Bone screw

Abstract

Bone screw, in particular of the self-drilling screw type, comprising a screw head, a threaded section and a tip section having or forming a cutting blade, wherein the threaded section has, at least in one partial area, a surface roughness that differs from the surface roughness of the tip section.

Description

[0001] Bone screw

[0002] Description

[0003] Background of the Revelation

[0004] The present disclosure relates to a bone screw according to the preamble of claim 1, and in particular to a surgical bone screw with a centrally roughened surface in the threaded area, for example, for fixing an anterior cervical plate to the spine. Preferably, the threaded area is only partially roughened, i.e., the tip or tip section of the screw is not roughened or is smooth (with respect to the roughened area) to prevent blunting. More preferably, the roughened area may not be provided completely around the screw, for example, for manufacturing reasons, but may be limited to (certain) partial sections or sectors of the screw threaded area. The roughening of the screw serves to improve anchorage in the bone, particularly with regard to screw migration out of the bone.

[0005] State of the art

[0006] Bone screws, particularly self-tapping surgical bone screws for fixing implants such as anterior cervical plates, are known from the prior art. These screws already have roughened surfaces to ensure better anchorage in the bone, thereby reducing screw migration and preventing loosening, due in part to the increased frictional resistance of the screw within the bone. For this purpose, the surface of the bone screws undergoes a further (surface) treatment after a basic shaping process. Pre-drilling is recommended as an additional assembly step for such known bone screws.

[0007] Brief description of the disclosure: The object of the present disclosure is to provide a surgical bone screw that ensures a secure hold in a bone and yet can be easily screwed into the bone. Preferably, the bone screw should enable a medical application, in particular as a permanent or temporary implant, which is preferably self-drilling, which achieves sufficient anchorage in the bone, in particular for fixing an anterior cervical plate to vertebral bodies of the spine, which achieves low migration of the bone screw in the bone or which prevents the bone screw from loosening from the bone, and which has a comparatively low screw-in resistance.Furthermore, the bone screw should preferably be easy and inexpensive to manufacture in a few production steps, be easy to handle and have a high level of application safety.

[0008] This problem(s) is / are solved according to the disclosure by a bone screw according to claim 1. Advantageous embodiments of the present disclosure are the subject of dependent claims and / or are disclosed in the following description and / or the figures.

[0009] The core concept of the invention for solving the aforementioned problems is, in principle, to design a distal tip section of the bone screw with a smooth surface and to roughen only at least a portion of the threaded section of the bone screw that adjoins the tip section proximally (compared to the tip section). In this way, a sufficiently high holding force can be achieved through the roughening, while still ensuring easy insertion of the screw into the bone due to the comparatively smooth tip surface (compared to the threaded section).

[0010] The present disclosure relates more specifically to a bone screw, in particular a self-drilling screw type, comprising a screw head, a threaded section, and a tip section. The tip section preferably has or forms a cutting edge. The threaded section has, at least in one or more regions, preferably spaced apart circumferentially or axially, a surface roughness that differs from the surface roughness of the tip section.

[0011] In other words, a bone screw is a surgical screw preferably for direct insertion into a bone without pre-drilling.

[0012] The screw head forms the proximal end to one side of the bone screw, while the tip section forms the distal end to the opposite side of the screw.

[0013] The tip section is at least partially conical and has a point, a rounded end, or a flattened end. That is, the tip section is not limited to the part of the bone screw that is conical.

[0014] The tip section preferably has or forms a thin, needle-like end from the distal end with threads extending as far as possible towards the tip, wedge-shaped recesses and several cutting edges.

[0015] The threaded section is formed between the screw head and the tip section and has an external thread, at least partially, preferably completely, designed to be screwed into the bone. Optionally, a shaft section without a thread may be located between the screw head and the threaded section or the bone thread.

[0016] The tip section preferably has at least one cutting edge, which is a surface with a cutting edge, allowing the screw to easily penetrate the bone and engage early. Self-drilling screws are well known in the prior art, so reference can be made to them here. If the tip section has at least one cutting edge, then at least that section of the bone screw on which the at least one cutting edge is formed is to be considered the tip section. In other words, the tip section extends at least far enough towards the screw head that the at least one cutting edge, if present, lies completely within the tip section (the tip section can even be longer than the cutting edge(s)). Thus, the surface roughness of at least the section of the bone screw on which the cutting edge lies (i.e.,The surface roughness of at least the tip section (of the screw) differs from that of at least the portion of the threaded section. This allows the at least one cutting edge to be designed in such a way as to facilitate the insertion of the bone screw into the bone, preferably by being smooth and sharp-edged, while the portion of the threaded section ensures a sufficiently high holding force of the bone screw in the bone, preferably by being roughened.

[0017] The roughened portion of the threaded section preferably extends over at least a portion of the surface of the threaded section or over the entire surface of the threaded section. If there are multiple portions, they together extend over a portion of the surface of the threaded section or over the entire surface of the threaded section.

[0018] The surface roughness is preferably changeable, preferably adjustable, by means of surface treatment, a surface structure, a processing condition, a coating or similar.

[0019] The surface roughness in a (roughened) sub-area is preferably constant over the entire sub-area or varies within the sub-area. If the surface roughness is not constant over the entire sub-area, i.e., the surface roughness differs at various locations within the sub-area, then, within the scope of this disclosure, the surface roughness in the sub-area is understood to be the average surface roughness over the sub-area. In other words, in the case of varying surface roughness within the sub-area, the average surface roughness of the at least one sub-area differs from the average surface roughness of the tip section.

[0020] The differing surface roughness of the thread section and the tip section allows for a choice of surface roughness for the tip section that is tailored / adjusted for screwing / pre-drilling / displacing the bone when screwing the bone screw into the bone, while the surface roughness of the thread section is tailored / adjusted for anchoring the bone screw in the bone and preventing migration of the bone screw or loosening of the bone screw from the bone.

[0021] In other words, the differing surface roughness of the thread section and the tip section allows for a functional separation between the thread section and the tip section.

[0022] The present disclosure therefore offers the following setting options:

[0023] • Selection of the number of roughened thread areas,

[0024] • Selection of the axial length of the roughened thread areas and / or the extent of the roughened thread areas in the circumferential direction of the thread section,

[0025] • (If necessary, individual) selection of the surface roughness of the respective roughened thread areas compared to the smooth areas and / or (if necessary, individual) selection of the change in surface roughness within a roughened thread area,

[0026] • Selection of the axial length of the screw tip section,

[0027] • Selection of the surface finish of the tip section and / or the smooth areas in the thread section.

[0028] The screw head can have a screw engagement profile for a screw-in tool, such as an internal Torx drive. The screw head can be conical, spherical, or preferably lenticular. Furthermore, the screw head can have a screw head thread, at least in some sections.

[0029] The at least one cutting blade is preferably formed by a recess / recess / cut in the tip section.

[0030] The tip section preferably has, at least partially, at least one threaded section, which preferably represents a partial thread and is preferably interrupted by at least one recess / recess / cut in the tip section.

[0031] Preferably, the surface roughness in at least one sub-area can be higher than in the tip section.

[0032] In other words, the surface in at least one part of the thread section may be rougher than the surface in the tip section.

[0033] Surface roughness describes in particular a shape deviation of the third to fifth order and can be quantified, for example, via the mean roughness value Ra, the quadratic roughness Rq, the mean roughness depth Rz, the maximum roughness depth Rt or Rmax, the mean smoothing depth Rp and / or the depth of the largest profile valley Rv or a combination of these roughness values.

[0034] The surface roughness can be isotropic. This allows the bone screw to exhibit a sufficiently high holding force to absorb (alternating) loads in all directions and around all axes. Furthermore, this reduces stress concentrations, thereby increasing the bone screw's load-bearing capacity under continuous loads.

[0035] The anchoring of the bone screw in the bone, as well as its migration or loosening, depends on the surface roughness of the threaded section. The greater the surface roughness of the threaded section, i.e., the rougher the threaded section, the better the anchoring of the bone screw in the bone and the lower the risk of the bone screw migrating or loosening from the bone. The insertion resistance when screwing the bone screw into the bone depends primarily on the shape of the tip. The sharper the tip and, if present, the more cutting edges it has, the lower the insertion resistance, as grinding of the bone is prevented.By roughening the surface in at least one part of the thread section, but not the tip section, the bone screw can have both good anchorage and low screw-in resistance.

[0036] According to a further advantageous aspect of the present disclosure, the surface roughness in the at least one sub-area can be provided by surface treatment in the micro range.

[0037] In other words, microscopic surface properties resulting from surface processing such as grinding, blasting, or similar processes can determine the surface roughness in at least one sub-area.

[0038] Micro-level surface finishing can be carried out cost-effectively after the forming process. In particular, high average roughness values ​​(Ra) can be achieved.

[0039] According to a further advantageous aspect of the present disclosure, the at least one sub-area can extend at least partially over the thread root, thread flank, and tooth flank of the threaded section of the bone screw. In particular, the at least one sub-area can extend completely over the thread root, thread flank, and tooth flank of the threaded section of the bone screw.

[0040] In other words, the at least one sub-area can extend at least along a portion of the circumference of the bone screw, encompassing the thread valley, thread flank, and outer flank of the threaded section. The at least one sub-area can, in particular, extend along the entire circumference of the bone screw.

[0041] In other words, at least one sub-area can represent a section of the thread's lateral surface or the entire lateral surface of the thread section.

[0042] The extension of at least one sub-area across the thread root, thread flank, and tooth flank of the thread section results in a large relative surface area of ​​that sub-area compared to the total surface area of ​​the thread section. Furthermore, the extension of at least one sub-area across the entire bone screw results in a large relative surface area of ​​that sub-area compared to the total surface area of ​​the thread section.

[0043] The roughened sections are preferably relatively large in relation to the total surface area of ​​the threaded section. A relatively large surface area of ​​at least one section ensures good anchorage of the bone screw in the bone and minimizes migration of the bone screw out of the bone, or prevents the bone screw from loosening from the bone.

[0044] According to a further advantageous aspect of the present disclosure, at least two sub-areas can be provided. Preferably, the at least two sub-areas can be spaced apart from each other in the circumferential direction.

[0045] In other words, the thread section can have a surface roughness in at least two or more sub-areas that differs from the surface roughness of the tip section. These two or more sub-areas can be spaced apart from each other in the circumferential direction.

[0046] The at least two sub-sections can be provided / manufactured independently of each other. Preferably, rotation of the bone screw during the provision / manufacturing of the at least two sub-sections can be avoided.

[0047] According to a further advantageous aspect of the present disclosure, the threaded section can have a surface roughness in at least one partial circumferential region located between the at least two partial regions that differs from the surface roughness in the at least two partial regions. Preferably, the surface roughness in the at least one partial circumferential region can be the same as the surface roughness of the pointed section. In other words, a region extending over a portion of the circumference of the bone screw can have a different surface roughness than the at least two partial regions.

[0048] This allows at least one partial circumference area to remain unprocessed after the shaping process. A complete provision / production of the surface roughness of at least two partial areas is not required.

[0049] Preferably, the surface roughness can be lower in at least one partial circumferential area.

[0050] Preferably, the at least one partial perimeter area can be bordered / enclosed / delimited, at least section by section, by the at least two sub-areas.

[0051] In other words, at least one partial scope area can border at least two sub-areas, at least section by section.

[0052] According to a further advantageous aspect of the present disclosure, two circumferentially spaced sub-regions can be provided, wherein the two sub-regions can be formed on opposite sides of a median plane of the bone screw in which a rotation axis of the bone screw lies.

[0053] Preferably, the two sub-sections can extend along the axis of rotation of the bone screw. In particular, the two sub-sections can extend over more than 50, 60, 70, 80, 90, or 95% of the total length of the threaded section or over the entire length of the threaded section.

[0054] In other words, the median plane can be any plane of the bone screw or threaded section in which the axis of rotation of the bone screw or threaded section lies, with one of the two sub-areas lying on either side. Preferably, the two sub-areas can extend longitudinally along the bone screw, and in particular, completely along the longitudinal direction of the threaded section. This would allow the two sub-areas to be provided / manufactured from two opposite sides without requiring rotation of the bone screw. The particularly complete longitudinal extension of the two sub-areas allows for a large relative surface area of ​​the two sub-areas relative to the total surface area of ​​the threaded section. A large relative surface area of ​​the two sub-areas enables good anchorage of the bone screw in the bone and low migration of the bone screw out of the bone.

[0055] According to a further advantageous aspect of the present disclosure, one of the two sub-areas can be blasted from a first side after forming the part. The other of the two sub-areas can be blasted from a second side, opposite a mid-plane of the bone screw in which an axis of rotation of the bone screw lies. The tip section can be omitted in this process.

[0056] In other words, the two sections of the threaded portion can be prepared / manufactured from two opposite sides of the bone screw after turning, blasting, grinding, tumbling, rolling, pressing, cutting, milling, or similar processes using a blasting technique such as compressed air blasting, particularly with corundum or similar materials. The central plane to which each of the two sections is prepared / manufactured can be any plane of the bone screw or threaded portion in which the axis of rotation of the bone screw or threaded portion lies. Preferably, the screws, especially the head and tip sections, are machined after turning, blasting, grinding, tumbling, rolling, pressing, cutting, or milling using a conventional machining process such as matte finishing / glass bead etching. Subsequently, the specially roughened sections are produced.

[0057] This allows at least some of the sharpness of the tip section, in particular the sharpness of the at least one cutting edge that exists after the threaded screw has been shaped, to remain unaffected by blasting with abrasive media (e.g., corundum) and thus not become dull. This reduces the screw-in resistance and makes screwing easier.

[0058] Preferably, the partial circumferential area of ​​the threaded section can be covered and thus omitted after the shaping of the bone screw for blasting with abrasive media (e.g., corundum), i.e., not blasted.

[0059] By covering the threads, at least in sections, the sharpness of the threads, which exists after the shaping process, can remain unaffected by blasting with abrasive media (e.g., corundum) and thus not become dull.

[0060] According to a further advantageous aspect of the present disclosure, the at least one partial region can extend along an axis of rotation of the bone screw. In particular, the at least one partial region can extend over more than 50, 60, 70, 80, 90, 95% of the total length of the threaded section or over the entire length of the threaded section.

[0061] In other words, at least one part of the screw can extend in the longitudinal direction of the bone screw, in particular completely in the longitudinal direction of the threaded section.

[0062] The complete longitudinal extension of at least one sub-section allows for a large relative surface area of ​​this sub-section relative to the total surface area of ​​the threaded section. This large relative surface area ensures good anchorage of the bone screw in the bone and thus prevents migration of the bone screw out of the bone.

[0063] According to a further advantageous aspect of the present disclosure, the surface roughness can transition into the surface roughness of the at least one sub-area at least in at least one area adjacent to the at least one sub-area and / or the surface roughness can transition into the surface roughness of the pointed section at least in at least one area adjacent to the pointed section.

[0064] In other words, the surface roughness in a region adjacent to the subregion and / or the tip section may exhibit a gradient. At the transition between the region and the subregion and / or the tip section, the surface roughness of the region may correspond to the surface roughness in the subregion or the surface roughness of the tip section.

[0065] This eliminates the need for harsh transitions when providing / producing surface roughness. The surface roughness in at least one sub-area can be provided / produced according to the desired surface roughness, while in the surrounding areas of this sub-area, the surface roughness transitions continuously to the surface roughness present after the forming process.

[0066] Preferably, the surface roughness in the at least one sub-area transitions into the surface roughness of the tip section and / or the surface roughness in the at least one sub-area transitions into the surface roughness in the at least one partial circumferential area and / or the surface roughness in the at least one partial circumferential area transitions into the surface roughness of the tip section.

[0067] Furthermore, the transitions can preferably be continuous.

[0068] According to a further advantageous aspect of the present disclosure, at least one sub-area can be blasted after the shaping process, and the tip section can be omitted.

[0069] In other words, at least one section of the threaded portion can be prepared / manufactured after turning, blasting, grinding, tumbling, rolling, pressing, cutting, milling, or similar processes on the bone screw using a blasting technique such as compressed air blasting, particularly with corundum or similar materials. Preferably, the tip section can be covered with abrasive media (e.g., corundum) after the bone screw has been shaped, thus avoiding blasting. This allows at least part of the tip section, and especially the sharpness of the at least one cutting edge present after the threaded screw has been shaped, to remain unaffected by blasting with abrasive media (e.g., corundum) and thus prevent dulling. This reduces the insertion resistance and facilitates insertion.

[0070] According to a further advantageous aspect of the present disclosure, the screw head can have a surface roughness in at least one screw head region that differs from the surface roughness in the at least one sub-region. Preferably, the surface roughness of the screw head region (functionally) corresponds (substantially) to the surface roughness of the tip section. Equally preferably, the screw head region can have the lowest surface roughness of the bone screw. Particularly preferably, the screw head region can have a lower surface roughness than the tip section. Equally preferably, the screw head region can have a lower surface roughness than the sub-region of the thread section or than the entire thread section.Particularly preferably, the surface roughness of the tip section can be lower than the surface roughness of the partial area of ​​the thread section or the threaded section and higher than the surface roughness of the screw head partial area or the screw head.

[0071] This allows the screw head to glide smoothly over implants, such as anterior cervical plates, during fixation – both intraoperatively during insertion and postoperatively under load. After shaping, the screw, or rather the screw head, can be finished using a standard process such as matte or glass bead etching.

[0072] Preferably, the screw head section can extend over the entire screw head. According to an alternative, optional aspect of the present disclosure, the screw head can also have a surface roughness in at least one screw head section that (essentially) corresponds to or (functionally) closely approximates the surface roughness in the at least one sub-section.

[0073] This allows the screw head to generate additional friction when fixing implants such as anterior cervical plates, thus providing further security against the bone screw unscrewing. Furthermore, the screw head can be sandblasted, at least in sections, after its forming process.

[0074] According to a further advantageous aspect of the present disclosure, the bone screw can have a shank, which is formed, in particular, between the screw head and the threaded section. The shank can have a surface roughness in at least one shank section that differs from the surface roughness in the at least one sub-section. Preferably, the surface roughness in the shank section can be the same as the surface roughness of the tip section. Equally preferably, the shank section, particularly together with the screw head section, can have the lowest surface roughness of the bone screw. Particularly preferably, the shank section can have a lower surface roughness than the tip section. Equally preferably, the shank section can have a lower surface roughness than the sub-section of the threaded section or than the entire threaded section.Preferably, the surface roughness of the tip section can be lower than the surface roughness of the threaded section or the entire threaded section, and higher than the surface roughness of the shaft section or the entire shaft. This allows for low-friction contact between the bone screw and the plate, both intraoperatively during insertion and postoperatively under load. Furthermore, the reduced stress concentration can increase the biomechanical fatigue strength of the bone screw.

[0075] Preferably, the shank section can extend over the entire shank. Preferably, the surface roughness in at least one part of the thread section, in particular in the entire thread section, can be higher than any of the surface roughnesses of the screw head section, in particular the screw head, the shank section, in particular the shank, and the tip section.

[0076] After shaping, the shaft can be finished using a standard machining process such as matting / glass bead matting.

[0077] According to a further advantageous aspect of the present disclosure, the local surface roughness within the at least one sub-region and / or the local surface roughness within the tip section can vary. The averaged surface roughness of the at least one sub-region can differ from the averaged surface roughness of the tip section.

[0078] This allows the surface roughness of the tip section to be adjusted to the screwing / pre-drilling / displacement of the bone when screwing the bone screw into the bone, even with locally varying surface roughness, while the surface roughness of the thread section can be adjusted to the anchoring of the bone screw in the bone and the prevention of migration of the bone screw or loosening of the bone screw from the bone.

[0079] Brief description of the characters

[0080] The disclosure is explained in more detail below with reference to preferred embodiments and the accompanying figures.

[0081] Fig. 1 shows an isometric view of the bone screw according to one embodiment of the present disclosure; Fig. 2 shows an isometric view of the bone screw according to another embodiment of the present disclosure;

[0082] Detailed description of the figures

[0083] Fig. 1 shows a self-tapping bone screw 1 with a lens-shaped screw head 2, a substantially cylindrical central threaded section 3 and a substantially frustoconical tip section 4 formed on a side of the threaded section 3 opposite the screw head 2.

[0084] A hatched section 5 of the thread segment 3 extends over part of a surface of a thread root 6, part of each surface of the two thread flanks 7, which are at a flank angle to each other, and part of a surface of a tooth flank 8 pointing outwards in the radial direction 10. The radial direction 10 of the bone screw 1 refers to an axis of rotation 12 of the bone screw 1. Section 5 of the thread segment 3 extends circumferentially 11 over the entire circumference of the bone screw 1. Section 5 of the thread segment 3 also extends along the axis of rotation 12 approximately over the entire length L of the thread segment 3.

[0085] The screw head 2 of the bone screw 1 has a larger diameter, i.e., a greater extent in the radial direction 10, than the threaded section 3 and the tip section 4. A hatched screw head part area 13 extends over part of a surface of the screw head 2.

[0086] Between the screw head 2 and the threaded section 3, a shaft 14 is formed that tapers conically along the axis of rotation 12 towards the tip section 6. A hatched section 15 of the shaft extends over part of a surface of the shaft 14.

[0087] Cutting blades 16 are formed on the tip section 4, which cut into or bore into the bone when the bone screw 1 is screwed in. The cutting blades 16 are each formed by a wedge-shaped recess 17 in the tip section 4. Furthermore, conical tip threads 18 are formed on the tip section 4, which are interrupted by the wedge-shaped recesses 17 and thus form partial tip threads 19.

[0088] The surface roughness in sub-area 5 differs from the surface roughness of the screw head 2, the shaft 14, and the tip section 6. The surface roughness in sub-area 5 is greater than that of all other surfaces of the bone screw 1. Sub-area 5 is roughened by alumina blasting, which results in the greater surface roughness in sub-area 5.

[0089] Fig. 2 shows the bone screw 1 from Fig. 1, wherein the threaded section 3 has two hatched sub-sections 5, which are separated by a partial circumferential section 9 extending along the axis of rotation 12 from the shank 14 to the tip section 6. The partial receiving section 9, as well as the two sub-sections 5, extends over parts of the surface of the thread root 6, over parts of the surface of the two thread flanks 7, which are at a flank angle to each other, and over parts of the surface of the tooth flank 8, which points outwards in the radial direction 10. The two sub-sections 5 of the threaded section 3 extend in the circumferential direction 11 over a part of the circumference of the bone screw 1. The sub-sections 5 of the threaded section 3 also extend along the axis of rotation 12 over approximately the entire length L of the threaded section 3.

[0090] The surface roughness of sub-areas 5 differs from the surface roughness of the screw head 2, the shaft 14, the circumferential region 9, and the tip section 6. Specifically, the surface roughness of sub-areas 5 is greater than that of all other surfaces of the bone screw 1. Sub-areas 5 are roughened by abrasive blasting, resulting in their greater surface roughness. The circumferential region 9, located between sub-areas 5, is not blasted with abrasive media and is therefore not roughened.

[0091] In summary, the present disclosure relates to a bone screw, in particular of the self-drilling screw type, comprising a screw head, a threaded section and a tip section having or forming a cutting edge, wherein the threaded section has at least in at least a partial area or in its entirety a surface roughness that differs from the surface roughness of the tip section, in particular a greater surface roughness.

[0092] List of reference signs

[0093] 1 bone screw

[0094] 2 screw heads

[0095] 3 thread section

[0096] 4 Top section

[0097] 5 sub-area

[0098] 6 Thread base

[0099] 7 Thread flank

[0100] 8 Tooth flank

[0101] 9 Sub-scope area

[0102] 10 Radial direction

[0103] 11 Circumferential direction

[0104] 12 Rotation axis

[0105] 13 Screw head area

[0106] 14 shaft

[0107] 15 shaft section area

[0108] 16 cutting blade

[0109] 17 Exclusion

[0110] 18 peak threads

[0111] 19 partial threads

[0112] Length L

Claims

Patent claims 1. Bone screw (1) in particular of the self-drilling screw type with - a screw head (2), - a threaded section (3) and a tip section (4) having or forming a cutting blade (16), characterized by the fact that the thread section (3) has a surface roughness in at least one sub-area (5) that differs from the surface roughness of the tip section (4).

2. Bone screw (1 ) according to claim 1 , characterized in that the surface roughness in the at least one partial area (5) is higher than in the tip section (4).

3. Bone screw (1 ) according to claim 2, characterized in that the surface roughness in the at least one partial area (5) is provided by surface treatment in the micro range.

4. Bone screw (1) according to one of the preceding claims 1 to 3, characterized in that the at least one partial area (5) extends at least partially circumferentially to the bone screw (1), in particular fully circumferentially to the bone screw (1), over the thread base (6), thread flank (7) and tooth flank (8) of the thread section (3).

5. Bone screw (1) according to one of the preceding claims 1 to 3, characterized in that at least two partial areas (5) are provided which are spaced apart from each other in the circumferential direction (11).

6. Bone screw (1) according to claim 5, characterized in that the threaded section in at least one partial circumferential region (9) located between the at least two partial regions (5) has a surface roughness which differs from the surface roughness in the at least two partial regions (5) and preferably corresponds to the surface roughness of the pointed section (4).

7. Bone screw (1 ) according to claim 5 or 6, characterized in that two circumferentially spaced partial regions (5) are provided, wherein the two partial regions (5) are formed on opposite sides of a median plane of the bone screw (1) in which an axis of rotation (12) of the bone screw (1) lies and preferably extend along the axis of rotation (12) of the bone screw (1), in particular over more than 50, 60, 70, 80, 90, 95% of the total length (L) of the threaded section (3) or over the total length (L) of the threaded section (3).

8. Bone screw (1 ) according to claim 7, characterized in that one of the two partial areas (5) is blasted from a first side after a forming process, the other of the two partial areas (5) is blasted from a second side opposite a median plane of the bone screw (1) in which a rotation axis (12) of the bone screw (1) lies, and the tip section (4) is omitted.

9. Bone screw (1 ) according to one of claims 1 to 6, characterized in that at least one partial area (5) extends along an axis of rotation (12) of the bone screw (1), in particular over more than 50, 60, 70, 80, 90, 95% of the total length (L) of the threaded section (3) or over the total length (L) of the threaded section (3).

10. Bone screw (1) according to one of claims 1 to 9, characterized in that the surface roughness at least in one area adjacent to the at least one sub-area (5) transitions into the surface roughness of the at least one sub-area (5) and / or the surface roughness at least in one area adjacent to the pointed section (4) transitions into the surface roughness of the pointed section (4).

11. Bone screw (1) according to one of claims 1 to 10, characterized in that the at least one partial area (5) is blasted with abrasive media after the shaping process and the tip section (4) is omitted.

12. Bone screw (1) according to one of claims 1 to 11, characterized in that the screw head (2) has a surface roughness in at least one screw head part area (13) which differs from the surface roughness in the at least one part area (5) and preferably corresponds to the surface roughness of the tip section (4).

13. Bone screw (1) according to one of claims 1 to 12, with a shaft (14) which is formed in particular between screw head (2) and threaded section (3), characterized in that the shaft (14) has a surface roughness in at least one shaft part area (15) which differs from the surface roughness in the at least one part area (5) and preferably corresponds to the surface roughness of the tip section (4).

14. Bone screw (1) according to one of claims 1 to 13, characterized in that a local surface roughness varies within the at least one sub-area (5) and / or within the tip section (4) and the average surface roughness of the at least one sub-area (5) differs from the average surface roughness of the tip section (4).

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