CH709776B1 - Correction inlay for a total knee prosthesis, method for its production and total knee prosthesis with correction inlay. - Google Patents

Abstract

The disclosure relates to an inlay system (1a, 1b, 1c) for a total knee prosthesis. The inlay system comprises a normal inlay (1a) or a normal inlay dataset defining the geometric shape of a normal inlay (1a), the normal inlay (1a) having a tibial-side interface structure for mounting on a tibia and one of the tibial side surface structure opposite (10a, 10b, 10c) for flexible interaction with a femoral implant. The geometric shape of the normal inlay (1a) corresponds to a corrected postoperative mechanical leg axis without consideration of corrections required by a patient-specific soft-tissue situation. The inlay system (1a, 1b, 1c) further comprises at least one correction inlay (1b, 1c), wherein a geometric shape of the at least one correction inlay (1b, 1c) has a geometrical shape, which with respect to the normal inlay (1a) is modified for an intraoperative correction due to the patient-specific soft tissue situation. The disclosure further relates to a total knee prosthesis with a correction inlay and a method for producing a total knee prosthesis.

Description

description

Technical Field The present invention relates to the field of endoprosthetics, in particular total knee arthroplasty. It relates to an inlay system with a correction inlay for a total knee prosthesis, as well as a total knee prosthesis with a correction inlay. The invention further relates to a method for producing a correction inlay.

Background of the Prior Art The primary prostheses of today are each comprised of a femur and a tibial component which, unlike the hinged prosthesis, are not interconnected by artificial mechanical aids. As with the natural knee joint, the flexible connection and flexible cooperation for extension and flexion by soft tissues, i. Ribbons and muscles made.

Before the prosthesis components on the femur or the tibia can be fixed by jamming, wedging and / or bone cement, femur and tibia must be brought by means of bone saws and other instruments in the form suitable for the prosthesis. For this purpose, the manufacturers of the knee prosthesis tools and instruments are offered to make the necessary corresponding bone cuts on the femur and tibia, the so-called osteotomies, with the necessary accuracy.

The determination of the required bone sections as well as the selection and partially patient-specific production of the implant components takes place in a preoperative surgical planning based on three-dimensional imaging techniques, such as X-ray computed tomography, where bony landmarks serve as reference points.

For the operation planning as well as for the operation itself, various techniques and "philosophies" are known, which differ by the reference points / landmarks used and the order of cuts and femur and tibia ("femur first" versus "Tibia First), each of the methods has specific advantages and disadvantages.

For all procedures, consideration of the patient specific soft tissue situation, i. The arrangement, length and tension / elasticity of the ligaments and muscles is a particular challenge and is problematic in that it is important on the one hand for a correct postoperative (corrected) leg axis, but can not be taken into account in the operation planning. Therefore, interoperative corrections or deviations from the original surgical planning are usually required. These subsequent corrections or deviations entail prolonged surgery time and cause unnecessary bone loss.

DESCRIPTION OF THE INVENTION It is therefore an object of the invention to improve basically known knee implants with regard to the intraoperative consideration of the soft tissue situation (ligamentous situation) and to enable a good consideration of corrections caused by the soft tissue situation. Correct consideration of the soft-tissue situation avoids or reduces subsequent complications, in particular pain, premature wear of the knee implant and, in many cases, the need for further corrective surgery. According to the current state, instabilities and an incorrect or uneven force distribution due to insufficient consideration of the patient-specific soft-tissue situation represent the most common cause of failed knee arthroplastics, which often necessitate a new operation for the purpose of correction.

The stated object is solved by the features of the independent claims. The dependent claims, as well as the following description and figures, define advantageous exemplary embodiments.

According to a first aspect, the object is achieved by an inlay system for a total knee prosthesis.

The inlay system comprises a normal inlay or a normal inlay data set defining the geometric shapes of a normal inlay. The normal inlay comprises a tibial-side interface structure for mounting on a tibia and a femoral-side interface structure opposite the tibial-side interface structure for flexible interaction with a femoral implant. The geometric shape of the normal inlay is determined in accordance with a corrected postoperative mechanical leg axis without consideration of corrections required by a patient-specific soft-tissue situation. This is preferably done in a preoperative surgical planning. The inlay system furthermore comprises at least one correction inlay which is preferably integral along the leg axis, wherein a geometrical shape of the at least one correction inlay is based on the geometrical shape of the normal inlay and the at least one correction inlay is in each case one with the normal one. Inlay comprises identical tibial-sided interface structure and a femoral-side interface structure for flexible interaction with the same femoral implant as the normal inlay. The at least one correction inlay has a geometric shape which is modified relative to the normal inlay for an intraoperative correction on the basis of the patient-specific soft-tissue situation.

The inventive inlay system is based on a total knee prosthesis, in which the femur implant, typically by jamming, wedging and / or bone cement, attached to the correspondingly resected femur or mounted. The actual joint function for extension and flexion of the knee is realized by the flexible interaction of the femoral implant with the inlay (also referred to as an insert) in basically known manner. The actual connection of the implant components and thus the cohesion of the prosthesis, as described above, realized by the natural soft tissues (ligaments, muscles). The inlay can be fixed or mounted in a known manner either directly or via an intermediate element (back or tibia base) on the tibial cut. The femoral implant is typically made of a metal, such as titanium, CrCo alloy or other corresponding metal alloy or ceramic, but may in principle also be made of plastic. The inlay is typically made of plastic.

The femur-side interface structure of the at least one correction inlay typically coincides exactly with that of the normal inlay in its geometric shape, as is the case with the tibial-side interface structure. However, it may also have low geometric deviations in view of the required flexible interaction with the femoral implant.

In a basic variant and in its simplest form, the inlay system according to the invention correspondingly consists of two different inlays, namely a normal inlay and a correction inlay. The principle of the correction inlay based on the geometrical shape of the normal inlay and the design according to the invention of the femoral-side and the tibial-sided interface structure cause the standard inlay and the at least one correction inlay to be used without any need for other changes or additional steps the operation can be used alternatively.

Thus, the surgeon can spontaneously use either the normal inlay or a correction inlay according to the patient-specific soft tissue situation, the decision is to make it only in the course of the operation.

The inlay system may be provided for compatibility with all common inlay standards such as Post-Stabilized, Cruciate Retaining, Lateral Pivot, Medial Pivot, Untrakonkruente, Mobile Bearing, Fixbearing.

To detect the need for any corrections due to the patient-specific soft tissue situation and to determine the extent of these corrections measuring instruments, spacers and sample inlays can be used in a known manner.

If the inlay to be implanted-be it as a standard part or patient-specific-is prepared before the operation, both the normal inlay and the at least one correction inlay are physically present and present during the operation, so that the surgeon has the appropriate inlay only by means of sample inlay selects.

The machine-readable record of such an embodiment may be stored in a non-transitory computer-readable medium. The computer readable medium may be, for example, a floppy disk, a CD-ROM or the random access memory (RAM) of a computer.

In an alternative embodiment, corrections for taking into account the patient-specific soft tissue situation on the side of the femoral implant instead of on the side of the inlay. In such an embodiment, instead of an inlay system of the type described, a Fermurimplantat system is used with a normal femoral implant or a normal femur implant defining the geometric shape of a normal femoral implant data set. The femoral implant system then comprises at least one correction femur implant, wherein a geometric shape of the at least one correction femur implant based on the geometric shape of the normal femur implant and the at least one correction femur implant, in particular one with the normal femoral implant femurseitige interface structure and a tibial-sided interface structure for flexible interaction with the same inlay as the normal femoral implant. In the following, for the description of specific embodiments and the embodiments of an inlay system as previously described, with an implementation for a femur implant system in an analogous manner is possible.

In some embodiments, intraoperative correction includes a varus algus correction and / or a slope and / or rotation correction due to the patient specific soft tissue situation. In particular, the intraoperative correction may include a varus / valgus correction, and optionally additionally one or both of a slope correction and a femur rotation.

Varus / valgus corrections are the most common intraoperative corrections. Basically, by means of the correction inlays according to the invention, with suitable modified geometries of these inlays, alternatively or additionally, further and / or other intraoperative corrections are made possible. For example, an undesired femur rotation, slope, or a combination of two or more sizes could be corrected. When correcting the slope, the correction does not take place in the medial-lateral direction as in varus / valgus correction, but at right angles to it in the dorsal-ventral direction.

In some embodiments, the inlay system comprises a plurality of correction inlays, wherein the individual inlay with respect to the normal inlay each have a differently modified geometric shape for different intraoperative corrections due to the patient-specific soft tissue situation.

Alternatively, the inlay system may also include a plurality of correction inlay data sets defining the geometric shape of a plurality of correction inlays. In this case, the individual geometric shapes with respect to the geometric shape of the normal inlay are each modified for different intraoperative corrections on account of the patient-specific soft-tissue situation. The geometric shape of the at least one correction inlay is a geometric shape defined by at least one of the correction inlay data sets.

In the first of these alternatives, the inlay system according to the invention comprises a physically existing plurality of correction inlays as a set of correction inlays from which the surgeon selects a most suitable one during the operation. In the case of the second alternative, this set of correction inlays initially exists only in the form of several data sets. Only the correction inlay actually required, or a narrower selection of eligible inlays, is physically produced.

In a further variant, the plurality of correction inlay data sets is not present in the form of separate data sets, but in the form of a generic data set and one or more - also typically machine-readable - stored calculation rules for calculating the geometric shape of various correction inlays on the generic dataset, for example for varus algus corrections.

In a further variant, the inlay system comprises at least one adjustable inlay, wherein the adjustable inlay comprises an adjustment by means of which its geometric shape can be changed continuously or stepwise, wherein different geometric shapes correspond to different correction inlays. In this case, only one inlay can always be physically present, which has corresponding adjustment devices by means of which its geometric shape can be changed continuously or stepwise, so that the same physically existing inlay can be configured both as a normal inlay and as a correction inlay. In further variants, different correction inlays are present for different corrections, wherein the extent of the correction is determined in each case by setting on the correction inlay. For example, an inlay system may include a normal inlay, a first correction inlay with an adjustable angle in the range of 0.5 ° to 4 ° varus, and a second correction inlay with an adjustable angle in the range of 0.5 ° to 4 ° valgus , Each of the different possible settings corresponds to a correction inlay. The limiting case of continuous adjustability corresponds to an infinite number of separate infinitesimal grading correction inlays. Other aspects of such a system will be discussed in the context of the embodiments and the figures.

[0027] In some such embodiments, the plurality of correction inlays or correction inlay datasets comprises a set of correction inlays or correction inlay datasets for correction angle graded intraoperative varus algus corrections and / or graded slopes. Correction. In this case, the set of correction inlays or correction inlay data sets can be designed, for example, for varus / algus corrections with a correction angle of up to 3 °.

In some embodiments, the set of correction inlays or correction inlay data sets comprises four correction inlays or four correction inlay data sets, in particular exactly four correction inlays or correction inlay data sets. The four correction inlays or correction inlay datasets are designed for a correction angle of 1 ° and 3 ° varus and 1 ° and 3 ° valgus, respectively. In such an embodiment, the inlay system, including the normal inlay and the normal inlay data set respectively, comprises at least five inlays or five data sets. This appears to be sufficient in many cases from a practical point of view. As an alternative or in addition to correction inlays for varus / valgus correction, the inlay system may further comprise correction inlays or correction inlay datasets for further corrections, in particular a femur rotation and / or a slope correction.

In some embodiments, the tibial side interface structure is designed for direct mounting on the tibia. In further alternative embodiments, the tibial-side interface structure is designed for mounting on a separate tibial implant. In particular, the tibial implant may be a so-called back or a tibial base.

Between the inlay and the tibia - or optionally present separate tibial implant - are preferably no other components. The inlay is thus arranged either directly on the tibial cut or directly on the optionally present separate tibial implant.

In some embodiments, the geometric shape of the normal inlay and the at least one correction inlay is patient specific.

According to a further aspect, the object underlying the invention is achieved by a total knee prosthesis. The total knee prosthesis includes a preferably one-piece correction inlay along the leg axis, the correction inlay comprising a tibial-side interface structure for mounting on a tibia and a femoral-side interface structure opposite the tibial-side interface structure for flexible cooperation with a femoral implant. In this case, the geometric shape of the correction inlay is based on a geometric shape of a normal inlay, wherein the geometric shape of the normal inlay is determined by a corrected postoperative mechanical axis of the leg without consideration of corrections required by a patient-specific soft-tissue situation. The shape of the normal inlay is preferably determined in a preoperative surgical planning. The correction inlay has a shape that is modified compared to the geometric shape of the normal inlay for intraoperative correction on the basis of the patient-specific soft-tissue situation. The femoral implant of the total knee prosthesis comprises a femoral-side interface structure for mounting on a femur and a tibial-side interface facing the femoral-side interface structure.

Structure. The tibial-sided interface structure is designed to interact flexibly with the femoral-side interface structure of the correction inlay.

According to a further aspect, the object underlying the invention is achieved by a method for producing an inlay system for a total knee prosthesis. The method comprises providing a normal inlay or a normal inlay dataset defining the geometric shape of a normal inlay, the normal inlay comprising a tibial-side interface structure for mounting on a tibia and a femoral-side interface structure opposite the tibial-side interface structure for flexible cooperation with having a femoral implant. The geometric shape of the normal inlay is determined, preferably in a preoperative surgical planning, corresponding to a corrected postoperative mechanical leg axis without consideration of the correction required by a patient-specific soft-tissue situation. The method further comprises producing at least one correction inlay which is preferably integral along the leg axis, wherein a geometric shape of the at least one correction inlay is based on the geometric shape of the normal inlay and the at least one correction inlay in each case one with the Normal inlay comprises identical tibial-sided interface structure and a femoral-side interface structure for flexible interaction with the same femoral implant as the normal inlay. The at least one correction inlay has a geometric shape, which is modified with respect to the normal inlay for an intraoperative correction on the basis of the patient-specific soft-tissue situation.

A method for implanting an inlay as part of a total knee prosthesis which does not form part of the invention comprises providing a normal inlay or a normal inlay dataset defining the geometric shape of a normal inlay. The normal inlay has a tibial-side interface structure for mounting on a tibia and a femoral-side interface structure opposite the tibial-side interface structure for flexible interaction with a femoral implant. The geometric shape of the normal inlay is determined, preferably in a preoperative operation planning, corresponding to a corrected postoperative mechanical leg axis without consideration of corrections required by a patient-specific soft-tissue situation.

The method further comprises providing a correction inlay which is preferably integral along the leg axis or at least one correction inlay data record defining the geometric shape of a correction inlay. The geometric shape of the correction inlay is based on the geometric shape of the normal inlay, and the at least one correction inlay comprises in each case a tibial-side interface structure identical to the normal inlay and a femoral-side interface structure for flexible interaction with the same femoral implant as the normal femoral implant. Inlay. In this case, the at least one correction inlay has a geometric shape, which is modified with respect to the normal inlay for an intraoperative correction on the basis of the patient-specific soft-tissue situation.

The method further comprises an intraoperative assessment of the patient-specific soft tissue situation, selecting the inlay to be implanted as a standard inlay or correction inlay as a function of the patient-specific soft tissue situation and implanting the selected inlay. Additionally or alternatively, the correction of bone defects is possible in this way.

In embodiments in which the method comprises first producing a normal inlay data set and a correction inlay data set, the method further comprises physically preparing the normal inlay or the correction inlay prior to implantation.

In some embodiments, the method includes providing a plurality of correction inlays, wherein each of the single inlay correction inlays has a different modified geometric shape relative to the normal inlay for different intraoperative correction due to the patient specific soft tissue situation. Alternatively, the method includes providing a plurality of correction inlay data sets defining the geometric shape of a plurality of correction inlays. The individual geometric shapes are modified with respect to the geometric shape of the normal inlay in each case for different intraoperative corrections due to the patient-specific soft tissue situation.

In these embodiments, the method comprises selecting an inlay to be implanted as a standard inlay or one of the plurality of correction inlays depending on the patient-specific soft tissue situation and implanting the selected inlay.

BRIEF EXPLANATION OF THE FIGURES The invention will be explained in more detail below on the basis of exemplary embodiments in conjunction with the drawing.

Fig. 1a shows a schematic representation of the human leg skeleton in the preoperative and

Fig. 1b in the postoperative state, wherein in each case a left leg with the relevant axes is shown in a view from the front.

2 shows a schematic representation of a femur and a tibia with a total knee prosthesis.

FIGS. 3a, 3b, 3c show an inlay system with a normal inlay and two correction inlays.

FIGS. 4a, 4b, 4c show a further inlay system with a normal inlay and two correction inlays.

FIGS. 5a, 5b, 5c show a further inlay system with a normal inlay and two correction inlays.

Figures 6a, 6b show schematically a varus / valgus correction with alternative use of a correction inlay and a correction femur implant.

Fig. 7 shows schematically a two-part tibial implant with a medial and a separate lateral

Inlay component.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1a and 1b show, in a schematic representation, the human leg skeleton in the preoperative (FIG. 1a) and in the postoperative state with inserted primary total knee prosthesis (FIG. 1b), wherein in each case a left leg with the anatomical axes of tibia aT and femur aF, the HKA axis and the valgus angle α is shown.

FIG. 2 shows a schematic view of a postoperative knee joint with correct alignment of the main knee axis HKA with a section of the femur F and the tibia T corresponding to FIG. 1. The total knee prosthesis consists of an inlay 1, a metal back or tibia base 2 placed on the tibial cut, and a femur implant 3. As can be seen from FIG. 2, the thickness of the inlay 1 is not constant. Instead, the thickness dm in the medial area is smaller here than the thickness di in the lateral area. The contact between the inlay 1 and the femur implant 3 is here simplified assumed as two-point contact with a medial contact point Cm and a lateral contact point Ci, where a denotes a distance between the contact points. Accordingly, there is a height difference d = d | dm between the two contact points. The exact design of the inlay 1 and the height difference d in Fig. 2 are to be regarded as exemplary and differ in practice from patient to patient.

The side of the inlay 1 carrying the femur-side interface structure is referred to as the upper side 10 and the side of the inlay 1 bearing the tibial-side interface structure as the lower side 11.

3a, 3b, 3c together show a set of inlays 1a, 1b, 1c for alternative use as part of a total knee prosthesis in a schematic representation. In FIGS. 3a, 3b, 3c it is assumed that the orientation of the femur and the femur implant corresponds in each case to that of the femur F and the femur implant 3 from FIG. 2 and is unchanged between FIGS. 3a, 3b, 3c, and thus as Reference serves. In addition, the medial and lateral contact points Cm and C | and an axis of symmetry A is drawn in which corresponds to the postoperative main knee axis HKA according to FIG. 1b with correct balancing.

In this case, the inlay 1a shown in FIG. 3a is a normal inlay and corresponds for example to the inlay 1 from FIG. 2 with the medial thickness da_m and the lateral thickness da_ |.

The further inlays 1b, 1c shown in FIGS. 3b and 3c are correction inlays in which the upper sides 10b, 10c are modified in each case relative to the upper side 10a of the normal inlay 1a. Thus, the medial thickness db-m of the correctional inlay 1b is smaller compared to the normal inlay 1a, the lateral thicknesses da-i, db-1 being equal. Correspondingly, the height difference between the lateral part and the medial part of the upper side 10b to the lower side 11 is greater than between the lateral part 10a_i and the medial part 10a_m in the case of the normal inlay 1a.

The medial thickness dc-m of the correction inlay 1c is larger with an unchanged lateral thickness di compared to the normal inlay 1a, wherein the lateral thicknesses da_i, dc-i are again the same. Correspondingly, the difference in height between the lateral part and the medial part 1 of the upper side 10c to the lower side 11 is smaller than between the lateral upper side 10a_i and the medial upper side 10a_m larger in the case of the normal inlay 1a.

Due to the respective identical contact points Cm and Ci results when using the correction inlays 1b or 1c each an inclination of the bottom 11 and thus also the tibial-side interface structure and connected to this tibia, the correction angle from the correction inlays 1b causes a tilting of the tibia compared to the femur in the medial direction and the correction angle ac of the correction inlay 1c causes a tilting of the tibia in comparison to the femur in the lateral direction.

By selecting a suitable inlay, the surgeon can make a varus / valgus correction corresponding to the angle between the femur and the tibia during the operation as a function of the soft tissue situation. In a similar way, a slope correction can be made by appropriately designed correction inlays. In this way, a correct postoperative balancing and in particular a correct postoperative course of the HKA axis according to FIG. 1b can be ensured at least to a good approximation. Sometimes, however, the correction also deliberately deviates from the HKA axis in order to achieve optimal ligament balance and thus a correct consideration of the patient-specific soft tissue situation.

4a, 4b, 4c together show another set of inlays 1a, 1b ', 1c' for alternative use as part of a total knee prosthesis in a schematic representation. In this case, the normal inlay 1a 'shown in FIG. 4a is identical to the normal inlay 1a of FIG. 3 and only shown again for better understanding.

In contrast to the correction inlays 1b, 1c, in the case of the correction inlays 1b ', 1c', the tilting of the tibia relative to the femur does not take place due to an altered course of the upper side 10, which is here identical in each case. Instead, the body of the correction inlays 1b '1c' between the medial and distal side is wedge-shaped, which also results in a tilting of the tibia relative to the femur by correction angle ab or ac. It is also possible to combine both approaches according to FIGS. 3 and 4.

FIGS. 5a, 5b, 5c show an inlay system corresponding to FIGS. 4a, 4b, 4c, wherein the tibial-side interface structure 11 is shown in identical (horizontal) orientation in each case. Correspondingly, the correction inlays according to FIGS. 5b, 5c each have a tilt of the femur-side interface structure 10 relative to the tibial-side interface structure 11.

For the realization of different correction angles, instead of various correction inlays, an adjustable correction inlay can also be provided. This can have an implanted state to the femur and a component facing in the implanted state of the tibia, wherein the components to each other - for example by means of a displaceable in lateral-medial direction and arranged between said components wedge element - mutually angularly (see FIG. 4). It is also possible to make the lateral thickness di and / or the medial thickness dm of the inlay adjustable (cf. FIG. 4).

The setting of such an adjustable inlay, for example, via a threaded pin by means of a suitable tool - in the simplest case a screwdriver - done. In this way, the inlay can be set correctly by the surgeon immediately during the operation due to the patient-specific soft tissue situation. Such a configuration is also advantageous in view of any corrections required postoperatively. For this purpose, the inlay can be designed such that an adjustment element, that is, for example, a threaded pin, is accessible percutaneously for a corresponding adjustment tool. In this case, for a possible correction, only access to the setting tool which can be produced with means and methods of minimally invasive surgery is required, but not a renewed opening of the knee joint and possibly an exchange of the originally inserted inlay.

Another embodiment is an e.g. electrically operated actuator - for example in the form of a micromotor - integrated as an integral part of the inlay, so that a separate adjustment tool is unnecessary. The adjustment can then take place, both during the operation and postoperatively, by controlling the actuator by means of remote control.

In further variants, the knee implant, ie the femur implant, the inlay and / or an intermediate piece between the inlay and the tibia (back or tibia base) comprises a sprung mechanism or an element filled with a fluid (gas or liquid), which can be changed continuously or stepwise in order to achieve the desired ligamentous situation. Different geometrical shapes correspond to different correctional inlays.

An adjustable or in its geometric shape variable correction inlay is not necessarily integral along the leg axis, but may comprise a plurality of relatively movable components or components.

Optionally, an integrated sensor or a plurality of sensors can be provided in the knee implant. Such a sensor may detect such data as pressure or pressure distribution, angular position and / or wear of the materials. The data determined by the sensor can optionally be stored or temporarily stored in a memory likewise integrated in the implant. For further processing such as display, graphical representation, statistical evaluation, comparison with setpoints, etc., an external evaluation device can be provided. Communication between sensor (s) and external evaluation device preferably takes place without galvanic coupling, e.g. by radio interface, near-field communication (LF), capacitive coupling, etc. One or more sensors may e.g. integrated into the inlay, the femoral implant or an intermediate piece between the inlay and the tibia (back or tibia base).

FIGS. 3a to 3c, 4a to 4c and 5a to 5c each relate to an inlay for a total knee prosthesis of the left knee. The same relationships are mirrored for the right knee.

In the illustrations, exaggeratedly large tilt angles have been selected for clarity. Practically relevant values for varus or valgus tilting are in a typical range of 1 ° to 3 °, but may be higher.

The inlays 1a, 1b, 1c and 1a ', 1b', 1c 'can be in physical form when performing total knee arthroplasty. Furthermore, the correction inlays may each be in different embodiments, e.g. for a correction of 1 ° each and 3 ° varus or valgus. During surgery, the surgeon then only needs to select the appropriate inlay from the set of inlays, where he can test the balance for different inlays.

Alternatively, the inlays are not physically available, but in the form of data sets and the required inlay or a plurality of inlays for alternative use is or are - as explained above - produced directly during the operation.

Furthermore, the inlays are each here taken transversely to the leg axis as one piece. In alternative embodiments, they can also be made in several pieces transversely to the leg axis. In particular, they may be designed in two pieces with a medial and a lateral inlay component. If appropriate, one and the same medial (lateral) component can also be combined with various alternative lateral (medial) components in the manner of a construction kit in order to realize different varus-algus corrections, slope corrections or a combination thereof. This is shown schematically in FIG. 7, wherein the inlay has a medial inlay component 1-m and a lateral inlay component 1-1. In this case, the inlay comprises a lateral element 1-1 and a medial element 1-m other than the lateral element 1-1. An identical medial element 1-m can in this case be combined with various lateral elements 1-1 in order to realize a normal inlay or a correction inlay in this way. In an analogous manner, an identical lateral element 1-1 could be combined with different medial elements 1-m.

For additional or alternative intraoperative corrections, such as a femur rotation and / or a slope correction, additional correction inlays may be provided in a manner analogous to the correction inlays 1b, 1c.

Figs. 6a and 6b illustrate schematically the making of a varus / valgus correction either by means of a correction inlay as previously described with reference to Figs. 3a, 3b, 3c and 4a, 4b, 4c ( Fig. 6a), or by means of a correction femur implant (Fig. 6b). In FIG. 6a, the inlay 1 'is a correction inlay as described above, which has a laterally greater thickness than a normal inlay by way of example. In FIG. 6 b, a normal inlay 1 is used as the inlay, while the femur implant 3 'is a correction femur implant which has an increased thickness in the lateral region 31', which results in substantially the same effect as through the correction inlay 1 'in Fig. 5a.

Claims (12)

claims 1. inlay system (1a, 1b, 1c, 1a ', 1b', 1c ') for a total knee prosthesis (1, 2, 3), the inlay system comprising: a) a normal inlay (1a, 1a') or a normal inlay dataset defining the geometric shape of a normal inlay (1a, 1a '), the normal inlay dataset being stored in a non-transitory computer readable medium, the normal inlay (1a, 1a ') comprises a tibial-side interface structure for mounting on a tibia (T) and a femoral-side interface structure (10) opposite the tibial-side interface structure for flexible cooperation with a femoral implant (3); wherein the geometric shape of the normal inlay (1a, 1a ') is determined, preferably in a preoperative operation planning, corresponding to a corrected postoperative mechanical leg axis without taking account of corrections required by a patient-specific soft-tissue situation; b) at least one correction inlay (1b, 1c, 1b ', 1c'), wherein a geometric shape of the at least one correction inlay (1b, 1c, 1b ', 1c') on the geometric shape of the normal inlay (1a, 1a ') and the at least one correction inlay (1b, 1c, 1b', 1c ') has a tibial-side interface structure (11) identical to the normal inlay (1a, 1a') and a femoral-side interface structure for flexible interaction with the same femoral implant as the normal inlay; wherein the geometric shape of the at least one correction inlay (1b, 1c, 1b ', 1c') is modified relative to the normal inlay (1a, 1a ') for an intraoperative correction on the basis of the patient-specific soft-tissue situation. 2. Inlay system (1a, 1b, 1c, 1a ', 1b', 1c ') according to claim 1, wherein the intraoperative correction due to the patient-specific soft tissue situation, a varus / valgus correction and / or a slope and / or rotation Correction includes. 3. Inlay system (1a, 1b, 1c, 1a ', 1b', 1c ') according to claim 1 or 2, wherein the inlay system (1a, 1b, 1c, 1a', 1b ', 1c') either a A plurality of correction inlays (1b, 1c, 1b ', 1c'), wherein the individual correction inlays (1b, 1c, 1b ', 1c') each have a different modification with respect to the normal inlay (1a, 1a ') have geometric shape for various intraoperative corrections due to the patient specific soft tissue situation; or a plurality of correction inlay data sets defining the geometric shape of a plurality of correction inlays (1b, 1c, 1b ', 1c'), the individual geometric shapes being related to the geometric shape of the normal inlay (1a, 1a ') are each modified for different intraoperative corrections due to the patient-specific soft tissue situation; wherein the geometric shape of the at least one correction inlay (1b, 1c, 1b ', 1c') is a geometric shape defined by at least one of the correction inlay data sets. 4. Inlay system according to claim 1 or 2, wherein the inlay system comprises at least one adjustable inlay, wherein the adjustable inlay comprises a setting means by means of which its geometric shape can be changed continuously or stepwise, wherein different geometric shapes of different correction inlays correspond. 5. Inlay system (1a, 1b, 1c, 1a ', 1b', 1c ') according to claim 2 and one of claims 3 or 4, wherein the individual correction inlays (1b, 1c, 1b', 1c ' ) or correction inlay data sets comprise a set of correction inlays (1b, 1c, 1b ', 1c') or correction inlay data sets for correction angle graded intraoperative varus / valgus corrections and / or graded slope corrections. The inlay system (1a, 1b, 1c, 1a ', 1b', 1c ') according to claim 5, wherein the set of correction inlays (1b, 1c, 1b', 1c ') or correction inlay data sets for Varus A / Algus corrections are designed with a correction angle of up to 3 °. The inlay system (1a, 1b, 1c, 1a ', 1b', 1c ') according to claim 6, wherein the set of correction inlays (1b, 1c, 1b', 1c ') or correction inlay data sets is four Correction inlays (1b, 1c, 1b ', 1c') or four correction inlay datasets, in particular exactly four correction inlays or correction inlay datasets, and the four correction inlays (1b, 1c, 1b ', 1c ') or correction inlay data records are designed for a correction angle of 1 ° and 3 ° varus and 1 ° and 3 ° valgus, respectively. 8. Inlay system (1a, 1b, 1c, 1a ', 1b', 1c ') according to one of claims 1 to 7, wherein the tibial-side interface structure is designed for direct mounting on the tibia. The inlay system (1a, 1b, 1c) of any one of claims 1 to 7, wherein the tibial-side interface structure is adapted for mounting on a separate tibial implant (2). 10. Inlay system (1a, 1b, 1c, 1a ', 1b', 1c ') according to one of claims 1 to 9, wherein the geometric shape of the normal inlay (1a, 1a') and the at least one correction inlay (1b, 1c, 1b ', 1c') is patient-specific. 11. A system for producing a total knee prosthesis (1b, 1c, 1b ', 1c', 2, 3), comprising: a) inlay system according to claim 1; b) a femoral implant (3), wherein the femoral implant (3) comprises a femoral-side interface structure for mounting to a femur and a tibial-side interface structure opposite the femoral-side interface structure, and the tibial-side interface structure for flexible cooperation with the femoral-side interface structure of the correctional inlay (1b 1c, 1b ', 1c'). 12. A method for producing an inlay system (1a, 1b, 1c, 1a ', 1b', 1c ') for a total knee prosthesis (1b, 1c, 1b', 1c ', 2, 3), the method comprising: a) Providing a normal inlay (1a, 1a ') or a normal inlay data set defining the geometric shape of a normal inlay (1a, 1a'), the normal inlay data record being stored in a non-transitory computer-readable medium, wherein the normal inlay (1a, 1a ') has a tibial-side interface structure for mounting on a tibia and a femoral-side interface structure opposite the tibial-side interface structure for flexible cooperation with a femoral implant (3); wherein the geometric shape of the normal inlay (1a, 1a ') is determined, preferably in a preoperative operation planning, corresponding to a corrected postoperative mechanical leg axis without taking account of corrections required by a patient-specific soft-tissue situation; b) producing at least one correction inlay (1b, 1c, 1b ', 1c'), wherein a geometric shape of the at least one correction inlay (1b, 1c, 1b ', 1c') on the geometrical shape of the normal inlay ( 1a, 1a ') and the at least one correction inlay (1b, 1c, 1b', 1c ') has a tibial-side interface structure identical to the normal inlay (1a, 1a') and a femoral-side interface structure for flexible interaction with the same femoral implant (FIG. 3) as the normal inlay (1a, 1a ') comprises; wherein the geometric shape of the at least one correction inlay (1b, 1c, 1b ', 1c') is modified with respect to the normal inlay (1a, 1a ') for an intraoperative correction based on the patient-specific soft-tissue situation.