CN212089847U - Knee joint prosthesis - Google Patents

Abstract

The utility model provides a knee joint prosthesis, include: a tibial plateau; the femoral condyle component is positioned above the tibial plateau and comprises a medial condyle articular surface and a lateral condyle articular surface, wherein a height difference H is formed between the medial condyle articular surface and the lateral condyle articular surface; the gasket part is positioned between the tibial plateau and the femoral condyle part, the gasket part comprises an inner side gasket matched with the inner condyle articular surface and an outer side gasket matched with the outer condyle articular surface, the position of the upper surface of the tibial plateau, corresponding to the outer side gasket, is provided with a first spherical convex surface, the outer side gasket is movably arranged on the tibial plateau, and the lower surface of the outer side gasket is provided with a first spherical concave surface matched with the first spherical convex surface. The technical scheme of the utility model the problem of the easy wearing and tearing of knee joint prosthesis among the correlation technique has been solved effectively.

Description

Knee joint prosthesis

Technical Field

The utility model relates to an orthopedic implant field particularly, relates to a knee joint prosthesis.

Background

The current artificial knee joint prostheses used for total knee replacement are mainly divided into femoral condylar components, spacer components and tibial plateau components, and some artificial knee joint prostheses also include patellar components. The basic form of the femoral condylar component has medial and lateral condylar articular surfaces and a patellar glide track articular surface. The shim component has two articular surfaces that respectively correspond to the medial and lateral condylar articular surfaces of the femoral condylar component to form a friction pair. The lower portion of the tibial plateau is a bone-engaging surface for seating on a bed of resected tibia bone, and the upper portion of the tibial plateau is a planar structure for supporting body loads transmitted from the spacer member. Depending on the severity of the patient's Knee joint destruction, femoral condylar Prostheses have also been designed with various additional structural forms, such as the Posterior Cruciate Retaining Knee prosthesis, the posteror crystalline-prosthetic Total Knee prosthetes (commonly referred to as CR-type), the bicondylar femoral condyles of which are integrally connected by a patellar slideway and which remain open posteriorly to accommodate the Posterior Cruciate ligament. The Posterior Stabilized Knee prosthesis Posterior Stabilized Total Knee Prostheses (generally called PS type) without retaining the Posterior cruciate ligament is provided with a limit cross beam at the back of the double condyles, and is matched with a central upright post of a tibial gasket to increase the stability of the prosthesis. Other designs, both semi-constrained and fully-constrained, maintain the stability of the implanted knee prosthesis by adding additional structure and components.

The above different kinds of knee joint prostheses basically keep the same in the mechanical design concept of the joint surface, that is, the osteotomy surface of the proximal tibia is perpendicular to the anatomical axis of the tibia, and the osteotomy surface of the distal femur is at an angle (acute lateral angle) of 84 ° to the anatomical axis of the femur. The joint line of the knee prosthesis formed after the operation is vertically penetrated by the lower limb force line from the middle, namely the joint line is vertical to the mechanical axis and has slight outward inclination with the gravity line, and the operation is the classic operation of knee replacement for many years. The inventor finds that the motion and stress state of the knee joint prosthesis in the prior art are greatly different from the motion and stress state of the physiological knee joint of the human body, thereby causing the wear of the knee joint prosthesis to be increased. The main points are as follows:

the human physiological knee joint line (i.e. the line connecting the far ends of the medial and lateral condyles of the knee joint or the line connecting the high points of the medial and lateral tibial plateaus) is perpendicular to the gravity line (i.e. the force line pointing to the center of the earth) or parallel to the horizontal plane, but in the design of the prior various knee joint prostheses, the joint line forms an inclination angle of about 3 degrees with the horizontal plane, so that the surface of the femoral condyle prosthesis, which is in contact with the tibial plateau gasket, can generate a transverse shearing force under the action of gravity, and the shearing force increases additional wear risk in the motion of the joint pair;

during the flexion and extension of the knee joint, the tibia can generate certain rotary motion relative to the femur, under the condition of a normal human physiological knee joint, the rotary motion rotates around an instantaneous central line vertical to the ground in a horizontal plane, but after the knee joint prosthesis operation, the rotary motion rotates around an instantaneous central line parallel to an anatomical axis of the tibia in an inclined plane with an included angle of 3 degrees with the horizontal plane, at the moment, the tensioning stress conditions of all ligaments around the inside and the outside, which participate in keeping the knee joint stable, are greatly different from those under the normal physiological condition, so that the gait and the motion proprioception of a patient feel abnormal during the flexion and extension actions, obvious sense of incongruity can be generated, and the abrasion of the medial or lateral prosthesis joint surface with larger stress can be aggravated.

When the knee joint is highly flexed, the shim of the knee joint prosthesis in the prior art cannot adjust the pitching angle, which causes the posterior condylar posterior edge of the femoral condylar prosthesis to frequently form edge contact with the shim, and even causes the posterior condylar posterior edge of the femoral condylar prosthesis to bite the shim, so that the service life of the knee joint prosthesis is shortened.

In the knee joint movement, the femoral condyle component slides and rotates forwards, backwards, leftwards and rightwards relative to the tibial plateau, although in the prior art, the tibial plateau gasket of the knee joint prosthesis can also generate some micro-movements, the tibial plateau gasket cannot follow the movement track of the femoral condyle in an all-around manner, and particularly, when the tibial plateau gasket rotates, the concave articular surface of the gasket which is originally well matched with the femoral prosthesis condyle surface is necessarily rolled or collided with the femoral prosthesis condyle side surface, so that the abrasion is accelerated.

SUMMERY OF THE UTILITY MODEL

The main object of the present invention is to provide a knee joint prosthesis to solve the problem of easy wear of knee joint prosthesis in the related art.

In order to achieve the above object, the present invention provides a knee joint prosthesis, comprising: a tibial plateau; the femoral condyle component is positioned above the tibial plateau and comprises a medial condyle articular surface and a lateral condyle articular surface, wherein a height difference H is formed between the medial condyle articular surface and the lateral condyle articular surface; a shim component located between the tibial plateau and the femoral condyle component.

Further, the pad component comprises a medial pad matched with the medial condyle articular surface and a lateral pad matched with the lateral condyle articular surface, the upper surface of the tibial plateau is provided with a first spherical convex surface corresponding to the position of the lateral pad, the lateral pad is movably arranged on the tibial plateau, and the lower surface of the lateral pad is provided with a first spherical concave surface matched with the first spherical convex surface.

Further, the height difference H is between 0.5mm and 5 mm.

Further, the lateral condylar articular surface has a second spherical convex surface and the spacer component has a second spherical concave surface that mates with the second spherical convex surface.

Further, the lateral condyle articular surface also has a first reducing convex curved surface.

Further, the medial condyle articular surface has a second reducing convex curved surface, and the gasket member has a first reducing concave curved surface matched with the second reducing convex curved surface.

Further, the upper surface of the tibial plateau has a first plane corresponding to the position of the medial condylar articular surface, and the lower surface of the medial insert has a second plane that mates with the first plane; alternatively, the upper surface of the tibial plateau has a third spherical convex surface at a location corresponding to the medial condylar articular surface, and the lower surface of the medial insert has a third spherical concave surface that mates with the third spherical convex surface.

Further, the tibial platform comprises a platform body, a peripheral side wall arranged at the circumferential edge of the platform body, and a first inner side wall and a second inner side wall which are arranged inside the peripheral side wall, the outer side gasket is arranged in a first space formed by the first inner side wall and the peripheral side wall, the inner side gasket is arranged in a second space formed by the second inner side wall and the peripheral side wall, the first inner side wall protrudes towards the outer side gasket, and the second inner side wall protrudes towards the inner side gasket.

Furthermore, the tibial platform comprises a platform body, a peripheral side wall arranged at the circumferential edge of the platform body, and a first inner side wall and a second inner side wall which are arranged inside the peripheral side wall, the outer side gasket is movably arranged in a first space enclosed by the first inner side wall and the peripheral side wall, and the inner side gasket is movably arranged in a second space enclosed by the second inner side wall and the peripheral side wall.

Further, the first space has a size greater than a size of the lateral insert to allow the lateral insert to slide and/or rotate relative to the tibial plateau and the second space has a size greater than a size of the medial insert to allow the medial insert to slide and/or rotate relative to the tibial plateau.

Further, the medial pad is fixedly disposed on the tibial plateau, and the pad member further includes a post disposed on the medial pad.

Furthermore, the femoral condyle component also comprises a patella slideway joint surface connected between the medial condyle joint surface and the lateral condyle joint surface and a limiting cross beam connected between the posterior condyle of the medial condyle joint surface and the posterior condyle of the lateral condyle joint surface, and the stand column can limit the limiting cross beam.

Further, a shaft is arranged on the tibial platform, an inner hole is formed in the stand column, and the shaft is inserted into the inner hole.

Furthermore, the tibial platform also comprises an intramedullary rod arranged below the platform body, and an included angle alpha is formed between a perpendicular line perpendicular to the upper surface of the tibial platform and the intramedullary rod.

The utility model also provides a knee joint prosthesis, include: a tibial plateau; a femoral condyle component located above the tibial plateau, the femoral condyle component comprising a medial condyle articular surface and a lateral condyle articular surface; the gasket part is positioned between the tibial plateau and the femoral condyle part, the gasket part comprises an inner side gasket matched with the inner condyle articular surface and an outer side gasket matched with the outer condyle articular surface, the position of the upper surface of the tibial plateau, corresponding to the outer side gasket, is provided with a first spherical convex surface, the outer side gasket is movably arranged on the tibial plateau, and the lower surface of the outer side gasket is provided with a first spherical concave surface matched with the first spherical convex surface.

Use the technical scheme of the utility model, tibial plateau sets up on the shin bone after cutting the bone, and thighbone condyle component sets up on the thighbone after cutting the bone, and the gasket part sets up between tibial plateau and thighbone condyle component. The femoral condyle component includes a medial condyle articular surface and a lateral condyle articular surface. Both the medial and lateral condylar articular surfaces are in contact with the shim component. The difference in height between the distal-most point of the medial condyle and the distal-most point of the lateral condyle is H when the patient is in the upright position and the flexed position, and the distal-most point of the medial condyle is slightly lower than the distal-most point of the lateral condyle when viewed in the coronal view. The height difference H is set so that the distal medial-lateral condyle distal-most point connecting line of the femur, i.e. the joint line, is parallel to the horizontal plane and is no longer perpendicular to the tibial anatomical axis. The arrangement mode can effectively avoid the transverse shear stress generated by the contact surfaces between the femoral condyle component and the gasket component and between the gasket component and the tibial plateau under the action of gravity. Therefore, the technical scheme of the application effectively solves the problem that the knee joint prosthesis in the related art is easy to wear due to shear stress. Meanwhile, after the technical scheme of the application is applied, the rotary motion between the tibia and the femur in the flexion and extension process of the knee joint of the patient rotates around the instantaneous central line vertical to the ground in the approximately horizontal plane, so that the patient has normal gait and motion feeling. When the knee joint is highly flexed, the gasket component can slide backwards along the spherical convex surface on the upper surface of the tibial plateau and then tilt backwards, so that the rear edge of the femoral condyle prosthesis and the gasket are prevented from forming side contact and biting the gasket. And in the knee joint movement, the gasket component can slide and rotate along the spherical convex surface or the plane of the upper surface of the tibial plateau in all directions along with the femoral condyle component, so that the contact surface between the gasket component and the femoral condyle component is well matched, and the side surface is prevented from rolling or colliding.

Drawings

The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 shows an exploded structural view of a first embodiment of a knee joint prosthesis according to the invention;

FIG. 2 is another perspective exploded view of the knee prosthesis of FIG. 1;

FIG. 3 illustrates a partial structural cross-sectional view of the knee prosthesis of FIG. 2;

FIG. 4a shows a schematic view of the movement of a shim component of the knee joint prosthesis of FIG. 1;

FIG. 4b shows a schematic top view of the shim member of FIG. 4 a;

FIG. 5 illustrates a front view of a femoral condyle component of the knee prosthesis of FIG. 1;

FIG. 6 shows a schematic cross-sectional view of the femoral condyle component A-A of FIG. 5;

FIG. 7 shows a cross-sectional view of the femoral condyle component B-B of FIG. 5;

FIG. 8 shows a curvilinear schematic of the medial condyle articular surface of FIG. 6;

FIG. 9 shows a curvilinear schematic of the lateral condylar articular surface of FIG. 7;

FIG. 10 illustrates a side schematic view of a tibial plateau of the knee prosthesis of FIG. 1;

FIG. 11 illustrates a cross-sectional view of the knee prosthesis of FIG. 1 in comparison to the prior art;

FIG. 12 shows a cross-sectional view of the knee prosthesis of FIG. 1 in another state with the prior art;

FIG. 13 is an exploded schematic view of the knee prosthesis of FIG. 1 and a prior art assembly;

FIG. 14 is an exploded view of the knee prosthesis of FIG. 11 from another perspective of the prior art;

FIG. 15 is a schematic representation of the knee prosthesis of FIG. 11 in a kinematic state with respect to the prior art;

fig. 16 shows an exploded structural view of a second embodiment of a knee joint prosthesis according to the present invention;

FIG. 17 illustrates a partial structural cross-sectional view of the knee prosthesis of FIG. 16;

fig. 18 shows an exploded structural view of a third embodiment of a knee joint prosthesis according to the present invention; and

FIG. 19 illustrates a partial structural cross-sectional view of the knee prosthesis of FIG. 18.

Wherein the figures include the following reference numerals:

10. a tibial plateau; 11. a first spherical convex surface; 12. a first plane; 13. a third spherical convex surface; 14. a platform body; 15. a peripheral side wall; 161. a first inner sidewall; 162. a second inner sidewall; 17. a shaft; 18. an intramedullary rod; 20. a femoral condyle component; 21. the medial condyle articular surface; 211. a second variable diameter convex curved surface; 22. the lateral condylar articular surface; 221. a second spherical convex surface; 222. a first variable diameter convex curved surface; 23. patellar slideway articular surface; 24. a limiting cross beam; 30. a gasket member; 31. a first spherical concave surface; 32. a second plane; 33. a third spherical concave surface; 34. an inner side pad; 35. an outer spacer; 36. a column; 361. an inner bore; 37. a first variable diameter concave curved surface; 38. a second spherical concave surface.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

Unless specifically stated otherwise, the relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

The inventor finds out the specific cause of abrasion in the prior art after experiments. In the prior art, the joint line of the knee joint prosthesis forms an angle of 3 degrees with the horizontal plane, and the surfaces of the femoral condyle component in contact with the shim component and the shim component with the tibial plateau generate a transverse shear force under the action of gravity, which increases the risk of additional wear during the movement of the knee joint prosthesis.

Meanwhile, in the flexion and extension process of the knee joint, the tibia generates certain rotary motion relative to the femur, under the normal physiological condition, the rotary motion rotates around an instantaneous central line vertical to the ground in a horizontal plane, but the rotary motion after operation is changed into the rotary motion around the instantaneous central line parallel to the anatomical axis of the tibia in an inclined plane with an included angle of 3 degrees with the horizontal plane, at the moment, the tensioning stress conditions of all internal and external peripheral ligaments participating in keeping the knee joint stable are greatly different from those under the normal physiological condition before operation, so that the gait and motion of a patient are abnormal in the flexion and extension action, obvious discomfort can be generated, and the abrasion of the medial or lateral prosthesis joint surface with larger stress can be aggravated.

When the knee joint is highly flexed, the pad of the knee joint prosthesis in the prior art cannot adjust the pitching angle, so that the posterior condylar rear edge of the femoral condylar prosthesis often forms edge contact with the pad and even bites the pad, and the service life of the knee joint prosthesis is shortened due to the condition.

The femoral condyle can slide and rotate in the front-back and left-right directions relative to a tibial plateau in knee joint movement, although a gasket of a knee joint prosthesis in the prior art can also generate a little micromotion, the gasket cannot follow the running track of the femoral condyle in an all-around manner, particularly when the gasket rotates, the gasket is originally well matched with a concave joint surface of the femoral prosthesis condyle surface, and along with the rotation, the side surface of the femoral prosthesis condyle and the gasket can generate rolling or collision, so that the abrasion is accelerated.

The inventors performed relevant analyses on human femoral condyles, knee joints, and tibia. At present, the more consistent view in the medical field is that the lower limb mechanics of the human body have three pairs, namely a gravity line, a mechanical axis and an anatomical axis. In addition, there is a significant marking line, namely the joint line (i.e. the line connecting the distal ends of the medial and lateral condyles of the knee joint or the line connecting the high points of the medial and lateral plateaus of the force line of the lower limb of the tibia). The gravity line is the line of force directed vertically through the center of gravity of the body to the center of the earth (parallel to the vertical line formed by the gravity of the earth), and the mechanical axis (also called mechanical axis) is the line of force from the center of the femoral head through the center of the knee joint to the center of the ankle joint. The anatomical axis, as viewed from the coronal plane, may be understood to approximate the midline of the femoral and tibial diaphysis. The "approximation" is due to the fact that the femoral diaphyseal axis is not a straight line when viewed in three dimensions. The joint line is usually in a nearly horizontal position, i.e. perpendicular to the plumb line. Under normal physiological conditions, when a human body stands, a connecting line of a femoral head center-knee joint center-ankle joint center is in the same straight line, the straight line is a mechanical axis or a mechanical axis of a lower limb, and an included angle between the mechanical axis and a gravity line is 3 degrees of outward inclination on average. The average included angle between the femoral anatomical axis of the femoral shaft and the mechanical axis at the center of the knee joint is 6 degrees of outward inclination, and the average included angle between the tibial anatomical axis and the gravity line is 3 degrees of outward inclination (the tibial anatomical axis is coincided with the mechanical axis of the lower limb under the normal physiological condition). The tibia angle is an outward included angle formed by the anatomical axis of the femur and the anatomical axis of the tibia in the center of the knee joint, the included angle is generally 174 degrees on average, and the average included angle between the anatomical axis of the femur and the gravity line is measured and calculated to be 9 degrees.

Based on the foregoing, in the present application, there is a height difference H between the medial and lateral condylar articular surfaces, i.e., the distal-most point of the medial condylar articular surface is slightly lower than the distal-most point of the lateral condylar articular surface when viewed in coronal view. In this way, when the knee joint prosthesis is implanted, the tibial osteotomy surface is osteotomy in parallel with the horizontal plane. Therefore, the joint line of the knee joint prosthesis after operation can be parallel to the horizontal plane, and the physiological included angle between the femur dissection shaft and the mechanical axis can not be influenced.

As shown in fig. 1 to 5, in a first embodiment, a knee joint prosthesis includes: a tibial plateau 10, a femoral condyle component 20, and a shim component 30. The femoral condyle component 20 is located above the tibial plateau 10, and the femoral condyle component 20 includes a medial condyle articular surface 21 and a lateral condyle articular surface 22, wherein the medial condyle articular surface 21 and the lateral condyle articular surface 22 have a height difference H therebetween. The shim component 30 is located between the tibial plateau 10 and the femoral condyle component 20.

Use the technical scheme of the utility model, tibial plateau 10 sets up on the shin bone after cutting the bone, and thighbone condyle component 20 sets up on the thighbone after cutting the bone, and gasket component 30 sets up between tibial plateau 10 and thighbone condyle component 20. The femoral condyle component 20 includes a medial condyle articular surface 21 and a lateral condyle articular surface 22. Both the medial condyle articular surface 21 and the lateral condyle articular surface 22 are in contact with the shim component 30. The difference in height between the distal-most point of the medial condyle articular surface 21 and the distal-most point of the lateral condyle articular surface 22 is H, i.e., the distal-most point of the medial condyle articular surface 21 is slightly lower than the distal-most point of the medial condyle articular surface 21 of the lateral condyle articular surface 22 and slightly lower than the distal-most point of the lateral condyle articular surface 22 when the patient is in the upright position and the flexed position. The height difference H is such that the joint line formed by the line connecting the distal-most point of the medial condyle articular surface 21 and the distal-most point of the lateral condyle articular surface 22 will, in use, no longer be perpendicular to the tibial anatomical axis but will be parallel to the horizontal plane. The above arrangement effectively avoids the lateral shear stresses that occur under the force of gravity on the surfaces of the femoral condyle component 20 in contact with the shim component 30 and the shim component 30 in contact with the tibial plateau 10. Therefore, the technical scheme of the application effectively solves the problem that the knee joint prosthesis in the related art is easy to wear due to shear stress. Meanwhile, after the technical scheme of the application is applied, the rotary motion between the tibia and the femur in the flexion and extension process of the knee joint of the patient rotates around the instantaneous central line vertical to the ground in the approximately horizontal plane, so that the patient has normal gait and motion feeling.

When the knee joint is in the upright position and the bent position, the farthest point of the medial condyle joint surface and the farthest point of the lateral condyle joint surface of the femoral condyle component have a height difference H, namely, the farthest point of the medial condyle joint surface is reduced by 0.5mm to 5mm than the farthest point of the lateral condyle joint surface so as to conform to the anatomical morphology of the femoral condyle of the human body. This feature continues from the distal-most point of the condylar articular surfaces to the posterior condyles, with the specific height differences being selected based on the specific data of the different patients.

The inner surface of the femoral condyle component 20, which is in contact with the femoral side osteotomy surface, is a femoral condyle osseointegration surface which is attached to the femoral side osteotomy surface in the operation and is integrated with the physiological bone of the patient in the future rehabilitation process through the bonding of bone cement or the connection of the rough surface and the porous structure surface of the osseointegration surface so as to provide the long-term stability of the prosthesis.

The femoral condyle component 20, the shim component 30 and the tibial plateau 10 are generally made of medical metal materials (cobalt alloy, titanium and titanium alloy, tantalum and tantalum alloy, magnesium alloy, etc.), medical ceramic materials (alumina ceramic, zirconia ceramic, silicon carbide ceramic, silicon nitride ceramic, etc.), and polymer materials.

The inventors have discovered that the knee joint can be seen in its anatomical configuration as a tibiofemoral joint consisting of the medial and lateral condyles at the distal femur with the medial and lateral platforms and menisci at the proximal tibia, respectively. The joint surface on the outer side of the tibial plateau is a bowl-shaped concave surface, and the convex external condyle joint surface of the femur and the concave external condyle joint surface of the tibial plateau are matched with each other, so that the joint pair on the outer side of the knee joint can flexibly do flexion and extension activities on the sagittal plane. The concavity of the medial tibial plateau facet is somewhat like the wide pelvic region enclosed by the meniscus, with anterior 1/3 being a gradually ascending concavity and posterior 2/3 being a gradually descending concavity, and the medial tibial plateau facet joint not maintaining a full flexion-extension motion from start to finish when it is associated with the medial femoral condyle, but rather allowing some degree of anterior-posterior sliding of the medial femoral condyle and rolling with multiple instantaneous centers of motion.

Based on the above studies, the present embodiment makes the following improvements to the prior art:

in one embodiment, as shown in fig. 1-9, the lateral condylar articular surface 22 has a second spherical convex surface 221 and the lateral shim 35 has a second spherical concave surface 38 that mates with the second spherical convex surface 221. The second spherical convex surface 221 is in contact with the second spherical concave surface 38, the second spherical convex surface 221 can slide and rotate on the second spherical concave surface 38, and the second spherical convex surface 221 and the second spherical concave surface 38 can form good mutual matching, so that the sliding and rotating of the second spherical convex surface 221 can be more stable.

In a first embodiment, as shown in FIGS. 2, 3 and 9, the lateral condylar articular surface 22 further has a first convexly tapered surface 222. The first convexly tapered surface 222 is connected to the second convexly spherical surface 221 to allow the lateral condylar articular surface 22 to slide with a greater amount of space. Also, the first tapered convex surface 222 can provide restraint to the patient's patella and the lateral side of the patellar ligament.

Fig. 6 and 7 are sectional views of fig. 5 taken along the line a-a and the line B-B, respectively. Fig. 6 shows primarily the contour of the medial condyle articular surface 21 and fig. 7 shows primarily the contour of the lateral condyle articular surface 22. Fig. 8 shows the contour of the medial condyle articular surface 21 and fig. 9 shows the contour of the lateral condyle articular surface 22. As shown in FIG. 9, for the contour of the lateral condylar articular surface 22, one portion corresponds to the second spherical convex surface 221 and the other portion corresponds to the first variable diameter convex surface 222. The radius of the arc corresponding to the second spherical convex surface 221 is SR0, and the contour corresponding to the first variable diameter convex curved surface 222 includes four arc segments, which have the radii of R1, R2, R3 and R4. Wherein, R1 indicates that the position is an inward concave arc, and the remaining arcs R2, R3 and R4 are convex arcs. In FIG. 9, the size relationship between SR0-R4 is shown and adjusted according to practical situations. As shown in fig. 8, the contour line corresponding to the second reducing convex curved surface 211 also includes four arc lines, and the radii of the four arc lines are R5, R6, R7 and R8 in sequence. These arcs are convex arcs. In FIG. 8, the dimension relationships labeled R5-R9 can be adjusted according to actual conditions. Of course, as a practical embodiment, for the contour line of the lateral condylar articular surface 22, the contour line corresponding to the first convexly tapered surface 222 may be a two-segment, three-segment, or five-segment or more arc line, or other curve, as long as the smooth and stable fit between the first convexly tapered surface 222 and the lateral shim 35 is satisfied. Similarly, for the contour line of the medial condyle articular surface 21, the contour line corresponding to the second reducing convex curved surface 211 may be two, three, or more than five arcs, or other curves, as long as the smooth and stable fit between the second reducing convex curved surface 211 and the medial pad 34 is satisfied.

In one embodiment, as shown in FIGS. 1-3, the medial condyle articular surface 21 has a second convexly tapered surface 211 and the medial pad 34 has a first concavely tapered surface 37 that mates with the second convexly tapered surface 211. When the knee joint is in the upright position, the second reducing convex curved surface 211 is matched with the first reducing concave curved surface 37 to provide the knee joint with stability, when the knee joint starts to bend, the second reducing convex curved surface 211 and the first reducing concave curved surface 37 form partial surface contact or even line contact to allow a certain sliding or rotating displacement between the femoral condyle component 20 and the gasket component 30, and the upper front half part of the medial condyle joint surface 21 is a convex variable-diameter curved surface and is in smooth transition with the adjacent patella slideway joint surface 23 so as to provide constraint on the inner sides of the patella and the patella ligament. The medial condylar articular surface 21 of the femoral condylar component 20 is a convex continuous variable diameter surface from its anterior inferior half to its posterior condyles that fits in contact with a first concave tapered concave surface 37 of the upper surface of the medial pad 34 of the pad component 30. The second reducing convex curved surface 211 is matched with the first reducing concave curved surface 37, so that the sliding and the rotation of the medial condyle articular surface 21 are more stable, and a better using effect is provided for a patient.

As shown in fig. 1-3, in one embodiment, the pad member 30 includes a medial pad 34 engaged with the medial condyle articular surface 21 and a lateral pad 35 engaged with the lateral condyle articular surface 22, the upper surface of the tibial plateau 10 has a first spherical convex surface 11 at a position corresponding to the lateral pad 35, the lateral pad 35 is movably disposed on the tibial plateau 10, and the lower surface of the lateral pad 35 has a first spherical concave surface 31 engaged with the first spherical convex surface 11. The first spherical convex surface 11 and the first spherical concave surface 31 can be mutually matched, and the first spherical concave surface 31 can slide and rotate on the first spherical convex surface 11. When the knee joint prosthesis is in the flexion position, the lateral condyle articular surface 22 can always keep a larger contact area with the lateral shim 35, so that the flexion stability is better, and the service lives of the lateral condyle articular surface 22 and the shim part 30 can be prolonged.

As shown in fig. 1-3, in one embodiment, the upper surface of the tibial plateau 10 has a first flat 12 at a location corresponding to the medial condylar articular surface 21, and the lower surface of the medial insert 34 has a second flat 32 that mates with the first flat 12. The first plane 12 fits with the second plane 32, and the second plane 32 can move or rotate relative to the first plane 12 to adapt to the movement of the medial condyle joint surface 21 relative to the pad component 30, so that the femoral condyle component 20 has a movement effect closer to that of a physiological knee joint, and a better use experience is brought to a patient.

As shown in FIGS. 1-3, in one embodiment, the shim component 30 includes a medial shim 34 that mates with the medial condyle articular surface 21 and a lateral shim 35 that mates with the lateral condyle articular surface 22. The inner pad 34 and the outer pad 35 are separated, the inner pad 34 and the outer pad 35 both have own motion modes, and the separated arrangement can effectively avoid the mutual restriction and interference of the inner pad 34 and the outer pad 35, so that the knee joint prosthesis has the motion effect more in line with the physiological knee joint of the human body. When the knee prosthesis is flexed to a maximum angle, the lateral insert 35 moves to the posterior edge of the tibial plateau 10, and the concave spherical surface of the lower surface of the lateral insert 35 and the convex spherical surface of the upper surface of the lateral tibial plateau still keep a good fit and the lateral insert 35 generates a backward tilt angle, which prevents the posterior edge of the femoral condyle component 20 from contacting and biting the insert component 30. Of course, the inner pad 34 and the outer pad 35 may be connected together or integrally formed as a feasible embodiment. At this time, it should be noted that, considering the difference of the movement between the inner pad 34 and the outer pad 35, the two pads need to be flexibly connected to avoid mutual influence. In this embodiment, during the knee joint movement, the tibial platform 10 and the shim member 30 slide and rotate in all directions along with the femoral condylar component 20, and the shim member 30 fits well with the surface of the femoral condylar component 20 to avoid rolling or collision. Meanwhile, when the knee joint is highly flexed, the rear edge of the posterior condyle and the gasket part do not form edge contact any more, so that the biting phenomenon is avoided.

In an embodiment not shown in the figures, the medial pad may also be of unitary construction with the lateral pad, with the construction of the pad being specifically selected according to the patient's condition.

As shown in fig. 1 to 4b, in the first embodiment, the tibial platform 10 includes a platform body 14, a peripheral side wall 15 disposed at a circumferential edge of the platform body 14, and a first inner side wall 161 and a second inner side wall 162 disposed inside the peripheral side wall 15, the inner spacer 34 is disposed in a second space surrounded by the second inner side wall 162 and the peripheral side wall 15, the outer spacer 35 is disposed in a first space surrounded by the first inner side wall 161 and the peripheral side wall 15, the second inner side wall 162 protrudes toward the inner spacer 34, and the first inner side wall 161 protrudes toward the outer spacer 35. The peripheral sidewall 15 cooperates with the first inner sidewall 161 and the second inner sidewall 162 to form a first space and a second space. The peripheral side wall 15, the first inner side wall 161 and the second inner side wall 162 are simple in structure and easy to form. The first inner sidewall 161 and the second inner sidewall 162 are outwardly convex arcs, so that the first inner sidewall 161 and the second inner sidewall 162 can provide a moving space for the lateral pad 35 and the medial pad 34 to rotate around the instant center with the femoral condyle component 20 to avoid collision between the sidewalls and the pads. The peripheral side wall 15 cooperates with the first inner side wall 161 and the second inner side wall 162 to prevent the spacer member 30 from being dislocated.

As shown in fig. 1, 4a, 4b, and 11 to 15, in a first embodiment, the tibial platform 10 includes a platform body 14, a peripheral side wall 15 disposed at a circumferential edge of the platform body 14, and a first inner side wall 161 and a second inner side wall 162 disposed inside the peripheral side wall 15, the inner pad 34 is movably disposed in a second space surrounded by the second inner side wall 162 and the peripheral side wall 15, and the outer pad 35 is movably disposed in a first space surrounded by the first inner side wall 161 and the peripheral side wall 15. The first space and the second space respectively limit the outer pad 35 and the inner pad 34, and prevent the inner pad 34 and the outer pad 35 from generating excessive movement, which leads to the damage of the knee joint prosthesis.

As shown in fig. 4a and 4b, in the first embodiment, the first space has a size greater than that of the lateral insert 35 to allow the lateral insert 35 to slide and/or rotate relative to the tibial plateau 10, and the second space has a size greater than that of the medial insert 34 to allow the medial insert 34 to slide and/or rotate relative to the tibial plateau 10. The sizes of the second space and the first space are respectively larger than the sizes of the inner side pad 34 and the outer side pad 35, so that the inner side pad 34 and the outer side pad 35 respectively have moving spaces in the second space and the first space, and further the pad component 30 has a larger moving space, and therefore, the performance of the knee joint prosthesis is effectively improved.

As shown in fig. 1, 10, 12 and 13, in a first embodiment, the tibial plateau 10 further includes an intramedullary rod 18 disposed below the plateau body 14, and a perpendicular line perpendicular to the upper surface of the tibial plateau 10 forms an angle α with the intramedullary rod 18. The average included angle between the femoral anatomical axis and the gravity line is 9 degrees, the average included angle between the tibial anatomical axis and the gravity line is 3 degrees, but the joint line of the knee joint (namely the connecting line of the far ends of the inner and outer condyles or the connecting line of the high points of the inner and outer platforms of the tibia) is nearly horizontal in the normal physiological state. The reason for the horizontal line is that the medial condyle of the femur is longer than the lateral condyle in anatomy, so that the included angle (lateral acute angle) between the connecting line of the distal end of the medial condyle and the distal end of the femoral anatomy shaft at the coronal position is about 81 degrees, and the included angle (medial acute angle) between the connecting line of the medial plateau and the lateral plateau of the tibia and the tibial anatomy shaft is about 87 degrees. When a certain relative rotation is generated between the femoral condyle and the tibial plateau in the flexion-extension action, the rotation surface is in the horizontal plane, and the instantaneous rotation center line is a plumb line. The angle alpha is thus set between 1 and 5 degrees, preferably 3 degrees. Through the setting of above-mentioned contained angle alpha make patient's postoperative platform body 14 keep parallel with the horizontal plane, can avoid producing shear stress between gasket part 30 and tibial plateau 10 and produce shear stress between tibial plateau 10 and the shin bone effectively, consequently this knee joint prosthesis has better result of use to patient's use experience has been promoted effectively.

In a second embodiment, shown in fig. 16, the medial insert 34 is fixedly disposed on the tibial plateau 10, and the insert member 30 further includes a post 36 disposed on the medial insert 34. The post 36 can replace the cruciate ligament to limit the forward and backward movement of the femoral condyle, and the structural strength of the post 36 is good.

As shown in fig. 16 and 17, in the second embodiment, the femoral condyle component 20 further comprises a patellar slideway articular surface 23 connected between the medial condyle articular surface 21 and the lateral condyle articular surface 22 and a limit beam 24 connected between the posterior condyle of the medial condyle articular surface 21 and the posterior condyle of the lateral condyle articular surface 22, and the post 36 can limit the limit beam 24. The upright post 36 is matched with the limit cross beam 24, and the upright post 36 can move in the limit cross beam 24, so that the knee joint prosthesis can be effectively prevented from excessively advancing.

As shown in fig. 16 and 17, in the second embodiment, the shaft 17 is disposed on the tibial platform 10, the inner hole 361 is disposed in the post 36, and the shaft 17 is inserted into the inner hole 361. The inner pad 34 is a fixed pad, and the lower surface of the fixed pad is a flat surface. The inner hole 361 is matched with the shaft 17 in a nesting mode, and the mechanical strength of the upright post 36 can be enhanced. Column 36 can rotate a little about axis 17, and then spacer component 30 can rotate a little about axis 17, makes the knee joint prosthesis have more active position, can prevent simultaneously that spacer component 30 and tibial plateau 10 from taking place to gnaw the phenomenon and can carry out spacing to spacing crossbeam 24.

In a third embodiment, as shown in figures 18 and 19, the upper surface of the tibial plateau 10 has a third spherical convex surface 13 at a location corresponding to the medial condylar articular surface 21, and the lower surface of the shim member 30 has a third spherical concave surface 33 that mates with the third spherical convex surface 13. The third spherical convex surface 13 and the third spherical convex surface 13 are matched with each other, and further, the embodiment provides four pairs of spherical friction pairs. Therefore, the design can ensure that the knee joint prosthesis obtains larger joint mobility and can ensure that the knee joint prosthesis is reliably and stably in the whole process from the vertical position to the flexion position, and further the sliding or moving effect of the femoral condyle component 20 is better, thereby effectively improving the performance of the knee joint prosthesis.

The utility model also provides a knee joint prosthesis, the embodiment of the knee joint prosthesis according to the application includes: a tibial plateau 10, a femoral condyle component 20, and a shim component 30. Wherein the femoral condyle component 20 is located above the tibial plateau 10, the femoral condyle component 20 includes a medial condyle articular surface 21 and a lateral condyle articular surface 22. The shim component 30 is positioned between the tibial plateau 10 and the femoral condylar component 20, the shim component 30 includes a medial shim 34 cooperating with the medial condylar articular surface 21 and a lateral shim 35 cooperating with the lateral condylar articular surface 22, the upper surface of the tibial plateau 10 has a first spherical convex surface 11 corresponding to the position of the lateral shim 35, the lateral shim 35 is movably disposed on the tibial plateau 10, and the lower surface of the lateral shim 35 has a first spherical concave surface 31 cooperating with the first spherical convex surface 11. In this embodiment, the difference from the above-described embodiments is that there is no height difference between the medial and lateral condylar articular surfaces of this embodiment.

In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the orientation words such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" etc. are usually based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplification of description, and in the case of not making a contrary explanation, these orientation words do not indicate and 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 interpreted as limiting the scope of the present invention; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and if not stated otherwise, the terms have no special meaning, and therefore, the scope of the present invention should not be construed as being limited.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (13)

1. A knee joint prosthesis, comprising:

a tibial plateau (10);

a femoral condyle component (20) located above the tibial plateau (10), the femoral condyle component (20) comprising a medial condyle articular surface (21) and a lateral condyle articular surface (22), wherein the medial condyle articular surface (21) and the lateral condyle articular surface (22) have a height difference H therebetween;

a shim component (30) located between the tibial plateau (10) and the femoral condylar component (20), the shim component (30) including a medial shim (34) cooperating with the medial condylar articular surface (21) and a lateral shim (35) cooperating with the lateral condylar articular surface (22), the upper surface of the tibial plateau (10) having a first spherical convex surface (11) in a position corresponding to the lateral shim (35), the lateral shim (35) being movably disposed on the tibial plateau (10), and the lower surface of the lateral shim (35) having a first spherical concave surface (31) cooperating with the first spherical convex surface (11).

2. Knee joint prosthesis according to claim 1, characterized in that the height difference H is between 0.5mm and 5 mm.

3. The knee joint prosthesis according to claim 1, wherein the lateral condylar articular surfaces (22) have a second spherical convex surface (221), and the shim member (30) has a second spherical concave surface (38) that mates with the second spherical convex surface (221).

4. The knee joint prosthesis of claim 1, wherein the lateral condylar articular surfaces (22) further have a first variable diameter convexly curved surface (222).

5. Knee joint prosthesis according to claim 1, characterized in that the medial condylar articular surface (21) has a second variable diameter convex curved surface (211) and the shim member (30) has a first variable diameter concave curved surface (37) cooperating with the second variable diameter convex curved surface (211).

6. Knee joint prosthesis according to claim 1, characterized in that the upper surface of the tibial plateau (10) has a first plane (12) in a position corresponding to the medial condylar articular surface (21), the lower surface of the medial spacer (34) having a second plane (32) cooperating with the first plane (12); alternatively, the upper surface of the tibial plateau (10) has a third spherical convex surface (13) in a position corresponding to the medial condylar articular surface (21), and the lower surface of the medial insert (34) has a third spherical concave surface (33) cooperating with the third spherical convex surface (13).

7. The knee joint prosthesis according to claim 1, wherein the tibial plateau (10) includes a plateau body (14) and a peripheral side wall (15) disposed at a circumferential edge of the plateau body (14) and a first inner side wall (161) and a second inner side wall (162) disposed inside the peripheral side wall (15), the outer spacer (35) is disposed in a first space surrounded by the first inner side wall (161) and the peripheral side wall (15), the inner spacer (34) is disposed in a second space surrounded by the second inner side wall (162) and the peripheral side wall (15), the first inner side wall (161) protrudes toward the outer spacer (35), and the second inner side wall (162) protrudes toward the inner spacer (34).

8. The knee joint prosthesis according to claim 1, wherein the tibial plateau (10) comprises a plateau body (14) and a peripheral side wall (15) disposed at a circumferential edge of the plateau body (14) and a first inner side wall (161) and a second inner side wall (162) disposed inside the peripheral side wall (15), the outer spacer (35) is movably disposed in a first space enclosed by the first inner side wall (161) and the peripheral side wall (15), and the inner spacer (34) is movably disposed in a second space enclosed by the second inner side wall (162) and the peripheral side wall (15).

9. The knee joint prosthesis according to claim 8, characterized in that the first space has a size greater than that of the lateral insert (35) to allow the lateral insert (35) to slide and/or rotate with respect to the tibial plateau (10), and the second space has a size greater than that of the medial insert (34) to allow the medial insert (34) to slide and/or rotate with respect to the tibial plateau (10).

10. The knee joint prosthesis according to claim 1, wherein the medial insert (34) is fixedly disposed on the tibial plateau (10), the insert member (30) further comprising a post (36) disposed on the medial insert (34).

11. The knee joint prosthesis of claim 10, wherein the femoral condyle component (20) further comprises a patellar slideway articular surface (23) connected between a medial condyle articular surface (21) and the lateral condyle articular surface (22) and a limit beam (24) connected between a posterior condyle of the medial condyle articular surface (21) and a posterior condyle of the lateral condyle articular surface (22), the post (36) being capable of limiting the limit beam (24).

12. Knee joint prosthesis according to claim 11, characterized in that a shaft (17) is provided on the tibial plateau (10), an inner hole (361) is provided in the post (36), the shaft (17) being inserted into the inner hole (361).

13. The knee joint prosthesis according to claim 7, wherein the tibial plateau (10) further comprises an intramedullary rod (18) disposed below the plateau body (14), a perpendicular to the upper surface of the tibial plateau (10) having an angle α with the intramedullary rod (18).

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