Surgical tool which can be rotated about a longitudinal axis

Abstract

The invention relates to a surgical tool (2), in particular a milling tool, for a surgical instrument, said tool being rotatable about a longitudinal axis (4) and having a tool shaft (6) and a material-removing working head (8) at the free end of the tool shaft (6), wherein material-removing cutting edges (12) with a defined geometry are formed in a working head (8) pole region (10) facing away from the tool shaft (6) for machining purposes, and material-removing structures (16) for a non-machining grinding or abrading machining process are formed in a circumferential region (14) of the working head (8) outside the pole region (10).

Description

[0001] Surgical tool that can be driven to rotate around a longitudinal axis

[0002] The invention relates to a surgical tool, in particular a milling tool, for a surgical instrument that can be driven in rotation about a longitudinal axis. It comprises a tool shaft and a material-removing working head at the free end of the tool shaft. Furthermore, the invention relates to a surgical instrument with a handpiece and a tool that is releasably held in the handpiece and can be driven in rotation.

[0003] The invention therefore relates to tools which are operated at high rotational speeds of in particular up to 100,000 revolutions per minute, in particular from 10,000 to 100,000 revolutions per minute.

[0004] Previously known tools have a working head with a rotationally symmetrical, mostly spherical basic geometry.

[0005] To date, milling tools have either only cutting edges with a defined geometry for metal-cutting operations or only material-removing structures with an undefined geometry for non-metal-cutting grinding or abrasive operations. Milling cutters with cutting edges with a defined geometry can be used for their intended purpose, achieving greater material removal, i.e., higher stock removal rates, than cutters with only grinding or abrasive structures. However, they tend to run unevenly and "chatter" during operation. Examples of milling tools of the first type are so-called rose cutters, conical cutters, or cylindrical cutters. Examples of milling tools of the second type are so-called diamond cutters, which have diamond grains on the surface of the working head.Based on this, the present invention is based on the object of creating a surgical tool of the type mentioned above which is versatile in use and is able to ensure quiet operating behavior while still providing sufficient cutting performance.

[0006] This object is achieved according to the invention in a tool of the type mentioned at the outset in that material-removing cutting edges with a defined geometry for machining are formed in a pole region of the working head facing away from the tool shank and that material-removing structures for non-machining grinding or sanding are formed in a peripheral region of the working head outside the pole region.

[0007] By means of material-removing cutting edges with a defined geometry in the pole area of ​​the tool head, a high material removal rate can be achieved, i.e. high performance during axial plunging of the tool. Because the cutting edges with a defined geometry do not extend over the circumference, unfavorable chattering behavior during operation, which impairs precise and safe work, can be avoided or at least significantly reduced. In terms of smooth running, it is advantageous that grinding or abrasive structures with typically undefined geometries are used when the tool is axially plunging in the circumferential area outside the pole area. These structures prove to be gentler on the tissue and less traumatic. Grinding or abrasive machining by these structures also does not lead to unpleasant chattering of the tool and instrument.The inventive surface design of the tool's working head, namely with cutting edges of a defined geometry in the pole area and with material-removing grinding or abrasive structures outside the pole area, expands and improves the applicability and operating behavior of the tool. In particular, this enables axial machining with sufficient performance while simultaneously protecting the tissue surrounding the created recess.

[0008] It is conceivable that the material-removing cutting edges with a defined geometry are formed integrally with the working head or attached to the working head. These cutting edges with a defined geometry are cutting structures with typical cutting geometry.

[0009] It also proves advantageous if the material-removing cutting edges with a defined geometry are arranged in a star shape, viewed along the longitudinal axis. This creates radially outward-expanding spaces between the cutting edges, in which removed chips are initially collected and then transported radially outward.

[0010] It is also conceivable and advantageous if the material-removing cutting edges with a defined geometry taper radially outwards when viewed in the direction of the longitudinal axis.

[0011] Furthermore, it proves to be advantageous if the material-removing cutting edges with a defined geometry have a greatest elevation relative to a base area of ​​the working head at the pole of the working head, which is preferably located on the longitudinal axis.

[0012] It is also conceivable for the elevation of the material-removing cutting edges with a defined geometry to decrease radially outward relative to the base area of ​​the working head. Viewed orthogonally to the longitudinal direction, this creates an approximately conical or wedge-shaped shape in the pole area, formed by the respective cutting edges. According to one embodiment of the cutting edge geometry, it is proposed that one of the material-removing cutting edges with a defined geometry forms a transition cutting edge whose cutting edge extends continuously, in particular steadily, across the pole of the pole area.

[0013] With regard to the dimension of the pole area where cutting edges with a defined geometry are provided, it proves to be advantageous if the pole area, in the front view of the working head, extends in the direction of the longitudinal axis starting from a pole lying on the longitudinal axis up to a maximum of 80%, in particular up to a maximum of 75%, in particular up to a maximum of 70%, in particular up to a maximum of 65%, and further in particular up to a maximum of 60% of a largest dimension (R) of the working head orthogonal to the longitudinal axis radially outwards.

[0014] The material-removing structures provided outside the pole area and possibly extending into the pole area are designed for non-cutting grinding or abrasive processing of grain structures with undefined geometry.

[0015] It is conceivable that the material-removing structures for non-cutting grinding or sanding processing are formed integrally with the working head or are attached to the working head.

[0016] In particular, it is proposed that the material-removing structures for non-machining grinding or sanding comprise abrasive grains or be formed from abrasive grains. In particular, these abrasive grains can comprise diamond.

[0017] If the material of the working head is made of a sufficiently stable and abrasive material or is coated with such a material, it is generally conceivable to roughen the surface of the working head in such a way, for example by blasting this surface, that material-removing structures are formed for grinding or sanding processing.

[0018] The invention also relates to a surgical instrument having the features of claim 13.

[0019] Further details, advantages and features of the invention emerge from the appended patent claims and from the drawing and subsequent description of a preferred embodiment of the tool according to the invention.

[0020] The drawing shows:

[0021] Figure 1 is a side view of a tool according to the invention with the tool shank only partially shown; and

[0022] Figure 2 is a front view of the tool according to Figure 1.

[0023] Figures 1 and 2 show a surgical tool 2, for example in the form of a milling tool, for a surgical instrument (not shown) that can be driven to rotate about a longitudinal axis 4. The tool 2 comprises a tool shaft 6 and a material-removing working head 8 at the free end of the tool shaft 6.

[0024] In a pole region 10 of the working head 8 facing away from the tool shank 6, material-removing cutting edges 12 with a defined geometry for machining are formed. In a peripheral region 14 of the working head 8 outside the pole region 10, material-removing structures 16 are formed for non-machining grinding or sanding machining.

[0025] It can be seen from the figures that the material-removing cutting edges 12 with a defined geometry extend only in the pole region 10, with the longitudinal axis 4 penetrating the pole region 10 centrally at the pole 18. When the tool 2 is immersed in a bone while rotating in the direction of the longitudinal axis 4 during operation of the surgical instrument, the tool 2 first comes into contact with the bone to be machined with its pole region 10 and the cutting edges 12 with a defined geometry provided there. Since the cutting edges 12, due to their cutting edge geometry, demonstrate high cutting performance when the tool is rotated at high speeds, the tool 2 can penetrate the bone quickly. As can also be seen from the figures, the cutting edges 12, which are arranged in a star shape here as an example, extend approximately radially outwards with a slightly arcuate curvature. They taper radially outwards.They have a greatest elevation or height relative to a base surface 20 of the working head 8 at the pole 18, where the longitudinal axis 4, in its geometric extension, pierces the pole region 10. Towards the radial outside, this elevation of the cutting edges 12 relative to the base surface 20 decreases, ultimately reaching zero, so that outside the pole region 10, no cutting edges 12 with a defined geometry are provided on the working head 8. This leads to smoother running of the tool. In the case shown purely as an example, Figure 2 shows a so-called transition cutting edge 22 that extends diametrically across the pole 18, with the remaining cutting edges 12 converging inwards at two points on either side of the transition cutting edge 22. This geometry enables better guidance of the tool 2 when plunging into the material to be machined.

[0026] In the tool 2 shown as an example, the pole region 10 is dimensioned such that, viewed from the front of the working head 8, it extends in the direction of the longitudinal axis 4, i.e., viewed as in Figure 2, starting from the pole 18 to approximately 2 / 3 or 66% of a largest dimension (R) of the working head 8 orthogonal to the longitudinal axis 4.

[0027] Adjacent to the pole region 10 of the working head 8 is the peripheral region 14 of the working head 8, in which only material-removing structures 16 are provided for non-machining, grinding, or abrasive machining. These structures do not have cutting edges with a defined cutting geometry, but rather form a more or less rough surface structure 16, which leads to abrasion in grinding contact with a material to be machined, such as bone material in particular. The apparently regular arrangement of the material-removing structures 16 in the figures is to be understood purely as an example and schematic. In particular, the material-removing structures 16 for non-machining, grinding, or abrasive machining can also be arranged and formed completely irregularly, for example by mechanically blasting a surface of the working head 8, i.e., by being formed, so to speak, in one piece from the material of the working head 8.As explained at the beginning, it would also be conceivable for the working head 8 to be coated with material-removing structures, in particular granular structures, in particular abrasive grains, wherein an adhesion-promoting material embedding the material-removing structures or grains can also be used for this purpose.

Claims

Patent claims 1. Surgical tool (2), in particular a milling tool, for a surgical instrument, which can be driven in rotation about a longitudinal axis (4), having a tool shaft (6) and having a material-removing working head (8) at the free end of the tool shaft (6), characterized in that material-removing cutting edges (12) with a defined geometry for cutting operations are formed in a pole region (10) of the working head (8) facing away from the tool shaft (6), and that material-removing structures (16) for non-cutting grinding or sanding operations are formed in a peripheral region (14) of the working head (8) outside the pole region (10).

2. Surgical tool (2) according to claim 1, characterized in that the material-removing cutting edges (12) with a defined geometry are formed integrally with the working head (8) or are attached to the working head (8).

3. Surgical tool (2) according to claim 1 or 2, characterized in that the material-removing cutting edges (12) are arranged in a star shape with a defined geometry viewed in the direction of the longitudinal axis (4).

4. Surgical tool (2) according to claim 1, 2 or 3, characterized in that the material-removing cutting edges (12) with a defined geometry taper radially outwards when viewed in the direction of the longitudinal axis (4).

5. Surgical tool (2) according to one or more of the preceding claims, characterized in that the material-removing cutting edges (12) with a defined geometry have a greatest elevation relative to a base surface (20) of the working head at the pole (18) of the working head (8), which preferably lies on the longitudinal axis (4).

6. Surgical tool (2) according to one or more of the preceding claims, characterized in that an elevation of the material-removing cutting edges (12) with a defined geometry decreases radially outwards compared to a base surface (20) of the working head (8).

7. Surgical tool (2) according to one or more of the preceding claims, characterized in that one of the material-removing cutting edges (12) with a defined geometry forms a transition cutting edge (22), the cutting edge of which extends continuously, in particular continuously, in particular over the pole (18) of the pole region (10).

8. Surgical tool (2) according to one or more of the preceding claims, characterized in that the pole region (10), viewed in the frontal view of the working head (8) in the direction of the longitudinal axis (4), extends radially outwards from a pole (18) lying on the longitudinal axis (4) up to a maximum of 80%, in particular up to a maximum of 75%, in particular up to a maximum of 70%, in particular up to a maximum of 65%, and further in particular up to a maximum of 60% of a largest dimension (R) of the working head (8) orthogonal to the longitudinal axis (4).

9. Surgical tool (2) according to one or more of the preceding claims, characterized in that the material-removing structures (16) are formed for a non-machining grinding or sanding processing of grain structures with undefined geometry.

10. Surgical tool (2) according to one or more of the preceding claims, characterized in that the material-removing structures (16) for non-machining grinding or sanding processing are formed integrally with the working head (8) or are attached to the working head (8).

11. Surgical tool (2) according to one or more of the preceding claims, characterized in that the material-removing structures (16) for non-machining grinding or sanding processing comprise abrasive grains or are formed by abrasive grains.

12. Surgical tool (2) according to claim 11, characterized in that the abrasive grains comprise diamond.

13. Surgical instrument, with a handpiece and with a tool (2) detachably held in the handpiece and capable of rotation, in particular a milling tool, according to one or more of the preceding claims, wherein the handpiece delimits a tool receiving opening extending in a longitudinal direction, and wherein the tool (2) with its tool shank (6) can be inserted into the tool receiving opening of the handpiece in the longitudinal direction and can be fixed there in a rotationally fixed manner.

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