Anti-dislocation device for constrained artificial knees

Abstract

To provide anti-luxation devices for a constrained prosthetic knee.SOLUTION: A prosthesis system may include a femoral component, a tibial bearing component configured to articulate with the femoral component, a baseplate, a plurality of bushings, one or more hinge posts, and a capture element. The capture element can be configured to couple with the tibial baseplate and can have a through hole configured to allow at least a portion of the one or more hinge posts to pass through the capture element. When coupled to the tibial baseplate, the capture element is configured to be engaged by at least one of the bushings or one of the one or more hinge posts to limit distraction of the femoral component from the tibial bearing component and baseplate.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] Priority claims This application claims the benefit of U.S. Provisional Patent Application No. 63 / 434,580, filed December 22, 2022, and the benefit of U.S. Provisional Patent Application No. 63 / 450,879, filed March 8, 2023. The benefit of priority claimed herein of each of these U.S. provisional patent applications, and each of these U.S. provisional patent applications, is incorporated herein by reference in its entirety.

[0002] The present subject matter relates to orthopedic prostheses, and more particularly to orthopedic prostheses used in constrained knee construction. [Background technology]

[0003] Orthopedic procedures and prostheses are widely used to repair and / or replace damaged bones and tissues within the human body. Generally, the knee is comprised of a pair of condyles located on the distal portion of the femur. The inferior surfaces of these condyles rest on correspondingly shaped proximal plateaus on the tibia. The femur and tibia are connected by ligaments, such as the posterior cruciate ligament, lateral collateral ligament, medial collateral ligament, and anterior cruciate ligament. These ligaments provide stability to the knee joint.

[0004] A prosthetic knee joint can be considered constrained or unconstrained. For purposes of this discussion, a constrained prosthetic knee system includes a femoral prosthesis and a tibial prosthesis. These prostheses are mechanically linked, or constrained, to one another to limit relative motion between the femoral and tibial prostheses. Common mechanisms for such mechanical linkage include hinges, bands, or other linkage structures. An unconstrained prosthetic knee system includes a femoral prosthesis and a tibial prosthesis that are not mechanically linked. An unconstrained knee utilizes the patient's existing ligaments and other soft tissues to provide joint stability. With this in mind, a constrained prosthetic knee may be particularly applicable in cases where the patient is missing ligaments and / or existing ligaments do not provide sufficient support and stability to the knee.

[0005] Various constrained knee designs are known. One such design includes a hinge post. This hinge post configuration is positioned within (and has an end protruding from) the tibial baseplate and is connected to the femoral component. One hinge post configuration, for example, is the applicant's proprietary NexGen® Rotating Hinge Knee. Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure relates generally to an improved constrained knee prosthesis, and more particularly to a constrained knee prosthesis utilizing a hinge post. Some constrained knee prostheses with hinge posts utilize a design that allows the femoral component (and hinge post) to move freely generally proximally and distally relative to the tibial baseplate and tibial bearing component. This arrangement allows for distraction of the knee joint. However, the inventors have recognized that certain segments of a patient receiving a constrained knee prosthesis with a hinge post may have soft tissue within the knee joint that is insufficient to prevent distraction of the femoral component from the tibial baseplate and tibial bearing component, and subsequently, to prevent dislocation. Dislocation can result in pain and other complications for the patient.

[0007] Thus, the inventors have recognized that for this particular segment of patients with insufficient soft tissue, distraction of the femoral component from the tibial baseplate and tibial bearing component should be limited. The inventors have recognized various techniques and devices, such as capture elements, that can interact with the hinge posts and bushings of a constrained knee prosthesis to limit distraction. As used herein, the terms "limiting distraction," "limit distraction," "limits distraction," "limited distraction," or similar terms include various prosthetic configurations, as discussed further herein. For example, one example of limited distraction allows the femoral component some proximal / distal movement (e.g., from a few millimeters to a few centimeters) relative to the tibial baseplate and tibial bearing component. However, this degree of motion is ultimately limited / paused / arrested, preventing further proximal / distal motion of the femoral component, such as proximal / distal motion that could result in dislocation of the femoral component from the tibial baseplate and bearing component. This configuration for a prosthesis should be contrasted with a configuration for a prosthesis that allows for “full distraction.” In a prosthesis that allows for “full distraction,” proximal / distal motion of the femoral component relative to the tibial baseplate and bearing component is not ultimately limited / paused / arrested by the components of the prosthesis, and if insufficient soft tissue is present, dislocation of the knee joint may result. Terms such as “limiting distraction,” “limit distraction,” “limits distraction,” “limited distraction,” or similar terms include prosthesis configurations in which proximal / distal motion of the femoral component is substantially completely restricted aside from micromotion.The term "micromotion" refers to the small movements that may exist between components of a prosthesis, such as between the tibial baseplate and 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 result from, for example, a small amount of space or clearance between the components. Micromotion is distinguished from larger movements of the components, such as the proximal / distal movement of the femoral component relative to the tibial baseplate and tibial bearing components.

[0008] The inventors have recognized devices, systems, and methods that allow a patient to select between a first prosthetic assembly configured to limit distraction and a second prosthetic assembly configured to allow complete distraction. The inventors have recognized a system that reduces or minimizes the number of components to facilitate changing between the first and second prosthetic assemblies, and vice versa.

[0009] Additional features and advantages of the various embodiments provided herein are discussed and / or will become apparent to those skilled in the art.

[0010] To further illustrate the devices, systems, and methods disclosed herein, the following non-limiting examples are provided, hereafter referred to as techniques. These examples / techniques can be combined in any manner. [Means for solving the problem]

[0011] In some aspects, the technology described herein provides a prosthetic system for a constrained knee, the prosthetic system including: a femoral component; a tibial bearing component configured to articulate with the femoral component; a baseplate having a distal surface, a proximal surface opposite the distal surface and facing the tibial bearing component, an outer edge extending between the proximal surface and the distal surface, and a keel extending distally from the distal surface; a plurality of bushings each having a different configuration from one another, the plurality of bushings configured to be inserted into a recess in the baseplate; and a prosthetic baseplate configured to couple with the femoral component, the plurality of bushings configured to couple with the femoral component. and a capture element configured to couple with the base plate, the capture element having a through hole configured to allow at least a portion of the one or more hinge posts to pass through the capture element, the capture element, when coupled to the base plate, configured to be engaged by at least one bushing of the plurality of bushings or one hinge post of the one or more hinge posts to limit distraction of the femoral component from the tibial bearing component and the base plate.

[0012] In some aspects, the technology described herein relates to a prosthetic system, wherein the one or more hinge posts include a single hinge post configured to connect with at least two of the plurality of bushings.

[0013] In some aspects, the technology described herein relates to a prosthetic system wherein the one or more hinge posts include at least two hinge posts, each having a different configuration from the other.

[0014] In some aspects, the technology described herein relates to a prosthetic system in which the femoral component, the tibial bearing component, and the base plate are configured to completely distract the femoral component from the tibial bearing component and base plate by eliminating connection between the capture element and the base plate and using one of the plurality of bushings and one of the one or more hinge posts.

[0015] In some aspects, the technology described herein relates to a prosthetic system in which the capture element includes one of a snap-fit ​​component or a threaded nut configured to be at least partially received within the recess of the base plate, the capture element being configured to be selectively attachable to and detachable from the base plate.

[0016] In some aspects, the technology described herein relates to a prosthetic system in which each of the one or more hinge posts is configured to be selectively attachable to and detachable from the femoral component.

[0017] In some aspects, the technology described herein relates to a prosthetic system wherein the plurality of bushings are configured to be selectively attachable to and detachable from the one or more hinge posts.

[0018] In some aspects, the technology described herein is a method of assembling a prosthesis assembly for a constrained knee, the method including coupling a first hinge post to a femoral component, inserting a first bushing into a recess in a tibial baseplate, inserting the first hinge post into the recess when coupled to the femoral component, receiving the first hinge post with the first bushing within the recess, inserting a tibial bearing component between the femoral component and the tibial baseplate, performing an intra-operative assessment to determine whether soft tissue of the constrained knee is sufficient to limit distraction of the femoral component from the tibial bearing component and the tibial baseplate, and if the soft tissue is insufficient to limit distraction, removing the first bushing and the recess from the tibial bearing component and the tibial baseplate. and inserting the tibial bearing component between the femoral component and the tibial baseplate.

[0019] In some aspects, the technology described herein relates to a method in which positioning the capture element within the recess of the tibial baseplate includes biasing the capture element into engagement with one or more retention features of the tibial baseplate.

[0020] In some aspects, the technology described herein relates to a method in which positioning the capture element within the recess of the tibial baseplate includes threading the capture element into the tibial baseplate.

[0021] In some aspects, the technology described herein relates to a method, wherein the coupling of the second hinge post and one of the first bushing or the second bushing within the recess positions one of the first bushing or the second bushing in a desired position relative to the capture element.

[0022] In some aspects, the techniques described herein relate to methods that further include engaging the capture element with at least one of the first bushing or the second bushing or the second hinge post to limit distraction of the femoral component from the tibial bearing component and the tibial baseplate.

[0023] In some aspects, the techniques described herein are directed to a method of assembling a prosthesis assembly for a constrained knee, the method including coupling a hinge post to a femoral component, inserting a first bushing into a recess in a tibial baseplate, inserting the hinge post into the recess when coupled to the femoral component, receiving the hinge post with the first bushing within the recess, inserting a tibial bearing component between the femoral component and the tibial baseplate, performing an intra-operative assessment to determine whether soft tissue of the constrained knee sufficiently limits distraction of the femoral component from the tibial bearing component and the tibial baseplate, and is insufficient to limit distraction, removing the tibial bearing component and the hinge post from the first bushing and the recess, inserting a second bushing having a different configuration than the first bushing into the recess of the tibial baseplate, positioning a capture element within the recess of the tibial baseplate, inserting the hinge post into the recess and through the capture element when coupled to the femoral component, coupling the hinge post with the second bushing within the recess, and inserting the tibial bearing component between the femoral component and the tibial baseplate.

[0024] In some aspects, the technology described herein relates to a method in which positioning the capture element within the recess of the tibial baseplate includes biasing the capture element into engagement with one or more retention features of the tibial baseplate.

[0025] In some aspects, the technology described herein relates to a method in which positioning the capture element within the recess of the tibial baseplate includes threading the capture element into the tibial baseplate.

[0026] In some aspects, the technology described herein relates to a method, wherein the coupling of the hinge post and the second bushing within the recess positions the second bushing in a desired position relative to the capture element.

[0027] In some aspects, the techniques described herein relate to methods further including engaging the capture element with at least one of the second bushing or the hinge post to limit distraction of the femoral component from the tibial bearing component and the tibial baseplate.

[0028] In some aspects, the technology described herein relates to a method for intra-operatively determining between a first configuration for a constrained knee prosthesis assembly and a second configuration for a constrained knee prosthesis assembly, the method including coupling a hinge post with a femoral component, inserting a bushing into a recess in a tibial baseplate, coupling a tibial bearing component to the tibial baseplate, placing the femoral component on the tibial bearing component with the hinge post at least partially received by the bushing within the recess, and determining intra-operatively based on a patient's anatomy whether to couple a capture element to the tibial baseplate to limit distraction of the femoral component from the tibial bearing component and the tibial baseplate.

[0029] In some aspects, the technology described herein relates to a method wherein coupling the capture element to a tibial baseplate further includes positioning the capture element to be engaged by at least one of the bushing or hinge post to limit distraction of the femoral component from the tibial bearing component and the tibial baseplate.

[0030] In some aspects, the techniques described herein relate to a method in which determining whether to couple a capture element to the tibial baseplate based on a patient's anatomical characteristics includes performing a determination to ascertain whether the soft tissue of the constrained knee will sufficiently limit distraction of the femoral component from the tibial bearing component and the tibial baseplate.

[0031] In some aspects, the techniques described herein relate to methods further including removing the hinge post from the bushing and the tibial baseplate, separating the hinge post from the femoral component, coupling a second hinge post having a different configuration from the hinge post to the femoral component, positioning a capture element within the recess of the tibial baseplate, and inserting the second hinge post into the recess within the tibial baseplate through the capture element.

[0032] In some aspects, the technology described herein relates to a method in which inserting the second hinge post into the recess within the tibial baseplate includes coupling the hinge post to one of the bushing within the recess or a second bushing having a different configuration than the bushing.

[0033] In some aspects, the techniques described herein relate to methods further including removing the hinge post from the bushing and the tibial baseplate, removing the bushing from the recess in the tibial baseplate, inserting a second bushing having a different configuration than the first bushing into the recess, positioning a capture element within the recess in the tibial baseplate, inserting the hinge post into the recess in the tibial baseplate through the capture element, and coupling the hinge post with the bushing within the recess.

[0034] In some aspects, the technology described herein relates to a method, wherein the coupling between the hinge post and the second bushing within the recess selectively disassociates the second bushing from the capture element.

[0035] In some aspects, the technology described herein relates to a method, wherein coupling the second hinge post with one of the first bushing or the second bushing within the recess disengages the capture element from one of the first bushing or the second bushing.

[0036] In some aspects, the technology described herein relates to a prosthetic system in which one or more of the plurality of bushings are configured to be selectively attachable to and detachable from the capture element.

[0037] In the drawings, which are not necessarily to scale, like reference numerals may represent like components in different drawings. Like reference numerals with different subscripts may represent different instances of like components. The drawings generally illustrate, by way of example, but in no way by way of limitation, various embodiments discussed in the present specification. [Brief explanation of the drawings]

[0038] [Figure 1] FIG. 1 illustrates a knee joint structure that provides a suitable environment in which a constrained prosthesis assembly according to one embodiment of the present application may be utilized. [Figure 2] FIG. 2 illustrates a knee joint structure that provides a suitable environment in which a constrained prosthesis assembly according to one embodiment of the present application may be utilized. [Figure 3] FIG. 3 shows a perspective view of a constrained knee prosthesis assembly according to one embodiment of the present application. [Figure 3A]3A illustrates a perspective view of the constrained knee prosthesis assembly of FIG. 3 distracted by proximal / distal movement of the femoral component relative to the tibial baseplate and tibial bearing component according to one embodiment of the present application. [Figure 4] FIG. 4 shows an exploded view of the constrained knee prosthesis assembly of FIG. [Figure 5] FIG. 5 is a flowchart illustrating a method for assembling a constrained prosthetic knee according to an embodiment of the present application. [Figure 6] FIG. 6 is a flowchart illustrating a method for assembling a constrained prosthetic knee according to an embodiment of the present application. [Figure 7] FIG. 7 illustrates a cross-sectional view of a second embodiment of a constrained knee prosthesis assembly having a capture element configured to limit distraction of the femoral component relative to the tibial baseplate and / or tibial bearing component, according to one embodiment of the present application. [Figure 8] FIG. 8 illustrates a top view of the tibial baseplate and capture element of FIG. 7 being moved to a desired position within a recess in the tibial baseplate to limit distraction, according to one embodiment of the present application. [Figure 9A-9B] FIG. 9A shows a system and a third prosthetic assembly configured to allow complete distraction of the femoral component from the tibial baseplate and / or tibial bearing component according to one embodiment of the present application, and FIG. 9B shows a system with a fourth prosthetic assembly having many of the same components as the third prosthetic assembly but adding a second bushing and capture element to limit distraction of the femoral component from the tibial baseplate and / or tibial bearing component according to one embodiment of the present application. [Figures 10A-10B] FIG. 10A shows a perspective view of an example of a first bushing including a first piece and a second piece to be used with the system of FIG. 9A and a third prosthesis assembly according to one embodiment of the present application, and FIG. 10B shows a perspective view of an example of a second bushing and capture element to be used with the system of FIG. 9B and a fourth prosthesis assembly according to one embodiment of the present application. [Figure 11] FIG. 11 illustrates a system including a femoral component, a shackle, and a hinge post with the hinge post separated from the shackle, according to one embodiment of the present application. [Figures 12A-12B] Figure 12A shows a diagram of an example hinge post that can be used with the system of Figure 11 to allow full distraction of the femoral component from the tibial baseplate and / or tibial bearing component, and Figure 12B shows various examples of hinge posts that can be used with the system of Figure 11 to allow limited distraction of the femoral component from the tibial baseplate and / or tibial bearing component. [Figure 13] FIG. 13 shows a perspective view of another embodiment of a hinge post that may be used with the constrained prosthetic knee assemblies discussed herein, including those of FIGS. 14-19. [Figure 14] FIG. 14 is a perspective view of another embodiment of a capture element and bushing separated to allow limited separation according to an embodiment of the present application. [Figure 15] FIG. 15 illustrates the process of converting a constrained prosthetic knee assembly from a bushing that allows full distraction to the bushing and capture element of FIG. 14 that provides limited distraction, according to one embodiment of the present application. [Figure 16] FIG. 16 is a perspective view of yet another embodiment of a capture element and bushing separated to allow limited separation according to an embodiment of the present application. [Figure 17] FIG. 17 shows a cross-sectional view of the tibial baseplate and tibial bearing component of a seventh constrained knee prosthesis assembly having the hinge post of FIG. 13 and the hinge post and capture element embodiment of FIG. [Figure 18] FIG. 18 is a perspective view of yet another embodiment of a capture element and bushing separated to allow limited separation according to an embodiment of the present application. [Figure 19]FIG. 19 illustrates a process for converting the components of a seventh constrained knee prosthesis from a bushing that allows full distraction to the bushing and capture element of FIG. 18 that provides limited distraction, according to one embodiment of the present application. [Figure 20] FIG. 20 shows a plan view of a hinge post that may be used with the constrained prosthetic knee assemblies discussed herein, including those of FIGS. 21A through 23. [Figure 21A] FIG. 21A is a top view of another embodiment of a capture element that combines a proximal capture element and a bushing that are initially assembled together, according to one embodiment of the present application. [Figure 21B] FIG. 21B shows a perspective view of the capture element of FIG. 21A. [Figure 21C] FIG. 21C shows a cross-sectional view of the capture element of FIGS. 21A and 21B. [Figure 22] FIG. 22 illustrates a perspective view of the now separated capture element and bushing of FIGS. 21A-21C spaced apart to allow limited separation, according to one embodiment of the present application. [Figure 23] FIG. 23 shows a cross-sectional view of the tibial baseplate and tibial bearing component of an eighth constrained knee prosthesis assembly having the hinge post of FIG. 20 and the hinge post and capture element embodiment of FIG. 22 configured to limit distraction of the femoral component from the tibial baseplate and tibial bearing component. DETAILED DESCRIPTION OF THE INVENTION

[0039] This application relates to constrained tibial prosthesis assemblies and systems that include, among other components, a tibial baseplate, a capture element, a bushing, and a hinge post. This application focuses on limiting distraction of the femoral component relative to the tibial baseplate and / or tibial bearing component through various features, techniques, and components, including the capture element, discussed herein. Limiting distraction can prevent dislocation of the knee joint and the corresponding pain, discomfort, and possible need for medical intervention.

[0040] To better understand knee replacement procedures, it may be useful to understand the relationship between bones and bone cuts that may be made to orient various temporary and permanent prosthetic components within the knee joint. Figures 1 and 2 illustrate several features of the anatomy and orientation of the knee joint. In Figure 1, a front view of a lower leg 102, including a femur 104 and a tibia 106, is shown to illustrate various lower leg axes. The femur 104 has an anatomical axis 108 that generally coincides with its intramedullary canal. The femur 104 also has a functional, or loading, axis 110 that extends from the center of the femoral head 112 to the center of the knee joint 114. The angle 116 between these two axes varies among patient populations but is generally on the order of 5 to 7 degrees, inclusive. Like the femur 104, the tibia 106 also has an anatomical axis that generally coincides with its intramedullary canal. The functional axis 118 of the tibia 106 extends from the center of the knee joint 114 to the center of the ankle region 120 and is generally collinear with its anatomical axis.

[0041] A joint line 122, about which the knee joint 114 flexes, is generally parallel to a line passing through the medial and lateral femoral condyles 124 and to the tibial plateau 126. Although the joint line 122 is shown in FIG. 1 as being perpendicular to the functional axis 110 of the femur 104 and the functional axis 118 of the tibia 106, it can extend at a varus or valgus angle. Typically, during a partial or total knee replacement procedure, 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, which in turn is perpendicular to the functional axes 110 and 118, as indicated at 128 and 130, respectively.

[0042] FIG. 2 provides a closer view of the knee joint 114 and its coordinate system. In this view, a medial / lateral axis 202 corresponds approximately to the joint line 122 (see FIG. 1 ), a proximal / distal axis 204 corresponds approximately to the functional axes 110 and 118 (see FIG. 1 ), and an anterior / posterior axis 206 is approximately perpendicular to the other two axes. Position along each of these axes can be indicated by arrows. These arrows can represent the medial / lateral 208, anterior / posterior 210, and proximal / distal 212 positions of the inserted prosthetic components. Rotation about each of these axes can also be indicated by arrows. Rotation about the proximal / distal axis 204 can anatomically correspond to external rotation of the femoral component, while rotation about the anterior / posterior axis 206 can correspond to the extension plane tilt of the component, and rotation about the medial / lateral axis 202 can correspond to the varus / valgus angle of the component. Depending on the location of the configured proximal tibial cut 130 (see FIG. 1 ), 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 coaptation line 122, the extension gap, varus / valgus angle 214, or extension plane angle 216.

[0043] 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., a direction away from the patient's torso. Of course, when the terms "proximal" and "distal" are used, they should be interpreted as if the patient were standing with the knee 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 back side of the patient, e.g., the back side of the knee. Similarly, "anterior" means the front side of the patient, e.g., the front side of the knee. Thus, "posterior" means the opposite direction of "anterior." Similarly, the term "lateral" means the opposite direction of "medial." The term "medial / lateral direction" means either from the inside to the outside or from the outside to the inside. The term "proximal / distal" means proximal to distal or distal to proximal. The term "anterior / posterior" means anterior to posterior or posterior to anterior.

[0044] As used herein, the "outer edge" of a tibial baseplate refers to any outer edge when viewed in a top view, e.g., in a generally lateral anatomical plane. Alternatively, the outer edge of a tibial baseplate can be any outer edge when viewed in a bottom view, e.g., in a generally lateral plane, looking at the distal surface configured to contact the resected proximal surface of the tibia.

[0045] 3 shows a prosthesis assembly 300 for a constrained knee. The prosthesis assembly 300 may include a tibial baseplate 302, a tibial bearing component 304 (sometimes called a meniscal component, poly, articular component, or bearing), a femoral component 306, and a hinge post 308.

[0046] The tibial bearing component 304 can be coupled to and positioned on top of the proximal surface 310 of the tibial baseplate 302. The tibial bearing component 304 can be constructed from 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 to those skilled in the art. The prosthesis assembly 300 includes the femoral component 306 and the tibial baseplate 302 that are mechanically linked to one another. This is achieved by a hinge post 308 and other components further shown and discussed in FIG. 4 . The hinge post 308 is coupled to the femoral component 306 and is received within a recess 309 in the tibial bearing component 304 and a recess 322 in the tibial baseplate 302 (see FIG. 4 ).

[0047] 3A illustrates a knee joint distraction. Specifically, the femoral component 306 is moved generally proximally / distally away from the tibial bearing component 304 and the tibial baseplate 302 (as indicated by arrow A1). If insufficient soft tissue remains within the knee joint to hold the femoral component 306 on the tibial bearing component 304 in the manner shown in FIG. 3, dislocation of the knee joint may occur. The movement between the femoral component 306, the tibial bearing component 304, and the tibial baseplate 302 creates a predetermined distance (gap) between the articular surfaces of the femoral component 306 and the tibial bearing component 304. Because the hinge post 308 remains at least partially retained within the recesses of the tibial baseplate 302 and / or tibial bearing component 304 in the embodiment of FIG. 3A, distraction of the femoral component 306 from the tibial bearing component 304 and tibial baseplate 302 occurs generally along the proximal / distal axis 204 and along the direction 212 shown in FIG. 2. However, if the hinge post 308 becomes disengaged from the recesses 309 and 322 (see FIG. 4), dislocation of the knee joint can result. Dislocation can be painful and can also lead to other complications for the patient.

[0048] FIG. 4 shows an exploded view of the prosthesis assembly 300, tibial baseplate 302, tibial bearing component 304, femoral component 306, and hinge post 308, further showing hinge axle 312, poly box 314, axle bushing 316, shackle 318, and bushing 320.

[0049] 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 of the tibial bearing component 304, which is threadably 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 defined at least in part by a keel 324 of the tibial baseplate 302. The hinge post 308 may be movable (e.g., rotatable and / or distractible as shown in FIG. 3A ) relative to the tibial bearing component 304 and / or the tibial baseplate 302. The hinge post 308 may be rotatably coupled to the femoral component 306 via a hinge axis 312. Thus, with the femoral component 306 and the tibial baseplate 302 mechanically linked, a longitudinal axis LA defining the centerline of the hinge post 308 may define a rotation / articulation axis ARA for the knee joint.

[0050] During assembly, the shackle 318 can be positioned between opposing walls of the poly box 314. When assembled onto the hinge axle 312, the axle bushing 316 additionally resides within an opening in the proximal portion of the shackle 318. The shackle 318 and hinge post 308 can be constructed from any suitable material, such as a titanium alloy or a cobalt-chromium alloy, while the axle bushing 316 and poly box 314 can be constructed from a different material, such as a plastic, such as UHMWPE. The axle bushing 316 acts as a bearing between the shackle 318 and the hinge axle 312. The poly box 314 acts as a bearing between the femoral component 306 and the shackle 318.

[0051] With the system of components 326 illustrated in the prosthesis assembly 300 of FIG. 4, knee distraction is not limited by capture elements or other mechanisms of the prosthesis assembly 300. In this manner, the system 326 provides components configured for full distraction when assembled. Therefore, as previously described, the soft tissue of the knee is relied upon to limit distraction between the femoral component 306, the tibial baseplate 302, and the tibial bearing component 304. The bushing 320 can be configured to be inserted into at least the recess 322 of the tibial baseplate 302. In some embodiments, the bushing 320 can also be inserted into or through the recess 309 (see FIG. 3 ) of the tibial bearing component 304. The bushing 320 can be configured to receive 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 may be movable in a generally proximal / distal direction relative to the bushing 320, such as during distraction depicted in FIG. 3A.

[0052] FIG. 5 is a flowchart illustrating a method 400 for assembling a prosthesis assembly for a constrained knee. The method 400 can include a system of orthopedic components (e.g., system 326 and additional components as discussed further herein). The method 400 can provide a system of components for constructing a constrained prosthesis assembly configured for full distraction of the femoral component from the tibial bearing component and / or tibial baseplate, or for limited distraction of the femoral component from the tibial bearing component and / or tibial baseplate (402). FIG. 4 illustrates an example of system 326 configured for full distraction of the femoral component from the tibial bearing component and / or tibial baseplate. Further examples of systems and prosthesis assemblies configured for full distraction are illustrated, for example, in connection with FIG. 9A. FIGS. 7 and 9B illustrate systems and prosthesis assemblies for constructing a constrained prosthesis assembly configured for limited distraction of the femoral component from the tibial bearing component and / or tibial baseplate.

[0053] Method 400 includes determining 404 whether a complete joint release is desired. This determination process may include determining the condition, function, and quantity of soft tissue within the knee joint, including the number and condition of remaining ligaments. The determination process may also include physician-directed release of the knee joint, performing a range of motion of the knee joint, measuring gaps between bones and / or soft tissue within the knee joint, such as measuring the extension gap discussed in connection with FIGS. 1 and 2, or the like. Some or all of these determinations may be performed before or after implantation of the femoral component, tibial bearing component, tibial baseplate, and / or other components.

[0054] If the physician determines, based on the patient's anatomy, that the knee is sufficient to maintain the femoral component mechanically linked to the tibial baseplate during full distraction (e.g., knee dislocation is unlikely), the method 400 can implement a first constrained prosthetic assembly configured to allow full distraction of the femoral component from the tibial bearing component and / or tibial baseplate (406). Alternatively, if the physician determines that the knee is insufficient to maintain the femoral component mechanically linked to the tibial baseplate during full distraction (e.g., knee dislocation is possible), the method 400 can implement a second constrained prosthetic assembly configured to allow limited distraction of the femoral component from the tibial bearing component and / or tibial baseplate (408).

[0055] 6 illustrates an example method 500 for assembling a prosthesis assembly for a constrained knee that may be used by a physician. The method 500 may include coupling a hinge post to the femoral component (502), inserting a bushing into a recess in a tibial baseplate (504), coupling a tibial bearing component to the tibial baseplate (506), placing the femoral component on the tibial bearing component with the hinge post at least partially received by the bushing within the recess (508), and determining intraoperatively based on the patient's anatomy whether to couple a capture element to the tibial baseplate to limit distraction of the femoral component from the tibial bearing component and tibial baseplate (510). Examples of systems and components for performing these various steps are discussed herein. As previously mentioned, the intraoperative determination 510 may include determining the condition, function, and quantity of soft tissue within the knee joint, including the number and condition of remaining ligaments. The determination process may also include physician-directed distraction of the knee joint, performing a predetermined range of motion of the knee joint, measuring gaps between the bones and / or soft tissues within the knee joint, such as measuring the joint extension gap discussed in connection with Figures 1 and 2, or the like. Some or all of these determinations may be performed before or after implantation of the femoral component, tibial bearing component, tibial baseplate, and / or other components. Thus, intra-operative determination 510 may include performing a determination of whether the soft tissues of the constrained knee sufficiently limit distraction of the femoral component from the tibial bearing component and tibial baseplate.

[0056] The method 500 may include coupling a capture element to the tibial baseplate, thereby positioning the capture element to be engaged by at least one of the bushing or hinge post to limit distraction of the femoral component from the tibial bearing component and baseplate. The method 500 may further include removing the hinge post from the bushing and the tibial baseplate, separating the hinge post from the femoral component, coupling a second hinge post with the femoral component, the second hinge post having a different configuration from the first hinge post, positioning a capture element within a recess in the tibial baseplate, and inserting the second hinge post into the recess in the tibial baseplate through the capture element. Inserting the second hinge post into the recess in the tibial baseplate may include coupling the hinge post to one of the bushing within the recess or a second bushing having a different configuration from the first bushing.

[0057] According to one embodiment, method 500 includes coupling a first hinge post to the femoral component, inserting a first bushing into a recess in the tibial baseplate, inserting the first hinge post into the recess when coupled to the femoral component, receiving the first hinge post with the first bushing within the recess, inserting a tibial bearing component between the femoral component and the tibial baseplate, performing an intra-operative determination to determine whether soft tissue of the constrained knee is sufficient to limit distraction of the femoral component from the tibial bearing component and the tibial baseplate, and if the soft tissue is insufficient to limit distraction, removing the tibial bearing component and the first hinge from the first bushing and the recess. and inserting the tibial bearing component between the femoral component and the tibial baseplate.

[0058] It should be noted that the step of inserting the tibial bearing component between the femoral component and the tibial baseplate may be performed before or after the steps of coupling the hinge post to the femoral component, inserting the first bushing into the recess of the tibial baseplate, and inserting the first hinge post into the recess and / or receiving the first hinge post together with the first bushing within the recess when coupled to the femoral component. Similarly, the step of inserting the tibial bearing component between the femoral component and the tibial baseplate may be performed before or after the step of inserting the second hinge post into the recess through the capture element and / or coupling the second hinge post with one of the first bushing or the second bushing within the recess when coupled to the femoral component. Thus, the above-described method need not be limited to the order of the steps described.

[0059] Positioning the capture element within the recess of the tibial baseplate may include biasing the capture element to engage one or more retention features of the tibial baseplate. Method 500 may include positioning the capture element within the recess of the tibial baseplate by threading or snapping the capture element into the baseplate. Coupling a second hinge post with one of the first bushing or the second bushing within the recess may position one of the first bushing or the second bushing in a desired position relative to the capture element. Method 500 further includes engaging a capture element with at least one of the first bushing or the second bushing or the second hinge post to limit distraction of the femoral component from the tibial bearing component and the tibial baseplate.

[0060] According to another embodiment, the method 500 includes coupling a hinge post to the femoral component, inserting a first bushing into a recess in the tibial baseplate, inserting the hinge post into the recess when coupled to the femoral component, receiving the hinge post with the first bushing within the recess, inserting a tibial bearing component between the femoral component and the tibial baseplate, and performing an intra-operative determination to determine whether soft tissue of the constrained knee sufficiently limits distraction of the femoral component from the tibial bearing component and the tibial baseplate, and determining whether the soft tissue distracts. If the first bushing and recess are insufficient to restrict the tibial bearing component and hinge post, removing the tibial bearing component and hinge post from the first bushing and recess, inserting a second bushing having a different configuration than the first bushing into the recess of the tibial baseplate, positioning a capture element within the recess of the tibial baseplate, inserting the hinge post into the recess and through the capture element when coupled to the femoral component, coupling the hinge post with the second bushing within the recess, and inserting the tibial bearing component between the femoral component and the tibial baseplate.

[0061] As with the previous embodiment, the step of inserting the tibial bearing component between the femoral component and the tibial baseplate can be performed before or after the steps of coupling the hinge post to the femoral component, inserting a first bushing into the recess of the tibial baseplate, and inserting the first hinge post into the recess and / or receiving the first hinge post together with the first bushing within the recess when coupled to the femoral component. Similarly, the step of inserting the tibial bearing component between the femoral component and the tibial baseplate can be performed before or after the steps of inserting a second bushing having a different configuration from the first bushing into the recess of the tibial baseplate, positioning a capture element within the recess of the tibial baseplate, and inserting the hinge post into the recess through the capture element and / or coupling the hinge post with the second bushing within the recess when coupled to the femoral component. Thus, the above-described method need not be limited to the order of the steps described.

[0062] Positioning the capture element within the recess of the tibial baseplate can include biasing the capture element to engage one or more retention features of the tibial baseplate. The hinge post can be coupled with a second bushing within the recess to position the second bushing in a desired location relative to the capture element. The method optionally includes engaging the capture element with at least one of the second bushing or the hinge post to limit distraction of the femoral component from the tibial bearing component and the tibial baseplate.

[0063] 7 is a cross-sectional view of a prosthesis assembly 600 having a structure similar to the previously described prosthesis assembly 300. However, the prosthesis assembly 600 differs in that it includes a capture element 601 that limits distraction of the femoral component 306 from the tibial bearing component 304 and the tibial baseplate 302. At least the tibial baseplate 302 can be configured to receive and / or couple with the capture element 601, as discussed further herein.

[0064] The cross-sectional view of FIG. 7 shows the distal surface 330 of the tibial baseplate 302, as well as the proximal surface 310 and outer edge 332. The outer edge 332 extends around the tibial baseplate 302 between the proximal surface 310 and the distal surface 330. A keel 324 extends distally from the distal surface 330 of the tibial baseplate 302. The keel 324 at least partially defines a recess 322 that receives the hinge post 608 and the bushing 620. The keel 324 can be integral (monolithic) with the remainder of the tibial baseplate 302 or can be attached thereto (e.g., via threads or another mechanical coupling mechanism). The keel 324 can be configured to extend distally and can be shaped to fit within the intramedullary canal of the tibia 106 (see FIG. 1 ) to provide fixation for the tibial baseplate 302.

[0065] The distal surface 330 may include features such as threaded openings for attachment of pegs, augments, or other components known to those skilled in the art. The distal surface 330 (and other features of the tibial baseplate, such as the keel 324) may be constructed from porous or highly porous materials that promote bone ingrowth. Highly porous biomaterials are useful as bone substitutes and as cell and tissue-receptive materials. The porosity of highly porous biomaterials may be as low as 30%, 55%, or as high as 70%, 80%, 85%, or 90%. The average pore size of highly porous materials may be, for example, 100 microns to 1000 microns. However, the use of highly porous biomaterials is not contemplated in all embodiments. For example, materials such as bone cement may be utilized as an alternative to highly porous biomaterials.

[0066] One example of such a porous or highly porous material is OsseoTi®, publicly available from Zimmer Biomet Inc. of Warsaw, Indiana. The material can include titanium or titanium alloys, as well as other materials. Such materials (including relatively non-porous or non-porous biocompatible materials) can be manufactured using additive manufacturing processes, such as laser sintering or the like. OsseoTi® is highly biocompatible, highly corrosion-resistant, and contains a highly interconnected pore architecture that mimics the porous structure of human cancellous bone, which may enhance bone integration and ingrowth. The porous or highly porous material can be fabricated to be layered on or structured with / on a relatively non-porous or non-porous biocompatible material, such as titanium, titanium alloys, stainless steel, or other materials known to those skilled in the art.

[0067] Another example of such porous or highly porous materials is manufactured using Trabecular Metal Technology®, publicly available from Zimmer Biomet Inc. of Warsaw, Indiana. Such materials may be constructed from a reticulated vitreous carbon foam substrate. This substrate is infiltrated and coated with a biocompatible metal, such as tantalum, by chemical vapor deposition (CVD) in a manner disclosed in detail in U.S. Patent No. 5,282,861 to Kaplan, the entire disclosure of which is expressly incorporated herein by reference. In addition to tantalum, other metals, such as niobium, or alloys of tantalum and niobium with each other or with other metals, may also be used. Porous tantalum structures may be constructed with various densities to selectively tailor the structure to specific applications. Specifically, as discussed in the above-incorporated U.S. Patent No. 5,282,861, porous tantalum may be fabricated with virtually any desired porosity and pore size, thereby matching the natural bone surrounding it and providing an improved matrix for bone ingrowth and mineralization.

[0068] Generally, the contemplated porous material structure may include multiple ligaments defining open spaces between them, with each ligament generally comprising a core covered by a thin metal film. The open spaces between the ligaments form a matrix of continuous channels with no dead ends, so that cancellous bone growth through the porous tantalum structure is unimpeded. Porous or highly porous materials may contain up to 70%, 85%, or more void space. Thus, porous or highly porous materials are lightweight, strong porous structures that are substantially uniform and consistent in composition, closely resembling the structure of natural cancellous bone, thereby providing a matrix into which cancellous bone can grow to enable fixation of the tibial baseplate to the patient's bone.

[0069] FIG. 7 illustrates that the prosthesis assembly 600 may include a hinge post 608 and a bushing 620 that are modified compared to the hinge post 308 and bushing 320 of the embodiment of FIG. 4 . The bushing 620 may be configured to receive at least a portion of the hinge post 608 therein. The hinge post 608 may include engagement features 607, such as threads 609. These engagement features 607 may be configured to interlock with corresponding engagement features 611, such as threads 613, of the bushing 620. The hinge post 608 and the bushing 620 may be coupled for movement together via the engagement features 607, 611. This configuration may differ from the configuration of the hinge post 308 and bushing 320 of the embodiment of FIG. 4 , which are not coupled for movement together. As such, the hinge post 308 and bushing 320 do not include engagement features such as threads. The hinge post 308 may be movable relative to the bushing 320.

[0070] 7 shows the hinge post 608 coupled at its proximal end to the shackle 318. This coupling can be via a threaded engagement 615 between the hinge post 608 and the shackle 318. The threaded engagement 615 allows the hinge post 608 and the shackle 318 to be reversibly coupled and separated from one another, allowing for changes in the configuration of the hinge post (e.g., from hinge post 308 to hinge post 608 to facilitate limited distraction, for example). The shackle 318 and hinge post 608 can extend into and be received by a recess 309 in the tibial bearing component 304. The hinge post 608 can have an engagement feature 607 (here, threads 609) located along a central or distal portion of the hinge post 608. The threads 609 and the threads 413 may be rope threads, knuckle threads, ACME threads, or other types of threads known to those skilled in the art. In some embodiments, the threads 609 may differ slightly in pitch or another geometric aspect from the threads 613 to provide a slight interference. This slight interference may attract the bushing 620 to a desired position within the recess 322 relative to the capture element 401. Such a position for the bushing 620 relative to the capture element 601 may allow a desired limited amount of distraction between the femoral component 306, the tibial bearing component 304, and the tibial baseplate 302 before engaging the bushing 620 with the capture element 601.While the embodiment of FIG. 7 contemplates that engagement of the bushing 620 with the capture element 601 pauses / stops limited distraction (movement) of the femoral component 306 relative to the tibial bearing component 304 and the tibial baseplate 302, the embodiments described in U.S. Provisional Patents entitled "ANTI-LUXATION DEVICES FOR A CONSTRAINED PROSTHETIC KNEE" and "ANTI-LUXATION DEVICES FOR A CONSTRAINED PROSTHETIC KNEE," filed on the same date (the entire contents of both of which are incorporated herein by reference), contemplate that engagement features (e.g., barbs, tabs, ribs, or other types of protrusions) are part of the hinge posts, and that engagement of these engagement features with the capture element 601 pauses / stops distraction of the femoral component 306 relative to the tibial bearing component 304 and the tibial baseplate 302. Thus, the capture element 601 is engaged by at least one of the bushing 620 and / or hinge post 608 to limit distraction of the femoral component 306 from the tibial bearing component 304 and tibial baseplate 302 .

[0071] 7, capture element 601 can be at least partially positioned within recess 322 of tibial baseplate 302, e.g., located proximal to bushing 620. Capture element 401 can have a through-hole (see, e.g., FIG. 8) configured to receive at least a portion of hinge post 608. Indeed, capture element 601 with a through-hole can be configured to allow hinge post 608 to extend distally through the capture element to engage and couple with bushing 620 as shown in FIG. 7. Capture element 601 can include components that can stop / limit movement of hinge post 608 when positioned at least partially within recess 322 and coupled to tibial baseplate 302.

[0072] 7 shows that the capture element 601 can be ring-shaped and can be received in a groove 617 of the tibial baseplate 302. The groove 617 and capture element 601 can be located distal to the proximal surface 310 of the tibial baseplate 302 such that the capture element 601 is located distal to the tibial bearing component 304. The groove 617 can communicate with and extend outward from the recess 322. At least a portion of the capture element 601 can extend into the recess 322 and interface with the hinge post 608. The portion of the capture element 601 positioned within the recess 322 can be engaged by the bushing 620 during limited distraction as described above.

[0073] FIG. 8 shows a top view of the tibial baseplate 302, thus showing the proximal surface 310 and outer edge 332. The proximal surface 310 and outer edge 332 may have a certain asymmetry relative to the medial / lateral centerline. This shape is designed to maximize tibial coverage for most knee replacement candidates. The asymmetric shape allows the medial compartment of the tibial baseplate to be relatively wider than the lateral compartment of the tibial baseplate 302. Maximized cortical bone coverage facilitates superior support for the tibial baseplate 302. The large area of ​​contact between the cortical and cancellous bone of the tibia facilitates secure, permanent fixation of the tibial baseplate 302 to the tibia.

[0074] FIG. 8 shows capture element 601 in the process of being assembled with tibial baseplate 302 (including by insertion into recess 322) to limit distraction. Additionally, capture element 601 can be removed (or never inserted) to facilitate complete distraction similar to the previous embodiment (discussed further in FIG. 9A ). Hinge post 608, shackle, femoral component, and bushing 620 are not shown in FIG. 8 for clarity. The assembly process involves inserting capture element 601 into receptacle 619 adjacent to and in communication with recess 322 and groove 617 (see FIG. 7 ). This process involves moving capture element 601 generally in a medial or lateral direction (as indicated by arrow A2) from receptacle 619 into recess 322 (e.g., to the position of FIG. 7 , fully into groove 617). Once fully inserted into recess 322, capture element 601 can receive the hinge post and, as previously described, can limit distraction by interacting with the hinge post and / or bushing. The process shown in Figure 8 can be reversed (e.g., capture element 601 can be moved in the opposite direction, from recess 322 into receptacle 619), and then capture element 601 can be removed if limited distraction is not desired.

[0075] 8 additionally shows through-hole 621 in capture element 601. Through-hole 621 is configured to allow at least a portion of hinge post 608 (see FIG. 7) to pass through the through-hole into the remainder of recess 322 and into bushing 620 (see FIG. 7).

[0076] 9A shows a cross-sectional view of a prosthesis assembly 700 having a structure similar to the previously described prosthesis assemblies 300 and 600. The femoral component (not shown) of the prosthesis assembly 700 can be fully distracted from the tibial bearing component 304 and / or the tibial baseplate 302. The prosthesis assembly 700 differs from the previous prosthesis assemblies in that it includes a modified hinge post 708 and bushing 720 compared to the embodiments of FIGS.

[0077] The bushing 720 can include a first piece 721 and a second piece 722. The first piece 721, coupled to the hinge post 708, is movable relative to the second piece 722 in conjunction with disengagement of the femoral component from the hinge post 708. In effect, the first piece 721 is configured for telescopic movement relative to the second piece 722 (including movement within and along the second piece 722). In this manner, the prosthesis assembly 700 is configured for full disengagement of the femoral component from the tibial bearing component 304 and / or tibial baseplate 302.

[0078] The first piece 721 of the bushing 720 can be configured to receive at least the smaller diameter distal portion 702 of the hinge post 708. The hinge post 708 can include engagement features 707, such as threads 709. These engagement features 707 can be configured to interlock with corresponding engagement features 711, such as threads 713, of the bushing 720. In this manner, the first piece 721 of the bushing 720 and the hinge post 708 can be coupled to one another via threaded engagement.

[0079] The second piece 722 of the bushing 720 can include threads 703 on an outer diameter that is configured to interlock with corresponding threads 705 along the recess 322 of the tibial baseplate 302. When the second piece 722 is threaded into the position shown in FIG. 9A , it is at least partially captured within the recess 322. The hinge post 708 can have a structure similar to that of the hinge post 608, but can have a smaller diameter distal portion 702 and threads 709 along the smaller diameter distal portion 702 rather than a central portion as in the embodiment of FIG. 7 .

[0080] FIG. 9B shows a cross-sectional view of a prosthesis assembly 800 that is very similar in structure to the prosthesis assembly 700 described above. However, the prosthesis assembly 700 of FIG. 9A has been modified relative to the prosthesis assembly 800 of FIG. 9B. The modifications include removing the bushing 720 (including the first piece 721 and second piece 722 of FIG. 9A) from the tibial baseplate 302 and adding a second bushing 820 and capture element 801. Notably, the prosthesis assembly 800 utilizes the same hinge post 708 utilized in the prosthesis assembly 700 of FIG. 7. Therefore, it is not necessary to separate the hinge post 708 from the shackle 318 (and the femoral component) when converting from a prosthesis assembly 700 configured for complete distraction to a prosthesis assembly 800 configured for limited distraction, or vice versa. As such, the number of components utilized for the system 826 shown in Figures 9A and 9B can be minimized.

[0081] The prosthesis assembly 800 of FIG. 9B is configured for limited distraction of the femoral component from the tibial bearing component 304 and / or tibial baseplate 302. Specifically, FIG. 9B shows a gap G between the second bushing 820 and the capture element 801. The size of the gap G can dictate the amount of distraction of the femoral component (not shown) from the tibial bearing component 304 and tibial baseplate 302. As the second bushing 820 moves proximally with the hinge post 708, contact between the second bushing 820 and the capture element 801 can limit (stop) distraction. The position of the second bushing 820 within the recess 322 can be adjusted (e.g., via small differences in thread pitch or other geometry) by the threaded engagement between the bushing 820 and the hinge post 708. This position of bushing 820 relative to capture element 801 (which defines gap G) can dictate the limited amount of distraction allowed for the femoral component.

[0082] 9A , the capture element 801 and second bushing 820 of FIG. 9B can be inserted into the recess 322 of the tibial baseplate 302. The capture element 801 may include threads 803 configured to interlock with corresponding threads 705 along the recess 322 of the tibial baseplate 302. Thus, the threads 803 along the outer diameter of the capture element 801 may be similar in pitch and other geometry to the threads 703 of the bushing 720 described above. When the capture element 801 is threaded into the position shown in FIG. 9B , it is at least partially captured within the recess 322.

[0083] The second bushing 820 can be inserted into the recess 322 prior to insertion of the capture element 801. The second bushing 820 can be coupled to the hinge post 708 in a manner similar to the first piece 721 (see FIG. 9A ) described above. Specifically, the smaller diameter distal portion 702 of the hinge post 708 can have engagement features 707, e.g., threads 709. These engagement features 707 can be configured to couple with corresponding engagement features 811, e.g., threads 813, of the second bushing 820. Thus, the second bushing 820 and the hinge post 708 can be coupled to one another through threaded engagement.

[0084] Bushing 720 and second bushing 820 are insertable into and removable from recess 322 depending on whether complete distraction or limited distraction is desired.

[0085] 10A shows a perspective view of a bushing 720 for a system 826 that includes a first piece 721 and a second piece 722. For clarity, the first piece 721 is slightly spaced apart from the second piece 722. However, such spacing may or may not occur in some embodiments (e.g., in the embodiment of FIG. 9A, no spacing occurs and the components are in contact with each other).

[0086] System 826 can be modified from bushing 720 to second bushing 820 and capture element 801 of Figure 10B. All other components of system 826 can be maintained, and in fact, most may remain assembled as shown in Figures 9A and 9B. Such modification can occur either from the configuration of Figure 10A to the configuration of Figure 10B, or from the configuration of Figure 10B to the configuration of Figure 10A.

[0087] 10B shows the relative spacing of capture element 801 from second bushing 820 (prior to limited distraction). Second bushing 820 can include an anti-rotation feature 824 along its outer diameter 825. Anti-rotation feature 824 is shown, for example, as lobe 828. Anti-rotation feature 824 provides a stop against rotational movement of second bushing 820. However, other types of anti-rotation features are contemplated, such as threads, projections, tabs, prongs, barbs, ribs, etc. Anti-rotation feature 824 can be used with any of the bushing designs shown and discussed herein (including bushing 320 of FIG. 4) and is therefore not limited to second bushing 820.

[0088] FIG. 11 illustrates one alternative embodiment of system 826. FIGS. 10A and 10B illustrate system 826 in which bushing 720 is replaced or modified with a second bushing 820. In contrast, FIG. 11 illustrates system 926 in which the hinge post may be replaced or modified with a second hinge post depending on whether complete distraction or limited distraction is desired. It should be noted that system 926 allows for the replacement of the hinge post without the need to replace a single bushing. In other embodiments, it is contemplated that both the hinge post and the bearing may be changed in conjunction with a change from a prosthesis assembly configured for complete distraction and a prosthesis assembly configured for limited distraction.

[0089] 11 illustrates a system 926 having a femoral component 306 with the hinge post 308 selectively separated from the shackle 318. A physician or other personnel can then select a desired hinge post, such as hinge post 308 or another embodiment (see, e.g., some embodiments in FIG. 12B including hinge post 608), to be coupled to the shackle 318.

[0090] For system 926 shown in FIGS. 12A and 12B, a desired hinge post for system 926 can be selected, however, the bearing used may be retained and used with hinge post 308 (see FIG. 12A) or with other hinge post designs for limited distraction of FIG. 12B. FIG. 12A illustrates an embodiment of a hinge post, such as hinge post 308, configured to fully distract the femoral component from the tibial bearing component and / or tibial baseplate, as described above with respect to FIGS. 3, 3A, and 4. The design of FIG. 12A is purely exemplary, and other designs are contemplated, including the designs of FIGS. 9A and 9B. If limited distraction of the femoral component from the tibial bearing component and / or tibial baseplate is desired, system 926 of FIG. 12B includes various other hinge post designs that may be utilized. In some embodiments, these hinge post designs may utilize the same bearing as hinge post 308 of FIG. 12A. However, in other cases, one or more of the hinge post designs may utilize a different bearing structure. One of these hinge posts, such as hinge post 608, hinge post 908, or hinge post 1008, or another design, may be selected. Any suitable capture element, such as those described herein or in U.S. Provisional Patents entitled "ANTI-LUXATION DEVICES FOR A CONSTRAINED PROSTHETIC KNEE" and "ANTI-LUXATION DEVICES FOR A CONSTRAINED PROSTHETIC KNEE," previously incorporated by reference with respect to the hinge post of FIG. 12B, may also be selected for connection with the tibial baseplate. The hinge post of FIG. 12B, when selected, can be coupled to a shackle 318 (see FIG. 11) and, by insertion into a recess in the tibial bearing component as described above, can provide limited distraction when utilized with a capture element.

[0091] 13 is a perspective view of a hinge post 1108 according to another embodiment. The hinge post 1108 can include a rear thread 1109P and a distal thread 1109D. The hinge post 1108 can additionally include a drive mechanism 1102 at a proximal end and an unthreaded middle section 1104. The threads 1109P and / or 1109D can be rope threads, round threads, ACME threads, or other types of threads known to those skilled in the art. The middle section 1104 can be positioned between the rear thread 1109P and the distal thread 1109D. The middle section 1104 and / or other sections can be slightly tapered, for example.

[0092] 14 is a perspective view of the capture element 1201 and bushing 1220 with their relative spacing prior to limited distraction of the knee joint. The bushing 1220 includes threads 1211 configured to engage, for example, threads 1109D (see FIG. 13 ) of the hinge post 1108. The bushing 1220 additionally includes two anti-rotation features 1224A and 1224B. The capture element 1201 can include external threads 1203, a through bore 1221, a drive mechanism 1223, and two anti-rotation features 1225A and 1225B. The capture element 1201 can have external threads 1203 along its outer diameter along with the through bore 1221. The through bore 1221 can include the drive mechanism 1223 as described above.

[0093] The two anti-rotation features 1224A and 1224B can be configured to engage with two corresponding anti-rotation features 1225A and 1225B. Such engagement can occur during distraction and / or rotation of the femoral component, hinge post 1108 (see FIG. 13 ), and bushing 1220. The anti-rotation features 1224A and 1224B can be proximally extending prongs or other features that can be inserted into appropriately shaped recesses 1202A and 1202B during limited distraction of the hinge post 1108 (see FIG. 13 ) and bushing 1220. This limited distraction can bring the bushing 1220 closer to the capture element 1201 than the spacing shown in FIG. 14 . The appropriately shaped recesses 1202A and 1202B can be configured between the two anti-rotation features 1225A and 1225B. Similarly, the two anti-rotation features 1225A and 1225B can be inserted into appropriately shaped recesses 1204A and 1204B in the bushing 1220 during limited distraction of the hinge post 1108 (see FIG. 13 ) and the bushing 1220. The recesses 1202A and 1202B can be shaped and sized relative to the anti-rotation features 1224A and 1224B, and the recesses 1204A and 1204B can be shaped and sized relative to the anti-rotation features 1225A and 1225B, to allow a desired limited rotation (e.g., 30 degrees or less) of the hinge post 1108 (see FIG. 13 ), the bushing 1220, and the femoral component (not shown). Such rotation can be stopped by engagement between two or more of the anti-rotation features 1224A, 1224B, 1225A, and / or 1225B.

[0094] The spacing between the capture element 1201 and the bushing 1220 can include the aforementioned gap G. The size of the gap G determines the amount of proximal distraction of the femoral component (not shown) from the tibial bearing component and tibial baseplate. Additionally, rotational gaps can be provided between the anti-rotation features 1224A, 1224B, 1225A, and 1225B to limit rotation of the femoral component. As the bushing 1220 moves proximally and / or rotates with the hinge post 1108 (see FIG. 13 ), contact between the bushing 1220 and the capture element 1201 can limit (stop) distraction.

[0095] 15 illustrates a process for converting a constrained knee prosthesis from a bushing 1320 (shown on the viewer's left) that allows full distraction to a bushing 1220 and capture element 1201 (shown on the viewer's right) that provides limited distraction according to an embodiment of the present application. The method 1300 may include removing the hinge post 1108 from the bushing 1320 from the tibial baseplate 702 in step 1302. The method 1300 removes the bushing 1320 configured for full distraction of the knee from the tibial baseplate 702 in step 1304. The bushing 1220 and capture element 1201 are inserted into the tibial baseplate 702 in step 1306. Then, in step 1308, the hinge post 1108 is connected to the shackle 318 and reinserted back into the tibial baseplate 702 connecting with the bushing 1220 and capture element 1201, thereby providing the limited distraction of the knee joint as discussed herein.

[0096] 16 shows a perspective view of the capture element 1401 and bushing 1420 with their relative spacing prior to limited distraction of the knee joint. The bushing 1420 includes threads 1411 configured to engage, for example, the threads 1109D (see FIG. 13 ) of the hinge post 1108. The bushing 1420 may be configured in the form of the bushing 1220 described above in FIGS. 14 and 15 . The bushing 1420 may differ in that a single anti-rotation feature 1424 is utilized. The capture element 1401 may include a single anti-rotation feature 1425.

[0097] The anti-rotation feature 1424 can be configured to engage a corresponding anti-rotation feature 1425. The anti-rotation feature 1424 can be a proximally extending prong or other feature that can be inserted into a suitably shaped recess 1402 in the capture element 1401 during limited distraction of the hinge post 1108 (see FIG. 13 ) and the bushing 1420. This limited distraction can bring the bushing 1420 closer to the capture element 1401 than the spacing shown in FIG. 16 . The suitably shaped recess 1402 can oppose the anti-rotation feature 1424 and can be defined in part by opposing edges of the anti-rotation feature 1425. Similarly, the anti-rotation feature 1425 can be inserted into a suitably shaped recess 1404 in the bushing 1420 during limited distraction of the hinge post 1108 (see FIG. 13 ) and the bushing 1420. Recess 1402 can be shaped and sized relative to anti-rotation feature 1424, and recess 1404 can be shaped and sized relative to anti-rotation feature 1425, to allow a desired limited rotation (e.g., 30 degrees or less) of hinge post 1108 (see FIG. 13), bushing 1220, and femoral component (not shown). Engagement of anti-rotation feature 1424 with anti-rotation feature 1425 can stop rotation and thus provide limited distraction of the knee joint.

[0098] 17 illustrates that the spacing between the capture element 1401 and the bushing 1420 can include the aforementioned gap G. The size of the gap G determines the amount of proximal distraction of the femoral component (not shown) from the tibial bearing component and tibial baseplate. Additionally, a rotational gap (see FIG. 16 ) can be provided between the anti-rotation features 1424 and 1425 to limit rotation of the femoral component. As the bushing 1420 moves proximally and / or rotates with the hinge post 1108, contact between the bushing 1420 and the capture element 1401 can limit (stop) distraction.

[0099] Figure 18 shows the capture element 1501 and bushing 1520 with their relative spacing prior to limited distraction of the knee joint. The bushing 1520 and capture element 1501 are configured in a manner very similar to the embodiment of Figure 16. The size of the anti-rotation feature 1524 has been modified to be smaller than the embodiment of Figure 16, while the anti-rotation feature 1525 has been enlarged. The anti-rotation features 1524 and 1525 can be sized appropriately to provide the desired control of knee distraction and / or rotation.

[0100] 19 illustrates a process for converting a constrained knee prosthesis from a bushing 1320 (shown on the viewer's left) that allows full distraction to a bushing 1520 and capture element 1501 (shown on the viewer's right) that provides limited distraction according to an embodiment of the present application. The method 1600 may include removing the hinge post 1108 from the bushing 1520 from the tibial baseplate 702 in step 1602. The method 1600 removes the bushing 1520 configured for full distraction of the knee joint from the tibial baseplate 702 in step 1604. The bushing 1520 and capture element 1501 are inserted into the tibial baseplate 702 in step 1606. Then, in step 1608, the hinge post 1108 is connected to the shackle 318 and reinserted back into the tibial baseplate 702 connecting with the bushing 1520 and capture element 1501, thereby providing the limited distraction of the knee joint as discussed herein.

[0101] FIG. 20 shows a perspective view of a hinge post 1708 according to another embodiment. The hinge post 1708 can include a rear thread 1709P and a distal thread 1709D. The hinge post 1708 can additionally include an unthreaded middle section 1704 having a first diameter portion 1704A and a smaller second diameter portion 1704B. The threads 1709P and / or 1709D can be rope threads, round threads, ACME threads, or other types of threads known to those skilled in the art. The middle section 1704 can be positioned between the rear threads 1709P and the distal threads 1709D. The middle section 1704 and / or other sections can be slightly tapered, for example. The distal end 1701 of the hinge post 1708 may not have threads and may be configured to pass through a capture element (see subsequent figures) and space the capture element from the distal end of the recess in the tibial baseplate as shown in FIG. 22.

[0102] 21A-21C show another embodiment of capture element 1801. This capture element combines both a proximal capture element 1801P, which can act as a bushing 1820, and a distal element 1801D. Capture element 1801 initially exists as a single component that includes scoring, gaps, or other features to separate (space) proximal capture element 1801P from distal element 1801D, but can also have an intermediate linking element 1825 that connects proximal capture element 1801P with distal element 1801D. FIGS. 21A-21C show capture element 1801 prior to threaded engagement, first with a hinge post (e.g., hinge post 1708) and then with a tibial baseplate. In FIGS. 21A and 21B, capture element 1801 is a single component with a frangible or severable connection provided by intermediate connection element 1825 between proximal capture element 1801P and distal element 1801D.

[0103] As shown in the cross-sectional view of Figure 21C, distal element 1801D, bushing 1820, has internal threads 1811 configured to engage, for example, threads 1709D (see Figure 20) of hinge post 1708. Proximal capture element 1801P has external threads 1803, throughbore 1821 (shared with distal capture element 1801D), and drive mechanism 1823. Throughbore 1821 can include drive mechanism 1823 configured in the manner described above.

[0104] FIG. 22 shows the capture element 1801 with the proximal capture element 1801P separated from the distal element 1801D. This separation process occurs when the capture element 1801 is partially seated into the recess of the tibial baseplate and then engaged by threading the hinge post 1708 into the distal element 1801D (e.g., distal threads 1709D (see FIG. 20) engage with internal threads 1811 (see FIG. 21C)). This threaded engagement acts to separate the proximal capture element 1801P from the distal element 1801D (disengaging / breaking / severing the intermediate connection element 1825 in FIGS. 21A and 21B). The distal element 1801D, threaded onto the hinge post 1708, is then carried distally further into the recess of the tibial baseplate, where it acts as a bushing 1820 similar to that previously described herein. The proximal capture element 1801P and bushing 1820 can terminate with the relative spacing shown in FIG. 22 to allow for some limited distraction of the knee joint.

[0105] Such limited distraction may allow the bushing 1820 to be relatively closer to the proximal capture element 1801P than the spacing shown in Figure 22. The recess 1802 may be shaped and sized to allow the desired limited distraction of the hinge post 1708 (see Figure 20), the bushing 1820, and the femoral component (not shown).

[0106] 23 shows that the spacing between the proximal capture element 1801P and the bushing 1820 can include the aforementioned gap G. The size of the gap G determines the amount of proximal distraction of the femoral component (not shown) from the tibial bearing component and tibial baseplate. As the bushing 1820 moves proximally with the hinge post 1108, contact between the bushing 1820 and the proximal capture element 1801P can limit (stop) distraction.

[0107] Additional notes The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are also referred to herein as "embodiments." Such embodiments may include elements in addition to those shown or described. However, the inventors also contemplate embodiments in which only the elements shown or described are provided. Furthermore, the inventors also contemplate embodiments using combinations or permutations of the illustrated and described elements (or one or more aspects thereof) with respect to the specific embodiment (or one or more aspects thereof) shown or described, or with respect to other embodiments (or one or more aspects thereof).

[0108] In this document, the terms "generally," "substantially," and "about" mean within 15 percent (±) of the provided value. The terms "a" or "an," as common in patent documents, are used to include one or more than one, independent of any other instance or use of "at least one" or "one or more." In this document, the term "or" means a non-exclusive or, whereby "A or B" is used to include "A but not B," "B but not A," and "A and B," unless otherwise specified. In this document, the terms "including" and "in which" are used as plain English equivalents of the terms "comprising" and "wherein," respectively. Also, in the claims that follow, the terms "including" and "comprising" are open-ended, i.e., systems, devices, articles, compositions, formulations, or processes that include elements in addition to those recited after such terms in a claim are still considered to be within the scope of that claim. Furthermore, in the claims that follow, the terms "first," "second," "third," etc. are used merely as labels and do not impose numerical requirements on their objects.

[0109] The above description is intended to be illustrative, not limiting. For example, the above embodiments (or one or more aspects thereof) can be used in combination with each other. Other embodiments can be used, for example, by those skilled in the art, upon review of the above description. The Abstract is provided to comply with U.S.C. § 1.72(b) to enable the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Furthermore, the grouping of various features in the above Detailed Description serves to simplify the disclosure. This should not be construed as intending that a non-claimed feature is essential to any claim. Rather, inventive subject matter lies in less than all features of a particular embodiment disclosed. Accordingly, the following claims are herein incorporated into the Detailed Description as examples or embodiments. Each claim stands on its own as a separate embodiment, and such embodiments can be combined with each other in various combinations or permutations. The scope of the present invention should be determined by reference to the appended claims, along with the full range of equivalents to which such claims are entitled. According to aspect (1), there is provided a prosthesis system for a constrained knee, comprising: a femoral component; a tibial bearing component configured to articulate with the femoral component; a base plate having a distal surface, a proximal surface opposite the distal surface and facing the tibial bearing component, an outer edge extending between the proximal and distal surfaces, and a keel extending distally from the distal surface; a plurality of bushings each having a different configuration, each bushing configured to be inserted into a recess in the base plate; one or more hinge posts configured to couple with the femoral component and configured to be received by one or more of the plurality of bushings; a capture element configured to couple with the base plate, the capture element having a through hole configured to allow at least a portion of the one or more hinge posts to pass through the capture element, the capture element configured to be engaged by at least one bushing of the plurality of bushings or one hinge post of the one or more hinge posts when coupled to the base plate to limit distraction of the femoral component from the tibial bearing component and the base plate; A prosthetic system for a constrained knee, comprising: According to aspect (2), the one or more hinge posts include a single hinge post configured to connect with at least two of the plurality of bushings. According to aspect (3), the one or more hinge posts include at least two hinge posts each having a different configuration from the other. According to aspect (4), the femoral component, the tibial bearing component, and the base plate are configured to completely separate the femoral component from the tibial bearing component and the base plate by eliminating connection between the capture element and the base plate and using one of the plurality of bushings and one of the one or more hinge posts. According to aspect (5), the capture element includes one of a snap-fit ​​component or a threaded nut configured to be at least partially received within the recess of the base plate, and the capture element is configured to be selectively attachable to and detachable from the base plate. According to aspect (6), the one or more hinge posts are configured so that each can be selectively attached to and detached from the femoral component. According to aspect (7), each of the plurality of bushings is configured to be selectively attachable to and detachable from the one or more hinge posts. According to aspect (8), one or more of the plurality of bushings are configured to be selectively attachable to and detachable from the capture element. According to aspect (9), there is provided a method of assembling a prosthesis assembly for a constrained knee, the method comprising: connecting the first hinge post to the femoral component; Inserting a first bushing into the recess of the tibial baseplate; inserting the first hinge post into the recess when coupled to the femoral component; receiving the first hinge post together with the first bushing within the recess; inserting a tibial bearing component between the femoral component and the tibial baseplate; performing an intra-operative assessment to determine whether the soft tissue of the constrained knee sufficiently limits distraction of the femoral component from the tibial bearing component and tibial baseplate; removing the tibial bearing component and the first hinge post from the first bushing and the recess if the soft tissue is insufficient to limit distraction; Separating the first hinge post from the femoral component; a second hinge post having a different configuration from the first hinge post is coupled to the femoral component; inserting one of the first bushing or a second bushing having a different configuration from the first bushing into the recess of the tibial baseplate; Positioning a capture element within the recess of the tibial baseplate; inserting the second hinge post into the recess through the capture element when coupled to the femoral component; connecting the second hinge post to one of the first bushing or the second bushing within the recess; inserting the tibial bearing component between the femoral component and the tibial baseplate; A method of assembling a prosthesis assembly for a constrained knee, comprising: According to aspect (10), positioning the capture element within the recess of the tibial baseplate includes biasing the capture element to engage one or more retention features of the tibial baseplate. According to aspect (11), positioning the capture element within the recess of the tibial baseplate includes threading the capture element into the tibial baseplate. According to aspect (12), the connection between the second hinge post and one of the first bushing or the second bushing within the recess positions one of the first bushing or the second bushing in a desired position relative to the capture element. According to aspect (13), the method further includes engaging the capture element with at least one of the first bushing or the second bushing, or the second hinge post, to limit distraction of the femoral component from the tibial bearing component and the tibial base plate. According to aspect (14), the connection between the second hinge post and one of the first bushing or the second bushing within the recess releases the connection between the capture element and one of the first bushing or the second bushing. According to aspect (15), there is provided a method of assembling a prosthesis assembly for a constrained knee, the method comprising: The hinge post is connected to the femoral component, Inserting a first bushing into the recess of the tibial baseplate; inserting the hinge post into the recess when coupled to the femoral component; receiving the hinge post together with the first bushing within the recess; inserting a tibial bearing component between the femoral component and the tibial baseplate; performing an intra-operative assessment to determine whether the soft tissue of the constrained knee sufficiently limits distraction of the femoral component from the tibial bearing component and the tibial baseplate; if the soft tissue is insufficient to limit distraction, removing the tibial bearing component and the hinge post from the first bushing and the recess; inserting a second bushing having a different configuration than the first bushing into the recess of the tibial baseplate; Positioning a capture element within the recess of the tibial baseplate; inserting the hinge post into the recess through the capture element when coupled to the femoral component; connecting the hinge post with the second bushing within the recess; inserting the tibial bearing component between the femoral component and the tibial baseplate; A method of assembling a prosthesis assembly for a constrained knee, comprising: According to aspect (16), positioning the capture element within the recess of the tibial baseplate includes biasing the capture element to engage one or more retention features of the tibial baseplate. According to aspect (17), positioning the capture element within the recess of the tibial baseplate includes threading the capture element into the tibial baseplate. According to aspect (18), the connection between the hinge post and the second bushing within the recess positions the second bushing in a desired position relative to the capture element. According to aspect (19), the method further includes engaging the capture element with at least one of the second bushing or the hinge post to limit distraction of the femoral component from the tibial bearing component and the tibial base plate. According to aspect (20), the connection between the hinge post and the second bushing within the recess selectively disengages the connection between the second bushing and the capture element.

Claims

1. 1. A prosthesis system for a constrained knee, comprising: a femoral component; a tibial bearing component configured to articulate with the femoral component; a base plate having a distal surface, a proximal surface opposite the distal surface and facing the tibial bearing component, an outer edge extending between the proximal and distal surfaces, and a keel extending distally from the distal surface; a plurality of bushings each having a different configuration, each bushing configured to be inserted into a recess in the base plate; one or more hinge posts configured to couple with the femoral component and configured to be received by one or more of the plurality of bushings; a capture element configured to couple with the base plate, the capture element having a through hole configured to allow at least a portion of the one or more hinge posts to pass through the capture element, the capture element configured to be engaged by at least one bushing of the plurality of bushings or one hinge post of the one or more hinge posts when coupled to the base plate to allow a desired amount of limited distraction of the femoral component from the tibial bearing component and the base plate; A prosthetic system for a constrained knee, comprising:

2. The prosthesis system of claim 1 , wherein the one or more hinge posts include a single hinge post configured to couple with at least two of the plurality of bushings.

3. The prosthesis system of claim 1 , wherein the one or more hinge posts include at least two hinge posts each having a different configuration from the other.

4. 2. The prosthetic system of claim 1, wherein the femoral component, the tibial bearing component, and the base plate are configured such that removing the capture element from the base plate and inserting two or more of the bushings into the recesses in the base plate completely distracts the femoral component from the tibial bearing component and the base plate.

5. 2. The prosthesis system of claim 1, wherein the capture element comprises one of a snap-fit ​​component or a threaded nut configured to be at least partially received within the recess of the base plate, the capture element being configured to be selectively attachable to and detachable from the base plate.

6. The prosthetic system of claim 1 , wherein the one or more hinge posts are each configured to be selectively attachable to and detachable from the femoral component.

7. The prosthesis system of claim 1 , wherein each of the plurality of bushings is configured to be selectively attachable to and detachable from the one or more hinge posts.

8. The prosthesis system of claim 1 , wherein one or more of the plurality of bushings are configured to be selectively attachable to and detachable from the capture element.

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