CN114452052A

CN114452052A - Total knee joint prosthesis

Info

Publication number: CN114452052A
Application number: CN202210158449.5A
Authority: CN
Inventors: 王晓红; 徐学方; 毕征; 宋大勇; 董骧; 胡森元; 曲铁兵
Original assignee: Beijing Naton Medical Technology Holdings Co Ltd
Current assignee: Beijing Naton Medical Technology Holdings Co Ltd
Priority date: 2022-02-21
Filing date: 2022-02-21
Publication date: 2022-05-10

Abstract

The invention provides a total knee joint prosthesis, which comprises a tibia liner and a femur prosthesis, wherein a medial articular surface is a curved surface with a sagittal radius RTM, a distal surface of a medial condyle is a curved surface which is superposed with the medial articular surface and has a sagittal radius RFM, and the ratio of RFM to RTM is more than or equal to 1:1.1 and more than or equal to 1: 1.8. The inner side joint surface of the total knee joint prosthesis is in a single-radius arc shape on the inner side sagittal plane, and the inner side joint surface and the inner side condyle have relatively high forming degree, so that the total knee joint prosthesis can stably rotate by taking the inner side as a center, a certain front and back displacement range can be provided for the inner side condyle, and the high buckling performance of the total knee joint prosthesis is improved. The higher conformity between the medial articular surface and the medial condyle also provides a larger contact area therebetween, thereby effectively reducing the wear of the total knee prosthesis and prolonging the service life.

Description

Total knee joint prosthesis

Technical Field

The invention relates to the field of orthopedic implants, in particular to a total knee joint prosthesis.

Background

Knee replacement adopts artificial knee prosthesis to replace diseased articular cartilage and meniscus plate and retains normal articular ligament and other tissues, thus having the advantages of small trauma, quick recovery, reduced pain, more natural range of motion and the like, and thus being widely applied to knee treatment.

In a normal human knee, during flexion from-5 ° (in the straightened position) to 120 ° (in the flexed position), the medial femoral condyle 1 undergoes an anterior-posterior translation of about 1.5mm (as shown in fig. 1), and the lateral femoral condyle 2 undergoes an anterior-posterior translation of about 18 mm. This motion allows the knee to rotate outward relative to the tibia about the medial condyle during flexion from an extension position to a 120 flexion position.

In the prior total knee joint prosthesis design, the tibia inner side liner is usually designed into a complete ball socket with a single radius or an approximate ball socket shape, so that the limit degree of the inner side liner to the inner side condyle is higher, and the phenomena of over-tightness, insufficient mobility of a patient and the like after the operation are discovered in clinical application. Alternatively, in some designs of the total knee prosthesis, in order to improve the above problems, the inner liner is designed as a multi-radius curved surface, which results in a deterioration of stability and a more serious wear phenomenon of the total knee prosthesis when the inner shaft rotates.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. To this end, embodiments of the present invention provide a total knee prosthesis.

The embodiment of the invention provides a total knee joint prosthesis, which comprises: the tibia liner comprises a medial articular surface and a lateral articular surface, the femoral prosthesis comprises a medial condyle matched with the medial articular surface and a lateral condyle matched with the lateral articular surface, the medial articular surface is a curved surface with a sagittal radius RTM, the distal surface of the medial condyle is a curved surface with a sagittal radius RFM superposed with the medial articular surface, and the ratio of 1:1.1 is more than or equal to RFM and the ratio of RTM is more than or equal to 1: 1.8.

The inner side joint surface of the tibia liner of the total knee joint prosthesis provided by the embodiment of the invention is in a single-radius arc shape on the inner side sagittal plane, and the inner side joint surface and the inner side condyle have relatively high forming degree but not 1:1 forming degree, so that the total knee joint prosthesis can be ensured to stably rotate by taking the inner side as a center, a certain anteroposterior displacement range can be provided for the inner side condyle, and the high buckling performance of the total knee joint prosthesis is improved. The higher conformity between the medial articular surface and the medial condyle also provides a larger contact area therebetween, thereby effectively reducing the wear of the total knee prosthesis and prolonging the service life.

In some embodiments, the ratio of the sagittal radius RFM of the distal surface of the medial condyle to the sagittal radius RTM of the medial articular surface satisfies: 1:1.15 is more than or equal to RFM, and RTM is more than or equal to 1: 1.5.

In some embodiments, the ratio of the sagittal radius RFM of the distal surface of the medial condyle to the sagittal radius RTM of the medial articular surface is 1:1.15, 1: 1.20, 1:1.25, 1:1.35, 1:1.45, 1: 1.50.

In some embodiments, the distal surface of the lateral condyle is configured as a curved surface having a sagittal radius RFL, and the anterior-posterior displacement length of the medial condyle is less than the anterior-posterior displacement length of the lateral condyle during flexion motion.

In some embodiments, the medial aspect of the lateral articular surface is configured as a sagittal curvature with a radius RTL, wherein RTL is 1:1.5 ≧ RFL ≧ 1: 2.6.

In some embodiments, the lateral articular surface is configured as a curved surface with a sagittal radius RTL.

In some embodiments, the cross-sectional line formed by the intersection of the lateral articular surface and the sagittal plane includes a plurality of consecutive arcs, and the sagittal radii of adjacent arcs are different.

In some embodiments, the total knee prosthesis is a posterior cruciate retaining prosthesis or a posterior cruciate substituting prosthesis.

Drawings

FIG. 1 is a schematic view of a knee joint flexion process.

Fig. 2 is a schematic structural view of a posterior stabilized knee prosthesis in an embodiment of the present invention.

Fig. 3 is a front view of a posterior stabilized knee prosthesis in an embodiment of the present invention.

Fig. 4 is a sectional view a-a of fig. 3.

Fig. 5 is a B-B sectional view of fig. 3.

Fig. 6 is a cross-sectional view a-a of the tibial insert of the embodiment of fig. 3.

Fig. 7 is a B-B cross-sectional view of another embodiment of a tibial insert.

Fig. 8 is a schematic structural view of a posterior cruciate ligament replacement prosthesis in an embodiment of the present invention.

Fig. 9 is an elevation view of a posterior cruciate ligament replacement prosthesis in an embodiment of the present invention.

Fig. 10 is a sectional view a-a of fig. 9.

Fig. 11 is a B-B sectional view of fig. 9.

Fig. 12 is a cross-sectional view a-a of the tibial insert of the embodiment of fig. 9.

Fig. 13 is a B-B cross-sectional view of the tibial insert of the alternative embodiment of fig. 9.

FIG. 14 is a graph of the motion of a total knee prosthesis with multi-radius medial articular surfaces of different conformity in deep squatting movements.

Figure 15 is a graph of the motion profile of a total knee prosthesis having a single radius medial articular surface with different degrees of conformity during deep squat exercises.

Fig. 16 is a graph of the motion of a total knee prosthesis having multi-radius medial articular surfaces of different degrees of conformity in a downstairs motion.

Figure 17 is a graph of the motion of a total knee prosthesis having a single radius medial articular surface with different degrees of conformity during a downstairs motion.

Fig. 18 is a graph of the motion of a total knee prosthesis having multi-radius medial articular surfaces of different degrees of conformity during upstairs motion.

Figure 19 is a graph of the motion of a total knee prosthesis having a single radius medial articular surface with different degrees of conformity during upstairs motion.

FIG. 20 is a graphical representation of the amount of wear of a total knee prosthesis having single radius or multi-radius medial articular surfaces during different movements.

Reference numerals:

100. a tibial insert; 110. an inner liner; 111. a medial articular surface; 120. an outer liner; 121. a lateral articular surface;

200. a femoral prosthesis; 210. a medial condyle; 220. the lateral condyle; 300. a tibial tray.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In order to better explain and explain the technical solution of the present invention, the directions and the like involved in the present invention are explained and explained in conjunction with the general description method in the art.

In the field of anatomy and medical instruments, directions and planes of medial, lateral, anterior, posterior, distal, proximal, sagittal, coronal, transverse, and the like have specific meanings and are well known to those skilled in the art, and unless otherwise indicated, these terms are intended to have meanings recognized by those skilled in the art, and the following is a brief description of the terms referred to in this application in order to better understand the technical solutions.

When describing a human body, a joint or a prosthesis, the sagittal plane refers to a longitudinal section which divides the human body or the joint into a left part and a right part from the front to the back, wherein the sagittal plane passing through the middle of the human body is the middle sagittal plane which divides the human body into two equal parts. It is understood that the sagittal plane refers to a plane of a person when standing normally upright, with the knee joint bending angle being 0 °. When the knee joint or the knee joint prosthesis is stretched and bent or the posture of the human body is adjusted, the tangent plane can be changed accordingly.

Generally, when describing a human body, a joint or a prosthesis, three different types of directions are involved: far and near, inside and outside, and front and back. Wherein, the far end refers to the end of the human body or the joint which is relatively far away from the head. Proximal refers to the end of the body or joint that is relatively close to the head. The medial side refers to the side that is relatively close to the midsagittal plane of the human body. Lateral refers to the side of the body that is relatively far from the midsagittal plane of the body. The anterior side refers to the side on the sagittal plane that is relatively near the chest. The posterior side refers to the side on the sagittal plane that is relatively close to the back.

In particular, embodiments of the present application provide a total knee prosthesis for replacing a knee joint in a knee replacement procedure. It will be appreciated that a total knee prosthesis includes a left knee prosthesis and a right knee prosthesis, each adapted for use with a left leg, wherein the left knee prosthesis and the right knee prosthesis are radially symmetric about a midsagittal plane of the human body.

The structure of a total knee prosthesis provided by an embodiment of the present invention will be described below with reference to fig. 2 to 20.

The total knee prosthesis includes a tibial insert 100, a femoral prosthesis 200, and a tibial tray 300. The tibial insert 100 and the femoral prosthesis 200 cooperate to form a joint that allows flexion motion. The tibial tray 300 is attached to the side of the tibial insert 100 remote from the femoral prosthesis 200.

The tibial insert 100 is used to replace the tibial lateral meniscus in knee replacement surgery and includes a medial insert 110 and a lateral insert 120. The medial pad 110 is positioned medial to the lateral pad 120, i.e., the medial pad 110 is positioned approximately mid-sagittal of the human body relative to the lateral pad 120. The proximal surface of the medial pad 110 is the medial articular surface 111 and the proximal surface of the lateral pad 120 is the lateral articular surface 121. The femoral prosthesis 200 includes a medial condyle 210 and a lateral condyle 220.

The medial articular surface 111 cooperates with the medial condyle 210 and the lateral articular surface cooperates with the lateral condyle 220. When the knee joint prosthesis is in motion, the femoral prosthesis 200 rotates around the medial condyle 210 as an axis, the medial condyle 210 performs translational and rotational motion along the motion track on the medial articular surface 111, and the lateral condyle 220 performs translational and rotational motion along the motion track on the lateral articular surface.

The medial articular surface 111 is configured as a RTM sagittal curvature surface and the distal surface of the medial condyle 210 is configured as an RFM sagittal curvature surface superimposed with the medial articular surface 111. The sagittal radius may also be referred to as the radius of curvature. Specifically, the cross-sectional line formed by the intersection of the medial articular surface 111 and the sagittal plane is an arc having a single sagittal radius RTM. In the embodiment of the application, the ratio of RFM to RTM is 1:1.1 ≧ RFM: 1:1.8, and RFM: RTM can be used for representing the degree of conformity between the medial articular surface 111 and the medial condyle 210 and can also be referred to as the medial degree of conformity, and the smaller RFM: RTM indicates the lower the medial degree of conformity of the total knee prosthesis, and the larger RFM: RTM indicates the higher the medial degree of conformity of the total knee prosthesis.

When RFM: RTM is greater than 1:1.1, the too high conformity between the medial articular surface 111 and the medial condyle 210 leads to the great restriction on the displacement of the medial condyle 210 in the anterior-posterior direction when the total knee prosthesis rotates around the medial condyle 210, and the phenomena of over-tight joint, insufficient mobility of the patient and the like easily occur after the operation; when RFM: RTM is less than 1:1.8, the degree of conformity between the medial articular surface 111 and the medial condyle 210 is low, which may cause unstable fitting between the medial condyle 210 and the medial articular surface 111 when the total knee prosthesis rotates around the medial condyle 210, and may cause dislocation of the total knee prosthesis in serious cases, and may also cause a reduction in the contact area between the medial articular surface 111 and the medial condyle 210, thereby increasing wear of the total knee prosthesis and reducing the service life of the total knee prosthesis.

The total knee prosthesis provided by the embodiments of the present invention may be a posterior stabilized knee prosthesis as shown in fig. 2-7 or a posterior cruciate ligament replacement prosthesis as shown in fig. 8-13. The posterior stabilized knee prosthesis has a post-cam structure. After flexion to an angle, the Post structures on the tibial insert 100 contact the cam structures on the femoral prosthesis 200, which may allow further posterior rolling of the femoral condyle. The posterior stabilized knee prosthesis does not have a post-cam configuration and rollback of the femoral prosthesis 200 is achieved by cooperation of the articular surfaces between the femoral prosthesis 200 and the tibial insert 100.

Fig. 6 is a cross-sectional view a-a of tibial insert 100 of a posterior stabilized knee prosthesis. Section A-A is the medial sagittal plane, corresponding to the extent of the contact path during cooperation of the medial articular surface 111 with the medial condyle 210. Fig. 12 is an a-a cross-sectional view of a tibial insert 100 of a posterior cruciate ligament replacement prosthesis. Section A-A is the medial sagittal plane. The intersection of the medial articular surface 111 and the medial sagittal plane in figures 6 and 12 forms a cross-sectional line that is an arc of a circle having a single sagittal radius RTM.

Under the condition of high load bending degree, the medial anteroposterior displacement of the total knee joint prosthesis is smaller than the lateral anteroposterior displacement. That is, the amount of displacement of the medial condyle 210 in the anterior-posterior direction is less than the amount of displacement of the lateral condyle 220 in the anterior-posterior direction. For example, as shown in the motion curves of the medial and lateral anteroposterior displacement amounts in the deep squat exercise of fig. 14 and 15, when the human body performs the deep squat exercise, the flexion angle of the knee gradually increases with the increase of the exercise cycle, and when the deep squat exercise cycle reaches 100%, the flexion degree is 150 °. Both fig. 14 and 15 show that the medial anteroposterior displacement is less than the lateral anteroposterior displacement regardless of whether the medial articular surface 111 is of a single radius configuration or of a multi-radius configuration.

When the medial articular surface 111 has a multi-radius configuration, the kinematics is not significantly affected by conformity. For example, as shown in fig. 14, 16, and 18, the degree of formation is in the range of 1: 1.0-1: 1.8, the ipsilateral motion profiles of the total knee prosthesis were relatively close and did not show much difference. It should be noted that the "degree of formation X" in fig. 14-20 indicates a degree of formation of 1: X, for example, the "degree of formation 1.2" specifically indicates a degree of formation of 1: 1.2.

Furthermore, compared with the total knee joint prosthesis with a multi-radius design in the related art, the total knee joint prosthesis with a single-radius design has smaller displacement amount on the inner side, and the inner shaft has more reliable stability during rotation, thereby being more in line with the motion structure of the human body. This is due to the relatively high conformity between the medial articular surface 111 and the medial condyle 210, which ensures stable medial-centered rotation of the total knee prosthesis.

For example, as shown in fig. 15, during deep squat, the displacement curve indicated by "multi-radius-conformity 1.0-medial" is located above the displacement curves indicated by "single-radius-conformity 1.15-1.8-medial", indicating that the total knee prosthesis with a single-radius design has a smaller medial displacement. It should be noted that, as mentioned above, when the medial articular surface 111 has a multi-radius structure, the conformity has little influence on the kinematics, so it is reasonable to choose a multi-radius design with conformity of 1.0 in fig. 15 to compare with a single radius design, and the experimental conclusion is not affected.

When the inner side forming degree of the total knee joint prosthesis with the single-radius design changes within a certain range, the corresponding performance of the total knee joint prosthesis can be kept, and compared with the total knee joint prosthesis with the multi-radius design in the related technology, the total knee joint prosthesis provided by the embodiment of the application has more stable performance under low flexion in the motions of going upstairs and downstairs and the like.

Typically, when a person is moving upstairs, the low flexion period has a motion cycle in the range of 0% -10%, and 60% -100%, and the others are high flexion periods. The motion cycle of the low-flexion period of the downstairs motion is 0% -50%, the range of 90% -100%, and the other periods are the high-flexion period.

Low flexion period during downstairs movement: when the ratio of 1:1.15 is more than or equal to RFM and the ratio of RTM is more than or equal to 1:1.5, the inner side displacement of the single-radius designed total knee prosthesis is far less than that of the multi-radius designed total knee prosthesis, and the stability is more obvious; when the conformity is less than 1:1.50, the medial displacement of the single-radius designed total knee prosthesis is closer to that of the multi-radius designed total knee prosthesis, i.e. the medial displacement is larger. This is due to the low degree of conformity during low flexion periods during downstairs motion, which may result in an unstable fit between the medial condyle 210 and the medial articular surface 111 as the total knee prosthesis rotates about the medial condyle 210. Thus, preferably, the ratio of the sagittal radius RFM of the distal surface of the medial condyle 210 to the sagittal radius RTM of the medial articular surface 111 satisfies: 1:1.15 is more than or equal to RFM, and RTM is more than or equal to 1: 1.5.

For example, as shown in the motion graph of a total knee prosthesis with a single radius medial articular surface having different degrees of conformity during downstairs motion of fig. 17, the degree of conformity is between 1: 1.15-1: under the condition of 1.5, the inner side displacement of the single-radius designed total knee joint prosthesis is obviously lower than that of the multi-radius designed total knee joint prosthesis, the stability is more obvious, and in the process that the forming degree is gradually increased from 1:1.5 to 1:1.8, the inner side displacement of the single-radius designed total knee joint prosthesis gradually approaches to that of the multi-radius designed total knee joint prosthesis.

It is noted that the sagittal plane of the medial pad of a multiradius total knee prosthesis is comprised of segments having multiple radii, the conformity being the ratio of the medial condyle sagittal radius to the sagittal radius at the distal (medial) portion of the medial articular surface.

Further optionally, the ratio RFM: RTM of the sagittal radius RFM of the distal surface of the medial condyle 210 to the sagittal radius RTM of the medial articular surface 111 is 1:1.15, 1; 1.20, 1:1.25, 1:1.35, 1:1.45, 1: 1.50.

Furthermore, the low flexion period during the upstairs movement: when the ratio of 1:1.15 is more than or equal to RFM and the ratio of RTM is more than or equal to 1:1.5, the inner side displacement of the single-radius designed total knee prosthesis is far less than that of the multi-radius designed total knee prosthesis, and the stability is more obvious; when the forming degree is less than 1:1.50, the medial displacement of the single-radius designed total knee prosthesis is closer to that of the multi-radius designed total knee prosthesis, namely the medial displacement is larger. This is due to the fact that during periods of low flexion during downstairs motion, a low degree of conformity may result in an unstable fit between the medial condyle 210 and the medial articular surface 111 as the total knee prosthesis rotates about the medial condyle 210.

For example, as shown in the motion profile of a total knee prosthesis having a single radius medial articular surface with different degrees of conformity during upstairs motion of fig. 19, the degree of conformity is between 1: 1.15-1: under the condition of 1.5, the inner side displacement of the single-radius designed total knee joint prosthesis is obviously lower than that of the multi-radius designed total knee joint prosthesis, the stability is more obvious, and in the process that the forming degree is gradually increased from 1:1.5 to 1:1.8, the inner side displacement of the single-radius designed total knee joint prosthesis gradually approaches to that of the multi-radius designed total knee joint prosthesis.

In addition, the embodiments of the present application provide a total knee prosthesis having a single radius design that has a significantly reduced amount of wear as compared to prior art total knee prostheses having a multi-radius design. This is because the higher conformity between the medial articular surface and the medial condyle increases the contact area between them, which effectively reduces wear of the total knee prosthesis and prolongs its service life. For example, as shown in fig. 20, the total knee prosthesis in the embodiment of the present application has a medial conformity of 1: 1.15-1: 1.8, the total amount of wear of the total knee prosthesis is less than the total amount of wear of a total knee prosthesis having a multi-radius design. And the abrasion loss of the total knee joint prosthesis tends to be increased along with the gradual decrease of the forming degree towards 1: 1.8.

The stress of the inner and outer condyles of the knee joint surface of the human body is asymmetrical in daily movement. For example, when the person stands up from the chair, the medial articular surface of the tibial insert is loaded four times as much as the lateral articular surface, and, for example, when the person is squatting, the medial articular surface is loaded eight times as much as the lateral articular surface. This also requires the medial and lateral articular surfaces of the tibial insert of the knee joint to be of asymmetric design. Therefore, in the design of a total knee joint, it is necessary that the knee joint rotates about the medial side and that the medial articular surface has a certain range of anterior-posterior displacement, and that the lateral condyle of the knee joint be less restricted and that the lateral spacer have a suitable contour.

In the inventive concept of the present application, there is a high degree of conformity between the medial condyle 210 and the medial articular surface 111 of the tibial insert. In the sagittal plane, the medial articular surface 111 is a single radius with a smaller radius, and the medial articular surface 111 is raised anteriorly and posteriorly relative to the lateral articular surface 121 at the sagittal plane nadir faster and more, thereby limiting anterior-posterior translation of the medial condyle 210 and facilitating medial-centered rotation of the total knee prosthesis. While there is a lower conformity between the lateral condyle 220 and the lateral articular surface 121 of the tibial insert.

FIG. 5 is a cross-sectional view B-B of a posterior stabilized knee prosthesis. Section B-B is the lateral sagittal plane corresponding to the extent of the path of contact during mating of the lateral articular surface 121 with the lateral condyle 220. Fig. 11 is a B-B cross-sectional view of a posterior cruciate ligament replacement prosthesis. Section B-B is the lateral sagittal plane. The distal surface of lateral condyle 220 in FIGS. 5 and 11 is configured as a curved surface having a sagittal radius RFL.

The middle part of the lateral articular surface 121 is constructed as a curved surface with a sagittal radius RTL, wherein 1:1.5 is more than or equal to RFL, and RTL is more than or equal to 1: 2.6. The medial portion of the lateral articular surface 121 refers to the portion that mates with the distal end of the lateral condyle 220. The lower conformity between the lateral condyle 220 and the lateral articular surface 121 of the tibial insert facilitates greater anterior-posterior displacement of the lateral condyle 220 during flexion, thereby allowing the femoral prosthesis 200 to rotate outwardly more relative to the tibial insert 100 and more closely conform to the biomimetic structure.

Alternatively, as shown in FIG. 5, the lateral articular surface 121 is configured as a curved surface with a sagittal radius RTL, i.e., the cross-sectional lines that the lateral articular surface 121 intersects with the lateral sagittal plane are all arcs of a circle having a single sagittal radius RTL. Wherein, 1:1.5 is more than or equal to RFL, and RTL is more than or equal to 1: 2.6.

Alternatively, as shown in FIG. 7, the lateral articular surface 121 has multiple sagittal radii. Specifically, the cross-sectional line formed by the intersection of the lateral articular surface 121 and the lateral sagittal plane includes a plurality of consecutive arcs, and the sagittal radii of two adjacent arcs are different. When the knee joint is flexed, the different sagittal radii of the lateral articular surface 121 can adjust the posterior movement speed of the lateral condyle 220, so as to adjust the external rotation angle of the lateral condyle 220 at different flexion angles, thereby better conforming to the natural state of the knee joint of the human body.

In the embodiment shown in FIG. 7, the lateral articular surface 121 arc includes three segments, with the arc in the middle having a sagittal radius greater than each of the remaining two arcs. Specifically, as shown in FIG. 7, the first arc of the anterior-medial portion has a first sagittal radius RTL1, the second arc of the medial-posterior portion has a second sagittal radius RTL2, and the third arc of the posterior portion has a lateral third sagittal radius RTL 3. The size of the second sagittal radius RTL2 of the second segment of the arc will affect the angle of rotation of the lateral condyle 220 in moderate flexion. RTL2 may tend to be larger for different rotation angles of lateral condyle 220, where the second arc is closer to a straight line. In other embodiments, RTL2 may also be the same as RTL1 and RTL 3. In the present embodiment, 1: 1.5. gtoreq.RFL and RTL 1. gtoreq.1: 2.6.

Alternatively, as shown in FIG. 11, the lateral articular surface is configured as a curved surface with a sagittal radius RTL, i.e., the cross-sectional lines that the lateral articular surface 121 intersects with the lateral sagittal plane are all arcs of a circle having a single sagittal radius RTL. Wherein, 1:1.5 is more than or equal to RFL, and RTL is more than or equal to 1: 2.6. The lower conformity between the lateral condyle 220 and the lateral articular surface 121 of the tibial insert facilitates greater anterior-posterior displacement of the lateral condyle 220 during flexion, thereby allowing the femoral prosthesis 200 to rotate outwardly more relative to the tibial insert 100 and more closely conform to the biomimetic structure.

Alternatively, as shown in FIG. 13, the lateral articular surface 121 has multiple sagittal radii. Specifically, the cross-sectional line formed by the intersection of the lateral articular surface 121 and the sagittal plane includes a plurality of sequentially connected arcs, and the sagittal radii of two adjacent arcs are different. When the knee joint is flexed, the different sagittal radii of the lateral articular surface 121 can adjust the posterior movement speed of the lateral condyle 220, so as to adjust the external rotation angle of the lateral condyle 220 at different flexion angles, thereby better conforming to the natural state of the knee joint of the human body.

In the embodiment shown in FIG. 13, the lateral articular surface 121 arc includes three segments, with the arc in the middle having a sagittal radius greater than each of the remaining two arcs. Specifically, as shown in FIG. 13, the first arc of the anterior-medial portion has a first sagittal radius RTL1, the second arc of the medial-posterior portion has a second sagittal radius RTL2, and the third arc of the posterior portion has a third lateral sagittal radius RTL 3. The second sagittal radius RTL2 for the second arc segment is sized to affect the angle of rotation of the lateral condyle 220 in moderate flexion. RTL2 may tend to be larger for different rotation angles of lateral condyle 220, where the second arc is closer to a straight line. In other embodiments, RTL2 may also be the same as RTL1 and RTL 3. In the present embodiment, 1: 1.5. gtoreq.RFL and RTL 1. gtoreq.1: 2.6. Alternatively, in other embodiments, the RTL2 may be smaller than the RTL1 or smaller than the RTL3, which is not limited in this embodiment.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.

In the present invention, unless otherwise explicitly stated or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly, e.g., as being permanently connected, detachably connected, or integral; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be interconnected within two elements or in a relationship where two elements interact with each other unless otherwise specifically limited. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the second feature or the first and second features may be indirectly contacting each other through intervening media. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the present disclosure, the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" and the like mean that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A total knee prosthesis, comprising:

the tibia liner comprises a medial articular surface and a lateral articular surface, the femoral prosthesis comprises a medial condyle matched with the medial articular surface and a lateral condyle matched with the lateral articular surface, the medial articular surface is a curved surface with a sagittal radius RTM, the distal surface of the medial condyle is a curved surface with a sagittal radius RFM superposed with the medial articular surface, and the ratio of 1:1.1 is more than or equal to RFM and the ratio of RTM is more than or equal to 1: 1.8.

2. The total knee prosthesis of claim 1, wherein a ratio of a sagittal radius RFM of the distal surface of the medial condyle to a sagittal radius RTM of the medial articular surface satisfies: 1:1.15 is more than or equal to RFM, RTM is more than or equal to 1: 1.5.

3. The total knee prosthesis of claim 2, wherein the ratio of the sagittal radius RFM of the distal surface of the medial condyle to the sagittal radius RTM of the medial articular surface is 1:1.15, 1: 1.20, 1:1.25, 1:1.35, 1:1.45, 1: 1.50.

4. The total knee prosthesis of claim 1, wherein the distal surface of the lateral condyle is configured as a curved surface having a sagittal radius RFL, and the anterior-posterior displacement length of the medial condyle is less than the anterior-posterior displacement length of the lateral condyle during the flexion motion.

5. The total knee prosthesis of claim 4, wherein the medial aspect of the lateral articular surface is configured as a curved surface with a sagittal radius RTL, wherein 1:1.5 ≧ RFL ≧ 1: 2.6.

6. The total knee prosthesis of claim 4, wherein the lateral articular surface is configured as a curved surface with a sagittal radius RTL.

7. The total knee prosthesis of claim 4, wherein the cross-sectional line formed by the intersection of the lateral articular surface and the sagittal plane includes successive segments of circular arcs, adjacent segments of the circular arcs having different sagittal radii.

8. The total knee prosthesis of any one of claims 1-7, wherein the total knee prosthesis is a posterior cruciate ligament retaining prosthesis or a posterior cruciate ligament replacement prosthesis.