Patent Description:
During a total knee arthroplasty, tibial trial insert systems are typically used to assist a surgeon in determining a size, shape or other configuration of a permanent prosthesis that is designed to replace a portion of the knee joint. In particular, such tibial trial insert systems are used to determine a relative spacing between a femoral component and a tibial component of the permanent prosthesis.

<CIT> discloses a tibial trial insert system comprising a bearing component having a superior articulating surface and an inferior surface; a base component having a superior surface and an inferior surface, the base component configured to removably engage with the bearing component; and a plurality of shims, each shim configured to be slidable between the inferior surface of the bearing component and the superior surface of the base component to change a relative proximal/distal spacing between the bearing component and the base component.

<CIT> discloses a tibial trial insert system with a bearing component, a plate component, a spacing adjustment assembly and a plurality of shims. The bearing component has a superior articulating surface and an inferior surface. The plate component has a superior surface and an inferior fixation surface. The spacing adjustment assembly is arranged between the inferior surface of the bearing component and the superior surface of the plate component and configured to allow an adjustment of a proximal/distal spacing between the bearing component and the plate component. The proximal/distal spacing can be adjusted by sliding one of said shims between the plate component and the bearing component. The spacing adjustment assembly is formed of an elongated sheet being rolled into a coil configuration and having a first end and a second end, wherein the first end is welded to the plate component and the second end is welded to the bearing component. Multiple such coil configurations can be provided between and connected to the plate component and the bearing component at any suitable position, e.g., on a lateral and/or medial side.

It is an object of the present invention to provide an alternative tibial trial insert system.

According to one aspect, a tibial trial insert system is provided, said tibial trial insert system comprising: a bearing component having a superior articulating surface and an inferior surface; a plate component having a superior surface and an inferior fixation surface; at least a first spacing adjustment assembly and a second spacing adjustment assembly, each spacing adjustment assembly configured to be arrangeable between the inferior surface of the bearing component and the superior surface of the plate component, and each spacing adjustment assembly having at least one superior connector element configured to removably engage with the bearing component and at least one inferior base element configured to removably engage with the plate component, wherein the connector element is movably coupled to the base element in proximal/distal direction; a plurality of shims, each shim configured to be slidable between an inferior surface of the connector element and a superior surface of the base element of the first spacing adjustment assembly and/or the second spacing adjustment assembly to adjust a proximal/distal height of the respective spacing adjustment assembly, in order to thereby adjust a relative proximal/distal spacing between the bearing component and the plate component; wherein the first spacing adjustment assembly is configured to allow an adjustment of the proximal/distal spacing within a first adjustment range and the second spacing adjustment assembly is configured to allow an adjustment of the proximal/distal spacing within a second adjustment range. Owing to the solution according to the invention, in particular an improved adjustment of the proximal/distal spacing can be achieved. In particular stacking of a large number of shims one above the other to obtain a suitable distal/proximal spacing can be prevented. Such superposed stacking of a large number of shims may cause, in particular, detrimental dimensional deviations and/or reduced stability of the tibial trial insert system. In order to counteract such effects, the tibial trial insert system according to the invention includes at least two different spacing adjustment assemblies, namely at least the first spacing adjustment assembly and the second spacing adjustment assembly. The at least two spacing adjustment assemblies are exchangeable against each other during use of the tibial trial insert system. Accordingly, there are actually not both spacing adjustment assemblies disposed at the same time between the bearing component and the plate component, but either the first or the second spacing adjustment assembly. The spacing adjustment assemblies have different adjustment ranges, namely the first adjustment range and the second adjustment range. The different adjustment ranges are achieved by a different configuration of the spacing adjustment assemblies. To this end, the first spacing adjustment assembly has one or more of a size and/or dimension that differs from the respective size and/or dimension of the second spacing adjustment assembly. Preferably, the base element of the first spacing adjustment assembly has a smaller thickness than the base element of the second spacing adjustment assembly, or vice versa. As an alternative or in addition, the connector element of the first spacing adjustment assembly can have a smaller thickness than the connector element of the second spacing adjustment assembly, or vice versa. Further as an alternative or in addition, the base element and the connector element of the second spacing adjustment assembly - without additional provision of a shim - may be farther spaced from each other in the proximal direction than the base element and the connector element of the first spacing adjustment assembly. In this document, the terms "superior", "inferior", "anterior", "posterior", "medial", "lateral", "proximal" and "distal" are used according to their standard anatomical definitions. In this document the phrase "proximal/distal spacing" denotes a spacing that extends in proximal and/or distal direction. Analogously, the phrase "anterior/posterior" means anterior and/or posterior; the phrase "medial/lateral" means medial and/or lateral. The plate component can also be termed "tibial plateau component".

In one embodiment each spacing adjustment assembly is adjustable between a minimum height and a maximum height, wherein the minimum height of the second spacing adjustment assembly is equal to or greater than the maximum height of the first spacing adjustment assembly. The adjustment between the minimum height and the maximum height is obtained in each case by inserting at least one shim of the plurality of shims between the inferior surface of the respective connector element and the superior surface of the respective base element. The respective minimum height is achieved without inserting of a shim. For achieving the respective maximum height, at least one of the shims is required. Preferably, the respective maximum height is limited by a stop acting in the proximal/distal direction between the respective connector element and the respective base element. The minimum of the first adjustment range is achieved when the first adjustment assembly is adjusted to its minimum height. The maximum of the first adjustment range is achieved when the first spacing adjustment assembly is adjusted to its maximum height. The minimum of the second adjustment range is achieved when the second spatial adjustment assembly is adjusted to its minimum height. The maximum of the second adjustment range is achieved when the second spacing adjustment assembly is adjusted to its maximum height.

In one embodiment the first spacing adjustment assembly and the second spacing adjustment assembly differ with respect to a thickness of the respective base element in order to allow the adjustment within the different first and second adjustment ranges. This embodiment of the invention allows a particularly simple design adaptation and/or dimensioning of the different adjustment ranges. In simple terms, the difference in thickness of the two base elements causes an offset between the first adjustment range and the second adjustment range, which dimensionally corresponds to the difference in thickness. Preferably, the first spacing adjustment assembly and the second spacing adjustment assembly are at least largely, preferably completely, of identical design, with the exception of the different thicknesses of the base elements. As a result, in particular cost benefits may be achieved due to simplified manufacture and assembly.

In one embodiment the thickness of the base element of the second spacing adjustment assembly is at least <NUM> larger than the thickness of the base element of the first spacing adjustment assembly. The inventors have found that a difference of at least <NUM> offers particular advantages. In this way, an offset of at least <NUM> between the first adjustment range and the second adjustment range is achieved. Preferably, the difference between the thickness of the base element of the second spacing adjustment assembly and of the base element of the first spacing adjustment assembly is exactly <NUM>.

In one embodiment the plurality of shims comprises a first set of shims provided together and a second set of shims provided together, the first set of shims configured for use with the first spacing adjustment assembly and the second set of shims configured for use with the second spacing adjustment assembly. Preferably, the shims of the first set of shims are each slidable between the inferior surface of the connector element and the superior surface of the base element of the first spacing adjustment assembly, while being not slidable between the respective surfaces of the second spacing adjustment assembly. Preferably, the same holds vice versa for the shims of the second set of shims. For this purpose, at least a size, dimension or shape of the shims of the first set of shims is matched to a corresponding size, dimension and/or shape of the first spacing adjustment assembly. The same applies correspondingly in regards to the configuration of the shims of the second set of shims. The shims of the first set of shims may have an identical design. As an alternative, the shims may have a different design as to dimensions, for examples in regards to their thicknesses. The same applies again correspondingly to the shims of the second set of shims. The shims may each be used individually or in addition with further shims of the respective set in order to form a superposed stack of shims.

In one embodiment the first set of shims comprises at least a first shim having a first thickness and a second shim having a second thickness, the second thickness being twice the first thickness. The inventors have found that, owing to this embodiment of the invention, a particularly advantageous adaptation in predetermined incremental steps within the first adjustment range can be achieved. Preferably, the first thickness is between <NUM> and <NUM>, particularly preferred <NUM>.

In one embodiment the second set of shims comprises at least a third shim having a third thickness, the third thickness being twice the second thickness. The inventors have found that in this way a particularly advantageous incremental adjustment within the second adjustment range can be achieved. Preferably, the third thickness is between <NUM> and <NUM>, particularly preferred <NUM>.

In one embodiment different shims of the plurality of shims have different matching portions, wherein the different matching portions differ in size and/or shape and are thereby configured either for matching with a complementary first matching portion of the first spacing adjustment assembly or for matching with a complementary second matching portion of the second spacing adjustment assembly. The differently sized and/or shaped matching portions ensure that a respective one of the shims is usable either for adjusting the proximal/distal height of the first spacing adjustment assembly or of the second spacing adjustment assembly. The different configurations of the complementary first matching portion and the complementary second matching portion ensure that merely one of the shims provided for that purpose in intended use is insertable between the inferior surface of the respective connector element and the superior surface of the respective base element. In an inserted state for intended use, appropriately fitting matching portions interact preferably in a form-fitted manner. In contrast, not complementary matching portions preferably act as a type of stop which prevents complete insertion for intended use of the respective shim. Preferably, the complementary matching portions of the spacing adjustment assemblies are disposed on the respective connector element and/or the respective base element.

In one embodiment the matching portions are formed as concave matching surfaces and the complementary matching portions are formed as convex matching surfaces, or vice versa. This embodiment offers particular advantages in regards to simple and cost-efficient manufacture of the matching portions. Preferably, a main extension direction of the surface normal of the respective matching surface extends in anterior/posterior direction.

In one embodiment - with respect to each of the spacing adjustment assemblies - engagement of the respective connector element with the bearing component and engagement of the respective base element with the plate component restrains an anterior/posterior movement and/or a medial/lateral movement between the bearing component and the plate component. For engagement with the respective base element, the plate component preferably has a recess, into which recess a portion provided for that purpose can be accommodated in anterior/posterior direction and/or medial/lateral direction in a form-fitting manner. For engagement with the respective connector element, the bearing component preferably has an engagement portion which interacts with a complementary engagement portion of the respective connector element, thereby forming a plug-in, latching and/or snap-in connection.

The respective connector element is coupled to the respective base element to be movable in proximal, distal direction. Preferably, the movability between the respective connector element and the respective base element in the proximal direction is limited by means of a stop or the like. Further preferred, the respective base element and the respective connector element are coupled to be immobile in relation to each other in the anterior/posterior direction and/or medial/lateral direction.

In one embodiment each spacing adjustment assembly comprises at least one coupling arrangement configured to movably and captively couple the respective connector element with the respective base element. The respective connector element and the respective base element are coupled to each other to be movable relative to one another in proximal/distal direction by means of the coupling arrangement. In anterior/posterior direction and/or medial/lateral direction the coupling arrangement causes a preferably form-fitted connection between the respective connector element and the respective base element. If the respective spacing adjustment assembly includes more than one connector element, preferably, each of the connector elements is assigned a separate coupling arrangement.

In one embodiment each coupling arrangement forms a telescope mechanism which is extendable in proximal direction and retractable in distal direction. In this way, a particularly robust and easily to manufacture configuration of the coupling arrangement is achieved. The telescope mechanism is telescoping in the proximal/distal direction and, in this respect, extendable in the proximal direction and retractable in the distal direction. The respective telescope mechanism is fixed to the respective base element on one end and to the respective connector element on the other end.

In one embodiment each coupling arrangement comprises at least a first cylinder element and a second cylinder element, wherein the first cylinder element is slidably received in a bore of the base element, wherein the second cylinder element is slidably received in a bore of the first cylinder element, and wherein the second cylinder element is fixedly connected to the inferior surface of the respective connector element. Preferably, the bore of the base element and the bore of the first cylinder element are arranged coaxially. The bore of the base element and the bore of the first cylinder element extend in proximal/distal direction. This embodiment offers a furthermore simplified construction and at the same time a particularly robust and narrowly tolerated coupling between the respective connector element and the respective base element and, thus, also between the bearing component and the plate component.

The invention is defined in the claims. Any subject-matter that is disclosed herein, but which is not defined in the claims, does not form part of the invention.

In the following, an embodiment of the invention will be described in detail with reference to the drawings. The drawings schematically show:.

According to <FIG>, a tibial trial insert system <NUM> is provided for use in a knee joint replacement surgery. The tibial trial insert system <NUM> comprises a bearing component <NUM>, a plate component <NUM>, at least a first spacing adjustment assembly <NUM> and a second spacing adjustment assembly <NUM> and a plurality of shims <NUM>, <NUM>, <NUM> (<FIG>) not shown in <FIG>.

The bearing component <NUM> has a superior articulating surface <NUM>, an opposing inferior surface <NUM> and a peripheral wall <NUM> extending from the inferior surface <NUM> to the superior articulating surface <NUM>. The bearing component <NUM> further includes an anterior side <NUM>, a posterior side <NUM>, a lateral side <NUM> and a medial side <NUM>. The superior articulating surface <NUM> is configured to articulate with natural or prosthetic condyles of a distal femur and includes a lateral articulating surface portion <NUM> and a medial articulating surface portion <NUM>.

The plate component <NUM> has a superior surface <NUM>, an opposing inferior fixation surface <NUM> and a peripheral wall <NUM> extending from the inferior fixation surface <NUM> to the superior surface <NUM>. The plate component <NUM> further includes an anterior side <NUM>, a posterior side <NUM>, a lateral side <NUM> and a medial side <NUM>. The inferior fixation surface is configured for direct or indirect fastening to a proximal end of a tibia.

The first spacing adjustment assembly <NUM> is configured to be arrangable between the inferior surface <NUM> of the bearing component <NUM> and the superior surface <NUM> of the plate component <NUM>. The first spacing adjustment assembly <NUM> comprises at least one superior connector element <NUM> configured to removably engage with the bearing component <NUM> and at least one inferior base element <NUM> configured to removably engage with the plate component <NUM>, wherein the connector element <NUM> is coupled to the base element <NUM> to be movable in proximal/distal direction.

The second spacing adjustment assembly <NUM> is configured to be arrangable between the inferior surface <NUM> of the bearing component <NUM> and the superior surface <NUM> of the plate component <NUM>. The second spacing adjustment assembly <NUM> comprises at least one superior connector element <NUM> configured to removably engage with the bearing component <NUM> and at least one inferior base element <NUM> configured to removably engage with the plate component <NUM>, wherein the connector element <NUM> is coupled to the base element <NUM> to be movable in proximal/distal direction.

The first spacing adjustment assembly <NUM> and the second spacing adjustment assembly <NUM> are intended for adjusting a relative proximal/distal spacing between the bearing component <NUM> and the plate component <NUM>. In other words, both spacing adjustment assemblies <NUM>, <NUM> are intended to position the superior articulating surface <NUM> and/or the bearing component <NUM> in different height levels relative to the plate component <NUM>, in particular relative to the inferior fixation surface <NUM> of the plate component <NUM>. Such a spacing or height adjustment is required for trial reposition in knee joint replacement surgery. Said trial reposition is a preceding operation step of the actual knee joint replacement, wherein sizes, dimensions and/or shapes of the tibial and femoral implant components required for a functional replacement of the knee joint are determined. This application related background of the tibial trial insert system <NUM> is well-known to a person skilled in the art. Therefore, no further explanations are needed in that respect.

With respect to said height and/or spacing adjustment, each shim <NUM>, <NUM>, <NUM> (<FIG>) of said plurality of shims is configured to be slidable between an inferior surface <NUM>, <NUM> of the at least one connector element <NUM>, <NUM> and a superior surface <NUM>, <NUM> of the at least one base element <NUM>, <NUM> of the first spacing adjustment assembly <NUM> and/or the second spacing adjustment assembly <NUM> to adjust the proximal/distal height of the respective spacing adjustment assembly <NUM>, <NUM>, in order to thereby adjust the relative proximal/distal spacing between the bearing component <NUM> and the plate component <NUM>.

For that purpose, a single shim or a plurality of superposed stacked shims can be inserted between the inferior surface <NUM>, <NUM> and the superior surface <NUM>, <NUM>, also one after the other, as required.

The first spacing adjustment assembly <NUM> is configured to allow an adjustment of the proximal/distal spacing within a first adjustment range and the second spacing adjustment assembly <NUM> is configured to allow an adjustment of the proximal/distal spacing within a second adjustment range. For adjusting the proximal/distal spacing within the first adjustment range, the operating surgeon selects the first spacing adjustment assembly <NUM>, places the latter between the bearing component <NUM> and the plate component <NUM>, and connects the at least one connector element <NUM> and the base element <NUM> to the bearing component <NUM> and the plate component <NUM>, respectively, in a manner described in more detail below. For adjusting the proximal, distal spacing within the first adjustment range, the operating surgeon can insert at least one of the shims <NUM>, <NUM>, <NUM> between the inferior surface <NUM> and the superior surface <NUM>. For adapting the proximal/distal spacing within the second adjustment range, the operating surgeon selects the second spacing adjustment assembly <NUM>, places the latter between the bearing component <NUM> and the plate component, and connects the at least one connector element <NUM> and the base element <NUM> to the bearing component <NUM> and the plate component <NUM>, respectively, in a manner described in more detail below. For adapting the proximal/distal spacing within the second adjustment range, the operating surgeon can insert at least one of the shims <NUM>, <NUM>, <NUM> between the inferior surface <NUM> and the superior surface <NUM>.

In the embodiment as illustrated, the first spacing adjustment assembly <NUM> includes two superior connector elements <NUM>, <NUM>. Said elements may also be referred to as lateral connector element <NUM> and medial connector element <NUM>. The same applies correspondingly to the configuration of the second spacing adjustment assembly <NUM> (<FIG>). Such a configuration having a medial connector element <NUM>, <NUM> and a lateral connector element <NUM>, <NUM> is advantageous, but not mandatory. Accordingly, in an embodiment not illustrated in the drawings, merely one superior connector element is provided.

The physical configuration and operative functionality of the first spacing adjustment assembly <NUM> and the second spacing adjustment assembly <NUM> are most largely - but not completely - identical. To avoid repetitions, predominantly the configuration and operative functionality of the first spacing adjustment assembly <NUM> will be discussed below. The same applies correspondingly in regards to the second spacing adjustment assembly <NUM>, unless otherwise described.

The base element <NUM> has an inferior surface <NUM> disposed opposite the superior surface <NUM>. Moreover, the base element <NUM> has a peripheral wall <NUM> extending between the inferior surface <NUM> and the superior surface <NUM>, and an anterior side <NUM>, a posterior side <NUM>, a lateral side <NUM> and a medial side <NUM>. The peripheral wall <NUM> has an outer contour A. For removable engagement with the base element <NUM>, the plate component <NUM> has a receiving recess <NUM> which is countersunk in the distal direction into the superior surface <NUM>. The receiving recess <NUM> has and an inner contour A' which is complementary to the outer contour A. In a condition received in the receiving recess <NUM>, the base element <NUM> is restrained in the anterior/posterior direction and lateral/medial direction.

For movable coupling of the lateral connector element <NUM> to the base element <NUM>, the first spacing adjustment assembly <NUM> includes a coupling arrangement <NUM>. The coupling arrangement <NUM> is configured to movably and captively couple the medial connector element <NUM> with the base element <NUM>. The coupling arrangement <NUM> forms a telescope mechanism which is extendable in proximal direction and retractable in distal direction.

In the embodiment as illustrated, the coupling arrangement <NUM> comprises at least a first cylinder element <NUM> and a second cylinder element <NUM>. The first cylinder element <NUM> is slidably received in a bore <NUM> of the base element <NUM>, the second cylinder element <NUM> is slidably received in a bore <NUM> of the first cylinder element <NUM>, and the second cylinder element <NUM> is fixedly connected to the inferior surface <NUM> of the medial connector element <NUM> (<FIG>).

The bores <NUM>, <NUM> extend coaxially in the proximal/distal direction and are configured as through bores. The bore <NUM> is provided with radial guiding slots <NUM> which are produced in a proximal end wall <NUM>. The first cylinder element <NUM> comprises guiding ridges (not specified in more detail) projecting in the radial direction which interact in the peripheral direction with the guiding slots <NUM> in a form-fitting manner. In this way, any unintentional turning of the first cylinder element <NUM> in the bore <NUM> is inhibited. The proximal end wall <NUM> acts as a stop and limits displaceability of the first cylinder element <NUM> in the proximal direction relative to the base element <NUM>. In that context, the proximal end wall <NUM> interacts with a distal radial collar <NUM> of the first cylinder element <NUM>.

In accordance with the first cylinder element <NUM>, the second cylinder element <NUM> comprises a distal radial collar <NUM> and two guiding ridges <NUM> projecting diametrically in the radial direction. The radial collar <NUM> interacts with a proximal end wall <NUM> of the first cylinder element <NUM> for limiting the proximal displaceability of the second cylinder element <NUM> relative to the first cylinder element <NUM>.

The proximal end of the second cylinder element <NUM> is fixedly joined to the inferior surface <NUM> of the medial connector element <NUM>. In the embodiment as shown, a welded connection is provided for that purpose between a pin element <NUM> towering from the inferior surface <NUM> in the distal direction, and a pin hole inserted into the proximal end of the second cylinder element <NUM> in the distal direction, which pin hole is not visible in more detail. As a result, the medial connector element <NUM> is capable of guided displacement relative to the base element <NUM> in a limited manner in proximal/distal direction.

The coupling arrangement <NUM> may also be referred to as medial coupling arrangement. For coupling of the medial connector element <NUM> with limited movability, accordingly a medial coupling arrangement <NUM>' is provided (<FIG>). The configuration and operative functionality of the medial coupling arrangement <NUM>' are identical to the configuration and operative functionality of the lateral coupling arrangement <NUM>. The disclosure given in relation to the lateral coupling arrangement <NUM> applies correspondingly also in regards to the medial coupling arrangement <NUM>'.

For removable engagement with the lateral connector element <NUM>, the bearing component <NUM> comprises an engagement portion <NUM>. The engagement portion <NUM> is countersunk into the inferior surface <NUM> of the bearing component <NUM> in the proximal direction. In the embodiment as illustrated, the engagement portion <NUM> is designed in the form of a dove tail guide. The latter is plug-in connectable to the lateral connector element <NUM> in anterior/posterior direction. In the plugged-together state, relative movement between the lateral connector element <NUM> and the bearing component <NUM> is inhibited, in any case in proximal/distal direction and in medial/lateral direction. Moreover, the bearing component <NUM> comprises a further engagement portion <NUM>' which is provided for removable engagement with the medial connector element <NUM> and is designed in correspondence to the engagement portion <NUM>.

The second spacing adjustment assembly <NUM>, illustrated in particular with reference to <FIG>, is most largely identical to the first spacing adjustment assembly <NUM>, as discussed before, wherein in particular a lateral coupling arrangement <NUM> and a medial coupling arrangement <NUM>' are provided. To avoid repetitions, components and/or portions of the second spacing adjustment assembly <NUM> which are identical to those of the first spacing adjustment assembly <NUM> will not be explained specifically. In particular with reference to <FIG>, said components and/or portions are marked with reference numerals which are in accordance with corresponding reference numerals of the first spacing adjustment assembly <NUM> as to their respective second and third digits.

The essential difference between the first and second spacing adjustment assemblies <NUM>, <NUM> is in a configuration of the respective base element <NUM> and <NUM>, differing in thickness. The base element <NUM> of the first spacing adjustment assembly <NUM> has a thickness T1. The base element <NUM> of the second spacing adjustment assembly <NUM> has a thickness T2.

In the embodiment as illustrated, the thickness T1 is defined as the distance between the inferior surface <NUM> and the superior surface <NUM> in proximal/distal direction. The same applies correspondingly in regards to the definition of the thickness T2 of the base element <NUM>. Of course, definitions of thickness deviating therefrom are also conceivable. For example, the thickness can be defined as a proximal/distal spacing between the respective inferior surface and a proximal upper edge of the bores <NUM>, <NUM>' and <NUM>, <NUM>', respectively.

The thickness T1 may also be referred to as first thickness. The thickness T2 may also be referred to as second thickness. In the embodiment as illustrated, the difference between the first thickness T1 and the second thickness T2 is essential for said difference between the first adjustment range and the second adjustment range.

In the configurations illustrated with reference to <FIG>, the connector elements <NUM>, <NUM>, <NUM>, <NUM> are displaced in the proximal direction relative to the respective base element <NUM>, <NUM>. In that context, the first spacing adjustment assembly <NUM> assumes a maximum height H2. The merely schematically illustrated minimum height H1 is reached when both the connector elements <NUM>, <NUM> are each displaced to a maximum in the distal direction. In such a condition, the inferior surfaces of the connector elements <NUM>, <NUM> each rest flat on the base element <NUM>. The second spacing adjustment assembly <NUM> is correspondingly adjustable between a minimum height H3 and a maximum height H4. In the embodiment as illustrated, the maximum height H2 of the first spacing adjustment assembly <NUM> is equal to the minimum height H3 of the second spacing adjustment assembly <NUM>.

For adjusting the height of the two spacing adjustment assemblies <NUM>, <NUM>, the tibial trial insert system <NUM> comprises a plurality of shims, three shims <NUM>, <NUM>, <NUM> of the plurality of shims being illustrated as an example with reference to <FIG>. The dots in <FIG> symbolize that the plurality of shims can comprise further shims in addition to the shims <NUM>, <NUM>, <NUM> expressively depicted in <FIG>. The shims depicted therein can also be referred to as first shim <NUM>, second shim <NUM>, and third shim <NUM>. The plurality of shims comprises at least one first shim <NUM>, one second shim <NUM> and one third shim <NUM>. Preferably, the plurality of shims comprises several first shims, several second shims and several third shims.

In the embodiment as illustrated, the first shim <NUM> and the second shim <NUM> are provided exclusively for adjusting the height of the first spacing adjustment assembly <NUM>. The third shim <NUM> is provided exclusively for adjusting the height of the second spacing adjustment assembly <NUM>.

In order to prevent any not intended assignment of the second shim <NUM> to the second spacing adjustment assembly <NUM>, the second shim <NUM> includes at least one matching portion <NUM> which is configured for matched fitting with a complementary first matching portion <NUM> of the base element <NUM> (<FIG>). In a completely inserted state of the second shim <NUM>, the matching portion <NUM> rests on the complementary first matching portion <NUM>, contacting across the surface.

The third shim <NUM> includes at least one matching portion <NUM> of different shape, which can be fitted matching with a complementary second matching portion <NUM> of the base element <NUM> of the second spacing adjustment assembly <NUM>. Thereby, the different configuration and/or shape of the matching portions <NUM>, <NUM> of the two shims <NUM>, <NUM> prevent any not intended use of the shims.

The matching portions <NUM>, <NUM> are each in the form of a concave matching surface <NUM> and <NUM>, respectively. The complementary first matching portion <NUM> is accordingly in the form of a convex matching surface <NUM>. The same applies correspondingly to the design of the complementary second matching portion <NUM> in the form of a convex matching surface <NUM>.

In the embodiment as illustrated, the complementary first matching portion <NUM> is a radially oriented outer circumference which towers from the superior surface <NUM> in the proximal direction and surrounds the bore <NUM> concentrically. The same applies correspondingly in regards to the complementary second matching portion <NUM>. In that context, as compared to the complementary first matching portion <NUM>, the complementary second matching portion <NUM> has radial bulge (not specified in more detail) which is shaped complementary to a depression of the matching portion <NUM> or the concave matching surface <NUM> of the third shim <NUM> (not specified in more detail).

In the embodiment as illustrated, the second shim <NUM> comprises a further matching portion <NUM>' which is configured as a further concave matching surface <NUM>'. In this respect, it may also be referred to as medial and lateral matching portions <NUM>, <NUM>'. Accordingly, also the base element <NUM> comprises a further first matching portion <NUM>' which is configured as a further convex matching surface <NUM>'. The same applies correspondingly in regards to the configuration of the third shim <NUM> and the base element <NUM>.

As illustrated in particular with reference to <FIG>, the shims <NUM>, <NUM>, <NUM> have different thicknesses t1, t2, t3 in the proximal/distal direction. The first shim <NUM> has a first thickness t1. The second shim <NUM> has a second thickness t2. The third shim <NUM> has a third thickness t3.

In the embodiment as illustrated, the second thickness t2 is twice the first thickness t1. The third thickness t3 is twice the second thickness t2. In the present case, <NUM> is provided as the first thickness t1. The second thickness t2 and the third thickness t3 are accordingly <NUM> and <NUM>, respectively.

In the embodiment as illustrated, the difference between the thickness t2 of the base element <NUM> and the thickness t1 of the base element <NUM> is <NUM>.

With reference to <FIG>, different configurations of the tibial trial insert system <NUM> are shown in different sectional views and in different height level adjustment situations.

The <FIG> show the tibial trial insert system <NUM> in a first configuration for adjusting the proximal/distal spacing within the first adjustment range. For that purpose, the first spacing adjustment assembly <NUM> is disposed between the bearing component <NUM> and the plate component <NUM>, in the above described manner. In a first adjustment situation (<FIG>), the first spacing adjustment assembly <NUM> assumes its minimum height H1. Thereby, the articulating surface <NUM> is spaced <NUM> from the inferior fixation surface <NUM>. In the present case, there is no shim needed to produce this adjustment situation.

In an exemplary second adjustment situation (<FIG>), the articulating surface <NUM> is located <NUM> above the inferior fixation surface <NUM>. Said adjustment is produced by inserting a total of four superposed stacked second shims <NUM>. In this case, the first spacing adjustment assembly <NUM> assumes its maximum height H2.

It is evident that further adjustment situations are possible with said first configuration of the tibial trial insert system <NUM>. In the present case, the proximal/distal spacing is adjustable to <NUM> (<FIG>), <NUM>, <NUM>, <NUM>, <NUM> and <NUM> (<FIG>) are provided. For adjustment to <NUM>, a first shim <NUM> is inserted, in the present case. For adjustment to <NUM>, a second shim <NUM> is inserted instead. For adjustment to <NUM>, <NUM> or <NUM>, there are two, three or four second shims inserted as a superposed stack.

For adjusting the first spacing adjustment assembly <NUM> within the first adjustment range to the above described discrete proximal/distal spacings, the tibial trial insert system <NUM> comprises a first set of shims (not expressively illustrated in the drawings in more detail). The first set of shims is provided together and consists of four second shims <NUM> and one first shim <NUM>.

With reference to <FIG>, a second configuration of the tibial trial insert system <NUM> is shown which allows adjusting of the proximal/distal spacing within the second adjustment range. For that purpose, instead of the first spacing adjustment assembly <NUM>, the second spacing adjustment assembly <NUM> is disposed between the bearing component <NUM> and the plate component <NUM>. In the embodiment as illustrated, said second configuration allows for three adjustment situations. In the first adjustment situation (<FIG>), the second spacing adjustment assembly <NUM> assumes its minimum height H3. Said height corresponds to the maximum height H2 of the first spacing adjustment assembly <NUM>. Accordingly, the superior articulating surface <NUM> is <NUM> spaced from the inferior fixation surface <NUM>. For producing said first adjustment situation of the second configuration, there is no shim needed.

In a second adjustment situation (<FIG>), a third shim <NUM> is inserted. As a result, a comparatively greater proximal/distal height of the second spacing adjustment assembly <NUM> and, thus, also a greater proximal/distal spacing is obtained. The height and the spacing, respectively, are increased by the thickness t3 of the third shim <NUM> such that a proximal/distal spacing of <NUM> is obtained.

In a third adjustment situation (<FIG>), the second spacing adjustment assembly <NUM> assumes its maximum height H4. For that purpose, two third shims are inserted such that a proximal/distal spacing of <NUM> is obtained in the present case.

Claim 1:
Tibial trial insert system (<NUM>), comprising:
- a bearing component (<NUM>) having a superior articulating surface (<NUM>) and an inferior surface (<NUM>);
- a plate component (<NUM>) having a superior surface (<NUM>) and an inferior fixation surface (<NUM>);
- at least a first spacing adjustment assembly (<NUM>) and a second spacing adjustment assembly (<NUM>),
- each spacing adjustment assembly (<NUM>, <NUM>) configured to be arrangeable between the inferior surface (<NUM>) of the bearing component (<NUM>) and the superior surface (<NUM>) of the plate component (<NUM>), and
- each spacing adjustment assembly (<NUM>, <NUM>) having at least one superior connector element (<NUM>, <NUM>, <NUM>, <NUM>) configured to removably engage with the bearing component (<NUM>) and at least one inferior base element (<NUM>, <NUM>) configured to removably engage with the plate component (<NUM>), thereby allowing to exchange the first spacing adjustment assembly (<NUM>) against and the second spacing adjustment assembly (<NUM>) and vice versa, wherein the connector element (<NUM>, <NUM>, <NUM>, <NUM>) is movably coupled to the base element (<NUM>, <NUM>) in proximal/distal direction;
- a plurality of shims (<NUM>, <NUM>, <NUM>), each shim configured to be slidable between an inferior surface (<NUM>, <NUM>) of the connector element (<NUM>, <NUM>, <NUM>, <NUM>) and a superior surface (<NUM>, <NUM>) of the base element (<NUM>, <NUM>) of the first spacing adjustment assembly (<NUM>) and/or the second spacing adjustment assembly (<NUM>) to adjust a proximal/distal height of the respective spacing adjustment assembly (<NUM>, <NUM>), in order to thereby adjust a relative proximal/distal spacing between the bearing component (<NUM>) and the plate component (<NUM>);
- wherein the first spacing adjustment assembly (<NUM>) is configured to allow an adjustment of the proximal/distal spacing within a first adjustment range and the second spacing adjustment assembly (<NUM>) is configured to allow an adjustment of the proximal/distal spacing within a second adjustment range.