Artificial knee joint, and beam members, insert members, and base plates used therein.

Abstract

To provide an artificial knee joint that may acquire properties close to a normal knee joint.SOLUTION: An artificial knee joint 1 includes: an insert member 2 embedded in a hole formed in part of a joint surface of a medial condyle MC or a lateral condyle LC of a tibia T; and a beam member 3 which is disposed downward the insert member 2, of which both ends have a length fixed to a cortical bone of the tibia T, and which supports the insert member 2 from a lower side.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an artificial knee joint, as well as a beam member, an insert member, and a base plate used therefor.

Background Art

[0002] The knee joint is a joint formed by the femur, tibia, and patella. In the knee joint, the articular cartilage at the distal end of the femur and the proximal end of the tibia, and the meniscus between them act as cushions, enabling the knee joint to operate smoothly.

[0003] However, if the knee cartilage wears out and the meniscus is damaged due to obesity, aging, etc., not only is the cushioning between the distal end of the femur and the proximal end of the tibia lost, but deformation of the knee joint also occurs and progresses over time. Also, when rheumatoid arthritis develops or the knee is injured, the knee joint may deform. When such knee joint deformation (osteoarthritis of the knee joint) occurs, the knee joint cannot operate smoothly, and the patient feels severe pain when walking, etc., and may also have difficulty walking.

[0004] As a treatment method for such osteoarthritis of the knee joint, total knee arthroplasty (TKA) is adopted. This total knee arthroplasty is a technique in which the distal end of the femur and the proximal end of the tibia are resected and the resected parts are replaced with an artificial knee joint. Even at present, many patients undergo total knee arthroplasty, which can remove pain and has effects such as enabling normal walking, and the patient satisfaction is high. Also, many artificial knee joints used for total knee arthroplasty have been developed (see Patent Documents 1 and 2).

[0005] In recent years, unicompartmental knee arthroplasty (UKA), which replaces only a part of the knee joint with an artificial knee joint, has also been adopted. Patent Document 3 below discloses a partial unicompartmental system for unicompartmental knee arthroplasty.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2013-172992 [Patent Document 2] Japanese Patent Publication No. 2001-120583 [Patent Document 3] Special Publication No. 2018-502651 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, current total knee arthroplasty and unicompartmental knee arthroplasty procedures generally cannot preserve the meniscus. Furthermore, in total knee arthroplasty, the entire articular surface is removed and replaced with an artificial knee joint, making it difficult to reproduce the original height of the articular surface. This change in the original articular surface height has led to many reports of unexpected pain and limited range of motion after surgery, resulting in limited patient satisfaction.

[0008] Therefore, the object of the present invention is to provide an artificial knee joint that can acquire characteristics close to those of a normal knee joint, as well as a beam member, insert member, and base plate used therein. [Means for solving the problem]

[0009] The artificial knee joint of the present invention comprises an insert member embedded in a part of the articular surface of the medial or lateral condyle of the tibia, The device comprises a beam member positioned below the insert member and having a length such that both ends are fixed to the cortical bone of the tibia.

[0010] With this configuration, by embedding the insert member in only a portion of the joint surface, the surface of the insert member can be made to match the surrounding remaining joint surface, thus making it possible to reproduce the original height of the joint surface. Furthermore, by reproducing the original height of the joint surface, the meniscus can be preserved. As a result, the artificial knee joint of the present invention can acquire characteristics close to those of a normal knee joint.

Brief Description of the Drawings

[0011] [Figure 1] It is a perspective view showing the usage state of an artificial knee joint. [Figure 2] It is a perspective view and a cross-sectional view showing an insert member. [Figure 3] It is a perspective view showing a beam member. [Figure 4A] It is a perspective view showing a base plate. [Figure 4B] It is a perspective view and a cross-sectional view showing the usage state of a base plate according to another embodiment. [Figure 4C] It is a plan view and a side view of a base plate according to another embodiment. [Figure 4D] It is a perspective view of a fin. [Figure 4E] It is a plan view of a base plate according to another embodiment. [Figure 4F] It is a plan view of a base plate according to another embodiment. [Figure 4G] It is a plan view of a base plate according to another embodiment. [Figure 4H] It is a plan view of a base plate according to another embodiment. [Figure 4I] It is a plan view of a base plate according to another embodiment. [Figure 4J] It is a side view of a base plate according to another embodiment. [Figure 4K] It is a plan view and a side view of a base plate according to another embodiment. [Figure 4L] It is a plan view and a side view of a base plate according to another embodiment. [Figure 5] It is a perspective view and a plan view showing a surgical procedure. [Figure 6A] It is a plan view and a front view showing the usage state of an artificial knee joint according to another embodiment. [Figure 6B] It is a plan view and a front view showing the usage state of an artificial knee joint according to another embodiment. [Figure 6C]It is a plan view and a front view showing the usage state of an artificial knee joint according to another embodiment. [Figure 6D] It is a plan view and a front view showing the usage state of an artificial knee joint according to another embodiment. [Figure 6E] It is a plan view and a front view showing the usage state of an artificial knee joint according to another embodiment. [Figure 6F] It is a plan view and a front view showing the usage state of an artificial knee joint according to another embodiment. [Figure 6G] It is a plan view and a front view showing the usage state of an artificial knee joint according to another embodiment. [Figure 6H] It is a plan view and a front view showing the usage state of an artificial knee joint according to another embodiment. [Figure 7] It is a plan view and a side view of an insert member according to another embodiment.

Mode for Carrying Out the Invention

[0012] Hereinafter, an artificial knee joint according to an embodiment of the present invention will be described with reference to the drawings. The artificial knee joint of the present invention is an artificial knee joint used in artificial knee joint replacement surgery in the treatment of osteoarthritis, rheumatoid arthritis, etc., and is characterized in that it has a structure capable of preserving the meniscus and ligaments.

[0013] [Artificial Knee Joint] FIG. 1 shows the usage state of the artificial knee joint 1. FIGS. 2 to 4 show the constituent members of the artificial knee joint 1. In the following description of the artificial knee joint 1, the direction in which the tibia T extends is referred to as the vertical direction, and the front-back direction and the left-right direction of the patient on the tibia T are referred to as the front-back direction and the left-right direction, respectively.

[0014] The artificial knee joint 1 includes an insert member 2 embedded in a part of the joint surface of the medial condyle MC or the lateral condyle LC of the tibia T, and a beam member 3 disposed below the insert member 2. Further, the artificial knee joint 1 may further include a base plate 4 disposed between the insert member 2 and the beam member 3. In FIG. 1, the insert member 2 is embedded in a part of the joint surface of the lateral condyle LC.

[0015] Insert member 2 is implanted after excising a portion of the articular surface of the medial condyle MC or lateral condyle LC of the tibia T, specifically the damaged (worn-down) portion of the articular surface. Insert member 2 is implanted after adjusting its height and surface shape so that its surface smoothly connects with the surrounding original articular surface.

[0016] It is preferable to have multiple types of insert members 2, and Figure 2 shows insert members 2a to 2c with different shapes. Figure 2 shows perspective views and cross-sectional views of insert members 2a to 2c.

[0017] Insert members 2a to 2c are generally disc-shaped. Insert member 2a is embedded in the medial condyle MC of the tibia T and has a concave curved surface. Insert member 2b is embedded in the lateral condyle LC of the tibia T and has a convex curved surface. Insert member 2c has a flat surface.

[0018] The lower surfaces of the insert members 2a to 2c have concentric stepped portions 20 into which the upper end of the cylindrical base plate 4 is fitted. If the base plate 4 is not provided, the stepped portions 20 are not formed.

[0019] The diameters of the insert members 2a to 2c are, for example, 15 to 25 mm, preferably 17 to 22 mm. In practice, multiple insert members 2a to 2c with different diameters are prepared, and the optimal size insert member 2a to 2c is selected while referring to images of the patient, such as MRI.

[0020] The thickness of the insert members 2a to 2c is, for example, 4 mm or more. Multiple insert members 2a to 2c with different thicknesses are prepared, and the insert member 2a to 2c with the optimal thickness is selected while referring to images such as the patient's MRI. This allows the surface height of the insert members 2a to 2c to match the height of the original joint surface.

[0021] Furthermore, the recess of the insert member 2a embedded in the inner condyle MC is, for example, 1 to 2 mm, and the bulge of the insert member 2b embedded in the outer condyle LC is, for example, 1 to 2 mm. The surfaces of the insert members 2a to 2c are formed to smoothly connect with the original articular surface around the embedded portion.

[0022] The insert members 2a to 2c are made of a material with high lubricity and wear resistance (for example, high-molecular-weight polyethylene).

[0023] The beam member 3 is positioned below the insert member 2, approximately horizontally, and is intended to support the insert member 2 from below. A beam member 3 that performs such a raft function is sometimes called a raft pin. Note that the beam member 3 does not necessarily need to contact the lower surface of the insert member 2. That is, the beam member 3 may support the insert member 2 via the cancellous bone within the tibia T without contacting the lower surface of the insert member 2.

[0024] The shape of beam member 3 is not particularly limited, and Figure 3 shows beam members 3a to 3c with different shapes. Figure 3 shows perspective views of beam members 3a to 3c.

[0025] The beam members 3a to 3c are rod-shaped members with a length such that both ends in the longitudinal direction are fixed to the cortical bone of the tibia T. Thus, the beam members 3a to 3c become fixed-end beams with both ends fixed to hard cortical bone. The length of the beam members 3a to 3c is, for example, 30 to 80 mm. In practice, multiple beam members 3a to 3c of different lengths are prepared, and the depth of the hole into which the beam members 3a to 3c are inserted is measured with a depth gauge during surgery to select the beam member 3a to 3c of the optimal length. The beam members 3a to 3c are prepared, for example, at a 2 mm pitch, preferably at a 1 mm pitch. The width of the beam members 3a to 3c is, for example, 2 to 8 mm.

[0026] The cross-sectional shape of beam member 3 is not particularly limited. The cross-section of beam member 3a is circular. However, the cross-section of beam member 3a may also be elliptical.

[0027] The cross-section of the beam member 3b is triangular. In the state of use, the beam member 3b may be positioned with the vertex of the triangle facing upward, as shown in Figure 3, or it may be positioned with the base of the triangle facing upward, resulting in an inverted triangular cross-section. Positioning the beam member 3b with the base of the triangle facing upward enhances its ability to support the insert member 2.

[0028] The cross-section of beam member 3c is quadrilateral. Here, the term quadrilateral includes not only rectangles as shown in Figure 3, but also squares, trapezoids, rhombuses, etc.

[0029] While beam member 3a, which has a circular cross-section, has a simple shape, beam member 3b, which has a triangular cross-section, and beam member 3c, which has a square cross-section, are preferable in terms of strength. Alternatively, beam member 3b or beam member 3c may be driven into a circular through-hole made with a drill or the like.

[0030] Beam members 3a to 3c are made of a material that is highly biocompatible and rigid (for example, titanium, stainless steel, etc.).

[0031] The base plate 4 is positioned between the insert member 2 and the beam member 3. The base plate 4 is cylindrical and fits into the stepped portion 20 formed on the lower surface of the insert member 2, supporting the outer edge of the insert member 2 from below. The thickness of the cylindrical base plate 4 is, for example, 1 mm.

[0032] Multiple base plates 4 of different heights may be prepared. This allows for height adjustment of the insert member 2 using the base plate 4 rather than the insert member 2 itself. Alternatively, a separate height adjustment plate (not shown) may be placed between the base plate 4 and the beam member 3.

[0033] The base plate 4 does not necessarily need to be in contact with the beam member 3. In other words, the base plate 4 may not be in contact with the beam member 3, and the cancellous bone of the tibia T may be interposed between them.

[0034] The shape of the base plate 4 is not particularly limited, and Figure 4A shows base plates 4a to 4d with different shapes. Figure 4A shows perspective views of base plates 4a to 4d. Figure 4B shows a perspective view and a cross-sectional view of base plate 4d in use.

[0035] The base plate 4a has a cylindrical portion 40 into which fitting holes 41 and fitting grooves 42 are formed, into which two beam members 3c having a square cross-section are fitted. The two beam members 3c are arranged in a cross shape. By combining the base plate 4a and the beam members 3c, the base plate 4a and the beam members 3c become one unit, thereby enhancing their function in supporting the insert member 2.

[0036] The base plate 4b has a bottomed cylindrical shape with a cylindrical portion 40 and a bottom portion 43. This configuration prevents the insert member 2 from sinking when a large load is applied.

[0037] The base plate 4c has a grid-like mesh section 44 formed at the lower opening of the cylindrical section 40. With this configuration, the mesh section 44 prevents the base plate 4c from sinking and reinforces the cylindrical section 40, maintaining its cylindrical shape. In addition, the increased contact area due to the mesh section 44 enhances the ability to support the base plate 4c when installed with cement.

[0038] The base plate 4d is configured such that the upper end surface of the cylindrical portion 40 is inclined with respect to a plane perpendicular to the cylindrical axis. On the other hand, the lower end surface of the cylindrical portion 40 is parallel to the plane perpendicular to the cylindrical axis. That is, the upper end surface of the base plate 4d is formed at an angle to the lower end surface. The base plate 4d is used in combination with the insert member 2d shown in Figure 4B. The upper surface of the insert member 2d is formed to be inclined with respect to the plane perpendicular to the cylindrical axis of the base plate 4d, similar to the upper end surface of the base plate 4d. Also, the stepped portion 20 of the insert member 2d is parallel to the upper surface. With this configuration, the height of the insert member 2d can be adjusted to match the height and shape of the actual articular surface of the tibia T by rotating the base plate 4d around the cylindrical axis. At this time, to prevent the insert member 2d from rotating relative to the base plate 4d, projections and grooves that fit into these projections may be provided on the contact surfaces of the stepped portion 20 of the insert member 2d and the upper end surface of the base plate 4d, respectively. The shape and number of protrusions are not particularly limited; for example, they may be at least one point-like protrusion or multiple linear protrusions extending radially from a cylindrical axis.

[0039] Figures 4C to 4L show a base plate 4 according to another embodiment. The base plate 4 may include a cylindrical portion 40 (an example of a tubular portion) and a protruding portion that projects outward from the outer circumferential surface of the cylindrical portion 40. By providing a protruding portion on the outer circumferential surface of the cylindrical portion 40, sinking of the base plate 4 can be suppressed.

[0040] Figure 4C shows a plan view and a side view of the base plate 4e, and Figure 4D shows a perspective view of the fin 45. The base plate 4e has fins 45 provided on a cylindrical portion 40. There are four fins 45 provided in the circumferential direction of the cylindrical portion 40. The fins 45 are plate-shaped members formed from the same material as the cylindrical portion 40. The fins 45 have a rectangular portion 45a and a triangular portion 45b. A part of the triangular portion 45b protrudes outward from the outer circumferential surface of the cylindrical portion 40. The triangular portion 45b has a sharp tip to facilitate penetration into the cancellous bone.

[0041] The cylindrical portion 40 has an opening 40a that connects the inside and outside of the cylinder. The width of the opening 40a is slightly wider than the width of the rectangular portion 45a of the fin 45. This allows the fin 45 to protrude from the inside to the outside of the cylinder through the opening 40a. The fin 45 may also have a stopper 45c that restricts the amount it protrudes from the outer circumferential surface of the cylindrical portion 40. The stopper 45c restricts the movement of the fin 45 by contacting the inner circumferential surface of the cylindrical portion 40.

[0042] Furthermore, as shown in Figure 4E, the amount of protrusion of the triangular portion 45b protruding from the outer surface of the cylindrical portion 40 may be changed by varying the shape of each fin 45. For example, the amount of protrusion of the triangular portion 45b may be reduced in areas close to the cortical bone, and increased in areas far from the cortical bone.

[0043] Figure 4F shows a plan view of the base plate 4f. The base plate 4f has a cylindrical portion 40 on which four fins 46 are provided. Each fin 46 has a rectangular portion 46a and a semicircular portion 46b. A portion of the semicircular portion 46b protrudes from the outer circumferential surface of the cylindrical portion 40.

[0044] Figure 4G shows a plan view of the base plate 4g. The base plate 4g has eight fins 45 on its cylindrical portion 40. The number of fins 45 is not particularly limited, but it is preferable to have three or more.

[0045] Figure 4H shows a plan view of the base plate 4h. The base plate 4h has four fins 47 provided on a cylindrical portion 40. The fins 47 extend in a direction inclined circumferentially with respect to the direction normal to the outer surface of the cylindrical portion 40.

[0046] Figure 4I shows a plan view of the base plate 4i. The fins 47 on the base plate 4i extend in a different direction than those on the base plate 4h shown in Figure 4H.

[0047] Figure 4J shows a side view of the base plate 4j. The base plate 4j has fins 48 that extend diagonally downward from the outer circumferential surface of the cylindrical portion 40.

[0048] The base plate 4k shown in Figure 4K has threads 49 provided on the outer circumferential surface of the cylindrical portion 40. The threads 49 are intermittently provided in the circumferential direction along the outer circumferential surface of the cylindrical portion 40. In addition, multiple rows of threads 49 are provided in the vertical direction. Note that the threads 49 may be provided intermittently in the circumferential direction along the outer circumferential surface of the cylindrical portion 40, or they may be provided around the entire circumference of the outer circumferential surface of the cylindrical portion 40. It is preferable that the lower surface of the threads 49 is inclined upward toward the tip to facilitate insertion of the base plate 4k into the tibia (see enlarged view).

[0049] The base plate 4m shown in Figure 4L has recesses 50 provided on the outer circumferential surface of the cylindrical portion 40. The recesses 50 are intermittently provided in the circumferential direction along the outer circumferential surface of the cylindrical portion 40. In addition, multiple rows of recesses 50 are provided in the vertical direction. Over time, cancellous bone penetrates into the recesses 50, suppressing the sinking of the base plate 4m. Note that the recesses 50 may be provided intermittently in the circumferential direction along the outer circumferential surface of the cylindrical portion 40, or they may be provided around the entire circumference of the outer circumferential surface of the cylindrical portion 40.

[0050] The cylindrical portion 40 shown in Figures 4C to 4L is cylindrical with openings at the top and bottom, but it may also be provided with a bottom portion 43 as shown in Figure 4A(b), or with a grid-like mesh portion 44 as shown in Figure 4A(c).

[0051] [Surgical Procedure] Figure 5 shows an example of the surgical procedure. In Figure 5(a), the tibia T has worn articular surface of the lateral condyle LC. First, a through hole extending in the anterior-posterior direction is formed below the articular surface of the lateral condyle LC using a drill or the like. Two through holes are formed side by side in the left-right direction. Next, as shown in Figure 5(b), the beam member 3 is driven into the through hole. Next, a round hole with a diameter corresponding to the diameter of the insert member 2 is formed in the lateral condyle LC above the beam member 3. Next, as shown in Figure 5(c), the base plate 4 is inserted into the round hole formed above the beam member 3. Finally, as shown in Figure 5(d), the insert member 2 is fitted onto the upper end of the base plate 4.

[0052] As described above, the artificial knee joint 1 of this embodiment includes an insert member 2 embedded in a part of the articular surface of the medial condyle MC or lateral condyle LC of the tibia T, The system comprises a beam member 3 positioned below the insert member 2 and having a length such that both ends are fixed to the cortical bone of the tibia T.

[0053] According to the artificial knee joint 1 of this embodiment, by embedding the insert member 2 in only a portion of the joint surface, the surface of the insert member 2 can be made to match the height and shape of the surrounding remaining joint surface, thereby making it possible to reproduce the height of the original joint surface. Furthermore, by reproducing the height of the original joint surface, the meniscus can also be preserved.

[0054] Furthermore, because the artificial knee joint 1 of this embodiment replaces only a portion of the joint, the surgery is easy, less invasive, and the risk of bleeding is reduced. It is possible to preserve the anterior cruciate ligament (ACL), and if damage to the ACL is found, it can be reconstructed at the same time. In addition, all ligaments, including the meniscus, can be preserved, and it is particularly possible to preserve the deep medial collateral ligament (dMCL), which was difficult to preserve in conventional methods.

[0055] The insert member 2 may be in contact with the beam member 3. With this configuration, the insert member 2 is reliably supported from below by the beam member 3.

[0056] The insert member 2 may not be in contact with the beam member 3. This configuration allows for some play between the insert member 2 and the beam member 3, thereby suppressing failure when a large load is applied.

[0057] Preferably, the outer edge portion of the insert member 2 adjacent to the meniscus is formed in an arc shape. This configuration prevents interference with the meniscus and preserves it.

[0058] The beam member 3 may be positioned only along the front-to-back direction. If the beam member 3 is positioned along the left-to-right direction, a large load applied to one of the inner granules MC or outer granules LC may adversely affect the other inner granule MC or outer granule LC via the beam member 3.

[0059] The artificial knee joint 1 of this embodiment may further include a cylindrical base plate 4 positioned between the insert member 2 and the beam member 3, and supporting the outer edge of the insert member 2. With this configuration, the insert member 2 is reliably supported from below by the base plate 4 and the beam member 3.

[0060] The base plate 4 may be in contact with the beam member 3. With this configuration, the base plate 4 is reliably supported from below by the beam member 3.

[0061] The base plate 4 may not be in contact with the beam member 3. With this configuration, some play can be provided between the base plate 4 and the beam member 3, allowing the base plate 4 to sink and the height of the insert member 2 to be appropriately adjusted.

[0062] The upper part of the base plate 4 may have an inclined surface that is inclined with respect to a plane perpendicular to the cylindrical axis. With this configuration, the height of the insert member 2 can be adjusted to match the height and shape of the actual articular surface of the tibia T by rotating the base plate 4 around the cylindrical axis.

[0063] The surface of the insert member 2a, which is embedded in the medial condyle MC of the tibia T, is preferably formed as a concave curved surface. Normally, the articular surface of the original medial condyle MC is a concave curved surface, so with this configuration, the surface of the insert member 2a connects smoothly with the surrounding original articular surface.

[0064] The surface of the insert member 2b, which is embedded in the lateral condyle LC of the tibia T, is preferably formed as a convex curved surface. Since the articular surface of the original lateral condyle LC is normally a convex curved surface, this configuration allows the surface of the insert member 2b to smoothly connect with the surrounding original articular surface.

[0065] It should be noted that the artificial knee joint 1 is not limited to the configuration of the embodiment described above, nor is it limited to the effects and benefits described above. Furthermore, it goes without saying that the artificial knee joint 1 can be modified in various ways without departing from the spirit of the present invention. For example, any configuration or method of the multiple embodiments described above may be arbitrarily adopted and combined, and furthermore, any one or more configurations or methods related to the various modification examples described below may be arbitrarily selected and adopted in the configurations or methods of the embodiments described above.

[0066] For example, Figure 6A shows an example in which insert members 2 are embedded in a portion of the articular surface of the medial condyle MC and the lateral condyle LC, respectively. Although the base plate 4 is not shown in this figure, it may be provided, and the same applies to the following figures.

[0067] Figure 6B shows an example where the insert member 2 is D-shaped in plan view. Figure 6C shows an example where the insert member 2 is semicircular in plan view. Figure 6D shows an example where the insert member 2 is elliptical in plan view.

[0068] Figure 6E shows an example in which a beam member 3 extending in the left-right direction is arranged in addition to a beam member 3 extending in the front-to-back direction.

[0069] Figure 6F shows an example where each insert member 2 is fitted with one beam member 3 extending in the front-to-back direction and one beam member 3 extending in the left-to-right direction. Figure 6G shows an example where each insert member 2 is fitted with one beam member 3 extending in the front-to-back direction and two beam members 3 extending in the left-to-right direction. Figure 6H shows an example where only three beam members 3 extending in the left-to-right direction are fitted.

[0070] Figure 7 shows a plan view and a side view of an insert member 2e according to another embodiment. The insert member 2e is supported from below by the beam member 3 without going through the base plate 4. Therefore, the insert member 2e is disc-shaped and does not have a stepped portion 20. The disc-shaped insert member 2e is provided with projections 21 on its outer circumferential surface. The projections 21 are intermittently provided in the circumferential direction along the outer circumferential surface of the insert member 2e. In addition, multiple rows of projections 21 are provided in the vertical direction. It is preferable that the lower surface of the projections 21 is inclined upward toward the tip to facilitate driving the insert member 2e into the tibia (see enlarged view).

[0071] Furthermore, it is also possible to use unicompartmental knee arthroplasty (UKA) for the medial condyle (MC) and artificial knee joint 1 only for the lateral condyle (LC). [Explanation of symbols]

[0072] 1. Artificial knee joint 2 Insert members 2a Insert member 2b Insert member 2c Insert Member 2d insert member 3 Beam members 3a Beam member 3b Beam member 3c Beam member 4 Base Plate 4a Base plate 4b Base plate 4c baseplate 4D base plate 4e base plate 4f Base Plate 4g base plate 4h base plate 4i base plate 4J base plate 4K baseplate 4m base plate 40 Cylindrical section 40a opening 43 Bottom 44 Mesh section 45 fins 46 Fins 47 Finn 48 fins 49 threads 50 recesses T tibia MC medial condyle LC lateral condyle

Claims

1. A base plate that supports the outer edge of an insert member embedded in a hole formed in a part of the articular surface of the medial or lateral condyle of the tibia, It comprises a cylindrical portion and a protruding portion that extends outward from the outer circumferential surface of the cylindrical portion, The cylindrical portion has an opening that connects the inside and outside of the cylinder, and the protruding portion is a base plate that protrudes through the opening.

2. A base plate that supports the outer edge of an insert member embedded in a hole formed in a part of the articular surface of the medial or lateral condyle of the tibia, It comprises a cylindrical portion and a protruding portion that extends outward from the outer circumferential surface of the cylindrical portion, The cylindrical portion has fitting holes and fitting grooves formed therein, into which two beam members having a square cross-section are fitted. The two beam members are arranged in a cross shape. The fitting hole and fitting groove are offset in the direction of the cylindrical axis of the cylindrical portion of the base plate.

3. A base plate that supports the outer edge of an insert member embedded in a hole formed in a part of the articular surface of the medial or lateral condyle of the tibia, It comprises a cylindrical portion and a protruding portion that extends outward from the outer circumferential surface of the cylindrical portion, A base plate having a cylindrical shape with a bottom, comprising the aforementioned cylindrical portion and a bottom.

4. A base plate that supports the outer edge of an insert member embedded in a hole formed in a part of the articular surface of the medial or lateral condyle of the tibia, It comprises a cylindrical portion and a protruding portion that extends outward from the outer circumferential surface of the cylindrical portion, A base plate in which a grid-like mesh section is formed at the lower opening of the cylindrical portion.

Images