Surgical milling cutter with improved chip removal

Abstract

The present disclosure relates to a surgical milling cutter, the surgical milling cutter comprising a shaft (17, 35, 47, 57) for rotational drive coupling to a drive unit about an axis of rotation (19, 37, 49, 59) extending longitudinally of the shaft (17, 35, 47, 57), and a cutter head (19, 37, 49, 59) disposed distally of the shaft (17, 35, 47, 57). and (8, 36, 48, 58), wherein the milling cutter head (18, 36, 48, 58) has at least two teeth (21, 22, 39, 40) with respective cutting edges (23, 24, 41, 42, 50a, 50b, 60a, 60b) for a rotary tissue removal device, the cutting edges (23, 24, 41, 42, 50a, 50b, 60a, 60b) being adapted to remove tissue in both a distal and a transverse direction. chip spaces (30a, 30b, 54a, 54b) are formed as free spaces between adjacent teeth (21, 22, 39, 40) in the circumferential direction, and each chip space (30a, 30b, 54a, 54b) is located on the side of the rotation axis (19, 37, 49, 59) and is located between the respective cutting edges (23, 24, 41, 42, 50a, 50b, 60a, 60b). at the side of the axis of rotation (19, 37, 49, 59) facing the cutting edge (23, 24, 41, 42, 50a, 50b, 60a, 60b) to a region at the side of the axis of rotation (19, 37, 49, 59) facing away from the cutting edge (23, 24, 41, 42, 50a, 50b, 60a, 60b).

Description

[Technical Field]

[0001] The present disclosure relates to a surgical milling cutter having a shaft for rotationally driving coupling with a drive unit about a rotation axis extending longitudinally of the shaft, and a cutter head disposed distally of the shaft, the cutter head having at least two teeth with cutting edges for rotationally removing tissue, each tooth designed to remove tissue in both a distal and a transverse direction and starting from a distal portion of the milling cutter's rotation axis and extending radially outward in a proximal direction, wherein a chip space is defined as a clearance between adjacent teeth in the circumferential direction in the milling cutter. The present disclosure also relates to a method for obtaining bone and / or cartilage material, in which bone and / or cartilage are machined with a tool and the obtained removed bone / cartilage material is collected, optionally stored, and used for bone material growth. [Background technology]

[0002] Surgical milling cutters are commonly known in the prior art and are used to remove hard tissue, such as bone or cartilage, by rotating around a longitudinally extending axis of rotation. A rose-head burr or rose drill is a milling cutter tool with a roughly spherical cutter head and a large number of teeth, with 6 to 14 cutting edges, depending on the diameter. The teeth and their cutting edges converge at the distal end of the cutter head on the axis of rotation of the milling cutter. As a result of the large number of teeth, the tooth height decreases toward the distal end region and becomes zero directly at the axis of rotation. This means that there is no intertooth space between the individual teeth at or near the distal end of the milling cutter. By appropriate geometric optimization, it may be possible to create a somewhat larger tooth height, and therefore a somewhat larger chip space, in the distal end region of the cutter head. However, even with such optimization, there are drawbacks, such as difficult chip removal, resulting in relatively high temperatures, and severely limited or non-existent visibility at the site, because the cutting edges meet at the center, i.e., the axis of rotation of the milling cutter head.

[0003] The teeth / cutting edges of such rose drills are typically produced by grinding. For this purpose, so-called pointed discs are used. These typically have a grinding angle of 60° to 90°, and the interdental spaces are formed by removing material with the cutter head. The depth of the pointed disc's penetration into the cutter head is set so that a tooth with a corresponding cutting edge is formed from the front of the tooth in the previous interdental space and the back of the tooth in the next interdental space. To prevent the pointed disc from penetrating the cutter shaft when grinding the proximal region of the cutter head, the teeth are usually inserted into the cutter head in a twisted, or spiral, manner. In this way, the teeth or cutting edges in the proximal region of the cutter head can be formed somewhat closer to the axis of rotation. The pointed disc is adjusted so that the rake angle of the cutting edge is negative, typically between -10° and -40°. The clearance angle of the cutting edge is correspondingly very large, between 40° and 70°.

[0004] The disadvantage of such rose drills in terms of production is that the high number of teeth / cutting edges increases the running time of the grinding machine during production, which leads to higher production costs.

[0005] A practical disadvantage of this type of milling cutter tool is that, due to the relatively sharp teeth and their large number involved in production, so-called "chat" can frequently occur when processing bone, which becomes apparent when the milling cutter bounces uncontrollably away from the area to be machined, making accurate work impossible or very difficult.

[0006] A further drawback is caused by the relatively small interdental spaces between the teeth in the distal end region, which function as chip spaces. Bone material removed during machining accumulates in the chip spaces and must be removed to make room for newly removed material. If material movement through the interdental spaces is insufficient, the chip spaces become blocked, and the cutting edges are shielded by the accumulated material. As a result, further material removal becomes impossible. This is one of the reasons why it is difficult to achieve satisfactory cutting performance and cutting force in the axial direction with such milling cutter heads. This drawback is particularly serious because surgical procedures must often be performed deep (i.e., axially) to remove axial bone. Blocked cutting edges or interdental spaces in the center of the cutter head are difficult or impossible for surgeons to detect because the cutter head itself blocks their view. Clearing blocked interdental spaces during surgery is extremely difficult. Once an interdental space is blocked, continuing to work on the bone can lead to increased pressure and friction, which in turn leads to increased temperatures. This is particularly deadly because temperatures just above 45°C can already cause the patient's proteins to coagulate, with known adverse effects.

[0007] To mitigate the latter problem, such milling cutters are flushed or cooled with liquid during operation. The liquid aids in chip removal and reduces heat at the machining site. However, if cutting performance is insufficient and liquid is added, heat may build up in certain locations, potentially solidifying the machined bone. Furthermore, if excessive heating occurs in material located within the interdental space, the material may solidify there as a result of the heating and be very difficult to remove.

[0008] A further drawback may be that the shape of the milling cutter prevents the surgeon from seeing the location, i.e., the surgical field in the area of ​​the tool tip. This applies to both driven and stationary milling cutters. Therefore, in order to closely examine the location, the milling cutter must be at least partially, if not completely, removed from the operating field.

[0009] Finally, the many deep interdental spaces of such rose drills and rose-head burs are difficult to clean as part of routine clinical practice.

[0010] In addition to the milling cutters mentioned above, milling cutter tools with two cutting edges, such as so-called olive cutters or neurocutters, as well as so-called twin-cutter milling tools, are known in medical technology, but their chip space is significantly smaller.

[0011] A relatively large chip space is provided by a surgical milling cutter with only one cutting edge, a so-called single cutter. An example of such a device is disclosed in U.S. Patent Application Publication No. 2017 / 0150974. However, because the cutter head has only one cutting edge and is designed asymmetrically / eccentrically with respect to the axis of rotation, its mass is distributed eccentrically, causing imbalance during operation. This results in rough and unstable operation of the milling cutter tool, high loads on the handpiece, especially its bearings, and increased operating noise. Summary of the Invention [Problem to be solved by the invention]

[0012] Against this background, it is an object of the present disclosure to reduce the above-mentioned drawbacks of the prior art and to provide a milling cutter for high-speed applications in medicine, in particular for machining bone, with improved cutting performance in the axial direction, low heat generation, and improved chip removal from the distal end region. A further object is to provide a milling cutter that is particularly easy to clean and is particularly suitable for obtaining tissue material such as bone or cartilage for the purpose of obtaining further artificial material. Finally, the present disclosure aims to provide an improved method for obtaining bone and / or cartilage material. [Means for solving the problem]

[0013] This object is solved according to the present disclosure by a surgical milling cutter as set forth in claim 1, namely a surgical milling cutter comprising a shaft, in particular comprising a surgical handpiece, for rotational drive coupling to a drive unit about an axis of rotation extending in the longitudinal direction of the shaft, and a cutter head arranged distally of the shaft, the cutter head having at least two teeth with respective cutting edges for rotationally removing tissue, the cutting edges each being designed to remove tissue both in the axial and / or distal direction and in the radial and / or transverse direction, chip spaces, also called inter-tooth spaces, being formed in each case as clearances between circumferentially adjacent teeth, each chip space extending from the cutting edge to an area on the side of the axis of rotation facing the respective cutting edge, at least in the distal part of the milling cutter, facing away from the corresponding cutting edge. According to the present disclosure, each chip space is formed on the cutting edge side of the rotation axis of the milling cutter and can be said to extend at least in a distal region on the side of the rotation axis facing away from the respective cutting edge. A surgical milling cutter according to the present disclosure is preferably designed to be rotationally symmetrical about its rotation axis and / or to have a mass distribution symmetrical about the rotation axis, so that it can operate without imbalance.

[0014] A particular advantage of the present disclosure is that the design of the teeth or cutting edges ensures that the interdental space / chip space at or near the axis of rotation (tip) of the cutter head is as large as possible. This ensures the evacuation of material removed with the milling cutter (especially bone dust and bone fragments). Liquid-based support for material evacuation can essentially be advantageously reduced in most cases. Solidification of the processed bone and removed material in the interdental spaces as a result of excessive heating can be reliably avoided. Therefore, the milling cutter is particularly easy to clean due to the good accessibility of the teeth in the interdental spaces and at the cutting edges. Another particular advantage of the present disclosure is that the shape of the milling cutter according to the present disclosure and its chip space allow the surgeon to have a particularly good view of the area without having to remove all or part of the milling cutter from the surgical field. Finally, the significantly lower heat generation reliably avoids uneven heating of bone material during processing with the milling cutter according to the present disclosure, especially to temperatures above 45°C. An advantageous consequence of this is that the removed bone material is undamaged / undamaged and therefore available for further use, for example bone material growth.

[0015] Advantageous embodiments of the present disclosure are defined in the dependent claims and are explained in more detail below.

[0016] One embodiment is characterized in that the cutting edges are each arcuate from the distal radially inward to the proximal radially outward. They may also be approximately semicircular and / or extend radially from the widest point of the cutter head back to the cutter shaft in an arc. Preferably, the cutting edges of the cutter head extend radially outward from the distal portion of the milling cutter's rotation axis toward the proximal direction. In particular, the cutting edges of each cutter head can be formed on their edge side and shaped to move along an envelope curve, preferably essentially spherical, as the milling cutter rotates about its rotation axis (longitudinal axis). Such milling cutters may be referred to as spherical cutters and are particularly suitable for applications in which material is removed transversely / radially and / or axially / distally. In the context of the present disclosure, the cutter head may be designed so that the envelope shape described by the cutting edges of the milling cutter during rotation has other shapes, such as those of a frame cutter, a conical cutter, a cylindrical cutter, or an elliptical cutter.

[0017] According to further embodiments, the teeth or cutting edges, respectively, may be non-helical and / or non-twisted. This improves interdental space accessibility and cleaning compatibility. Furthermore, such tooth / cutting edge shapes can be manufactured relatively easily, quickly, and inexpensively.

[0018] According to a further embodiment, the milling cutter may have exactly two teeth or cutting edges arranged diametrically opposite each other on the milling cutter's rotation axis. The cutting edges are formed facing opposite each other on the two teeth, so that both cutting edges remove material when the milling cutter rotates about its rotation axis. The cutting side surface of the tooth is also called the tooth front, and the side of the tooth opposite the cutting edge is called the tooth rear. The respective clearance on the cutting side (i.e., tooth front side) represents, in the sense of the present disclosure, a chip space for the material removed by the corresponding cutting edge. Due to the described arrangement and design of the cutting edges / teeth, the space between the two teeth is particularly large, which ensures particularly good transport of the removed material and achieves rapid healing of the unconsolidated bone.

[0019] Such a two-tooth or double-edged design can be achieved particularly effectively and simply by machining the cutter head at least from the distal end of the milling cutter towards the axis of rotation on both sides (transversely) of the axis of rotation, which then forms a surface that is preferably mostly flat and forms the tooth leading portion of each tooth.

[0020] Alternatively or additionally, a step or shoulder may extend proximally from the distal portion of the rotation axis, so that the surface forming the tooth leading edge transitions to the tooth trailing edge of the opposite tooth via a step or shoulder. This step or shoulder forms a boundary between the leading edge of one tooth and the trailing edge of the tooth adjacent in the cutting direction, i.e., the tooth trailing edge of the other tooth. In a particularly advantageous embodiment for manufacturing, the step or shoulder extends from the intersection of the distal end of the cutter head with the rotation axis at an oblique angle to the rotation axis, so that the trailing (proximal) region of the cutter head does not come into contact with the shaft of the milling cutter. This angle, which is preferably in the plane of the respective leading edge and is also called the setting angle, is preferably in the range of 2° to 10°. In other words, the tooth leading edge, together with the circumferential clearance angle, forms the cutter or cutting edge. Alternatively or additionally, the tooth trailing edge may be designed with a constant width.

[0021] The tooth front is designed and / or positioned to provide a 0° rake angle at the cutting edge.

[0022] According to a further embodiment of the present disclosure, the teeth may be arranged and formed diametrically opposite one another transversely to the axis of rotation (37) without being offset in a plane. In particular, this plane also includes the axis of rotation. In particular, the teeth may be formed such that the front face of one tooth and the rear face of the other tooth together form a flat surface. The rear face of one tooth and the front face of the other tooth together form a further flat surface opposite the aforementioned surface. The two surfaces may be parallel to one another. Preferably, they are parallel to one another in a direction transverse to the axis of rotation and are inclined to one another by the angle of the tooth thickness in the direction of the axis of rotation.

[0023] A particularly advantageous embodiment of the present disclosure regarding material evacuation is characterized in that at least one cutting edge has at least one break or groove, particularly as a chip-breaking groove. This may be incorporated into the tooth, particularly in the centripetal direction. The break of the cutting edge reduces the width of the cutting edge, facilitating its penetration into the bone and improving cutting performance. The chip-breaking grooves of adjacent teeth / cutting edges may be designed and / or positioned offset from one another, particularly so that the groove of one tooth is positioned in a position corresponding to the cutting edge of the other tooth, and vice versa, so that the cutting edges of the teeth alternately participate in the removal. In this way, the size and shape of the removed chips are determined so that the transport of the removed material is optimized. Furthermore, this ensures that even if the milling cutter nominally has more cutting edges, only one cutting edge engages the area swept by each cutting edge section during rotation about the rotation axis.

[0024] The rear side of the tooth in the cutting direction, i.e., the tooth rear part, can in particular be formed and / or arranged inclined relative to the axis of rotation so that the tooth widens conically from distal to proximal towards the shaft. The tooth rear part can in particular be designed in the form of a flat surface, which is advantageous for accessibility, cleaning suitability and ease of manufacture.

[0025] In particular, the tooth thickness may increase from distal to proximal at an angle of 1° to 10° relative to the axis of rotation. This angle is called the tooth thickness angle. This results in particularly high stability and excellent cleanability. The distal thickness of the tooth or cutting edge may be between 1 / 20 and 1 / 10 of the radial diameter of the cutter head. In this way, particularly large clearances can be provided as chip spaces, while simultaneously providing high stability of the tooth / cutting edge. Furthermore, cutting performance and chatter tendency can be influenced by the appropriate design of the tooth thickness. Finally, the strength of the cutter head may be defined by the tooth thickness at the required height.

[0026] A further embodiment of the present disclosure is characterized in that the cutting edge has a constant clearance angle in the range of 2° to 30°. Alternatively, the cutting edge may have a clearance angle that varies along the path from distal to proximal, particularly in the range between 2° and 30°. The cutting edge may have a rake angle of 0°. The circumferential clearance angle forms the shape of the cutter head that defines the material removal. Cutting performance and chatter tendency can be influenced by the design of the corresponding clearance angle. As described above, by varying the clearance angle along the path, cutting performance and chatter tendency can be further influenced positively.

[0027] A particularly user-friendly embodiment is characterized in that the cutter head has a tip with an angle of 110° to 150° at its distal end, which makes centering and handling particularly good and easy during use, especially when working with milling cutter tools in the axial direction. This angle is called the tip angle. Close to the tip, the cutting edges / teeth may be arcuate, especially circular, in further paths.

[0028] According to the present disclosure, the milling cutter can be designed as either a clockwise milling cutter (right-handed cutter) or a counterclockwise milling cutter (left-handed cutter).

[0029] With regard to the method, the solution according to the present disclosure resides in a method for obtaining bone and / or cartilage material, wherein the bone and / or cartilage are machined with a tool, and the obtained bone / cartilage material is collected and, if necessary, stored and used for the growth of bone material, and wherein the machining of the bone and / or cartilage is carried out using a cutting tool, in particular a surgical milling cutter according to the present disclosure, in particular according to one claim described in the present specification and / or in the appended claims.

[0030] In summary, the present disclosure provides a surgical milling cutter that may have only two cutting edges. The interdental spaces are preferably designed so that the removed tissue is carried away as unobstructed as possible. In particular, the tooth morphology may be designed to remove all material not required for the tooth's strength. Furthermore, the surface of the milling cutter, particularly the surface of the cutter head, can be designed to be particularly smooth and flat, which favors chip evacuation. As a result of the low temperature change and particularly good chip evacuation, particularly gentle material removal can be achieved with the disclosed milling cutter, and alteration and / or damage to the removed material is largely or completely avoided. Therefore, material removed via a milling cutter according to the present disclosure is particularly well suited for artificial reconstruction of such material as part of the method according to the present disclosure.

[0031] In particular, the present disclosure provides the following advantages: -Excellent cutting performance, especially in the axial direction -Very good chip evacuation due to only two cutting edges -Reduction of temperature changes in the tissue and cutting edge - Extremely easy to clean cutter head -Symmetrical cutting edge structure -Easy to clean due to highly accessible surface -No negative rake angle -Low tendency to rattle -No tendency for interdental spaces to become clogged - Extremely quiet operation without vibrations due to masses arranged symmetrically around the axis of rotation - Low manufacturing cost due to fewer teeth / cutting edges - Easy to manufacture and inexpensive milling cutters for medical high speed applications for processing bone

[0032] Further features and advantages of the present disclosure arise from the following illustrative and non-limiting description of the figures, which are merely schematic in nature and serve only to aid in the understanding of the present disclosure. [Brief explanation of the drawings]

[0033] [Figure 1] 1 shows two perspective views of a prior art rose drill. [Figure 2] 1 shows a perspective view of a single cutter according to the prior art. [Figure 3] FIG. 2 shows a perspective partial view of a distal section of a milling cutter according to a first embodiment of the present disclosure. [Figure 4] FIG. 4 shows a side view of the milling cutter of FIG. 3. [Figure 5] 4 shows a cross-sectional view of the milling cutter of FIG. 3 in a direction transverse to the axis of rotation. [Figure 6] FIG. 4 shows a top view of the milling cutter of FIG. 3. [Figure 7] FIG. 4 shows a front view of the milling cutter of FIG. 3. [Figure 8] 4 shows a portion of the milling cutter of FIG. 3 through the axis of rotation. [Figure 9] 4 is a perspective view of the milling cutter of FIG. 3 from a different direction. [Figure 10] 4 shows a further perspective view of the milling cutter of FIG. 3 from a different direction. [Figure 11] 1A-1D show perspective views of different embodiments of milling cutters according to the present disclosure; [Figure 12] FIG. 12 shows a side view of the milling cutter of FIG. 11. [Figure 13] FIG. 12 shows a top view of the milling cutter of FIG. 11. [Figure 14] FIG. 12 shows a front view of the milling cutter of FIG. [Figure 15] 1A-1D show perspective views of different embodiments of milling cutters according to the present disclosure; [Figure 16] 16A and 16B show perspective views of the milling cutter of FIG. 15 from different directions. [Figure 17] 1A-1D show perspective views of different embodiments of milling cutters according to the present disclosure; [Figure 18] 8 is a view corresponding to FIG. 7 with markings of the chip space. [Figure 19]15 is a view corresponding to FIG. 14 with chip space markings. [Figure 20] 10 shows a top view of a further embodiment of a milling cutter according to the present disclosure; [Figure 21] 21 shows a cross-sectional view of the milling cutter of FIG. 20 in a direction transverse to the axis of rotation. [Figure 22] 22 shows a cross-sectional view of the milling cutter of FIGS. 20 and 21 as viewed from the side. FIG. [Figure 23] 23 shows an enlarged detail of FIG. 22. [Figure 24] 10 shows a side view of a further embodiment of a milling cutter according to the present disclosure. [Figure 25] 25 shows a top view of the milling cutter of FIG. 24. [Figure 26] 26 shows a front view of the milling cutter of FIGS. 24 and 25 in a direction transverse to the axis of rotation. FIG. [Figure 27] 25 shows an enlarged detail of FIG. 24. Detailed Description of the Invention

[0034] FIG. 1 shows a prior art rose drill 1 in two perspective views from different directions. It has a cutter shaft 2 on its proximal side and a cutter head 3 on its distal side, which has a generally spherical outer contour. The rose drill 1 has a longitudinal axis 4, which also serves as the axis of rotation 4 during operation. In the illustrated example, it has a total of eight teeth 5. Each tooth 5 has a cutting edge 7 on the side facing away from the axis of rotation 4, extending proximally from the distal tip 6 of the cutter head 3 toward the cutter shaft 2. Intertooth spaces 8 are formed between adjacent teeth 5. Each tooth 5 has a twist and extends helically from distal to proximal. Therefore, the teeth 5 and their cutting edges 7 can be said to converge at the distal end 9 of the cutter head at the axis of rotation 4 of the rose drill 1. The two views in FIG. 1 clearly show that the height of the teeth 5 decreases toward the distal end 9, reaching zero directly at the axis of rotation 4 or the tip 6, respectively. In other words, the depth of the interdental space is zero at the distal end 9 or distal tip 6, respectively, and increases in the proximal direction towards the cutter shaft 2. Therefore, the chip space available for the material removed during axial advancement in the direction of the longitudinal axis 4 of the milling cutter 1 is very small near the tip 6 and non-existent at the tip 6, so that the interdental space 8 can easily become clogged with the drawbacks described at the beginning.

[0035] FIG. 2 shows, in a perspective view, a further known milling cutter 10 in the form of a so-called single cutter 10. It has a cutter shaft 11 on its proximal side and a cutter head 12 on its distal side. The single cutter 10 has a longitudinal axis 13, which also serves as the axis of rotation 13 during operation. The cutter head 12 has a cutting edge 14b formed by flattening the axis of rotation 13 inserted on one side, resulting in a substantially flat front surface 15. A recessed edge 14a is formed on the opposite side of the cutting edge 14b, forming a clearance / free surface for the cutting edge 14b. The milling cutter is designed exclusively for clockwise rotation, i.e., it cuts only in clockwise rotation. Due to its design, the entire mass of the cutter head 11 is located on one side of the axis of rotation 13. As a result, the mass distribution of the single cutter 10 is asymmetric, which is related to the drawbacks described at the beginning.

[0036] Figures 3, 9 and 10 show a first embodiment of a surgical milling cutter 16 according to the present invention, with different views and cross-sections shown in Figures 4 to 8. The milling cutter 16 has a cutter shaft 17 at its proximal end and a cutter head 18 at its distal end. The milling cutter 16 has a longitudinal axis 19, which also serves as the axis of rotation 19 during operation. At its distal end 20, the cutter shaft 17 extends coaxially with the axis of rotation 19, which runs centrally through the cutter head 18 (see in particular Figure 7).

[0037] The cutter head 18 has exactly two teeth 21, 22, i.e., a first tooth 21 and a second tooth 22. The tooth 21 has a cutting edge 23 for rotationally removing tissue. The tooth 22 has a cutting edge 24 for rotationally removing tissue. The two teeth 21, 22, and therefore the cutting edges 23, 24, are disposed diametrically opposite each other across the rotation axis 19 of the milling cutter 16. The cutting edges 23, 24 are disposed on the corresponding tooth 21, 22 facing away from the rotation axis 19, and are arc-shaped. They start at the distal end 20 of the rotation axis 19 and extend first from the distal radially inward to the proximal radially outward, then further arc from the widest point 25 of the cutter head 18 toward the proximal radially inward toward the cutter shaft 17. Each of the cutting edges 23, 24 is non-helical and twist-free. This design causes the milling cutter 16 to have an essentially spherical envelope curve as it rotates about its axis of rotation 19.

[0038] The two teeth 21, 22 are identical, and the description of tooth 21 applies equally to tooth 22. As can be seen particularly well in FIG. 7 , tooth 21 has a flat leading surface 26a that forms the leading surface of tooth 21 in the direction of rotation and a flat trailing surface 27a that forms the trailing surface of tooth 21 in the direction of rotation. Tooth 22 has a flat leading surface 26b that forms the leading surface of tooth 22 in the direction of rotation and a flat trailing surface 27b that forms the trailing surface of tooth 22 in the direction of rotation. The direction of rotation is the cutting direction of milling cutter 16. Teeth 21, 22 are offset from each other transversely to the axis of rotation 19 (see FIG. 7 ) so that the leading surfaces 26a, 26b of the two teeth 21, 22 straddle a common plane in which the axis of rotation 19 lies. 7, it can be clearly seen that cutting edge 23 of first tooth 21 and cutting edge 24 of second tooth 22 meet at the tip of distal end 20, where axis of rotation 19 passes right through distal end 20. Axis of rotation 19 lies in the plane of front faces 26a and 26b.

[0039] The rear faces 27a / 27b are inclined axially relative to the front faces 26a / 26b by a longitudinal tooth angle g' between 4° and 12.5°, and the cutter head 18 has a total tooth thickness angle g between 8° and 25° (see FIG. 8). Furthermore, the rear faces 27a / 27b are inclined relative to the front faces 26a / 26b transversely to the rotation axis 19 by a transverse tooth angle a between 0° and 10° (see FIG. 7). The tooth thickness S' of the teeth 21 at the distal end 20 depends on the diameter and is approximately 1 / 10 (one tenth) of the diameter D of the cutter head 18. The tooth thickness S' of the teeth 22 at the distal end 20 also depends on the diameter and is approximately 1 / 10 (one tenth) of the diameter D of the cutter head 18. Therefore, the cutter head thickness S of the cutter head 18 is a total of approximately 2 / 10 of the diameter D (see FIG. 4). The distal end 20 of the cutter head 18 is designed as a tip with a point angle c of 90° to 150° (see FIG. 6). The cutting edges 23, 24 each extend from the tip of the distal end 20 toward the cutter shaft 17 over a clearance angle d of 110° to 170° (see FIG. 6).

[0040] A shoulder 28a with a step 28a or shoulder surface 29a is formed between the front surface 26a of tooth 21 and the rear surface 27b of tooth 22, starting from the distal end 20 at the axis of rotation 19 and extending proximally. A shoulder 28b with a step 28b or shoulder surface 29b is formed between the front surface 26b of tooth 22 and the rear surface 27a of tooth 21, starting from the distal end 20 at the axis of rotation 19 and extending proximally. The transitions from the front surfaces 26a, 26b to the shoulder surfaces 29a, 29b are rounded and disposed at a set angle f (see FIG. 6) ranging from 2° to 10°. The set angle f is oblique to the axis of rotation 19 and lies in the plane of the front surfaces 26a, 26b. The shoulder surfaces 29a, 29b are also disposed at a tooth front angle e ranging from 110° to 160° in a plane transverse to the axis of rotation 19 (see FIG. 5). The clearance angle b of each cutting edge 23, 24 is in the range of 0° to 30° and extends circumferentially, i.e. over the entire range of the clearance angle d (see FIG. 7). The transitions from the front faces 26a, 26b to the shoulder faces 29a, 29b are rounded in each case, which improves compatibility for material evacuation and cleaning.

[0041] 7 clearly shows that a chip space 30a is formed in front of the first tooth 21 in the direction of rotation as a clearance between its front face 26a and its shoulder face 29a, said chip space being available for material removed via the first tooth 21 and its cutting edge 23 of the milling cutter 16, and together with an area 31a behind the rear face 27b of the adjacent tooth 22 forms the total chip space 30a / 31a. Furthermore, a chip space 30b is formed in front of the second tooth 22 in the direction of rotation as a clearance between its front face 26b and its shoulder face 29b, said chip space being available for material removed via the second tooth 22 and its cutting edge 24 of the milling cutter 16, and together with an area 31b behind the rear face 27a of the adjacent tooth 21 forms the total chip space 30b / 31b. Figure 18 shows the view of Figure 7 without reference symbols, in which the clearances 30a, 30b, areas 31a, 31b and chip spaces 30a / 31a, 30b / 31b of both teeth 21, 22 of the milling cutter 16 are shown with corresponding hatching (chip spaces 30a, 30b: hatched marking, areas 31a, 31b: check marking). 7 also shows that the chip spaces 30a, 30b on the side facing the respective cutting edges 23, 24 of the shaft 19 extend from the cutting edges 23, 24 towards a region facing away from the cutting edges 23, 24 of the shaft 19, and that each chip space 30a, 30b is formed on the cutting side of the shaft 19 and extends at least in a distal region facing away from the respective cutting edges 23, 24 of the shaft 19. In FIGS. 3 to 10, the parts belonging to the first tooth 21 are marked with an additional a in the reference symbol, while the parts belonging to the second tooth 22 are marked with an additional b in the reference symbol. For example, the front face 26a is the front face of the first tooth, and the front face 26b is the front face of the second tooth 22.

[0042] 11-14 show a further embodiment of a milling cutter 34 according to the present disclosure. The milling cutter 34 has a cutter shaft 35 at its proximal end and a cutter head 36 at its distal end. The milling cutter 34 has a longitudinal axis 37, which is also an axis of rotation 37 during operation. The cutter shaft 35 extends coaxially with the axis of rotation 37, which passes centrally through the cutter head 36 at its distal end 38 (see particularly FIG. 11 ).

[0043] The cutter head 36 has a first tooth 39 and a second tooth 40. The tooth 39 has a cutting edge 41 for rotationally removing tissue. The tooth 40 has a cutting edge 42 for rotationally removing tissue. The two teeth 39, 40, and therefore the cutting edges 41, 42, are arranged diametrically opposite the rotation axis 37 of the milling cutter 34 in a common plane, the center of which is the rotation axis 37. The cutting edges 41, 42 are each arranged on the side of the corresponding tooth 39 or 40 facing away from the rotation axis. Each cutting edge 41, 42 is arc-shaped. They begin at the distal end 38 on the rotation axis 37 and extend first from the distal radially inward to the proximal radially outward, then continue in an arc from the widest point 43 of the cutter head 34 toward the proximal radially inward of the cutter shaft 35. Each cutting edge 41, 42 is non-helical and twist-free. This shape of the cutting edges 41 , 42 gives the milling cutter 34 an essentially spherical envelope curve when rotating about its axis of rotation 37 .

[0044] 11 and 12, the two teeth 39, 40 are identically formed in that flattenings are formed on the cutter head 36 on opposite sides of the rotation axis 37. The cutter head 36 therefore has two opposing flat surfaces 44, 45 that are parallel to each other in a direction transverse to the rotation axis 37 and inclined to each other in the direction of the rotation axis 37. The surfaces 44, 45 and the cutting edges 41, 42 are arranged and shaped relative to each other such that the surface 44 forms the front surface of the cutting edge 41 and the rear surface of the cutting edge 42, and the surface 45 forms the front surface of the cutting edge 42 and the rear surface of the cutting edge 41.

[0045] Surface 44 is inclined axially relative to surface 45 by a tooth thickness angle h between 0° and 20° (see FIG. 12). The cutter head thickness S of cutter head 34 at the tip of distal end 38 is between 0.05 mm and 1.0 mm (see FIG. 12). Distal end 38 of cutter head 36 is formed as a tip with a tip angle i between 90° and 160° (see FIG. 13). Cutting edges 41, 42 each extend from tip 43 of distal end 38 toward cutter shaft 35 over a clearance angle j between 110° and 170° (see FIG. 13). Cutter head 36 has a diameter D at its widest point. The cone length L, i.e., the extension of surfaces 44, 45 in the direction of rotation axis 37, is approximately 7 / 9D (7 / 9 of diameter D). The surfaces 44, 45 merge into the cutter shaft 35 at a radius R, which corresponds to approximately half the diameter D. The clearance angles k of the cutting edges 41, 42 are in each case in the range from 0° to 30° and are formed in the circumferential direction, i.e. over the clearance angle j (see Figures 13 and 14).

[0046] 14 clearly shows that chip space 30a is formed as a clearance in front of the first tooth 39 in the direction of rotation, said chip space being available for material removed via the first tooth 39 and its cutting edge 41 of the milling cutter 34, and forming together with the area 31a behind the adjacent tooth 40 the total chip space 30a / 31a. Furthermore, chip space 30b is formed as a clearance in front of the second tooth 40 in the direction of rotation, said chip space being available for material removed via the second tooth 40 and its cutting edge 42 of the milling cutter 34, and forming together with the area 31b behind the adjacent tooth 39 the total chip space 30b / 31b. Figure 19 shows the view of Figure 14 without reference numbers, in which the clearances 30a, 30b, areas 31a, 31b and chip spaces 30a / 31a, 30b / 31b of both teeth 39, 40 of the milling cutter 34 are marked with corresponding hatching (chip spaces 30a, 30b: hatched markings, areas 31a, 31b: check markings).

[0047] 15 and 16 show a variation of the embodiment of Figures 3 to 8 above, in which the cutting edge 23 of tooth 21 has a separation in the form of grooves 32a, 32b, and the cutting edge 24 of tooth 22 has a separation in the form of grooves 33a, 33b, 33c. Grooves 32a and 32b and grooves 33a, 33b, 33c are spaced apart from one another by portions of the cutting edge remaining between them, respectively. They also insert centripetally into the corresponding teeth 21, 22, separating the cutting edges 23, 24. The grooves 32a and 32b of the first tooth 21 are offset in the circumferential direction of the cutting edges 23, 24 relative to the grooves 33a, 33b, and 33c of the second tooth 22 so that parts are located in the grooves 32a and 32b of the first tooth 21 corresponding to the remaining cutting edges of the second tooth 22, and parts of the remaining cutting edges of the first tooth 21 are located in the grooves 33a, 33b, and 33c of the second tooth 22. This allows for particularly uniform material removal. With respect to other features, the embodiments of FIGS. 3 to 8 and FIGS. 15 and 16 are similar. It should be noted that within the scope of the present disclosure, the embodiments of FIGS. 11 to 14 may also include such grooves 32a, 32b, 33a, 33b, and 33c.

[0048] Figure 17 shows a variant of the embodiment of Figures 15 and 16, in which only one groove 32a, 33a is incorporated into each cutting edge 23, 24. This allows for particularly uniform material removal. With regard to other features, the embodiments of Figures 3 to 8 and 17 are similar. It should be noted that within the scope of the present disclosure, the embodiments of Figures 11 to 14 may also be provided with such grooves 32a, 33a.

[0049] 20, 21, 22, and 23 show a further embodiment of a milling cutter 46 according to the present disclosure, which is particularly distinct from the single cutter 10 shown in FIG. 2. The milling cutter 46 has a cutter shaft 47 on the proximal side and a cutter head 48 on the distal side. It also has a longitudinal axis 49, which is also the axis of rotation 49 during operation. The cutter head 48 is formed by two symmetrically opposite flattenings, in each case extending a short distance in front of the axis of rotation 49. The cutter head 48 has an additional pointed surface 66 at its tip 53, which extends to the axis of rotation 49 with a clearance angle m. The cutter head 48 has a cutting edge 50b, opposite which a further cutting edge 50a is formed. Both cutting edges 50a, 50b have the same shape and dimensions, in particular the same diameter, and together with the pointed surface 66 form a common front surface 51. Opposite the front surface, they together form a substantially flat rear surface 52. As shown in particular in FIGS. 21 and 22, the rear surface 52 is smaller than the front surface 51, thereby forming a clearance angle k for each of the two cutting edges 50a, 50b. The front surface forms a clearance / free surface for both cutting edges 50a, 50b. The front edge 53 of the cutter head 48, also referred to as the tip 53, is preferably also formed as a cutting edge to achieve a cutting effect in the axial direction, i.e., in the direction of the rotation axis 49. This can be achieved, for example, by having both cutting edges 50a, 50b extend exactly to the rotation axis 49. The chip spaces 54a, 54b and clearances 55a, 55b for both cutting edges 50a, 50b are shown in FIG. 21.

[0050] The milling cutter 46 is therefore designed for both clockwise and counterclockwise rotation, i.e., it cuts in both clockwise and counterclockwise rotation. Due to its shape, the mass of the cutter head 48 is minimized by the omission of sharp surfaces 66 that are asymmetric with respect to the axis of rotation 49, resulting in a very smooth operation. Furthermore, the cutter head 48 can be designed with surprisingly small dimensions, in particular with diameters smaller than, for example, 3 mm, 4 mm, or 5 mm.

[0051] FIGS. 24, 25, 26, and 27 illustrate a further embodiment of a milling cutter 56 according to the present disclosure, which is also distinct from the single cutter 10 shown in FIG. 2. The milling cutter 56 is similar to the milling cutter 46 shown in FIGS. 20 and 21 and is designed for both clockwise and counterclockwise rotation, i.e., it cuts in both clockwise and counterclockwise rotations. It has a cutter shaft 57 on its proximal side and a cutter head 58 on its distal side. It also has a longitudinal axis 59, which is also the axis of rotation during operation. The cutter head 58 is formed by two opposing flats, one of which forms a front surface 61 and the other of which forms a rear surface 62. Between the front surface 61 and the rear surface 62, a cutting edge 60b is formed on one side of the cutter head 58 and another cutting edge 60a is formed on the opposite side. The distal end of the cutter head 58 is in the form of a tip 63. A characteristic feature of the milling cutter 56 is that its front face 61 is located on the axis of rotation 59 of the tip 63. The front face 61, the cutting edges 60a, 60b, and the axis of rotation 59 can be said to intersect at the tip 63. The two cutting edges 60a, 60b have the same shape and dimensions, particularly the same diameter. As shown in FIG. 24 , the rear face 62 is smaller than the front face 61, thereby forming a clearance angle m for each of the two cutting edges 60a, 60b. The front face forms a clearance / free surface for each of the cutting edges 60a, 60b. The front edge or tip 63 of the cutter head 58 is preferably also formed as a cutting edge, so that the cutting action can be performed in the axial direction, i.e., in the direction of the axis of rotation 59. The chip spaces 64a, 64b and clearances 65a, 65b for each of the cutting edges 60a, 60b are depicted in FIG. 24.

[0052] The cutter head 58 has a cutter head thickness S at its tip 63. Starting from the tip 63, the front and rear faces 61, 62 are inclined relative to each other by a tooth thickness angle h. Also, the front face 61 is inclined relative to the axis of rotation 59 by an upper tooth thickness angle n, and the rear face 62 is inclined relative to the axis of rotation 59 by a lower tooth thickness angle o, where the relationship h=n+o applies.

[0053] Due to its shape, the milling cutter 56 has a somewhat less favorable mass distribution in terms of eccentricity than the milling cutter 46 shown in Figures 20 and 21, but has better cutting edge characteristics in the direction of the axis of rotation 59. The cutter head 58 can also be made with surprisingly small dimensions, in particular with diameters smaller than, for example, 3 mm, 4 mm or 5 mm. The following items are elements that are included in the claims of the international application: (Item 1) A surgical milling cutter (16, 34, 46, 56) comprising: a shaft (17, 35, 47, 57) for rotary drive connection to a drive unit about an axis of rotation (19, 37, 49, 59) extending longitudinally of the shaft (17, 35, 47, 57); a cutter head (18, 36, 48, 58) disposed distally of the shaft (17, 35, 47, 57); the cutter head (18, 36, 48, 58) has at least two teeth (21, 22, 39, 40) with respective cutting edges (23, 24, 41, 42, 50a, 50b, 60a, 60b) for rotationally removing tissue; the cutting edges (23, 24, 41, 42, 50a, 50b, 60a, 60b) are designed for tissue removal in both the distal and transverse directions, respectively; The chip spaces (30a, 30b, 54a, 54b) are formed as clearances in each case between adjacent teeth (21, 22, 39, 40) in the circumferential direction, 1. A surgical milling cutter, comprising: a cutting edge space extending laterally of the axis of rotation facing the respective cutting edge, the cutting edge space extending laterally of the axis of rotation facing away from ... (Item 2) Item 1. The surgical milling cutter (16, 34, 46, 56) according to item 1, characterized in that the cutting edges (23, 24, 41, 42, 50a, 50b, 60a, 60b) are each arcuate from a distal radially inner side to a proximal radially outer side and / or are each non-helical and twist-free. (Item 3) 3. The surgical milling cutter (16, 34, 46, 56) according to item 1 or 2, characterized in that the milling cutter (16, 34, 46, 56) has exactly two teeth (21, 22, 39, 40) arranged diametrically opposite the rotation axis (19, 37, 49, 59) of the milling cutter (16, 34, 46, 56). (Item 4) 4. The surgical milling cutter (16, 34) according to any one of items 1 to 3, characterized in that the teeth (21, 22, 39, 40) are offset from one another in a direction transverse to the axis of rotation (19, 37), in particular so that front faces (26a, 26b, 44, 45) of the teeth (21, 22, 39, 40) straddle a common plane in which the axis of rotation (19, 37) lies. (Item 5) 5. The surgical milling cutter (16, 34, 46, 56) according to any one of items 1 to 4, characterized in that the front faces (26a, 26b, 44, 45, 51) of the teeth (21, 22, 39, 40) in the cutting direction are substantially flat and / or stepped (28a, 28b) starting from the distal part of the axis of rotation (19, 37) and extending in the proximal direction, and are arranged at a setting angle (f) of 2° to 10° in the plane of the front faces (26a, 26b) relative to the axis of rotation (19, 37). (Item 6) 4. A surgical milling cutter (16, 34, 46, 56) according to any one of items 1 to 3, characterized in that the teeth (21, 22, 39, 40) are located diametrically opposite each other without offset transversely to the axis of rotation (37), in particular so that the front face (26 a) of one tooth (39) and the rear face (27 b) of the other tooth (40) together form a flat surface (44), and the rear face (27 a) of one tooth (39) and the front face (26 b) of the other tooth (40) together form a flat surface (45). (Item 7) 7. The surgical milling cutter (16, 34, 46, 56) according to any one of items 1 to 6, characterized in that at least one of the cutting edges (23, 24, 41, 42) has at least one break (32a, 32b, 33a, 33b, 33c) or groove (32a, 32b, 33a, 33b, 33c), which break or groove is integrated into the tooth (21, 22, 39, 40) in a centripetal direction, reducing the length of the cutting edge and thereby reducing the feed force. (Item 8) 8. The surgical milling cutter (16, 34, 46, 56) according to any one of items 1 to 7, characterized in that the thickness of the teeth (21, 22, 39, 40) increases from distal to proximal with a tooth thickness angle (g, h) of 1° to 10° relative to the axis of rotation (19, 37). (Item 9) 9. The surgical milling cutter (16, 34, 46, 56) according to any one of items 1 to 8, characterized in that the distal thickness of the teeth (21, 22, 39, 40) is between 1 / 20 and 1 / 10 of the diameter (D) of the cutter head (18, 36) in the radial direction. (Item 10) 10. The surgical milling cutter (16, 34, 46, 56) according to any one of items 1 to 9, characterized in that the cutting edges (23, 24, 41, 42) have a constant clearance angle (b, k) of 2° to 30° along the cutting edges (23, 24, 41, 42), or the cutting edges (23, 24, 41, 42) have clearance angles (b, k) in the range of 2° to 30° and which vary along the path of the cutting edges (23, 24, 41, 42). (Item 11) 11. The surgical milling cutter (16) according to any one of claims 1 to 10, characterized in that the cutting edges (23, 24) have a rake angle of 0°. (Item 12) 12. A surgical milling cutter (16, 34, 46, 56) according to any one of items 1 to 11, characterized in that the cutter head (18, 36) has at its distal end (20, 38) a tip with a tip angle (c, i) of 110° to 150°. (Item 13) 13. The surgical milling cutter (16, 34) according to any one of items 1 to 12, characterized in that the surgical milling cutter is rotationally symmetrical with respect to the axis of rotation (19, 37). (Item 14) The surgical milling cutter comprises: a first cutting edge (50a, 60a) that provides tissue removal in a first rotational direction; 14. The surgical milling cutter (46, 56) according to any one of items 1 to 13, characterized in that it has a second cutting edge (50b, 60b) that provides tissue removal in a second rotational direction opposite to the first rotational direction. (Item 15) 15. The surgical milling cutter (16, 34, 46, 56) according to any one of items 1 to 14, characterized in that the cutter head (18, 36, 48, 58) has a frame-shaped, conical, olive-shaped or roller-shaped cross-sectional shape in a cross section passing through the rotation axis (19, 37, 49, 59). (Item 16) 1. A method for obtaining bone and / or cartilage material, comprising machining bone and / or cartilage with a tool and collecting the obtained bone and / or cartilage material, optionally storing it and using it for growing bone material, characterized in that the machining of the bone and / or cartilage is carried out with a cutting tool, in particular with the surgical milling cutter (16, 34, 46, 56) according to any one of items 1 to 15. [Explanation of symbols]

[0054] 1: Rose Drill 2: Cutter shaft 3: Cutter head 4: Longitudinal axis, rotation axis 5: Teeth 6: Distal tip 7:Cutting edge 8: Interdental space 9: Distal end 10: Single cutter 11: Cutter shaft 12: Cutter head 13: Longitudinal axis, rotation axis 14a: Concave edge 14b: Clockwise rotation cutting edge 15:Front 16: Milling cutter 17: Cutter shaft 18: Cutter head 19: Longitudinal axis 20: Distal end 21: First tooth 22: Second tooth 23:Cutting edge 24:Cutting edge 25: Widest point 26a: Front of first tooth 21, 39 26b: Front surface of second tooth 22, 40 27a: Rear surface of first teeth 21, 39 27b: rear surface of second tooth 22, 40 28a: Step / shoulder of first teeth 21 and 39 28b: Step / shoulder of second tooth 22, 40 29a: Shoulder surface of first tooth 21, 39 29b: Shoulder surface of second tooth 22, 40 30a: Chip space of first teeth 21, 39 30b: chip space of first teeth 22, 40 31a, 31b: Clearance behind the rear 32a, 32b: Groove 33a, 33b, 33c: groove 34: Milling cutter 35: Cutter shaft 36: Cutter head 37: Longitudinal axis 38: Distal end 39: First tooth 40: Second tooth 41:Cutting edge 42:Cutting edge 43: Widest point 44: Surface 45: Surface 46: Milling cutter 47: Cutter shaft 48: Cutter head 49: Longitudinal axis 50a, 50b: cutting edge 51:Front 52: Rear 53: Front end, tip 54a, 54b: Chip space 55a, 55b: Clearance 56: Milling cutter 57: Cutter shaft 58: Cutter head 59: Longitudinal axis 60a, 60b: cutting edge 61:Front 62: Rear 63: Front end, tip 64a, 64b: Chip space 65a, 65b: Clearance 66: Point thinning a: Transverse tooth angle b: Clearance angle c: Tip angle d: Clearance angle e: Frontal angle of the tooth f: Setting angle g: Tooth thickness angle g´: longitudinal tooth angle h: Tooth thickness angle i: Tip angle j: clearance angle k: clearance angle L: length of the cone m: Thinning angle n: Upper tooth thickness angle o: Lower tooth thickness angle D: Diameter R: angle S: Cutter head thickness S´: Tooth thickness

Claims

1. 1. A surgical milling cutter, comprising: a shaft for rotary driving connection to a drive unit about an axis of rotation extending longitudinally of the shaft; a cutter head disposed distally of the shaft, the cutter head has two teeth with respective cutting edges for rotationally removing tissue; the cutting edges are designed for tissue removal in both a distal and a transverse direction, respectively; The chip spaces are formed as clearances in each case between adjacent teeth in the circumferential direction, the teeth or cutting edges are non-helical and twist-free; each chip space on the side of the axis of rotation facing the respective cutting edge extends from the cutting edge to a region on the side of the axis of rotation away from the cutting edge; the teeth are diametrically opposed and not offset from one another in a direction transverse to the axis of rotation; The two teeth are positioned such that a front surface of one tooth and a rear surface of the other tooth together form a single flat surface, and a rear surface of one tooth and a front surface of the other tooth together form a single flat surface, the cutting edge is arc-shaped and extends from a distal radially inner side to a proximal radially outer side to form the widest portion of the cutter head, forming an arc from the distal direction to the proximal radially inner side in the direction of the shaft; Surgical milling cutter.

2. 2. The surgical milling cutter according to claim 1, wherein the front surfaces of the teeth in the cutting direction are substantially flat and / or stepped, starting from a distal portion of the rotation axis and extending in a proximal direction, and are arranged at a set angle of 2° to 10° in the plane of the front surfaces relative to the rotation axis.

3. 2. The surgical milling cutter of claim 1, wherein at least one of the cutting edges has at least one break or groove, the break or groove being integrated into the tooth in a centripetal direction to reduce the length of the cutting edge, thereby reducing the feed force.

4. 2. The surgical milling cutter of claim 1, wherein the tooth thickness increases from distal to proximal with a tooth thickness angle of 1 to 10 degrees relative to the axis of rotation.

5. 2. The surgical milling cutter of claim 1, wherein the distal thickness of the teeth is between 1 / 20 and 1 / 10 of the diameter of the cutter head in the radial direction.

6. 2. The surgical milling cutter of claim 1, wherein the cutting edge has a constant clearance angle of 2° to 30° along the cutting edge, or the cutting edge has a clearance angle that varies along the path of the cutting edge, the clearance angle being in the range of 2° to 30°.

7. 2. The surgical milling cutter of claim 1, wherein the cutting edge has a 0° rake angle.

8. 2. The surgical milling cutter of claim 1, wherein the cutter head has a tip at its distal end with a tip angle of 110° to 150°.

9. 2. The surgical milling cutter of claim 1, wherein the surgical milling cutter is rotationally symmetrical about the axis of rotation.

10. The surgical milling cutter comprises: a first cutting edge that provides tissue removal in a first rotational direction; 10. The surgical milling cutter of claim 1, further comprising a second cutting edge for effecting tissue removal in a second rotational direction opposite the first rotational direction.

11. 2. The surgical milling cutter according to claim 1, wherein the cutter head has a cross-sectional shape that is frame-shaped, conical, olive-shaped, or roller-shaped in a cross section passing through the rotation axis.

Images