Constrained knee arthroplasty

Abstract

To provide a constrained prosthetic knee.SOLUTION: A system includes a prosthesis assembly for a constrained knee including a tibial baseplate, a mobile bearing, and a fixed bearing. The tibial baseplate can include a distal surface and a proximal surface that can be configured to receive a hinge post. The mobile bearing can be configured to couple with the tibial baseplate and to rotate about at least a first axis approximated by a centerline of the hinge post. The rotation about at least the first axis can be limited by at least the first engagement feature. The fixed bearing can be configured to be coupled to the tibial baseplate. The fixed bearing can be restrained from rotating about the first axis by at least the first engagement feature of the tibial baseplate. The tibial baseplate can be configured to be assembled with either the mobile bearing or the fixed bearing.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] Claiming priority This application claims the benefit of U.S. Provisional Patent Application No. 63 / 434,590, filed December 22, 2022, and U.S. Provisional Patent Application No. 18 / 526,737, filed December 1, 2023, the benefit of priority of which is hereby claimed and incorporated by reference in its entirety.

[0002] The present subject matter relates generally to orthopedic prostheses. More specifically, the present disclosure relates to orthopedic prostheses used in constrained knee arthroplasty. [Background technology]

[0003] Orthopedic surgery and prostheses are commonly used to repair or replace damaged bones and tissues in the human body. In general, the knee is formed by a pair of condyles on the distal portion of the femur, the inferior surface of which rests against a correspondingly shaped proximal surface plateau of the tibia. The femur and tibia are connected by ligaments such as the posterior cruciate ligament, the lateral collateral ligament, the medial collateral ligament, and the anterior cruciate ligament. These ligaments provide stability to the knee joint.

[0004] A knee prosthesis can be considered either constrained or unconstrained. A constrained knee prosthesis can include femoral and tibial prostheses that are mechanically coupled or constrained to one another to limit relative movement between the femoral and tibial prostheses. Common mechanisms for such mechanical coupling can include hinges, bands, or other linkage structures. An unconstrained knee prosthesis includes femoral and tibial prostheses that are not mechanically coupled. An unconstrained knee utilizes the patient's remaining ligaments and other soft tissues to provide stability to the joint. A constrained knee prosthesis is particularly useful in cases where a patient has experienced ligament loss and / or the remaining ligaments do not provide adequate support and stability to the knee. Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure relates generally to improved constrained knee prostheses, particularly those utilizing hinge posts. Some constrained knee prostheses with hinge posts utilize a design in which the femoral component (and hinge post) is free to move proximally / distally relative to the tibial baseplate and tibial bearing components. The inventors of the present disclosure have recognized a need for a system that provides a prosthesis that is reconfigurable for either a mobile bearing system or a fixed bearing system. The system can include components that can be assembled to form a mobile bearing constrained knee prosthesis and a fixed constrained knee prosthesis.

[0006] Various embodiments are illustrated by way of example in the accompanying drawing figures, which are intended to be illustrative and not exhaustive or exclusive embodiments of the present subject matter. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 illustrates a knee joint structure that provides a suitable environment in which a constrained prosthesis assembly can be utilized, according to one embodiment of the present application. [Diagram 2] FIG. 2 illustrates a knee joint structure that provides a suitable environment in which a constrained prosthesis assembly can be utilized, according to one embodiment of the present application. [Diagram 3] FIG. 3 is a perspective view of a constrained knee prosthesis assembly according to one embodiment of the present application. [Figure 4] FIG. 4 is an exploded view of the constrained knee prosthesis assembly of FIG. 3 according to one embodiment of the present application. [Diagram 5] FIG. 5 is a top view of an example of a constrained knee prosthesis according to one embodiment of the present application. [Figure 6] FIG. 6 is a partial cross-sectional view of a constrained knee prosthesis assembly taken along marker 7-7 of FIG. 5 according to one embodiment of the present application. [Figure 7] FIG. 7 illustrates a top view of an example of a constrained knee prosthesis including a mobile bearing rotated to a first set limit in accordance with an embodiment of the present application. [Figure 8] FIG. 8 illustrates a top view of an example of a constrained knee prosthesis including a mobile bearing rotated to a second set limit in accordance with an embodiment of the present application. [Figure 9] FIG. 9 is a top view of an example of a constrained knee prosthesis including a fixed bearing, according to one embodiment of the present application. [Figure 10] FIG. 10 is a top view of an example of a constrained knee prosthesis assembly including a mobile bearing with a press insert, according to one embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present application relates to a system including a constrained knee prosthesis. The system may include a set of components, such as, for example, a tibial tray or base plate, a shackle, a femoral component, a hinge post, a poly box, and an axial bushing. The set of components may be configured to match a tibial bearing component. In embodiments, the system may include a mobile tibial bearing component or a fixed tibial bearing component, which may be interchangeable at the surgeon's discretion. The mobile tibial bearing component may be configured to limit rotation (or movement) about at least one axis when compared to the mobile tibial bearing component by engaging with one or more engagement features of the tibial tray. The fixed bearing component may prevent or significantly limit rotation (or movement) about at least one axis by contacting one or more engagement features of the tibial tray.

[0009] In another embodiment, the system may include a component set, a mobile tibial bearing component, and a press-fit insert. In such an embodiment, the press-fit insert may be configured to fill a space between the mobile tibial bearing component and one or more engagement features of the tibial tray to further limit or prevent rotation or movement of the tibial bearing component relative to the tibial bearing tray about one or more axes.

[0010] To better understand knee replacement surgery, it may be useful to understand the relationship between bone cuts and bones that can be made for the purpose of orienting various provisional and permanent prosthetic components within the knee joint. Figures 1 and 2 illustrate some features and orientations of the knee joint structure. In Figure 1, a front view of a leg 102 including a femur 104 and a tibia 106 illustrates various legs axes. The femur 104 has an anatomical axis 108 that generally coincides with its intramedullary canal. The femur 104 also has a mechanical axis 110 or load axis that runs from the center of the femoral head 112 to the center of the knee joint 114. The angle 116 extending between these two axes varies between patient populations, but is generally between 5 degrees and 7 degrees. Similar to the femur 104, the tibia 106 also has an anatomical axis that generally coincides with its intramedullary canal. The mechanical axis 118 of the tibia 106 runs from the center of the knee joint 114 to the center of the talocrural segment 120 and is generally collinear with its anatomical axis.

[0011] A joint line 122, about which the knee joint 114 flexes, is approximately parallel to a line through the medial and lateral femoral condyles 124 and to the tibial plateau 126. Although illustrated in Figure 1 as being at a right angle, the joint line 122 can extend at a varus or valgus angle relative to the mechanical axes 110 and 118 of the femur 104 and tibia 106, respectively. Typically, during partial or total arthroplasty, portions of the distal end of the femur 104 or the proximal end of the tibia 106 are resected parallel or nearly parallel to the joint line 122 and therefore perpendicular to the mechanical axes 110 and 118, as indicated at 128 and 130, respectively.

[0012] A typical knee can move between an extension state, in which the longitudinal axes of the femur 104 and the tibia 106 are essentially parallel, and a flexion state, in which the longitudinal axes of the femur 104 and the tibia 106 form an angle of approximately 140 degrees relative to one another. In embodiments, the extension state can be limited to + / - 10 degrees, and the flexion state can be much less than 140 degrees. For example, the flexion state can include limits in which the longitudinal axes of the femur 104 and the tibia 106 form an angle of approximately 90 degrees to 140 degrees relative to one another.

[0013] 2 illustrates a closer view of the knee joint 114 and its coordinate system, where the medial / lateral axis 202 corresponds approximately to the joint line 122 (see FIG. 1), the proximal / distal axis 204 corresponds approximately to the mechanical axes 110 and 118 (see FIG. 1), and the anterior / posterior axis 206 is approximately perpendicular to the other two axes. Arrows may represent positions along each of these axes, representing the medial / lateral 208, anterior / posterior 210, and proximal / distal 212 orientation of the inserted prosthetic components. Rotation about each of these axes may be represented by arrows as well. Rotation about the proximal / distal axis 204 may correspond to the external rotation of the anatomical femoral component, while rotation about the anterior / posterior axis 206 and medial / lateral axis 202 may correspond to the extension plane slope and varus / valgus angle of the component, respectively. Depending on the location of the proximal tibial cut 130 (see FIG. 1) made, the varus / valgus angle 214, extension plane angle 216, external rotation 218, or joint extension gap can be affected. Similarly, the location of the distal femoral cut 128 (see FIG. 1) can affect the location of the joint line 122, the extension gap, varus / valgus angle 214, or extension plane angle 216.

[0014] The terms "proximal" and "distal" as used herein should be given their commonly understood anatomical interpretation. The term "proximal" generally means a direction toward the patient's torso, and the term "distal" means a direction opposite to proximal, i.e., away from the patient's torso. It should be understood that the terms "proximal" and "distal" should be interpreted as if the patient were standing with the knee joint extended. The intent is to distinguish the terms "proximal" and "distal" from the terms "anterior" and "posterior". The terms "anterior" and "posterior" as used herein should be given their commonly understood anatomical interpretation. Thus, "posterior" means the posterior of the patient, e.g., the back of the knee. Similarly, "anterior" means the front of the patient, e.g., the front of the knee. Thus, "posterior" means the opposite direction of "anterior". Similarly, the term "medial" means the opposite direction of "lateral". The term "medial / lateral" means from medial to lateral or lateral to medial. The term "proximal / distal" means proximal to distal or distal to proximal. The term "anterior / posterior" means anterior to posterior or posterior to anterior.

[0015] As used herein, the "periphery" of a tibial baseplate means any periphery when viewed in a top view, e.g., generally in a lateral anatomical plane. Alternatively, the periphery of the tibial baseplate can be any periphery when viewed in a bottom view, e.g., generally in a transverse plane, with the distal surface adapted to contact the resected proximal surface of the tibia.

[0016] The term "micromotion" refers to small movements that may exist between prosthetic components, such as between a tibial baseplate and a capture element, respectively, when a force is applied. Such small movements may occur as a result of material deformation in one or both of the interacting components, or may be the result of slight spaces or clearances between them. Micromotion is distinguished from larger movements of components, such as the proximal / distal movements of the femoral component relative to the tibial baseplate and tibial bearing components.

[0017] 3 illustrates a constrained knee prosthesis assembly 300. The prosthesis assembly 300 can include a tibial baseplate 302, a tibial bearing component 304 (sometimes referred to as a meniscal component, poly, articular component or bearing), a femoral component 306, and a hinge post 308.

[0018] The tibial bearing component 304 may be coupled to and positioned on a proximal surface 310 of the tibial baseplate 302. The tibial bearing component 304 may be formed of a polymeric material, such as ultra-high molecular weight polyethylene ("UHMWPE"). The tibial bearing component 304 may be configured to articulate with the femoral component 306 through flexion and extension of the knee joint, as is known in the art. The prosthetic assembly 300 has a femoral component 306 and a tibial baseplate 302 that are mechanically coupled to one another. This is accomplished by a hinge post 308 and other components, which are further illustrated and discussed in FIG. 4. The hinge post 308 is coupled to the femoral component 306 and is received within a recess 309 of the tibial bearing component 304 and a recess 322 of the tibial baseplate 302 (see FIG. 4).

[0019] FIG. 4 shows an exploded view of the prosthesis assembly 300, tibial baseplate 302, tibial bearing component 304, femoral component 306, hinge post 308, and further illustrates the hinge axle 312, poly box 314, axle bushing 316, shackle 318, and bushing.

[0020] The hinge post 308 is coupled to the femoral component 306 via a shackle 318, an axle bushing 316, and a hinge axle 312. A distal portion of the shackle 318 is received within a recess 309 in the tibial bearing component 304, and a distal portion is threaded or otherwise coupled to the hinge post 308. The hinge post 308 extends distally through the recess 309 of the tibial bearing component 304 and is received within a recess 322 of the tibial baseplate 302. The recess 322 of the tibial baseplate 302 that receives the hinge post 308 may be formed at least in part by a keel 324 of the tibial baseplate 302. The hinge post 308 is movable, e.g., rotatable or extendable, relative to the tibial bearing component 304 or the tibial baseplate 302. The hinge post 308 may be rotatably coupled to the femoral component 306 via the hinge axis 312. Thus, a longitudinal axis LA defining a centerline of the hinge post 308 may define a rotation / articulation axis ARA for the knee joint when the femoral component 306 and the tibial baseplate 302 are mechanically coupled.

[0021] When assembled, the shackle 318 can be placed between opposing walls of the poly box 314. When assembled onto the hinge axle 312, the axle bushing 316 also sits within an opening on the proximal portion of the shackle 318. The shackle 318 and hinge post 308 can be made of a suitable material, such as a titanium alloy, a cobalt-chromium alloy, while the axle bushing 316 and poly box 314 can be made of a different material, such as a plastic, such as UHMWPE. The axle bushing 316 can function as a bearing between the shackle 318 and the hinge axle 312. The poly box 314 can function as a bearing between the femoral component 306 and the shackle 318.

[0022] The prosthesis assembly 300 of FIG. 4 illustrates a system 326 of components in which knee extension is not limited by capture elements or other features of the prosthesis assembly 300. Thus, the system 326 provides components that are configured for full extension when assembled. Thus, as previously discussed, it relies on the soft tissue of the knee to limit extension between the femoral component 306 and the tibial baseplate 302 and tibial bearing component 304. The bushing 320 can be configured to be inserted into at least the recess 322 of the tibial baseplate 302. The bushing 320 can also be inserted into or through the recess 309 (see FIG. 3) of the tibial bearing component 304 in some embodiments. The bushing 320 can be configured to receive at least a portion of the hinge post 308. The bushing 320 can function as a bearing between the hinge post 308 and the tibial baseplate 302. The hinge post 308 may be generally proximally / distally movable relative to the bushing 320 .

[0023] 5 is a top view of an example of a mobile-bearing prosthesis, such as prosthesis assembly 500, in accordance with an embodiment of the present application. Prosthesis assembly 500 can be configured for implantation in a patient with a constrained knee. In an embodiment, prosthesis assembly 500 can include a tibial baseplate 502, a tibial insert or bearing component (tibial bearing component 504), and a hinge post 508.

[0024] The tibial baseplate 502, similar to the tibial baseplate 302 of FIG. 3, can be configured to be inserted into a tibia, such as the patient's tibia 106 of FIG. 1. The tibial baseplate 502 can include a distal surface 530 (shown in FIG. 6) and a proximal surface 532. The proximal surface 532 can be opposite the distal surface 530, and a periphery 534 of the tibial baseplate 502 can extend between the distal surface 530 and the proximal surface 532. The proximal surface 532 can include a recess configured to receive the hinge post 508. The proximal surface 532 can also include a first engagement feature 540 and a second engagement feature 550.

[0025] The tibial bearing component 504, similar to the tibial bearing component 304 of FIG. 3, can be coupled to the tibial baseplate 502 and configured to rotate about at least a first axis 542, such as, for example, external rotation 218 about the distal axis 204 of FIG. 2. In an embodiment, the first axis 542 can extend through a centerline of the hinge post 508. The tibial bearing component 504 can include a third engagement feature 560 and a fourth engagement feature 570.

[0026] The first engagement feature 540 may be configured to limit rotation or movement of the tibial bearing component 504 relative to the tibial baseplate 502 about at least the first axis 542. The first engagement feature 540 includes a protrusion 541. The protrusion 541 may extend from the proximal surface 532 of the tibial baseplate 502. Alternatively, other embodiments of the present application contemplate that the first engagement feature 540 may be a slot, aperture, or other recess. In the embodiment shown in FIG. 5, the protrusion 541 may extend from an anterior portion of the proximal surface 532 adjacent the periphery 534 and may extend away from the distal surface 530. In another embodiment, the protrusion 541 may extend from a posterior portion, medial portion, lateral portion, or any other portion of the proximal surface 532 that may limit rotation or movement of the tibial bearing component 504 relative to the tibial baseplate 502 about at least the first axis 542. The first engagement feature 540 may include a first edge 544 , a second edge 546 , and a third edge 548 .

[0027] The first edge 544 can extend posteriorly from the periphery of the tibial baseplate 502. The second edge 546 can similarly extend posteriorly from the periphery of the tibial baseplate 502. The third edge 548 can extend from the first edge 544 to the second edge 546. The third edge 548 can also include a concave shape 549 such that the thickness of the first engagement feature 540 is reduced at an intermediate portion compared to the first edge 544 or the second edge 546. In embodiments, the first edge 544 or the second edge 546 can engage the tibial bearing component 504 to limit further rotation of the tibial bearing component 504 relative to the tibial baseplate 502 about the first axis 542. The interaction between the tibial bearing component 504 and the first edge 544, second edge 546 and third edge 548 of the first engagement feature 540 is discussed in more detail below with reference to Figures 7 and 8.

[0028] The third engagement feature 560 may be configured to engage with the first engagement feature 540 of the tibial bearing component 504 to limit rotation of the tibial bearing component 504 relative to the tibial baseplate 502 about at least the first axis 542. The third engagement feature 560 may be an anterior recess that may include a first interior wall 562 and a second interior wall 564. For example, the third engagement feature 560 may be configured to contact the third edge 548 of the first engagement feature 540 when the tibial bearing component 504 is coupled to the tibial baseplate 502. Contact between the third engagement feature 560 and the third edge 548 may help retain the tibial bearing component 504 on the tibial baseplate 502.

[0029] The second inner wall 564 of the third engagement feature 560 can engage with the first edge 544. The first inner wall 562 of the third engagement feature 560 can engage with the second edge 546. Thus, the first inner wall 562 and the second inner wall 564 of the third engagement feature 560 can engage with the second edge 546 and the first edge 544, respectively, to limit rotation of the tibial bearing component 504 in either a clockwise or counterclockwise direction relative to the tibial baseplate 502 about the first axis 542. As shown in FIG. 5, the third engagement feature 560 can be formed on an anterior portion of the tibial bearing component 504 adjacent its periphery 534. In another embodiment, the third engagement feature 560 can be formed in any other portion of the tibial bearing component 504 such that the third engagement feature 560 can limit rotation of the tibial bearing component 504 relative to the tibial baseplate 502 about the first axis 542. The interaction between the third engagement feature 560 and the first engagement feature 540 is discussed in more detail below with reference to Figures 7 and 8.

[0030] The second engagement feature 550 may be configured to limit movement of the tibial bearing component 504 relative to the tibial baseplate 502 at least along the second direction 552. Movement of the tibial bearing component 504 along the second direction 552 may be limited by engagement of the second engagement feature 550 with the tibial bearing component 504. As shown in FIG. 5, the second engagement feature 550 may include a protrusion 551 extending from a central portion of the proximal surface 532, for example, adjacent to but spaced just posterior to the recess that receives the hinge post 508. In another example, the second engagement feature 550 may extend from a posterior, medial, lateral, or any other portion of the proximal surface 532, such as from a posterior, medial, lateral, or any other portion of the proximal surface 532, such that the second engagement feature 550 may limit movement of the tibial bearing component 504 relative to the tibial baseplate 502 along the second direction 552. The interaction between the tibial bearing component 504 and the second engagement feature 550 is discussed in further detail below in conjunction with FIGS.

[0031] The fourth engagement feature 570 may be configured to engage with the second engagement feature 550 of the tibial bearing component 504 to limit movement of the tibial bearing component 504 relative to the tibial baseplate 502 along at least the second direction 552. The fourth engagement feature 570 may be a wall of a recess formed in the tibial bearing component 504. The recess may be centrally located and communicable to receive the hinge post 508 in addition to the second engagement feature 550. The interaction between the fourth engagement feature 570 and the second engagement feature 550 is discussed in more detail below with reference to FIGS. 10 and 8.

[0032] 5, the first engagement feature 540 and the second engagement feature 550 of the tibial baseplate 502 can be protrusions, and the third engagement feature 560 and the fourth engagement feature 570 of the tibial bearing component 504 can be walls of a recess. In another example, the first engagement feature 540 and the second engagement feature 550 of the tibial baseplate 502 can be a recess, a ridge, a groove, or any other formation formed in a surface of the tibial baseplate 502, and the third engagement feature 560 and the fourth engagement feature 570 can be a protrusion, a ridge, an extension, or any other formation extending from a surface of the tibial bearing component 504.

[0033] 6 is a partial cross-sectional view of a constrained knee prosthesis assembly, such as the prosthesis assembly 500, taken along marker 7-7 of FIG. 5, in accordance with one embodiment of the present application. As discussed above and shown in FIG. 6, the tibial bearing component 504 may be configured to be coupled to the tibial baseplate 502. When the tibial bearing component 504 is coupled to the tibial baseplate 502, the third engagement feature 560 and the fourth engagement feature 570 of the tibial bearing component 504 may engage with the first engagement feature 540 and the second engagement feature 550, respectively.

[0034] 6, the third engagement feature 560 may include a ridge that may be slid under a surface of the protrusion 541 that faces the distal surface 530 of the tibial baseplate 502. The fourth engagement feature 570 may similarly include a ridge that may be slid under a surface of the protrusion 551 that faces the distal surface 530 of the tibial baseplate 502. Thus, during coupling of the tibial bearing component 504 to the tibial baseplate 502, the ridge of the third engagement feature 560 may be slid under the protrusion 541 and then the ridge of the fourth engagement feature 570 may be slid under the protrusion 551. During coupling, the first engagement feature 540 and the second engagement feature 550 may be configured to bend away from and toward the hinge post 508, respectively, to more easily couple the tibial bearing component 504 to the tibial baseplate 502. Once coupled, the protrusions 541 and 551 can engage with the protuberances of the third engagement mechanism 560 and the fourth engagement mechanism 570, respectively, to prevent the tibial bearing component 504 from moving in the second direction 552 relative to the tibial base plate 502.

[0035] 7 is a top view of an example of a constrained knee prosthesis, such as prosthesis assembly 500, including a mobile bearing 704 rotated to a first set limit, according to an embodiment of the present application. Similar to the tibial bearing component 504 (see FIG. 5), the mobile bearing 704 may be configured to mate with the tibial baseplate 502. As described above, the mobile bearing 704 may be aligned with the centerline of the hinge post 508 and is rotatable about at least a first axis 542. As shown in FIG. 7, the mobile bearing 704 can rotate in a direction 772.

[0036] In the direction 772, the mobile bearing 704 can rotate counterclockwise relative to the tibial baseplate 502 about the first axis 542. For example, the mobile bearing 704 can rotate counterclockwise relative to the tibial baseplate 502 about the first axis 542 until the second interior wall 564 of the third engagement feature 560 contacts the first edge 544 of the first engagement feature 540. In such an example, the contact between the second interior wall 564 and the first edge 544 can prevent the mobile bearing 704 from further rotating about the first axis 542 relative to the tibial baseplate 502. As shown in FIG. 7 , the second engagement feature 550 can engage the fourth engagement feature 570 and prevent the mobile bearing 704 from further rotating about the first axis 542 relative to the tibial baseplate 502.

[0037] 8 is a top view of an example of a constrained knee prosthesis, such as prosthesis assembly 500 including a mobile bearing 704 rotated clockwise to a second set limit, in accordance with an embodiment of the present application. The mobile bearing 704 can rotate clockwise about first axis 542 relative to the tibial baseplate 502 any number of degrees between directions 772 and 774. The prosthesis assembly 500 with the mobile bearing 704 is typically biased further toward a neutral position between directions 772 and 774.

[0038] 7 , the mobile bearing 704 can rotate relative to the tibial baseplate 502 about the first axis 542. For example, the mobile bearing 704 can rotate relative to the tibial baseplate 502 about the first axis 542 until the first interior wall 562 of the third engagement feature 560 contacts the second edge 546 of the first engagement feature 540. In such an example, the contact between the first interior wall 562 and the second edge 546 can prevent the mobile bearing 704 from further rotating relative to the tibial baseplate 502 about the first axis 542.

[0039] 9 is a top view of an example of a constrained knee prosthesis, such as prosthesis assembly 500, including a fixed bearing 904, according to an embodiment of the present application. The fixed bearing 904, such as the tibial bearing component 504 (see FIG. 5), may be configured to couple with a tibial baseplate 502. As discussed above, the fixed bearing 904 may prevent rotation or movement of the fixed bearing 904 relative to the tibial baseplate 502 about the first axis 542 and in the second direction 552.

[0040] The third engagement feature 560 of the fixed bearing 904 is configured to surround and contact the first engagement feature 540 of the tibial baseplate 502 to prevent movement of the fixed bearing 904 relative to the tibial baseplate 502 about the first axis 542. For example, the recess of the third engagement feature 560, including the first inner wall 562 and the second inner wall 564, along the anterior portion of the fixed bearing 904 is smaller than the recess of the third engagement feature 560 on the mobile bearing 704. As such, the first inner wall 562 and the second inner wall 564 of the third engagement feature 560 of the fixed bearing 904 are configured to contact the second edge 546 and the first edge 544, respectively, when the fixed bearing 904 is coupled to the tibial baseplate 502. As such, the first inner wall 562 and the second inner wall 564 of the fixed bearing 904 prevent rotation of the fixed bearing 904 relative to the tibial baseplate 502 about the first axis 542.

[0041] The fourth engagement feature 570 of the fixed bearing 904 is configured to surround and contact the second engagement feature 550 of the tibial baseplate 502 to prevent movement of the fixed bearing 904 relative to the tibial baseplate 502 about the second axis. The fourth engagement feature 570 may include a flange, protrusion, tang, or rib (rib 972). The rib 972 is configured to surround opposing sides of the second engagement feature 550 and the protrusion 551 to help prevent rotation of the fixed bearing 904 relative to the tibial baseplate 502 about the first axis 542.

[0042] FIG. 10 is a top view of an example of a prosthesis assembly 500, such as a constrained knee prosthesis assembly, including a mobile bearing, such as a mobile bearing 704 having a press fit 1070, in accordance with an embodiment of the present application.

[0043] As discussed above, the prosthesis assembly 500 can be used as a mobile bearing prosthesis by coupling the mobile bearing 704 to the tibial baseplate 502. The prosthesis assembly 500 can be used as a fixed bearing prosthesis by coupling the fixed bearing 904 to the tibial baseplate 502. In another embodiment, the prosthesis assembly 500 can be made a fixed prosthesis by using a press fit 1070. In an embodiment, the press fit 1070 can be configured to be inserted into the third engagement feature 560 of the mobile bearing 704. In this embodiment, the press fit can be configured to fill the space between the first inner wall 562 of the third engagement feature 560 and the second edge 546 of the first engagement feature 540, and can also be configured to fill the gap between the second inner wall 564 of the third engagement feature 560 and the first edge 544 of the first engagement feature 540. Thus, the press fit 1070 can effectively convert the mobile bearing 704 into a fixed bearing. In this manner, the mobile bearing 704 can be coupled onto the tibial baseplate 502, and then the press fit 1070 can be placed onto the mobile bearing 704 such that the press fit engages the third engagement feature 560.

[0044] 10, the first engagement feature 540 can include a slot extending from a periphery of the mobile bearing 704. The slot can receive the press fit 1070 such that the press fit 1070 slides within the slot and surrounds the first engagement feature 540. In the embodiment of FIG. 10, the press fit 1070 is configured to fill the entire space between the first edge 544 of the first engagement feature 540 and the second interior wall 564 of the third engagement feature 560, and to fill the entire space between the second edge 546 of the first engagement feature 540 and the first interior wall 562 of the third engagement feature 560. In another embodiment, the press fit 1070 may be configured to fill any portion of the space between the first edge 544 of the first engagement feature 540 and the second inner wall 564 of the third engagement feature 560, and to fill the space between the second edge 546 of the first engagement feature 540 and the first inner wall 562 of the third engagement feature 560.

[0045] Additional Notes and Examples The following non-limiting examples detail certain aspects of the present subject matter for solving the problems and providing the benefits, among others, discussed herein.

[0046] (Example) Example 1 is a system including a constrained knee prosthesis assembly, the system including a femoral component, a shackle component extending between a first end and a second end, a hinge axis configured to secure the femoral component to the first end of the shackle component, a tibial baseplate having a distal surface, a proximal surface opposite the distal surface, and a periphery extending between the proximal surface, the tibial baseplate including a first engagement mechanism, and a hinge post extending between a first end section and a second end section, the first end section configured to be attached to the second end section of the shackle component, the second end section being at least partially secured by a recess in the tibial baseplate. a component set including a hinge post configured to be permanently received in a tibial baseplate; a mobile bearing configured to couple to a tibial baseplate and rotate about at least a first axis approximated by a centerline of the hinge post, the mobile bearing being limited in rotation about the at least first axis by at least a first engagement feature of the tibial baseplate; and a fixed bearing configured to couple to the tibial baseplate, the fixed bearing being restrained from rotating about the first axis by at least a first engagement feature of the tibial baseplate, wherein the component set is configured to be assembled with either the mobile bearing or the fixed bearing.

[0047] In Example 2, the subject matter of Example 1 includes, wherein the first engagement feature of the tibial baseplate includes a first protrusion extending from an anterior portion of the proximal surface away from the distal surface.

[0048] In Example 3, the subject matter of Example 2 includes the first protrusion including a first edge extending posteriorly from the periphery of the tibial base plate, a second edge extending posteriorly from the periphery of the tibial base plate, and a third edge extending from the first edge to the second edge and including a concave shape.

[0049] In example 4, the subject matter of example 3 includes, wherein the tibial baseplate further includes a second engagement feature.

[0050] In Example 5, the subject matter of Example 4 includes, wherein the second engagement feature includes a second protrusion extending from a central portion of the proximal surface and extending away from the distal surface.

[0051] In Example 6, the subject matter of Example 5 includes the mobile bearing comprising a third engagement mechanism configured to contact a third edge of the first engagement mechanism when the mobile bearing and the tibial base plate are coupled, and the third engagement mechanism is also configured to engage with the first edge or the second edge of the first engagement mechanism when the mobile bearing rotates around at least the first axis.

[0052] In Example 7, the subject matter of Example 6 includes the engagement of the third engagement feature with the first edge and the second edge of the first engagement feature limiting rotation of the movable bearing.

[0053] In Example 8, the subject matter of Examples 6 to 7 includes that the third engagement mechanism is formed in a front portion of the mobile bearing.

[0054] In Example 9, the subject matter of Examples 5 to 8 includes the mobile bearing comprising a fourth engagement mechanism configured to engage with the second engagement mechanism of the tibial baseplate when the mobile bearing rotates about the second axis relative to the tibial baseplate, and engagement of the fourth engagement mechanism with the second engagement mechanism limits rotation of the mobile bearing about the second axis.

[0055] In Example 10, the subject matter of Example 9 includes, wherein the fourth engagement feature is formed in the mobile bearing adjacent to a recess configured to receive the hinge post.

[0056] In Example 11, the subject matter of Example 10 includes wherein the fourth engagement feature is rearward of a recess configured to receive a hinge post.

[0057] In Example 12, the subject matter of Examples 9-11 includes where rotation of the mobile bearing about the second axis includes adduction and abduction of the prosthetic assembly.

[0058] In Example 13, the subject matter of Examples 4 to 12 includes that the fixed bearing is configured to engage with the first engagement feature of the tibial base plate when the fixed bearing and the tibial base plate are coupled together.

[0059] In Example 14, the subject matter of Example 13 includes the fixed bearing including a third engagement feature contacting the first edge, the second edge, and the third edge of the first engagement feature to prevent rotation of the mobile bearing about at least the first axis.

[0060] In Example 15, the subject matter of Examples 13 to 14 includes the fixed bearing including a fourth engagement mechanism formed in a central portion of the fixed bearing, the fourth engagement mechanism contacting the second engagement mechanism of the tibial base plate when the fixed bearing and the tibial base plate are coupled.

[0061] In Example 16, the subject matter of Example 15 includes, wherein the fourth engagement feature includes a pair of ribs that engage with the second engagement feature on opposing sides thereof.

[0062] Example 17 is a system including a constrained knee prosthesis assembly, comprising: a tibial baseplate having a distal surface and a proximal surface opposite the distal surface and configured to accommodate a hinge post, the tibial baseplate including a first engagement mechanism; a mobile bearing coupled to the tibial baseplate and configured to rotate about at least a first axis approximated by a centerline of the hinge post, the rotation about at least the first axis being limited by at least the first engagement mechanism; and a fixed bearing configured to be coupled to the tibial baseplate, the fixed bearing being prevented from rotating about the first axis by at least the first engagement mechanism of the tibial baseplate, wherein the tibial baseplate is configured to be assembled with either the mobile bearing or the fixed bearing.

[0063] In Example 18, the subject matter of Example 17 includes, wherein the first engagement feature of the tibial base plate includes a first protrusion extending away from the distal surface and extending from an anterior portion of the proximal surface.

[0064] In Example 19, the subject matter of Example 18 includes the first protrusion including a first edge extending posteriorly from a periphery of the tibial baseplate, the periphery of the tibial baseplate being defined by a distal surface and a proximal surface of the tibial baseplate, a second edge extending posteriorly from the periphery of the tibial baseplate, and a third edge extending from the first edge to the second edge and including a concave shape.

[0065] In Example 20, the subject matter of Example 19 includes, wherein the tibial baseplate further includes a second engagement feature.

[0066] In Example 21, the subject matter of Example 20 includes, wherein the second engagement feature includes a second protrusion extending from a central portion of the proximal surface and extending away from the distal surface.

[0067] In Example 22, the subject matter of Example 21 includes, wherein the mobile bearing includes a third engagement mechanism configured to contact a third edge of the first engagement mechanism when the mobile bearing and the tibial base plate are coupled, and the third engagement mechanism is also configured to engage with the first edge or the second edge of the first engagement mechanism when the mobile bearing rotates around at least the first axis.

[0068] In Example 23, the subject matter of Example 22 includes where engagement of the third engagement feature with the first edge and the second edge of the first engagement feature limits rotation of the mobile bearing.

[0069] In Example 24, the subject matter of Examples 22 to 23 includes that the third engagement mechanism is formed in a front portion of the mobile bearing.

[0070] In Example 25, the subject matter of Examples 21 to 24 includes the mobile bearing comprising a fourth engagement mechanism configured to engage with the second engagement mechanism of the tibial base plate when the mobile bearing rotates about the second axis relative to the tibial base plate, and engagement of the fourth engagement mechanism with the second engagement mechanism limits rotation of the mobile bearing about the second axis.

[0071] In Example 26, the subject matter of Example 25 includes, wherein the fourth engagement feature is formed in the mobile bearing adjacent to a recess configured to receive the hinge post.

[0072] In Example 27, the subject matter of Example 26 includes the fourth engagement feature being rearward of a recess configured to receive a hinge post.

[0073] In Example 28, the subject matter of Examples 25 to 27 includes, wherein rotating the mobile bearing about the second axis includes adduction and abduction of the prosthesis assembly.

[0074] In Example 29, the subject matter of Examples 20 to 28 includes that the fixed bearing is configured to engage with a first engagement feature of the tibial base plate when the fixed bearing and the tibial base plate are coupled together.

[0075] In Example 30, the subject matter of Example 29 includes the fixed bearing including a third engagement mechanism contacting the first edge, the second edge, and the third edge of the first engagement mechanism to prevent rotation of the mobile bearing about at least the first axis.

[0076] In Example 31, the subject matter of Examples 29 to 30 includes the fixed bearing having a fourth engagement mechanism formed in a central portion of the fixed bearing, the fourth engagement mechanism contacting the second engagement mechanism of the tibial base plate when the fixed bearing and the tibial base plate are coupled.

[0077] In Example 32, the subject matter of Example 31 includes, wherein the fourth engagement feature includes a pair of ribs that engage with the second engagement feature on opposing sides thereof.

[0078] Example 33 is an apparatus having means for implementing any of Examples 1 to 32.

[0079] Example 34 is a system for implementing any of Examples 1 to 32.

[0080] Example 35 is a method for implementing any of examples 1 to 32.

[0081] Example 36 is a system, method, or apparatus having any element of Example 1 to Example 32.

[0082] The above detailed description includes references to the accompanying drawings, which form a part of this detailed description. The drawings show, by way of illustration, specific embodiments that can be practiced. These embodiments are also referred to herein as "examples." Such examples may include elements in addition to those shown or described. However, the inventors also contemplate examples in which only those elements shown or described are included. Moreover, the inventors also contemplate examples using any combination or permutation of what has been shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof) or with respect to other examples (or one or more aspects thereof) shown or described herein.

[0083] All publications, patents, and patent documents referred to herein are incorporated herein in their entirety as if individually incorporated by reference. In the event of a conflict of usage between this specification and these documents, the usage in the incorporated references shall be deemed to supplement that of this specification.

[0084] The terms "a" or "an" are used herein, as is common in patent documents, to include one or more, regardless of any other instance or usage of either "at least one" or "one or more." In this specification, unless otherwise indicated, the term "or" is used to mean a non-exclusive or, or "A or B" is used to include "A but B," "B but not A," and "A and B." In the appended claims, the terms "including" and "in which" are used as the plain English equivalents of the terms "comprising" and "wherein," respectively. Similarly, in the following claims, the terms "including" and "comprising" are open-ended; that is, a system, device, article, or process that includes elements other than those recited after such terms in a claim is still deemed to be within the scope of the claim. Moreover, in the following claims, the terms "first," "second," and "third" are used merely as labels and are not intended to impose numerical requirements on their objects.

[0085] The term "about" as used herein means approximately, in the region of, roughly, or around. When the term "about" is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values ​​set forth. In general, the term "about" is used herein to modify a numerical value above and below the stated value by a variance of 10%. In one embodiment, the term "about" means ±10% of the numerical value of the number with which it is used. Thus, about 50% means within the range of 45% to 55%. Numerical ranges described herein by endpoints include all numbers and fractions subsumed within that range, for example 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.90, 4, 4.24, and 5. Similarly, numerical ranges recited herein by endpoints include the subranges subsumed within that range, for example, 1 to 5 includes 1 to 1.5, 1.5 to 2, 2 to 2.75, 2.75 to 3, 3 to 3.90, 3.90 to 4, 4 to 4.24, 4.24 to 5, 2 to 5, 3 to 5, 1 to 4, and 2 to 4. Similarly, it is to be understood that all numbers and fractions thereof are presumed to be modified by the term "about."

[0086] The foregoing description is intended to be illustrative, not limiting. For example, the above-described embodiments (or one or more aspects thereof) may be used in combination with each other. For example, one of ordinary skill in the art may use other embodiments upon review of the above description. The Abstract is submitted to enable the reader to quickly ascertain the contents of the technical disclosure, with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Additionally, in the above Detailed Description, various features may be grouped together to simplify the disclosure. This should not be construed as intending that any unclaimed feature of the disclosed subject matter is essential to any claim. Rather, inventive subject matter may reside 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 embodiments should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. According to aspect (1), there is provided a system including a prosthesis assembly for a constrained knee, comprising: A femoral component; a shackle component extending between a first end and a second end; a hinge axis configured to secure the femoral component to the first end of the shackle component; a tibial baseplate having a distal surface, a proximal surface opposite the distal surface, and a periphery extending between the proximal surface, the tibial baseplate including a first engagement feature; a hinge post extending between a first end section and a second end section, the first end section configured to be attached to the second end of the shackle component and the second end section configured to be at least partially received by a recess in the tibial baseplate; A component set including: a mobile bearing coupled to the tibial baseplate and configured to rotate about at least a first axis approximated by a centerline of the hinge post, the rotation about at least the first axis being limited by at least the first engagement feature of the tibial baseplate; a fixed bearing configured to couple to the tibial baseplate, the fixed bearing being restrained from rotating about the first axis by at least the first engagement feature of the tibial baseplate; A system comprising: The component set is a system configured to be assembled with either the mobile bearing or the fixed bearing. According to aspect (2), the first engagement mechanism of the tibial base plate includes a first protrusion extending from an anterior portion of the proximal surface away from the distal surface. According to aspect (3), the first protrusion is a first edge extending posteriorly from the periphery of the tibial baseplate; a second edge extending posteriorly from the peripheral edge of the tibial baseplate; a third edge extending from the first edge to the second edge and including a concave shape; and Includes. According to aspect (4), the tibial base plate further includes a second engagement mechanism. According to aspect (5), the second engagement mechanism includes a second protrusion extending from a central portion of the proximal surface and extending away from the distal surface. According to aspect (6), the mobile bearing includes a third engagement mechanism configured to contact the third edge of the first engagement mechanism when the mobile bearing and the tibial base plate are coupled, and the third engagement mechanism is also configured to engage with the first edge or the second edge of the first engagement mechanism when the mobile bearing rotates at least around the first axis. According to aspect (7), engagement of the third engagement mechanism with the first edge and the second edge of the first engagement mechanism limits the rotation of the movable bearing. According to aspect (8), the third engagement mechanism is formed in a front portion of the movable bearing. According to aspect (9), the mobile bearing includes a fourth engagement mechanism configured to engage with the second engagement mechanism of the tibial base plate when the mobile bearing rotates about a second axis relative to the tibial base plate, and engagement between the fourth engagement mechanism and the second engagement mechanism limits the rotation of the mobile bearing about the second axis. According to aspect (10), the fourth engagement mechanism is formed in the mobile bearing adjacent to a recess configured to receive the hinge post. According to aspect (11), the fourth engagement feature is rearward of the recess configured to receive the hinge post. According to aspect (12), the rotation of the mobile bearing about the second axis includes adduction and abduction of the prosthesis assembly. According to aspect (13), the fixed bearing is configured to engage with the first engagement feature of the tibial baseplate when the fixed bearing and the tibial baseplate are combined. According to aspect (14), the fixed bearing includes a third engagement mechanism that contacts the first edge, the second edge, and the third edge of the first engagement mechanism to prevent rotation of the movable bearing around at least the first axis. According to aspect (15), the fixed bearing includes a fourth engagement mechanism formed within a central portion of the fixed bearing, the fourth engagement mechanism contacting the second engagement mechanism of the tibial base plate when the fixed bearing and the tibial base plate are coupled. According to aspect (16), the fourth engagement mechanism includes a pair of ribs that engage with the second engagement mechanism on opposing sides thereof. According to an aspect (17), there is provided a system including a prosthesis assembly for a constrained knee, comprising: a tibial baseplate having a distal surface and a proximal surface opposite the distal surface and configured to receive a hinge post, the tibial baseplate including a first engagement feature; a mobile bearing coupled to the tibial baseplate and configured to rotate about at least a first axis approximated by a centerline of the hinge post, the rotation about at least the first axis being limited by at least the first engagement mechanism; a fixed bearing configured to be coupled to the tibial baseplate, the fixed bearing being restrained from rotating about the first axis by at least the first engagement feature of the tibial baseplate; A system comprising: The tibial baseplate is a system configured to be assembled with either the mobile bearing or the fixed bearing. According to an eighteenth aspect, the first engagement feature of the tibial baseplate includes a first protrusion extending from an anterior portion of the proximal surface away from the distal surface, the first protrusion comprising: a first edge extending posteriorly from a periphery of the tibial baseplate, the periphery of the tibial baseplate being defined by the distal surface and the proximal surface of the tibial baseplate; a second edge extending posteriorly from the peripheral edge of the tibial baseplate; a third edge extending from the first edge to the second edge and including a concave shape; and Includes. According to aspect (19), the tibial base plate further comprises a second engagement mechanism including a second protrusion extending from a central portion of the proximal surface and extending away from the distal surface, and the mobile bearing comprises a third engagement mechanism configured to contact the third edge of the first engagement mechanism when the mobile bearing and the tibial base plate are coupled, and the third engagement mechanism is also configured to engage with the first edge or the second edge of the first engagement mechanism when the mobile bearing rotates at least around the first axis, and engagement of the third engagement mechanism with the first edge and the second edge of the first engagement mechanism limits the rotation of the mobile bearing. According to aspect (20), the mobile bearing includes a fourth engagement mechanism configured to engage with the second engagement mechanism of the tibial base plate when the mobile bearing rotates about a second axis relative to the tibial base plate, engagement between the fourth engagement mechanism and the second engagement mechanism limits the rotation of the mobile bearing about the second axis, the fourth engagement mechanism is formed in the mobile bearing adjacent to a recess configured to accommodate the hinge post, the fourth engagement mechanism is posterior to the recess configured to accommodate the hinge post, and the rotation of the mobile bearing about the second axis includes adduction and eversion of the prosthesis assembly.

Claims

1. 1. A system including a prosthesis assembly for a constrained knee, comprising: A femoral component; a shackle component extending between a first end and a second end; a hinge axis configured to secure the femoral component to the first end of the shackle component; a tibial baseplate having a distal surface, a proximal surface opposite the distal surface, and a periphery extending between the proximal surface, the tibial baseplate including a first engagement feature; a hinge post extending between a first end section and a second end section, the first end section configured to be attached to the second end of the shackle component and the second end section configured to be at least partially received by a recess in the tibial baseplate; A component set including: a mobile bearing of a mobile tibial bearing component adapted to fit the component set and accommodate the hinge post, the mobile bearing adapted to couple with the tibial baseplate and rotate about at least a first axis approximated by a centerline of the hinge post, the rotation about at least the first axis being limited by at least the first engagement feature of the tibial baseplate; a fixed bearing of a fixed tibial bearing component adapted to fit the component set and to receive the hinge post, the fixed bearing adapted to couple to the tibial baseplate and restrained from rotating about the first axis by at least the first engagement feature of the tibial baseplate; A system comprising: The system, wherein the mobile bearing of the mobile tibial bearing component and the fixed bearing of the fixed tibial bearing component are interchangeable within the prosthetic assembly.

2. The system of claim 1 , wherein the first engagement feature of the tibial baseplate includes a first protrusion extending from an anterior portion of the proximal surface away from the distal surface.

3. The first protrusion includes: a first edge extending posteriorly from the periphery of the tibial baseplate; a second edge extending posteriorly from the peripheral edge of the tibial baseplate; a third edge extending from the first edge to the second edge and including a concave shape; and The system of claim 2 , comprising:

4. The system of claim 3 , wherein the tibial baseplate further comprises a second engagement feature.

5. The system of claim 4 , wherein the second engagement feature includes a second protrusion extending from a central portion of the proximal surface and extending away from the distal surface.

6. 6. The system of claim 5, wherein the mobile bearing comprises a third engagement mechanism configured to contact the third edge of the first engagement mechanism when the mobile bearing and the tibial base plate are coupled together, the third engagement mechanism also configured to engage the first edge or the second edge of the first engagement mechanism when the mobile bearing rotates about at least the first axis.

7. The system of claim 6 , wherein engagement of the third engagement feature with the first edge and the second edge of the first engagement feature limits rotation of the mobile bearing.

8. The system of claim 6 , wherein the third engagement mechanism is formed in a forward portion of the mobile bearing.

9. 6. The system of claim 5, wherein the mobile bearing comprises a fourth engagement mechanism configured to engage the second engagement mechanism of the tibial baseplate when the mobile bearing moves relative to the tibial baseplate along a second direction parallel to the first axis, and engagement of the fourth engagement mechanism with the second engagement mechanism limits the movement of the mobile bearing along the second direction.

10. The system of claim 9 , wherein the fourth engagement feature is formed in a mobile bearing adjacent a recess configured to receive the hinge post.

11. The system of claim 10 , wherein the fourth engagement feature is rearward of the recess configured to receive the hinge post.

12. The system described in claim 9, wherein the movement of the movable bearing along the second direction includes adduction and abduction of the prosthesis assembly.

13. The system of claim 4 , wherein the fixed bearing is configured to engage the first engagement feature of the tibial baseplate when the fixed bearing and the tibial baseplate are coupled together.

14. 14. The system of claim 13, wherein the fixed bearing comprises a third engagement mechanism that contacts the first edge, the second edge, and the third edge of the first engagement mechanism to prevent rotation of the mobile bearing about at least the first axis.

15. 14. The system of claim 13, wherein the fixed bearing includes a fourth engagement feature formed in a central portion of the fixed bearing, the fourth engagement feature contacting the second engagement feature of the tibial baseplate when the fixed bearing and the tibial baseplate are mated.

16. The system of claim 15 , wherein the fourth engagement feature includes a pair of ribs that engage on opposing sides of the second engagement feature.

17. 1. A system including a prosthesis assembly for a constrained knee, comprising: a tibial baseplate having a distal surface and a proximal surface opposite the distal surface and configured to receive a hinge post, the tibial baseplate including a first engagement feature; a mobile bearing as a mobile tibial bearing component configured to fit the tibial baseplate and receive the hinge post, the mobile bearing being configured to couple with the tibial baseplate and rotate about at least a first axis approximated by a centerline of the hinge post, the rotation about at least the first axis being limited by at least the first engagement mechanism; a fixed bearing as a fixed tibial bearing component configured to fit the tibial baseplate and receive the hinge post, the fixed bearing configured to be coupled to the tibial baseplate and restrained from rotating about the first axis by at least the first engagement feature of the tibial baseplate; A system comprising: The system, wherein the mobile bearing of the mobile tibial bearing component and the fixed bearing of the fixed tibial bearing component are interchangeable within the prosthetic assembly.

18. The first engagement feature of the tibial baseplate includes a first protrusion extending from an anterior portion of the proximal surface away from the distal surface, the first protrusion comprising: a first edge extending posteriorly from a periphery of the tibial baseplate, the periphery of the tibial baseplate being defined by the distal surface and the proximal surface of the tibial baseplate; a second edge extending posteriorly from the peripheral edge of the tibial baseplate; a third edge extending from the first edge to the second edge and including a concave shape; and The system of claim 17 , comprising:

19. 20. The system of claim 18, wherein the tibial baseplate further comprises a second engagement mechanism including a second protrusion extending from a central portion of the proximal surface and extending away from the distal surface, and the mobile bearing comprises a third engagement mechanism configured to contact the third edge of the first engagement mechanism when the mobile bearing and the tibial baseplate are coupled together, the third engagement mechanism also configured to engage the first edge or the second edge of the first engagement mechanism when the mobile bearing rotates about at least the first axis, and engagement of the third engagement mechanism with the first edge and the second edge of the first engagement mechanism limits rotation of the mobile bearing.

20. the mobile bearing includes a fourth engagement feature configured to engage the second engagement feature of the tibial baseplate when the mobile bearing moves along a second direction relative to the tibial baseplate parallel to the first axis; engagement of the fourth engagement mechanism with the second engagement mechanism limits the movement of the mobile bearing along the second direction; the fourth engagement feature is formed in the mobile bearing adjacent a recess configured to receive the hinge post; the fourth engagement feature is rearward of the recess configured to receive the hinge post; 20. The system of claim 19, wherein the movement of the mobile bearing along the second direction includes adduction and abduction of the prosthetic assembly.

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