PATELLA PREPARATION SYSTEM

Abstract

A patella preparation system and method of using a patella preparation system. The patella preparation system includes a fixing device adapted to fixedly hold a patella, a guiding device linked to the fixing device to be moveable relative to the fixing device, preferably by translatory and/or tilting movements/motions, and an operation device for manually moving the guiding device relative to the fixing device individually and separately in a translatory and a tilting manner.

Claims

1.-15. (canceled)

16. A patella preparation system comprising: a fixing device adapted to hold a patella; a guiding device linked to the fixing device and moveable relative to the fixing device by translatory and tilting movements/motions; and an operation device for manually moving the guiding device relative to the fixing device individually and separately in a translatory and a tilting manner, wherein the patella preparation system further has a clamping device which is used to ease positioning and/or fixation of the guiding device at the patella which is connected to a quadriceps via a quadriceps tendon and with a tibia via a patella tendon, the clamping device being configured such as to be transitioned between a clamping position in which the clamping device encompasses each of the quadriceps tendon and the patella tendon and a released position in which the clamping device is neither fixed to the quadriceps tendon nor to the patella tendon.

17. The patella preparation system according to claim 16, wherein the clamping device includes a first clamping arm and a second clamping arm each having an upper arm element and a lower arm element which can be moved with respect to each other and which work together in a clamping manner, when the clamping device is in the clamping position, while in the clamping position the first clamping arm is encompassing the quadriceps tendon and the second clamping arm is encompassing the patella tendon.

18. The patella preparation system according to claim 16, wherein the clamping device is removably mountable to the patella preparation system via a clamping or an interlocking mechanism, the clamping device being automatically positioned with respect to the fixing device and hence to the patella via springs that are provided at the connecting portion.

19. The patella preparation system according to claim 16, wherein the fixing device is adapted to fixedly hold the patella.

20. A patella preparation system comprising: a fixing device being adapted to hold a patella, a guiding device which is linked to the fixing device to be moveable relative thereto by translatory and tilting movements/motions, and an operation device for manually moving the guiding device relative to the fixing device individually and separately in a translatory and a tilting manner, wherein the guiding device is adapted to guide a cutting instrument used to perform a resection on the patella, the fixing device comprises an upper fixing portion configured to contact the front surface of the patella and a lower fixing portion configured to contact the lower surface of the patella, the upper and the lower fixing portion being each connected to a central connecting portion, while the guiding device is movable in a direction parallel to the length axis of the connecting portion and is inclinable relatively to the upper and lower fixing portions, wherein the operation device comprises: a cutting height adjustment device which is configured to position the guiding device in a height with respect to the patella such that the cutting instrument can perform the resection on the patella with a preferred cutting height, and a cutting angle adjustment device for adjusting the angle of the guiding device with respect to at least the upper fixing portion of the fixing device and hence to the patella separately to the cutting height adjustment device such that the cutting instrument can perform the resection on the patella in a preferred angle.

21. The patella preparation system according to claim 20, wherein the guiding device is embodied in form of a disk with a concentric and hollow cylindrical hole defining an inner cylindrical surface the diameter of the hole being at least as large as the maximum diameter of the patella, while the disk is provided with a slot which extends at least partially along the periphery of the disk and extends in a radial direction of the disk from the shell surface of the disk to the inner cylindrical surface of the disk, while the slot is at least as high as being able to accommodate a working end of the cutting instrument, and the disk is fixedly connected with a cutting height adjustment axle.

22. The patella preparation system according to claim 21, wherein the disk is integrally and/or or perpendicularly connected with the cutting height adjustment axle.

23. The patella preparation system according to claim 21, wherein the cutting height adjustment device is provided with a rotary element having a first thread and being coupled to the cutting height adjustment axle in a freely rotatable manner, while the cutting height adjustment device is further provided with a guiding axle having a second thread which is configured to cooperate with the first thread of the rotary element such that when the rotary element is rotated the cutting height adjustment axle and with it the disk is moved along the length direction of the guiding axle.

24. The patella preparation system according to claim 23, wherein the cutting height adjustment axle is internally provided with a first guiding portion which is configured to be complementary to a second guiding portion externally provided on the guiding axle while both guiding portions are embodied such that they prevent a rotating movement of the cutting height adjustment axle with respect to the guiding axle.

25. The patella preparation system according to claim 23, wherein the guiding axle is provided with a scale which indicates a user of the patella preparation system the height of the guiding device with respect to the patella and hence indicates the cutting height.

26. The patella preparation system according to claim 23, wherein the first thread is an internal thread and the second thread is an external thread.

27. The patella preparation system according to claim 23, wherein when the rotary element is rotated around the length axis of the guiding axle, the cutting height adjustment axle and with it the disk is moved along the length direction of the guiding axle.

28. The patella preparation system according to claim 23, wherein the cutting angle adjustment device includes a rotating component integrally provided with a shaft which is configured to be inserted through the central connecting portion a gear wheel which is fixedly connected to the rotating component and further includes a toothed part configured to mesh with the gear wheel, while the toothed part is fixedly connected to a lever arm, which itself is fixedly connected with the guiding device and is rotatably supported via a bearing axle at a free end portion of the upper fixing portion, such that the guiding device is inclinable with respect to the upper fixing portion.

29. The patella preparation system according to claim 28, wherein the shaft is configured to be inserted through the central connecting portion in a direction perpendicular to the length axis of the connecting portion.

30. The patella preparation system according to claim 28, wherein the lever arm is fixedly connected with the guiding axle.

31. The patella preparation system according to claim 28, wherein the cutting angle adjustment device further includes a locking element which is configured to stop any rotation of the rotating component, when the locking element is reversibly brought in contact with the rotating component.

32. The patella preparation system according to claim 31, wherein the locking element has a locking part comprising a protruding portion and the shaft of the rotating component is provided with a circumferentially arranged groove, which is configured to receive the locking part of the locking element, when the locking element is brought in contact with the rotating component.

33. The patella preparation system according to claim 28, wherein the lever arm has at its distal free end a drill guiding element which is usable to guide a drill relatively to the upper fixing portion and hence to the patella, which drill guiding element is pivotally connected with the upper fixing portion via the bearing axle.

34. The patella preparation system according to claim 33, wherein the upper fixing portion has at its distal free end a receiving portion configured to receive the drill guiding element.

35. The patella preparation system according to claim 20, wherein the upper and the lower fixing portion are arranged parallel to each other.

36. A method for using the patella preparation system according to claim 20, comprising the following steps: a) positioning the patella preparation system with respect to a patella; b) fixing the patella preparation system with the fixing device at the patella; c) adjusting the height of the guiding device with respect to the patella using the cutting height adjustment device; and d) adjusting a cutting angle of the guiding device with respect to the upper fixing portion and hence with respect to the patella using the cutting angle adjustment device without releasing the fixation of the patella preparation system at the patella.

37. The method for using the patella preparation system according to claim 36, wherein step b) is performed with a clamping device that is used to ease positioning and/or fixation of the guiding device at the patella, the clamping device configured to be transitioned between: a clamping position, in which the clamping device encompasses a quadriceps tendon and a patella tendon; and a released position, in which the clamping device is neither fixed to the quadriceps tendon nor to the patella tendon.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] The disclosure is explained in more detail below on the basis of a preferred embodiment using figures. The figures are of a schematic nature and intended to improve the understanding of the disclosure. Same elements are referenced to with the same reference signs.

[0066] FIG. 1 shows a perspective view of a patella preparation system/instrument according to the disclosure being fixed to the patella.

[0067] FIG. 2 illustrates a mechanism with which a clamping device can be mounted to the patella preparation system.

[0068] FIG. 3 shows a longitudinal sectional view of the patella preparation system with springs arranged at a connecting portion of the patella preparation system.

[0069] FIG. 4 is a side view of the patella preparation system.

[0070] FIG. 5 shows a perspective sectional view of a cutting height adjustment device of the patella preparation system.

[0071] FIG. 6 illustrates a perspective view of the patella preparation system from a user's view.

[0072] FIG. 7 shows a side view of the patella preparation system and especially a cutting angle adjustment device, where a toothed part of the cutting angle adjustment device is not inclined/tilted.

[0073] FIG. 8 shows a side view of the patella preparation system and especially the cutting angle adjustment device, where the toothed part of the cutting angle adjustment device is inclined/tilted.

[0074] FIG. 9 illustrates a sectional side view of the cutting angle adjustment device in detail.

[0075] FIG. 10 is an exploded view of the patella preparation system according to the disclosure and especially of the main components of the cutting angle adjustment device.

DETAILED DESCRIPTION

[0076] In this application, when it can be read that a first element is fixedly connected to a second element, the wording fixedly connected to means that when the first device is moved in an arbitrary way, the second device is moved together with the second device in the same way.

[0077] FIG. 1 shows a perspective view of a patella preparation system/instrument (PPS) 1, which is illustrated in a position where it is fixed to a patella 2. The patella 2 is at a first position connected with a quadriceps (not shown) via a quadriceps tendon 2a and is at a second position, which is diametrically opposed to the first position, connected with a tibia (not shown) via a patella tendon 2b. The PPS 1 includes a guiding device/unit 3 preferably in form of a circular disk or ring 3 with a concentrically arranged through hole 4 providing a circular opening. The disk/ring 3 does not have to be a perfect circular form but can also be truncated. The disk/ring 3 does not even have to be circular but can also have a, for example, rectangular shape. The diameter of the hole 4 is at least as large as the maximum diameter of the patella 2 or lager such that the disk/ring 3 can be arranged around the patella 2, when the PPS 1 is positioned and/or fixed at/to the patella 2.

[0078] The disk/ring 3 is provided with a slot 5 which extends in radial and circumferential direction of the disk/ring 3. The slot 5 does not have to be arranged over the whole circumference of the disk/ring 3 but can be, for example, two parted. In this case, a first piece 5a of the slot 5 may at least be arranged such that it extends in a region near to the first position where the patella 2 is connected with the quadriceps tendon 2a, when the PPS 1 is positioned at the patella 2. Then, a second piece 5b of the slot 5 may be diametrically opposed to the first piece 5a of the slot 5 such that it is arranged in a region near to the second position where the patella 2 is connected with the patella tendon 2a, when the PPS 1 is positioned at the patella 2.

[0079] The slot 5 extends in a radial direction of the disk/ring 3 from the shell surface of the disk/ring 3 to its inner cylindrical surface provided by the hole 4. The height of the slot 5 is at least so high that the slot 5 can accommodate a working end of a cutting device 6, such as a saw blade of a surgical saw, etc. The cutting device 6 is separately provided from the PPS 1 and not part of the disclosure.

[0080] The disk/ring 3 is fixedly, especially integrally, connected with a socket-like cutting height adjustment axle 7. In the embodiment of the PPS 1 according to FIG. 1, the disk/ring 3 is connected with the cutting height adjustment axle 7 in a perpendicularly manner. The cutting height adjustment axle 7 is here configured as a kind of a sleeve or a dome which may have an inclined outer surface and/or may be provided with openings on its outer circumferential surface. In other words, the cutting height adjustment axle 7 is preferably formed as a U-shaped socket comprising two parallel distanced legs 7a, 7b which are interconnected with each other at their one (upper) ends by a bar/yoke 7c and which are connected to the disk/ring 3 at their other (lower) ends in a perpendicular manner. The connection of the cutting height adjustment axle 7 with the disk/ring 3 may be strengthened by reinforcing ribs or stiffeners 8. Here, two reinforcing ribs/stiffeners 8 are arranged between the disk 3 and the cutting height adjustment axle 7.

[0081] Moreover, the PPS 1 includes a fixing device/unit 9. The fixing device 9 includes an upper fixing portion (upper thrust plate arrangement) 10, a lower fixing portion (lower thrust plate arrangement) 11 which is not illustrated in FIG. 1 and a central connecting portion/part 12. The upper fixing portion 10 is fixedly and especially integrally connected with the central connecting portion 12 at an upper connecting portion 12a (not particularly illustrated in FIG. 1) of the connecting portion 12 preferably by two parallel distanced connecting arms. The lower fixing portion 10 is fixedly and especially integrally connected with the central connecting portion 12 at a lower connecting portion 12b (not particularly illustrated in FIG. 1) of the connecting portion 12. The upper connecting portion 12a and the lower connecting portion 12b are movable relative to each other in a slidable, preferably telescopic manner along the length axis of the connecting portion 12. In this way, the upper fixing portion 10 can be moved/distanced with respect to the lower fixing portion 11 to fix/clamp the patella 2 in between, when the PPS 1 is positioned at the patella 2. Here, the upper connecting portion 12a is configured to be insertable into the lower connecting portion 12b.

[0082] The upper fixing portion 10 is arranged above the upper surface of the patella 2, when the PPS 1 is positioned at the patella 2, and the lower fixing portion 11 is arranged below the lower surface of the patella 2, when the PPS 1 is positioned at the patella 2. In a case, where the PPS 1 is positioned at the patella 2, in a fixing position the lower surface of the upper fixing portion 10 contacts/fixes the upper surface of the patella 2 and the upper surface of the lower fixing portion 11 contacts/fixes the lower surface of the patella 2.

[0083] Furthermore, in the embodiment shown in FIG. 1, the PPS 1 includes a clamping device 13, which will be described in detail later. Further, the PPS 1 includes an operation device, having a cutting angle adjustment device 17, which will be explained in detail later and a cutting height adjustment device 14 comprising a rotary component/element (knop) 15, a spindle 16 and the cutting height adjustment axle 7, which will be explained in detail hereinafter.

[0084] Hence, the operation device here includes the cutting height adjustment device 14 for separately and individually adjusting the height of the guiding device 3 in relation to the patella 2 and includes the cutting angle adjustment device 17 for separately and individually adjusting the inclination/tilting of the guiding device 3 in relation to the patella 2. Here, the guiding device 3 is movable in a translatory direction of (the connecting portion 12 of) the PPS 1 by the cutting height adjustment device 14 and is separately therefrom inclinable/tiltable by the cutting angle adjustment device 17 in a direction of the up-and-down direction (connecting portion 12 of) of the PPS 1, meaning a direction between the lower fixing portion 11 and the upper fixing portion 10.

[0085] The PPS 1 is further provided with a handle 18, which is formed like the handle of a forceps. The handle 18 has a movable handle arm or branch 18a and a fixed handle arm or branch 18b. The movable handle arm 18a is pivotably connected to the fixed handle arm 18b, which latter one is fixed to the lower connecting portion 12b of the connecting portion 12. Hence, the movable handle arm 18a being pivotably arranged with respect to the fixed handle arm 18b is interconnected with the upper connection portion 12b of the central connection part 12. Accordingly, if the handle 18 is manually actuated, the upper and lower connection portions 12a, 12b of the central connection part 12 are moved relative to each other such that the upper and lower thrust plates 10, 11 are distanced and/or converged.

[0086] Finally, the fixing device comprises a manually actuatable locking mechanism, having a rest lever 19 pivotably supported by the lower connection portion 12b and which is in locking contact with the upper connection portion 12a in a locking state. The fixing device 9 can, therefore, be transitioned from the fixing position to an open position, in which the lower fixing portion 11 is no longer in contact with the lower surface of the patella 2, via the rest lever 19 if the rest lever is moved from its locking state into a release state. In this case the upper fixing portion 10 can be moved relative to the lower fixing portion in a translatory manner as the upper fixing portion 10 is fixedly connected with the upper connecting portion 12a and the lower fixing portion 11 is fixedly connected to the lower connecting portion 12b. As the upper connecting portion 12a is movable in a translatory manner with respect to the lower connecting portion 12b, the upper fixing portion 10 is moved together with the upper connecting portion 12a with respect to the fixed lower fixing portion 11.

[0087] Therefore, the upper connecting portion 12a may be provided with a corrugated outer shell surface (bolt) which is complementary to a corrugated inner surface (hole) of the lower connecting portion 12b at the region where the connecting portion 12b accommodates the upper connecting portion 12a, see in detail FIG. 3.

[0088] FIG. 2 is a perspective view of the clamping device 13 and the upper connecting portion 12a.

[0089] The clamping device 13 may be connected removably via the upper connecting portion 12a with the PPS 1 to ease positioning of the guiding device 3 and hence the cutting device 6 with respect to the fixing device 9 (and hence to the patella 2). The clamping device 13 can be transitioned between a clamping position in which the clamping device 13 encompasses the quadriceps tendon 2a and the patella tendon 2b and a released position in which the clamping device 13 is not fixed to and has no contact with the quadriceps tendon 2a and the patella tendon 2b.

[0090] The clamping device 13 is formed to be arc-like. The clamping device 12 consists here of three parts: [0091] a first arc-shaped clamping arm 13a, [0092] a second arc-shaped clamping arm 13b forming a U-like fork together with the first clamping arm 13a and [0093] a connection part or central coupling piece 13c.

[0094] The connection clamping part 13c is arranged between the first clamping arm 13a and the second clamping arm 13b and connects both arms with each other. For example, each arm 13a, 13b is connected with the connection part 13c via a plug-like connection.

[0095] Each clamping arm 13a, 13b has an upper arm element 20 and a lower arm element 21 which can be moved with respect to each other and which work together in a clamping manner when the clamping device is in a clamping position. In a clamping position, the first clamping arm 13a is encompassing the quadriceps tendon 2a and the second clamping arm 13b is encompassing the patella tendon 2b. Alternatively, the upper and lower arm elements are fixedly interconnected with each other in a leaf spring manner.

[0096] The connecting clamping part 13c is provided with a plug 22 which may be formed in a L-like manner. The upper connecting portion 12a is at least partly formed like a (hollow) sleeve which has a closed/continuous top surface. Inside the sleeve there is provided a groove 23 which extends in a longitudinal direction of the sleeve. Inside this groove 23 a clamping portion/part 24 and a pressing portion/part 25 are arranged next to each other. The pressing portion/part 25 is arranged above the clamping portion/part 24 (the pressing portion is arranged between to the inner top surface of the upper connecting portion 12a and the clamping portion 24). The pressing portion 25 and the clamping portion 24 work together to form a recess (not particularly shown in FIG. 2). This recess is at least as large such that it can accommodate at least the portion of the plug 22 which is protruding from the connecting clamping part 13c (protruding portion). This protruding portion is compatibly insertable or snappable into the recess.

[0097] When the protruding portion of the plug 22 is arranged inside of the recess the clamping device 13 is mounted to the PPS 1. If a user of the PPS 1 wants to remove the clamping device 13, he can press the pressing portion 25 down to the clamping portion 24. Then the recess gets so large that it releases the protruding portion of the clamping device 13. With such a configuration, the clamping device can be mounted to or removed from the PPS 1 very easily and quickly.

[0098] The clamping portion 24 and the pressing portion 25 are arranged within the inner space of the upper connecting portion 12a to be slidable in a longitudinal direction of the upper connecting portion 12a.

[0099] FIG. 3 is a longitudinal sectional view of the PPS 1. For ease of understanding, the guiding device/disk/ring 3 is not illustrated in this FIG. 3. Here, the clamping device 13 is fixed to the PPS 1. It is visible that the upper connecting portion 12a accommodates two springs 26, 27 in its inner space (cannon). The first spring 26 is arranged and fixed between the upper end of the upper connecting portion 12a and the top of the pressing portion 25. The second spring 27 is arranged and fixed between the movable arm 18a and the lower surface of the clamping portion 24.

[0100] When the movable handle part 18a is pressed towards the fixed handle part 18b (by the user), the spring 26 is stretched and hence pulls the clamping device 13 downwards (in a direction towards the bottom part of the connecting portion 12) in a length direction of the connecting portion 12. Hence, the position of the clamping device 13 can easily and automatically be changed with help of the springs 26, 27 and hence be arranged appropriately for the patella to be operated with the PPS 1.

[0101] Furthermore, in FIG. 3 it can been seen that the lower surface of the upper fixing part (upper thrust plate arrangement) 10 and the upper surface of the lower fixing part (lower thrust plate arrangement) 11 are each provided with a plurality of prongs. These prongs help to fix the patella 2 between the upper and the lower fixing parts 10, 11, when the PPS 1 is fixed to the patella 2.

[0102] FIG. 4 is a side view of the complete PPS 1 with the clamping device 13 fixed to the PPS 1. Here, it can be seen that the upper fixing part 12a is provided with a scale which indicates the height of the patella in mm. This height scale indicates at which height the PPS 1 is fixed to the patella 2.

[0103] FIG. 5 shows a perspective sectional view of the cutting height adjustment device 14 of the PPS 1 connected to the guiding axle 7. As already mentioned before, the cutting height adjustment device 14 comprises the rotary element 15 and the (U-shaped) cutting height adjustment axle 7. Here, the rotary element 15 is configured as a knob with a disk-like upper (manually operable) plate 28, a connecting throat 29 and a disk-like lower plate 30. The connecting throat 29 and the lower plate 30 configure a flange with which the rotary element 15 is connected with an inner space of the cutting height adjustment axle 7 at its upper part. Accordingly, the rotary element 15 is connected with the cutting height adjustment axle 7 in such way that it is freely rotatable with respect to the cutting height adjustment axle 7 but cannot be shifted in axial direction relative to the cutting height adjustment axle 7. The cutting height adjustment axle 7 is hence provided with a recess that can accommodate the flange of the rotary element 15.

[0104] The guiding axle 16 is formed like a partly threaded rod or spindle and is, on its outer surface, provided with a scale showing the user of the PPS 1 the actual cutting height in mm. The inner surface of the at least partially hollow cutting height adjustment axle 7 is provided with a first guiding portion 31. This first guiding portion 31 is configured to be complementary to a second guiding portion 32, which is externally provided on the guiding axle/spindle 16 at a lower part of the guiding axle 16. Both guiding portions are embodied such that they prevent a rotating movement of the cutting height adjustment axle 7 with respect to the guiding axle 16. The cutting height adjustment axle 7 is connected/linked/coupled to the guiding axle 16 in such way that the cutting height adjustment axle 7 can be moved relative to the (vertically fixed) guiding axle 16 along its longitudinal direction.

[0105] Here, the first guiding portion 31 is configured as a rail with a flat sliding surface on which a flat sliding surface of the first guiding portion 32, which is formed in a box-like manner, can slide, when the rotary element 15 is rotated.

[0106] Furthermore, the rotary element 15 is provided with a concentrically arranged through hole extending in its longitudinal direction which is provided with a first thread. The guiding axle/spindle 16 is provided with a second thread on its outer surface. The first thread and the second thread are meshing with each other.

[0107] Accordingly, when the rotary element 15 is rotated around the length axis of the guiding axle/spindle 16, the first thread meshes with the second thread such that the rotary element 15 and with it the cutting height adjustment axle/socket 7 is moved downwards or upwards along the longitudinal direction of the guiding axle/spindle 16. As the rotary element 15 is freely rotatable with respect to the cutting height adjustment axle 7 and the cutting height adjustment axle 7 is connected/linked to the guiding axle 16 in a slidable manner, the cutting height adjustment axle 7 is moved upwards or downwards together with the rotary element 15 without being rotated. As the cutting height adjustment axle 7 is fixedly connected to the disk/ring 3 of the guiding device 3, the disk/ring 3 is moved together with the cutting height adjustment axle 7. In this way, the height of the disk/guiding device 3 of the PPS 1 with respect to the patella 2 and hence the cutting height of the PPS 1 can be adjusted with the such configured cutting height adjustment device 14.

[0108] FIG. 6 illustrates a perspective view of the PPS 1 from a perspective of the user of the PPS 1. It is visible that the scale of the guiding axle 16 is directed to the user.

[0109] FIG. 7 shows a side view of some elements of the PPS 1 and especially shows the section of the PPS forming the cutting angle adjustment device 17. In this figure, for the ease of understanding, only the upper fixing portion 10, the lower fixing portion 11, the connecting portion 12, the guiding axle 16 and the cutting angle adjustment device 17 are illustrated.

[0110] In FIG. 7 a working/lever arm 33 is illustrated which (at its middle portion) is fixedly connected with the guiding axle 16, here in a perpendicularly manner. The working/lever arm 33 is pivotally linked with the upper fixing portion 10 at their free (distal) end portions, respectively, wherein the working/lever arm 33 and extends towards the central connection part 12 between the two parallel distanced connection arms of the upper fixing portion. Accordingly, the working/lever arm 33 and, therefore, the guiding axle/spindle 16 (being fixedly connected with the working/lever arm 33) can pivot upward and downward around the linkage at the free/distal end portion of the upper fixing portion 10.

[0111] The cutting angle adjustment device 17 comprises a rotating component (knop) 34 integrally provided with a rotating shaft 35, which is insertable/inserted into an opening within the upper fixing portion 12a of the central connection part 12, the opening extending through the upper fixing portion 12a along its transverse direction. The distal/free end of the shaft 35 is fixedly connected to a gear wheel (spur-gear) 36. The gear wheel 36 is configured to mesh with a divided circle-like toothed part 37 which is fixedly connected to the working/lever arm 33 preferably via a connection pin 38. S already stated above, the working/lever arm 33 is pivotably supported at the upper fixing portion 10 by a bearing/pivoting axle 39. In this case, the length axis of the working/lever arm 33 and the length axis of the upper fixing portion 10 are parallel, especially identical, to each other.

[0112] In FIG. 7, a finger of a user U is shown. The arrow A shows the direction the user U can turn the rotating component/element 34 into. The arrow B indicates that a locking element 40 is in an Up-position, in which the locking element 40 is not in contact with the shaft 35 of the rotating component/element 34. The arrow C indicates the direction in which the toothed part 37 is going to move when the rotating component/element 34 is rotated in the direction of arrow A. This means that in case the rotating element/knop 34 is manually turned/rotated, the working/lever art 33 is pivoted around the pivoting axle 39 thereby tilting the guiding axle/spindle 16 and the cutting height adjustment axle 7 at which the guiding disk/ring 3 is fixed.

[0113] FIG. 8 shows the assembly of FIG. 7 when the rotating component/element 34 has been rotated in the direction of the arrow A of FIG. 7 around the length axis of the shaft 35 coming from the position shown in FIG. 7. In this case, the gear wheel 36 is rotated together with the shaft 35 of the rotating component 34 while the locking element 40 is still not in contact with the shaft 35 (release position). As the gear wheel 36 meshes with the toothed part 37, the toothed part 37 into the direction indicated by arrow C in FIG. 7. As the toothed part 37 is fixedly connected to the working/lever arm 33, the working/lever arm 33 is rotated around the rotation axle 38 together with the toothed part 37. The working/lever arm 33 is rotatably supported by the bearing axle 39 with respect to the upper fixing part 10. The working/lever arm 33 is perpendicularly and fixedly connected with the guiding axle 16. Due to the rotation of the working/lever arm 33 around the rotation axle 38, the guiding axle/spindle 16 is inclined with respect to the upper fixing portion 10.

[0114] As the cutting height adjustment axle 7 (illustrated as a hatched line in FIG. 8) is fixedly connected with the guiding axle 16 and the guiding device 3 (illustrated as a hatched line in FIG. 8) is fixedly and especially perpendicularly connected with the cutting height adjustment axle 7, the guiding device 3 is also is inclined with respect to the upper fixing portion 10.

[0115] Hence, when rotating the rotating component/element 34 around the length axis of its shaft 35, the length axis D of the working arm 33 is inclined with respect to the length axis E of the upper fixing portion 10. Then, as well the length axis F of the guiding device 3 is inclined with respect to the length axis E of the upper fixing portion 10. Thus, when rotating the rotating component 34 around the length axis of its shaft 35, the angle of the guiding device 3 with respect to the upper fixing portion 11 has been changed and hence the angle of the guiding device 3 with respect to the patella 2 has been changed, when the PPS 1 is positioned and/or fixed to the patella 2. The PPS 1 with the such configured cutting angle adjustment device 17 allows an amendment of the cutting angle/cutting slope without removing the PPS 1 from the patella 2.

[0116] After a preferred cutting angle has been adjusted with the cutting angle adjustment device 17 (hence, after the rotating component 34 has been rotated), the locking element 40 can be brought in contact with the shaft 35 to stop any further (unintended) rotation of the rotating component 34.

[0117] FIG. 9 illustrates a sectional side view of the cutting angle adjustment device in detail. Here, it can be seen, that the toothed part 37 is provided with a scale which indicated the current cutting angle/slope/inclination in .

[0118] FIG. 10 is an exploded view of the PPS and especially of the main components of the cutting angle adjustment device 17. In this view, it is visible that the locking element 40 is configured as a pin, which is configured to be insertable into a groove 41 of the shaft 35. The groove 41 is circumferentially arranged around the shaft 35. The top surface of the upper fixing part 12a is provided with a hole which can accommodate the pin-like locking element 40. The hole has to be configured such that the locking element 40 can be inserted into the groove 41 of the rotating component 34.

[0119] Furthermore, it can be seen that the rotation axle 38 is also configured as a pin. The working arm 33 is provided with a working end 42 at its distal end. This working end 42 can be used as a guide for a drill (not shown). In this case, the working end 42 is provided with through holes that can guide the drill(s) towards the patella 2. To ensure stable holding of the working end 42, the upper fixing part 10 is provided with a receiving portion 43 at its distal end configured to receive the working end 42.