Tibial components and knee prosthesis systems

Abstract

It is proposed to provide a tibial component for a knee joint prosthesis, comprising a tibial plate having an upper surface and a lower surface, and a fixation projection protruding from the lower surface so as to be insertable into the medullary cavity of the tibia to fix the tibial component to the tibia, the fixation projection being attached to the tibial plate so as to be pivotable and / or rotatable about a longitudinal axis of the fixation projection to provide a tibial component that allows for improved alignment on the tibia.Furthermore, an improved knee joint prosthesis system is proposed.

Description

[Technical field]

[0001] The present invention relates to a tibial component for a knee joint prosthesis, the tibial component comprising a tibial plate having an upper surface and a lower surface, and a fixation protrusion protruding from the lower surface so as to be insertable into the medullary cavity of the tibia to fix the tibial component to the tibia, the fixation protrusion being attached to the tibial plate so as to be rotatable and / or swivelable about a longitudinal axis of the fixation protrusion, the tibial component comprising a fixation device for fixing the fixation protrusion in an implantation position, the fixation device being movable from an alignment position in which the fixation protrusion and the tibial plate are movable and alignable relative to each other, to the implantation position in which the fixation protrusion and the tibial plate are held relative to each other so as not to move relative to each other.

[0002] The present invention also relates to a knee joint prosthesis system comprising at least one femoral component for fixation to a distal end of the femur and at least one tibial component for fixation to a proximal end of the tibia, the at least one femoral component and the at least one tibial component being configured to correspond to each other to form a knee joint prosthesis. [Background technology]

[0003] Knee prosthesis systems of the kind described at the beginning are used to replace a patient's damaged knee joint by implanting a knee prosthesis that is suitable for the patient. Despite the wide range of prostheses available, there is still a significant number of patients who are dissatisfied with the results after the implantation of a knee prosthesis. One particular problem is the optimal orientation, also called alignment.

[0004] A new approach to improve patient satisfaction is the so-called kinematic alignment method. The kinematic alignment method is based on the positioning of the knee prosthesis taking into account the natural individual kinematic axes of the anterior knee joint. This returns the natural joint line and the position of the leg axis to their original alignment. This also theoretically maintains the natural stable capsular ligament tension without loosening the ligaments by so-called "release". In contrast to this new approach, in the classical alignment of the knee prosthesis, the implant components, especially the tibial and femoral components, are aligned perpendicular to their functional axes.

[0005] A tibial component and knee joint prosthesis system of the type described at the outset is known from DE 202007004508 A1.

[0006] It is therefore an object of the present invention to provide a tibial component and knee joint prosthesis system of the kind described in the introduction, which can be particularly simplified in its handling. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] German Utility Model No. 202007004508 Summary of the Invention

[0008] According to the invention, this object is achieved in a tibial component of the type described at the beginning, in that the fixation device comprises a fixation element and the second joint element in the implantation position is clamped and held between the fixation element and the first joint element.

[0009] The solution proposed by the invention makes it possible in particular to provide a tibial component that allows a desired alignment of the fixation projection relative to the tibial plate. The fixation projection can in particular be attached to the tibial plate so as to be infinitely rotatable and / or rotatable. Alternatively, it is also possible to predetermine in particular several predefined pivot and rotation positions of the fixation projection relative to the tibial plate, i.e. detent pivots or rotations. In this case, several different alignments of the fixation projection relative to the tibial plate are possible, but not in an infinite manner. As a result of the special attachment of the fixation projection to the tibial plate proposed by the invention, it is possible in particular to always optimally align the fixation projection so that it can be inserted anatomically correct in the medullary cavity of the patient's tibia. This makes it possible in particular to prevent collisions of the fixation projection with the bone surfaces of the tibia that delimit the medullary cavity. In particular, the fixation projection of the tibial component can therefore be aligned in any way, both in the anterior-posterior direction and in the medial-lateral direction. Thus, stress peaks caused by pressure or edge loading of the fixation projection in the medullary cavity of the inner cortex of the tibia can be minimized. Due to the above-mentioned ability to optimally align the fixation projection of the tibial component, in particular the kinematic alignment of the knee joint prosthesis can be achieved for every patient, i.e. for each patient. In particular, this allows to maintain a natural and stable capsular ligament tension without the need to reduce the ligament tension by partially cutting the ligaments of the patient's knee. So-called "release" is therefore not necessary. According to the invention, the tibial component comprises a fixation device for fixing the fixation projection in the implantation position, which is movable from an alignment position in which the fixation projection and the tibial plate are movable and alignable relative to each other, to the implantation position in which the fixation projection and the tibial plate are held relative to each other so that they do not move relative to each other. Thus, the fixation device allows to fix the fixation projection in a desired alignment relative to the tibial component.In the alignment position, the tibial plate and the fixation projection are attached or held relative to each other, but are movable relative to each other so that they can be aligned (positioned) relative to each other in a desired manner. By moving the fixation device from the alignment position to the implantation position, the mobility of the fixation projection and the tibial plate relative to each other is released, so that the tibial component can be permanently fixed to the tibia in a predefined manner, i.e. without the fixation projection and the tibial plate moving relative to each other. In the following, the term "fixation position" is used synonymously with the term "implantation position". The fixation device preferably comprises a fixation element, the second joint element in the implantation position being clamped and held between the fixation element and the first joint element. The fixation device thereby forms in particular a clamping device for the second joint element, allowing for clamping and fixing the second joint element (e.g. a spherical articular projection) in a hollow spherical articular receptacle. Such a clamping device allows in particular an easy handling of the tibial component during implantation. DE 202007004508 A1 discloses a solution for immobilizing a fixation lug on a tibial plate in a fixed position using tension forces.

[0010] For this purpose, a tension anchor is used which is rotatably attached to the shaft adapter. In contrast, in the further development proposed in the present invention, the fixing lug and the tibial plate are held immovably relative to each other in the fixed position only by a pressing force. In the fixed position, the fixing element presses the second articular element against the first articular element in a clamping manner. This makes handling easier, since, unlike in the case of the tibial component described in DE 202007004508 A1, the fixing lug does not have to be rotated when transferring the tibial component from the alignment position to the fixed position. This makes it possible to transfer the tibial component from the alignment position to the fixed position without first holding the fixing lug and the shaft which may be coupled to the fixing lug at the distal side, only if the fixing lug has already been inserted into the cavity of the tibia. This simplifies the alignment of the fixing lug and reduces the time required for implantation.

[0011] For stable fixation of the tibial component, the fixation projection is preferably arranged or formed in the area of ​​the symmetrical plane of the tibial plate.

[0012] Preferably, the fixation projection is arranged or formed in a central or central area of ​​the lower surface of the tibial plate, so that, in particular, the fixation projection can be firmly inserted and fixed in the central medullary cavity of the tibia.

[0013] The fixing projection is preferably configured rotationally symmetrically or substantially rotationally symmetrically with respect to the longitudinal axis of the fixing projection, for example the fixing projection may be configured in the form of a cylindrical stump or in the form of a truncated cone.

[0014] Advantageously, the fixing projection is attached to the tibial plate in an articulated manner. In particular, the fixing projection may be attached to the tibial plate in a hinged or ball-jointed manner. Depending on the type of attachment, an optimal adjustability of the fixing projection to the tibial plate can be achieved. In particular, attaching one end of the fixing projection in a ball-jointed manner allows the free end of the fixing projection to be freely aligned within a predefined angular range relative to the surface normal of the lower surface of the tibial plate, which ranges over a 360° rotational range relative to the surface normal.

[0015] According to a preferred embodiment, the tibial component comprises a joint device with a first joint element and a second joint element, the first joint element being arranged or formed on the tibial plate and the second joint element being arranged or formed on the fixation projection, the first joint element and the second joint element being engaged with each other. Such a joint device in particular allows a predefined pivoting and / or rotation of the joint elements of the joint device which are engaged with each other and cooperate with each other. In particular, the joint device may be configured to establish a hinge joint connection or a ball joint connection between the joint elements.

[0016] Preferably, the first articular element is configured in the form of an articular receptor and the second articular element is configured in the form of an articular process which engages in the articular receptor. A joint device configured in this way can be manufactured in a simple manner and allows flexible alignment of the fixation process to the tibial plate.

[0017] The articular process is preferably spherical and the articular receiver has a hollow-spherical abutment surface for the articular process. This arrangement allows a ball-joint connection with the cooperating articular component to be realized in a simple manner. The fixation projection with the articular ball is therefore rotatable in a simple manner through 360° in the articular receiver with respect to its longitudinal axis and also with respect to the surface normal of the lower surface of the tibial plate, i.e. preferably within a predefined angular range. This angular range can in particular be limited by suitable stops on the fixation projection and / or on the tibial plate.

[0018] Preferably, the articular receptor extends away from the lower surface of the tibial plate, which makes it possible in particular to form the articular receptor on a projection protruding from the lower surface, so that in particular the maximum angular range of pivoting of the fixation lug can be predetermined and maximized in a simple manner.

[0019] The joint receptor is preferably configured rotationally symmetrically. In particular, the joint receptor may be oriented rotationally symmetrically with respect to a surface normal of the lower surface of the tibial plate. Such a joint receptor can be manufactured in a simple manner and allows a ball-joint connection of a fixation lug to the tibial plate.

[0020] In particular, in order to be able to attach the fixation projection to the tibial plate in a simple manner, it is advantageous if the drill holes are formed on the tibial plate, which drill holes pass through the first articular element from the upper surface, so that, for example, a suitable dimension of the fixation projection allows it to be inserted into the drill holes from the upper surface of the tibial plate and pass through the tibial plate.

[0021] If the drill holes form the articular receptors, the tibial component can be constructed particularly compact, in other words the articular receptors can be arranged or formed in the area of ​​the drill holes.

[0022] The fixation projection is preferably dimensioned to pass through the drill hole from the upper surface of the tibial plate, and the articular receiver preferably defines a narrowest portion forming a stop for the second articular element acting in a proximal direction. This configuration makes it possible, in particular, to place the tibial plate on the patient's prepared tibia and then to insert the fixation projection from the upper surface of the tibial plate through the drill hole into the medullary cavity of the tibia. The fixation projection can now be aligned in a desired manner with respect to the tibial plate. In particular, the narrowest portion of the articular receiver prevents the fixation projection from slipping out of the drill hole. In other words, the movement of the fixation projection is limited in the distal direction by the correspondingly configured articular receiver.

[0023] According to a further preferred embodiment, at least one stabilizing projection may be arranged or formed on the underside of the tibial plate, facing away from the underside, laterally adjacent to the fixation projection. In particular, two stabilizing projections may be arranged or formed in the above manner. In particular, the two stabilizing projections may project from the underside of the tibial plate laterally adjacent to the fixation projection in mirror symmetry with each other. In particular, the stabilizing projection may stabilize a first articular element of the articular device and project laterally from the first articular element.

[0024] The at least one stabilization lug is preferably configured as straight or curved. In particular, the stabilization lug may be configured as curved, convex toward the front. In this way, in particular, an optimal stabilization of the connection of the tibial component to the tibia can be achieved, and in particular, rotation of the tibial plate on the tibia can be easily prevented in this way.

[0025] An optimal fixation of the tibial component on the tibia can be achieved in particular by a tibial component with a shaft that can be connected to the fixation lugs in a positive-locking and / or positive-locking manner. In particular, said shaft can be configured to be screwable into said fixation lugs. This allows the surgeon to optimally stabilize the tibial component on the tibia depending on the size of the patient's medullary cavity by selecting a shaft that is adapted to the size of the medullary cavity, in particular its length and cross-section. Here, the shaft can in particular be straight or curved.

[0026] When the fixing protrusion has a male threaded portion formed thereon, the shaft has a fixing protrusion receiving portion for the fixing protrusion, and the fixing protrusion receiving portion has a female threaded portion formed therein that corresponds to the male threaded portion, the fixing protrusion and the shaft can be connected to each other in a simple manner.

[0027] If the fixing element comprises a screw element with an external thread and the drill hole comprises an internal thread corresponding to the external thread originating from the upper surface of the tibial plate, the fixing device can be moved easily from the alignment position to the implantation position (fixing position). In this way, the screw element can be arranged on the tibial plate in a predefined manner and the second clamping element can be pressed against the first clamping element in order to fix the second clamping element to the tibial plate immovably in the fixed position by exerting a pressing force. The screw element may in particular have a tool element receptacle facing away from the upper surface of the tibial plate. This allows the screw element to be screwed into the tibial plate in a simple manner, for example by using a tool.

[0028] A compact construction of the tibial component can be achieved in particular by the fixation elements closing the bores in the implantation position.

[0029] In order to prevent movement of the second joint element relative to the first joint element in the implantation position (fixation position), it is advantageous if the fixation element has a fixation element clamping surface (fixation element fastening surface), which is held in a clamped state against the second joint element in the implantation position.

[0030] Furthermore, it may be advantageous if the fixing element comprises a clamping element, on which the fixing element clamping surface is formed, so that in particular an optimal material combination for clamping the second joint element to the first joint element can be selected, for example independently of the material from which the screw element is made. In particular, the clamping element may be formed separately from the screw element or may form a unit together with the screw element.

[0031] Preferably, the screw element and the clamping element are either integrally formed or formed as two separate parts, the two-part construction of the screw element and the clamping element making it possible to avoid torsional movements of the clamping element relative to the second joint element, in particular when the screw element and the tibial plate are screwed together.

[0032] The clamping element preferably has a screw element abutment surface that faces away from the fixation element clamping surface and abuts against the screw element in the implantation position. In particular, the screw element abutment surface may be configured flat, so that a good contact between the screw element and the clamping element over the entire surface can be ensured in order to clamp and hold the second joint element in a fixed position relative to the first joint element by simply pressing the clamping element with the screw element in a defined manner against the second joint element and applying a pressing force.

[0033] Advantageously, the bore has a clamping element receptacle adjacent to the articular receptacle in the proximal direction for receiving the clamping element, which allows the clamping element to be received in a predefined manner and thus positioned on the tibial plate.

[0034] Advantageously, the bore has a screw element receiving portion adjacent to the clamping element receiving portion in the proximal direction for receiving the screw element, which also allows the screw element to be positioned in or on the bore in a defined manner.

[0035] The cross-sectional area defined by the screw element receiver is preferably larger than the cross-sectional area defined by the clamp element receiver, so that only the clamp element can be inserted into the clamp element receiver, restricting the insertion of the screw element, if the clamp element and the screw element are dimensioned according to their respective receivers. Furthermore, the configuration of the screw element receiver and the clamp element receiver may also limit the maximum movement of the clamp element and the screw element in the distal direction, and in particular the position of the screw element and the clamp element in the implanted position (anchored position).

[0036] The tibial component may be formed in a simple manner if the upper and / or lower surface of the tibial plate is configured to be flat or substantially flat.

[0037] According to the invention, in a knee joint prosthesis system of the type mentioned at the beginning, the at least one tibial component is also configured in the form of one of the above-mentioned tibial components, thereby achieving the object mentioned at the beginning.

[0038] Providing a knee joint prosthesis system with one of the above-mentioned tibial components has the advantage that a knee joint prosthesis can be created that is optimally adapted to the patient, in particular to achieve the kinematic alignment method described at the beginning. Such an optimized alignment of the knee joint replacement can significantly increase the patient's satisfaction, in particular after the implantation of the knee joint prosthesis.

[0039] Advantageously, the knee joint prosthesis comprises at least one meniscal component that can be coupled to the tibial component, the meniscal component having an articular surface that cooperates with the at least one femoral component. This allows an optimal sliding pair between the meniscal component and the femoral component to be formed. Therefore, in particular, a wide variety of knee joint prostheses may be equipped with one of the above-mentioned advantageous tibial components. The meniscal component may be coupled to the tibial component in a stationary or mobile manner.

[0040] To enable optimal adaptation of the knee joint prosthesis to the patient, the knee joint prosthesis system preferably includes multiple shafts (74) of different lengths and / or cross-sections for selectively coupling to the fixation projection of the tibial component. [Brief description of the drawings]

[0041] Hereinafter, preferred embodiments of the present invention will be further described in conjunction with the following drawings.

[0042] [Figure 1] 1 shows a schematic overall perspective view of one embodiment of a knee joint prosthesis. [Diagram 2] FIG. 2 is a schematic, partially exploded, perspective view of the knee joint prosthesis of FIG. 1, illustrating a number of alignment positions of the shaft of the tibial component. [Diagram 3] FIG. 3 shows an exploded view of the tibial component of FIGS. 1 and 2 . [Figure 4]FIG. 4 is a cross-sectional view of the tibial component of FIGS. 1-3, showing the shaft aligned perpendicularly to the upper and lower surfaces of the tibial component. [Diagram 5] 5 is a view similar to FIG. 4, showing the fixation projection pivoted relative to the tibial plate with the shaft in place. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] 1, a knee prosthesis 10 of a first embodiment of a knee prosthesis system 12 is shown diagrammatically. The knee prosthesis 10 is implanted in a patient's knee 14 as a replacement for a degenerated natural knee joint.

[0044] The knee joint prosthesis 10 includes a tibial component 16 and a femoral component 18 that cooperates with the tibial component 16. The tibial component 16 is configured to be secured to a proximal end of a tibia 20. The femoral component 18 is configured to be secured to a distal end of a femur 22. The tibial component 16 and the femoral component 18 are configured to correspond to one another to form the knee joint prosthesis 10.

[0045] 1 and 2 includes an optional meniscal component 24 disposed between the tibial component 16 and the femoral component 18. In this embodiment, the meniscal component 24 may be fixable to the tibial component 16 or may be movable relative to the tibial component 16.

[0046] The meniscal component 24 has an articular surface 26 that cooperates with the femoral component 18. The articular surface 26 abuts against a condylar surface 28 defined by the femoral component 18, and the condylar surface 28 is capable of rolling on and / or sliding along the articular surface 26.

[0047] The tibial component 16 includes a tibial plate 30. In a plan view, the tibial plate 30 is in a mirror-symmetric configuration with respect to a plane of symmetry 32, and is in a substantially U- or kidney-shaped configuration. The tibial plate 30 defines opposed upper and lower surfaces 34 and 36.

[0048] A fixation projection 38 projects from the lower surface 36. The fixation projection 38 is configured to secure the tibial component within a medullary cavity 40 of the tibia 20, which is depicted diagrammatically in dashed lines in FIG.

[0049] The fixation projection 38 is attached to the tibial plate 30 so as to be pivotable and / or rotatable about a longitudinal axis 42 defined by the fixation projection 38 .

[0050] The fixation projection 38 is configured rotationally symmetric or substantially rotationally symmetric with respect to the longitudinal axis 42. The fixation projection 38 includes a distal end 44 that is configured cylindrically or substantially cylindrically.

[0051] The tibial component 16 includes a joint device 46 having a first joint element 48 and a second joint element 50. The first joint element 48 and the second joint element 50 engage with one another, in particular in a partially positive locking manner. The first joint element 48 is disposed or formed on the tibial plate 30. The second joint element 50 is disposed or formed on the fixation projection 38 and defines a proximal end 52 of the fixation projection 38.

[0052] The first articular element 48 (and thus also the fixation projection 38) is arranged or formed in the region of the plane of symmetry 32 of the tibial plate 30. Furthermore, the first articular element 48 (and thus also the fixation projection 38) is arranged or formed in a central or middle region of the lower surface 36 of the tibial plate 30.

[0053] The fixation lug 38 is articulated to the tibial plate 30 by an articulation device 46, in particular in hinge or ball joint fashion.

[0054] In the present embodiment of the tibial component 16, the first articular element 48 is configured in the form of a joint receptacle 54. The second articular element 50 is configured in the form of an articular process 56 which engages with the articular process receptacle 54. In the present embodiment, the articular process 56 is configured in a spherical shape and has a diameter larger than the diameter of the distal end 44. The articular process 54 defines a hollow spherical abutment surface 58. In this way, the articular process 56 configured in the form of a joint ball is rotatable within the articular process receptacle 54 and is pivotable about a center 60 of the articular process 56.

[0055] The articular receptor 54 extends from the underside 36 of the tibial plate 30 and is formed in a sleeve-like projection 62. The articular receptor 54 is of rotationally symmetrical configuration, specifically, rotationally symmetrical about a surface normal 64 of the underside 36 of the tibial plate 30.

[0056] The tibial plate 30 is formed with a bore 66. The bore 66 passes through the tibial plate 30 from the upper surface 34, and in particular through the first articular element 48. The bore 66 thereby comprises the articular receiver 54 formed in the region of the distal end of the projection 62.

[0057] The fixation projection 38 is dimensioned such that its distal end 44 is insertable from the upper surface 34 of the tibial plate 30 into and through the drilled hole 66. Specifically, the fixation projection 38 is dimensioned such that it is insertable until the articular process 56 abuts a narrowest portion 68 defined by the articular receiver 54. The narrowest portion 68 forms a stop 70 for the second articular element 50 acting in the proximal direction.

[0058] Two stabilizing lugs 72 project from the protrusion 62 laterally symmetrically with respect to the plane of symmetry 32. The two stabilizing lugs 72 project in a direction away from the lower surface 36 of the tibial plate 30, similar to the protrusion 62. In the illustrated embodiment, the stabilizing lugs 72 are curved, specifically, convexly curved in the anterior direction. In an alternative embodiment, the stabilizing lugs 72 may be configured in a straight manner.

[0059] The stabilizing projection 72 may in particular prevent rotation of the tibial plate 30 relative to the tibia 20 about the surface normal 64. That is, the stabilizing projection 72 forms a kind of anti-rotation device for the tibial component 16.

[0060] To facilitate better fixation of the tibial component 16 to the tibia 20, in the illustrated embodiment, the fixation projection 38 can be connected in a positive and / or positive locking manner to a shaft 74. The shaft 74 is configured as a substantially elongated cylindrical shape or substantially cylindrical and has a rounded distal end 76.

[0061] The shaft 74 defines a shaft longitudinal axis 78. When the shaft 74 is connected to the fixed projection 38, the shaft longitudinal axis 78 coincides with the longitudinal axis 42, as shown generally in Figures 4 and 5.

[0062] The shaft 74 defines a length 80 from a proximal end to a distal end 76 and a diameter 64 perpendicular to the shaft longitudinal axis 78 .

[0063] Starting from the proximal end 82, a fixation lug receptacle 86 is formed. The fixation lug receptacle 86 has an internal thread 88. The fixation lug receptacle 86 is configured in the form of a blind hole and serves to receive the distal end 44 of the fixation lug 38. The distal end 44 is formed with an external thread 90 that corresponds to the internal thread 88, so that the shaft 74 and the fixation lug 38 can be screwed together.

[0064] The fixation projection 38 may be coupled to the tibial plate 30 as described above by inserting the distal end 44 from the upper surface 34 into the drilled hole 66 until the articular process 56 abuts the abutment surface 58. In this position, the first articular element 48 and the second articular element 50 are movable and therefore alignable relative to one another.

[0065] To secure the fixation projection 38 in a predetermined alignment (e.g., offset by an offset angle 92 relative to the surface normal 64), the tibial component 16 includes a fixation device 94. Using the fixation device 94, the fixation projection 38 may be secured in a fixed or implanted position relative to the tibial plate 30, as shown generally in Figures 4 and 5.

[0066] The fixation device 94 is movable from an alignment position, in which the fixation projection 38 and the tibial plate 30 are movable and alignable relative to one another, to an implantation position, in which, as described above, the fixation projection 38 and the tibial plate 30 are held against relative movement relative to one another in the implantation position.

[0067] The fixing device 94 comprises a fixing element 96 by means of which the second joint element 50 in a fixed position can be fixed relative to the first joint element 48. In other words, in the fixed position, the second joint element 50 can be held, for example by tightening (in a clamped manner), between the fixing element 96 and the first joint element 48.

[0068] The illustrated fixing element 96 is formed in two parts and comprises a screw element 98 and a clamp element 100 .

[0069] The screw element 98 is cylindrical in shape and has external threads 102. The bore 66 originating from the upper surface 34 of the tibial plate 30 has internal threads 104 formed therein corresponding to the external threads 102. A flat surface 106 of the screw element 98 facing away from the fixation projection 38 defines a tool receiving portion 108. The tool receiving portion 108 is configured in the form of a polygonal socket 110.

[0070] The screw element 98 can be screwed into the tibial plate 30 as described above by a screwing tool engageable with the tool receiving portion 108, and in the screwed state the screw element 98 closes the bore 66 in a fixed position.

[0071] The fixing element 96 has a fixing element clamping surface 112, which in the fixing position presses against the second joint element 50 by exerting a pressing force exclusively to clamp it. In order to enable the fixing element clamping surface 112 to abut against the second joint element 50 over its entire surface, if the second joint element 50 is formed by a spherical articular process 56, the fixing element clamping surface 112 is formed in the shape of a hollow sphere corresponding to the articular process 56. The fixing element clamping surface 112 is thus formed on the clamping element 100.

[0072] In an alternative embodiment, the screw element 98 and the clamp element 100 may be integrally formed. In particular, the fastening element 96 may be of monolithic construction.

[0073] 3, in the illustrated embodiment, the clamping element 100 has a flat threaded element abutment surface 114. The threaded element abutment surface 114 is configured to face away from the fixed element clamping surface 112 and abuts the threaded element 98 in the fixed position.

[0074] Proximally adjacent the joint receiver 54 is a clamp element receiver 116. The clamp element receiver 116 defines a larger diameter than the joint receiver 54. The clamp element receiver 116 functions to receive and position the clamp element 100.

[0075] Furthermore, the bore 66 has a screw element receiving portion 118. The screw element receiving portion 118 is adjacent to the clamp element receiving portion 116 in the proximal direction for receiving the screw element 98. The internal threads 104 are formed only in the area of ​​the screw element receiving portion 118.

[0076] The cross-sectional area defined by the screw element receiving portion 118 or the diameter of the screw element receiving portion 118 is greater than the cross-sectional area defined by the clamp element receiving portion 116 or the diameter of the clamp element receiving portion 116 .

[0077] To move the fixation device 94 from the aligned position to the implanted position, the screw element 98 is threaded in a direction toward the spherical articular process 56 until the clamping element 100 exerts a compressive force to clamp the articular process 56 against the articular receptor 54. Conversely, the tibial component 16 or fixation device 94 can be moved from the implanted position back to the aligned position by rotating the screw element 98 in the opposite direction to slightly loosen the threaded connection. This allows the clamping element 100 to release the articular process 56 somewhat to allow rotational and pivotal movement of the fixation process 38 relative to the tibial plate 30.

[0078] In the illustrated embodiment, the upper and lower surfaces 34, 36 of the tibial plate 30 are configured to be flat or substantially flat.

[0079] The upper surface 34 is configured in the form of a tibial articular surface 120. The tibial articular surface 120 forms a sliding pair with the lower surface of the meniscal component 24 due to the movably mounting of the meniscal component 24 on the tibial component 16.

[0080] To allow the knee joint prosthesis 10 to be individually adapted to the patient's physiology, the knee joint prosthesis system 12 may include multiple shafts 74 having different lengths 80 and / or diameters 84 (i.e., cross-sections) that can be selectively coupled to the fixation projection 38 of the tibial component 16.

[0081] Furthermore, in other embodiments, the knee joint prosthesis system 12 may include multiple tibial components 16 with different shapes and / or sizes, multiple femoral components 18 with different shapes and / or sizes, and multiple meniscal components 24 with different shapes and / or sizes. In this way, optimally fitting knee joint prostheses 10 can be provided to people of different body sizes.

[0082] The joint device 46 provided on the tibial component 16 in the above-described embodiment allows the tibial component 16 to be optimally fixed to the tibia 20 regardless of the orientation of the medullary cavity of the tibia 20. The above-described joint device 46 allows for stepless alignment (alignment adjustment) between the shaft 74 and the fixing protrusions arbitrarily arranged on the joint device 46 in order to achieve the kinematic alignment method described at the beginning. This can improve the patient's satisfaction after implantation of the knee joint prosthesis compared to conventional knee joint prostheses. [Explanation of symbols]

[0083] 10 Knee joint prosthesis 12 Knee joint prosthesis system 14 Knee 16 Tibial Component 18 Femoral component 20 Tibia 22 Femur 24 Meniscal Components 26 Articular Surface 28 Condylar surface 30 Tibia Plate 32 Symmetry plane 34 Top side 36 Bottom surface 38 Fixed protrusion 40 Medulla 42 Longitudinal axis 44 Distal end 46 Joint Device 48 First joint element 50 Second joint element 52 Proximal end 54 Joint Receptors 56 Articular process 58 Contact surface 60 center 62 Protrusion 64 surface normal 66 perforation 68 Narrowest part 70 Stopper 72 Stabilizing projection 74 Shaft 76 Distal end 78 Shaft Longitudinal Axis 80 Length 82 Proximal end 84 diameter 86 Fixing protrusion receiving part 88 Female thread 90 Male thread 92 Declination 94 Fixation device 96 Fixed elements 98 Screw elements 100 Clamping Elements 102 Male thread 104 Female thread 106 Flat surface 108 Tool Receptacle 110 Polygonal Socket 112 Fixed element clamping surface 114 Screw element contact surface 116 Clamping element receiving portion 118 Screw element receiving portion 120 Tibial Articular Surface

Claims

1. A tibial component (16) for a knee joint prosthesis (10), wherein the tibial component (16) comprises a tibial plate (30) having an upper surface (34) and a lower surface (36), and a fixing projection (38) protruding from the lower surface (36) so as to be insertable into the medullary cavity (40) of the tibia (20) for fixing the tibial component (16) to the tibia (20), wherein the fixing projection (38) is attached to the tibial plate (30) so as to be rotatable and / or turnable around the longitudinal axis (42) of the fixing projection (38), wherein the tibial component (16) comprises a fixing device (94) for fixing the fixing projection (38) at the implantation position, wherein the fixing device (94) is movable from an alignment position in which the fixing projection (38) and the tibial plate (30) are movable and alignable relative to each other to the implantation position in which the fixing projection (38) and the tibial plate (30) are held relative to each other so as not to move relative to each other, wherein the fixing device (94) comprises a fixing element (96), wherein a second joint element (50) in the implantation position is clamped and held between the fixing element (96) and a first joint element (48), characterized in that at least one stabilizing projection (72) is arranged or formed on the lower surface (36) in a direction away from the lower surface (36) adjacent to the lateral direction of the fixing projection (38). Tibial component.

2. The fixing projection (38) is (a) arranged or formed in the region of the symmetry plane (32) of the tibial plate (30) and / or (b) arranged or formed in the central region or the center region of the lower surface (36) of the tibial plate (30) and / or (c) configured to be rotationally symmetric or substantially rotationally symmetric with respect to the longitudinal axis (42) and / or (d) attached to the tibial plate (30) in a jointed manner, in particular in a hinge joint manner or a ball joint manner. The tibial component according to claim 1, characterized in that.

3. The tibial component (16) comprises a joint device (46) having the first joint element (48) and the second joint element (50), wherein the first joint element (48) is arranged or formed on the tibial plate (30). The second joint element (50) is disposed or formed on the fixing projection (38), the first joint element (48) and the second joint element (50) are engaged with each other, The tibial component according to claim 1 or claim 2, characterized in that.

4. The first joint element (48) is configured in the form of an articular receptacle (54), The second joint element (50) is configured in the form of an articular projection (56) that engages with the articular receptacle (54), The tibial component according to claim 3, characterized in that.

5. (a) The articular projection (56) is spherical, and the articular receptacle (54) has a hollow spherical contact surface (58) for the articular projection (56), and / or, (b) The articular receptacle (54) extends in a direction away from the lower surface (36) of the tibial plate (30), and / or, (c) The articular receptacle (54) is configured to be rotationally symmetric, particularly with respect to the normal (64) of the lower surface (36) of the tibial plate (30). The tibial component according to claim 4, characterized in that.

6. A perforation (66) is formed on the tibial plate (30), and the perforation (66) penetrates the tibial plate (30) so as to pass through the first joint element (48) from the upper surface (34), In particular, The first joint element (48) is configured in the form of an articular receptacle (54), The second joint element (50) is configured in the form of an articular projection (56) that engages with the articular receptacle (54), (a) The perforation (66) constitutes the articular receptacle (54), and / or, (b) The fixing projection (38) has a dimension that allows it to pass through the perforation (66) from the upper surface (34) of the tibial plate (30), and the articular receptacle (54) defines a narrowest portion (68) that forms a stopper (70) for the second joint element (50) acting in the proximal direction. The tibial component according to claim 3, characterized in that.

7. (a) Adjacent to the lateral direction of the fixing projection (38), two of the stabilizing projections (72) are disposed or formed on the lower surface (36) in a direction away from the lower surface (36) of the tibial plate (30), and / or, (b) The at least one stabilizing projection (72) is configured linearly, or in a curved shape, particularly in a shape that curves convexly forward. The tibial component according to claim 1 or claim 2, characterized in that.

8. The tibial component (16) comprises a shaft (74), The shaft (74) can be connected to the fixing projection (38) in a forced locking manner and / or a positive locking manner, in particular threadably. In particular, a male thread portion (90) is formed on the fixing projection (38). The shaft (74) has a fixing projection receiving portion (86) for the fixing projection (38). A female thread portion (88) corresponding to the male thread portion (90) is formed in the fixing projection receiving portion (86). The tibial component according to claim 1 or claim 2, characterized in that.

9. The fixing element (96) (a) comprises a screw element (98) having a male thread (102), a perforation (66) is formed on the tibial plate (30), the perforation (66) penetrates the tibial plate (30) so as to pass through the first joint element (48) from the upper surface (34), the perforation (66) comprises a female thread (104) corresponding to the male thread (102) starting from the upper surface (34) of the tibial plate (30), and / or (b) closes the perforation (66) at the implantation position, the perforation (66) is formed on the tibial plate (30) and penetrates the tibial plate (30) so as to pass through the first joint element (48) from the upper surface (34), and / or (c) has a fixing element clamping surface (112) that is clamped and held against the second joint element (50) at the implantation position. The tibial component according to claim 1 or claim 2, characterized in that.

10. The fixing element (96) comprises a clamping element (100). The fixing element clamping surface (112) is formed on the clamping element (100). The tibial component according to claim 9, characterized in that.

11. The screw element (98) and the clamping element are integrally formed or formed as two separate parts. The tibial component according to claim 10, characterized in that.

12. The clamping element (100) has a screw element abutting surface (114), which is particularly flat. The screw element abutting surface is configured to face the opposite side of the fixing element clamping surface (112) and abut against the screw element (98) at the implantation position. The tibial component according to claim 10, characterized in that...

13. The first joint element (48) is configured in the form of an articular receptacle (54), the second joint element (50) is configured in the form of an articular projection (56) that engages with the articular receptacle (54), the perforation (66) has a clamp element receiving portion (116) adjacent to the articular receptacle (54) in the proximal direction for receiving the clamp element (100), in particular, the perforation (66) has a screw element receiving portion (118) adjacent to the clamp element receiving portion (116) in the proximal direction for receiving the screw element (98), more particularly, the cross-sectional area defined by the screw element receiving portion (118) is larger than the cross-sectional area defined by the clamp element receiving portion (116), The tibial component according to claim 10, characterized in that...

14. A knee joint prosthesis system (12) comprising at least one femoral component (18) for fixing to the distal end of the femur (22) and at least one tibial component (16) for fixing to the proximal end of the tibia (20), wherein the at least one femoral component (18) and the at least one tibial component (16) are configured to correspond to each other to form a knee joint prosthesis (10), characterized in that the at least one tibial component (16) is configured in the form of the tibial component (16) according to claim 1 or claim 2. Knee joint prosthesis system.

15. (a) The knee joint prosthesis (10) comprises at least one meniscus component (24) that can be coupled to the tibial component (16), and the meniscus component (24) has an articular surface (26) that cooperates with the at least one femoral component (18), and / or (b) The knee joint prosthesis system (12) comprises a plurality of shafts (74) having different lengths (80) and / or cross-sections for selectively coupling to the fixing projections (28) of the tibial component (16), The knee joint prosthesis system according to claim 14, characterized in that...

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