG. 4  illustrates a side view of the femoral component shown in  FIG. 3 , in accordance with at least one example of the present disclosure. 
         FIG. 5A  illustrates a cross-sectional view of the femoral component in  FIG. 4 , along line A-A. 
         FIG. 5B  illustrates a cross-sectional view of the femoral component in  FIG. 4 , along line B-B. 
         FIG. 6  illustrates a cross-sectional view of a condyle, in accordance with at least one example of the present disclosure. 
         FIG. 7A  illustrates a front view of a femoral component, in accordance with at least one example of the present disclosure. 
         FIG. 7B  illustrates a front view of the femoral component of  FIG. 7A  when the femoral component is rotated approximately 90 degrees about a medial/lateral axis, in accordance with at least one example of the present disclosure. 
         FIG. 8  illustrates a perspective view of a tibial component of a prosthetic knee implant, in accordance with at least one example of the present disclosure. 
         FIG. 9  illustrates a front view of a tibial component of a prosthetic knee implant, in accordance with at least one example of the present disclosure. 
         FIG. 10  illustrates a front view of a tibial component of a prosthetic knee implant, in accordance with at least one example of the present disclosure. 
         FIG. 11  illustrates a front view a femoral component and a tibial component of a prosthetic knee implant, in accordance with at least one example of the present disclosure. 
         FIG. 12  illustrates a method of using a prosthetic knee implant, in accordance with at least one example of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     To better understand knee joint replacement procedures, it can be helpful to understand the relationship of bones and bone cuts that can be made to orient various provisional and permanent prosthesis components within a knee joint.  FIGS. 1 and 2  illustrate several features of knee joint structures and orientations. In  FIG. 1 , a frontal view of a lower limb  2 , including a femur  4  and a tibia  6 , is shown to illustrate various lower limb axes. The femur  4  has a longitudinal anatomic axis  8  that coincides generally with its intramedullary canal. The femur  4  also has a generally longitudinal mechanical axis  10 , or load axis, running from the center of a femoral head  12  to the center of a knee joint  14 . The angle  16  extending between these two axes varies among the patient population, but is generally on the order of between 5-7 degrees, inclusive. Like the femur  4 , the tibia  6  also has a longitudinal anatomic axis coinciding generally with its intramedullary canal. The generally longitudinal mechanical axis  18  of the tibia  6  runs from the center of the knee joint  14  to the center of an ankle region  20  and is generally collinear with its anatomic axis. 
     A joint line  22 , about which the knee joint  14  flexes, is approximately parallel to a line through medial and lateral femoral condyles  24  and to a tibial plateau  26 . Although illustrated as perpendicular in  FIG. 1 , the joint line  22  can extend at a varus or valgus angle relative to the mechanical axes  10  and  18  of the femur  4  and tibia  6 , respectively. During a partial or total knee replacement procedure, portions of a distal end of the femur  4  or a proximal end of the tibia  6  can be resected to be parallel or approximately parallel to the joint line  22 , and thus perpendicular to the mechanical axes  10  and  18 , as indicated at  28  and  30 , respectively. 
       FIG. 2  illustrates a closer view of the knee joint  14  and its coordinate system, in which a medial/lateral axis  32  corresponds approximately to the joint line  22  (illustrated in  FIG. 1 ), a proximal/distal axis  34  corresponds approximately to the mechanical axes  10  and  18  (illustrated in  FIG. 1 ), and an anterior/posterior axis  36  is approximately normal to the other two axes. Position along each of these axes can be depicted by arrows, which can represent the medial/lateral  38 , anterior/posterior  40 , and proximal/distal  42  positioning of inserted prosthesis components. Rotation about each of these axes can also be depicted by arrows. Rotation about the proximal/distal axis  34  can correspond anatomically to external rotation of a femoral component, while rotation about the anterior/posterior axis  36  and medial/lateral axis  32  can correspond to varus/valgus angle and extension plane slope of a component, respectively. Depending on a position of the proximal tibial cut  30  (illustrated in  FIG. 1 ) made, a varus/valgus angle  46 , extension plane angle  48 , external rotation  50 , or joint extension or flexion gap can be affected. Similarly, a position of the distal femoral cut  28  (illustrated in  FIG. 1 ) can affect the location of the joint line  22 , the extension gap, the varus/valgus angle  46 , or the extension plane angle  48 . 
       FIG. 3  illustrates a perspective view of a femoral component  52 , in accordance with at least one example of the present disclosure. The femoral component  52  can include a femur-contacting surface  54  formed along the inner periphery of the femoral component  52 . The femur-contacting surface  54  can be configured to contact a distal end of a femur. An opposing articulation surface  56  can be disposed opposite of the femur-contacting surface  54 . The articulation surface  56  can include a lateral condyle  66  and a medial condyle  68 . The lateral condyle  66  and the medial condyle  68  can be configured for articulation with a natural tibia or with a prosthetic tibial component. The femoral component  52  can include a proximal portion  58 , a distal portion  60 , an anterior portion  62 , and a posterior portion  64 . 
     The femoral component  52  can include an anterior flange  70 . The anterior flange  70  can have a trochlear groove  72  that is proximate the anterior portion  60 . The trochlear groove  72  can extend from a generally anterior and proximal starting point to a generally posterior and distal terminus. The trochlear groove  72  can form an anterior articular surface of the femoral component  52  for articulation with a natural or prosthetic patella. An example of a prosthetic patella that can be used with the femoral component  52  is described in U.S. Patent Publication 2012/0179264 A1, filed Dec. 6, 2011 (entitled “PROSTHETIC PATELLA”), the entire disclosure of which is hereby incorporated by reference herein. 
     In the example illustrated in  FIG. 3 , the femoral component  52  can include one or more of fixation pegs  74 , a box-like projection  78 , and a posterior cam  76  in accordance with a “posterior stabilizing” femoral component design. The one or more fixation pegs  74  and the box-like projection  78  can extend from the femur-contacting surface  54 . The fixation pegs  74  can be configured to be located within the distal end of a femur. The box-like projection  78  can be located halfway between a lateral condyle midpoint  90  and a medial condyle midpoint  91  (illustrated in  FIG. 5A ). In an example, the femoral component  52  can include two fixation pegs  74 , where each fixation peg  74  can be located adjacent or near a side of the box-like projection  78 . For example, a first fixation peg  74  can be located laterally with respect to the box-like projection  78  and a second fixation peg can be located laterally with respect to the box-like projection  78 . 
     The femoral component  52  can be modified for particular applications. For example, the posterior cam  76 , the box-like projection  78 , or both can be eliminated or modified for a particular application such as, for example, a “cruciate retaining” femoral component design that does not include at least one of the posterior cam  76  and the box-like projection  78 . 
     The femoral component  52  can define a transverse plane  80 . The transverse plane  80  can be a plane tangent to distal-most points of the lateral and medial condyles  66 ,  68 . The femoral component  52  can also define a coronal plane  82 . The coronal plane  82  can be a plane tangent to the posterior-most points of the lateral and medial condyles  66 ,  68  and, when viewed from a lateral side of the femoral component  52 , can be perpendicular to the transverse plane  80  (as illustrated in  FIG. 4 ). When the femoral component  52  is flexed or rotated approximately 90 degrees about the medial/lateral axis  32  (as illustrated in  FIG. 2 ), the posterior-most points can be positioned at the locations shown for the distal-most points and contact the transverse plane  80 . 
       FIG. 4  illustrates a side view of the femoral component  52  shown in  FIG. 1 , in accordance with at least one example of the present disclosure. The femoral component  52  can include a trochlear groove  72  that can define a patellar axis  124  (as shown in  FIGS. 7A &amp; 7B ) and a trochlear curve  84 . The patellar axis  124  and the trochlear curve  84  can be projections of a “valley line” formed along the deepest part of the valley-like concavity formed by the trochlear groove  72 . The deepest part of the valley can be referred to as the sulcus of the trochlear groove. 
     As illustrated in the example of  FIG. 4 , the lateral condyle  66  can include a distal-most point  86  and a posterior-most point  88 . The distal-most point  86  can contact the transverse plane  80  and the posterior-most point  88  can contact the coronal plane  82 . As described herein, when the femoral component  52  is flexed or rotated approximately 90 degrees about the medial/lateral axis  32 , the posterior-most point  88  can be positioned at the locations shown for the distal-most point of the femoral component  52  and can contact the transverse plan  80 . Respective distal-most ridges can extend along each of the lateral and medial condyles  66 ,  68  between the distal-most points and the posterior most-points. As the femoral component  52  is flexed or rotated a distal-most point of the lateral and medial condyles  66 ,  68  contacts the transverse plane  80 . The distal-most ridge can extend from the distal-most points of the lateral and medial condyles to the posterior-most points of the lateral and medial condyles. 
       FIG. 5A  illustrates a cross-sectional view of the femoral component  52  in  FIG. 4 , along line  5 A- 5 A. As illustrated in the example of  FIG. 5A , the lateral condyle  66  can define a lateral condyle distal-most point  86  and the medial condyle  68  can define a medial condyle distal-most point  87 . The lateral condyle  66  can have a width  92  and the lateral condyle  68  can have a width  94 . In an example, the width  92  of the lateral condyle  66  can be substantially equal to the width  94  of the lateral condyle  68 . In an example, the lateral and medial condyles  66 ,  68  of the femoral component  52  can include two vertical surfaces, an innermost and outermost surface, that can define a condyle width. For example, the widths  92 ,  94  of the lateral and medial condyles  66 ,  68  can be measured from a condyle lateral side  98  to a condyle lateral side  100 . In an example, the widths  92 ,  94  of the lateral and medial condyles  66 ,  68  can be within a range of from about 19 millimeters to about 31 millimeters, inclusive. Other widths of the lateral and medial condyles  66 ,  68  can be used and can be based on one or more factors, such as for example, the specific anatomy of a patient. 
     The widths  92 ,  94  of the lateral and medial condyles  66 ,  68  can define respective condyle midpoints. For example, the lateral condyle  66  can define a lateral condyle midpoint  90  and the medial condyle  68  can define a medial condyle midpoint  91 . The lateral and medial condyle midpoints  90 ,  91  can be located halfway between the condyle lateral side  98  and the condyle medial side  100  of the lateral and medial condyles  66 ,  68 . The distal-most points  86 ,  87  can be located laterally from the midpoints  90 ,  91 , respectively. For example, the lateral condyle distal-most point  86  can be located laterally at a distance  96  from the lateral condyle midpoint  90  and the medial condyle distal-most point  87  can be located laterally at a distance  102  from the medial condyle midpoint  91 . The distance  96  can be substantially equal to the distance  102 . In an example, the distances  96  and  102  can be within a range of from about 1.0 millimeter to 4.0 millimeters, inclusive. Other distances can be used and can be based on one or more factors, such as for example, the specific anatomy of a patient. 
       FIG. 5B  illustrates a cross-sectional view of the femoral component in  FIG. 4 , along line  5 B- 5 B. The cross-sectional view illustrated in  FIG. 5B  can be substantially identical to the cross-sectional view in  FIG. 5A . In  FIG. 5B , the lateral condyle  66  and the medial condyle  68  define respective posterior-most points  88 ,  89 . For example, the lateral condyle  66  can define a lateral condyle posterior-most point  88  and the medial condyle  68  can define a medial condyle posterior-most point  89 . The lateral and medial condyle  66 ,  68  can have substantially equal widths  92 ,  94 , as measured from a condyle lateral side  98  to a condyle lateral side  100 . As described herein, the widths  92 ,  94  of the lateral and medial condyles  66 ,  68  can define respective condyle midpoints  90 ,  91 . The lateral and medial condyle midpoints  90 ,  91  can be located halfway between the condyle lateral side  98  and the condyle medial side  100  of the lateral and medial condyles  66 ,  68 , respectively. 
     The posterior-most points  88 ,  89  can be located laterally from the midpoints  90 ,  91 , respectively. For example, the lateral condyle posterior-most point  88  can be located laterally at a distance  97  from the lateral condyle midpoint  90  and the medial condyle posterior-most point  89  can be located laterally at a distance  103  from the medial condyle midpoint  91 . In an example, the distances  97  and  103  can be substantially the same. Additionally, the distances  97  and  103  can be substantially the same as the distances  96  and  102  (as illustrated in  FIG. 5A ). 
     As described herein, the posterior-most points  88 ,  89  can be the points of the femoral component  52  that contact the coronal plane  82  (as illustrated in  FIGS. 3 &amp; 4 ). The distal-most ridge can extend along the lateral condyle  66  and the medial condyle  68 . For example, the distal-most ridge of the lateral and medial condyles  66 ,  68  can extend from the lateral and medial condyle distal-most points  86 ,  87  to the lateral and medial condyle posterior-most point  88 ,  89 . The distal-most points  86 ,  87  and the posterior-most points  88 ,  89  can be located laterally a same distance from the lateral and medial condyle midpoints  90 ,  91 . Thus, when the femoral component  52  is flexed or rotated approximately 90 degrees about the medial/lateral axis  32 , the points along the distal-most ridge can contact transverse plane  80  while the femoral component  52  is flexed or rotated. 
     As illustrated in  FIGS. 5A and 5B , the lateral and medial condyles  66 ,  68  can be curved. However, the lateral and medial condyles  66 ,  68  can include other geometries. For example, the lateral and medial condyles  66 ,  68  can be curved, substantially flat, or a combination thereof. 
       FIG. 6  illustrates a cross-sectional view of a condyle  104 , in accordance with at least one example of the present disclosure. The condyle  104 , as illustrated in the example of  FIG. 6 , can include a combination of curved and flat surfaces. The condyle  104  can include curved surfaces  116 A and  116 B (collectively referred to as “curved surfaces  116 ”) and a substantially flat surface  118  located between the two curved surfaces  116 . A width  106  of the condyle  104  can be measured from a condyle medial side  120  to a condyle lateral side  122  and the midpoint  112  of the condyle  104  can be halfway between the condyle medial side  120  and the condyle lateral side  122 . 
     The curved surfaces  116  can each include a different radius of curvature. For example, curved surface  116 A can include a radius of curvature  108  and curved surface  116 B can include a radius of curvature  110 . In an example, the radius of curvature  108  can be different from the radius of curvature  110 . For example, the radius of curvature  110  can be greater than the radius of curvature  108 . 
     The substantially flat surface  118  can be located between the curved surfaces  116  and can have a distal-most point  114 . The distal-most point  114  of the substantially flat surface  118  can be defined as the mid-point of the flat surface  118 . As illustrated in the example of  FIG. 6 , the distal-most point  114  can be located at the center of the substantially flat surface  118 . The distal-most point  144  can be located laterally from the midpoint  112 . For example, the distal-most point  114  can be located a distance  115  from the midpoint  112 . In an example, the distance  115  can be within a range of from about 1.0 millimeter to 4.0 millimeters, inclusive. 
       FIG. 7A  illustrates a front view of a femoral component  52 , in accordance with at least one example of the present disclosure. The femoral component  52  can include the trochlear groove  72 . The trochlear groove  72  can define a distal-most sulcus point  126  that can be located halfway between the distal-most points  86 ,  87  of the lateral and medial condyles  66 ,  68 . As discussed herein, the deepest part of the valley-like concavity formed by the trochlear groove  72  can be referred to as the sulcus of the trochlear groove  72 . 
     The femoral component  52  can include a concave surface  130  extending between the lateral and medial condyles  66 ,  68 . The concave surface  130  can define a proximal-most point  59  that can be located halfway between the lateral condyle distal-most point  86  and the medial condyle distal-most point  87  and substantially corresponds to the distal-most sulcus point  126 . As illustrated in the example of  FIG. 7A , the distal-most sulcus point  126  can be located halfway between the distal-most points  86 ,  87  of the lateral and medial condyles  66 ,  68 . The distal-most sulcus point  126  can also be located laterally from an axis  133  extending from a midpoint  132  located between the lateral and medial condyle midpoints  90 ,  91 . The distal-most sulcus point  126  can be shifted laterally a distance  131  from the axis  133  that can be substantially equal to the distances  96 ,  102  that the lateral and medial distal-most points  86 ,  87  are shifted laterally from the lateral and medial condyle midpoints  90 ,  91 . 
     The trochlear groove  72  can also define a patellar axis  124 . The patellar axis  124 , when viewed from an anterior side of the femoral component  52 , can form an angle  128  with respect to the transverse plane  80  that contacts the distal-most points  86 ,  87  of the lateral and medial condyles  66 ,  68 . In an example, the patellar axis  124  can be oriented substantially perpendicular to the transverse plane  80  (e.g., within +/−four degrees, inclusive). That is, the angle  128  formed between the patellar axis  124  and the transverse plane  80  can be approximately 90 degrees. The patellar axis  124 , when viewed from an anterior side of the femoral component  52 , can also be oriented substantially perpendicular to a plane connecting the lateral and medial midpoints  90 ,  91 . 
     In an example, the patellar axis  124 , when viewed from an anterior side of the femoral component  52 , can extend in a laterally diverging direction from the distal-most sulcus point  126  toward the proximal portion  58 . In an example, the angle  128  formed between the transverse plane  80  and the patellar axis  124  can be an oblique angle (e.g., greater or less than 90 degrees). 
     In an example, a distance  129  between the lateral and medial condyle midpoints  90 ,  91  can be substantially equal to a distance  127  between the lateral and medial condyle distal-most points  86 ,  87 . Thus, the distances  96 ,  102  that the lateral and medial condyle distal-most points  86 ,  87  are shifted from the lateral and medial condyle mid-points  90 ,  91  can be substantially the same. 
       FIG. 7B  illustrates a front view of the femoral component  52  of  FIG. 7A  when the femoral component  52  is rotated approximately 90 degrees about a medial/lateral axis, in accordance with at least one example of the present disclosure. As illustrated in the example of  FIG. 7B , the posterior-most points  88 ,  89  of the lateral and medial condyles  66 ,  68 , when viewed from an anterior side of the femoral component  52 , can contact with the transverse plane  80 . 
     In an example, a distance  129  between the lateral and medial condyle midpoints  90 ,  91  can be substantially equal to a distance  127  between the lateral and medial condyle posterior-most points  88 ,  89 . Again, the posterior-most points  88 ,  89  can be positioned at the locations shown for the distal-most points when the femoral component  52  is rotated or flexed approximately 90 degrees about the medial/lateral axis  32 . Thus, the distances  96 ,  102  that the lateral and medial condyle distal-most points  86 ,  87  are shifted laterally from the lateral and medial condyle midpoints  90 ,  91  can be substantially the same. 
     The (1) widths  92 ,  94  of the lateral and medial condyles  66 ,  68 , the (2) distances  90 ,  102  the distal-most points  86 ,  87  are shifted laterally from the midpoints  90 ,  91 , and the (3) distance  131  (as illustrated in  FIG. 7B ) that the trochlear groove is shifted laterally from the axis  133  can vary, such as to account for natural variation among femurs of different patients. For example, such variations may arise from different bone sizes and geometries, and correspondingly different nature knee articulation characteristics, among patients of different gender, size, age, ethnicity, build, among other factors. 
     The lateral and medial condyles  66 ,  68  can define an intercondylar notch  67 , which is the space between the lateral and medial condyles  66 ,  68 . As illustrated in the example of  FIG. 7B , the intercondylar notch  67  can be centered between the lateral and medial condyles  66 ,  68  having equal widths  92 ,  94 . As described herein, having the intercondylar notch  67  located centrally between the lateral and medial condyles  66 ,  68  can enable a surgeon to make an intercondylar box cut substantially in the middle of the patient&#39;s femur, and thereby reduce the risk of fracture in a posterior-stabilized (PS) knee compared to a PS femoral component with a lateralized intercondylar notch. 
       FIG. 8  illustrates a perspective view of a tibial component  134  of a prosthetic knee implant, in accordance with at least one example of the present disclosure. The tibial component  34  can be used alone or in conjunction with the femoral component  52  to provide a prosthetic knee implant. The tibial component  134  of  FIG. 8  illustrates a bearing component  136  and a plate component  138 . A stem component  140  can be attached or integral to the plate component  138  and can be used to secure the plate component  138  to a resected tibia. The plate component  138  can include a tibial-contacting surface  142  to contact the resected tibia and an opposing superior surface to interact with the bearing component  136 . 
     The bearing component  136  can include an articulation surface  144 , to articulate with natural or prosthetic condyles of a distal femur, and an opposing inferior surface, to interact with the superior surface of the plate component  138 . The tibial component  134  can include a proximal portion  146 , a distal portion  148 , a proximate portion  151 , and an anterior portion  153 . 
     The articulation surface  144  can include a lateral dished surface portion  150  and a medial dished surface portion  152 , with a central tibial eminence located between the lateral and medial dished surface portions  150 ,  152 . As illustrated in the example of  FIG. 8 , the eminence can, for example, be a tibial post  154  in accordance with a “Posterior Stabilized” tibial component design. While the example illustrated in  FIG. 8  represents an example of a “Posterior Stabilized” bearing component, it is contemplated that other tibial bearing components can be used, for example, “Cruciate Retaining” bearing components (such as illustrated in  FIG. 10 ). 
     A posterior cruciate ligament (PCL) cutout  151  can be located at a posterior side  155  between the lateral and medial dished surface portions  150 ,  152 . The PCL cutout  151  can be sized and located to correspond with a PCL of a knee joint. The bearing component  136  can be made available in a variety of shapes and sizes such as to accommodate a variety of patient knee joints. 
     The bearing component  136  can be located atop of the plate component  138  and the superior surface of the plate component  138  can contact the inferior surface of the bearing component  136 . The bearing component  136  and the plate component  138  can be coupled to or engaged with each other. The plate component  138  can be coupled to the bearing component  136  by any of a variety of methods. In an example, either the superior surface of the plate component  138  or the inferior surface of the bearing component  136  can include one or more projections that can be received by a corresponding cavity in the corresponding superior surface of the plate component  138  or the inferior surface of the bearing component  136 . Other coupling mechanisms are possible. 
       FIG. 9  illustrates a front view of a tibial component  134  of a prosthetic knee implant, in accordance with at least one example of the present disclosure. The lateral dished surface portion  150  can define a lateral dished surface distal-most point  163  and the medial dished surface portion  152  can define a medial dished surface distal-most point  162 . The lateral dished surface portion  150  can have a width  158  and the medial dished surface portion  152  can have a width  156 . In an example, the width  158  of the lateral dished surface portion  150  can be substantially equal to the width  156  of the medial dished surface portion  152 . In an example, the lateral and medial dished surface portions  150 ,  152  can include innermost and outermost surfaces that can define a dished surface portion width. For example, the widths  156 ,  158  of the medial and lateral dished surface portions  152 ,  150  can be measured from a dished surface lateral side  170  to a dished surface medial side  168 . In an example, the widths  156 ,  158  can also be measured by measuring a midpoint located halfway between a lateral edge of the bearing component  136  and a center point of the bearing component  136 , where the center point is halfway between the medial edge and the lateral edge of the bearing component  136 . 
     The widths  158 ,  156  of the lateral and medial dished surface portions  150 ,  152  can define respective dished surface midpoints. For example, the lateral dished surface portion  150  can define a lateral dished surface portion midpoint  161  and the medial dished surface portion  152  can define a medial dished surface portion midpoint  160 . The lateral and medial dished surface portion midpoints  161 ,  160  can be located halfway between dished surface lateral sides  170  and the dished surface medial sides  168  of the lateral and medial dished surface portions  150 ,  152 . 
     The lateral and medial dished surface portion distal-most points  163 ,  162  can be located laterally from the lateral and medial dished surface portion midpoints  161 ,  160 , respectively. For example, the lateral dished surface portion distal-most point  163  can be located laterally at a distance  166  from the lateral dished surface portion midpoint  161  and the medial dished surface distal-most point  162  can be located laterally at a distance  164  from the medial dished surface portion midpoint  91 . The distance  166  can be substantially equal to the distance  164 . In an example, the distances  166  and  164  can be substantially equal to the distances  96 ,  103 , and  131  (as illustrated in  FIG. 7A ), which can be within a range of from about 1.0 millimeter to 4.0 millimeters, inclusive. Other distances can be used and can be based on various factors, such as for example, the specific anatomy of the patient. 
     As illustrated in the example of  FIG. 9 , the tibial component  134  can include a tibial post  154  extending from the articulation surface  144  of the bearing component  136 . The tibial post  154  can be located halfway between the lateral dished surface portion midpoint  161  and the medial dished surface portion midpoint  160 . For example, a midpoint  172  of the tibial post  154  can be located halfway between the lateral dished surface portion midpoint  161  and the medial dished surface portion midpoint  160 . 
       FIG. 10  illustrates a front view a tibial component  180  of a prosthetic knee implant, in accordance with at least one example of the present disclosure. The tibial component  180  illustrated in the example of  FIG. 10  can be substantially similar to the tibial component  134  illustrated in  FIG. 9 ; however, tibial component  180  need not include a tibial post. The tibial component  180  illustrated in  FIG. 10  can include a convex ridge surface  184  extending between the lateral and medial dished surface portions  150 ,  152 . For example, the tibial component  180  in  FIG. 10  can be in accordance with a “Cruciate Retaining” tibial component design. The convex ridge surface  184  can define a proximal-most point  185  that is located halfway between the lateral dished surface portion midpoint  161  and the medial dished surface portion midpoint  160 . 
     In an example, a distance  186  between the lateral and medial dished surface portion midpoints  161 ,  160  can be substantially equal to a distance  187  between the lateral and medial dished surface portion distal-most points  163 ,  162 . Thus, the distance  166  that the lateral and medial dished surface portion distal-most points  163 ,  162  are shifted laterally from the lateral and medial dished surface portion mid-points  161 ,  160  are substantially the same. 
     The lateral dished surface portion  150  and the medial dished surface portion  152  can be symmetrical, when viewed from a posterior side of the tibial component. In an example, the lateral dished surface portion  150  and the medial dished surface portion  152  can be asymmetrical, when viewed from a posterior side of the tibial component. For example, while the dished surfaces  150 ,  152  are illustrated in  FIG. 8  as having a circular shape, other geometries and configurations are possible. 
       FIG. 11  illustrates a front view a femoral component  52  and a tibial component  134  of a prosthetic knee implant, in accordance with at least one example of the present disclosure. As illustrated in  FIG. 11 , the lateral and medial condyle distal-most points  86 ,  87  can be shifted laterally distances  96 ,  102  from the lateral and medial condyle midpoints  90 ,  91 , respectively. As described herein, distance  96  can substantially equal distance  102 . Additionally, the trochlear groove  124  can be shifted laterally a distance  131  from axis  133 . Axis  133  can extend from midpoint  132 , which can be located halfway between the lateral and medial condyle midpoints  90 ,  91 . Additionally, the lateral and medial dished surface portion distal-most points  163 ,  162  can be shifted laterally distances  166 ,  164  from the lateral and medial dished surface portion midpoints  161 ,  160 . Distances  96 ,  102 ,  124 ,  166 , and  164  can be substantially equal to each other, while the widths  92 ,  94  (as shown in  FIG. 7B ) of the lateral and medial condyles  66 ,  68  can be substantially equal to each other. As described herein, the lateralized trochlear groove  124  can provide a surgeon with an amount of lateralization before the femoral component itself is shifted laterally, and the surgeon can adjust or optimize patella tracking while reducing or minimizing implant overhang. Moreover, since the intercondylar box can remain centered between the condyles of equal width, the actual bone resection for the intercondylar box can be more central on the distal end of the femur as compared to a design with a centralized trochlear groove that would have to be shifted a greater distance laterally to achieve the same lateral position of the prosthetic trochlear groove on the distal femur. 
     A set including different sized femoral components  52 , tibial components  136 , or both can be provided, such as in a kit to allow for varying levels of lateralization. Particularly, the distance that the medial and lateral condyle distal-most points are shifted laterally from the medial and lateral condyle midpoints and the distance that the trochlear groove is shifted laterally from a midpoint centrally located between the medial and lateral condyle midpoints can vary. Additionally, the distance that the medial and lateral dished surface portion distal-most points are shifted laterally from the medial and lateral dished surface portion midpoints can vary. At least one of the femoral components  52  can include the medial and lateral condyle distal-most points shifted laterally from the medial and lateral condyle midpoints and the trochlear groove shifted laterally from the midpoint between the medial and lateral condyle midpoints. At least one of the tibial components  136  can include the medial and lateral dished surface portion distal-most points shifted laterally from the medial and lateral dished surface portion midpoints. In an example, at least one tibial component  134  that has the medial and lateral dished surface portion distal-most points shifted laterally from the medial and lateral dished surface portion midpoints can also include a tibial post that is located centrally between the medial and lateral dished surface midpoints. 
       FIG. 12  illustrates a method  200  of using a prosthetic knee implant, in accordance with at least one example of the present disclosure. At  202 , a surgeon can implant a femoral component of a prosthetic knee implant onto a distal end of a resected femur. The femoral component can include a femur-contacting surface and an opposing articulation surface. In an example, implanting the femoral component further can include establishing a box-like projection extending from the femur-contacting surface and located halfway between the medial condyle midpoint and the lateral condyle midpoint. 
     At  204 , artificial medial and lateral condyles of equal width and having distal-most points located laterally from respective condyles midpoints can be established. In an example, establishing artificial medial and lateral condyles having distal-most points located laterally from the respective condyle midpoints can include lateralizing the distal-most points between 1.0 millimeter and 4.0 millimeters, inclusive, relative to the condyle midpoints. 
     As  206 , an artificial trochlear groove that defines a distal-most sulcus point located halfway between the distal-most points of the artificial medial condyle and the distal-most point of the lateral condyle can be established. In an example, establishing the artificial trochlear groove includes lateralizing the distal-most sulcus point between 1.0 millimeter and 4.0 millimeters, inclusive, relative to a position halfway between the condyle midpoints. 
     At  208 , a tibial component, of the prosthetic knee implant, having a tibial contacting surface and a tibial-contacting surface and an opposing articulation surface onto a proximal end of a resected tibia. In an example, implanting the tibial component can include establishing a tibial post extending from the articulation surface and located halfway between the medial dished surface portion midpoint and the lateral dished surface portion midpoint. Additionally, implanting the tibial component can include implanting a plate component, including the tibial-contacting surface, and a bearing component, including the articulation surface. 
     At  210 , artificial medial and lateral dished surface portions having distal-most points on the articulation surface located laterally from respective dished surface portion midpoints can be established. In an example, establishing the artificial medial and lateral dished surface portions having distal-most points on the articulation surface located laterally from the respective dished surface portion midpoints can include lateralizing the distal-most points between 1.0 millimeter and 4.0 millimeters, inclusive, relative to the dished surface portion midpoints. 
     onto a distal end of a resected femur, including establishing artificial medial and lateral condyles of equal width and having distal-most points located laterally from respective condyle midpoints, and further establishing an artificial trochlear groove defining a distal-most sulcus point located halfway between the distal-most points of the artificial medial condyle and the artificial lateral condyle; and 
     The above Detailed Description includes references to the accompanying drawings, which form a part of the Detailed Description. The drawings show, by way of illustration, specific embodiments in which the present tibial prosthesis systems, kits, and methods can be practiced. These embodiments are also referred to herein as “examples.” While certain examples are shown and described with respect to a left knee or a right knee, it is to be appreciated that the present disclosure is equally applicable to both the left and right knees. All examples can also be used in partial or total knee replacement procedures. 
     The above Detailed Description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more elements thereof) can be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. Also, various features or elements can be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter can lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. 
     In the event of inconsistent usages between this document and any document so incorporated by reference, the usage in this document controls. 
     In this document, the terms “a” or “an” are used to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, “anterior” refers to a direction generally toward the front of a patient, “posterior” refers to a direction generally toward the back of the patient, “medial” refers to a direction generally toward the middle of the patient, and “lateral” refers to a direction generally toward the side of the patient. In this document, the phrase “anterior/posterior direction” is used to include an anterior to posterior direction or a posterior to anterior direction. 
     In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” The terms “including” and “comprising” are open-ended, that is, a system, kit, or method that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Additionally, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. 
     The Abstract is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.