TIBIAL TRAY WITH A TIBIAL TRAY ROD STRUCTURE AND AN ARTIFICIAL KNEE JOINT

Abstract

The invention relates to a tibial tray (20) with a distal surface (D), wherein a tibial tray shaft structure (21) extends away from the distal surface (D) in the distal direction (DD), wherein the tibial tray structure (21) comprises at least three shaft wall elements (22, 23, 24, 25) which are so arranged relative to each other that the cross-sections of the at least three shaft wall elements (22, 23, 24, 25) in a plane perpendicular to the distal direction (DD) are at least sections T-shaped, Y-shaped or X-shaped and that the area (F) of the cross-sections decreases strictly monotonously from the distal surface (D) in the distal direction. The invention also relates to an artificial knee joint.

Description

[0001] The present invention relates to a tibial rod with a rod structure having the characteristics of claim 1 and an artificial knee joint with the characteristics of claim 27.

[0002] Joint replacements, in particular artificial knee joint replacements, have been known for quite some time. In the case of an artificial knee joint, it is known that a part of a tibial tray is connected to the proximal end of the patient's tibia. The connection is made through the distal part of the tibial tray, that is, the stem of the tibial tray.

[0003] A femoral part is connected to the distal end of the patient's femur. A tibial insert is connected to the proximal surface of the tibial tray so that after completion of the surgical procedure, the tibial insert is positioned between the distal surface of the femoral part and the proximal surface of the distal tray.

[0004] A tibial tray and a tibial insert of this type are described in EP 3 626 209 B1.

[0005] To ensure a good cemented connection between the proximal end of the tibia and the tibial tray stem, appropriately shaped geometries, such as form-fitting designs, are required. This is particularly important when a ceramic material is used for both the tibial tray and its tibial tray stem.

[0006] The tibial tray with the characteristics of claim 1 addresses these issues.

[0007] The tibial tray comprises a distal surface, wherein a tibial tray rod structure extends away from the distal surface in a distal direction. The tibial tray structure forms a protuberance, which is inserted into the tibial bone. Petition 870250082988, dated 09 / 15 / 2025, page 9 / 82 2 / 38

[0008] For good fixation of the tibial tray to the bone, the tibial tray structure comprises at least three rod wall elements that are arranged relative to each other so that the cross-sections of the at least three rod wall elements in a plane perpendicular to the distal direction are T-shaped, Y-shaped, or X-shaped. A T-shaped structure comprises three rod wall elements, two forming the T-bar, one forming the rod. The bar and rod are positioned at a 90° angle.

[0009] A Y-shaped structure also comprises three rod wall elements, but three angles may be different from 90°. In one possible embodiment, the rod wall elements are spaced equally by 120°. Alternatively, two rod wall elements may be spaced by 90°, the remaining third rod wall element is then spaced from the others by 135° each.

[0010] An X-shaped structure comprises four rod wall elements. The rod wall elements are positioned around a central axis, with angles between the rod wall elements. It is possible that, for example, each of the two sets of angles between the rod wall elements comprises angles of the same size (for example, two angles of 110° each, and two angles of 70° each).

[0011] Furthermore, the cross-sectional area decreases in a strictly uniform manner from the distal surface towards the distal direction. This means that the tibial tray structure generally tapers from a wide base towards the distal direction. This facilitates effective insertion of the tibial tray into the tibia. The tapering is continuous with sections parallel to the distal surface.

[0012] In one modality, the outer hoops of at least three Petition 870250082988, dated 09 / 15 / 2025, page 10 / 82 3 / 38 of the rod wall elements converge in a strictly uniform manner in the distal direction and toward an axis of the tibial tray structure. Again, this is an additional tapering aspect, facilitating effective insertion of the tibial tray into the tibia.

[0013] The shape of the outer rim could, for example, be curved with a uniform direction of curvature (e.g., an exponential shape). But the outer rims of at least three rod wall elements have in one embodiment at least one inflection point, in particular three inflection points. This means that the direction of curvature—not just the amount—changes at least once.

[0014] The curvature of the outer rim should not change too rapidly, such that any change in a tangent angle on an outer rim of at least three stem wall elements should be less than 30° over a 10% change in the distal direction, in particular any tangent angle of the outer rim of at least three stem wall elements within one-third of the height of the tibial tray structure measured from the distal surface. Changes in inclination should be smaller in the third of the tibial stem structure closest to the distal surface.

[0015] In an additional embodiment, at least 50% of the volume of the tibial tray structure is located within one third of the height of the tibial tray structure measured from the distal surface.

[0016] At least one of the rod wall elements may have a wall thickness between 1 and 6 mm, in particular 2 to 5 mm, for ceramic materials 1 and 5 mm, measured at the furthest point from the axis and on the distal surface.

[0017] It is also possible that the radius in the transition from the outer rim of at least one of the at least three rod wall elements to the side walls of at least one of the at least three elements Petition 870250082988, dated 09 / 15 / 2025, page 11 / 82 4 / 38 rod wall thickness is in the range of 0.5 to 4 mm.

[0018] For efficient bonding with bone cement, at least one of the at least three stem wall elements comprises at least one cement retention structure, in particular at least one recess structure for retaining bone cement. Those cement retention structures may preferably be positioned on the anterior and / or posterior side near the tibial tray.

[0019] The transition point from the outer rim to the tibial stem structure on the distal surface is located at least 5 mm from the lateral faces and / or the posterior side of the distal surface. This ensures adequate distance from the rim to the distal surface and ensures that the tibial stem structure is positioned within the spongy substance and outside the cortical substance. The distance is measured from the end of the outer rim in a straight line to the edge of the distal surface.

[0020] In one embodiment, the tibial tray structure comprises a surface extending between at least two of the outer rims of the at least three stem wall elements or between two side walls of the at least three stem wall elements.

[0021] As edge rounding may be relevant, the radius at the transition from the distal surface to at least one of the at least three stem wall elements and / or the smooth surface may be in the range of 1 to 4 mm.

[0022] Furthermore, it is possible that the axis of the tibial tray rod structure is located on the distal surface at one-third of the distance between the anterior rim and the posterior rim, measured from the anterior rim. This means that the axis of the tibial tray rod is located slightly more anteriorly than posteriorly. The axis of the tibial tray rod is defined by tray rod structures. Petition 870250082988, dated 09 / 15 / 2025, page 12 / 82 5 / 38 tibial deja in X, Y, and T shapes, as the three rod wall elements converge to this axis in a strictly uniform manner. In one specific embodiment, the distance from the axis of the tibial rod tray structure is 5 mm, 5.67 mm, 6.33 mm, or 7 mm from the center of the distal surface. In combination with this, or alternatively, the embodiments may have the tibial rod tray structures with a distal surface height of 35 mm, 40 mm, 45 mm, or 55 mm. In combination with this, or alternatively, the thickness of the rod wall elements may be 3 mm, 3.75 mm, 4.25 mm, or 5 mm.

[0023] The angle between the rod wall elements is between Angles of 90° and 180° on the anterior side and between 30° and 120° on the posterior side. For example, a T-shaped tibial tray structure with three rod wall elements would have an anterior angle of 180° and two 90° angles on the posterior side. X- and Y-shaped tibial tray structures could vary within the established regions.

[0024] To ensure a good mechanical connection between the tibial tray and the tibia, the tibial tray stem structure comprises at least one cement retention structure, in particular a hole, a groove and / or a recess without any cutout. This allows for efficient cement entry into the cement retention structures. In particular, the at least one cement retention structure is located within the vertical two-thirds of the tibial tray stem structure measured from the distal surface in the distal direction, in particular within the first third. This means that the at least one cement retention structure is preferably located in the direction of the distal surface and not in the direction of the distal end of the tibial tray stem structure.

[0025] In an additional embodiment, the tibial tray comprises Petition 870250082988, dated 09 / 15 / 2025, page 13 / 82 6 / 38 at least one anterior fixation element, in particular exactly one anterior fixation element, which is positioned on the anterior side of the proximal surface, the posterior side of the at least one anterior fixation element comprising a wall that in a plane parallel to the proximal surface is perpendicular to the medial plane of the proximal surface. In particular, the at least one anterior fixation element comprises at least one shaped fitting element, in particular, at least one cavity in the posterior wall of the at least one anterior fixation element and / or at least one channel through the at least one anterior fixation element, for a corresponding shaped fitting element of the tibial insertion, the at least one shaped fitting element of the at least one anterior fixation element being in particular positioned in a region where the load transfer is less than 70%, in particular 50% of the maximum load transfer.

[0026] The at least one anterior fixation element may comprise at least one guide surface for a tibial insert, in particular the guide surface having a curved and / or flat part, in a proximal direction of the at least one form fitting element. When the tibial insert is about to be fitted with the tibial tray, a protrusion of the tibial insert contacts the guide surface and slides along the guide surface so that its movement during fitting is guided and the protrusions can fit into the at least one form fitting element. In one embodiment, the at least one guide surface comprises a flat part or is a plane that is inclined with respect to the horizontal plane by an angle in the range of 5 to 45°, in particular 30°.

[0027] In some embodiments, the tibial tray comprises a proximal surface, the proximal surface comprising at least two, in particular exactly two central fixation elements. Petition 870250082988, dated 09 / 15 / 2025, p. 14 / 82 7 / 38 lateral to allow a connection with the tibial insertion as an additional part of an artificial knee joint, wherein at least two central fixation elements are proximal surface protrusions in the proximal direction and the at least two central fixation elements are positioned symmetrically and / or parallel to a medial plane of the proximal surface, the medial plane being perpendicular to the proximal surface and intersecting the proximal surface midway between two most lateral points of the proximal surface. In particular, the at least two central fixation elements are symmetrically positioned with respect to a frontal plane perpendicular to the medial plane, the frontal plane in particular passing through the most lateral points of the proximal surface. The at least two central fixation elements may comprise a central fixation element recess to provide a better fit with the tibial insertion.At least two, or exactly two, central fastening elements can be constructed as form-fitting and / or press-fitting elements.

[0028] Furthermore, it is possible that an embodiment of the tibial tray comprises at least one posterior fixation element, in particular exactly one, positioned symmetrically to the medial plane of the proximal surface comprising a posterior wall level with the posterior rim of the tibial tray and / or comprising an anterior wall that is essentially positioned parallel to the posterior wall of the at least one anterior fixation element. The lateral walls and / or the anterior wall of the at least one posterior element may in particular be inclined by an angle between 0 and 45°, in particular between 0 and 30°, more particularly by an angle of 10°, with respect to a plane that is perpendicular to the proximal plane and / or the lateral walls and the anterior wall of the at least one posterior element comprise a cutout. This allows, for example, the formation of a post block. Petition 870250082988, dated 09 / 15 / 2025, p. 15 / 82 8 / 38 posterior with side walls inclined inwards (i.e., side walls with an angle greater than 0°) and side walls converging towards the anterior side or a tongue and groove (cutout) system. Such a posterior fixation element can be used as a support point when attaching to a tibial insert.

[0029] The tibial tray can be manufactured entirely or partly from ceramic, a polymeric material or a metal.

[0030] Other embodiments of a tibial tray may comprise a proximal surface comprising at least two, in particular, exactly two central fixation elements to allow a connection with a tibial insertion as an additional part of an artificial knee joint. The central fixation elements are protrusions of the proximal surface, which may be connected as form-fitting and / or force-locking with the tibial insertion.

[0031] The at least two central fixation elements are designed as protrusions of the proximal surface in the proximal direction, i.e., the central fixation elements generally point away from the proximal surface in the direction of the tibial insertion.

[0032] The at least two central fixation elements are positioned symmetrically and / or parallel to a medial plane of the proximal surface, the medial plane being particular to the proximal surface and intersecting the proximal surface midway between two more lateral points of the proximal surface. The medial plane is dividing the proximal surface into two lateral halves. The at least two central fixation elements are oriented symmetrically and / or parallel to the medial plane. In a further embodiment, the at least two fixation elements are oriented asymmetrically with respect to the medial plane. This may imply different angles with respect to the medial plane and / or different distances from the medial plane.

[0033] The at least two central fastening elements are confi Petition 870250082988, dated 09 / 15 / 2025, page 16 / 82 9 / 38 shaped as cylindrical protrusions or linear protrusions, in particular designed for press-fit and / or form-fit. Cylindrical means that the protrusion has, for example, an elliptical or circular cross-section. Linear means that the protrusion extends linearly on the proximal surface. At least one of the central fastening elements may, for example, have a linear or cylindrical shape.

[0034] In one embodiment, the at least two central fixation elements are symmetrically positioned with respect to a frontal plane perpendicular to the medial plane. The frontal plane is dividing the proximal surface into an anterior and a posterior part. In particular, it is possible for the frontal plane to pass through most lateral points of the proximal surface.

[0035] For improved tibial insertion and improved fixation in vivo, the posterior wall of at least one anterior fixation element and / or the anterior wall of at least one posterior fixation element may comprise a cutout.

[0036] In one embodiment, the height of the at least two central fixation elements, the at least one anterior fixation element, and / or the at least one posterior fixation element extending from the proximal surface is in the range between 1 mm and 6 mm, in particular between 3 mm and 4 mm, 5 mm, and / or where the anterior and / or posterior ends of the at least two central fixation elements are rounded. In particular, the height of the at least two central fixation elements, the height of the at least one anterior fixation element, and / or the height of the at least one posterior fixation element above the proximal surface is constant or varies by a maximum of 10% of the minimum height. These features are instrumental in providing secure connection with the tibial insertion and / or enabling effective assembly.

[0037] The issues are also resolved by a tibial insertion Petition 870250082988, dated 09 / 15 / 2025, p. 17 / 82 10 / 38 designed or configured to match the tibial tray as claimed.

[0038] To ensure a good connection with the tibial tray, the tibial insertion may comprise a recess on the distal surface for the adaptation of at least one posterior fixation element, the recess comprising at least one stress-relieving notch at the junction of the two recess walls. This prevents the buildup of mechanical stress from sharp corners where two recess walls meet.

[0039] Secure connection may be enabled by at least one form fitting element of the tibial insert to engage at least one form fitting element of at least one anterior tibial tray fastening element. The connection may also be made with a press-fit connection or a combination thereof.

[0040] The issues are also resolved by an artificial knee joint comprising a claimed tibial tray and a claimed tibial insert, wherein there is a light press-fit connection between the tibial insert and at least two central fixation elements, at least one anterior fixation element and at least one posterior fixation element, in particular having a press-fit in the range of 0 to 450 μm, in particular in the range of 0 to 250 μm.

[0041] In an additional embodiment of an artificial knee joint, there is at least one pressure-fit region between the posterior fixation element and the tibial insertion, in particular created by an angular mismatch between two walls. This allows for improved joint assembly and a reduction of micromovements in the posterior parts of the joint.

[0042] Embodiments of the invention are shown in the figures: Figure 1 shows a perspective view of a joint. Petition 870250082988, dated 09 / 15 / 2025, page 18 / 82 11 / 38 artificial knee implant; Figure 2 shows a perspective view of the distal surface of a tibial tray embodiment with a tibial tray structure with three rod wall elements (Y-structure); Figure 3 shows a perspective view of the distal surface of a tibial tray embodiment with a tibial tray structure with four rod wall elements (structure X); Figure 4 shows a revision on the distal surface of an additional modality of a tibial tray with the tibial tray structure with three rod wall elements (T-structure); Figure 5 shows the structure of Figure 4 with a cross-sectional plane in the proximal third of the tibial tray structure (T-structure); Figure 6 shows a perspective view of the distal surface of the modality shown in Figures 4 and 5 (T-shaped structure); Figure 6A shows a view of the distal surface of a modality with ray indications around the perimeter; Figure 7 shows a perspective view of the side of one embodiment of a tibial tray with a tibial tray structure with three rod wall elements (T-structure) and a recess structure for a bone cement; Figure 8 shows a perspective view of the distal surface of a tibial tray embodiment with a tibial tray structure with three rod wall elements (T-structure); Figure 9 shows a perspective view of one embodiment of a tibial plate; Figure 9A shows the same view as Figure 9, highlighting reference frames; Figure 9B shows a variation of the modality in figure 9; Figure 10A shows a view of the proximal surface of a Petition 870250082988, dated 09 / 15 / 2025, page 19 / 82 12 / 38 tibial tray modality; Figure 10B shows a view of the distal surface of a tibial insertion corresponding with the tibial tray shown in Figure 10A; Figure 11 shows a view of a proximal surface of the modality shown in Figure 10A indicating regions of interference; Figure 12A shows the insertion of a tibial insert into a tibial tray from a perspective view; Figure 12B shows the tibial insertion in a tibial tray in Figure 12A from a sectional view; Figure 13A shows a detailed frontal view of an early tibial insertion modality; Figure 13B shows a detailed frontal view of a second tibial insertion modality; Figure 14 shows a perspective view of a variation of the modality shown in Figure 9; Figure 15A is a perspective view of the distal surface with a view from the anterior side of the tibial stem structure; Figure 15B is a perspective view of the distal surface with a view from the posterior side of the tibial stem structure; Figure 15C is a proximal view of the distal surface; Figure 16A is a perspective view of the posterior side of the proximal surface of the tibial tray with a first embodiment of central fixation elements; Figure 16B is a perspective view from the anterior side of the proximal surface of the tibial tray with the first modality of central fixation elements; Figure 17 is a perspective view of the posterior side of the proximal surface of the tibial plate with a second modality of Petition 870250082988, dated 09 / 15 / 2025, page 20 / 82 13 / 38 central fastening elements; Figure 18A is a cross-sectional view through a manifestation of the tibial plate in the anterior direction; Figure 18B shows a cross-sectional view through a manifestation of the tibial plate in the posterior direction; Figure 19 shows a schematic representation of line elements to generate a smooth outer rim for wall elements; Figure 20A shows a perspective view of the anterior side of a tibial tray embodiment with a cement retention structure; Figure 20B shows a perspective view of the back side of the modality shown in Figure 20A with a cement retention structure; Figure 21A shows a perspective view of the anterior side of a form with an illustration of the geometry in tibial tray rod structure wall elements; Figure 21B shows a perspective view of the rear side of the modality shown in Figure 21A; Figure 22 shows a perspective view on the proximal surface of an additional tibial tray design with guide surfaces on the anterior fixation element; Figure 23 shows a detail of the connection between the posterior fixation elements in a modality.

[0043] In Figure 1, an artificial knee joint 100 is shown in a perspective view from a posterior position. In Figure 1, a femoral part 40, a tibial insertion 30 and a tibial tray 20 of the metal-free artificial knee joint are shown. Alternative models are not metal-free.

[0044] Here, the complete artificial knee joint 100 is free Petition 870250082988, dated 09 / 15 / 2025, page 21 / 82 14 / 38 made of metal, for example, a combination of ceramic and polymeric materials. The tibial tray 20, for example, can be made of ceramic and the tibial insert 30 can be made of polymeric material.

[0045] In the proximal position of the artificial knee joint, a femoral part 40 is shown with two condyles fitting into the corresponding grooves on the proximal surface and a tibial insertion 30 at the distal end of the femoral part 40.

[0046] The tibial insert 30 is connected to a tibial tray 20, the distal surface D of the tibial insertion 30 facing the proximal surface P of the tibial tray 20.

[0047] In connection with figures 2 to 8, embodiments of a tibial tray 20 will be described. In figures 9 to 14, embodiments of the tibial tray 10 and a tibial insert 30 that can be used in connection within the embodiments of the tibial tray 20 described herein are described.

[0048] Figure 2 shows a perspective view of the distal side of an embodiment of a tibial tray 20. The shape of the distal surface D is roughly shaped like the proximal side of the tibial tray 20 (see, for example, Figures 9 to 15). A tibial tray rod structure 21 is located at the center of the distal surface D, i.e., midway across the lateral width between points L1 and L2. In the embodiment shown, the tibial tray structure 21 is essentially Y-shaped (i.e., referring to a cross-section in a plane parallel to the distal surface D) with an axis A at its center. The tibial tray structure 21 comprises three rod wall elements 22, 23, 24 which are placed around axis A at angles of 120° between them. One wall element of rod 22 of the Y is oriented towards the anterior side of the tibial tray 20, the other two wall elements 23, 24 are oriented towards the posterior side of the tibial tray 20.

[0049] The tibial tray structure 21 extends away from Petition 870250082988, dated 09 / 15 / 2025, page 22 / 82 15 / 38 distal surface D to a distal direction DD (as indicated, for example, in figure 5) which in figure 2 is essentially pointing out of the plane of the figure.

[0050] On the rim of the distal D surface there is a raised rim. R, extending away from the distal surface D. The width in the plane parallel to the distal surface D is between 1 and 4 mm.

[0051] The three rod wall elements 22, 23, 24 of the tibial tray rod structure 21 comprise outer rings 26. The outer rings 26 are thin faces of the rod wall elements 22, 23, 24. The thickness T of the rod wall elements 22, 23, 24 measured at the end points (i.e., the points furthest from the A axis on the distal surface D) is between 2 and 5 mm.

[0052] The outer rings 26 converge from their broad base on the distal surface D to the axis A in the distal direction. The convergence is strictly monotonic, i.e., there is no section of the outer rings 26 being parallel to the distal surface D. In the embodiment shown in Figure 2, the inclination of the outer rings 26 is increasing from the base, i.e., the distal surface D, in the direction of the axis. The change in inclination is smooth, without twists.

[0053] In the subtended space between the rod wall elements 22, 23, 24, the outer rings 26 are connected by a smooth surface S, here an internal curved surface (i.e., for axis A). The surface 13 itself has no folds or edges to allow for good insertion into the tibia. The transition from the smooth surface 13 to the outer ring 26 is also smooth, i.e., without folds or edges. In the embodiment shown, the radius R2 of this transition is between 1 and 4 mm, in particular depending on the size of the tibial tray structure 21.

[0054] The transition from the distal surface D to the stem wall elements 22, 23, 24 and / or the smooth wall 13 is rounded with the radius R1 being in the range of 1 to 4 mm. Petition 870250082988, dated 09 / 15 / 2025, page 23 / 82 16 / 38

[0055] As will also be shown in more detail in the context of Figure 5, the cross-sectional area of ​​the tibial stem structure 21 in a plane C parallel to the distal surface D is larger at the base on the distal surface D. The cross-sectional area becomes smaller (in particular, in a strictly monotonically smaller way) as the tibial stem structure 21 extends in the distal direction DD.

[0056] The base plate with distal surface D has a thickness in the range of 2 mm to 6 mm, in particular 4.5 mm.

[0057] Figure 3 shows an embodiment of a tibial tray 20 comprising four rod wall elements 22, 23, 24, 25 in an X-shaped pattern. Two of the rod wall elements 24, 25 are oriented towards the anterior side of the tibial tray 20, two of the rod wall elements 22, 23 are oriented towards the posterior side.

[0058] Furthermore, the geometry of the outer rings 26, the smooth surface 13 in the angled space between the rod wall elements 22, 23, 24, 25, and in particular the convergence of the outer rings 26 in the distal direction DD to the axis A, are analogous to the embodiment shown in connection with figure 2, so that reference can be made to the description.

[0059] The embodiment shown in Figure 4 in a perspective view is a further variation of the embodiment shown in Figures 2 and 3. Therefore, the description given above is also applicable.

[0060] Here, the tibial tray structure 21 has a T-shaped cross-section in a plane parallel to the distal surface D. The rod wall elements 22, 24, which form the bar of the T, are positioned essentially parallel to the anterior side, a rod wall element 25 forming the rod of the T is directed perpendicularly to the posterior side of the tibial tray 20.

[0061] Again, the three rod wall elements 22, 23, Petition 870250082988, dated 09 / 15 / 2025, page 24 / 82 17 / 38 of the tibial tray structure 21 have cross-sectional areas that converge in a strictly monotonous manner in the distal direction DD to axis A. The outer rims 22, 23, 24 have inclinations (measured against the distal plane) that are always greater than 0°, that is, the outer rims have no plateaus. But the outer rims 26 have three inflection points 27 at which there is a change in curvature.

[0062] Any change of a tangent angle over a height distance of 10% of the tibial tray structure meaning that there are no sharp curves in the outer rim 26. Changes in slope are smaller in the first third of the height of the tibial tray structure 21 measured from the distal surface. A further definition of the outer rim 26 is described in connection with Figure 19.

[0063] Figure 5 shows the embodiment of Figure 4 in a rear view. Here, a sectional plane C parallel to the distal surface D is shown. The sectional plane C separates the lower third of the tibial tray structure 21 from the upper two-thirds. For good mechanical load distribution, at least 50% of the volume of the rod wall elements 22, 23, 24 is between their sectional plane C and the distal surface D, that is, in the third closest to the distal surface D. This is also the case for other embodiments shown in Figures 2 and 3.

[0064] Figure 6 shows the same embodiment as that shown in Figures 4 and 5, that is, a tibial tray structure 21 with a T-shaped structure. In this view the shape of the outer rim 26 and the rounded transitions from the distal surface to the tibial tray structure 21 can be clearly seen in the figure.

[0065] In figure 6A, some geometry of the tibial plate perimeter 20 is described. The anterior radius Rant is between 30 mm and 60 mm. The lateral radius Rlat is between 15 mm and 30 mm and the posterior radius Rpost is between 10 mm and 20 mm, in particular 16 mm.

[0066] Figure 7 basically shows the same modality as figures 4 to Petition 870250082988, dated 09 / 15 / 2025, page 25 / 82 18 / 38 in a side view, so the above description is applicable. In addition to the embodiments described, this embodiment comprises one or more anterior and / or posterior cement retention structures, here the recess structures 28 in the tibial tray structure 21. When implanting the tibial tray 20 into the tibial bone, the cement can enter the recess type for better fixation. The recess structure 28 is shaped as a groove essentially parallel to the distal surface in this embodiment. Other shapes are possible in principle. One aspect here is that the cement retention structure 28 must be oriented in a way that the bone cement is not easily removed when implanting the tibial tray 20.

[0067] In Figure 8, a variant of the embodiment shown in Figures 4 to 7 is represented, that is, a T-shaped structure as a tibial tray structure 21. The distal surface D comprises a recess 14. Furthermore, it is indicated that the transition point of the outer rim 26 of the tibial stem structure 21 on the distal surface D is located at least 5 m (D1) from the lateral faces and / or the posterior side of the distal surface D. The median plane of the stem wall elements 22, 23 are extended to the lateral faces and / or the posterior side of the distal surface D, defining the distances D1. This allows for good placement of the tibial tray structure 21 on the bone.

[0068] Next, the modalities of the tibial tray 20 and the tibial insertion 30 are described, in particular the characteristics of the proximal surface P of the tibial tray 20 and the corresponding distal surface D of the tibial insertion 30.

[0069] Figures 9, 9A show a perspective view on the proximal surface P of the tibial tray 20. In Figure 9A, the tibial tray is shown to reduce complexity without the reference numbers, but with the reference planes M, N which are used subsequently to define the locations of features on the tibial tray 20. Petition 870250082988, dated 09 / 15 / 2025, page 26 / 82 19 / 38

[0070] Referring to figure 9A, a medial plane M is perpendicular to the proximal planar surface P and intersects the proximal surface P midway between the most lateral points L1, L2 of the proximal surface P. A frontal plane N is perpendicular to the medial plane M.

[0071] In one modality of the tibial tray 20, the dimensions are grouped into different sizes. There are eight different sizes for the distance between points L1 and L2. This is used to allow for artificial knee joints 100 for patients of different sizes. The smallest distance between L1 and L is 60 mm. The other seven sizes have distances of 64 mm, 68 mm, 72 mm, 76 mm, 80 mm, 84 mm, and 88 mm (i.e., using a 4 mm increment). Other modalities may use different absolute sizes and / or different increments; the increments do not have to be identical.

[0072] On the proximal surface extension P in the direction perpendicular to the distance between L1 and L2, the corresponding sizes are 38.7 mm, 41.3 mm, 43.9 mm, 46.5 mm, 49.0 mm, 51.6 mm, 54.2 mm, and 56.8 mm. Other modalities may use different absolute sizes and / or different increments; again, the increments do not have to be identical.

[0073] The proximal surface P of the tibial tray 20 is structured so that the corresponding tibial insert 30 (see, for example, Figure 1, 13) can be securely fixed to the tibial tray (see Figures 12A, 12B). The planar proximal surface P itself is polished, with an average roughness of Ra = 1 μm, in particular Ra = 0.1 μm and a uniformity of 0.1. In other embodiments, the average roughness is less than 5 μm, in particular less than 2 μm.

[0074] Different aspects of the structures are described below. 1, 2, 3 on the proximal planar surface P. The structures provide a symmetrical planar plateau with island-type fixation elements 1, 2, 3 for tibial insertion connection 30 using a press fit or en Petition 870250082988, dated 09 / 15 / 2025, page 27 / 82 20 / 38 interference box (see figure 11).

[0075] In the modality shown in figure 9, the proximal surface P comprises two central fixation elements 1. As will be described below, those two central fixation elements allow a secure connection with the tibial insertion (see figure 10B) as an additional part of the artificial knee joint 100.

[0076] In the embodiment shown, the two central fixation elements 1 are linear protrusions, projecting away from the proximal surface P in the proximal direction, so that they can match corresponding notches (or grooves) 34 on the tibial insertion 30 (see figure 10B). In other embodiments, the central fixation elements 1 could have a cylindrical shape. Other shapes and different positions of the central fixation elements 1 will be shown below.

[0077] The two central fixation elements 1 are positioned symmetrically and parallel to the medial plane M.

[0078] In an embodiment shown in figure 9B, the two central wiring elements 1 are still symmetrical to the medial plane M, but not quite parallel as they are inclined by less than 5° with respect to the median plane M so that the two linear fastening elements show convergence in the direction of the anterior side.

[0079] In other embodiments, it is also possible that the two central fixation elements 1 are asymmetrical to the median plane M, but parallel to each other.

[0080] As shown in Figure 14, in a different embodiment, more than two central fastening elements 1 can be used. Otherwise, the embodiment in Figure 14 is comparable to that described in connection with Figure 9.

[0081] In the modality shown in Figure 9, the two central fixation elements 1 are positioned with respect to the frontal plane N perpendicular to the medial plane M. in this modality, but not necessarily Petition 870250082988, dated 09 / 15 / 2025, page 28 / 82 21 / 38 precisely, the frontal plane N that passes through the most lateral points L1 L2 of the nearby surface P.

[0082] The two central fastening elements 1 are in the shape of a parallelepiped, the front and rear ends of the central fastening elements 1 are rounded.

[0083] The two central fixation elements 1 have a height H extending in the embodiment shown 3.8 mm from the proximal surface P of the tibial tray 20. In other artificial knee joints 100, the height H can be up to 6 mm. In the embodiment shown, the height H of the central fixation elements 1 is constant. In other embodiments, the height H may vary with respect to the proximal surface P. In other embodiments, the height H of at least the two central fixation elements 1 on the proximal surface varies by a maximum of 10% of the minimum height.

[0084] In the embodiment shown in Figure 9, the distance between the two central fastening elements 1 is 10.5 mm as measured between the inner walls and 15.5 mm as measured between the outer walls. Since the two central fastening elements 1 are parallel to each other, the width of each of the central fastening elements is 2.5 mm. The distance between the central fastening elements is chosen here to be as large as possible to provide a large torque and prevent shearing of the polyethylene material of the tibial insert 30. If the distance between the two central fastening elements 1 is always the same, tibial inserts 30 of different sizes can be used in the assembly of the artificial knee joint 100.

[0085] The orientation of the central fixation element 1 on the proximal surface P allows for linear guidance of the tibial insertion 30 during assembly (see figures 12A, 2B), so that the central wiring elements 1 could also be referred to as central guide rails. Furthermore, the central fixation elements 1 allow for an increase Petition 870250082988, dated 09 / 15 / 2025, page 29 / 82 22 / 38 stability against shear forces in the artificial knee joint.

[0086] The proximal surface P also comprises an anterior fixation element 2 that is located on the anterior rim of the proximal surface P. The posterior side of the anterior fixation element 2 comprises a posterior wall 4 that is positioned perpendicular to the medial plane M of the proximal surface P. Therefore, the posterior wall 4 is also essentially perpendicular to the two central fixation elements 1. The anterior fixation element 2 in this embodiment has the same height H as the central fixation element 1. In other embodiments, the heights of the anterior fixation element 2 and the central fixation elements 1 may be different.

[0087] The anterior fixation element 2 comprises two cavities 5, each in the form of a channel (i.e., the channel being open at both ends) with an essentially rectangular cross-section. As will be shown in connection with figures 12A, 12B, those cavities are form-fitting elements 5 cooperating with corresponding form-fitting elements 31 in the tibial insertion 30. The form-fitting elements 5 in the anterior fixation element are positioned symmetrically with respect to the medial plane M.

[0088] In other embodiments, the previous fastening element 2 comprises only one or more than two form-fitting elements 5. The cross-section of the cavities of the form-fitting elements 5 does not have to be rectangular, as, for example, round or polygonal cross-sections may also be used.

[0089] In the embodiment of Figure 9, the anterior fastening element 2 is a continuous element in the anterior rim of the tibial tray 20. In other embodiments, the anterior fastening element 2 may be divided into more than one part, for example, two elements, each of them Petition 870250082988, dated 09 / 15 / 2025, page 30 / 82 23 / 38 comprising a form 5 fitting element.

[0090] The two form-fitting elements 5 in the front fastener 2 are positioned in a region where the mechanical load transfer is less than 50% of the maximum load transfer. This is due to the fact that the channel-type form-fitting elements 5 slightly weaken the structure of the front fastener 1.

[0091] An additional structure on the proximal surface P is a posterior fixation element 3, which is positioned on the posterior rim of the proximal surface P. The posterior fixation element 3 is positioned symmetrically with respect to the medial plane M and comprises a posterior wall 7 level with the posterior rim 8 of the tibial tray 20. The posterior wall 7 follows the curved shape of the posterior rim 8 of the tibial tray 20. The cross-section of the anterior fixation element 3 in a plane parallel to the proximal surface P is symmetrical to the medial plane M. The posterior fixation element 3 in this embodiment has the same height H as the central fixation element 1. In other embodiments, the heights of the posterior fixation element 3 and the central fixation elements 1 may be different.

[0092] The embodiment shown in Figure 9 also comprises an anterior wall 9 of the posterior fastening element 3 and a posterior wall 4 of the anterior fastening element 2. The respective rims of those walls 4, 9 on the proximal surfaces of the posterior element 3 and the anterior fastening element 2 are parallel to each other. If the walls 4, 9 had no cutouts (that is, the walls 4, 9 are not inclined), the walls 4, 9 would properly be parallel. Therefore, the two central fastening elements 1 are oriented perpendicular to the posterior wall 4 of the anterior fastening element 2 and to the anterior wall 9 of the anterior fastening element 3.

[0093] The rear fastening element 3 also comprises du Petition 870250082988, dated 09 / 15 / 2025, p. 31 / 82 24 / 38 the lateral walls 10 which are angled with respect to the anterior wall 9 of the posterior fixation element 3. The angle α between the two lateral walls 10 and the anterior wall 9 in a plane parallel to the proximal plane P is in the range of 0° and 22°, in particular in the range between 14° and 22°. Therefore, the two lateral walls 10 are oriented convergently in the anterior direction. The overall horizontal shape of the posterior fixation element 3 is roughly trapezoidal, with the long side of the trapezoid being curved.

[0094] The two lateral walls 10 of the posterior fastening element 3 are inclined inwards to form a recess by an angle between 1 and 45°, in particular 20 and 30° with respect to a plane that is perpendicular to the proximal plane P. Therefore, the upper surface of the posterior fastening element 3 is slightly larger than the cross-section of the base in the plane of the proximal surface.

[0095] In the embodiment described herein, and best seen in Figure 12B, the anterior wall 9 of the posterior fixation element 3 comprises a recess 6, the recess 6 forming an angle β between 1° and 45°, in particular 30° with a plane perpendicular to the proximal surface P. In other embodiments, the recess 6 may have – at least in part – a curved shape. In principle it is also possible that the posterior wall 4 of the anterior fixation element 2 comprises a recess 6.

[0096] In the modalities discussed so far, the height H of the fixation elements 1, 2, 3 above the proximal surface P was identical. This does not need to be the case in all modalities.

[0097] The corresponding tibial tray 20 and the tibial insertion 30 are shown side by side in Figure 10A, 10B. The embodiment of the tibial tray 20 in Figure 10A has already been described in Figure 9, so reference can be made to the respective description. The distal surface D of the tibial insertion 30 is shown in Figure 10B. The comparison of the two parts 20, 30 means that the tibial insertion 30 can be connected with the Petition 870250082988, dated 09 / 15 / 2025, page 32 / 82 25 / 38 tibial tray 20 so that the first fastening elements 1 fit into corresponding notches 34 in the tibial insert 30.

[0098] The tibial insertion 30 comprises a recess 32 (see figure 10B) on the distal surface D for the corresponding posterior fixation element 3 of the tibial tray 20. The recess 32 is open to the posterior side, so that it has only one anterior wall 35 and two lateral walls 36.

[0099] The side walls 36 of recess 32 are angled to match the angled walls 10 of the rear fastening element 3. At the corners where the front wall 35 and the two side walls 36 of recess 32 meet, stress relief notches 33 are located at the junction of the two walls 35, 36.

[00100] On the anterior side of the tibial tray insert 30, two shape-shaped elements 31 are positioned which can be inserted into the two cavities of the shape-shaped fitting elements 5 in the anterior fastening element 2 (see figure 9).

[00101] The notches 34 and the recess 32 of the tibial tray 30 also form some form-fitting connection with the corresponding structures, namely the central fastening element 1 and the rear fastening element 3 of the tibial tray 20. But the main function of the structures 32, 34 is an assistance during assembly which will be described below in connection with figures 12A, 12B.

[00102] The connection between the tibial tray 20 and the tibial insert 30 is primarily effected by a press-fit connection between the tibial insert 30 and at least two central fixation elements 1, at least one anterior fixation element 2 and at least one posterior fixation element 3, in particular having a press-fit in the range of 0 to 450 μm, more particularly in the range of 0 to 250 μm in the anterior-posterior direction. In Figure 11, the surfaces 37 for the press-fit on the posterior wall 4 of the an fixation element are shown. Petition 870250082988, dated 09 / 15 / 2025, page 33 / 82 26 / 38 interior 2, within the central fastening element 1 and the front wall 9 of the rear fastening element 9 are highlighted. It is possible that all press-fit connections are identically dimensioned, but this does not have to be the case for all embodiments. For example, the press-fit between the rear wall 4 of the front fastening element 2 and the front wall 9 of the rear fastening element 3 is in the range of 50 to 150 μm and / or the press-fit between the rear fastening elements 1 is in the range of 50 to 100 μm. The side surfaces of the recess 32 provide an interference fit.

[00103] In figures 12A and 12B, the assembly of modalities of a tibial insert 30 and a tibial tray is shown in different views.

[00104] Figure 12A shows a front perspective view with the tibial insert 30 partially connected with the tibial tray 20 below. Figure 12B shows essentially the same relative position of the tibial tray 20 and the tibial insert 30, but in a sectional view, with the anterior fastening element 2 on the right-hand side.

[00105] The tibial insert 30 is first connected with the posterior attachment element 3 (see figures 9, 10A, 10B) which is used as some kind of support point for the fitting. In the view of figure 12B, the cutout 6 in the anterior wall 9 is shown at an angle of approximately 15° which allows for secure positioning of the tibial insert 30. On the anterior side (see figure 12A), the two form fitting elements 31 are shown which fit into the cavities of the form fitting element 5 (not seen in figure 12A).

[00106] In Figure 13A, a first embodiment of a tibial insertion 30 is shown in a frontal view. In this embodiment, the shape of the distal surface D does not fit with the footprint, that is, the outer rim of the tibial insertion 30 is essentially a slightly inclined wall. The inclination can be between 0 and 10°. In the case of inclination Petition 870250082988, dated 09 / 15 / 2025, page 34 / 82 27 / 38 0° the wall is straight.

[00107] In figure 13B, a second embodiment of a tibial insertion 30 is also shown in a frontal view. Here, the distal surface shape D is fitted into the footprint, i.e. the outer wall is slightly inclined outwards.

[00108] Although the above-described artificial knee joint 100 with a metal-free tibial tray 20, in particular ceramic, is a preferred embodiment, it is possible that the tibial tray 20 or the complete knee joint 100 may be made of metal or polymeric material or comprising these materials.

[00109] Figures 15A, 15B and 15C show the distal surface D of the tibial plate 20. Figure 15A shows an anterior view, Figure 15B shows a posterior view, Figure 15C shows a top view of the distal surface D.

[00110] The tibial tray structure 21 is essentially an X-shaped structure, wherein the angle y1 between the first and second rod wall elements 22, 23 differs from the angle y2 between the third and fourth rod wall elements 24, 25. The angle y1 between the first and second rod wall elements 22, 23 facing the posterior side is smaller than the angle y2 between the third and fourth rod wall elements 24, 25. In the embodiment shown, the angle y1 between the first and second rod wall elements 22, 23 is less than 90°, i.e., 80° (see figure 15B); the angle y2 between the third and fourth rod wall elements 24, 25 is greater than 90°, i.e., 120°. In one embodiment, the angles y1 and y2 are 110° and 70°, respectively.

[00111] In other embodiments, such as those shown in Figure 9, the central wiring elements 1 had a shape with two axes of symmetry, one along the long axis and the other on the axis perpendicular to this axis. Figures 16A and 16B show an embodiment of a Petition 870250082988, dated 09 / 15 / 2025, page 35 / 82 28 / 38 tibial plate 20 which deviates from this pattern.

[00112] Figures 16A, 16B show an embodiment in which the central fastening elements 1 have a wider lateral cross-section in the anterior direction than in the posterior direction. Therefore, the long lateral walls of each of the central fastening elements 1 are converging towards the anterior side. The inner lateral walls of the central fastening elements 1 are not parallel and are divergent towards the posterior side of the tibial tray 3, while the outer lateral walls are essentially parallel.

[00113] Figure 17 shows a variant embodiment of the tibial tray 20, in which the central fixing elements 1 are shaped differently. Here, the outer side walls of the central fixing elements 1 are parallel to each other and there are two axes of symmetry, as in the embodiment shown in Figure 9. In the embodiment of Figure 17, the inner side walls are not linear over their entire lengths. In the direction of the anterior and posterior sides, the side walls are converging, towards the middle they are diverging.

[00114] The front fastening element 2 of the modalities shown in figures 16A, 16B and 17 is formatted like the modality shown in figure 9. But the rear fastening elements 3 of the modalities shown in figures 16A, 16B and 17 are formatted differently.

[00115] The lateral walls of posterior element 3 are inclined at an angle between 0 and 45°, in particular between 0 and 30° with respect to a plane that is perpendicular to the proximal plane P. In addition, or alternatively, the lateral walls and the anterior wall of at least one posterior element 3 comprise a cutout.

[00116] In figures 18A, 18B, the cross-sections in a frontal plane N (see, for example, figure 9A) are shown for one embodiment. Figure 18A shows a view in the anterior direction, that is, the Petition 870250082988, dated 09 / 15 / 2025, page 36 / 82 29 / 38 front fastener 2 can be seen behind the center fastener 1, which is shown in cross-section. Figure 18B shows a view to the same front plane N, but in the rear direction.

[00117] Cross-sections of the central fixation elements 1 show that they comprise central fixation element recesses 12 (cutouts) at the transition to the proximal surface P and along the inner lateral walls. The central fixation element recesses 12 have grooves with a constant radius. In a different embodiment not shown here, the central fixation element recesses 12 may also be located on the outer lateral walls of the central fixation elements 1 or only on the outer lateral walls.

[00118] Figures 18A, 18B also show cement retaining structures 28 which will be described in more detail in connection with figures 20A and 20B.

[00119] Figure 19 shows a schematic representation of a view in the anterior direction with the tibial tray structure 21 (here a T-shaped structure) pointing upwards in the distal direction. This representation is not shown as a particular embodiment of a tibial tray 20, but is intended to indicate how the shape of the outer rim 26 of the lateral walls (e.g., in Figures 4 and 5) can be generated. In this exemplary embodiment, the outer rim 26 follows a strictly monotonous curve with inflection points. A possible generation of this curve is described below using a number of line segments M1, M2, M3, M4, M5 that are connecting the distal plane D with the distal tip of the tibial tray rod structure 21.

[00120] The first line segment M1 is connecting the distal plane D with a first point P1 in the distal plane D. The first point P is literally positioned around 68% of the distance from the plane. Petition 870250082988, dated 09 / 15 / 2025, page 37 / 82 30 / 38 medial M (see figure 9A) and the outermost point of the lateral rim. The inclination of the first line segment M1 is approximately 20° as measured from the distal plane D. In alternative modalities, the first point P1 is laterally positioned within a range of 55 to 75% of the distance from the medial plane M to the outermost point of the lateral rim. In an alternative modality, the inclination of the first line segment M1 may also be in the range between 15° and 30° as measured from the distal plane D. The modalities can be combined.

[00121] The second line segment M2 connects the first point P1 with a second point P2 above the distal plane D. The second point P2 is vertically positioned approximately 15% of the distance from the distal plane D to the plane parallel to the most distal point of the tibial tray rod structure 21. The inclination of the second line segment M2 is approximately 40% when measured from the distal plane D. In alternative modalities, the second point P2 is vertically positioned within a range of 10 to 20% of the distance from the distal plane D to the plane parallel to the most distal point of the tibial tray rod structure 21. In an alternative modality, the inclination of the second line segment M2 may also be in the range between 30° and 50° when measured from the distal plane D. The modalities can be combined.

[00122] The third line segment M3 connects the second point P2 with a third point P3 above the distal plane D. The third point P3 is vertically positioned approximately 33% of the distance from the distal point D to the plane parallel to the most distal point of the tibial tray rod structure 21. The inclination of the third line segment M3 is approximately 60° when measured from the distal plane D. In alternative embodiments, the third point P3 is vertically positioned within a range of 25 to 40% of the distance from the distal plane D to the plane parallel to the most distal point of the structure. Petition 870250082988, dated 09 / 15 / 2025, page 38 / 82 31 / 38 tibial tray rod 21. In an alternative modality, the inclination of the third segment of line M3 may also be in the range between 45° and 0° when measured from the distal plane D. The modality may be combined.

[00123] The fourth line segment M4 connects the third point P3 with a fourth point P4 above the distal plane D. The fourth point P4 is vertically positioned at approximately 50% of the distance from the distal plane D to the plane parallel to the most distal point of the tibial tray rod structure 21. The inclination of the fourth line segment M4 is approximately 50° as measured from the distal plane D. In alternative modalities, the fourth point P4 is vertically positioned within a range of 40 to 60% of the distance from the distal plane D to the plane parallel to the most distal point of the tibial tray rod structure 21. In an alternative modality, the inclination of the fourth line segment M4 may also be in the range between 40° and 60° as measured from the distal plane D. The modalities may be combined.

[00124] The fifth line segment M5 is connecting the fourth point P4 with a point on the central structure of the tibial tray rod 21. The inclination of the fifth line segment M5 is approximately 75% as measured from the distal plane D. In other modalities, the inclination of the fifth line segment M5 is in the range of 50° to 80° as measured from the distal plane D. The modalities can be combined.

[00125] Line segments M1, M2, M3, M4, M5 have varying slopes, such that approximately in the middle, the slope of the fourth line segment M4 is steeper than that of the third line segment M3.

[00126] The points defining the line segments can be fitted with a smooth curve, such as a polynomial or a spline curve, to generate the smooth contour of the outer rim 26 of one of the structures. Petition 870250082988, dated 09 / 15 / 2025, page 39 / 82 32 / 38 of tibial tray rod 21, that is, the two lateral rod elements in the T-structure are shown in figure 19.

[00127] Figures 20A and 20B show an embodiment of a tibial tray 20 in perspective views. Essentially, the embodiment has the characteristics described above, but the tibial stem structure 21 – here a T-shaped structure – comprises relatively close to the distal surface cement retention structure D 23. The anterior side – best seen in Figure 20A – comprises a groove as a cement retention structure 28 through two wall elements. The posterior side – best seen in Figure 20B – comprises two grooves as a cement retention structure 28 each extending over two wall elements, i.e., traversing the rounded corner between the wall elements.

[00128] The cement retaining structures 28 are designed here as rounded grooves that are easy to manufacture. In other embodiments, they may also comprise or consist of other shapes, for example, grooves with sharp corners or holes with round or polygonal cross-sections.

[00129] Figures 21A, 21B show an embodiment of the tibial tray 20 which is a variant of the embodiments described above, such as those shown in Figures 20A, 20B, but here without the cement retention structure 23. The tibial tray rod structure 21 comprises a base rod structure shaped like a vertical cylinder 29 extending around the axis A of the tibial tray rod structure 21. The diameter of this base rod structure 29 is between 5 and 8 mm, in particular depending on the size of the tibial tray 20. The diameter can vary in distinct steps, such as 5 mm, 6 mm, 7 mm, and 8 mm. The cross-section of the base rod structure 29 does not have to be circular. Other shapes, such as elliptical or polygonal, are also possible. Petition 870250082988, dated 09 / 15 / 2025, page 40 / 82 33 / 38

[00130] As discussed above, three wall elements 22, 23, 24 (Y-structure, T-structure) or four wall elements 22, 23, 24, 25 (X-structure) extend radially away from the base rod structure 29. The angles between wall elements 22, 23, 24, 25, for example, are described in connection with figures 15A, 15B, 15C. The angular spaces between wall elements 22, 23, 24, 25 are smoothly filled with curved surfaces 13, for example, connecting adjacent wall elements 22, 23, 24, 25. Figure 21B shows the rear view of a tibial tray 20 (T-structure). The radius of the curved surface 13 near the base rod structure 29 is between 1 and 9 mm, in particular between 3 and 5 mm. Similar curved surfaces with the same radii would be used between wall elements in X-structures or Y-structures.

[00131] Figure 21A shows the front view of the T-structure shown in Figure 21B. Here, the cylindrical base rod structure 29 extends forward beyond the two front wall elements 22, 23. The curved surface 23 on the front side here is between 10 mm and 30 mm, in particular 20 mm.

[00132] Those curved surfaces 13 prevent sharp edges, inter alia, which improves the ability to insert the tibial tray.

[00133] Figure 22 shows the proximal surface P of a tibial tray 20 comprising a variation in the design of the anterior fixation element 2 over the embodiments described above. The central fixation elements 1 and the posterior fixation element 3 have been described in one manner or another, for example, in Figure 9 or 16A, so reference may be made to the description above.

[00134] The anterior fastening element 2 comprises two shape-fitting elements 5 to receive a corresponding part of the tibial insert 30 (not shown here, see figures 12A, 12B, for example). Petition 870250082988, dated 09 / 15 / 2025, page 41 / 82 34 / 38 plo, for the tibial tray fitting process). The form 5 fitting elements are essentially holes with a rectangular cross-section.

[00135] As the tibial insert 30 is inserted from the top using its back and the posterior fixation device 3 as a support point, the form fitting elements 31 for anterior fixation have a shape that corresponds with the form fitting elements 5 (e.g., the rectangular holes).

[00136] To facilitate the fitting of the tibial insert 30 (not shown here), guide surfaces 11 are provided on the proximal surface of the device and anterior fixation 5. The guide surfaces 11 here are planes inclined by 5° to 45° against the horizontal plane, in particular inclined by 30°. In other embodiments, not shown here, the guide surface is curved or has a flat part.

[00137] The shape-fitting elements 31 of the tibial insert 30 project anteriorly. When the tibial insert 30 is to be fitted, the shape-fitting elements 31 first seat on the upper parts of the guide surfaces 11. When pressure in the distal direction is applied to the tibial insert 30, the shape-fitting elements 31 are guided downwards along the guide surfaces 11 and eventually engage in the holes, forming the shape-fitting elements of the anterior fixation element 5 for a secure fit. The guide surfaces 11 prevent compromise of the shape-fitting elements 5 during insertion and make secure fitting easier.

[00138] The lateral width of the guide surface is the same or about the same as the lateral width of the form 5 fitting elements in the previous fastening element 2.

[00139] In figure 23 a detail of the rear fastening element 3 is shown in a top view, that is, in the direction of the pro surface. Petition 870250082988, dated 09 / 15 / 2025, page 42 / 82 35 / 38 maximum P.

[00140] The cross-section of the posterior fixation element 3 comprises two lateral walls 10 that are inclined towards the medial plane M. Each of the lateral walls 10 is inclined by approximately 20° against the medial plane M. In the embodiment shown, there is a deliberate angular misalignment between the lateral walls 10 of the posterior fixation element 3 and the corresponding lateral walls of the tibial insertion 30 (not shown here).

[00141] If, for example, the side walls of the tibial insert 30, which are intended to come into contact or form-fit with the side walls 20 of the posterior fastening element 3, have a slightly different inclination from the side walls 10, an angular misalignment is created causing a closer contact or force fit in some parts of the side walls 10 and a looser fit in others.

[00142] In the embodiment shown in Figure 23, the angle of the lateral walls of the posterior fastening element 3 is wider (for example, by about 1°) than the corresponding angle in the recess in the tibial insertion 30. This causes a form fit, that is, a tighter fit in the posterior area. The pressure fit region 38 in this area is indicated in Figure 23. This angular misalignment not only allows for easier assembly but also reduces micromovements in the posterior regions.

[00143] In other embodiments, the pressure fitting region 38 is created by widening the rear part of the rear fastening element 3. REFERENCE SIGNS - central fastening element - previous fastening element - rear fastening element Petition 870250082988, dated 09 / 15 / 2025, page 43 / 82 36 / 38 - rear wall of a previous wiring element - fitting element in the shape of the previous fastening element - cutout in the wall for the rear fastening element - rear wall of the rear fastener - posterior rim of the tibial tray - anterior wall of the posterior fastening element - side wall of the rear fastener - guide surface for a tibial insertion into the anterior fixation element - central fastening element recess - curved surface between rod wall elements - recess on the distal surface tibial plate - tibial tray rod structure - first wall element of tibial tray rod structure - second tibial tray rod frame rod wall element - third element of the tibial tray rod structure wall - fourth element of tibial tray rod structure wall - outer rim of the rod wall element - inflection point on the outer rim of the rod wall element - Cement retention structure, recess structure in the stem wall element for bone cement base stem structure - base rod structure tibial insertion - form fitting element for previous wiring element Petition 870250082988, dated 09 / 15 / 2025, page 44 / 82 37 / 38 - recess for rear fastening element - relief notch - notch / groove in the tibial insertion for central fixation element - recessed front wall - side wall of the recess - press-fit surface - pressure fitting region due to angular misalignment - femoral part 100 - artificial knee joint A - axis of the tibial tray rod structure C - cross-sectional plane D - distal surface of tibial tray DD - distal direction D1 - distance H - height of a fastening element L - height of the tibial tray structure measured from the distal surface L1 - lateral point of the proximal surface L2 - lateral point of the proximal surface M - medial plane of the proximal surface of the tibial plateau M1 - first line segment defining the outer rim of the rod element. M2 - second tibial tray rod frame rod wall element M3 - third element of the tibial tray rod structure wall M4 - fourth tibial tray rod frame rod wall element M5 - fifth rod wall element of rod structure Petition 870250082988, dated 09 / 15 / 2025, page 45 / 82 38 / 38 tibial tray N - frontal plane perpendicular to the medial plane P - proximal surface of the tibial tray P1 - first point between the line segments defining the outer rim of the rod element. P2 - second point between the line segments defining the outer rim of the rod element. P3 - third point between the line segments defining the outer rim of the rod element. P4 - fourth point between the line segments defining the outer rim of the rod element. R - distal surface rim R1 - radius R2 - radius Rant - anterior ray Rlat - lateral radius Rpost - posterior ray S - smooth surface T - thickness of the rod wall element α - angle between the lateral walls and the anterior wall of the anterior fixation element in a plane parallel to the proximal surface β - cut angle y1 - angle between the first and second wall structures of a tibial tray structure y2 - angle between the third and fourth wall structures of a tibial tray structure

Claims

1. Tibial tray (20) with a distal surface (D), characterized in that the tibial tray rod structure (21) extends away from the distal surface (D) in the distal direction (DD), wherein: the tibial tray structure (21) comprises at least three rod wall elements (22, 23, 24, 25) which are arranged with respect to each other such that the cross-sections of the at least three rod wall elements (22, 23, 24, 25) in a plane perpendicular to the distal direction (DD) are T-shaped, Y-shaped or X-shaped; and the area of ​​the cross-sections decreases in a strictly uniform manner from the distal surface (D) in the distal direction (DD).

2. Tibial tray (20), according to claim 1, characterized in that the outer rims (26) of at least three rod wall elements (22, 23, 24, 25) converge in a strictly uniform manner in the distal direction (DD) and to an axis (A) of the tibial tray structure (21).

3. Tibial tray (20), according to claim 1 or 2, characterized in that the outer rims (26) of at least three rod wall elements (22, 23, 24, 25) have at least one inflection point (27), in particular three inflection points (27).

4. Tibial tray (20), according to any of the preceding claims, characterized in that any change of a tangent angle (y) in an outer rim (26) of the at least three rod wall elements (22, 23, 24, 25) is less than 30° over a 10% change in the distal direction, in particular any tangent angle (y) of the outer rim (26) of the at least three rod wall elements (22, 23, 24, 25) within one third of the height (L) of the tibial tray structure (21) measured from the distal surface (D).

5. Tibial tray (20), according to any of the preceding claims, characterized in that at least 50% of the volume of the tibial tray structure (21) is located within one third of the height (L) of the tibial tray structure (21) measured from the distal surface (D).

6. Tibial tray (20), according to any of the preceding claims, characterized in that at least one of the rod wall elements (22, 23, 24, 25) has a wall thickness (T) between 1 and 6 mm, in particular between 2 and 5 mm, in particular for ceramic materials between 1 and 5 mm, measured at the furthest point from the axis (A) and on the distal surface (D).

7. Tibial tray (20), according to any of the preceding claims, characterized in that the radius (y) at the transition from the outer rim (26) of at least one of the at least three rod wall elements (22, 23, 24, 25) to the side walls of at least one of the at least three rod wall elements is in the range of 0.5 to 4 mm.

8. Tibial tray (20), according to any of the preceding claims, characterized in that at least one of the at least three rod wall elements (22, 23, 24, 25) comprises at least one cement retention structure, in particular at least one recess structure (28) for retaining bone cement, in particular on the anterior and / or posterior side.

9. Tibial tray (20), according to any of the preceding claims, characterized in that the transition point of the outer rim (26) to the tibial stem structure (21) on the distal surface (D) is located at least 5 mm from the lateral faces and / or the posterior side of the distal surface (D).

10. Tibial tray (20), according to any of the preceding claims, characterized in that the tibial tray structure (21) comprises a surface (S) extending between at least two of the outer rims (26) of the at least three rod wall elements (21) or between two side walls of the at least three rod wall elements (21).

11. Tibial tray (20), according to any of the preceding claims, characterized in that the radius (R1) at the transition from the distal surface (D) to at least one of the at least three rod wall elements (22, 23, 24, 25) and / or the smooth surface (S) is in the range of 1 to 4 mm.

12. Tibial tray (20), according to any of the preceding claims, characterized in that the axis (A) of the tibial tray rod structure (21) is located on the distal surface (D) at one third of the distance between the anterior rim to the posterior rim, measured from the anterior rim.

13. Tibial tray (20), according to any of the preceding claims, characterized in that the angle (y1) between the rod elements (22, 23) is between 30° and 120° on the posterior side and the angle (y2) between the rod wall elements (24, 25) is between 90° and 180° on the anterior side.

14. Tibial tray (20), according to any of the preceding claims, characterized in that the tibial tray rod structure (21) comprises at least one cement retention structure (28), in particular a hole, a groove and / or a recess without any cutout.

15. Tibial tray (20), according to claim 14, characterized in that at least one cement retention structure (20) is located within the vertical two-thirds of the tibial tray rod structure (21) measured from the distal surface (D) in the distal direction (DD), in particular within the first third. Petition 870250082988, dated 09 / 15 / 2025, page 49 / 82 4 / 6 16. Tibial tray (20), according to any of the preceding claims, characterized in that at least one anterior fixation element (2), in particular exactly one anterior fixation element (2), is positioned on the anterior side of the proximal surface (P), the posterior side of the at least one anterior fixation element (2) comprising a wall (4) which in a plane parallel to the proximal surface (P) is perpendicular to the medial plane (M) of the proximal surface (P).

17. Tibial tray (20), according to claim 16, characterized in that the at least one anterior fixation element (2) comprises at least one form fitting element (5), in particular, at least one cavity in the posterior wall (4) of the at least one anterior fixation element (2) and / or at least one channel through the at least one anterior fixation element (2), for a corresponding form fitting element (31) of the tibial insertion (30), the at least one form fitting element (5) of the at least one anterior fixation element (2) being in particular positioned in a region where the load transfer is less than 70%, in particular 50% of the maximum load transfer.

18. Tibial tray (20), according to claim 17, characterized in that at least one anterior fixation element (2) comprises at least one guide surface (11) for a tibial insertion (30), in particular the guide surface (11) having a curved and / or a flat part, in a proximal direction of at least one form fitting element (5).

19. Tibial tray (20), according to claim 18, characterized in that at least one guide surface (11) comprises a flat part or is a plane that is inclined with respect to the horizontal plane by an angle in the range of 5 to 45°, in particular 30°. Petition 870250082988, dated 15 / 09 / 2025, p. 50 / 82 5 / 6 20. Tibial tray (20), according to any of the preceding claims, characterized in that a proximal surface (P) comprising at least two, in particular, exactly two central fixation elements (1) to allow a connection with a tibial insertion (30) as an additional part of an artificial knee joint, wherein the at least two central fixation elements (1) are protrusions of the proximal surface (P) in the proximal direction and the at least two central fixation elements (1) are positioned symmetrically and / or parallel to the medial plane (M) of the proximal surface (P), the medial plane (M) being perpendicular to the proximal surface (P) and intersecting the proximal surface (P) midway between the two most lateral points (L1, L2) of the proximal surface (P).

21. Tibial tray (20), according to any of the preceding claims, characterized in that the at least two central fastening elements (1) comprise a central fastening element recess (12).

22. Tibial tray (20), according to any of the preceding claims, characterized in that at least one posterior fixation element (3), in particular exactly one, is positioned symmetrically to the medial plane (M) of the proximal surface (P) comprising a posterior wall (7) level with the posterior rim (8) of the tibial tray (20) and / or comprising an anterior wall (9) that is essentially positioned parallel to the posterior wall (4) of at least one anterior fixation element (2).

23. Tibial tray (20), according to claim 22, characterized in that the lateral walls (10) and / or the anterior wall (9) of at least one posterior element (3) is inclined by an angle between 0 and 45°, in particular between 0 and 30°, more particularly by an angle of 10°, with respect to a plane that is perpendicular to the proximal plane (P) and / or the lateral walls (10) and the anterior wall (9) of at least one posterior element (3) comprises a cutout.

24. Tibial tray (20), according to any of the preceding claims, characterized in that at least two central fixation elements (1) are oriented symmetrically and / or parallel to the medial plane (M) or the at least two fixation elements (1) are oriented asymmetrically with respect to the medial plane (M).

25. Tibial tray (20), according to any of the preceding claims, characterized in that it is made wholly or partly of ceramic, a polymeric material or a metal.

26. Artificial knee joint (100), characterized in that it comprises a tibial tray (20), according to any one of claims 1 to 23 and a tibial insert (30).

27. Artificial knee joint (100), according to claim 25, characterized in that at least one pressure fitting region (38) between the posterior fixation element (3) and the tibial insertion (20), in particular created by an angular misalignment between the two walls.

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