Tibial sample implant with gearing mechanism

Abstract

The invention relates to a tibial sample implant (1, 100) for use in knee joint replacement surgery, having a lower part (2, 102) which is provided for a tibial fixation, an upper part (3, 103) which is arranged above the lower part in the vertical direction and which comprises a sliding surface (5, 105) that is arranged on the upper face of the upper part and is designed to interact with a femoral component in a sliding manner, and a height adjustment mechanism (E, E') that interacts with the upper part and lower part and can be used to move the upper part in the vertical direction (Z) in a guided manner relative to the lower part between a first setting position, in which the sliding surface is positioned at a first height (H1) above the lower part, and a second setting position, in which the sliding surface is positioned at a second height (H2) above the lower part. According to the invention, the height adjustment mechanism has a cam mechanism with at least one drive gear (6a, 6b, 106a, 106b), which is rotatably mounted on the lower part about a first rotational axis (8a, 8b) oriented parallel to the vertical direction and has a control cam (9a, 9b, 109a, 109b) that ascends in the vertical direction, and at least one output element (7a, 7b, 107a, 107b), which is rotationally fixed to the upper part and has a support section (10a, 10b, 110a, 110b) that is supported on the control cam in a sliding manner, whereby the upper part can be moved between the first setting position and the second setting position by a rotational movement of the drive gear.

Description

10

[0020] In another embodiment of the invention, the at least one drive wheel is coupled so as to transmit movement to at least one display wheel which is rotationally movably mounted on the lower part, the display wheel comprising a scale which allows reading of 15 the adjustment position of the upper part and / or of the height of the glide face. The movement transmission between the drive wheel and the display wheel may be continuous   or   intermittent.   For the movement transmission, the display wheel may be meshed with the 20 drive wheel or coupled in another way, for example by means of a catch element. Preferably, the display wheel is arranged on an outer circumference of the lower part and / or offset outward in the radial direction relative to the at least one drive wheel. The scale preferably 25 comprises a sequence of graduation lines and / or numbers. The scale is preferably arranged on an outer circumference of the display wheel.

[0021] In another embodiment of the invention, there is at least one catch element connected fixed in rotation 30 to the drive wheel, which intermittently interacts with the display wheel so that a continuous rotational movement of the drive wheel causes a stepwise rotational movement of the display wheel. The stepwise rotational movement of the display wheel which is caused in this way 35 leads to a stepwise display of the respectively reached 2021306851   01 Sep 2026 adjustment positions of the upper part. Intermediate positions, on the other hand, are not displayed. The catch element may be formed integrally on the drive wheel or configured as a component part which is manufactured 5 separately and subsequently connected to the drive wheel. The catch element interacts intermittently with a section of the display wheel which is intended therefor.

[0022] In another embodiment of the invention, there is a latch device which comprises a latch element actively 10 connected fixed in rotation to the at least one drive wheel and a complementary latch counter-element arranged on the lower part, the latch element and the latch counter-element interacting in defined rotational settings of the at least one drive wheel while forming 15 an overridable latch connection. The defined rotational settings of the at least one drive wheel correspond to adjustment positions of the upper part which are predetermined and / or are to be reached. In this way, a user receives direct tactile and / or acoustic feedback as 20 soon as said rotational setting and / or adjustment position is reached. This feedback is given by the latching of the latch device. The latch connection between the latch element and the complementary latch counter-element is overridable, so that a further 25 rotational movement of the drive wheel is also possible after reaching the defined rotational setting. In this case, the override - that is to say the release of the previously established latch connection - is associated with new tactile and / or acoustic feedback for the user. 30

[0023] In another embodiment of the invention, there is a handle releasably connectable to the lower part, having actuation mechanics, the actuation mechanics comprising an actuation wheel which is actively connected to the at least one drive wheel in a state of the handle connected 35 to the lower part. The handle allows ergonomic actuation 2021306851   01 Sep 2026 of the height adjustment mechanism. For this purpose, the actuation mechanics of the handle precede the height adjustment mechanism, or more precisely its at least one drive wheel. Manual actuation of the actuation mechanics 5 causes a rotational movement of the at least one drive wheel and therefore a corresponding change in the adjustment position of the upper part. Furthermore, the handle allows secure and ergonomic handling of the lower part. For this purpose, the handle can be connected 10 releasably to the lower part. Preferably, for this purpose, between the handle and the lower part there is a releasable latch, snap, clamp and / or plug connection which comprises at least one connecting element assigned to the handle and a connecting counter-element 15 complementary thereto on the lower part. The actuation wheel of the actuation mechanics is - in the state of the handle connected to the lower part - actively connected releasably to the at least one drive wheel. Preferably, the actuation wheel and the at least one drive wheel are 20 for this purpose meshed at least indirectly with one another. A transmission ratio between the rotational movement of the actuation wheel and the rotational movement of the at least one drive wheel may be influenced straightforwardly by means of a corresponding 25 configuration of the actuation mechanics. Depending on the selected transmission ratio, particularly precise and smooth or particularly rapid adjustment of the height adjustment mechanism may be achieved.

[0024] In another embodiment of the invention, the 30 handle comprises at least one connecting element arranged at its distal end, which is releasably connected to a complementary connecting element of the lower part in order to connect the handle to the lower part. This embodiment allows a particularly simple and robust 35 structure. Preferably, the connecting elements are configured as a latch element and a latch counter- 2021306851   01 Sep 2026 element. Alternatively, a plug or clamp connection with correspondingly configured connecting elements may be envisioned. When establishing and releasing the latch connection, the latch element and / or the complementary 5 latch counter-element are resiliently deformed. Preferably, there are at least two latch elements and complementary latch counter-elements arranged spaced apart from one another in the transverse direction. The handle extends longitudinally between the distal end and 10 its proximal end. Preferably, the actuation wheel of the actuation mechanics is arranged distally.

[0025] Further advantages and features of the invention may be found, by way of non-limiting example, from the claims and the following description of preferred 15 exemplary embodiments of the invention, which are represented with the aid of the drawings.

[0026] Fig. 1 shows a perspective view of an embodiment of a tibial trial implant according to the invention,

[0027] Fig. 2 shows the tibial trial implant according 20 to Fig. 1 in an exploded perspective view,

[0028] Fig. 3 shows a further exploded perspective view,

[0029] Fig. 4 shows the tibial trial implant according to Fig. 1 to 3 in schematic sectional representation along a section A-A according to Fig. 5, 25

[0030] Fig. 5 shows a schematic front view of the tibial trial implant according to Fig. 1 to 4,

[0031] Fig. 6 shows a further perspective view with graphical omission of individual components and / or sections of the tibial trial implant, 2021306851   01 Sep 2026

[0032] Fig. 7 shows a perspective detail view of two drive wheels of a height adjustment mechanism of the tibial trial implant according to Fig. 1 to 6,

[0033] Fig. 8 shows a further perspective view similar 5 to the representation according to Fig. 6 in a viewing direction directed obliquely upward,

[0034] Fig. 9 shows a view corresponding to Fig. 8 with additional graphical omission of the drive wheels,

[0035] Fig. 10 shows a perspective view of a further 10 embodiment of a tibial trial implant according to the invention together with a tibial trial plateau and in a first adjustment position,

[0036] Fig. 11 shows the tibial trial implant according to Fig. 10 in a second adjustment position, 15

[0037] Fig. 12 shows an exploded perspective view of the tibial trial implant according to Fig. 10 and 11,

[0038] Fig. 13 shows a perspective view of an upper part of the tibial trial implant according to Fig. 10 to 12 with a viewing direction onto a lower side, on which 20 driven elements of a height adjustment mechanism are arranged,

[0039] Fig. 14 shows a perspective view of a lower part of the tibial trial implant according to Fig. 10 to 12,

[0040] Fig.    15    shows    a    further   perspective 25 representation of the lower part in a partially exploded view, 2021306851   01 Sep 2026

[0041] Fig. 16 shows a further view of the lower part with a viewing direction onto individual components and / or sections of the height adjustment mechanism,

[0042] Fig. 17 shows a perspective view of a handle of 5 the tibial trial implant according to Fig. 10 to 12, which can be connected releasably to its lower part and comprises actuation mechanics for actuating the height adjustment mechanism, and

[0043] Fig. 18 shows a perspective detail representation 10 of a distal end of the handle according to Fig. 17.

[0044] According to Fig. 1 to 3, a tibial trial implant 1 for use in a knee joint replacement operation is provided. The tibial trial implant 1 is often referred to in medical terminology as a “trial glide face”. 15

[0045] The tibial trial implant 1 comprises a lower part 2, an upper part 3 and a height adjustment mechanism E.

[0046] The lower part 2 is provided for the tibial fixation. This means that when the tibial trial implant 1 20 is being used, the lower part 2 is arranged and fastened indirectly or directly on a proximal end of a tibia. In the embodiment shown, indirect fixation of the lower part 2 is provided, in which a lower side 4 of the lower part 2 interacts with a so-called tibial trial plateau, 25 which may be screwed to or cemented into the proximal end of the tibia.

[0047] In the embodiment shown, the lower part 2 comprises a plate-like basic shape. Accordingly, the lower part 2 respectively extends further along a 30 longitudinal direction X and a transverse direction Y compared with in a height direction Z. 2021306851   01 Sep 2026

[0048] In the present case, the lower part 2 has a two-shell configuration with an upper shell 2a and a lower shell 2b, which is advantageous in a manner described in more detail below but is not absolutely necessary. The 5 lower shell 2b is arranged below the upper shell 2a in relation to the height direction Z. The lower shell 2b comprises the lower side 4. In an assembled state, the upper shell 2a and the lower shell 2b form a reception space (not denoted in detail) for component parts and / or 10 sections described in more detail below, in particular of the height adjustment mechanism E. In the mounted state ready for use (Fig. 1), the upper shell 2a and the lower shell 2b are joined together with a force, form and / or material fit in a manner known to the person 15 skilled in the art. For example, the upper shell 2a and the lower shell 2b may be screwed, adhesively bonded, welded and / or latched to one another.

[0049] The upper part 3 is arranged above the lower part 2 in the height direction Z and comprises a glide 20 face 5 arranged on the upper side. In the embodiment shown, the glide face 5 is formed by two partial glide faces 5a, 5b, which are spaced apart from one another in the transverse direction Y by an upper-side opening (not denoted in detail) on the upper part 3. The glide face 5 25 is provided for gliding interaction with a femoral component. This femoral component may be formed by a distal end of a femur or a femoral trial implant, which is fixed thereon and has a correspondingly configured glide face. The shaping of the glide face 5 which may be 30 seen with the aid of the figures is modeled in a manner known to the person skilled in the art on the tibial articular face of a femorotibial joint.

[0050] In the embodiment shown, the glide face 5 is formed directly on the upper part 3 and to this extent 35 constitutes its upper side. Such a configuration is 2021306851   01 Sep 2026 advantageous but is not to be regarded as compulsory in respect of the present invention. In one embodiment (not shown), the glide face is arranged on a component manufactured separately from the upper part and is firmly 5 connected to the upper part in a state ready for use.

[0051] The height adjustment mechanism E is used to adjust an overall height, extending in the height direction Z, of the tibial trial implant 1. In other words, the upper part 3 and therefore the glide face 5 10 are positioned at different heights above the lower part 2 by means of the height adjustment mechanism E. Such a height adjustment of the glide face 5 is necessary during the knee joint replacement operation for so-called trial repositioning. Trial repositioning is an operation 15 step which precedes the actual knee joint replacement, during which the dimensions and shapes, required for correctly functional replacement of the knee joint, of the tibial and femoral implant components are determined. This use-related background of the tibial trial implant 20   1 is known to the person skilled in the art. No further explanations are therefore required in this regard.

[0052] The height adjustment mechanism E is actively connected in a manner described in more detail below to the upper part 3 and the lower part 2, and allows relative 25 displacement of the upper part 3 in relation to the lower part 2 along the height direction Z. The upper part 3 can thereby be displaced between different adjustment positions in the height direction H, a first adjustment position in which the glide face 5 is positioned at a 30 first height H1 (Fig. 5) above the lower part 2 being shown by way of example with the aid of Fig. 1 and 5. The first height H1 is indicated by way of example with the aid of Fig. 5 between an upper edge of the glide face 5 and the lower side 4 of the lower part 2. In a second 35 adjustment position (not graphically represented), the 2021306851   01 Sep 2026 upper part 3 is displaced upward in the height direction Z, the glide face 5 being positioned at a second height H2. The second height H2 is schematically indicated in Fig. 5. 5

[0053] The height adjustment mechanism E comprises a drive wheel 6a and a driven element 7a (cf. Fig. 6 to 9). The drive wheel 6a is mounted rotatably on the lower part 2 about a first rotation axis 8a oriented parallel to the height direction Z. The drive wheel 6a furthermore 10 comprises a control cam 9a rising in the height direction Z. The driven element 7a is firmly connected to the upper part 3 and comprises a supporting section 10a glidingly supported on the control cam 9a. The drive wheel 6a, its control cam 9a, the driven 15 element 7a and its supporting section 10a form a cam gear. The cam gear makes it possible to transmit rotational movement of the drive wheel 6a about the first rotation axis 8a into a translational movement of the upper part 3 along the height direction Z. In other words, 20 the supporting section 10a glidingly supported on the control cam 9a is pressed upward in the height direction Z during a rotation of the drive wheel 6a. In this way, the upper part 3 can be displaced for the above-described purpose between the first adjustment position and the 25 second adjustment position and the glide face 5 can therefore be positioned between the first height H1 and the second height H2 (Fig. 5). According to terminology which is moreover conventional in the field of gear technology, the drive wheel 6a and the driven element 7a 30 may also be referred to respectively by the terms “cam carrier” and “take-off member”.

[0054] In the embodiment shown, the drive wheel 6a is preceded, in a manner described in more detail below, by further component parts and / or sections of the height 35 adjustment mechanism E, which are used for manual and / or 2021306851   01 Sep 2026 tool-driven actuation. Such a configuration is not, however, compulsory. In one embodiment (not shown), the drive wheel itself may be configured for manual actuation and may for this purpose comprise a corresponding 5 actuation section, for example on an outer circumference.

[0055] Furthermore, a configuration of the tibial trial implant 1 which is at least substantially, preferably fully, mirror-symmetrical with respect to a mid-length plane X-Z is provided in the embodiment shown. 10 Accordingly, the height adjustment mechanism E is also configured correspondingly mirror-symmetrically with respect to the vertical mid-length plane X-Z. As is shown with the aid of the figures, the height adjustment mechanism E comprises two drive wheels 6a, 6b and two 15 driven elements 7a, 7b. The further drive wheel 6a and the further driven element 7a are arranged spaced apart from the drive wheel 6a and the driven element 7a in the transverse direction Y. The further drive wheel 6b is mounted rotatably on the lower part 2 about a further 20 first rotation axis 8b. The further first rotation axis 8b is oriented parallel to the first rotation axis 8a. The shaping and / or configuration of the further drive wheel 6b and of the further driven element 7a are mirror-symmetrical with the drive wheel 6a and the driven 25 element 7a with respect to the mid-length plane X-Z.

[0056] It is explicitly pointed out that the mirror-symmetrical configuration of the present embodiment is advantageous but is not to be regarded as compulsory in respect of the present invention. Accordingly, in one 30 embodiment (not shown), only one drive wheel is provided, which interacts with a driven element.

[0057] In order to avoid repetition, reference will primarily be made in detail to the drive wheel 6a and the driven element 7a in the description below. The 2021306851   01 Sep 2026 functional and physical features disclosed in this regard apply, mutatis mutandis, also in respect of the further drive wheel 6b and the further driven element 7b. This also applies vice versa. 5

[0058] The control cam 9a is formed in the present case by a control face 11a, which may also be referred to as an oblique face, helically extending with a constant pitch coaxially around the first rotation axis 8a.

[0059] The control cam 9a and therefore also the control 10 face 11a in the present case comprise disjunct subsections, namely a first control cam section 91a and a second control cam section 92a, and respectively a first control face section 1110 and a second control face section 1120. Such a configuration is not, however, 15 compulsory. In one embodiment (not shown), the control cam may be formed by a control face which is integrally continuous along its longitudinal extent.

[0060] In principle, the supporting section 10a may be supported on the supporting face 11a pointwise, linearly 20 and / or over a surface. In the present case, support over a surface is provided, so that the supporting section 11a is correspondingly formed by a supporting face 12a. The supporting face 12a is configured complementarily to the control face 11a. The supporting face 12a accordingly 25 extends helically with a constant pitch coaxially around the first rotation axis 8a. Furthermore, a disjunct configuration with two supporting face sections 1210, 1220 is provided.

[0061] The driven element 7a in the present case 30 projects downward from a lower side 13 of the upper part 3 along the height direction Z. In this case, the driven element 7a has a pin-like basic shape. The driven element 7a is formed integrally onto the lower side 13 of the 2021306851   01 Sep 2026 upper part 3. In a further embodiment, the drive element may moreover be manufactured separately from the upper part and joined in a manner known per se onto the upper part. 5

[0062] In order to allow the simplest possible replacement of the upper part 3 with a differently configured upper part, which for example comprises a differently configured glide face, in the present case a plug connection is provided between the upper part 3 and 10 the lower part 2. This plug connection is manually releasable in a straightforward way by retracting the upper part 3 upward in the height direction Z from the lower part 2. The plug connection is in this case formed between the drive wheel 6a and the driven element 7a. For 15 this purpose, the drive wheel 6a comprises a cylindrical bore 14a extending coaxially with the first rotation axis 8a. The cylindrical bore 14a is configured in the present case as a through-bore. The cylindrical bore 14a comprises a cylindrical lateral surface 15a. The driven 20 element 7a comprises a plug cylinder complementary to the cylindrical bore 14a, or functions as such a plug cylinder, and is correspondingly provided with a complementary cylindrical lateral surface 16a. The cylindrical lateral surface 16 of the driven element 7a 25 interacts during a rotation actuation of the drive wheel 6a in the circumferential direction about the first rotation axis 8a and axially along the height direction Z in a glidingly mobile fashion with the cylindrical lateral surface 15a of the cylindrical bore 14a. 30

[0063] In the embodiment shown, the control cam 9a is arranged as a kind of radial projection in the cylindrical bore 14a. In one embodiment (not shown), the control cam is instead arranged axially offset in the axial direction with respect to the through-bore 14a on 35 an upper side of the drive wheel 9a. The supporting 2021306851   01 Sep 2026 section 10a is formed by a radial indentation of the cylindrical lateral surface 16a of the plug cylinder. In one embodiment (not shown), the supporting section may be formed at a separate location from the plug cylinder. 5

[0064] The plug cylinder formed by the driven element 7a is inserted top downward in the height direction along the first rotation axis 8a into the cylindrical bore 14a. The first rotation axis 8a therefore coincides in the embodiment shown with a plug axis 17a of the plug 10 connection.

[0065] Because of the mirror-symmetrical configuration of the present embodiment, the plug connection between the upper part 3 and the lower part 2 is furthermore formed in the present case between the further drive 15 wheel 6b and the further driven element 7b. In this regard, the comments relating to the plug connection between the drive wheel 6a and the driven element 7a apply correspondingly. Separate reference to the sections required for the movement transmission and formation of 20 the plug connection on the further drive wheel 6b and the further driven element 7b will be omitted for the sake of the required brevity. Instead, reference is made to the relevant explanations in connection with the drive wheel 6a and the driven element 7a. 25

[0066] The height adjustment mechanism E in the present case furthermore comprises a worm gear 18,  19a,  19b preceding the cam gear. The worm gear 18,  19a,  19b comprises a worm drive shaft 18 and an outer circumferential section 19a, toothed complementarily to 30 the worm drive shaft 18, of the drive wheel 6a.

[0067] The worm drive shaft 18a is mounted rotatably on the lower part 2 about a second rotation axis 20 (Fig. 2) oriented perpendicularly to the height direction Z and 2021306851   01 Sep 2026 interacts for movement and force transmission with the toothed outer circumferential section 19a (Fig. 4). In the embodiment shown, the worm drive shaft 18 furthermore interacts with a complementarily toothed outer 5 circumferential section 19b of the further drive wheel 6b. The worm drive shaft 18 projects in the longitudinal direction X between the two drive wheels 6a, 6b. During a rotational movement of the worm drive shaft 18 about the third rotation axis 20, the two drive 10 wheels 6a, 6b are driven counter to one another about the respective first rotation axis 8a, 8b.

[0068] The worm gear 18, 19a, 19b formed in this way is configured to be self-retaining. Accordingly, the worm gear 18, 19a, 19b can be driven only by means of a drive- 15 side rotational movement of the worm drive shaft 18. Driving by means of a movement originating from one of the drive wheels 6a, 6b is, conversely, inhibited due to friction and / or transmission and is therefore not possible. 20

[0069] The worm drive shaft 18 comprises a rotation actuation section 21, which in the embodiment shown is provided with a tool face 22. The tool face 22 is a hex socket face, which is configured to interact with a conventional hex key provided for medical use. In one 25 embodiment (not shown), a crank formed by the rotation actuation section, an actuation wheel or the like is provided instead of the tool face 22. The rotation actuation section 21 is arranged at one end of the worm drive shaft 18 and is externally accessible in the 30 assembled state of the tibial trial implant 1 ready for use. At the other end, the worm drive shaft 18 comprises a toothing section 23, which interacts during a rotational movement of the worm drive shaft 18 with the toothed outer circumferential sections 19a, 19b. Between 35 the toothing section 23 and the rotation actuation 2021306851   01 Sep 2026 section 21, a stem section 24 extends in the axial direction.

[0070] The drive wheel 6a, the further drive wheel 6b and the worm drive shaft 18 are held between the upper 5 shell 2a and the lower shell 2b of the lower part 2, corresponding glide bearing faces, which for simplified graphical representation are denoted in the figures only in relation to the further drive wheel 6b, being provided in particular for mounting of the drive wheels 6a, 6b. 10 In respect of the glide bearing of the drive wheel 6a, the comments relating to the further drive wheel 6b apply correspondingly. The glide bearing face assigned to the further drive wheel 6b is formed by a through-bore 25b extending coaxially with the further rotation axis 8b 15 through the lower part 2. The through-bore 25b comprises - starting from an imaginary circular-cylindrical shape - a plurality of radial protrusions 26b. The protrusions 26b may also be referred to as flushing protrusions and allow simplified and therefore particularly hygienic 20 flushability of the lower part 2 with a liquid. The further drive wheel 6b comprises a lower radial hub 27b and an upper radial hub 28b, which are provided for gliding contact on the corresponding glide bearing faces of the upper shell 2a and of the lower shell 2b, 25 respectively.

[0071] Furthermore, a scale display S formed between the drive wheel 6a and the lower part 2 is provided, the arrangement of which may be seen with the aid of Fig. 5. The scale display S comprises a reading element 30 configured as a reading index, which is arranged both on the upper shell 2a and on the lower shell 2b. Additionally provided is a scale which may be seen in Fig. 6 and has a number sequence. The scale display S allows reading of the adjustment position of the upper part. 2021306851   01 Sep 2026

[0072] Moreover, an embodiment (not graphically represented) is provided in which the trial implant is provided for use in a (general) joint replacement operation and to this extent not necessarily for a knee 5 joint replacement operation. Accordingly, the lower part of this embodiment is provided not necessarily for tibial fixation but in general for bone fixation and / or support. The glide face, arranged on the upper side, of the upper part in this embodiment is provided for gliding 10 interaction with a further component fixed to the bone, which to this extent need not necessarily be a femoral component.

[0073] A further embodiment of a tibial trial implant 100 according to the invention is shown with the 15 aid of Fig. 10 to 18. The basic configuration and functionality of the tibial trial implant 100 largely correspond to the configuration and functionality of the tibial trial implant 1 according to Fig. 1 to 9. Primarily essential differences of the tibial trial implant 100 20 will therefore be discussed below. In other regards, in order to avoid repetition, reference is made to the description of the tibial trial implant 1.

[0074] The tibial trial implant 100 again comprises a lower part 102, an upper part 103 and a height adjustment 25 mechanism E’.

[0075] The lower part 102 (Fig. 14) is in the present case configured for indirect tibial fixation and accordingly interacts with a tibial trial plateau P. In a state ready for use, the lower part 102 is fitted 30 beforehand with its lower side 104 into a reception recess configured therefor (not denoted in detail) of the tibial trial plateau P. 2021306851   01 Sep 2026

[0076] In accordance with the lower part 2, the lower part 102 has a plate-like basic shape and a two-shell configuration with an upper shell 102a and a lower shell 102b. 5

[0077] In accordance with the upper part 3, the upper part 103 comprises a glide face 105 which is arranged on the upper side and has two partial glide faces 105a, 105b spaced apart from one another in the transverse direction Y. 10

[0078] The height adjustment mechanism E’ is - basically in accordance with the height adjustment mechanism E -actively connected on the one hand to the upper part 103 and on the other hand to the lower part 102 and allows relative displacement of the upper part 103 in relation 15 to the lower part 102 along the height direction Z. In this case, Fig. 10 shows by way of example a first adjustment position, which may also be referred to as a lower end location. In the lower end location, the tibial trial implant 100 has its minimum overall height and / or 20 thickness. Fig. 11 shows a second adjustment position, which may also be referred to as an upper end location. In this position, the tibial trial implant 100 assumes its maximum overall height and / or thickness.

[0079] The height adjustment mechanism E’ again 25 comprises at least one drive wheel 106a and one driven element 107a. The drive wheel 106a is mounted rotatably on the lower part 102 about a rotation axis (not denoted in detail) oriented parallel to the height direction Z and comprises a control cam 109a rising in the height 30 direction Z. The control cam 109a is formed in the embodiment shown by a control face 111a extending helically with a constant pitch coaxially around said rotation axis. 2021306851   01 Sep 2026

[0080] In the present case, the control cam 109a and / or the control face 111a are formed in the configuration of an internal screw thread IG. The internal screw thread IG is introduced into a cylindrical bore 114a of the 5 drive wheel 106a. The cylindrical bore 114a extends coaxially with the rotation axis of the drive wheel 106a.

[0081] The at least one driven element 107a is firmly connected to the upper part 103. In contrast to the driven element 7a of the tibial trial implant 1, the driven 10 element 107a is not, for instance, formed integrally on the upper part 103. Instead, there is a connecting element V assigned to the upper part 103 (Fig. 12), on which the driven element 107a is formed. The connecting element V is plugged together in a manner known per se 15 to the person skilled in the art releasably in the longitudinal direction and with a form fit in the transverse and height directions Y, Z with the upper part 103. The at least one driven element 107a comprises - basically in accordance with the driven element 7a - a 20 supporting section 110a which is glidingly supported on the control cam 109a. In the embodiment shown, the supporting section 110a is formed by a supporting face 112a extending helically with a constant pitch.

[0082] The supporting section 110a and / or the supporting 25 face 112a are configured as an external screw thread AG. The external screw thread AG is complementary to the internal screw thread IG. Expressed simply, the internal screw thread IG and the external screw thread AG form a kind of threaded spindle, by means of which the 30 rotational movement of the drive wheel 106a can be converted into a translational movement of the driven element 107a and therefore also of the upper part 103.

[0083] Expressed simply, the driven element 107a may be regarded as a screw and the drive wheel 106a as a nut. 2021306851   01 Sep 2026

[0084] The height adjustment mechanism E’ is — in a similar way to the height adjustment mechanism E -configured at least substantially, preferably fully, mirror-symmetrically. The height adjustment mechanism E’ 5 again comprises at least two drive wheels 106a, 106b and at least two driven elements 107a, 107b. These will also be referred to below as the first drive wheel 106a, second drive wheel 106b, first driven element 107a and second driven element 107b. In respect of the configuration and 10 functionality of the second drive wheel 106b, the comments above relating to the first drive wheel 106a apply correspondingly. Correspondingly, the same applies in respect of the functionality and configuration of the second driven element 107b. In order to avoid repetition, 15 reference is accordingly made to the disclosure relating to the first drive wheel 106a and the first driven element 107a.

[0085] The drive wheels 106a,  106b are preceded by a control wheel 118. The control wheel 118 is mounted 20 rotatably on the lower part 102 about a rotation axis oriented parallel to the rotation axes of the drive wheels 106a, 106b. The two drive wheels 106a, 106b and the control wheel 118 respectively comprise spur teeth 119a,  119b,  119. The spur teeth 119 of the control 25 wheel 118 are meshed with the spur teeth 119a of the first drive wheel 106a and with the spur teeth 119b of the second drive wheel 106b. In this way, the respective rotational movements are forcibly coupled and / or synchronized with one another. A rotational movement of 30 the control wheel 118 counterclockwise causes a rotational movement, respectively directed in the clockwise sense, of the first drive wheel 106a and of the second drive wheel 106b.

[0086] The spur teeth 119a, 119b of the two drive wheels 35   106a,  106b are identical in the embodiment shown in 2021306851   01 Sep 2026 respect of their respective number of teeth and the other tooth features. The spur teeth 119 of the control wheel 118 comprise a greater number of teeth than the spur teeth 119a, 119b. An outer diameter (not denoted in 5 detail) of the control wheel 118 is greater than the outer diameter of the drive wheels 106a, 106b.

[0087] In the embodiment shown, the control wheel 118 is configured for indirect manual actuation, which will be described in more detail below. In a further 10 embodiment, the control wheel is configured for direct manual rotation actuation.

[0088] The control wheel 118 in the present case comprises an internal screw thread IG’ in accordance with the drive wheels 106a, 106b. In correspondence with the 15 internal screw thread IG, the internal screw thread IG’ comprises a control cam (not denoted in detail), or more precisely a control face extending helically with a constant pitch. The internal screw thread IG’ of the control wheel 118 interacts with an external screw thread 20 AG’ of a further driven element 107c. The further driven element 107c will also be referred to below as the third driven element 110c. The external screw thread AG’ of the third driven element 107c again forms a supporting section, or more precisely a control face extending 25 helically with a constant pitch.

[0089] The control wheel 118 functions to this extent simultaneously as an additional third drive wheel. The internal screw thread IG’ and the external screw thread AG’ are mutually complementary. The sense of rotation of 30 the internal screw thread IG’ is opposite to the sense of rotation of the internal screw thread IG of the drive wheels 106a, 106b. The same applies correspondingly for the sense of rotation of the external screw thread AG’. Furthermore, the internal screw thread IG’ has a thread 2021306851   01 Sep 2026 pitch which is different to the thread pitch of the internal screw thread IG of the two drive wheels 106a, 106b. Accordingly, the thread pitch of the external screw thread AG' is also different to the thread pitch of the 5 external screw thread AG of the driven elements 107a, 107b.

[0090] The control wheel 118 is arranged centrally between the first drive wheel 106a and the second drive wheel 106b in the transverse direction Y. 10

[0091] The tibial trial implant 100 comprises a first display wheel 130a and a second display wheel 130b. The first display wheel 130a is assigned to the first drive wheel 106a and is coupled thereto so as to transmit movement. The second display wheel 130b is assigned to 15 the second drive wheel 106b and is coupled thereto so as to transmit movement. In a further embodiment, there is only a single display wheel. The configuration and function of the display wheels 130a, 130b are identical, so that only the first display wheel 130a will be 20 discussed below in order to avoid repetition. The disclosure in this regard also applies, mutatis mutandis, for the second display wheel 130b.

[0092] The first display wheel 130a is rotationally movably mounted on the lower part 102 and comprises a 25 scale S’ (not graphically represented in detail). The scale S’ is arranged on an outer circumference 131a of the first display wheel 130a. The scale S’ may, for example, be formed by a sequence of graduation lines or numbers. The scale S’ allows reading of the adjustment 30 position of the upper part 103. This is in correspondence with the scale S of the tibial trial implant 1 (Fig. 5).

[0093] By the movement-transmitting coupling, a rotational movement of the first drive wheel 106a is 2021306851   01 Sep 2026 converted into a rotational movement of the first display wheel 130a. The movement transmission may be configured to be continuous or intermittent, that is to say stepwise. In the embodiment shown, the latter is the 5 case.

[0094] By the intermittent movement transmission explained in more detail below, a continuous rotational movement of the first drive wheel 106a causes a stepwise rotational movement of the display wheel 130a. The 10  intermittent movement transmission is carried out in the present case by means of a first catch element 132a. The second drive wheel 106b and the second display wheel 130b are assigned a second catch element 132b.

[0095] The first catch element 132a is connected fixed 15 in rotation to the first drive wheel 106a. In the present case, the first catch element 132a is configured annularly, aligned coaxially with the first drive wheel 106a and fixed with a form, force and / or material fit (not shown in detail) on a lower side of the first 20 drive wheel 106a. The first catch element 132a interacts for movement transmission with a section provided therefor of the display wheel 130a. In the present case, the first catch element 132a comprises at least one, more precisely two, projections 133 protruding outward in the 25 radial direction. These are in the present case arranged offset from one another by 180° in the circumferential direction of the first catch element 132a. The first display wheel 130a comprises indentations 134 set back in the radial direction on its lower side (not denoted 30 in detail) (Fig. 16). For the intermittent movement transmission, the projections 133 engage in the indentations 134.

[0096] In the embodiment shown, a (continuous) full revolution of the first drive wheel 106a through 360° 2021306851   01 Sep 2026 causes a stepwise rotational movement of the first display wheel 130a by two increments. Since in the present case there are precisely six indentations 134 arranged offset from one another respectively by 60°, the 5 first display wheel 130a is accordingly moved in rotation respectively by two steps of 60° each.

[0097] It is to be understood that the comments above apply correspondingly in respect of the configuration and function of the second catch element 132b and of the 10 second display wheel 130b.

[0098] The control wheel 118 is assigned a latch element 135. In a manner described in more detail below, the latch element forms a releasable latch connection with the lower part 102, or more precisely its lower 15 shell 102b. The latch connection can be overridden and is established in defined rotational settings of the control wheel 118 and therefore of the two drive wheels 106a, 106b. In this way, a user receives tactile and / or acoustic feedback during the adjustment of the height 20 adjustment mechanism E’ as soon as a defined rotational setting and therefore height adjustment of the upper part 103 is reached.

[0099] In the embodiment shown, the latch element 135 is configured annularly and joined (in a manner not 25 shown) with a force, form and / or material fit onto a lower side of the control wheel 118. In this case, the latch element 135 is aligned coaxially with the control wheel 118 and can be rotated together therewith about its rotation axis. The latch element 135 interacts with a 30 complementary latch counter-element 139, which in the present case is formed as a circular-cylindrical recess, arranged on the lower part (Fig. 12). The circular-cylindrical recess is sunk into an upper side of the lower shell 102b. In the mounted state ready for use, the 2021306851   01 Sep 2026 catch element 135 is received in the circular-cylindrical recess 139. In the embodiment shown, the catch element 135 comprises two spring arms 136 arranged offset by 180°, on the terminal ends of which a latch 5 projection 137 is respectively formed. The latch projections 137 are resiliently mobile in the radial direction and interact with latch recesses 140 for the latching.

[00100] The tibial trial implant 100 furthermore 10 comprises a handle G shown with the aid of Fig. 17 and 18, which can be connected releasably (in a manner not described in detail) with the lower part 102. The handle G is used on the one hand for simplified handling of the lower part 102. On the other hand, the handle G 15 comprises actuation mechanics B, which are used for simplified and particularly ergonomic actuation of the height adjustment mechanism E’.

[0100] The handle G extends longitudinally between a proximal end 150 and a distal end 151. The actuation 20 mechanics B are in the present case arranged in the region of the distal end 151. For the releasable connection to the lower part 102, the handle G in the present case comprises two connecting elements, respectively in the form of a latch element 152, arranged at the distal end 25   151. In one embodiment (not shown), there is only one latch element. The two latch elements 152 are arranged spaced apart from one another in the transverse direction Y and, in a state connected to the lower part 102, interact respectively with a complementary 30 connecting element in the form of a latch counterelement 153. The latch counter-elements 153 are accordingly arranged spaced apart from one another in the transverse direction Y and in the present case are furthermore positioned on either side of the control 35 wheel 118. 2021306851   01 Sep 2026

[0101] In the embodiment shown, the latch elements 152 are respectively configured as a male latch element and the latch counter-elements 153 are respectively configured as a female latch element, or as a latch slot. 5 The latch elements 152 protrude in the distal direction from the distal end 151 of the handle G. The complementary latch elements 153 extend in the distal direction of the handle G into the lower part 102. The latch counterelements 153 are formed on the upper shell 102a. 10

[0102] The actuation mechanics B comprise an actuation wheel 154, which, in a state of the handle G connected to the lower part 102, is actively connected at least indirectly to the 106a, 106b so as to transmit forces and movement. The actuation wheel 154 is mounted rotatably 15 on the handle G about a rotation axis (not denoted in detail) and may also be referred to as a thumbwheel. A rotation of the actuation wheel 154 causes a rotation of the drive wheels 106a, 106b and therefore a corresponding height adjustment of the upper part 103. 20

[0103] In the embodiment shown, the actuation wheel is actively connected indirectly by means of a transmission wheel 155, mounted rotatably on the handle G, and the control wheel 118 to the drive wheels 106a, 106b. For this purpose, the actuation wheel 154 is provided with 25 spur teeth (not denoted in detail) which are engaged with spur teeth of the transmission wheel 155. The spur teeth of the transmission wheel 155 are in turn meshed with the spur teeth 119 of the control wheel 118. When the handle G is latched with the lower part 102, the teeth of the 30 transmission wheel 155 engage with the teeth 119 of the control wheel 118. When the handle G is retracted from the lower part 102, the meshing between the transmission wheel 155 and the control wheel 118 is released. 2021306851   01 Sep 2026

[0104] While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be 5 apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above-described exemplary 10 embodiments.

[0105] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion 15 of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0106] The reference in this specification to any prior publication (or information derived from it), or to any 20 matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavor to which this 25 specification relates.

Claims

1. A tibial trial implant for use in a knee joint replacement operation, comprising-    a lower part, which is provided for tibial fixation,an upper part, which is arranged above the lowerpart in a height direction and has a glide face that is arranged on the upper side and is provided for gliding interaction with a femoral component,- a height adjustment mechanism, which is actively 10 connected to the upper part and the lower part and bymeans of which the upper part can be guided displaceably relative to the lower part in the height direction betweena first adjustment position, in which the glide face15 is positioned at a first height above the lower part, and- a second adjustment position, in which the glide face is positioned at a second height above the lower part,wherein the height adjustment mechanism comprises a20 cam gear having at least one drive wheel, which is mounted rotatably on the lower part about a first rotation axisoriented parallel to the height direction and comprises a control cam rising in the height direction, and havingat least one driven element, which is firmly connected25 to the upper part and comprises a supporting section glidingly supported on the control cam, so that the upper part can be displaced by means of a rotational movement of the drive wheel between the first adjustment position and the second adjustment position,2021306851   01 Sep 2026wherein:a scale display is formed between the lower part andthe at least one drive wheel, which comprises a reading element and a scale and allows reading of the adjustment5 position of the upper part and / or of the height of the glide face, orthe at least one drive wheel is coupled so as totransmit movement to at least one display wheel which is rotationally mounted on the lower part, the display wheel10 comprising a scale which allows reading of the adjustment position of the upper part and / or of the height of the glide face.

2. The tibial trial implant as claimed in claim 1, wherein the control cam is formed by a control face 15 helically extending with a constant pitch coaxially around the first rotation axis.

3. The tibial trial implant as claimed in claim 1 or 2, wherein the supporting section is formed by a supporting face helically extending with a constant pitch coaxially 20 around the first rotation axis.

4. The tibial trial implant as claimed in one of thepreceding claims, wherein the upper part and the lowerpart are releasably plugged together by means of a plugconnection formed between the at least one drive wheel25 and the at least one driven element while being glidingly mobile relative to one another along a plug axis, the plug axis being oriented coaxially with the first rotation axis.

5. The tibial trial implant as claimed in claim 4, 30 wherein the at least one drive wheel comprises a cylindrical bore extending coaxially with the first2021306851   01 Sep 2026rotation axis, into which a complementary plug cylinder of the at least one driven element is releasably plugged so as to form the plug connection.

6. The tibial trial implant as claimed in one of the 5 preceding claims, wherein the height adjustment mechanism comprises a worm gear preceding the cam gear.

7. The tibial trial implant as claimed in claim 6, wherein the worm gear comprises self-retention.

8. The tibial trial implant as claimed in claim 6 or 7,10 wherein the worm gear comprises a worm drive shaft, which is mounted rotatably on the lower part about a second rotation axis oriented perpendicularly to the height direction, the worm drive shaft interacting with a toothed outer circumferential section of the at least one15 drive wheel or with a worm wheel preceding the at least one drive wheel.

9. The tibial trial implant as claimed in claim 8, wherein the worm drive shaft comprises on one end a rotation actuation section, which is configured for 20 manual and / or tool-driven rotation actuation of the worm drive shaft about the second rotation axis.

10. The tibial trial implant as claimed in one of the preceding claims, wherein the at least one drive wheel and / or the worm drive shaft is glidingly mounted 25 rotatably on a glide bearing face of the lower part, the glide bearing face comprising a plurality of radial flushing protrusions.

11. The tibial trial implant as claimed in one of the preceding claims, wherein the lower part is configured 30 as two shells and comprises an upper shell and a lower shell, the at least one drive wheel and / or the worm drive2021306851   01 Sep 2026shaft being held between the upper shell and the lower shell.

12. The tibial trial implant as claimed in one of the preceding claims, wherein the height adjustment mechanism 5 is configured at least substantially, preferably fully, mirror-symmetrically with respect to a vertical midlength plane, at least two drive wheels and at least two driven elements being provided.

13. The tibial trial implant as claimed in one of the 10 preceding claims, wherein there are at least two drive wheels and one control wheel, which respectively comprise spur teeth, the control wheel being spur-meshed with the two drive wheels.

14. The tibial trial implant as claimed in claim 13, 15 wherein the at least one control wheel comprises a further control cam, which interacts with a further supporting section of a further driven element.

15. The tibial trial implant as claimed in one of the preceding claims, wherein there is at least one catch 20 element connected fixed in rotation to the at least one drive wheel, which intermittently interacts with the display wheel so that a continuous rotational movement of the drive wheel causes a stepwise rotational movement of the display wheel.25   16. The tibial trial implant as claimed in claim 13 or14, wherein there is a latch device which comprises a latch element rotatably connected to the control wheel and a complementary latch counter-element arranged on the lower part, the latch element and the latch counter-30 element interacting in defined rotational settings of the control wheel while forming an overridable latch connection.2021306851   01 Sep 202617. The tibial trial implant as claimed in one of the preceding claims, wherein there is a handle releasably connectable to the lower part, having actuation mechanics, the actuation mechanics comprising an 5 actuation wheel which is actively connected to the atleast one drive wheel in a state of the handle connectedto the lower part.

18. The tibial trial implant as claimed in claim 17, wherein the handle comprises at least one connecting10 element arranged at its distal end, which is releasably connected to a complementary connecting element of the lower part in order to connect the handle to the lower part.

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