DE102009033138A1 - Screw for compression of bones, has head thread section with cutting thread, where external dimension and/or core dimension of thread and/or external dimension and/or core dimension of thread section is reduced with respect to screw thread - Google Patents

Abstract

The screw (1) has a head thread section (2) with a cutting thread (3), and a distal thread section (4) removably arranged towards the thread section. External dimension and/or core dimension of the thread and/or external dimension and/or core dimension of the thread section is reduced with respect to a screw thread and/or another screw thread or conically towards a thread-less shaft section (18). A conical attachment tip (9) is formed at an end of the distal section, where the end lies opposite to the shaft section. An edge hole is formed at an end region of the thread section. Independent claims are also included for the following: (1) a device for inserting a bone screw into bones for compression of bones (2) a magazine for receiving a screw, comprising horizontal plates (3) a kit for implantation of a screw in bones, comprising a centering pin.

Description

The Invention relates to a screw for insertion into a bone, in particular for the compression of bones, comprising a head thread section with a thread and one to the head thread portion away arranged distal threaded portion, which via a unthreaded shaft portion are connected together, as well as a Kit for the implantation of such a screw and its other individual elements.

State of the art

Out In the prior art are bone screws with a head threaded portion and a shaft threaded portion.

For example, the DE 695 25 111 T2 a screw for connecting small bone fragments, the screw having a head threaded portion which is connected via a shaft portion with a distal threaded portion. This screw is preferably used to connect small bone fragments, which makes re-implantation, ie removal of the screw and reinsertion without aids, difficult, since there are no corresponding devices for reimplantation on the screw. The screw has only cutting threads that assist in screwing or implanting the screw. Furthermore, the screw preferably consists of a biodegradable material, so that a reimplantation of this screw at a certain degree of degradation of the material of the screw is no longer possible.

Out DE 28 07 364 C2 Also, a bone screw is known, which has a head thread portion, a shaft portion and a threaded portion. A disadvantage of this bone screw is that steps are present between the respective threaded sections, in particular on the shaft section, which complicate both implantation and reimplantation of such a bone screw. Due to this step-like shape of the bone screw also several stepped holes before implanting the screw are necessary.

Objects of the invention

A Object of the present invention is to provide a screw for to provide the compression of bones that are easy and faster to implant and easy to reimplant. Another The object of the invention is a kit for inserting the screw with the o. g. To provide properties.

Solution of the task

to Solution of the task leads to an outside diameter and / or a core diameter of the cutting thread of the head thread portion and / or an outer diameter and / or a core diameter of the Threaded section related to the respective screw threads tree-like or conical to the unthreaded shank portion or taper away from him, as well as the characteristics of the siblings Claims.

These advantageous arrangement of the first and last screw simplified both implanting and reimplanting such Screw. Due to the conical tree-like design of the cutting thread the head thread portion or the distal threaded portion takes place a better anchoring of the bone screw in the respective bone. In general, the pilot hole for receiving the threaded portion cylindrically shaped. Due to the tree-like design of Cutting thread can be generated higher compression even if the hole is cylindrical. By this configuration also takes a much better power and power transmission. The implantation and especially the reimplantability is essential cheaper than "cylindrical" screws or "cylindrical" cutting threads.

Furthermore the threads can be single or multi-threaded.

In another advantageous embodiment of the screw according to the invention, a scraping groove is provided on at least one screw thread of the head thread section and / or of the distal thread section, so that both the screwing in of the screw and the unscrewing of the screw are simplified by this thread-cutting section. These Schabnuten especially in the last Screw threads of the distal threaded portion assist in unscrewing the screw, particularly after the screw has been left in the bone tissue for a long time to compress it. Because it is likely that also forms bone tissue on the shaft portion and the scrape groove serves as a safeguard against twisting, which can then be removed by means of the scraping groove of the last screw of the distal threaded portion when the screw is reimplanted.

In In another advantageous embodiment, the scraping groove the last screw of the distal threaded portion offset arranged to the cutting thread of the head thread portion. By the staggered arrangement of the scraper groove with respect to the cutting thread the head thread section is the unscrewing of the screw Reimplanting simplified, as this improved cutting options arise.

In another embodiment of the invention is the Scraping groove of the distal threaded portion opposite the scraper groove the head thread portion transverse to the shaft longitudinal direction staggered. The Schabnuten can also in other predetermined angles offset from each other or exactly opposite be arranged. Essential here is only that by the location the Schabnuten screwing in the respective threaded sections is simplified and that the partially accumulating waste material slightly along the screw threads out of the screw channel and bones can be brought out or the bone compacted.

In another advantageous embodiment of the screw is in addition to the first Schabnut additionally at least one further Schabnut present, being at the approach tip at the transition formed for axial recess at least one cutting recess is that is substantially tooth-shaped. Also this cutting recess supports the insertion of the screws into the bone together with the existing Schabnuten. Because these form on the Schraubgängen cutting edges, which is a screwing the screw support and improve.

In a further advantageous embodiment, the inventive screw at its insertion end a tip on the insertion of the screw in a pilot hole in the bone or screwing the screw into the bone easier. Advantageously, the attachment tip is cone-shaped. There are however, other approach tip shapes are conceivable, essential, that these facilitate insertion of the screw into a bone bore.

In a further embodiment of the inventive Screw is a Kantloch at an end portion of the head thread portion educated. This Kantloch serves that the screw by means of suitable screwdriver blades can be screwed. in this connection can the Kantloch as Torxkantloch, as Imbuskantloch o. The like. Formed be. Also suitable is a slot or Kreuzschlitzausgestaltung. It is essential that a secure screwing with a maximum power transmission to the screw feasible is.

Prefers the screw additionally has an axial recess, in the example, a centering pin can be used. The Axialaufnehmung serves as a centering when screwing into the bone material or Insertion of appropriate probe devices with which the screwing progress monitors can be.

In an advantageous embodiment of the screw are the threads the head thread and / or the distal threaded portion as Sägezahngewinde educated. However, other types of threads are conceivable. However, sawtooth threads have proven to be particularly advantageous exposed to the compression of bone.

Moreover has for faster screwing the inventive Screw the distal threaded sections a larger pitch as the thread on the head section. This allows the compression the bone. It is not mandatory. There are also other arrangements the thread pitches on the head thread portion and the distal threaded portion possible. For example, both can be the same Thread pitch, if desired.

For compression of a bone, it has proved to be advantageous that the pressure surfaces of the sawtooth thread point in the direction of the head thread section. However, other arrangements of the pressure surfaces of the sawtooth thread are possible. In the preferred embodiment, the pressure surfaces of the head thread point in the same direction as the pressure surfaces of the distal threaded portion. It is ever but also possible that the pressure surfaces point towards or away from each other. Furthermore, other types of threads can be used.

The inventive screw is advantageously by means of at least one of the inventive kit included Parts introduced into the bone tissue to be connected.

Prefers is in a previous step with an inventive, Adjustable step drill in one step a stepped bore drilled into the bone to be fixed. For this purpose, the step drill preferably also combined and formed by a centering pin or guidewire.

To the Insert the screw in a preferably pre-drilled hole points the device for introducing the screw a sleeve on, which preferably at its end portion a receptacle for insertion of the head thread portion of the screw is formed. By the recording The screw to be screwed into the bone tissue easier be screwed in, as this recording is a guide and Holding action for the screw provides. This accounts additional guide devices so that the screw do not tilt sideways when screwing in.

In an advantageous embodiment of the device is in the recording an internal thread provided, in which the head thread portion of Screw is at least partially screwed. By this screwing the screw is rotatably connected to the sleeve so that This can be screwed in easier by the sleeve or a Eindrehklinge provided thereon are twisted together.

These Eindrehklinge is in an advantageous embodiment of the device slidably mounted in the sleeve, so that between a receiving position for receiving the screw in the receptacle, a screwing position for screwing the screw and a mounting position adjustable for final positioning of the screw is.

In an advantageous embodiment of the device is the screwing blade biased by a force storage element towards receiving. For this purpose, shoulders are provided on the screw-in blade against which, for example a coil spring presses. The preload of the screwing blade However, it can also be accessed by other means respectively. For example, correspondingly elastic Inserts made of plastic or rubber may be provided, designed in such a way and arranged that the screwing blade towards receiving is pressed.

In An advantageous embodiment of the invention is also a Verrasteinrichtung provided. In a preferred embodiment the latching device is similar to a hexagon. For this purpose, a recess is provided in the sleeve, by a flat spring engages in the screwdriver blade and against rotation guaranteed. Through the recess two locking positions for provided the approach of the screwing blade. Here is the screwing blade preferably in a locked position in a screwed position and in the other latching position in a mounting position for the screw can be brought.

It However, there are also other latching devices for setting the respective Mounting and screwing positions of the screwing blade conceivable. Therefor For example, appropriate gearing or Verschraubverschlüsse be provided.

In an advantageous embodiment of the device has the screw-in blade additionally has an axial recess, with the axial recess of the inventive screw is in accordance bringable, so that by appropriate Probes, guide pins od. Like. Can be introduced.

To the facilitated screwing the device is also at least one Handle provided on the sleeve. There are more handles provided which are offset by 120 ° to each other. The handle or the handles are substantially perpendicular to the sleeve path. However, other forms of grip are also suitable for holding on facilitate the sleeve and twisting about its longitudinal axis.

For the implantation of a screw according to the invention is Conveniently, a kit comprising a step drill, a device for screwing the screw, a centering pin and a magazine covers, used.

Also, protection is claimed for such a step drill for introducing a Stufenboh into a bone for a screw, comprising a drilling step and a countersinking step, wherein the drilling step is variable in length. This has the advantage that the step drill is adaptable to the length of the selected bone screw.

Preferably is the sinker as a sleeve section of a depth gauge educated. Particularly preferred is the sleeve portion displaceable on the drilling stage or arranged screwed on this and according to the selected screw length a latching device for drilling can be fixed. This includes the Locking device preferably a flat spring with bolt and a Groove, these three elements for fixing a position in operative connection can be brought.

Especially The latching device preferably has a viewing window. By this can be read off the set screw length. This has the advantage that the screw length is very simple is adjustable.

Of Further, a mark is provided at the lowering stage, the indicates how far the screw can or must be screwed in. This is an additional help for the doctor during implantation.

Conveniently, is one in the drilling stage and in the countersink of the step drill Axialausnehmung provided. This can be advantageous for centering used in conjunction with a centering pin.

Especially Preferably, the step drill has a connection point analogous to the screwing blade on and is with the same grip as the screwing blade connectable. This facilitates the work of the doctor since he is only need to adjust to a handle shape, and reduces the kit to a component.

Preferably is the inventive bone screw in a magazine kept or provided for the operation, so that after sterilization without touching with the device for Screw in the screw, can be removed from the magazine. Is to the magazine according to the invention is preferably designed such that that the screw is positioned vertically and secure against rotation. In a particularly preferred embodiment, the Magazine according to the invention takeover loads, in operative connection stand with the cutting edges of the screw on.

figure description

Further Advantages, features and details of the invention will become apparent the following description of preferred embodiments as well as from the drawings; this shows in

1 a side view of an inventive screw for compression of bone not shown in detail;

2 a side view of the screw from 1 turned by 90 degrees;

3 a front view of the screw behind 2 ;

4 an end view of the screw from 2 ;

5 a longitudinal sectional view of the screw according to the section line VV of 2 ;

6.1 and 6.2 perspective views of the screw behind 1 ;

7 a side view of an inventive device for inserting the screw according to the 1 to 6 ;

8th an enlarged partial longitudinal view according to section line VIII-VIII in 7 ;

9 an enlarged partial section of a front end portion of the device for inserting a screw according to 7 ;

10 a side view of an inventive step drill;

11 a longitudinal section along section line XI-XI in 10 ;

12 a schematic representation of the introduction of a screw according to the invention in a bone;

13 a longitudinal section through a magazine with the inventive screw and the device for inserting the screw into a bone.

In 1 is a screw according to the invention 1 shown, which is intended for the compression of bone. The screw 1 has at its two end portions each have a head threaded portion 2 and a threaded portion disposed distally therefor 4 on. The head thread section 2 and the threaded portion 4 are over a threadless shaft section 18 connected with each other.

From the longitudinal section view of 5 is also apparent that the outer diameter of a first screw 6.1 and one last screw 6.n + 1 of the threaded portion 4 a smaller outer diameter than intermediate screw threads 6.n , n stands here as a placeholder for the number of screw threads, which may be different depending on the embodiment of the screw, as in the embodiment of the in the 1 to 6 shown inventive screw shown. This also applies to the number of screw threads 7.n of the head thread section 2 ,

Furthermore, the first screw thread 6.1 and the last thread 6.n + 1 of the threaded section 4 in each case at least one recess 8th . 5 on, such as in 1 shown. These recesses 8th . 5 are preferably designed as Schabnuten, so that cutting threads are formed.

How out 1 can be seen, the Schabnut 8th up to an adjacent screw thread 6.n extend, where there is the scraping groove 8.1 not fully penetrated the screw, but there forms only a Teilschabnut. The Schabnuten 8th and 8.1 Improve the application of bone material when screwing in and facilitate unscrewing or re-implantation of the screw by the Schabnuten 8th . 8.1 cut into the adherent, reincarnated cooking tissue there and this is not broken off or demolished, as it may be the case with known from the prior art screws without these Schabnuten.

In 3 is the starting point 9 the screw according to the invention 1 shown. This approach tip 9 fulfills several functions. First, its conical shape makes it easier to set the screw in a pre-drilled hole, and second, it has several scraper grooves 12 and 13 which facilitate and improve the screwing of the screw into the adjacent bone tissue.

As in 6 .2, the scraper groove extends 12 the nose tip 9 at least two screw threads 6.1 to 6.n while the scraping groove 13 , as in 1 shown just about a screw thread 6.1 extends. The Schabnuten 12 . 13 form in the associated Schraubgängen cutting edges, screwing the screw 1 facilitate in the adjacent bone tissue.

Out 6.1 and 6.2 is further to recognize that the head thread section 2 a cutting thread 3 having. The cutting thread 3 of the head thread section extends over four threads 7.1 to 7.n , as in 6.1 . 6.2 and 2 to recognize. The head thread section 2 has a much larger outer diameter, but a lower slope of the gears 7.n + 1 as the distal threaded portion 4 ,

In 4 Fig. 10 is a plan view of the end portion of the head thread portion 2 shown. In the end section is a Kantloch 10 formed, which can be designed to receive Torx, hexagonal or polygonal screwdriver blades. With a corresponding screwdriver blade, in the Kantloch 10 is used, the screw is 1 screwed into the designated bone tissue. As in 5 As can be seen, the Kantloch extends 10 at a predetermined depth in the head thread portion 2 ,

Out 5 It can also be seen that the screw 1 from an axial recess 14 is threaded through, in which a centering pin or wire is inserted, which is previously inserted into a bone to be compressed, so that a user screwing the screw is facilitated in a predetermined direction. The axial recess 14 extends through the entire screw 1 through the head thread section 2 and through the threaded section 4 , so each entrance and exit openings 27 . 28 are formed.

In the 1 and 5 is also to be seen that by the Schabnuten 12 and or 13 in each case a cutting recess in the inlet opening 27 Only one of them is with the reference number 15 characterized. These cutting recesses 15 additionally improve the penetration and cutting in of the screw 1 into the adjacent bone tissue.

The 7 to 13 show individual parts of a kit for inserting the screw 1 into a bone tissue. This comprises a step drill according to the invention 34 , according to the 10 and 11 that made a drill 35 and a depth gauge 36 consists. This is the drill 35 in its front area as a drilling stage 37 educated. The drill 35 is from an axial recess 38 traversed. After the drilling step 37 the drill expands 35 to a latching part 39 on. In this are circumferential grooves 40 formed. Between the circumferential grooves 40 are how out 10 indicates screw lengths marked.

The depth gauge 36 is designed as a sleeve on the drill 35 slidably arranged. The drilling stage 37 is doing of a lowering 41 embrace, on the markings 55 can be seen. To the sinking stage 41 closes a guide sleeve 56 on, which is a latching device 42 having. This is made of a flat spring 43 that with a latch 57 in one of the grooves 40 engages, educated. By moving the depth gauge 36 on the drill 35 can the length of the drill step 37 set and by the flat spring 43 the Verrasteinrichtung 42 be determined. The selected screw length is then through a viewing window 44 the Verrasteinrichtung 42 read.

In the 7 to 9 is further a device P for screwing in the inventive screw 1 according to the 1 to 6 shown. The device P has a screwing blade 21 on the one hand in one grip 24 is arranged and the other end in a sleeve 19 plugged. In this sleeve 19 is the screwing blade 21 with a tool section 29 arranged, for insertion into the Kantloch 10 the screw 1 is trained.

The tool section 29 is in the in 9 shown embodiment of the device P as a section for screwing a screw 1 with a Kantloch 10 , the Z. B. suitable for receiving Torxschraubendreherspitzen trained. The tubular shape of the tool section 29 results from the fact that in the screwing blade 21 an axial recess 26 is formed, with the axial recess 14 in the screw 1 communicates when the tool section 29 into the Kantloch 10 the screw 1 is used. The tool section 29 but can also be another desired embodiment according to the configuration of the Kantloches 10 have, which is suitable for insertion into the screw.

To control the position of the tool section 29 to the Kantloch 10 the screw 1 make up the sleeve 19 and the screwing blade 21 a latching device 25 out. This is indicated by the screwing blade 21 a V-shaped recess 30 on, in which a flat spring 31 can engage with a corresponding bulge. When the flat spring 31 with the bulge in the V-shaped recess 30 is engaged, is a screwing position in which the tool section 29 in engagement with the Kantloch 10 the screw stands, reached, so with the screwing blade 21 the screw 1 can be screwed.

Between sleeve 19 and screwing blade 21 is a force storage element 23 introduced, which is the screwing blade 21 opposite the sleeve 19 biases. This power storage element 23 has, as described later, the task of the sleeve 19 if the screw 1 partially screwed into the bone, pushing upwards to produce a mounting position in which there is a clear view of bone and screw.

For inserting and holding the screw 1 in the sleeve 19 is a recording 20 formed, in which the head thread portion 2 the screw 1 can be held releasably. In the recording 20 is also an internal thread 33 provided, which corresponds to the cutting thread 3 of the head thread section 2 the screw 1 is trained.

Further, for rotating or holding the sleeve 19 handle portions 22 provided that an independent turning of the sleeve 19 and the screwing blade 21 improve.

By means of an inventive modular system which is a magazine with screw according to the invention 1 , a centering pin 46 , the step drill 34 and the device P for screwing the screw 1 comprises, a screw according to the invention 1 in a bone 45 be implanted.

As in 12 is shown in a first step of the centering pin 46 in the bones 45 brought in. In a second step, the depth gauge is used 36 or a separate depth gauge 47 , This may also be included in a kit according to the invention, determines the required screw length.

The step drill according to the invention 34 is by means of his Verrasteinrichtung 42 adjusted to the correct drilling depth for the determined screw length. The depth of lowering of the sinking stage 41 is about the marks 55 controllable.

The resulting movement of drills 35 and depth theory 36 results in a spiral course (transition axial displacement and rotation), since the drill 35 in the sinking stage 41 to be led. For this purpose, the sinking stage forms in its interior helical strips, which are guided in grooves of the drilling step. Thus, the two parts can be moved against each other until the required screw length in a viewing window 44 is readable. After releasing the flat spring 43 the bolt connects 57 frictionally the drill 35 with the depth gauge 36 ,

In order to achieve sufficient guidance during drilling, the centering pin 46 in the axial recess 38 introduced. This will be a stepped bore 48 in the bones 46 predrilled.

The drilling is done until the mark 55 on the marking sleeve 41 at the level of the upper edge of the bone 45 lies. Now the drilling depth fits exactly to the selected screw length. To the screw 1 sinking in the bone can also be drilled deeper if necessary.

If the device P for screwing the screw 1 not yet assembled, is now the Eindrehklinge 21 together with the sleeve 19 with her free end under control 24 used and locked there in any way. A flattened end 58 the screwing blade 21 acts with a corresponding flattening in the handle 24 for producing a rotation lock together.

The sleeve 19 is then axially displaced until the latching device 25 attacks. This means that the tool section 29 in the recording 20 for inserting the head thread portion 2 the screw 1 located.

The screw 1 Now with the device P for screwing the screw from a magazine 49 , as in 13 shown, taken. The magazine 49 includes a top plate 50 and a lower plate 54 , The top plate 50 has breakthroughs 51 on, through which the device P on the screw 1 can be put on. On the lower plate 54 are coaxial with the breakthroughs 51 anti-rotation 52 , These form driving loads, with the head thread section 2 or a groove 11 the screw 1 interact. So now is the screw 1 when screwing the recording 20 securely positioned against rotation so that they can be removed from the magazine with the device P without having to be touched.

The sleeve 19 or recording 20 Now on the screw 1 psyched. An unillustrated driving spring on the tool section 29 slips into a square surface of the square hole 10 , The sleeve 19 is on the head thread section 2 unscrewed and, after this already secured in the recording 20 is located, the driving spring reaches the bottom of the Kantloch 10 , A further rotation causes a retraction of the screwing blade 21 so that the latching device 25 is solved and the tool section 29 After also the driving spring has a corresponding recess in the axial recess 14 the screw 1 found in the Kantloch 10 retracts. This happens under the pressure of the energy storage element 23 , The doctor can now use the screw 1 from the magazine 49 to take.

from The idea of the invention is also encompassed by the tool section without Driving spring form, with a back pushing the screw-in blade is made by an end face of the screw. Here are other possibilities conceivable.

The insertion of the screw 1 in the recording 20 has the advantage that when screwing in the screw 1 into the stepped bore 48 no support brackets are needed, so that the screw does not tip away sideways, it can not get out of the receptacle 20 fall out, it is faster and easier without help in the stepped bore 48 used.

In the two-stage hole 48 now the screw 1 screwed by means of the device P. This is done with the screw 1 on the already in the bone 45 located centering pin 46 placed. The doctor turns the handle 24 and the screw 1 is by means of the screwing blade 21 into the pre-drilled stepped bore 48 turned turns until an end face 32 the sleeve 19 on the bone 45 rests and thus also a precompression z. B. a bone fracture arises.

Then then the sleeve 19 at the handle sections 22 held tight and continued until the head thread section 2 the screw 1 from the internal thread 33 the recording 20 turned out. After separating the two threads 33 and 7 is the by the force storage element 28 preloaded screwing blade 21 from the sleeve 19 pushed out or the sleeve 19 towards the handle 24 shifted so that it is apparent how far the screw 1 now by means of the screwing blade 21 still needs to be screwed or can. This is the sleeve 19 even further to the handle 24 towards a rest position 59 shifted, in which the tool section 29 far from the sleeve 19 or the recording 20 showing. This can now again in the Kantloch 10 used and the screw 1 be screwed further into the bone.

Finally, the screwing blade 21 from the centering pin 46 removed and the latter from the bone 45 away. LIST OF REFERENCE NUMBERS 1 screw 34 Step drills 2 Head threaded portion 35 drill 3 cutting thread 36 depth gauge 4 threaded portion 37 drill 5 recess 38 axial recess 6 screw thread 39 Verrastteil 7 screw thread 40 groove 8th Recess / Schabnut 41 Senkstufe 9 neck lace 42 latching device 10 square hole 43 flat spring 11 groove 44 window 12 Schabnut 45 bone 13 Schabnut 46 Centering 14 axial recess 47 depth gauge 15 Schneidausnehmung 48 stepped bore 16 buttress 49 magazine 17 print area 50 upper plate 18 shank portion 51 breakthrough 19 shell 52 twist 20 admission 53 opening 21 Eindrehklinge 54 lower plate 22 handle portion 55 mark 23 Power storage element 56 guide sleeve 24 Handle 57 bars 25 latching device 58 flattened end 26 axial recess 59 detent position 27 entrance opening P contraption 28 output port 29 tool section 30 recess 31 flat spring 32 face 33 inner thread

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 69525111 T2 [0003]
• - DE 2807364 C2 [0004]

Claims (30)

Screw ( 1 ) for insertion into a bone, in particular for compression of bone, comprising a head thread section ( 2 ) with a thread ( 3 ) and one to the head thread section ( 2 ) remotely located distal threaded portion ( 4 ), which have a threadless shaft section ( 18 ) are interconnected, characterized in that an outer diameter and / or a core diameter of the cutting thread ( 3 ) of the head thread section ( 2 ) and / or an outer diameter and / or a core diameter of the threaded portion ( 4 ) relative to the respective screw threads ( 6 ) respectively. ( 7 ) tree-like or conical to the threadless shaft section ( 18 ) or taper away from it. Screw according to claim 1, characterized in that on the shaft portion ( 18 ) opposite end of the distal threaded portion ( 4 ) a cone-shaped approach tip ( 9 ) is trained. Screw according to claim 1 or 2, characterized in that the distal threaded portion ( 4 ) and / or the head thread section ( 2 ) a sawtooth thread ( 16 ). Screw according to claim 3, characterized in that the pressure surfaces ( 17 ) of the sawtooth thread ( 16 ) in the direction of the head thread section ( 2 ) and substantially perpendicular to the longitudinal axis of the screw ( 1 ). Screw according to at least one of the preceding claims, characterized in that in the end region of the head thread portion ( 2 ) a Kantloch ( 10 ) is trained. Screw according to claim 5, characterized in that the Kantloch ( 10 ) is designed for receiving Torx, hexagonal and / or polygonal Eindrehklingen Screw according to at least one of claims 1-6, characterized in that at least one last thread ( 6.n + 1 ) of the distal threaded portion ( 4 ) with a recess / scraping groove ( 8th . 8.1 ) is provided. Screw according to claim 7, characterized in that the recess / Schabnut ( 8th . 8.1 ) offset from the cutting thread ( 3 ) of the head thread section ( 2 ) is arranged. Screw according to claim 7 or 8, characterized in that the scraping groove ( 8th . 8.1 ) of the distal threaded portion ( 4 ) opposite a scraper groove ( 11 ) of the head thread section ( 2 ) is arranged offset transversely to the shaft longitudinal direction. Screw according to at least one of claims 7 to 9, characterized in that offset from a first scraper groove ( 12 ) of the distal threaded portion ( 4 ) at least one second scraper groove ( 13 ) at the end portion of the distal threaded portion ( 4 ) is provided, so that at least one cutting recess ( 15 ) is trained. Screw according to at least one of the preceding claims, characterized in that the screw ( 1 ) of an axial recess ( 14 ) is penetrated for receiving a centering pin or wire. Step drill for introducing a stepped bore ( 48 ) into a bone ( 45 ), for a screw ( 1 ), comprising a drilling step ( 37 ) and a sinking stage ( 41 ), characterized in that the drilling step ( 37 ) is variable in length. Step drill according to claim 12, characterized in that the lowering step ( 41 ) Part of a guide sleeve ( 56 ) of a depth theory ( 36 ). Step drill according to claim 12 or 13, characterized in that the lowering step ( 41 ) at the drilling stage ( 37 ) is arranged displaceable / screwable and optionally according to the selected screw length via a latching device ( 42 ) to the drilling stage ( 37 ) is fixable. Step drill according to claim 14, characterized in that the latching device ( 42 ) a flat spring ( 43 ) on the guide sleeve ( 56 ) and at least one groove ( 40 ) in a latching part ( 39 ) of the drilling stage ( 37 ). Step drill according to claim 14 or 15, characterized in that the latching device ( 42 ) a viewing window ( 44 ) having. Step drill according to one of claims 12 or 16, characterized in that at the lowering step ( 41 ) at least one marker ( 55 ) is provided. Step drill according to one of claims 12 to 17, characterized in that in the drilling step ( 37 ) and in the sinking stage ( 41 ) an axial recess ( 38 ) is provided. Step drill according to one of claims 12 to 18, characterized in that the step drill ( 34 ) a connection with a handle ( 24 ) having. Device for inserting a bone screw ( 1 ) in a bone, in particular for a compression of bone, comprising a head thread section ( 2 ) with a cutting thread ( 3 ) and a thread portion distally disposed to the head thread portion ( 4 ), which have a threadless shaft section ( 18 ), characterized in that a sleeve ( 19 ) is provided, in which at one end portion a receptacle ( 20 ) for receiving the head thread section ( 2 ) is trained. Apparatus according to claim 20, characterized in that in the receptacle ( 20 ) an internal thread ( 33 ) for screwing in the head thread section ( 2 ) is trained. Device according to claim 20 or 21, characterized in that in the sleeve ( 19 ) a screwing blade ( 21 ) is slidably mounted, which can be pushed out of the sleeve and of the sleeve ( 19 ) is at least partially surrounded. Device according to claim 22, characterized in that the screwing blade ( 21 ) by means of a force storage element ( 23 ) in the sleeve ( 19 ) is biased. Device according to at least one of claims 20 to 23, characterized in that on the receiving ( 20 ) opposite end portion of the sleeve ( 19 ) a grip portion ( 22 ) is trained. Device according to one of claims 20 to 24, characterized in that the screwing blade ( 21 ) between a screwing position in which the screwing blade ( 21 ) in engagement with a Kantloch ( 10 ) one in the recording ( 20 ) screw ( 1 ), and a mounting position is displaceable, in which the screwing blade ( 21 ) to the recording ( 20 ) or the Kantloch ( 10 ) is spaced. Device according to claim 25, characterized in that the screwing blade ( 21 ) and the sleeve ( 19 ) a latching device ( 25 ), so that the screwing blade ( 21 ) in the screwing and / or the mounting position can be latched. Device according to Claim 26, characterized in that the latching device ( 25 ) a flat spring ( 31 ), which are provided with a V-shaped recess ( 30 ) is operatively connected. Device according to at least one of claims 20 to 27, characterized in that the screwing blade ( 21 ) an axial recess ( 26 ) having. Magazine for holding at least one screw ( 1 ), comprising at least one horizontal plate ( 50 . 54 ) with apertures for horizontal positioning of the screw, characterized by entrainment keys operatively connected to a head threaded portion ( 2 ) of a screw, so that the screw ( 1 ) is held against rotation. Kit for the implantation of a screw ( 1 ) into a bone, comprising at least one centering pin ( 46 ), a step drill ( 34 ), a device (P) for screwing in the screw ( 1 ) and / or a magazine ( 49 ),

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