shin pads

Abstract

The present invention relates to a tibial liner. The tibial liner includes a medial articular surface and a lateral articular surface. The cross-sectional line formed by the intersection of the medial articular surface and a first sagittal plane includes a first arc, a first straight line segment, and a second arc connected in sequence. The radius of curvature of the first arc is greater than or equal to the radius of curvature of the second arc. The cross-sectional line formed by the intersection of the lateral articular surface and the second sagittal plane includes a fourth arc, a second straight line segment, and a fifth arc connected in sequence. The radius of curvature of the fourth arc is greater than or equal to the radius of curvature of the fifth arc. The tibial liner has good stability.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a tibial pad. Background Art

[0002] With the improvement of surgical techniques and the improvement of knee prostheses, total knee replacement surgery has become increasingly mature. Total knee replacement is an effective treatment for late-stage arthritis. With the continuous improvement of prostheses and the development of knee surgical techniques, total knee replacement has achieved better therapeutic results. However, traditional total knee replacement still has problems with postoperative "paradoxical anterior displacement" and knee flexion instability. "Paradoxical anterior displacement" means that after total knee replacement, during the patient's knee flexion, the femur moves forward relative to the tibia instead of moving backward in the normal state. "Paradoxical anterior displacement" and knee flexion instability can lead to problems such as increased stress on the patellofemoral joint surface and pain on the anterior side of the knee, which in turn leads to poor postoperative experience for patients and increases their postoperative pain. Summary of the Invention

[0003] Based on this, it is necessary to provide a tibial pad to improve the stability of the knee joint after total knee replacement.

[0004] The present application provides a tibial liner, comprising:

[0005] a medial articular surface, wherein a cross-sectional line formed by the intersection of the medial articular surface and the first sagittal plane includes a first circular arc, a first straight line segment, and a second circular arc connected in sequence, the radius of curvature of the first circular arc being greater than or equal to the radius of curvature of the second circular arc, and,

[0006] The lateral articular surface, the cross-sectional line formed by the intersection of the lateral articular surface and the second sagittal plane includes a fourth arc, a second straight line segment and a fifth arc connected in sequence; the curvature radius of the fourth arc is greater than or equal to the curvature radius of the fifth arc.

[0007] The technical solution of this application is further described below:

[0008] In one embodiment, the cross-sectional line formed by the intersection of the medial articular surface and the first coronal plane includes a third arc, and the curvature radius of the third arc is equal to the curvature radius of the first arc; and / or, the cross-sectional line formed by the intersection of the lateral articular surface and the second coronal plane includes a sixth arc; the curvature radius of the sixth arc is equal to the curvature radius of the fourth arc.

[0009] In one embodiment, the length of the first straight line segment ranges from 0.1 mm to 3 mm; and / or the length of the second straight line segment ranges from 9 mm to 14 mm.

[0010] In one embodiment, the distance from the medial edge to the lateral edge of the tibial liner is a first distance, and the tibial liner has a central sagittal plane for defining the medial articular surface and the lateral articular surface;

[0011] The distance from the first straight line segment to the central sagittal plane is a second distance, and the ratio of the second distance to the first distance is in the range of 0.25-0.35; and / or, the distance from the second straight line segment to the central sagittal plane is a third distance, and the ratio of the third distance to the first distance is in the range of 0.25-0.35.

[0012] In one embodiment, the distance from the anterior edge to the posterior edge of the medial articular surface is the fourth distance; the distance from the midpoint of the first straight line segment to the posterior edge of the medial articular surface is the fifth distance, and the ratio of the fifth distance to the fourth distance is in the range of 0.3-0.5; and / or, the distance from the anterior edge to the posterior edge of the lateral articular surface is the sixth distance; the distance from the midpoint of the second straight line segment to the posterior edge of the lateral articular surface is the seventh distance, and the ratio of the seventh distance to the sixth distance is in the range of 0.3-0.5.

[0013] In one embodiment, the vertical distance from the endpoint of the first arc at the anterior edge of the medial articular surface to the first straight line segment is 6mm-13mm; and / or the vertical distance from the endpoint of the second arc at the posterior edge of the medial articular surface to the first straight line segment is 0.2mm-4mm.

[0014] In one embodiment, the vertical distance from the endpoint of the fourth arc at the anterior edge of the lateral articular surface to the second straight line segment is 3mm-7mm; and / or, the vertical distance from the endpoint of the fifth arc at the posterior edge of the lateral articular surface to the second straight line segment is 0.2mm-3mm.

[0015] In one embodiment, the tibial pad also includes a convex surface connecting the medial articular surface and the lateral articular surface, the cross-sectional line formed by the convex surface and the third coronal plane includes a seventh arc, the cross-sectional line formed by the medial articular surface and the third coronal plane includes an eighth arc, the cross-sectional line formed by the intersection of the lateral articular surface and the third coronal plane includes a ninth arc, the seventh arc is tangent to the eighth arc, and the seventh arc is tangent to the ninth arc.

[0016] In one embodiment, the curvature radius of the seventh arc ranges from 35 mm to 50 mm.

[0017] In one embodiment, the medial articular surface has a first load-bearing midline in the cross section, and the first load-bearing midline includes a third straight line segment, a tenth circular arc and a fourth straight line segment connected in sequence; the tenth circular arc is tangent to the third straight line segment and the fourth straight line segment respectively.

[0018] In one embodiment, the distance from the medial edge to the lateral edge of the tibial liner is a first distance, the tibial liner has a central sagittal plane for defining the medial articular surface and the lateral articular surface, and the distance from the anterior edge to the posterior edge of the medial articular surface is a fourth distance; the intersection of the extended line of the third straight line segment and the extended line of the fourth straight line segment is a first intersection point,

[0019] The distance from the first intersection to the posterior edge of the medial articular surface is the eighth distance, and the ratio of the eighth distance to the fourth distance is in the range of 0.35-0.45; and / or, the distance from the first intersection to the central sagittal plane is the ninth distance, and the ratio of the ninth distance to the first distance is 0.25-0.3.

[0020] In one embodiment, the tibial liner has a central sagittal plane for defining the medial articular surface and the lateral articular surface, and the fourth straight line is parallel to the central sagittal plane.

[0021] In one embodiment, the tibial liner has a central sagittal plane for defining the medial articular surface and the lateral articular surface, and the angle between the third straight line segment and the central sagittal plane is in the range of 20°-25°.

[0022] In one embodiment, the lateral articular surface has a second load-bearing midline in the cross section, and the second load-bearing midline includes a fifth straight line segment and an eleventh circular arc connected in sequence; the eleventh circular arc is tangent to the fifth straight line segment.

[0023] In one embodiment, the distance from the medial edge to the lateral edge of the tibial liner is a first distance, the tibial liner has a central sagittal plane for defining the medial articular surface and the lateral articular surface, the distance from the anterior edge to the posterior edge of the lateral articular surface is a sixth distance; the tangent point of the eleventh circular arc and the fifth straight line segment is a third tangent point;

[0024] The distance from the third tangent point to the posterior edge of the lateral articular surface is the tenth distance, and the ratio of the tenth distance to the sixth distance is in the range of 0.35-0.45; and / or, the distance from the third tangent point to the central sagittal plane is the eleventh distance, and the ratio of the eleventh distance to the first distance is 0.25-0.3.

[0025] In one embodiment, the curvature radius of the eleventh arc ranges from 35 mm to 50 mm.

[0026] In one embodiment, the tibial liner has a central sagittal plane for defining the medial articular surface and the lateral articular surface, and the angle between the fifth straight line segment and the central sagittal plane is in the range of 10°-12°.

[0027] The tibial liner improves the rotational stability of the knee prosthesis by designing the medial and lateral articular surfaces in a ball-and-socket configuration. Furthermore, the intersection of the medial and lateral articular surfaces with the sagittal plane is designed as a straight line, increasing the tolerance of the knee prosthesis during surgery. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 is a schematic structural diagram of a tibial liner according to an embodiment;

[0031] Figure 2 A top view of a tibial pad according to an embodiment Figure 1 ;

[0032] Figure 3 for Figure 2 A cross-sectional view of the tibial liner at section AA shown in FIG;

[0033] Figure 4 for Figure 2 A cross-sectional view of the tibial liner shown in FIG. 1 at section BB;

[0034] Figure 5 A top view of a tibial pad according to an embodiment Figure 2 ;

[0035] Figure 6 for Figure 5 A cross-sectional view of the tibial liner at section DD shown in FIG;

[0036] Figure 7 for Figure 5 A cross-sectional view of the tibial liner shown in FIG.

[0037] Figure 8 A top view of a tibial pad according to an embodiment Figure 3 ;

[0038] Figure 9 for Figure 8 A cross-sectional view of the tibial liner shown in FIG. 1 at section EE;

[0039] Figure 10 A top view of a tibial pad according to an embodiment Figure 4 ;

[0040] Figure 11 A schematic structural diagram of a femoral condyle prosthesis is shown.

[0041] Description of reference numerals:

[0042] 10. Tibial liner; 11. Medial articular surface; L111. First distance; L112. Second distance; L113. Fourth distance; L114. Fifth distance; L115. First straight line segment; L116. Eighth distance; L117. Ninth distance; R111. First arc; R112. Second arc; R113. Third arc; R114. Tenth arc; 12. Lateral articular surface; L122. Third distance; L12 3. Sixth distance; L124, seventh distance; L125, second straight line segment; L127, eleventh distance; L128, tenth distance; R121, fourth arc; R122, fifth arc; R123, sixth arc; R124, eleventh arc; 13. Central sagittal plane; 14. Convex surface; R141, seventh arc; 20. Tibial condyle prosthesis; 21. AP line; 22. Medial condyle articular surface; 23. Lateral condyle articular surface. DETAILED DESCRIPTION

[0043] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0044] In order to better illustrate the technical solutions involved in the present invention, the directional nouns involved in each implementation scheme are first explained.

[0045] Sagittal plane: The section formed by cutting the human body or joint into two parts longitudinally;

[0046] Coronal plane: A plane that divides the human body or joint into two parts, front and back, and is perpendicular to the sagittal plane;

[0047] Cross-section: A section that divides the body or joint into upper and lower parts, perpendicular to the coronal and sagittal planes;

[0048] Distal: The end of the body or joint that is relatively farthest from the head;

[0049] Proximal: The end of the body or joint that is relatively close to the head;

[0050] Medial: relatively close to the sagittal plane of the human body;

[0051] Lateral: relatively deviated from the sagittal plane of the human body;

[0052] Anterior side: the side closest to the chest in the sagittal plane;

[0053] Posterior: the side close to the back in the sagittal plane;

[0054] AP direction: the direction from anterior to posterior in the sagittal plane;

[0055] PA direction: direction from posterior to anterior in the sagittal plane;

[0056] ML direction: the direction from the inner side to the outer side on the crown surface;

[0057] LM direction: direction from lateral to medial in the coronal plane.

[0058] Specifically, see Figure 1 One embodiment of the present application provides a tibial pad 10, which is used to be fixed to the proximal end of the tibia that has undergone osteotomy or to be fixed to a tibial support prosthesis. Furthermore, the tibial pad 10 is divided into a left-leg tibial pad 10 suitable for the left leg and a right-leg tibial pad 10 suitable for the right leg. The left-leg tibial pad 10 and the right-leg tibial pad 10 are mirror-symmetrical about the sagittal plane. In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the left-leg tibial pad 10 suitable for the left leg is used as an example for detailed description. Specifically, the tibial pad 10 of one embodiment includes a medial articular surface 11 and a lateral articular surface 12. The medial articular surface 11 is used to replace the medial meniscus of the tibia, and the lateral articular surface 12 is used to replace the lateral meniscus of the tibia.

[0059] Specifically, see Figure 2-4 The cross-sectional line formed by the intersection of the medial articular surface 11 and the first sagittal plane includes a first arc R111, a first straight line segment L115, and a second arc R112, which are sequentially connected from the front to the back. The radius of curvature of the first arc R111 is greater than or equal to the radius of curvature of the second arc R112. Preferably, the radius of curvature of the first arc R111 is equal to the radius of curvature of the second arc R112. Furthermore, the cross-sectional line formed by the intersection of the medial articular surface 11 and the first coronal plane includes a third arc R113, and the radius of curvature of the third arc R113 is equal to the radius of curvature of the first arc R111.

[0060] The tibial liner 10 is constructed by configuring the intersection of the medial articular surface 11 and the first sagittal plane as a first arc R111, a first straight line segment L115, and a second arc R112, which are connected in sequence. The intersection of the medial articular surface 11 and the first coronal plane is configured as a third arc R113. The radius of curvature of the first arc R111 is greater than or equal to that of the second arc R112, and the radius of curvature of the third arc R113 is equal to that of the first arc R111. This ensures that the medial articular surface 11 forms a ball-and-socket shape, further enhancing the rotational stability of the knee prosthesis. Furthermore, the first straight line segment L115 is used at some intersections of the medial articular surface 11 and the sagittal plane, increasing the tolerance of the knee prosthesis during surgery.

[0061] Specifically, the first sagittal plane is Figure 2 Section AA along line AA corresponds to the contact path between the medial articular surface 11 and the femoral condyle during the process of mating. Specifically, the tibial liner 10 has a central sagittal plane 13 that defines the medial articular surface 11 and the lateral articular surface 12. The central sagittal plane 13 refers to the sagittal plane passing through the inner and outer centerlines of the tibial liner 10, and the inner and outer centerlines of the tibial liner 10 refer to the straight line that divides the tibial liner 10 into two equal parts. Here, "equal division" refers to dividing the transverse length of the tibial liner 10 into equal parts. The distance from the medial edge to the lateral edge of the tibial liner 10 is recorded as the first distance L111, and the distance from the first sagittal plane to the central sagittal plane 13 of the tibial liner 10 (i.e., the distance from the first straight line segment L115 to the central sagittal plane 13) is recorded as the second distance L112. The ratio of the second distance L112 to the first distance L111 is in the range of 0.25-0.35.

[0062] Continue to see Figure 2 The first coronal plane is section BB. Preferably, the first coronal plane passes through the midpoint a of the first straight line segment L115. Specifically, the distance from the anterior edge to the posterior edge of the medial articular surface 11 is a fourth distance L113; the distance from the midpoint a of the first straight line segment L115 to the posterior edge of the medial articular surface 11 (i.e., the distance from the first coronal plane to the posterior edge of the medial articular surface 11) is a fifth distance L114. The ratio of the fifth distance L114 to the fourth distance L113 is in the range of 0.3-0.5, preferably 0.35-0.45.

[0063] The midpoint a of the first straight line segment L115 is the center position of the medial load-bearing area of ​​the natural knee joint in the extended position. The midpoint position of the first straight line segment L115 is limited by the ratio range of the second distance L112 to the first distance L111 and the ratio range of the fifth distance L114 to the fourth distance L113, thereby limiting the contact position of the femoral component and the tibial pad 10 prosthesis in the extended position, thereby avoiding excessive looseness or excessive tightness in the extension and flexion gaps of the knee joint after surgery.

[0064] Furthermore, the length of the first straight line segment L115 ranges from 0.1 mm to 3 mm, preferably from 0.5 mm to 1.5 mm. This design can improve the installation tolerance of the medial articular surface 11 during knee joint surgery and provide a natural knee joint motion area.

[0065] See also Figure 3 The vertical distance H111 from the endpoint of the first arc R111 at the anterior edge of the medial articular surface 11 (i.e., the intersection of the anterior edge and the first sagittal plane) to the first straight line segment L115 (i.e., the height of the anterior lip of the medial articular surface 11) is 6 mm to 13 mm, preferably 8 mm to 12 mm, thereby ensuring the stability of the medial articular surface 11 in the PA direction and preventing the patella from colliding with the anterior edge of the tibial liner 10 during high knee flexion. And / or, the vertical distance H112 from the endpoint of the second arc R112 at the posterior edge of the medial articular surface 11 (i.e., the intersection of the posterior edge and the first sagittal plane) to the first straight line segment L115 (i.e., the height of the posterior lip of the medial articular surface 11) is 0.2 mm to 4 mm, preferably 0.5 mm to 3 mm, thereby ensuring the stability of the medial articular surface 11 in the AP direction and solving the problem of difficulty in implanting the tibial liner 10 into the human body during knee replacement.

[0066] Specifically, see Figure 5-7 The cross-sectional line formed by the intersection of the lateral articular surface 12 and the second sagittal plane includes a fourth arc R121, a second straight line segment L125, and a fifth arc R122, which are sequentially connected from the front to the back. The radius of curvature of the fourth arc R121 is greater than or equal to the radius of curvature of the fifth arc R122. Preferably, the radius of curvature of the fourth arc R121 is equal to the radius of curvature of the fifth arc R122. Furthermore, the cross-sectional line formed by the intersection of the lateral articular surface 12 and the second coronal plane includes a sixth arc R123, and the radius of curvature of the sixth arc R123 is equal to the radius of curvature of the fourth arc R121.

[0067] The tibial liner 10 is constructed by configuring the intersection of the lateral articular surface 12 and the second sagittal plane as a fourth arc R121, a second straight line segment L125, and a fifth arc R122, which are connected in sequence. The intersection of the lateral articular surface 12 and the second coronal plane is configured as a sixth arc R123. The radius of curvature of the fourth arc R121 is greater than or equal to that of the fifth arc R122, and the radius of curvature of the sixth arc R123 is equal to that of the fourth arc R121. This ensures that the lateral articular surface 12 forms a ball-and-socket shape, further enhancing the rotational stability of the knee prosthesis. Furthermore, the second straight line segment L125 is used for some of the intersections of the lateral articular surface 12 and the sagittal plane, increasing the tolerance of the knee prosthesis during surgery.

[0068] Specifically, the second sagittal plane is Figure 5 The location of the median section DD corresponds to the range of the contact path between the lateral articular surface 12 and the femoral condyle during the mating process. Specifically, the distance from the second sagittal plane to the central sagittal plane 13 of the tibial liner 10 (i.e., the distance from the second straight line segment L125 to the central sagittal plane 13) is denoted as the third distance L122. The ratio of the third distance L122 to the first distance L111 is in the range of 0.25-0.35.

[0069] Continue to see Figure 5 The second coronal plane is section CC. Preferably, the second coronal plane passes through the midpoint b of the second straight line segment L125. Specifically, the distance from the anterior edge to the posterior edge of the lateral articular surface 12 is the sixth distance L123; the distance from the midpoint b of the second straight line segment L125 to the posterior edge of the lateral articular surface 12 (i.e., the distance from the second coronal plane to the posterior edge of the lateral articular surface 12) is the seventh distance L124. The ratio of the seventh distance L124 to the sixth distance L123 is in the range of 0.3-0.5, preferably 0.35-0.45. Preferably, the second coronal plane coincides with the first coronal plane.

[0070] The midpoint b of the second straight line segment L125 is the center position of the medial load-bearing area of ​​the natural knee joint in the extended position. The position of the midpoint b of the second straight line segment L125 is limited by the ratio range of the third distance L122 to the first distance L111 and the ratio range of the seventh distance L124 to the sixth distance L123, thereby limiting the contact position of the femoral component and the tibial pad 10 prosthesis in the extended position, thereby avoiding excessive looseness or tightness in the extension and flexion gaps of the knee joint after surgery.

[0071] Furthermore, the length of the second straight segment L125 ranges from 9 mm to 14 mm, preferably from 10 mm to 12 mm. This design can improve the installation tolerance of the lateral articular surface 12 during knee joint surgery and provide a natural knee joint motion area.

[0072] See also Figure 6 The vertical distance H121 from the endpoint of the fourth arc R121 at the anterior edge of the lateral articular surface 12 (i.e., the intersection of the anterior edge and the second sagittal plane) to the second straight line segment L125 (i.e., the height of the anterior lip of the lateral articular surface 12) is 3 mm to 7 mm, preferably 4 mm to 6 mm, thereby ensuring the stability of the lateral articular surface 12 in the PA direction and preventing the patella from colliding with the anterior edge of the tibial liner 10 during high flexion of the knee joint. And / or, the vertical distance H122 from the endpoint of the fifth arc R122 at the posterior edge of the lateral articular surface 12 (i.e., the intersection of the posterior edge and the second sagittal plane) to the second straight line segment L125 (i.e., the height of the posterior lip of the lateral articular surface 12) is 0.2 mm to 3 mm, preferably 0.5 mm to 2.5 mm, thereby ensuring the stability of the lateral articular surface 12 in the AP direction and solving the problem of difficulty in implanting the tibial liner 10 into the human body during knee replacement.

[0073] See also Figure 8-9 The tibial liner 10 further includes a convex surface 14 connecting the medial articular surface 11 and the lateral articular surface 12. The cross-sectional line formed by the convex surface 14 and the third coronal plane includes a seventh arc R141. The cross-sectional line formed by the medial articular surface 11 and the third coronal plane includes an eighth arc. The cross-sectional line formed by the intersection of the lateral articular surface 12 and the third coronal plane includes a ninth arc. The seventh arc R141 is tangent to the eighth arc, and the seventh arc R141 is tangent to the ninth arc. Preferably, see Figure 9 , the third coronal plane coincides with the second coronal plane and the first coronal plane. At this time, the eighth arc is the third arc R113, and the ninth arc is the sixth arc R123.

[0074] Furthermore, the radius of curvature of the seventh arc R141 ranges from 35 mm to 50 mm. If the radius of curvature of the seventh arc R141 is too large, the stability of the tibial liner 10 in the ML and LM directions will be poor. If the radius of curvature of the seventh arc R141 is too small, the tibial liner 10 will be difficult to implant into the human body. By setting the radius of curvature of the seventh arc R141 to 35 mm to 50 mm, the stability of the tibial liner 10 in the ML and LM directions is ensured, while also facilitating implantation of the tibial liner 10 into the human body by the surgeon.

[0075] Furthermore, natural knee joint motion involves rotation about the medial meniscus, and the medial femoral condyle midline is not parallel to the AP line 21, nor is the lateral femoral condyle midline. Therefore, the design of the medial articular surface 11 and the lateral articular surface 12 of the tibial liner 10 requires consideration not only of how to guide the femoral condyle's rotation but also of the oscillation design of the tibial liner 10 at the front end of the articular surface, so as to achieve better matching and contact area between the articular surfaces of the tibial liner 10 in both the extension and hyperextension positions.

[0076] See also Figure 10 , the medial articular surface 11 has a first load-bearing midline in the cross section. Specifically, the first load-bearing midline refers to the set of points where the femoral condyle prosthesis and the medial articular surface 11 of the tibial pad 10 contact each other during flexion, that is, the trajectory of the femoral condyle prosthesis moving on the medial articular surface 11 of the tibial pad 10 during knee flexion. Furthermore, the point on the first load-bearing midline is the most concave point (lowest point) of the medial articular surface 11 on the coronal plane. Specifically, in this embodiment, the first load-bearing midline includes a third straight line segment FM, a tenth circular arc R114, and a fourth straight line segment NG connected in sequence. The tenth circular arc R114 is tangent to the third straight line segment FM and the fourth straight line segment NG, respectively.

[0077] Furthermore, the intersection of the extension line of the third straight line segment FM and the extension line of the fourth straight line segment NG is the first intersection point P, the distance from the first intersection point P to the posterior edge of the medial articular surface 11 is the eighth distance L116, the ratio of the eighth distance L116 to the fourth distance L113 is in the range of 0.35-0.45, and / or, the distance from the first intersection point P to the central sagittal plane 13 is recorded as the ninth distance L117, and the ratio of the ninth distance L117 to the first distance L111 is 0.25-0.3.

[0078] Furthermore, the fourth straight line segment NG is parallel to the central sagittal plane 13. Furthermore, the angle α111 between the third straight line segment FM and the central sagittal plane 13 is in the range of 20°-25°. This can achieve better fit and contact area between the femoral condyle prosthesis and the tibial liner 10 during the process from hyperextension to extension, uniformly stressing the tibial liner 10 and improving the service life of the tibia.

[0079] See also Figure 10 , the lateral articular surface 12 has a second load-bearing midline in cross section. Similarly, the second load-bearing midline refers to the set of points where the femoral condyle prosthesis contacts the lateral articular surface 12 of the tibial liner 10 during flexion, that is, the trajectory of the femoral condyle prosthesis moving on the lateral articular surface 12 of the tibial liner 10 during knee flexion. Furthermore, the point on the first load-bearing midline is the most concave point (lowest point) of the medial articular surface 11 on the coronal plane. Specifically, in this embodiment, the second load-bearing midline includes the fifth straight line segment CD and the eleventh circular arc R124 connected in sequence, and the eleventh circular arc R124 is tangent to the fifth straight line segment CD.

[0080] Furthermore, the tangent point of the eleventh arc R124 and the fifth straight line segment CD is designated as the third tangent point D. The distance from the third tangent point D to the posterior edge of the lateral articular surface 12 is designated as the tenth distance L128. The ratio of the tenth distance L128 to the sixth distance L123 is in the range of 0.35-0.45. Alternatively, the distance from the third tangent point D to the central sagittal plane 13 is designated as the eleventh distance L127. The ratio of the eleventh distance L127 to the first distance L111 is in the range of 0.25-0.3. Furthermore, the radius of curvature of the eleventh arc R124 is in the range of 35 mm-50 mm, and the angle α121 between the fifth straight line segment CD and the central sagittal plane 13 is in the range of 10°-12°. This design ensures better fit and contact area between the femoral condyle prosthesis and the tibial liner 10 from hyperextension to extension, evenly distributes force on the tibial liner 10, and improves the service life of the tibia.

[0081] Furthermore, in order to further illustrate in detail how the front end swing design of the tibial pad 10 improves the compatibility and contact area of ​​the knee joint prosthesis in the extension and hyperextension positions, the femoral condyle prosthesis is introduced here. The femoral condyle prosthesis is used to be fixed to the distal femur that has been prepared for surgery to replace the articular surface of the distal femur. Figure 11 The femoral condyle prosthesis includes a medial condyle articular surface 22 and a lateral condyle articular surface 23. The spherical radius of the medial condyle articular surface 22 is SR22, and the value of the spherical radius SR22 is 0.5mm-1mm smaller than the curvature radius of the third arc R113. The spherical radius of the lateral condyle articular surface 23 is SR23, and the value of the spherical radius SR23 is 0.5mm-1mm smaller than the curvature radius of the sixth arc R123. The swing head of the medial condyle articular surface 22 at the front end is α22, and the value of α22 is equal to the value of α111. The swing head of the lateral condyle articular surface 23 at the front end is α23, and the value of α23 is equal to the value of α121. The "swing head" here refers to the fact that the weight-bearing midline of the front end of the femoral condyle or the weight-bearing midline of the tibial pad 10 prosthesis forms a certain angle with the sagittal plane.

[0082] By designing the angle between the third straight segment and the central sagittal plane 13, as well as the angle between the fifth straight segment CD and the central sagittal plane 13, the femoral condyle prosthesis and the tibial pad 10 can obtain good assembly and contact area from hyperextension to extension, so that the tibial pad 10 is evenly stressed, thereby improving the service life of the tibial pad 10.

[0083] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0084] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

[0085] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0086] 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 the technical features being referred to. 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, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0087] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0088] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0089] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

Claims

1. A tibial pad, characterized in that: include: a medial articular surface, wherein a cross-sectional line formed by the intersection of the medial articular surface and the first sagittal plane includes a first arc, a first straight line segment, and a second arc sequentially connected from the front side to the back side of the tibial liner, the radius of curvature of the first arc being greater than or equal to the radius of curvature of the second arc, and, a lateral articular surface, wherein a cross-sectional line formed by the intersection of the lateral articular surface and the second sagittal plane includes a fourth arc, a second straight line segment, and a fifth arc sequentially connected from the front side to the back side of the tibial liner; a radius of curvature of the fourth arc is greater than or equal to a radius of curvature of the fifth arc; The distance from the medial edge to the lateral edge of the tibial liner is a first distance, and the tibial liner has a central sagittal plane for defining the medial articular surface and the lateral articular surface; the distance from the first sagittal plane to the central sagittal plane is a second distance, and the ratio of the second distance to the first distance is in a range of 0.25-0.35; the distance from the second sagittal plane to the central sagittal plane is a third distance, and the ratio of the third distance to the first distance is in a range of 0.25-0.35; The length of the first straight line segment ranges from 0.1 mm to 3 mm; the length of the second straight line segment ranges from 9 mm to 14 mm; The distance from the anterior edge to the posterior edge of the medial articular surface is a fourth distance; the distance from the midpoint of the first straight line segment to the posterior edge of the medial articular surface is a fifth distance, and the ratio of the fifth distance to the fourth distance is in a range of 0.3-0.5; the distance from the anterior edge to the posterior edge of the lateral articular surface is a sixth distance; the distance from the midpoint of the second straight line segment to the posterior edge of the lateral articular surface is a seventh distance, and the ratio of the seventh distance to the sixth distance is in a range of 0.3-0.5; The vertical distance between the endpoint of the first arc at the front edge of the medial articular surface and the first straight line segment is 6 mm to 13 mm; the vertical distance between the endpoint of the second arc at the rear edge of the medial articular surface and the first straight line segment is 0.2 mm to 4 mm; The vertical distance between the endpoint of the fourth arc at the anterior edge of the lateral articular surface and the second straight line segment is 3 mm to 7 mm; the vertical distance between the endpoint of the fifth arc at the posterior edge of the lateral articular surface and the second straight line segment is 0.2 mm to 3 mm; The tibial liner further comprises a convex surface connecting the medial articular surface and the lateral articular surface, a cross-sectional line formed by the convex surface and the third coronal plane comprises a seventh circular arc, a cross-sectional line formed by the medial articular surface and the third coronal plane comprises an eighth circular arc, a cross-sectional line formed by the intersection of the lateral articular surface and the third coronal plane comprises a ninth circular arc, the seventh circular arc is tangent to the eighth circular arc, and the seventh circular arc is tangent to the ninth circular arc; The curvature radius of the seventh arc ranges from 35 mm to 50 mm; The cross-sectional line formed by the intersection of the medial articular surface and the first coronal plane includes a third arc, and the curvature radius of the third arc is equal to the curvature radius of the first arc; the cross-sectional line formed by the intersection of the lateral articular surface and the second coronal plane includes a sixth arc; the curvature radius of the sixth arc is equal to the curvature radius of the fourth arc.

2. The tibial liner according to claim 1, wherein The medial articular surface has a first load-bearing midline in the cross section, and the first load-bearing midline includes a third straight line segment, a tenth circular arc and a fourth straight line segment connected in sequence; the tenth circular arc is tangent to the third straight line segment and the fourth straight line segment respectively.

3. The tibial pad according to claim 2, wherein: The distance from the front edge to the back edge of the medial articular surface is a fourth distance; the intersection of the extension line of the third straight line segment and the extension line of the fourth straight line segment is a first intersection point, The distance from the first intersection to the posterior edge of the medial articular surface is the eighth distance, and the ratio of the eighth distance to the fourth distance is in the range of 0.35-0.45; and / or, the distance from the first intersection to the central sagittal plane is the ninth distance, and the ratio of the ninth distance to the first distance is 0.25-0.

3.

4. The tibial liner according to claim 2, wherein: The fourth straight line segment is parallel to the central sagittal plane.

5. The tibial liner according to claim 2, wherein: The included angle between the third straight line segment and the central sagittal plane is in the range of 20°-25°.

6. The tibial liner according to claim 1, wherein The lateral articular surface has a second load-bearing midline in the cross section, and the second load-bearing midline includes a fifth straight line segment and an eleventh circular arc connected in sequence; the eleventh circular arc is tangent to the fifth straight line segment.

7. The tibial liner according to claim 6, wherein: The distance from the medial edge to the lateral edge of the tibial liner is a first distance, the tibial liner has a central sagittal plane for defining the medial articular surface and the lateral articular surface, the distance from the anterior edge to the posterior edge of the lateral articular surface is a sixth distance; the tangent point of the eleventh circular arc and the fifth straight line segment is a third tangent point; The distance from the third tangent point to the posterior edge of the lateral articular surface is the tenth distance, and the ratio of the tenth distance to the sixth distance is in the range of 0.35-0.45; and / or, the distance from the third tangent point to the central sagittal plane is the eleventh distance, and the ratio of the eleventh distance to the first distance is 0.25-0.

3.

8. The tibial liner according to claim 7, wherein: The curvature radius of the eleventh arc ranges from 35 mm to 50 mm.

9. The tibial liner according to claim 7, wherein: The angle between the fifth straight line segment and the central sagittal plane is in the range of 10°-12°.

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