Artificial knee for cruciate ligament replacement

Abstract

To provide prostheses that replicate the function provided by both ACL and PCL, in order to provide a more anatomically correct TKR.SOLUTION: A knee joint prosthesis is capable of moving between an extended position and a flexion position. The knee joint prosthesis includes a femoral component that is configured to be mounted to a femur, a tibial component that is configured to be mounted to a tibia, a post fixedly connected to one of the femoral component and the tibial component, and a cam recess defined on the other of the femoral component and the tibial component that is configured to be engaged by the post in either the extended position or the flexion position of the knee joint prosthesis. The knee joint prosthesis may also include an artificial ligament that extends between the femoral component and the tibial component. The post and the ligament mimic one of the ACL and PCL.SELECTED DRAWING: Figure 7A

Description

Technical Field

[0001] The present invention relates to an artificial knee prosthesis used for total knee arthroplasty (TKR), and more particularly to a knee joint prosthesis having an artificial anterior cruciate ligament (ACL) and / or a posterior cruciate ligament (PCL).

Background Art

[0002] As described in Patent Document 1 for Garino (U.S. Patent Application Publication No. 2017 / 0252173), which is hereby incorporated by reference in its entirety, for all applications, artificial knees generally have three main components: a femoral component (FIGS. 1A and 1B) attached to the distal end of the femur, a tibial component (FIGS. 2A and 2B) implanted on the proximal end of the tibia, and an articular insert (FIGS. 3A and 3B) assembled on the tibial component to provide a friction surface for the femoral component. The components are designed to simulate the associated mechanics of the human knee throughout the joint and the entire range of motion of the knee. The components are generally provided in a variety of shapes with varying dimensions (identified as dimensions A-H and J-T in FIGS. 1A-3B), thus enabling the physician to select the optimal combination of components according to the patient's specific anatomy. The size and shape of the knee are influenced by various factors including the patient's age, gender, and size. Therefore, a generally fairly wide range of component inventories are generally available to enable adjustment of the artificial knee to the patient.

[0003] During normal knee construction in the case of TKR, the ACL is removed in most of all cases, and depending on the selected TKR design, the patient's PCL is either retained or replaced by some mechanism to substitute for the lost function of the PCL. Even when the PCL is retained, in many cases, a portion of the PCL must be cut or partially cut during surgery to assist in balancing the knee replacement. When the PCL is completely removed, the PCL is substituted by a post and cam mechanism.

[0004] TKR generally includes a femoral component 10, a tibial component 16, and an articular insert 22 that is present on an upper assembly portion 20 of the tibial component 16 to interact with the femoral component 10. Referring to FIGS. 1A, 1B, 3A, and 3B, an example of a typical design of a post and cam mechanism is provided. The articular insert 22 includes an extension portion 24 that protrudes into an opening 12 of the femoral component 10. A box 11 having an upwardly projecting wall is formed on an inner side of the femoral component 10 and includes an inner region that intersects the opening 12. The extension portion 24 includes a rear surface 25 that is intended to be in frictional contact with a rear surface 14 of the opening 12 when the joint is flexed. The resistance generated when the extension portion 24 is carried in contact with the rear surface 14 of the opening 12 in the femoral component 10 is intended to simulate the resistance that would be produced by a healthy posterior cruciate ligament (PCL).

[0005] A cam and post mechanism that partially replaces the function of the ACL has been manufactured by creating a cam surface between a front surface of the extension portion 24 and a front surface of the opening 12. However, this solution only provides a partial substitute for the ACL because the front side of the extension portion 24 can only contact the front side of the opening in the case of flexion of at most 0 to 20 degrees.

[0006] Another solution is to connect the femoral and tibial components with a cable-like material such as the material disclosed in Patent Document 2 (U.S. Patent No. 5,935,133), the content of which is incorporated herein by reference. However, this artificial material is typically only used to replace the PCL and not to replace the ACL.

[0007] Anatomically appropriate replacements are lacking, which can result in a TKR that is less functional than the original knee. This can cause problems during postoperative physical therapy and limit the ability or desire of patients to participate in physical activities after therapy. Almost all modern total knee replacements sacrifice the ACL or inappropriately substitute the knee joint with immature cam and post mechanisms, leaving the reconstructed knee with a movement function similar to that of a knee with ACL deficiency. Therefore, the normal movement function of the knee remains elusive. Furthermore, due to the lack of proper interaction between the ACL and PCL (both of which drive the kinematics of a normal knee), TKR reconstruction has remained in a state where it has not reached the area of creating a knee that is relatively normal for the patient.

[0008] Due to the complexity of knee joint mechanics and the difficulty for patients to adapt to artificial knees after surgery, there is a need for an anatomically appropriate knee replacement system that more accurately simulates the resilience and support previously provided by the removed ligaments. Anatomically, an embodiment of a prosthesis that reproduces the functions provided by both the ACL and PCL is desired for the purpose of providing a more appropriate TKR.

[0009] Referring now to FIG. 4, a healthy human knee is illustrated with a loop 30 depicting an exemplary artificial ACL / PCL ligament drawn over the original anatomical locations of the ACL and PCL. The section of the loop 30 that constitutes the artificial PCL is bounded by points 26A and 26B. The section of the loop 30 that constitutes the artificial ACL is bounded by points 28A and 28B.

[0010] Here, according to FIGS. 5, 6A, and 6B illustrating the embodiments disclosed in Patent Document 1 for Garino, the connection points 26a, 26b, 28a, and 28b of the artificial material provided as the ligament 44 and the length spanning between the connection points provided as the contour of the artificial ligament 44 are configured to simulate the dimensions and attachment points of the ACL and PCL within the human knee illustrated in FIG. 4. To connect the femur component 10 and the articular insert 22 of the TKR, at least one constant-length artificial ligament can be provided.

[0011] Although Patent Document 1 for Garino provides a solution to these complexities, development in this field is constantly sought to improve the mechanics of the knee joint.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Summary of the Invention

[0013] According to one embodiment of the present invention, a knee joint prosthesis has the ability to move between an extended position and a flexed position. The knee joint prosthesis includes a femoral component configured to be assembled to the femur and a tibial component configured to be assembled to the tibia, the tibial component being configured to engage with the femoral component to form the knee joint prosthesis. A first post is fixedly connected to one of the femoral component and the tibial component, and a first cam recess is defined on the other of the femoral component and the tibial component and configured to be engaged by the first post in either the extended position or the flexed position of the knee joint prosthesis. A second post is fixedly connected to one of the femoral component and the tibial component, and a second cam recess is defined on the other of the femoral component and the tibial component and configured to be engaged by the second post in either the extended position or the flexed position of the knee joint prosthesis.

[0014] In another embodiment of the present invention, a knee joint prosthesis includes a femoral component configured to be assembled to the femur and a tibial component configured to be assembled to the tibia, the tibial component being configured to engage with the femoral component to form the knee joint prosthesis. A post is fixedly connected to one of the femoral component and the tibial component, and a cam recess is defined on the other of the femoral component and the tibial component and configured to be engaged by the first post in either the extended position or the flexed position of the knee joint prosthesis. An artificial ligament is fixedly connected to the femoral component and the tibial component to simulate either the anterior cruciate ligament or the posterior cruciate ligament. The post and the ligament are oriented to cross when viewed in the sagittal plane, the frontal plane, or both the sagittal plane and the frontal plane.

[0015] In yet another embodiment of the present invention, the knee prosthesis includes a femoral component configured to be assembled to the femur and a tibial component configured to be assembled to the tibia. The tibial component is configured to engage with the femoral component to form the knee prosthesis. The femoral component and the tibial component are at least partially connected together by a toothed arrangement.

Brief Description of the Drawings

[0016] The drawings are as follows:

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DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention provides various embodiments of a knee joint prosthesis. In the figures, "A" represents the anterior side or direction, "P" represents the posterior side or direction, "M" represents the medial side or direction, the joint insert represents the lateral side or direction, "F" represents the femoral component, and "T" represents the tibial component (or the joint insert forming part of the tibial component).

[0018] Figure 7A is a cross-sectional side elevation view of a knee joint prosthesis 100 according to an exemplary embodiment of the present invention, shown in the extended position, as seen in the sagittal plane. Figure 7B is another view of the knee joint prosthesis 100 of Figure 7A, shown in the flexed position. The knee joint prosthesis 100 has the ability to rotate between the extended position of Figure 7A and the flexed position of Figure 7B.

[0019] The prosthesis 100 generally includes a femoral component 102 and an articular insert 104 that is assembled to or forms part of the tibial component.

[0020] The femoral component 102 shown in FIGS. 7A and 7B can represent a femoral component having a condyle (such as item 10) or a box (such as box 11) assembled to the femoral component. A recess 108 is formed at the lower end of the femoral component 102. The recess 108 is positioned between the condyles 106 along the medial-lateral direction. At the location where the recess 108 intersects the outer surface of the femoral component 102, an edge 111 is formed at the semi-circular boundary of the recess 108. The recess 108 is positioned at approximately the same location as the opening 12 within the femoral component 10. However, unlike the opening 12, the recess 108 is blind and includes a smooth and rounded inner surface. Two cam surfaces 110a and 110b (collectively or individually referred to as cam surface 110) are formed at opposite ends of the inner surface of the recess 108. Each cam 110 is a smooth and rounded concave surface. The radii of the cams 110 may be the same or different. The cams 110 are configured to interact with rounded posts 112a and 112b extending from the upper surface of the articular insert 104.

[0021] The articular insert 104 is similar to the articular insert 22, and the main differences between these inserts will be described below. The articular insert 104 includes two posts 112a and 112b (collectively or individually referred to as the post surface 112) extending from the bearing surface 113. Post 112a corresponds to the ACL, while post 112b corresponds to the PCL. Each rounded post 112 terminates in a convexly rounded surface. The radius of each post 112 may be the same as or substantially the same as the radius of each cam 110. The height and radius of the extension of the post 112 may be different (as shown) or the same in order to complement the geometry of the mating cam 110. According to this embodiment, the ACL post 112a has a greater height than the PCL post 112b. The posts 112 extend along respective axes Z that are perpendicular to the bearing surface 113. Alternatively, the posts 112 may extend obliquely in relation to the axis Z. The post 112 of FIG. 7A and all other posts described herein are either integral with the articular insert 22 (or other component to which the post is attached) as shown, or are connected to the articular insert 22 using machine threads, bolts, friction, adhesives, cement, or any other means known to those skilled in the art for assembling two components together.

[0022] The articular insert 104 has the ability to rotate in relation to the femoral component 102 between the extended position of FIG. 7A and the flexed position of FIG. 7B. In the extended position of the knee prosthesis 100, the condyles may rest on the bearing surface 113 of the articular insert 104, and the posts 112 are positioned in contact with their respective cams 110. As the femoral component 102 rotates relative to the articular insert 104 or vice versa, the post 112 travels along the surface of the cam 110 until the edge 111 of the recess 108 is supported on the base of the posterior post 112. The ACL post 112a may be supported on its cam 110a. Although not shown, the collateral ligaments (MCL and LCL) adjacent to the knee prosthesis 100 prevent the femoral component 102 from dislocating from the articular insert 104.

[0023] By disposing two posts 112 and two cams 110, the arrangement of the PCL and ACL is more closely mimicked compared to a conventional knee joint prosthesis having a single post and a single cam.

[0024] As described above, the recess 108 may be formed in a separate insert that can be attached to the femur component 102, similar to the box 11. A series of inserts having different recess geometries may be provided as a kit, thus enabling a medical professional to select an insert having the geometry that best fits the patient's specific anatomy.

[0025] FIG. 8 depicts a knee joint prosthesis 118 in which posts 122a and 122b are disposed on the femur component 124 and a cam 128 is defined on a recess 130 disposed on the articular insert 132 of the tibia component. The knee joint prosthesis 118 is similar to the knee joint prosthesis 100 except that the locations of the posts and the cam are exchanged. The operation of the knee joint prosthesis 118 is substantially similar to the operation of the knee joint prosthesis 100. Although not shown, the posts 122a and 122b may be formed in a separate insert that can be attached to the femur component 124, similar to the box 11.

[0026] Figure 9 depicts a knee joint prosthesis 136. The knee joint prosthesis 136 is similar to the knee joint prosthesis 100, except that one post 138 and one cam recess 140 are disposed on the femoral component 142, and one post 144 and one cam recess 146 are disposed on the articular insert 148 of the tibial component. In the extended position shown in Figure 9, the post 138 of the femoral component 142 is assembled with the cam recess 146 of the tibial articular insert 148, and the post 144 of the tibial articular insert 148 is assembled with the cam recess 140 of the femoral component 142. Although the post 138 is disposed in front of the recess 140, it should be understood that the locations of the post 138 and the recess 140 can be exchanged (along with the locations of the recess 146 and the post 144). The operation of the knee joint prosthesis 136 is substantially similar to the operation of the knee joint prosthesis 100.

[0027] Figures 10A and 10B depict an embodiment of a partial cross-sectional view of a knee joint prosthesis 150. The prosthesis 150 is similar to the prosthesis 100, and only the main differences therebetween will be described. In the knee joint prosthesis 150, posts 152a and 152b (collectively referred to as the post 152) that more closely mimic the PCL and the ACL, respectively, are disposed on the articular insert 154 (or the tibial portion itself) of the tibial portion and engage with cams 156a and 156b (collectively referred to as the cam 156) disposed on a recess 157 formed on the femoral component 158, respectively. The recess 157 extends upward from the bearing surface 155 of the prosthesis 150.

[0028] Specifically, the post 152a extending from the outer and posterior sides of the joint insert 154 to the inner and anterior sides of the femoral component 158 more closely mimics the location and geometry of the PCL. The post 152b extending from the inner and anterior sides of the joint insert 154 to the outer and posterior sides of the femoral component 158 more closely mimics the location and geometry of the ACL. The posts 152a and 152b are oriented to intersect when viewed in the sagittal plane and when viewed in the frontal plane, although the posts 152a and 152b can also be oriented to intersect when viewed in only one of these planes.

[0029] The angle "B" of each post 152 in relation to the bearing surface 155 when viewed in the sagittal plane may vary from that shown and can be adjusted to approximate the exact angle of the ACL or PCL. Similarly, the angle "D" of each post 152 in relation to the bearing surface 155 of the joint insert 154 when viewed in the frontal plane may vary from that shown and can be adjusted to approximate the exact angle of the ACL or PCL. It is noted that the angles B and D may be exaggerated in the figure. The length and diameter of each post 152 may vary from that shown and can be adjusted to approximate that of the ACL or PCL. Each post 152 does not necessarily have to extend straight along the longitudinal axis as shown, and instead may be curved to approximate the curved shape of the ACL or PCL.

[0030] Each post 152 includes a convex rounded surface that engages in a rotatable and slidable manner with the concave surface of the cam 156 of the recess 157. It is noted that the post 152 and the cam 156 are in sliding contact but are physically separated from each other. Although not shown, the recess 157 may be formed in a separate insert such as a box 11 that is removably attached to the femoral component 158.

[0031] Figure 11 depicts a modified embodiment of the knee joint prosthesis 160 that is similar to the knee joint prosthesis 150, except that the posts 159a and 159b are disposed on the femoral component 162 and engage with cams 161a and 161b, respectively, that are disposed on a recess 163 formed on the articular insert 165 (or the tibial portion itself) of the tibial portion. The locations of the posts and cams are interchangeable, although it is noted that the locations and geometries of the posts 159a and 159b continue to mimic those of the ACL and PCL, respectively. Similarly, as in the embodiment shown in FIG. 9, although not shown, each of the articular insert 165 and the femoral component 162 may include one angled post and one cam.

[0032] Figure 12 depicts a modified embodiment of the knee joint prosthesis 180. The knee joint prosthesis 180 is similar to the knee joint prosthesis 150, and the main differences will be described below. In the knee joint prosthesis 180, a post 182 that mimics the PCL is disposed on the tibial portion 184 and engages with a cam recess 186 on the femoral portion 188. An artificial ligament 190 that mimics the ACL is fixed to the tibial portion 184 and the femoral portion 188. The fixation is indicated by the lowercase "xxx" in FIG. 12.

[0033] The post 182 extends from the outer and posterior side of the articular insert 184 to the inner and anterior side of the femoral component 188 to mimic the location of the PCL. The ligament 190 extends from the inner and anterior side of the articular insert 184 to the outer and posterior side of the femoral component 188 to mimic the location of the ACL. The ligament 190, unlike the post 182, is fixedly connected to both the articular insert 184 and the femoral component 188. The post 182 and the ligament 190 are oriented to cross when viewed in the sagittal plane and the frontal plane, although the post 182 and the ligament 190 can also be oriented to cross when viewed in only one of these planes.

[0034] FIG. 13 depicts a modified embodiment of a knee joint prosthesis 192 that is similar to prosthesis 180 except that the locations of ligament 190' and post 182' are exchanged such that ligament 190' represents the PCL and post 182' represents the ACL. As an alternative to FIGS. 12 and 13, when a patient's natural ACL or PCL is preserved in a partial knee replacement, post 182 can be completely removed.

[0035] The ligaments shown herein are formed from artificial materials, preferably synthetic fibers or braids, for replacement of the ACL or PCL, and thus the artificial materials are configured in a similar manner as the respective orientations and locations of the ACL and PCL in a normal knee. Specifically, the configuration is such that the origin and insertion points of the artificial materials within the TKR will be similar to the origin and insertion points of the ACL and PCL within a normal knee.

[0036] FIG. 14 depicts a modified embodiment of a knee joint prosthesis 200 that is similar to knee joint prosthesis 150 except that the free end of the PCL post 202 includes a helical projection 204 that can be a machine thread. A cam 206 within the femoral component that houses the helical projection 204 includes a helical recess 208. The helical recess 208 interacts with the helical projection 204 to cause a slight rotation about axis Y as the knee joint prosthesis 200 moves between the extended and flexed positions. The slight rotation mimics the slight rotation felt within an actual knee joint when fully extended. The helical surfaces 204 and 208 can alternatively be provided in the form of wedge-shaped, angled or tapered surfaces.

[0037] The term "artificial" only means that it is not the original anatomical ACL or PCL ligament in its original form prior to TKR, and should not be construed as a limitation to the use of only synthetic materials. Thus, an artificial ligament can include "natural" materials such as materials created from biologically created materials, and / or can include hybrids of synthetic and natural materials. Other exemplary materials can include deformed forms of woven polyethylene similar to materials previously commercially available as Secure Strand® cables, a braided ultra-high molecular weight polyethylene (UHMWPE) cable used for surgical fixation in posterior spinal reconstruction, materials currently commercially available as Super Cables® (Kinamed, Inc., Camarillo, CA) made from UHMWPE and Nylon6 / 6.6, Gore-tex® (PTFE fibers manufactured by W.L. Gore and Associates, Inc., Newark, DE), carbon fibers, or other similar woven materials.

[0038] According to various embodiments of the present invention, for example, an artificial material in the form of an artificial ligament can be incorporated into the TKR at the time of surgery, or the TKR can be pre-assembled with the artificial material prior to surgery. Various methods and devices for connecting the ligament to the tibial component and the femoral component are described in U.S. Patent Application Publication No. 2017 / 0252173 to Garino. As described in this reference, the locking mechanism for the ends of the artificial ligament is not limited to any particular configuration and can include spherical retainers, metal clips, hooks, loops, fasteners in the form of claws, etc.

[0039] In view of the above embodiments, it should be recognized that the post, cam, and ligament can be connected to different components at different locations. Thus, the above embodiments should not be considered limiting.

[0040] Figures 15A and 15B depict side elevation views of a modified embodiment of the knee joint prosthesis 300 as seen in the sagittal plane, in which the tibial portion 302 is coupled to the femoral portion 304 by a rack and pinion type gear arrangement. It should be understood that the portions of the knee joint prosthesis 300 shown in FIGS. 15A and 15B do not represent the entire knee joint prosthesis. Rather, the portions of the knee joint prosthesis 300 shown in FIGS. 15A and 15B represent the portions of the tibial portion 302 and the femoral portion 304 that contact each other within the region of a box (such as box 11). The knee joint prosthesis 300 is shown in the extended position in FIG. 15A and in the flexed position in FIG. 15B. The teeth 306 on the tibial portion 302 mesh with the teeth 308 of the femoral portion 304, such that rotation of the tibial portion 302 causes rotation of the femoral portion 304 and vice versa.

[0041] Figures 16A - 16C depict a modified embodiment of the knee joint prosthesis 400 in which the tibial portion 402 is coupled to the femoral portion 404 by a gear arrangement. The knee joint prosthesis 400 is substantially similar to the knee joint prosthesis 300, and the main differences between these embodiments are described below.

[0042] The tibial portion 402 includes a rounded convex outer surface on which teeth 406 are disposed. The convex outer surface includes a rear segment 406a having a simple curved path following an arc and a front segment 406b following a helical path. The helical path extends inward when viewed in the anterior direction. The teeth similarly follow the trajectory of the helical path of the front segment 406b. The rear segment 406a intersects the front segment 406b stepwise.

[0043] Similarly, the femur portion 404 includes a convex outer surface with teeth 408 disposed thereon. The convex outer surface includes a rear segment 408a having a simple curved path following an arc and a front segment 408b following a helical path. The helical path extends inwardly when viewed in the forward direction. It should be understood that the teeth also follow the trajectory of the helical path of the front segment 408b. The rear segment 408a intersects the front segment 406b stepwise.

[0044] Although both the rear segment 408a and the front segment 408b are shown and described as following a helical trajectory, only one of these segments can also follow a helical trajectory.

[0045] The teeth 406 on the tibia portion 402 mesh with the teeth 408 of the femur portion 404, thus causing the rotation of the tibia portion 402 to cause the rotation of the femur portion 404 and vice versa. Similarly, as the tibia portion 402 rotates towards the extended position in the forward direction, the tibia portion 402 also moves inwardly. The slight inward rotation of the tibia portion 402 mimics the slight rotation felt within the actual knee joint when fully extended. The inward rotation is due to the helical geometry of the meshing front portions 406b and 408b.

[0046] FIG. 17 depicts a modified embodiment of the knee joint prosthesis 500 as seen in the sagittal plane, in which the tibia portion is coupled to the femur portion by the arrangement of the post 502 and the cam 504. The knee joint prosthesis 500 is substantially similar to the knee joint prosthesis 300, except that the teeth 306 and 308 are replaced by the post 502 and the cam 504 respectively. It should be understood that the teeth 406 and 408 of the knee joint prosthesis 300 can be similarly replaced by a post-cam arrangement such as the post-cam arrangement of the knee joint prosthesis 500.

[0047] As shown in FIG. 18, the arrangement of the post 506 and the cam 508 can be interchanged without departing from the scope or spirit of the present invention.

[0048] FIG. 19 is a plan view depicting a modified embodiment of a knee joint prosthesis 600 in which a tibial portion T is coupled to a femoral portion F by the arrangement of pins 602 and slots 604. The knee joint prosthesis 600 is shown in a flexed position in FIG. 19. As with other embodiments, the portions of the knee joint prosthesis 600 shown in FIG. 19 represent only the portions of the tibial portion T and the femoral portion F that contact each other within the region of a box (such as box 11), and not the entire knee joint prosthesis.

[0049] According to this embodiment, the pins 602 are disposed on the femoral portion F and the slots 604 are disposed on the tibial component T, although the reverse may also be considered applicable. The pins 602 extend vertically into the depth of the slots 604. During operation, the pins 602 travel along the length of the slots 604. The slots 604 curve in an inward direction when viewed in the anterior direction.

[0050] During operation, as the tibial portion T rotates in the anterior direction to an extended position and the pins 602 travel along the length of the slots 604, the tibial portion T also rotates in an inward direction. The slight rotation of the tibial portion T in the inward direction mimics the slight rotation felt within the actual knee joint when it is in a fully extended state. The inward movement is due to the curvature of the slots 604.

[0051] The components of the knee joint prosthesis can be manufactured from the same or similar materials. However, generally, all materials are preferably inert, do not tend to cause infection, and are otherwise safe for use as surgical implants and are approved for such use. Exemplary materials include polyethylene, surgically approved metal alloys, surgically approved ceramic materials, or combinations thereof. Any well-known material in the field of surgical implants can be used to manufacture any of the various embodiments or portions thereof according to the present invention.

[0052] In this specification, although the preferred embodiments of the present invention have been illustrated and described, it should be understood that such embodiments are provided merely as examples. Those skilled in the art may conceive of numerous variations, modifications, and substitutions without departing from the spirit of the present invention. Accordingly, the appended claims are intended to cover all such variations that fall within the spirit and scope of the present invention. The present disclosure also includes the following aspects. 〔Aspect 1〕 In a knee joint prosthesis configured to move between an extended position and a flexed position, a femoral component configured to be assembled to the femur; a tibial component configured to be assembled to the tibia and engage with the femoral component to form the knee joint prosthesis; a first post fixedly connected to one of the femoral component and the tibial component, and a first cam recess defined on the other of the femoral component and the tibial component and configured to engage with the first post in either the extended position or the flexed position of the knee joint prosthesis; a second post fixedly connected to one of the femoral component and the tibial component, and a second cam recess defined on the other of the femoral component and the tibial component and configured to engage with the second post in either the extended position or the flexed position of the knee joint prosthesis; A knee joint prosthesis comprising. 〔Aspect 2〕 The knee joint prosthesis according to Aspect 1, wherein the first post is fixedly connected to the femoral component and the second post is fixedly connected to the femoral component. 〔Aspect 3〕 The knee joint prosthesis according to Aspect 1, wherein the first post is fixedly connected to the tibial component and the second post is fixedly connected to the tibial component. 〔Aspect 4〕 The knee joint prosthesis according to Aspect 1, wherein the first post is fixedly connected to the tibial component and the second post is fixedly connected to the femoral component. 〔Aspect 5〕 The knee joint prosthesis according to Aspect 1, wherein the first post is fixedly connected to the femoral component and the second post is fixedly connected to the tibial component. 〔Aspect 6〕 The knee joint prosthesis according to Aspect 1, wherein the tibial component includes an articular insert. 〔Aspect 7〕 The knee joint prosthesis according to aspect 1, wherein each post includes a convex surface with a rounded shape, and each cam recess is a concave surface with a rounded shape. [Aspect 8] The knee joint prosthesis according to aspect 1, wherein each post is engaged with each cam recess in a sliding manner and is further disengaged from this cam recess. [Aspect 9] The knee joint prosthesis according to aspect 1, wherein either the post or the cam recess forms part of a removable insert configured to be connected to either the femoral component or the tibial component. [Aspect 10] The knee joint prosthesis according to aspect 1, wherein the first post and the second post are oriented to intersect when viewed in the sagittal plane, the frontal plane, or both the sagittal plane and the frontal plane. [Aspect 11] The knee joint prosthesis according to aspect 1, wherein the femoral component and the tibial component are in contact with each other on the bearing surface, and the post extends in a direction away from the bearing surface. [Aspect 12] The knee joint prosthesis according to aspect 1, wherein at least one of the posts and one of the cams includes a helical surface so as to cause rotation of the knee joint prosthesis as the knee joint prosthesis moves between a flexed position and an extended position. [Aspect 13] In a knee joint prosthesis configured to move between an extended position and a flexed position, a femoral component configured to be assembled to the femur; a tibial component configured to be assembled to the tibia, the tibial component being configured to engage with the femoral component to form the knee joint prosthesis; a post fixedly connected to one of the femoral component and the tibial component, and a cam recess defined on the other of the femoral component and the tibial component and configured to engage with the post in either the extended position or the flexed position of the knee joint prosthesis; an artificial ligament fixedly connected to the femoral component and the tibial component and simulating either the anterior cruciate ligament or the posterior cruciate ligament; comprising wherein the post and the ligament are oriented to intersect when viewed in the sagittal plane, the frontal plane, or both the sagittal plane and the frontal plane. Knee joint prosthesis. [Aspect 14] The knee joint prosthesis according to aspect 13, wherein the post is fixedly connected to the femoral component, and the cam recess is defined within the tibial component. 〔Aspect 15〕 The knee joint prosthesis according to aspect 13, wherein the post is fixedly connected to the tibial component, and the cam recess is defined within the femoral component. 〔Aspect 16〕 The knee joint prosthesis according to aspect 13, wherein the post and the ligament are oriented so as to intersect in both the sagittal plane and the frontal plane. 〔Aspect 17〕 The knee joint prosthesis according to aspect 13, wherein the tibial component includes an articular insert. 〔Aspect 18〕 The knee joint prosthesis according to aspect 13, wherein each post includes a rounded convex surface and each cam recess is a rounded concave surface. 〔Aspect 19〕 The knee joint prosthesis according to aspect 13, wherein the post is engaged with the cam recess in a sliding manner and is further disengaged from the cam recess. 〔Aspect 20〕 The knee joint prosthesis according to aspect 13, wherein the post, the cam recess or the ligament forms part of a removable insert configured to be connected to either the femoral component or the tibial component. 〔Aspect 21〕 In a knee joint prosthesis configured to move between an extended position and a flexed position, a femoral component configured to be assembled to the femur; a tibial component configured to be assembled to the tibia and configured to engage with the femoral component to form the knee joint prosthesis; comprising a knee joint prosthesis, wherein the femoral component and the tibial component are connected together at least partially by a toothed arrangement. 〔Aspect 22〕 The knee joint prosthesis according to aspect 21, wherein the gear of the tibial component meshes with the gear of the femoral component, and at least one of the gears follows a spiral track to cause movement of the tibial component in an inward direction as the knee joint prosthesis is moved to the extended position. 〔Description of Reference Numerals〕

Explanation of Symbols

[0053] 10 Femoral component 12 Opening 16 Tibial component 20 Upper assembly portion 22 Joint insert 24 Extension portion 25 Rear surface 30 Loop 44, 190 Ligament 100, 118, 150, 192, 200, 3000, 400, 500 Knee joint prosthesis 102, 124, 142, 150, 158, 162, 188 Femoral component 104, 132, 148, 154 Joint insert 106 Condyle 108, 130, 140, 146, 157, 163 Depression 110, 128, 156, 504, 508 Cam 111 Edge 112, 122, 138, 144, 152, 182, 502, 506 Post 113, 155 Bearing surface

Claims

**Claim 1** In a knee joint prosthesis configured to move between an extended position and a flexed position, a femoral component configured to be assembled to the femur; a tibial component configured to be assembled to the tibia and configured to engage with the femoral component to form the knee joint prosthesis; a post fixedly connected to one of the femoral component and the tibial component, and a cam recess defined on the other of the femoral component and the tibial component and having a concave cam surface configured to engage with a rounded convex end surface of the post at the extended position of the knee joint prosthesis; an artificial ligament fixedly connected to the femoral component and the tibial component and configured to simulate either the anterior cruciate ligament or the posterior cruciate ligament; comprising the post and the artificial ligament are oriented to intersect when viewed in the sagittal plane, the frontal plane, or both the sagittal plane and the frontal plane, a knee joint prosthesis. **Claim 2** The knee joint prosthesis according to claim 1, wherein the post is fixedly connected to the femoral component and the cam recess is defined within the tibial component. **Claim 3** The knee joint prosthesis according to claim 1, wherein the post is fixedly connected to the tibial component and the cam recess is defined within the femoral component. **Claim 4** The knee joint prosthesis according to claim 1, wherein the post and the artificial ligament are oriented to intersect in both the sagittal plane and the frontal plane. **Claim 5** The knee joint prosthesis according to claim 1, wherein the tibial component includes an articular insert. **Claim 6** The knee joint prosthesis according to claim 1, wherein each post includes a rounded convex surface and each cam recess is a rounded concave surface. **Claim 7** The knee joint prosthesis according to claim 1, wherein the post is engaged with the cam recess in a sliding manner and disengaged from the cam recess in a sliding manner. **Claim 8** The knee joint prosthesis according to claim 1, wherein the post, the cam recess, or the artificial ligament forms part of a removable insert configured to be connected to the femoral component or the tibial component.

Images