Constrained prosthetic knee

Abstract

To provide a constrained prosthetic knee.SOLUTION: In a prosthesis assembly, a hinge post can extend through a tibial bearing component and be at least partially received in a recess of a tibial tray. A femoral component can contact an articular surface of the tibial bearing component. A shackle can be coupled to the hinge post and configured to be inserted between a medial condyle and a lateral condyle of the femoral component. Walls can be positioned between the femoral component and the shackle. A hinge axle can be configured to secure the femoral component to the shackle. A bump stop can be removably attached to the femoral component and configured to contact the shackle at a set limit of rotation of the femoral component relative to the tibial bearing component.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] Claims of Priority This application claims the benefit of U.S. Provisional Patent Application No. 63 / 434,563, filed Dec. 22, 2022, and U.S. Patent Application No. 18 / 526,693, filed Dec. 1, 2023, the benefit of priority of which is claimed herein and the entire disclosures of which are incorporated herein by reference.

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

Background Art

[0003] Orthopedic procedures and prostheses are commonly utilized to repair or replace damaged bones and tissues within the human body. Generally, the knee is formed by a condyle at the distal portion of the femur, the lower surface of which presses against a proximal surface plateau having a corresponding shape 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] Artificial knee joints can be considered either constrained or unconstrained. A constrained artificial knee system can include femur and tibia prostheses, which are mechanically linked or constrained relative to each other to limit relative movement between the femur and tibia prostheses. Common mechanisms for such mechanical linkages can include hinges, bands, or other linkage structures. An unconstrained artificial knee system includes femur and tibia prostheses that are not mechanically linked. Unconstrained knees utilize the patient's remaining ligaments and other soft tissues to provide joint stability. Constrained artificial knees are particularly useful in cases where the patient has experienced ligament loss and / or the remaining ligaments do not provide adequate support and stability to the knee.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure generally relates to an improved constrained knee prosthesis, particularly one that utilizes a hinge post. Some constrained knee prostheses with hinge posts utilize a design in which the femoral component (and hinge post) can move freely proximally / distally relative to the tibial baseplate and tibial bearing component. Such an arrangement can enable distraction of the knee joint. However, the inventor has found that in a certain layer of patients who receive a constrained knee prosthesis with a hinge post, there may not be sufficient soft tissue within the knee joint to prevent the femoral component from extending from the tibial baseplate and tibial bearing and then dislocating. Dislocation can result in pain and other complications for the patient.

Means for Solving the Problems

[0006] Due to design constraints of the improved prosthesis, components with an increased width are required to improve the strength of such components. Furthermore, the inventors of the present application have discovered that in the case of the knee prosthesis, since it relates to the tibial baseplate, there is a minimum amount of adjustment that can change the rotation of the femoral component.

[0007] In the figures of the accompanying drawings, various embodiments are shown by way of example. Such embodiments are illustrative and are not intended to be an exhaustive or exclusive embodiment of the subject matter.

Brief Description of the Drawings

[0008]

Figure 1

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Figure 3

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DETAILED DESCRIPTION OF THE INVENTION

[0009] The present application relates to a constrained knee prosthesis. The prosthesis can include a shackle having an increased width to improve the strength of the shackle. The femoral component can include a frustoconical profile to accommodate the shackle having an increased width and to fit within the same overall prosthesis envelope. The prosthesis can also include a wall configured to engage a frustoconical profile on the femoral component that at least partially surrounds the shackle and is complementary to the frustoconical profile on the femoral component.

[0010] The prosthesis can also include a bumper stop that can be removably attached to the femoral component such that when the knee joint is in an extended state, the bumper stop contacts the shackle to prevent further rotation of the femoral component relative to the tibial baseplate. The prosthesis can be configured to enable maintenance of the bumper stop. Thus, the bumper stop can be removed, for example adjusted to quickly change the rotation of the femoral component relative to the tibial baseplate without removing the bumper stop, or replaced without removing the prosthesis from the knee. For example, the prosthesis can be configured to remove, adjust, or replace the bumper stop when the knee joint is in a flexed state.

[0011] To better understand knee replacement, it may be useful to understand the relationship between the bone cut portions and the bone that can be formed for the purpose of orienting various provisional and permanent prosthesis components within the knee joint. FIGS. 1 and 2 illustrate some features and orientations of the knee joint structure. In FIG. 1, a front view of a lower limb 102 including a femur 104 and a tibia 106 illustrates various lower limb axes. The femur 104 generally has an anatomical axis 108 that coincides with its intramedullary canal. The femur 104 also has a mechanical axis 110 or load axis that extends 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 among patient populations but is generally between 5 and 7 degrees. Similar to the femur 104, the tibia 106 also generally has an anatomical axis that coincides with its intramedullary canal. The mechanical axis 118 of the tibia 106 extends from the center of the knee joint 114 to the center of the leg portion 120 and is generally collinear with its anatomical axis.

[0012] The joint line 122, which is the center about which the knee joint 114 flexes, is substantially parallel to the line passing through the medial and lateral femoral condyles 124 and the tibial plateau 126. Although illustrated as intersecting at right angles in FIG. 1, the joint line 122 can extend at a varus or valgus angle with respect to the mechanical axes 110 and 118 of the femur 104 and tibia 106, respectively. Usually, during a partial or total replacement procedure, a portion of the distal end of the femur 104 or the proximal end of the tibia 106 is resected perpendicular to the mechanical axes 110 and 118, respectively, parallel or substantially parallel to the joint line 122, and thus marked at 128 and 130, respectively.

[0013] A typical knee can move between an extended state in which the longitudinal axes of the femur 104 and tibia 106 are essentially parallel and a flexed state in which the longitudinal axes of the femur 104 and tibia 106 form an angle of about 140 degrees with respect to each other. In an embodiment, the extended state can be limited to + / - 10 degrees, and the flexed state can be much less than 140 degrees. For example, the flexed state can include a limit in which the longitudinal axes of the femur 104 and tibia 106 form an angle of about 90 degrees to 140 degrees with respect to each other.

[0014] FIG. 2 illustrates a more detailed view of the knee joint 114 and its coordinate system, where the medial / lateral axis 202 approximately corresponds to the joint line 122 (see FIG. 1), the proximal / distal axis 204 approximately corresponds to the mechanical axes 110 (see FIG. 1) and 118 (see FIG. 1), and the anterior / posterior axis 206 is approximately perpendicular to the other two axes. Arrows can depict positions along each of these axes representing the medial / lateral 208, anterior / posterior 210, and proximal / distal 212 positions of the inserted prosthetic components. Rotations about each of these axes can also be depicted by arrows. Rotation about the proximal / distal axis 204 can correspond anatomically to external rotation of the femoral component, while rotations about the anterior / posterior axis 206 and the medial / lateral axis 202 can correspond respectively to the extension plane gradient and the varus / valgus angle of the component. Depending on the position of the formed proximal tibial cut portion 130 (see FIG. 1), the varus / valgus angle 214, the extension plane angle 216, the external rotation 218, or the joint extension gap may be affected. Also, the position of the distal femoral cut portion 128 (see FIG. 1) can affect the location of the joint line 122, the extension gap, the varus / valgus angle 214, or the extension plane angle 216.

[0015] As used herein, the terms "proximal" and "distal" should be given their generally understood anatomical interpretations. The term "proximal" generally means in the direction towards the patient's torso, and the term "distal" means in the direction opposite to proximal, i.e., away from the patient's torso. The terms "proximal" and "distal" should be understood as if the patient were standing with the knee joint extended. The intent is to distinguish the terms "proximal" and "distal" from the terms "front" and "back". As used herein, the terms "front" and "back" should be given their generally understood anatomical interpretations. Thus, "back" means the posterior part of the patient, such as the back of the knee. Also, "front" means the anterior part of the patient, such as the front of the knee. Thus, "back" means the direction opposite to "front". Also, the term "lateral" means the direction opposite to "medial". The terms "medial / lateral" mean from medial to lateral or from lateral to medial. The terms "proximal / distal" mean from proximal to distal or from distal to proximal. The terms "front / back" mean from front to back or from back to front.

[0016] As used herein, the "periphery" of the tibial base plate means any periphery, for example, as seen in a top view in a generally transverse anatomical plane. Alternatively, the periphery of the tibial base plate can be any periphery as seen in a bottom view of a distal surface adapted to contact the resected proximal surface of the tibia, for example, in a generally transverse plane.

[0017] Figure 3 shows a constrained knee prosthesis assembly 300. The prosthesis assembly 300 can include a tibial base plate 302, a tibial bearing component 304 (which may also be referred to as a meniscal component, a polymer, an articular component, or a bearing), a femoral component 306, and a hinge post 308.

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

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

[0020] The hinge post 308 is connected to the femoral component 306 via a shackle 318, a shaft bushing 316, and a hinge shaft 312. The distal portion of the shackle 318 is received within a recess 309 in the tibial bearing component 304 and is threaded or otherwise connected 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 in the tibial base plate 302. The recess 322 in the tibial base plate 302 that receives the hinge post 308 can be formed, at least in part, by a keel 324 of the base plate 302. The hinge post 308 can be movable relative to the tibial bearing component 304 or the tibial base plate 302, for example, rotatable or extensible. The hinge post 308 can be rotatably connected to the femoral component 306 via the hinge shaft 312. Thus, the longitudinal axis LA that defines the centerline of the hinge post 308 can define the rotational / articulation axis ARA for the knee joint, since the femoral component 306 and the tibial base plate 302 are mechanically linked.

[0021] Upon assembly, the shackle 318 can be positioned between opposing walls of the polybox 314. When assembled onto the hinge shaft 312, the shaft bushing 316 is further positioned within an opening on the proximal portion of the shackle 318. The shackle 318 and the hinge post 308 can be formed of a suitable material such as a titanium alloy, a cobalt-chromium alloy, etc., while the shaft bushing 316 and the polybox 314 can be formed of a different material such as a plastic like UHMWPE. The shaft bushing 316 can act as a bearing between the shackle 318 and the hinge shaft 312. The polybox 314 can act as a bearing between the femoral component 306 and the shackle 318.

[0022] The prosthesis assembly 300 of FIG. 4 shows a system 326 of components where knee extension is not restricted by a capture element or other feature of the prosthesis assembly 300. Thus, system 326 provides components configured to fully extend when assembled. Thus, as discussed previously, the knee soft tissue relies on restricting the extension between the femoral component 306, the tibial baseplate 302, and the tibial bearing component 304. The bushing 320 can be configured to insert at least within the recess 322 of the tibial baseplate 302. The bushing 320 can also be inserted within or through the recess 309 (see FIG. 3) of the tibial bearing component 304 in some embodiments. The bushing 320 can be configured to accommodate at least a portion of the hinge post 308. The bushing 320 can act as a bearing between the hinge post 308 and the tibial baseplate 302. The hinge post 308 can generally be movable proximally / distally relative to the bushing 320.

[0023] FIG. 5 is a cross-sectional view of an embodiment of a constrained knee prosthesis assembly (prosthesis assembly 500) according to an embodiment of the present application. The prosthesis assembly 500 can include a tibial tray 502, a tibial bearing component 504, a femoral component 506, a hinge post 508, a shackle 518, and a hinge shaft 512.

[0024] The tibial tray 502, for example, the tibial baseplate 302 of FIGS. 3-4, can extend from a proximal surface 510, such as the proximal surface 310 of FIG. 3, to a distal surface. The proximal surface 510 and the distal surface can define a periphery therebetween. The periphery can extend between a front edge and a rear edge of the tibial tray 502. The proximal surface 510 can include a recess 522 that extends towards the distal surface. The recess 522, for example, the recess 322 of FIG. 4, can be configured to at least partially accommodate the hinge post 508.

[0025] The tibial bearing component 504, such as the tibial bearing component 304 in FIGS. 3 to 4, can engage with the tibial tray 502. For example, the tibial tray 502 can support the tibial bearing component 504 while the tibial bearing component 504 engages with the femoral component 506. In one embodiment, the tibial bearing component 504 can include an articular surface 505. The articular surface 505 can be configured to engage with the femoral component 506. More specifically, the articular surface 505 can be configured to engage with the medial and lateral condyles of the femoral component 506.

[0026] The femoral component 506, such as the femoral component 306 in FIGS. 3 to 4, can contact the articular surface 505 of the tibial bearing component 504 and can be configured to articulate with the tibial bearing component 504.

[0027] The hinge post 508, such as the hinge post 308 in FIGS. 3 to 4, can extend through the tibial bearing component 504 and can be at least partially received within the recess 522 of the tibial tray 502. The hinge post 508 can include a portion that extends inside the recess 522 of the tibial tray 502 and a portion that extends outside the recess 522 of the tibial tray 502. The portion of the hinge post 508 that extends inside the recess 522 can include threads that are complementary to the threads inside the recess 522. The portion of the hinge post 508 that extends outside the recess 522 can be received by a bushing that can include a threaded surface that is complementary to the attachment mechanism on the shackle 518, any other optional attachment mechanism, etc. The portion of the hinge post 508 that extends outside the recess 522 can be configured to extend through the femoral component 506 such that the femoral component 506 surrounds the hinge post 508 when the hinge post 508 is installed within the recess 522 of the tibial tray 502.

[0028] The shackle 518, such as the shackle 318 in FIGS. 3 and 4, is configured to couple to the hinge post 508 and can have other components of the prosthesis assembly 500 attached thereto for attaching additional components to the prosthesis assembly 500. The shackle 518 can extend between a first end 530 and a second end 532. The first end 530 can be configured to attach, couple, or mate with the hinge post 508. For example, the first end 530 can include a threaded surface that is complementary to a threaded surface on the portion of the hinge post 508 that extends outside of the recess 522. The second end 532 can be configured to receive the hinge axle 512 for attaching one or more components of the prosthesis assembly 500 to the shackle 518. For example, the second end 532 can include an opening configured to receive the hinge axle 512. The shackle 518 can be configured to be inserted into the intercondylar region 507 of the femoral component 506 .

[0029] The hinge axle 512, such as the hinge axle 312 in FIGS. 3 and 4 , can be configured to secure, among other components, the femoral component 506 to the shackle 518 and to the hinge post 508 via the shackle 518. The hinge axle 512 can be an elongated member that extends a distance greater than the thickness of the femoral component 506 such that the hinge axle 512 can be used to retain components, including the femoral component 506, on the shackle 518. For example, the hinge axle 512 can attach the femoral component 506 and the wall 514 to the shackle 518 through an opening in the shackle 518 that is configured to receive the hinge axle 512. The prosthesis assembly 500 can also include one or more bushings, washers, or any other components that can complement the interaction between the hinge axle 512 and the opening in the shackle 518.

[0030] Walls 514, such as polybox 314 of FIGS. 3-4, are discussed in more detail below with reference to FIGS.

[0031] The prosthesis assembly 500 can also include a bumper stop 528 that can be removably attached to the femur component 506. As shown in FIG. 5, when the prosthesis assembly 500 is in the extended state, the bumper stop 528 can contact the shackle 518 to prevent further rotation of the femur component 506 relative to the tibia bearing component 504. The bumper stop 528 will be discussed in detail below with reference to FIGS. 7-9.

[0032] FIG. 6 is a perspective view of an example of a femur component, such as the femur component 506, according to an embodiment of the present invention. In the example, the femur component 506 can include an intercondylar region 507 that extends between the medial and lateral condyles of the femur component 506. The femur component 506 can include an internal medial condyle wall 509 and an internal lateral condyle wall 511. The intercondylar region 507 can extend between the internal medial condyle wall 509 and the internal lateral condyle wall 511. The intercondylar region 507, the internal medial condyle wall 509, and the internal lateral condyle wall 511 can be configured to engage the shackle 518, more specifically the wall 514, during articulation of the prosthesis assembly 500.

[0033] The inner inner granule wall 509 can include a frustoconical profile 513, and the inner outer granule wall 511 can include a frustoconical profile 515. In one embodiment, the frustoconical profile 513 can extend across the entire inner inner granule wall 509. In another embodiment, the frustoconical profile 513 can extend across only a portion of the inner inner granule wall 509. In one embodiment, the frustoconical profile 515 can extend across the entire inner outer granule wall 511. In another embodiment, the frustoconical profile 515 can extend across only a portion of the inner outer granule wall 511. The frustoconical profile 513 of the inner inner granule wall 509 and the frustoconical profile 515 of the inner outer granule wall 511 can each maximize the thickness of the inner inner granule wall 509 and the inner outer granule wall 511, minimizing the space occupied by the inner inner granule wall 509 and the inner outer granule wall 511 while maximizing the strength of the inner inner granule wall 509 and the inner outer granule wall 511. Further, the frustoconical profile 513 and the frustoconical profile 515 can each be configured to reduce stress concentration within the inner inner granule wall 509 and the inner outer granule wall 511, respectively.

[0034] Figures 7 and 8 are discussed together below. Figure 7 is a perspective view of a portion of a constrained knee prosthesis, such as prosthesis assembly 500, according to one embodiment of the present application. Figure 8 is an exploded view of prosthesis assembly 500. Prosthesis assembly 500 can include two or more multi-walls or serviceable walls (wall 514). Wall 514 can be configured to at least surround a portion of shackle 518. In an embodiment, shackle 518 can be an overmold held in place across its entirety by hinge shaft 512 extending through an opening in wall 514. In another embodiment, wall 514 can fit across shackle 518 such that hinge shaft 512 holds wall 514 on shackle 518. Here, wall 514 can be attachable to shackle 518 via an opening in hinge shaft 512 and a second end 532 of shackle 518.

[0035] As shown in FIGS. 3-4 above, the polybox 314 can be an integrated design configured to partially surround the shackle 318. However, as shown in FIGS. 7 and 8, the wall 514 can also be a two-piece design configured to at least partially surround the shackle 518. Thus, the wall 514 can include a first wall 534 and a second wall 536. The two-piece design of the wall 514 is less complex than the integrated design of the polybox 314, making the wall 514 easier to manufacture. For example, the first wall 534 and the second wall 536 can be manufactured separately and assembled before or during the assembly of the prosthesis assembly 500.

[0036] The first wall 534 can be configured to cover a first wall 540 of the shackle 518. The second wall 536 can be configured to cover a second wall 542 of the shackle 518. The first wall 534 and the second wall 536 can be joined together on a front edge 544 of the shackle 518. The first wall 534 and the second wall 536 can include an attachment mechanism 519 that removably couples the first wall 534 to the second wall 536 to form the wall 514. The attachment mechanism 519 can also inhibit relative movement between the first wall 534 and the second wall 536 in one or more directions. For example, the attachment mechanism 519 can include a dovetail formation that joins the first wall 534 and the second wall 536. In another embodiment, the attachment mechanism 519 can include a solid joint that can join the first wall 534 and the second wall 536. In yet another embodiment, the attachment mechanism 519 can be any attachment mechanism that can join the first wall 534 and the second wall 536 together. For example, the attachment mechanism 519 can include tabs, slots, patterns, protrusions, grooves, or any other geometric feature that can be used to join the first wall 534 and the second wall 536.

[0037] In an embodiment, at least a portion of the first wall 534 can include a frustoconical profile 535, and at least a portion of the second wall 536 can include a frustoconical profile 537. The frustoconical profile 535 of the first wall 534 can be complementary to the frustoconical profile 513 of the inner inner femoral wall 509, and the frustoconical profile 537 of the second wall 536 can be complementary to the frustoconical profile 515 of the inner outer femoral wall 511. For example, during engagement of the prosthesis assembly 500, the frustoconical profile 513 of the inner inner femoral wall 509 can engage the frustoconical profile 535 of the first wall 534, and the frustoconical profile 515 of the inner outer femoral wall 511 can engage the frustoconical profile 537 of the second wall 536. The frustoconical profiles, such as frustoconical profile 513, frustoconical profile 515, frustoconical profile 535, and frustoconical profile 537, can provide additional clearance between the femoral component 506 and the wall 514 while maintaining the strength of the femoral component 506 and the wall 514 compared to a stepped design or any other design that can be used to improve the clearance between the femoral component 506 and the shackle 518.

[0038] FIG. 8 is a cross-sectional view of a portion of the prosthesis assembly 500 according to an embodiment of the present application. In FIG. 8, the prosthesis assembly 500 is shown in different orientations to illustrate how different components of the prosthesis assembly 500 interact with each other during operation of the prosthesis assembly 500.

[0039] In orientation 802, the knee joint or prosthesis assembly 500 can be extended such that the bump stop 528 contacts the shackle 518 to prevent the femoral component 506 from rotating further relative to the tibial component, e.g., the tibial bearing component 504 of FIG. 5. For example, the bump stop 528 can be brought into contact with the shackle 518 to prevent further rotation (or further extension) of the prosthesis assembly 500. As shown in FIG. 8, how much rotation the prosthesis assembly 500 allows can be determined by the size of the bump stop 528. For example, the height or thickness between the surface of the bump stop 528 facing the femoral component 506 and the bump stop 528 configured to contact the shackle 518 can determine the limit of rotation of the femoral component 506 relative to the tibial bearing component 504 (see FIG. 5). For example, by reducing the thickness of the bump stop 528, more rotation can be allowed before the bump stop 528 contacts the shackle 51. To allow less rotation of the femoral component 506 relative to the tibial bearing component 504, the thickness of the bump stop 528 can be increased. In another embodiment, the shape of the surface of the bump stop 528 can be changed so as to change when the bump stop 528 contacts the shackle 518. For example, the bump stop 528 can be flat, rounded, or any other shape that can affect the amount of rotation of the femoral component 506 relative to the tibial bearing component 504, etc.

[0040] In an embodiment, the system can include a number of bump stops 528 for the purpose of providing a number of rotational angles of the femur component 506 relative to the tibia bearing component 504. Here, the system can provide a number of bump stops 528 such that the bump stops 528 can be selected before or during the assembly of the prosthesis assembly 500, or after the implantation of the prosthesis assembly 500, in order to adjust the amount of rotation of the femur component 506 relative to the tibia bearing component 504 before the bump stops 528 contact the shackle 518. For example, a surgeon can implant the prosthesis assembly 500 and determine an appropriate bump stop 528 based on a range of motion test or any other metric. In another embodiment, the bump stop 528 can be changed while the patient's knee is healing. For example, the bump stop 528 can initially be large in order to prevent a greater rotation of the femur component 506 relative to the tibia bearing component 504, and as the patient heals, the bump stop 528 can be changed to a smaller sized bump stop 528 in order to allow for more rotation of the femur component 506 relative to the tibia bearing component 504.

[0041] In orientation 804, the knee joint and prosthesis assembly 500 can be articulated to rotate the femur component 506 about the hinge axis 512 to move the bump stop 528 away from the shackle 518. For example, the state of the prosthesis assembly 500 or the knee joint where the bump stop 528 is furthest from the axis can be referred to as the flexed state. In the flexed state, the bump stop 528 may be exposed or accessible from the front of the prosthesis assembly 500. In the flexed state, the bump stop 528 can be serviced. For example, the bump stop 528 can be removed or replaced with a bump stop of a different size. As can be seen from FIG. 8, the bump stop 538 can include a ridge or bulge that can fit within a seat or groove of the femur component 506 such that the bump stop 538 is press fit within the femur component 506 and can couple the bump stop 538 to the femur component 506. Also, the bump stop 538 can be removable by passing through the groove of the femur component 506 and through the ridge or bulge of the bump stop 538. In another embodiment, any other press fit or quick detach attachment can be used to secure the bump stop 538 within the femur component 506.

[0042] In another embodiment, the installation of the bump stop 528 inside the femoral component 506 can be adjusted to change the amount of rotation of the femoral component 506 relative to the tibial bearing component 504 before the bump stop 528 contacts the shackle 518. For example, the bump stop 528 can include a number of ridges or protrusions that can fit into the groove of the femoral component 506 to adjust the installation of the bump stop 528 when the femoral component 506 contacts the shackle 518 and change the gap between the femoral component 506 and the shackle 518. Such adjustment can change the amount of rotation before the bump stop 528 contacts the shackle 518 and modify the amount of rotation of the femoral component 506 relative to the tibial bearing component 504.

[0043] In the embodiment shown in orientation 806, the bump stops 528 in orientations 802 and 804 can be removed and replaced with bump stops such as bump stops 528 of different sizes as shown in orientations 806 and 808. As shown in orientation 806, the bump stop 528 can be replaced with a larger version of the bump stop 528. As discussed above, a larger version of the bump stop 528 can contact the shackle 518 earlier and prevent the rotation of the femoral component 506 relative to the tibial bearing component 504. In another embodiment, the size of the bump stop 528 can be reduced to increase the amount of rotation of the femoral component 506 relative to the tibial bearing component 504.

[0044] As shown in orientation 808, by installing bump stops, such as bump stops 528 of different sizes shown in orientations 806 and 808, the amount of rotation of the femoral component 506 relative to the tibial bearing component 504 can be modified. As shown in orientation 808, a bump stop 528 of increased size compared to the bump stops 528 in orientations 802 and 804 can reduce the amount of rotation of the femoral component 506 relative to the tibial bearing component 504.

[0045] The following non-limiting examples detail several aspects of the subject matter for solving problems and, among other things, providing the advantages discussed herein.

Example

[0046] Example 1 is a constrained knee prosthesis assembly, comprising a tibial tray, a tibial bearing component including an articular surface, a hinge post extending through the tibial bearing component and at least partially received within a recess of the tibial tray, a femoral component configured to contact the articular surface of the tibial bearing component and articulate with the tibial bearing component, a shackle coupled to the hinge post at a first end and configured to be inserted between the medial and lateral condyles of the femoral component, the shackle including a first side and a second side opposite the first side, a wall positioned between the femoral component and the shackle and engaged by the femoral component, the wall including a first wall configured to cover the first side of the shackle and a second wall configured to cover the second side of the shackle, the first wall being attached to the second wall, and a hinge shaft configured to fix the femoral component relative to the shackle.

[0047] In Example 2, the subject matter of Example 1 is a bump stop removably attached to the femur component, the bump stop configured to contact the shackle at a set limit of rotation of the femur component relative to the tibial bearing component.

[0048] In Example 3, the subject matter of Example 2 includes that the bump stop is configured to be removed when the knee joint is in a flexed state.

[0049] In Example 4, the subject matter from Example 2 to Example 3 includes that the size of the bump stop determines a set limit of rotation of the femur component relative to the tibial bearing component.

[0050] In Example 5, the subject matter of Example 4 includes that the bump stop is configured to be selectively serviceable.

[0051] In Example 6, the subject matter from Example 1 to Example 5 includes that the first wall is removably attached to the second wall.

[0052] In Example 7, the subject matter of Example 6 includes that the first wall and the second wall are coupled by an engagement mechanism.

[0053] In Example 8, the subject matter of Example 7 includes that the engagement mechanism includes a dovetail connection between the first wall and the second wall.

[0054] In Example 9, the subject matter from Example 6 to Example 8 includes that the outer surface of the first wall at least partially includes a first frustoconical profile.

[0055] In Example 10, the subject matter of Example 9 includes that the outer surface of the second wall at least partially includes a second frustoconical profile.

[0056] In Example 11, the subject matter of Example 10 includes that the inner wall of the medial condyle of the femoral component includes a third frustoconical profile complementary to the first frustoconical profile.

[0057] In Example 12, the subject matter of Example 11 includes that the inner wall of the lateral condyle of the femoral component includes a fourth frustoconical profile complementary to the second frustoconical profile.

[0058] Example 13 is a constrained knee prosthesis assembly, including a tibial tray, a tibial bearing component including an articular surface, a hinge post extending through the tibial bearing component and at least partially received within a recess of the tibial tray, a femoral component contacting the articular surface of the tibial bearing component, a shackle coupled to the hinge post at a first end and configured to be inserted between the medial and lateral condyles of the femoral component, a wall positioned between the femoral component and the shackle and engaged by the femoral component, a hinge shaft configured to fix the femoral component relative to the shackle, and a bump stop removably attached to the femoral component and configured to contact the shackle at a set limit of rotation of the femoral component relative to the tibial bearing component.

[0059] In Example 14, the subject matter of Example 13 includes that the bump stop is configured to be selectively removed.

[0060] In Example 15, the subject matter of Examples 13 to 14 includes that the size of the bump stop determines a set limit of rotation of the femoral component relative to the tibial bearing component before the bump stop contacts the shackle.

[0061] Example 16 is a constrained knee prosthesis assembly, comprising a tibial tray, a tibial bearing component including an articular surface, a hinge post extending through the tibial bearing component and at least partially received within a recess of the tibial tray, a femoral component contacting the articular surface of the tibial bearing component, facing the intercondylar region, and including an inner medial condylar wall facing the intercondylar region and including a first frustoconical profile, and an inner lateral condylar wall facing the intercondylar region and including a second frustoconical profile, a shackle coupled to the hinge post at a first end and configured to be inserted within the intercondylar region, the shackle including a first side and a second side opposite the first side, a wall positioned between the femoral component and the shackle so as to cover the first side and the second side of the shackle, the wall including a third frustoconical profile complementary to the first frustoconical profile of the inner medial condylar wall and a fourth frustoconical profile complementary to the second frustoconical profile of the inner lateral condylar wall, and a hinge shaft configured to fix the femoral component relative to the shackle.

[0062] In Example 17, the subject matter of Example 16 includes a bumper stop removably attached to the femoral component and configured to contact the shackle at a set limit of rotation of the femoral component relative to the tibial bearing component.

[0063] In Example 18, the subject matter of Example 17 includes that the bumper stop is configured to be removed when the knee joint is in a flexed state.

[0064] In Example 19, the subject matter of Examples 17 to 18 includes that the size of the bumper stop determines a set limit of rotation of the femoral component relative to the tibial bearing component when the bumper stop contacts the shackle.

[0065] In Example 20, the subject matter of Examples 17 to 19 includes that the bump stop is configured to be selectively maintainable.

[0066] Example 21 is an apparatus including means for implementing any one of Examples 1 to 20.

[0067] Example 22 is a system for implementing any one of Examples 1 to 20.

[0068] Example 23 is a method for implementing any one of Examples 1 to 20.

[0069] The above detailed description includes references to the accompanying drawings that form a part of this detailed description. The drawings show, by way of illustration, specific embodiments that are practicable. These embodiments are also referred to herein as "examples". Such examples may include other elements in addition to the elements shown or described. However, the inventors also contemplate examples that include only the elements shown or described. Further, the inventors contemplate examples using any combination or substitution of the things shown or described (or one or more aspects thereof) with respect to a particular example (or one or more aspects thereof) or with respect to any of the other examples (or one or more aspects thereof) shown or described herein.

[0070] All publications, patents, and patent documents mentioned in this specification are incorporated herein in their entirety as if individually incorporated by reference. If there are any conflicts in usage between this specification and these documents, the usage in the incorporated references should be considered to supplement that of this specification.

[0071] As used herein, the term "a" or "an" is used to include one or more, regardless of any other instances or uses such as "at least one" or "one or more", as is common in patent documents. In this specification, unless otherwise indicated, the term "or" is used to mean non-exclusive or, or "A or B" is used to include "A but not B", "B but not A", and "A and B". In the appended claims, the terms "including" and "in which" are used as plain English equivalents of the terms "comprising" and "wherein", respectively. Also, in the following claims, the terms "including" and "comprising" are open-ended. That is, a system, device, article, or process that includes other elements in addition to the elements listed after such terms in the claims is still considered to be within the scope of that 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.

[0072] As used herein, the term "about" 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 recited numerical values. Generally, the term "about" is used herein to modify a numerical value by a difference of 10% above and below the recited value. In one aspect, the term "about" means ± 10% of the numerical value of the numbers with which it is used. Thus, about 50% means in the range of 45% to 55%. Numerical ranges recited 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. Also, numerical ranges recited herein by endpoints include sub-ranges 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. It should also be understood that all numbers and fractions thereof are presumed to be modified by the term "about".

[0073] The above description is not intended to be limiting, but rather exemplary. For example, the above-described embodiments (or one or more aspects thereof) may be used in combination with each other. For example, other embodiments may be used by those skilled in the art upon reviewing the above description. The abstract is provided to enable the reader to quickly ascertain the content of the technical disclosure, and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above detailed description, various features may be grouped together in order to simplify the disclosure. This should not be construed as intending that any feature of the disclosed subject matter that is not claimed is essential to any of the claims. Rather, the inventive subject matter may lie in less than all of the features of a particular disclosed embodiment. Accordingly, the following claims are incorporated into the detailed description herein, with each claim standing on its own as a separate embodiment. The scope of the embodiments must be determined with reference to the appended claims along with the full scope of equivalents to which the claims are entitled. According to aspect (1), a constrained knee prosthesis assembly comprising a tibial tray, a tibial bearing component including an articular surface, a hinge post extending through the tibial bearing component and at least partially received within a recess of the tibial tray, a femoral component configured to contact the articular surface of the tibial bearing component and articulate with the tibial bearing component, a shackle coupled to the hinge post at a first end and configured to be inserted between the medial and lateral condyles of the femoral component, a first side, and a second side opposite the first side, the shackle including, a wall positioned between the femoral component and the shackle and engaged by the femoral component, A first wall configured to cover the first side portion of the shackle, and, A second wall configured to cover the second side portion of the shackle, wherein the first wall is attached to the second wall, the second wall, including the wall; A hinge shaft configured to fix the femoral component to the shackle, and, a prosthesis assembly including the same. According to aspect (2), a bumper stop removably attached to the femoral component, the bumper stop being configured to contact the shackle at a set limit of rotation of the femoral component relative to the tibial bearing component. According to aspect (3), the bumper stop is configured to be removed when the knee joint is in a flexed state. According to aspect (4), the size of the bumper stop determines a set limit of rotation of the femoral component relative to the tibial bearing component. According to aspect (5), the bumper stop is configured to be selectively maintainable. According to aspect (6), the first wall is removably attached to the second wall. According to aspect (7), the first wall and the second wall are coupled by an engagement mechanism. According to aspect (8), the engagement mechanism includes a dovetail connection between the first wall and the second wall. According to aspect (9), the outer surface of the first wall includes at least partially a first frustoconical profile. According to aspect (10), the outer surface of the second wall includes at least partially a second frustoconical profile. According to aspect (11), the inner wall of the medial condyle of the femoral component includes a third frustoconical profile complementary to the first frustoconical profile. According to aspect (12), the inner wall of the outer condyle of the femur component includes a fourth frustoconical profile that is complementary to the second frustoconical profile. According to aspect (13), a constrained knee prosthesis assembly, a tibial tray, a tibial bearing component including an articular surface, a hinge post extending through the tibial bearing component and at least partially received within a recess of the tibial tray, a femur component in contact with the articular surface of the tibial bearing component, a shackle coupled to the hinge post at a first end and configured to be inserted between the medial and lateral condyles of the femur component, a wall positioned between the femur component and the shackle and engaged by the femur component, a hinge shaft configured to fix the femur component relative to the shackle, a bump stop removably attached to the femur component and configured to contact the shackle at a set limit of rotation of the femur component relative to the tibial bearing component, and a prosthesis assembly including the same. According to aspect (14), the bump stop is configured to be selectively removed. According to aspect (15), the size of the bump stop determines a set limit of rotation of the femur component relative to the tibial bearing component before the bump stop contacts the shackle. According to aspect (16), a constrained knee prosthesis assembly, a tibial tray, a tibial bearing component including an articular surface, a hinge post extending through the tibial bearing component and at least partially received within a recess of the tibial tray, A femoral component that contacts the articular surface of the tibial bearing component, facing the intercondylar region, including an inner medial condyle wall having a first frustoconical profile, and an inner lateral condyle wall facing the intercondylar region and having a second frustoconical profile, a femoral component including; a shackle configured to be coupled to the hinge post at a first end and inserted into the intercondylar region, a first side, and a second side opposite the first side, a shackle including; a wall positioned between the femoral component and the shackle so as to cover the first side and the second side of the shackle, a third frustoconical profile complementary to the first frustoconical profile of the inner medial condyle wall, and a fourth frustoconical profile complementary to the second frustoconical profile of the inner lateral condyle wall, a wall including; a hinge shaft configured to fix the femoral component to the shackle, a prosthesis assembly including. According to aspect (17), a bumper stop removably attached to the femoral component, the bumper stop being configured to contact the shackle at a set limit of rotation of the femoral component with respect to the tibial bearing component. According to aspect (18), the bumper stop is configured to be removed when the knee joint is in a flexed state. According to aspect (19), the size of the bumper stop determines the set limit of rotation of the femoral component with respect to the tibial bearing component when the bumper stop contacts the shackle. According to aspect (20), the bumper stop is configured to be selectively serviceable.

Claims

**Claim 1** A constrained knee prosthesis assembly comprising a tibial tray, a tibial bearing component including an articular surface, a hinge post extending through the tibial bearing component and at least partially received within a recess of the tibial tray, a femoral component configured to contact the articular surface of the tibial bearing component and articulate with the tibial bearing component, a shackle coupled to the hinge post at a first end and configured to be inserted between a medial condyle and a lateral condyle of the femoral component, a first side, and a second side opposite the first side, the shackle including a wall positioned between the femoral component and the shackle and engaged by the femoral component, a first wall configured to cover the first side of the shackle, and a second wall configured to cover the second side of the shackle, the first wall being attached to the second wall, the wall including a hinge shaft configured to fix the femoral component to the shackle, and including wherein the first wall is removably attached to the second wall, wherein an outer surface of the first wall at least partially includes a first frustoconical profile, a prosthesis assembly. **Claim 2** A bump stop removably attached to the femoral component, the prosthesis assembly of claim 1 including a bump stop configured to contact the shackle at a set limit of rotation of the femoral component relative to the tibial bearing component. **Claim 3** The prosthesis assembly of claim 2, wherein the bump stop is configured to be removed when the knee joint is in a flexed state. **Claim 4** The prosthesis assembly of claim 2, wherein the size of the bump stop determines a set limit of rotation of the femoral component relative to the tibial bearing component. **Claim 5** The prosthesis assembly of claim 4, wherein the bump stop is configured to be selectively serviceable. **Claim 6** The prosthesis assembly of claim 1, wherein the first wall and the second wall are coupled by an engagement mechanism. **Claim 7** The prosthesis assembly according to claim 6, wherein the engagement mechanism includes a dovetail connection between the first wall and the second wall.

8. The prosthesis assembly according to claim 1, wherein an outer surface of the second wall at least partially includes a second frustoconical profile.

9. The prosthesis assembly according to claim 8, wherein an inner wall of the medial condyle of the femoral component includes a third frustoconical profile complementary to the first frustoconical profile.

10. The prosthesis assembly according to claim 9, wherein an inner wall of the lateral condyle of the femoral component includes a fourth frustoconical profile complementary to the second frustoconical profile.

11. A bumper stop removably attached to the femoral component, the bumper stop configured to contact the shackle at a set limit of rotation of the femoral component relative to the tibial bearing component. The prosthesis assembly according to claim 1, comprising:

12. The prosthesis assembly according to claim 11, wherein the bumper stop is configured to be selectively removable.

13. The prosthesis assembly according to claim 11, wherein a set limit of rotation of the femoral component relative to the tibial bearing component is changed by changing the size of the bumper stop.

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