Total knee prosthesis

Abstract

This invention proposes a total knee arthroplasty, comprising a tibial liner and a femoral prosthesis. The medial articular surface is constructed as a curved surface with a sagittal radius of RTM, and the distal surface of the medial condyle is constructed as a curved surface with a sagittal radius of RFM that overlaps with the medial articular surface, wherein 1:1.1≥RFM:RTM≥1:1.8. The medial articular surface of the proposed total knee arthroplasty is an arc with a single radius in the medial sagittal plane, and there is a relatively high fit between the medial articular surface and the medial condyle. This ensures stable rotation of the total knee arthroplasty around the medial side and provides a certain range of anterior-posterior displacement for the medial condyle, improving the high flexion performance of the total knee arthroplasty. The high fit between the medial articular surface and the medial condyle also provides a large contact area, effectively reducing wear on the total knee arthroplasty and extending its service life.

Description

Technical Field

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

[0002] Knee replacement surgery uses an artificial knee joint prosthesis to replace the diseased articular cartilage and meniscus while preserving the normal joint ligaments and other tissues. As a result, it has the advantages of minimal trauma, rapid recovery, reduced pain, and a more natural range of motion. Therefore, knee replacement surgery is widely used in the treatment of knee joint problems.

[0003] In a normal person, during knee flexion from -5° (extended position) to 120° (bent position), the medial femoral condyle 1 undergoes approximately 1.5 mm of anterior-posterior translation (e.g., ...). Figure 1 As shown in the diagram, the lateral femoral condyle 2 undergoes approximately 18 mm of anterior-posterior translation. This movement causes the femur to externally rotate relative to the tibia around the medial condyle during knee flexion from extension to 120° flexion.

[0004] In previous total knee arthroplasty designs, the medial tibial pad was typically designed as a single-radius ball-and-socket or near-ball-and-socket shape. This resulted in a high degree of restriction on the medial condyle by the medial pad, leading to postoperative issues such as excessive tightness and insufficient patient mobility. Alternatively, some total knee arthroplasty designs attempted to address these problems by using a multi-radius curved surface for the medial pad. However, this resulted in decreased stability during rotation around the internal axis of the total knee arthroplasty and more severe wear. Summary of the Invention

[0005] This invention aims to at least partially address one of the technical problems in related technologies. To this end, embodiments of this invention propose a total knee joint prosthesis.

[0006] The total knee joint prosthesis proposed in this invention includes a tibial liner and a femoral prosthesis. The tibial liner includes a medial articular surface and a lateral articular surface. The femoral prosthesis includes a medial condyle that mates with the medial articular surface and a lateral condyle that mates with the lateral articular surface. The medial articular surface is constructed as a curved surface with a sagittal radius of RTM, and the distal surface of the medial condyle is constructed as a curved surface with a sagittal radius of RFM that overlaps with the medial articular surface, wherein 1:1.1≥RFM:RTM≥1:1.8.

[0007] The medial articular surface of the tibial liner of the total knee arthroplasty provided in this embodiment of the invention is an arc with a single radius in the medial sagittal plane, and the medial articular surface has a relatively high, but not 1:1, fit with the medial condyle. This ensures stable rotation of the total knee arthroplasty around the medial side, while also providing a certain range of anterior-posterior displacement for the medial condyle, thus improving the high flexion performance of the total knee arthroplasty. The high fit between the medial articular surface and the medial condyle also provides a larger contact area between them, thereby effectively reducing wear on the total knee arthroplasty and extending its service life.

[0008] 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≥RFM:RTM≥1:1.5.

[0009] 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 one of 1:1.15, 1:1.20, 1:1.25, 1:1.35, 1:1.45, and 1:1.50.

[0010] In some embodiments, the distal surface of the lateral condyle is constructed as a curved surface with a sagittal radius RFL, and during flexion, the anterior-posterior displacement length of the medial condyle is less than that of the lateral condyle.

[0011] In some embodiments, the middle portion of the lateral articular surface is constructed as a curved surface with a sagittal radius of RTL, wherein 1:1.5≥RFL:RTL≥1:2.6.

[0012] In some embodiments, the lateral articular surface is constructed as a curved surface with a sagittal radius of RTL.

[0013] In some embodiments, the cross-sectional line formed by the intersection of the lateral articular surface and the sagittal plane includes multiple arc segments connected in sequence, with adjacent arc segments having different sagittal radii.

[0014] In some embodiments, the total knee joint prosthesis is a posterior cruciate ligament-preserving prosthesis or a posterior cruciate ligament replacement prosthesis. Attached Figure Description

[0015] Figure 1 This is a diagram illustrating the knee flexion process.

[0016] Figure 2 This is a schematic diagram of the structure of the posteriorly stabilized knee joint prosthesis in an embodiment of the present invention.

[0017] Figure 3 This is a front view of the posteriorly stabilized knee joint prosthesis in an embodiment of the present invention.

[0018] Figure 4 yes Figure 3 AA section diagram.

[0019] Figure 5 yes Figure 3 BB cross-sectional view.

[0020] Figure 6 yes Figure 3 A cross-sectional view of the tibial liner in the embodiment.

[0021] Figure 7 This is a BB cross-sectional view of the tibial liner in another embodiment.

[0022] Figure 8 This is a schematic diagram of the posterior cruciate ligament replacement prosthesis in an embodiment of the present invention.

[0023] Figure 9 This is a front view of the posterior cruciate ligament replacement prosthesis in an embodiment of the present invention.

[0024] Figure 10 yes Figure 9 AA section diagram.

[0025] Figure 11 yes Figure 9 BB cross-sectional view.

[0026] Figure 12 yes Figure 9 A cross-sectional view of the tibial liner in the embodiment.

[0027] Figure 13 yes Figure 9 A BB cross-sectional view of the tibial liner in another embodiment.

[0028] Figure 14 It is a motion curve diagram of a total knee joint prosthesis with multiple radii of medial articular surfaces and different fit during squatting exercises.

[0029] Figure 15 It is a motion curve diagram of a total knee joint prosthesis with a single radius medial articular surface having different fit during a squat exercise.

[0030] Figure 16 It is a motion curve diagram of a total knee prosthesis with multiple radii of medial articular surfaces and different degrees of fit during the movement of going downstairs.

[0031] Figure 17 It is a motion curve diagram of a total knee joint prosthesis with a single radius medial articular surface having different degrees of fit during a downstairs movement.

[0032] Figure 18 It is a motion curve diagram of a total knee joint prosthesis with multiple radii of medial articular surfaces and different degrees of fit during the movement of climbing stairs.

[0033] Figure 19 It is a motion curve diagram of a total knee joint prosthesis with a single radius medial articular surface having different degrees of fit during the movement of climbing stairs.

[0034] Figure 20 This is a schematic diagram showing the wear of a total knee joint prosthesis with a single or multiple radius medial articular surfaces during different movements.

[0035] Figure label:

[0036] 100. Tibial pad; 110. Medial pad; 111. Medial articular surface; 120. Lateral pad; 121. Lateral articular surface;

[0037] 200. Femoral prosthesis; 210. Medial condyle; 220. Lateral condyle; 300. Tibial support. Detailed Implementation

[0038] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0039] To better explain and illustrate the technical solutions of the present invention, the directions and other aspects involved in the present invention will be explained and described in conjunction with the conventional descriptive methods in the art.

[0040] In the fields of anatomy and medical devices, directions and planes such as internal, external, anterior, posterior, distal, proximal, sagittal, coronal, and cross-section have specific meanings and are well known to those skilled in the art. Unless otherwise specified, these terms refer to the meanings generally accepted by those skilled in the art. The following is a brief explanation of the terms involved in this application to better understand the technical solution.

[0041] When describing the human body, joints, or prostheses, the sagittal plane refers to a longitudinal section that divides the body or joint into left and right parts from the front-to-back direction. The sagittal plane passing through the center of the body is called the median sagittal plane, which divides the body into two equal parts. It can be understood that the sagittal plane described above refers to the section when a person is standing normally upright, at which point the knee flexion angle is 0°. When the knee joint or knee prosthesis flexes or extends, or when the body's posture is adjusted, the section can change accordingly.

[0042] Typically, when describing the human body, joints, or prostheses, three different directions are involved: distal, medial, and posterior. The distal end refers to the end of the body or joint relatively far from the head. The proximal end refers to the end of the body or joint relatively close to the head. The medial side refers to the side relatively close to the midsagittal plane of the body. The lateral side refers to the side relatively far from the midsagittal plane of the body. The anterior side refers to the side relatively close to the chest in the sagittal plane. The posterior side refers to the side relatively close to the back in the sagittal plane.

[0043] Specifically, this application provides a total knee arthroplasty for use in knee replacement surgery. It is understood that the total knee arthroplasty includes a left knee prosthesis for the left leg and a right knee prosthesis, wherein the left and right knee prostheses are radially symmetrical about the midsagittal plane of the human body.

[0044] The following is based on Figures 2-20 The structure of the total knee joint prosthesis provided in the embodiments of the present invention is described.

[0045] The total knee joint prosthesis includes a tibial pad 100, a femoral prosthesis 200, and a tibial support 300. The tibial pad 100 and the femoral prosthesis 200 work together to form a joint capable of flexion. The tibial support 300 is connected to the side of the tibial pad 100 away from the femoral prosthesis 200.

[0046] The tibial liner 100, used in knee replacement surgery to replace the lateral meniscus of the tibia, includes a medial liner 110 and a lateral liner 120. The medial liner 110 is located medial to the lateral liner 120, meaning the medial liner 110 is closer to the midsagittal plane of the body than the lateral liner 120. The proximal surface of the medial liner 110 is the medial articular surface 111, and the proximal surface of the lateral liner 120 is the lateral articular surface 121. The femoral prosthesis 200 includes a medial condyle 210 and a lateral condyle 220.

[0047] The medial articular surface 111 engages with the medial condyle 210, and the lateral articular surface engages with the lateral condyle 220. During knee joint movement, the femoral prosthesis 200 rotates around the medial condyle 210 as an axis. The medial condyle 210 performs translational and rotational movements along the movement trajectory on the medial articular surface 111, and the lateral condyle 220 performs translational and rotational movements along the movement trajectory on the lateral articular surface.

[0048] The medial articular surface 111 is constructed as a curved surface with a sagittal radius of RTM, and the distal surface of the medial condyle 210 is constructed as a curved surface with a sagittal radius of RFM that overlaps with the medial articular surface 111. The sagittal radius can also be called the radius of curvature. Specifically, the cross-sectional line formed by the intersection of the medial articular surface 111 and the sagittal surface is an arc with a single sagittal radius of RTM. In the embodiments of this application, 1:1.1≥RFM:RTM≥1:1.8. RFM:RTM can be used to characterize the fit between the medial articular surface 111 and the medial condyle 210, which can also be called the medial fit. The smaller the RFM:RTM, the lower the medial fit of the total knee joint prosthesis; the larger the RFM:RTM, the higher the medial fit of the total knee joint prosthesis.

[0049] When the RFM:RTM ratio is greater than 1:1.1, the fit between the medial articular surface 111 and the medial condyle 210 is too high. This will result in significant restriction of the anteroposterior displacement of the medial condyle 210 when the total knee arthroplasty rotates around the medial condyle 210, which may lead to joint tightness and insufficient patient mobility postoperatively. When the RFM:RTM ratio is less than 1:1.8, the fit between the medial articular surface 111 and the medial condyle 210 is too low. This will result in unstable fit between the medial condyle 210 and the medial articular surface 111 when the total knee arthroplasty rotates around the medial condyle 210, which may lead to knee prosthesis dislocation in severe cases. In addition, it will also reduce the contact area between the medial articular surface 111 and the medial condyle 210, aggravating the wear of the total knee arthroplasty and reducing its service life.

[0050] The medial articular surface of the tibial liner of the total knee arthroplasty provided in this embodiment of the invention is an arc with a single radius in the medial sagittal plane, and the medial articular surface has a relatively high, but not 1:1, fit with the medial condyle. This ensures stable rotation of the total knee arthroplasty around the medial side, while also providing a certain range of anterior-posterior displacement for the medial condyle, thus improving the high flexion performance of the total knee arthroplasty. The high fit between the medial articular surface and the medial condyle also provides a larger contact area between them, thereby effectively reducing wear on the total knee arthroplasty and extending its service life.

[0051] The total knee joint prosthesis provided in this embodiment of the invention can be Figures 2-7 The posterior stabilized knee prosthesis shown or such Figures 8-13 The diagram shows a posterior cruciate ligament (PCL) replacement prosthesis. Posteriorly stabilized knee prostheses have a post-cam structure. Upon flexion to a certain angle, the post structure on the tibial pad 100 contacts the cam structure on the femoral prosthesis 200, allowing for further posterior rolling of the femoral condyle. Posteriorly stabilized knee prostheses do not have a post-cam structure; posterior rolling of the femoral prosthesis 200 is achieved through the interaction of the articular surfaces between the femoral prosthesis 200 and the tibial pad 100.

[0052] Figure 6 This is a cross-sectional view (AA) of the tibial liner 100 of the posteriorly stable knee joint prosthesis. Section AA is the medial sagittal plane, corresponding to the range of the contact path during the mating process between the medial articular surface 111 and the medial condyle 210. Figure 12 This is a cross-sectional view (AA) of the tibial liner 100 of the posterior cruciate ligament replacement prosthesis. Cross-section AA is the medial sagittal plane. Figure 6 and Figure 12 The cross-sectional lines formed by the intersection of the medial articular surface 111 and the medial sagittal surface are all circular arcs with a single sagittal radius RTM.

[0053] Under heavy load and high flexion, the medial anteroposterior displacement of a total knee prosthesis is less than the lateral anteroposterior displacement. In other words, the anteroposterior displacement of the medial condyle 210 is less than that of the lateral condyle 220. For example... Figure 14 and Figure 15 The motion curves showing the displacement of the inner and outer sides during squatting indicate that the knee flexion angle gradually increases with the increase of the exercise cycle during squatting. When the squatting exercise cycle reaches 100%, the flexion angle is 150°. Figure 14 and Figure 15 All of these results show that, regardless of whether the medial articular surface 111 is a single-radius structure or a multi-radius structure, the medial anterior-posterior displacement is less than the lateral anterior-posterior displacement.

[0054] When the medial articular surface 111 is a multi-radius structure, the fit has little effect on the kinematics. For example... Figure 14 , Figure 16 and Figure 18 As shown, during the fit variation from 1:1.0 to 1:1.8, the ipsilateral motion curves of the total knee prosthesis were quite similar, showing no significant differences. It should be noted that... Figures 14-20 The "form fit X" mentioned in the text refers to a form fit of 1:X. For example, "form fit 1.2" in the figure specifically means a form fit of 1:1.2.

[0055] Furthermore, compared to total knee prostheses with multi-radius designs in related technologies, total knee prostheses with a single-radius design exhibit smaller medial displacement, more reliable stability during internal axis rotation, and better conformity to human movement structures. This is because the medial articular surface 111 and the medial condyle 210 have a relatively high fit, ensuring stable rotation of the total knee prosthesis around the medial side.

[0056] For example Figure 15 As shown, during the squatting motion, the displacement curve indicated by "multi-radius - fit 1.0 - medial" is above several displacement curves indicated by "single-radius - fit 1.15-1.8 - medial," indicating that the medial displacement of the total knee prosthesis with a single-radius design is smaller. It should be noted that, as mentioned above, when the medial articular surface 111 has a multi-radius structure, the fit has little impact on kinematics; therefore... Figure 15 It is reasonable to compare the multi-radius design with a form fit of 1.0 with the single-radius design, and this will not affect the experimental conclusions.

[0057] The total knee prosthesis with a single radius design provided in this application maintains its corresponding performance even when the medial conformation varies within a certain range. Compared with total knee prostheses with multi-radius designs in related technologies, the total knee prosthesis provided in this application has more stable performance under low flexion during activities such as going up and down stairs.

[0058] Typically, when a person is climbing stairs, the low flexion period ranges from 0% to 10% and from 60% to 100%, with the rest being the high flexion period. When descending stairs, the low flexion period ranges from 0% to 50% and from 90% to 100%, with the rest being the high flexion period.

[0059] During the low flexion phase of the downhill movement: when 1:1.15 ≥ RFM:RTM ≥ 1:1.5, the medial displacement of a single-radius total knee joint prosthesis is significantly smaller than that of a multi-radius total knee joint prosthesis, resulting in greater stability. When the fit is less than 1:1.50, the medial displacement of a single-radius total knee joint prosthesis is relatively close to that of a multi-radius total knee joint prosthesis, meaning the medial displacement is larger. This is because during the low flexion phase of the downhill movement, a lower fit leads to insufficient stability in the fit between the medial condyle 210 and the medial articular surface 111 when the total knee joint prosthesis rotates around the medial condyle 210. Therefore, 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 ≥ RFM:RTM ≥ 1:1.5.

[0060] For example Figure 17 The motion curves of total knee prostheses with different fits and medial articular surfaces of a single radius during the downhill motion are shown. During the low flexion period of 0%-50% and 90%-100% of the motion cycle, when the fit is 1:1.15-1:1.5, the medial displacement of the total knee prosthesis with a single radius design is significantly lower than that with a multi-radius design, and the stability is more significant. As the fit gradually increases from 1:1.5 to 1:1.8, the medial displacement of the total knee prosthesis with a single radius design gradually approaches that of the total knee prosthesis with a multi-radius design.

[0061] It should be noted that the sagittal plane of the medial liner of a multi-radius design total knee prosthesis is composed of arc segments with multiple radii, and the fit is the ratio of the sagittal radius of the medial condyle to the sagittal radius at the distal (middle) end of the medial articular surface.

[0062] Further optionally, 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 is one of 1:1.15, 1:1.20, 1:1.25, 1:1.35, 1:1.45, or 1:1.50.

[0063] Furthermore, during the low flexion phase of the stair-climbing motion: when 1:1.15 ≥ RFM:RTM ≥ 1:1.5, the medial displacement of the single-radius total knee joint prosthesis is significantly smaller than that of the multi-radius total knee joint prosthesis, resulting in greater stability; when the fit is less than 1:1.50, the medial displacement of the single-radius total knee joint prosthesis is relatively close to that of the multi-radius total knee joint prosthesis, meaning the medial displacement is larger. This is because during the low flexion phase of the stair-climbing motion, a lower fit leads to insufficient stability in the fit between the medial condyle 210 and the medial articular surface 111 when the total knee joint prosthesis rotates around the medial condyle 210.

[0064] For example Figure 19 The motion curves of total knee prostheses with different fits and medial articular surfaces of a single radius during the uphill motion are shown. During the low flexion period of 0%-10% and 60%-100% of the motion cycle, when the fit is 1:1.15-1:1.5, the medial displacement of the total knee prosthesis with a single radius design is significantly lower than that with a multi-radius design, and the stability is more significant. As the fit gradually increases from 1:1.5 to 1:1.8, the medial displacement of the total knee prosthesis with a single radius design gradually approaches that of the total knee prosthesis with a multi-radius design.

[0065] Furthermore, the total knee joint prosthesis with a single radius design provided in this application significantly reduces wear compared to total knee joint prostheses with multi-radius designs in related technologies. This is because the higher fit between the medial articular surface and the medial condyle results in a larger contact area, effectively reducing wear on the total knee joint prosthesis and extending its service life. For example... Figure 20 As shown, in the embodiments of this application, during the variation of the medial fit of the total knee joint prosthesis from 1:1.15 to 1:1.8, the overall wear of the total knee joint prosthesis is less than that of the total knee joint prosthesis with a multi-radius design. Furthermore, as the fit gradually decreases towards 1:1.8, the wear of the total knee joint prosthesis tends to increase.

[0066] During daily activities, the medial and lateral condyles of the knee joint experience asymmetrical stress. For example, when a person stands up from a chair, the load on the medial condyle of the tibial pad is more than four times that on the lateral condyle. Similarly, when a person squats, the load on the medial condyle is more than eight times that on the lateral condyle. This necessitates an asymmetrical design for the medial and lateral condyles of the tibial pad. Therefore, in the design of the entire knee joint, while the knee joint rotates around its medial side, the medial condyle also needs a certain range of anterior-posterior displacement. Furthermore, the lateral condyle of the knee joint requires minimal restriction, and the lateral pad needs to have a suitable contour curve.

[0067] In this invention, the medial condyle 210 and the medial articular surface 111 of the tibial pad have a high degree of fit. In the sagittal plane, the medial articular surface 111 has a single radius with a small radius. Compared to the lateral articular surface 121, the medial articular surface 111 rises faster and more significantly at its lowest point in the sagittal plane, thereby limiting the anterior-posterior movement of the medial condyle 210 and facilitating the rotation of the total knee prosthesis around the medial side. Conversely, the lateral condyle 220 and the lateral articular surface 121 of the tibial pad have a lower degree of fit.

[0068] Figure 5 This is a BB cross-sectional view of a posteriorly stable knee joint prosthesis. Section BB is the lateral sagittal plane, corresponding to the range of the contact path during the mating process between the lateral articular surface 121 and the lateral condyle 220. Figure 11 This is a cross-sectional view of the posterior cruciate ligament replacement prosthesis (BB). The BB section is the lateral sagittal plane. Figure 5 and Figure 11 The distal surface of the middle lateral condyle 220 is constructed as a curved surface with a sagittal radius RFL.

[0069] The central structure of the lateral articular surface 121 is a curved surface with a sagittal radius of RTL, where 1:1.5 ≥ RFL:RTL ≥ 1:2.6. The central part of the lateral articular surface 121 refers to the portion that mates with the distal end of the lateral condyle 220. The lower fit between the lateral condyle 220 and the lateral articular surface 121 of the tibial pad facilitates a greater anteroposterior displacement of the lateral condyle 220 during flexion, thereby allowing the femoral prosthesis 200 to generate more external rotation relative to the tibial pad 100, which is more biomimetic.

[0070] Optionally, such as Figure 5 As shown, the lateral articular surface 121 is constructed as a curved surface with a sagittal radius of RTL, meaning that the cross-sectional lines formed by the intersection of the lateral articular surface 121 and the lateral sagittal surface are all circular arcs with a single sagittal radius RTL. Where 1:1.5≥RFL:RTL≥1:2.6.

[0071] Optionally, such as Figure 7 As shown, 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 surface comprises multiple sequentially connected arc segments, with adjacent arc segments having different sagittal radii. During knee flexion, the different sagittal radii of the lateral articular surface 121 can adjust the posterior displacement velocity of the lateral condyle 220, thereby adjusting the external rotation angle of the lateral condyle 220 at different flexion angles, making it more consistent with the natural state of the human knee joint.

[0072] exist Figure 7 In the illustrated embodiment, the outer articular surface 121 arc comprises three segments, with the sagittal radius of the middle arc being greater than the sagittal radius of each of the other two segments. Specifically, as... Figure 7As shown, the first arc segment in the anterior middle section has a first sagittal radius RTL1, the second arc segment in the middle and rear section has a second sagittal radius RTL2, and the third arc segment in the rear section has a third sagittal radius RTL3. The size of the second sagittal radius RTL2 of the second arc segment will affect the rotation angle of the lateral condyle 220 during moderate flexion. To accommodate different rotation angles of the lateral condyle 220, RTL2 can be made infinitely large, in which case the second arc segment approaches a straight line. In other embodiments, RTL2 can also be the same as RTL1 and RTL3. In this embodiment, 1:1.5 ≥ RTL:RTL1 ≥ 1:2.6.

[0073] Optionally, such as Figure 11 As shown, the lateral articular surface is constructed as a curved surface with a sagittal radius of RTL, meaning that the cross-sectional lines formed by the intersection of the lateral articular surface 121 and the lateral sagittal surface are all arcs with a single sagittal radius RTL. Where 1:1.5≥RFL:RTL≥1:2.6. The lower fit between the lateral condyle 220 and the lateral articular surface 121 of the tibial pad facilitates greater anterior-posterior displacement of the lateral condyle 220 during flexion, thereby allowing the femoral prosthesis 200 to generate more external rotation relative to the tibial pad 100, which is more in line with biomimetic structures.

[0074] Optionally, such as Figure 13 As shown, 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 surface comprises multiple sequentially connected arc segments, with different sagittal radii for adjacent arc segments. During knee flexion, the different sagittal radii of the lateral articular surface 121 can adjust the posterior displacement velocity of the lateral condyle 220, thereby adjusting the external rotation angle of the lateral condyle 220 at different flexion angles, making it more consistent with the natural state of the human knee joint.

[0075] exist Figure 13 In the illustrated embodiment, the outer articular surface 121 arc comprises three segments, with the sagittal radius of the middle arc being greater than the sagittal radius of each of the other two segments. Specifically, as... Figure 13 As shown, the first arc segment in the front middle section has a first sagittal radius RTL1, the second arc segment in the middle and rear section has a second sagittal radius RTL2, and the third arc segment in the rear section has a third sagittal radius RTL3. The size of the second sagittal radius RTL2 of the second arc segment will affect the rotation angle of the lateral condyle 220 during moderate flexion. To accommodate different rotation angles of the lateral condyle 220, RTL2 can be made infinitely large, in which case the second arc segment approaches a straight line. In other embodiments, RTL2 can be the same as RTL1 and RTL3. In this embodiment, 1:1.5 ≥ RTL:RTL1 ≥ 1:2.6. Alternatively, in other embodiments, RTL2 can be smaller than RTL1 or smaller than RTL3 depending on the actual situation; this embodiment is not limited to this.

[0076] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0077] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0078] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0079] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0080] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0081] 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. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A total knee prosthesis, characterized in that Comprise: A tibial pad including a medial articular surface and a lateral articular surface, and a femoral prosthesis including a medial condyle cooperating with the medial articular surface and a lateral condyle cooperating with the lateral articular surface, the medial articular surface is configured as a curved surface with a sagittal radius RTM, and a distal surface of the medial condyle is configured as a curved surface with a sagittal radius RFM that is congruent with the medial articular surface, wherein 1:1.1≥RFM:RTM≥1:1.8; A cross-section line formed by the intersection of the medial articular surface and a sagittal plane is a circular arc with a single sagittal radius; A distal surface of the lateral condyle is configured as a curved surface with a sagittal radius RFL, and a length of forward and backward displacement of the medial condyle during flexion movement is less than a length of forward and backward displacement of the lateral condyle; A cross-section line formed by the intersection of the lateral articular surface and a sagittal plane includes a plurality of circular arcs connected in sequence, and sagittal radii of adjacent two of the circular arcs are different.

2. The total knee prosthesis of claim 1, wherein, A 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≥RFM:RTM≥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 one of 1:1.15, 1:1.20, 1:1.25, 1:1.35, 1:1.45, and 1:1.

50.

4. The total knee prosthesis of claim 1, wherein, A middle portion of the lateral articular surface is configured as a curved surface with a sagittal radius RTL, wherein 1:1.5≥RFL:RTL≥1:2.

6.

5. The total knee prosthesis of claim 1, wherein, The lateral articular surface is configured as a curved surface with a sagittal radius RTL.

6. The total knee prosthesis of any of claims 1-5, wherein, The total knee prosthesis is a posterior cruciate ligament-retaining prosthesis or a posterior cruciate ligament-replacing prosthesis.

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