Knee prosthesis

Abstract

The application provides a knee joint prosthesis, which comprises a femoral condyle, a gasket, a tibial platform, a tibial support arranged on the top of the tibial platform, a tibial stem arranged on the bottom of the tibial platform, a plurality of limiting wings arranged on the outer side of the tibial stem, a central column arranged through the inner part of the tibial stem, the central column penetrating an intercondylar box and leaving a movable gap between the central column and the inner wall of the intercondylar box, a rotating device, the rotating device comprising a ball head and an inner lining, the ball head being arranged on the tibial support, the inner lining being arranged between the semispherical recess of the gasket and the ball head, the inner surface of the inner lining being in spherical surface rotating cooperation with the outer surface of the ball head, the outer periphery of the inner lining being provided with a limiting block, the limiting block extending into a limiting groove and cooperating with the limiting groove. The technical scheme of the application effectively solves the technical problem that the rotating stress of the existing knee joint prosthesis is transmitted to the prosthesis-bone interface, thereby causing the wear of the gasket and the loosening of the prosthesis.

Description

Technical Field

[0001] This invention relates to the field of orthopedic implants, and in particular to a knee joint prosthesis. Background Technology

[0002] Total knee arthroplasty is an effective treatment for end-stage knee osteoarthritis, rheumatoid arthritis, and other diseases. A typical knee prosthesis consists of a femoral prosthesis, a tibial prosthesis, and a polyethylene liner placed between them. Based on whether the polyethylene liner can rotate relative to the tibial plateau, knee prostheses are mainly divided into fixed-plateau and rotating-plateau types. Fixed-plateau prostheses are widely used clinically due to their relatively simple structure, ease of intraoperative manipulation, and good initial stability. However, existing fixed-plateau prostheses still have several shortcomings in practical use. First, the femoral prosthesis and the polyethylene liner usually use a butterfly or circular-to-plane contact method, resulting in a small joint contact area and low fit, which easily leads to contact stress concentration and accelerates the wear of the polyethylene liner. Second, the polyethylene liner is usually fixed to the tibial plateau by a locking structure, and the liner and the tibial plateau cannot rotate relative to each other; that is, the prosthesis lacks rotational freedom.

[0003] During knee flexion and extension, an unavoidable rotational tendency exists between the femoral and tibial prostheses. For fixed-platform prostheses, because the polyethylene liner is fixed to the tibial plateau and cannot rotate, this rotational tendency cannot be released through relative movement between the liner and the tibial plateau; it can only be transmitted to the prosthesis-bone interface through the highly matched polyethylene liner. The resulting rotational stress easily leads to complications such as accelerated wear of the polyethylene liner and prosthesis loosening, affecting the long-term stability and lifespan of the prosthesis. Although rotating-platform prostheses can provide rotational freedom to some extent, they often have problems such as complex structure, risk of liner dislocation, and insufficient stability, making it difficult to fully meet clinical needs. Fixed-platform prostheses use a butterfly or circular contact method with a flat surface, resulting in a smaller joint contact area and lower fit. Furthermore, the polyethylene liner is fixed to the tibial plateau and cannot rotate. During knee flexion and extension, an unavoidable rotational tendency exists between the femoral and tibial prostheses. Because fixed-platform prostheses lack rotational freedom, this rotational stress is transmitted to the prosthesis-bone interface through the highly matched polyethylene liner, easily leading to complications such as accelerated liner wear and prosthesis loosening. Summary of the Invention

[0004] The purpose of this invention is to provide a knee joint prosthesis to solve the technical problem of existing knee joint prostheses where rotational stress is transmitted to the prosthesis-bone interface, leading to liner wear and prosthesis loosening.

[0005] To address the aforementioned technical problems, this invention provides a knee joint prosthesis, specifically comprising: a femoral condyle, the femoral condyle including: a fitting surface, the fitting surface being in close contact with the host bone; a fixation post, the fixation post protruding from the fitting surface for insertion and fixation to the distal end of the femur; a condylar surface, the condylar surface being located at the bottom of the femoral condyle; a spacer, the top of the spacer having a superior articular surface, the superior articular surface being curved and rotatably fitting with the condylar surface; an intercondylar box having a central portion of the spacer, the intercondylar box being a cavity penetrating the central portion of the spacer; and a hemispherical groove having a central portion of the central portion of the spacer, the hemispherical groove having multiple limiting grooves around its perimeter. The tibial plateau has a tibial support at its top and a tibial shaft at its bottom. Multiple limiting wings are located on the outer side of the tibial shaft. A central column runs through the interior of the tibial shaft, penetrating the intercondylar box and leaving a gap for movement between the central column and the inner wall of the intercondylar box. A rotating device includes a ball head and a liner. The ball head is positioned on the tibial support. The liner is located between the hemispherical groove of the gasket and the ball head, with the inner surface of the liner spherically engaging with the outer surface of the ball head. A limiting block is located on the outer periphery of the liner, extending into and engaging with a limiting groove.

[0006] Furthermore, the knee joint prosthesis also includes a disc spring, which is a disc spring assembly formed by stacking multiple disc-shaped spring plates. The disc spring assembly is sleeved on the central column and is located inside the tibial plateau. The top of the disc spring is fixedly connected to the ball head, and a buffer zone is formed between the pad and the tibial support.

[0007] Furthermore, the bottom of the pad is provided with a groove, which is an arc-shaped groove. The tibia support is provided with a slide rail, which is slidably set in the groove. The height of the slide rail is less than the depth of the groove.

[0008] Furthermore, both the slide rail and the slide groove are designed in an arc shape, with the center of the arc being the center of the ball head.

[0009] Furthermore, the knee joint prosthesis also includes a hinge, which includes an I-beam shaft fixedly mounted on the femoral condyle. A sleeve is rotatably mounted on the outer side of the I-beam shaft. A fixing tooth extending radially inward is provided on the inner wall of the top of the central column. An annular groove is provided on the outer periphery of the sleeve. The fixing tooth engages in the annular groove so that the sleeve and the central column are axially fixed.

[0010] Furthermore, the I-beam shaft and the fixed teeth are made of cobalt-chromium-molybdenum or titanium alloy, and the sleeve is made of highly cross-linked polyethylene.

[0011] Furthermore, the ball head is made of cobalt-chromium-molybdenum alloy, titanium alloy, or ceramic, while the inner lining is made of highly cross-linked polyethylene or ceramic.

[0012] Furthermore, the apposition surfaces of the femoral condyles and the tibial plateau are provided with porous coatings, hydroxyapatite coatings, or trabecular structures.

[0013] Furthermore, the superior articular surface includes a medial condylar surface and a lateral condylar surface, with the radius of curvature of the medial condylar surface being greater than that of the lateral condylar surface.

[0014] According to the technical solution of this invention, the femoral condyle includes: a fitting surface that is in close contact with the host bone; a fixation post protruding from the fitting surface for insertion and fixation to the distal end of the femur; a condylar surface located at the bottom of the femoral condyle; a superior articular surface provided at the top of the spacer, the superior articular surface being curved and rotatably fitting with the condylar surface; an intercondylar box provided in the middle of the spacer, the intercondylar box being a cavity penetrating the middle of the spacer; a hemispherical groove provided at the bottom of the spacer, with multiple limiting grooves provided around the hemispherical groove; and a tibialis plateau provided at the top. The prosthesis comprises a tibial plateau with a tibial shaft at its base. Multiple limiting wings are located on the outer side of the tibial shaft, and a central column runs through the interior of the tibial shaft, penetrating the intercondylar box and leaving a gap for movement between the central column and the inner wall of the intercondylar box. The rotating mechanism includes a ball head and a liner. The ball head is positioned on the tibial plateau. The liner is located between the hemispherical groove of the pad and the ball head, with the inner surface of the liner spherically engaging with the outer surface of the ball head. A limiting block is located on the outer periphery of the liner, extending into and engaging with a limiting groove. Through this design, relative rotational displacement can occur between the tibial plateau and the pad via the rotating mechanism. Furthermore, due to the hinge between the femoral condyle and the tibial plateau, this prosthesis maintains good stability while improving joint contact fit and providing appropriate rotational freedom. This reduces rotational stress transmission to the prosthesis-bone interface, lowers liner wear, and reduces the risk of prosthesis loosening. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A front view of the knee joint prosthesis is shown; Figure 2 The image shows a triaxial view of the femoral condyle; Figure 3 A cross-sectional view of the hinge is shown; Figure 4 The bottom and top views of the gasket are shown; Figure 5 A diagram showing the internal structure of a knee joint prosthesis is provided. Figure 6 A cross-sectional view of a knee joint prosthesis is shown; Figure 7 A cross-sectional view of the fixed tooth is shown; The above-mentioned figures include the following reference numerals: 10, femoral condyle; 101, caulking surface; 102, fixation post; 103, condylar surface; 20, gasket; 201, superior articular surface; 202, intercondylar box; 203, hemispherical groove; 204, limiting groove; 205, sliding groove; 30, tibial plateau; 301, limiting wing; 302, central post; 303, tibial support; 304, slide rail; 305, tibial shaft; 40, hinge; 401, I-beam; 402, sleeve; 403, fixing tooth; 50, rotating device; 501, liner; 502, limiting block; 503, ball head; 60, disc spring; 70, buffer zone. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0018] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Any specific values ​​in all examples shown and discussed herein should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0019] like Figure 1-3As shown, a knee joint prosthesis includes: a femoral condyle 10, a spacer 20, a tibial plateau 30, and a hinge 40. The spacer 20 is disposed between the femoral condyle 10 and the tibial plateau 30, and the femoral condyle and the tibial plateau are connected by the hinge 40. The femoral condyle 10 has fitting surfaces 101 on both sides of its top, which are fixed in close contact with the host bone. A fixation post 102 is disposed at the center of the top of the femoral condyle, protruding from the fitting surface. The fixation post 102 is used to fix the femoral condyle to the distal end of the femur. A condylar surface 103 is disposed at the bottom of the femoral condyle. The hinge 40 consists of an I-beam 401 and a sleeve 402. The I-beam 401 is disposed at the center of the bottom of the femoral condyle, and the sleeve 402 is sleeved on the outer side of the I-beam, allowing the sleeve 402 to rotate around the I-beam 401.

[0020] like Figure 4 As shown, the gasket 20 has an upper articular surface 201 at its top. The upper articular surface is curved and includes a medial condylar surface and a lateral condylar surface. The radius of curvature of the medial condylar surface is greater than that of the lateral condylar surface. The upper articular surface is rotatably fitted with the condylar surface 103. An intercondylar box 202 is provided in the middle of the gasket, which is a cavity penetrating the middle of the gasket. A hemispherical groove 203 is provided at the bottom of the gasket, and multiple limiting grooves 204 are provided around the hemispherical groove. A sliding groove 205 is also provided at the bottom of the gasket, which is an arc-shaped groove.

[0021] like Figure 5-6 As shown, a tibial platform 30 is provided on the top of the tibial platform, and a tibial support 303 is provided on the tibial support. A slide rail 304 is provided on the tibial support, and the slide rail is slidably provided in a slide groove 205. The height of the slide rail 304 is less than the depth of the slide groove 205. The tibial plateau 30 has a tibial shaft 305 at its bottom, multiple limiting wings 301 on its outer side, and a central pillar 302 penetrating through the interior of the tibial shaft, passing through the intercondylar box 202 and leaving a movable gap between the central pillar and the inner wall of the intercondylar box 202. A rotating device 50 includes a ball head 503 and an inner liner 501. The ball head 503 is mounted on the tibial support 303. The inner liner 501 is positioned between the hemispherical groove 203 of the gasket 20 and the ball head 503, with the inner surface of the inner liner spherically engaging with the outer surface of the ball head. A limiting block 502 is provided around the outer periphery of the inner liner 501, extending into a limiting groove 204 and engaging with and fixing it to the limiting groove 204. The slide rails and grooves are both arc-shaped, with the center of the arc being the center of the ball head.

[0022] With the above-mentioned design, after the knee prosthesis is implanted, the spacer 20 can be rotated by the rotating device 50. Compared with a fixed platform type prosthesis, by designing the spacer 20 as a movable pad that can rotate relative to the tibial plateau, a higher degree of fit is maintained between the femoral condyle 10 and the spacer 20. The axial rotation during knee flexion and extension mainly occurs between the femur and the tibial plateau, thereby releasing the inevitable rotational tendency between the femoral and tibial prostheses, reducing the transmission of rotational stress to the prosthesis-bone interface, and helping to reduce the risk of complications such as accelerated wear of the spacer 20 and prosthesis loosening. At the same time, this design can increase the joint contact area, reduce contact stress concentration, reduce wear on the dorsal side of the spacer, edge load and cold flow phenomenon, and enable the spacer to automatically align with the femoral prosthesis, improve the rolling-sliding and axial rotation kinematics of the knee joint, and make the postoperative knee joint movement closer to the physiological state. It can also compensate for the rotational alignment error of the tibial prosthesis to a certain extent, improve the alignment tolerance, and thus achieve a better balance between stability, mobility and low wear.

[0023] like Figure 1 , 5 As shown in Figure 6, in order to further improve the stability of the knee joint prosthesis, a disc spring 60 is also provided in the knee joint prosthesis. The disc spring is a disc spring group formed by stacking multiple disc-shaped spring plates. The disc spring group is sleeved on the central column 302. The disc spring is located inside the tibial plateau 30. The top of the disc spring is fixedly connected to the ball head 503. A buffer zone is formed between the pad 20 and the tibial support 303.

[0024] like Figure 7 As shown, the inner top wall of the central column 302 is provided with radially inwardly extending fixing teeth 403, and the outer periphery of the sleeve 402 is provided with an annular groove. The fixing teeth are inserted into the annular groove so that the sleeve and the central column are relatively fixed in the axial direction.

[0025] To further improve the fixation and wear resistance of the knee prosthesis, the I-beam and fixation teeth are made of cobalt-chromium-molybdenum or titanium alloy, and the sleeve is made of highly cross-linked polyethylene. The ball head is made of cobalt-chromium-molybdenum or titanium alloy or ceramic, and the liner is made of highly cross-linked polyethylene or ceramic. The patency surface of the femoral condyle and the surface of the tibial plateau are equipped with a porous coating, a hydroxyapatite coating, or a trabecular structure.

[0026] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0027] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0028] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A knee joint prosthesis, characterized in that, include: The femoral condyle includes: a patency surface that is in close contact with the host bone; a fixation post that protrudes from the patency surface for insertion and fixation to the distal end of the femur; and a condylar surface located at the bottom of the femoral condyle. The gasket has an upper articular surface at its top, which is curved and rotatably fits the aforementioned condylar surface; an intercondylar box is provided in the middle of the gasket, which is a cavity penetrating the middle of the gasket; and a hemispherical groove is provided at the bottom of the gasket, with multiple limiting grooves around the hemispherical groove. The tibial platform has a tibial support at its top and a tibial shaft at its bottom. Multiple limiting wings are provided on the outer side of the tibial shaft. A central column is provided through the interior of the tibial shaft. The central column passes through the aforementioned intercondylar box and has an movable gap between it and the inner wall of the intercondylar box. A rotating device, comprising a ball head and an inner liner, wherein the ball head is disposed on the tibial support; the inner liner is disposed between the hemispherical groove of the pad and the ball head, and the inner surface of the inner liner is spherically engaged with the outer surface of the ball head; a limiting block is provided on the outer periphery of the inner liner, the limiting block extending into the limiting groove and engaging with the limiting groove.

2. The knee joint prosthesis according to claim 1, characterized in that, The knee joint prosthesis also includes a disc spring, which is a disc spring assembly formed by stacking multiple disc-shaped spring plates. The disc spring assembly is sleeved on the central column. The disc spring is located inside the tibial plateau. The top of the disc spring is fixedly connected to the ball head. A buffer zone is formed between the pad and the tibial support.

3. The knee joint prosthesis according to claim 1, characterized in that, The bottom of the pad is also provided with a sliding groove, which is an arc-shaped groove. The tibia support is provided with a slide rail, which is slidably disposed in the aforementioned sliding groove. The height of the slide rail is less than the depth of the sliding groove.

4. The knee joint prosthesis according to claim 3, characterized in that, Both the slide rail and the slide groove are designed in an arc shape, with the center of the arc being the center of the ball head.

5. The knee joint prosthesis according to claim 1, characterized in that, The knee joint prosthesis also includes a hinge, which includes an I-beam shaft fixedly mounted on the femoral condyle. A sleeve is rotatably mounted on the outer side of the I-beam shaft. The inner top wall of the central column is provided with radially inwardly extending fixing teeth. The outer periphery of the sleeve is provided with an annular groove. The fixing teeth are engaged in the annular groove so that the sleeve and the central column are axially fixed.

6. The knee joint prosthesis according to claim 5, characterized in that, The I-beam and the fixed teeth are made of cobalt-chromium-molybdenum or titanium alloy, and the sleeve is made of highly cross-linked polyethylene.

7. The knee joint prosthesis according to claim 1, characterized in that, The ball head is made of cobalt-chromium-molybdenum alloy, titanium alloy, or ceramic, and the inner liner is made of highly cross-linked polyethylene or ceramic.

8. The knee joint prosthesis according to claim 1, characterized in that, The patency surface of the femoral condyle and the surface of the tibial plateau are provided with a porous coating, a hydroxyapatite coating, or a trabecular structure.

9. The knee joint prosthesis according to claim 1, characterized in that, The upper articular surface includes a medial condylar surface and a lateral condylar surface, wherein the radius of curvature of the medial condylar surface is greater than the radius of curvature of the lateral condylar surface.

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