DE102018102854A1 - shaft instrument - Google Patents

Abstract

In the present invention is a shaft instrument (S) for a handle (5) with a cutting jaw (1), an inner tube (8) and an outer tube (9), wherein the inner tube (8) forms a suction channel (17) and Includes pressure equalization port (10).

Description

Technical area

The invention relates to a shank instrument with a cutting jaw for medical applications according to the preamble of claim 1.

State of the art

In the medical or surgical field, devices for separating, punching and removing tissue and tissue parts, in particular from a body of a living being, are already known and in use in a variety of forms and configurations. From the DE 20 2009 002 433 U1 For example, a surgical instrument is known, which is also referred to as a sliding shaft instrument and has the task to separate by means of a punching function body tissue, cartilage or the like. Here, however, there is the problem that the thus separated tissue is not automatically removed and remains in the area of the punch. In addition, the application of increased force by the user is required for the stamping operation, which may result in reducing the necessary precision in the application. There is also the danger of injuring further tissue.

From the DE 10 2015112 716 A1 With regard to the problem of transporting separated tissue, a device for separating and removing tissue parts is disclosed. In this case, a suction channel is included in the instrument, which allows to carry away the separated tissue by a volume flow. In addition, a rinsing function is provided, wherein supplied liquid is intended to improve the removal of the separated tissue through the suction channel. The disadvantage here is that the suction can only be done when the intended for the separation of the tissue punch is open, otherwise the prevailing negative pressure in the suction or in the area of the punch makes an extraction impossible. Furthermore, there is the disadvantage that tissue is often sucked into the region of the punch by the suction function, which is not intended for separation or for removal or for removal. This problem complicates the application and may result in unwanted tissue separation or tissue injury during medical / surgical procedures.

Object of the invention

The object of the present invention is to overcome the disadvantages of the prior art. In particular, a device is to be provided which prevents tissue from being inadvertently sucked. Furthermore, a comprehensive suction function should be able to take place even when the punching or cutting device is closed. In addition, the precision in handling the device should be improved.

Solution of the task

To achieve the object, the features according to claim 1.

Advantageous embodiments are described in the subclaims.

The shank instrument according to the invention is a medical or surgical device for cutting off and removing tissue and tissue parts, in particular from a body of a living being. The shank instrument is pin-shaped and oval shaped in its cross section and is used for use in a handle and brought into operative connection with this. After use or the medical or surgical intervention, the shaft instrument is again separated from the handle. This modular construction has advantages in particular in the area of sterilization, material saving and handling.

Depending on the embodiment, the handle is provided either as a so-called disposable handle, which is disposed of after use, or as a classic handle that can be reused after use and medical sterilization provided.

In a further embodiment it is provided that the shaft instrument is firmly connected to the handle. In this one-piece embodiment, two variants are also provided. The first variant is designed so that it can be sterilized after use and then reused. This variant consists largely of suitably durable materials, such as suitable metals.

In the second one-piece variant is a holistic disposable variant in which the firmly connected to the handle shaft instrument is largely made of plastics and disposed of after first use.

The provision of these different disposable and reusable applications makes it possible to provide the shank instrument according to the invention for the most diverse medical requirements and areas of application, which is why it can be easily incorporated into the individual instrument selection.

The inventive shaft instrument has a distal end and a proximal end. In the area of the distal end of the shaft instrument, a cutting jaw is arranged. In the region of the proximal end, a recess and a connection are arranged.

The shank instrument according to the invention has an outer tube and an inner tube arranged therein. Both the outer tube and the inner tube each have a cone, at which the shank instrument tapers in the direction of a distal end of the shank instrument.

A rail emerges from the outer tube in the region of the distal end of the shaft instrument according to the invention. About this rail, the outer tube is connected to a jaw tip.

The outer tube furthermore has the recess in a region at a proximal end of the shaft instrument. This recess releases a part of the inner tube movably arranged in the outer tube.

The inner tube is movably disposed in the outer tube and forms a suction channel. The suction channel of the inner tube starts accordingly at a cutting edge and ends at a connection. The connection is in the direction of the distal end with the inner tube or a suction channel in connection and can be operatively connected by insertion into the handle in the proximal direction with the connection element. Through the connection element of the handle a suction function is made possible, in which a connection to an external medical pump is made. This extraction function is based on a volume flow, which develops its suction effect in the region of the cutting mouth and in the suction channel of the inner tube. All tissue parts cut by the cutting jaw should be sucked off. Furthermore, a rinsing function is integrated in the connecting element of the grip piece, which allows liquids, for example water, to be introduced into the inner tube or the suction channel so as to improve the suction function within the suction channel.

In the region of the recess of the outer tube, the inner tube has at least one bolt bearing and a bolt arranged therein. About this bolt is made by a coupling in the form of a U-profile of the handle, the movement of the inner tube within the outer tube. In preferred embodiments, two opposing pin positions or two opposing pins are preferably arranged in the region of the recess on the inner tube. Here, of course, other coupling solutions are possible and provided, which allow the inner tube within the outer tube and to move over the recess by the operation of the handle.

Through the connection of the inner tube, a connection is made to a connection element in the interior of the handle.

In the area of the distal end of the shaft instrument, the inner tube has pressure equalization holes. These pressure equalization openings pass through the inner tube and are therefore in operative connection with the suction channel.

In the present exemplary embodiment, two times eight pressure compensation openings are provided on the inner tube, with eight each being arranged in the region of the distal end in a uniform and mutually offset pattern. Each pressure equalization opening is in the preferred embodiment of the same size and executed in the form of a slot and arranged, wherein the longitudinal side of the slot-shaped pressure equalization openings in the distal / proximal direction, ie in the longitudinal direction of the shank instrument, are aligned. Of course, according to the invention, other formations and arrangements are possible and the number of pressure equalization openings variable.

With a distance to the pressure compensation openings, this distance may vary from embodiment to exemplary embodiment, engages a cutting edge at the distal end of the inner tube. This cutting edge is formed horseshoe-shaped and sharpened according to the medical-surgical application of the shank instrument on a cutting surface. The open area of the horseshoe-shaped cutting edge is guided in a guide rail. This guide rail is arranged on the rail, which in turn emerges from the outer tube.

The guide rail allows in conjunction with the rail an exact alignment of the cutting edge and the inner tube on a counter-cutting piece, which also has a horseshoe-shaped shape. The counter-cutting piece is arranged on the side of the jaw tip which is directed in the direction of the proximal end of the shank instrument. Both the cutting edge and the counterblade include sharp cutting edges suitable for medical applications.

The cutting jaw is formed by the end of the inner tube with the pressure equalization holes and the cutting edge and the end of the outer tube, which forms the guide rail with the rail for the cutting edge and the jaw tip with the counter-cutting piece.

If the inner tube is moved within the outer tube in the direction of the distal end of the shank instrument, ie in the direction of the jaw tip, the cutting jaw closes. This movement takes place by the actuation of a lever on the handle which is brought into operative connection via a coupling in the form of a U-profile with the bolts of the inner tube.

The cutting edge engages in the closed position, the counter-cutting piece. This overarching process, which represents the actual cutting process of the shank instrument according to the invention, is to be compared with the shearing principle. With the scissor principle, the two scissor blades with their cutting edges always travel directly one at a time, whereby the cutting effect comes about. A similar cutting effect takes place by the overreaching of the counterblade by the cutting edge. For this purpose, the cutting edge and the counter-cutting piece have a special cutting geometry to each other. This cutting geometry refers to an angular position of the cutting edge to counterblade or their cutting surfaces or cutting each other. This angle is 20 degrees in preferred embodiments. Of course, deviations are possible and provided here, as long as the described effect is maintained. This is especially true when it comes to embodiments in different sizes of the shaft instrument.

By the principle of scissors and the cutting edge geometry of the cutting edge in conjunction with the counter-cutting piece is achieved in an advantageous manner that the expended cutting force is significantly reduced. In addition, this present cutting geometry, compared to conventional punches, allows for a fine and clean cut that causes minimal injury and does not result in any bruising or tearing of tissue.

The cutting jaw is in an open position when not in use, with the cutting edge and counterblade not in contact. In this rest position, at least two of the pressure compensation openings encompassed on the inner tube are exposed and are not covered or closed by the outer tube. By means of these exposed pressure compensation openings, it is advantageously prevented that tissue is undesirably sucked into the cutting mouth before a cutting operation, since the volume flow at the cutting mouth is reduced by the two exposed pressure compensation openings. This volume flow reduction caused by the exposed pressure equalization openings leads to the fact that only tissue is sucked in, which is in the immediate vicinity of the cutting mouth. In addition, it is also possible through the exposed pressure equalization openings to remove the cutting mouth again without any cut from the possibly already aspirated tissue without causing injury by the suction and the new detachment.

Another significant advantage is that the cutting jaw does not have to be opened again directly after a cut made, as is the case with other known from the prior art instruments with punching and suction function. There, the punch mouth must be opened so that air can flow in order to compensate for the resulting negative pressure by the suction function, so that the die-cut tissue can be transported away with the volume flow.

In the case of the shank instrument according to the invention, all the pressure equalization openings on the inner tube, which are in operative connection with the suction channel, are free in the position of the closed cutting jaw, ie directly after the cut, and are not covered or closed by the outer tube. This allows that the removal of the cut tissue through the suction channel in the direction of the proximal end of the sheep instrument can already take place and takes place before the cutting mouth was opened again. On the one hand, a further risk of injury from adjacent tissue is minimized by the fact that the cutting mouth can be kept fired. On the other hand, a new cutting process is directly possible after opening the cutting jaw, since already in the closed position of the cutting jaw, the cut tissue could be removed by the exposed pressure equalization holes through the suction channel.

Of course, the opening of the cutting jaw automatically takes place via a spring enclosed in the handle, so that the bolts of the inner tube are again moved in the direction of the proximal end of the shaft instrument via the coupling in the form of a U-profile.

list of figures

• 1 eine Seitenansicht eines erfindungsgemässen Schaftinstruments mit geöffnetem Schneidmaul und einem Handgriff;
• 2 eine Seitenansicht des Schaftinstruments nach 1 mit teilweise geschlossenem Schneidmaul;
• 3 eine Schnittansicht entlang der Längsachse des Schaftinstruments nach 2;
• 4 eine vergrössert dargestellte Ansicht eines distalen Endes des Schaftinstruments gemäss 1;
• 5 eine vergrössert dargestellte Ansicht des distalen Endes des Schaftinstruments nach 5 mit geschlossenem Schneidmaul;
• 6 eine vergrössert dargestellte Ansicht des distalen Endes des Schaftinstruments gemäss 1 und 4 mit Winkelangaben zur Schneidgeometrie.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings; these show in:

• 1 a side view of a shank instrument according to the invention with opened cutting mouth and a handle;
• 2 a side view of the shaft instrument after 1 with partially closed cutting mouth;
• 3 a sectional view along the longitudinal axis of the shank instrument according to 2 ;
• 4 an enlarged view of a distal end of the shaft instrument according to 1 ;
• 5 an enlarged view of the distal end of the shaft instrument after 5 with closed cutting mouth;
• 6 an enlarged view of the distal end of the shaft instrument according to 1 and 4 with angles for cutting geometry.

embodiment

In 1 is a shaft instrument according to the invention S shown. With the shaft instrument S is a schematically illustrated handle 5 with a lever 13 and a connection element 15 shown.

The inventive shaft instrument S includes an outer tube 9 and an inner tube 8th and has a pin-shaped basic shape with an oval cross-section. With an oval cross-section is meant that a height H1 and a height H2 are longer than an image-related not apparent corresponding width of the oval cross-section. Furthermore, the inventive shaft instrument S a distal end D and a proximal end P (please refer 2 ), with the distal end D a cutting mouth 1 includes and the proximal end P for inclusion in the handle 5 suitable is. The inventive shaft instrument S or the outer tube 9 and accordingly also the inner tube 8th tapers towards the distal end D of the shaft instrument S in an area called a cone 14.1 of the outer tube 9 is trained.

The cutting mouth 1 is through a section of the outer tube 9 with a recess 21 at the distal end D of the shaft instrument S as well as in the outer tube 9 guided inner tube 8th shaped. The area of the outer tube 9 with the recess 21 is trained thickened. In the 1 is the inner tube 8th only slightly in the area of the recess 21 of the outer tube 9 to see. The outer tube 9 and the inner tube 8th are in a rest position or a starting position. The cutting mouth 1 it is open.

In 2 is the inventive shaft instrument S without the handle 5 represented, whereby a connection 6 of the inner tube 8th at the proximal end P of the shaft instrument S is apparent. About this connection 6 can connect to the connector 15 inside the handle 5 getting produced. The connection 6 stands in the direction of the distal end D of the shaft instrument S with the inner tube 8th or a suction channel 17 of the shaft instrument S in conjunction and can by inserting into the handle 5 towards the proximal end P of the shaft instrument S with the connection element 15 be actively connected. About the connection element 15 of the handle 5 A suction function is made possible by connecting to an external medical pump. Furthermore, a rinsing function in the connection element 15 integrated, which allows liquids, such as water, in the inner tube 8th or the suction channel 17 to initiate the suction function.

In the area of the proximal end P of the shaft instrument S has the outer tube 9 a recess 20 on. This recess 20 gives a part of the inner tube 8th free. In this shared area of the inner tube 8th are two opposing bolt bearings 18 arranged. One of these bolt bearings 18 is in 3 further visible. In these stud bearings 18 is each a bolt 19 arranged or a continuous bolt, which would mean, however, that the continuous bolt is an interior of the inner tube 8th would have to cross. With the bolts 19 is the lever 13 movably connected via a not-shown U-profile. By means of an actuation of the lever 13 towards the handle 5 an actuation of the bolt 19 in the stud bearings 18 and thus a displacement of the inner tube 8th to the outer tube 9 so that the cutting jaw 1 can be opened or closed. This possible displacement movement is indicated by the arrow F indicated. Of course, this sliding movement of the inner tube takes place 8th from the proximal end P of the shaft instrument S towards the distal end D of the shaft instrument S and vice versa.

In the handle 5 is a spring mechanism not shown in detail, which causes the lever 13 is moved to its rest position as soon as a pressure on the lever 13 to close the cutting mouth 1 subsides. That means the lever 13 only has to be operated for the cutting process.

The cutting mouth 1 is in 2 almost closed, which is why the area of the inner tube 8th in which the opposing bolts 19 are arranged, in a front, ie a distal end D of the shaft instrument S facing region of the recess 20 located. Would be the inventive shaft instrument S in its rest position with open cutting mouth 1 , would the bolts 19 in a rear area of the recess 20 located, ie in the region of the recess 20 , the proximal end P of the shaft instrument S is facing.

So that the cutting mouth 1 the almost closed position can take, is the inner tube 8th that is, as described above, with respect to the outer tube 9 towards the distal end D of the shaft instrument S or in the direction of the cutting mouth 1 been moved.

A the distal end D of the shaft instrument S facing section 22 of the inner tube 8th is formed only semi-oval and therefore runs in a kind of arc in the outer tube 9 or over the recess 21 of the outer tube 9 , The section is guided 22 of the inner tube 8th while in guide rails 3 that in a rail 12 , which in one piece from the outer tube 9 comes out, are integrated.

The section 22 of the inner tube 8th forms towards a jaw 16 a cutting edge 2 out. The guide rails 3 allow in conjunction with the rail 12 an exact alignment of the cutting edge 2 on a counter-cutting piece 4 , which is at the side of the mouth 16 is arranged in the direction of the proximal end P of the shaft instrument S is directed. Both the cutting edge 2 as well as the counter-cutting piece 4 are designed as a sharp cutting edge suitable for medical applications.

One towards the proximal end P of the shaft instrument S skillful stage of the rail 12 of the outer tube 9 serves inside the outer tube 9 as a stop 23 for a stop edge 24 of the inner tube 8th ,

The section 22 of the inner tube 8th also has numerous pressure equalization holes 10 on. The pressure compensation openings 10 serve the air intake, even if the cutting mouth 1 is still closed.

The pressure compensation openings 10 reach through the inner tube 8th , In the present embodiment are two times eight pressure equalization holes 10 includes, each eight per longitudinal side of the section 22 of the inner tube 8th arranged in a uniform and staggered pattern. Each pressure equalization opening 10 is in the present and preferred embodiment the same size and designed and arranged in the form of a slot. The long side of the slot-shaped pressure compensation openings 10 is in the distal / proximal direction, ie in the longitudinal direction of the shaft instrument S , aligned. Of course, according to the invention, other configurations and arrangements are possible as well as the number of pressure equalization openings 10 variable.

The pressure compensation openings 10 are with closed cutting mouth 1 So if the inner tube 8th in the outer tube 9 completely towards the distal end D of the shaft instrument S has been moved, in the area of the recess 21 however, they do not reach right up to the cutting edge 2 approach. Of course, this arrangement in different embodiments of the inventive shaft instrument S vary.

In 3 is the inventive shaft instrument S shown in a longitudinal section. Here is the inner tube 8th and the outer tube 9 can be seen, with both the cone 14.1 of the outer tube 9 as well as a cone 14.2 of the inner tube 8th can be seen. Here is the cone 14.2 of the inner tube 8th with respect to the tapered shape more pronounced than the cone 14.1 of the outer tube 9 , The cone 14.1 This can serve as a limitation of movement, so that the cone 14.2 or the inner tube 8th not further in the outer tube 9 can be moved as required.

The inner tube 8th also forms the suction channel 17 , which at the cutting edge 2 starts the connection 6 ends. The pressure compensation openings 10 stand with the suction channel 17 in active connection.

Furthermore, the recess 20 of the outer tube 9 and one of the bolt bearings 18 in the inner tube 8th seen.

In 4 is an enlarged view of the distal end D of the shank instrument according to the invention S seen. The cutting mouth 1 is in an open position, which is the position when not in use, ie. represents a rest position. It can be seen that at least two of the on the section 22 of the inner tube 8th included pressure equalization holes 10 lie free and not through the outer tube 9 are covered or closed. Through these exposed pressure equalization holes 10 prevents unwanted tissue from being cut into the cutting jaw before a cutting operation 1 is sucked, since the volume flow at the cutting mouth 1 through the two exposed pressure equalization holes 10 is reduced.

In this rest position are also the rail 12 and guide rails 3 can be seen, through which the section 22 led the inner tube and thus the cutting edge 2 precisely fitting the counterblade 4 the mouth tip 16 to be led.

In 5 is an enlarged view of the distal end D of the shank instrument according to the invention S with closed cutting mouth 1 shown. Here it can be seen that the cutting edge 2 in the closed position the Gegenschneidstück 4 overlaps. This overarching process, which is the actual cutting process is comparable to the scissors principle, in which the two scissor blades with their cutting only directly along each other drive along, whereby the cutting effect comes about. A similar cutting effect is achieved by the overlap of the counter-cutting piece 4 through the cutting edge 2 ,

In 6 is a so-called cutting geometry of the shank instrument according to the invention S or the cutting piece 2 and the counter-cutting piece 4 represented in their operative connection to each other. In this regard, there are three angles, viz α . β and γ shown. The angle α is preferably 20 degrees and describes the cutting geometry of the cutting piece 1 to counterblade piece 4 , The angle β describes the slope of the cutting edge of the counterblade 4 , this angle β is preferably 15 degrees. The angle γ describes the slope of the cutting edge 2 , this angle γ at preferably 35 degrees. Of course, these indicated degrees relate to the angles α . β and γ to a preferred embodiment of the invention, but may vary in other embodiments, in particular in embodiments that differ in their size.

This cutting geometry allows the cut not over the entire length of the opposing cutting surfaces or cutting the cutting edge 2 and the counter-cutting piece 4 takes place, but only at certain points according to the above-mentioned scissors principle. This reduces the cutting force required and allows a fine and clean cut with minimal necessary injury.

Otherwise, the comments on the figures apply 1 . 2 and 3 also to the 4 . 5 and 6 , This is especially true if the same features have been given the same reference numerals. Therefore, a repetition of all features already described in the first figures is omitted.

Referring to the 1 to 6 explains the operation of the inventive device as follows:

To the inventive shaft instrument S To be able to use it will be over the bolts 19 in the region of the recess 20 and the connection 6 at the proximal end P of the shaft instrument S with the handle 5 and the connection element 15 brought into operative connection. Here come different handles on the type of handle 5 in question. These may be made of metal, for example, and used again after sterilization; However, it could also be appropriate handles that consist of plastics and are intended only for medical intervention and are then given for recycling.

With the connection element 15 of the handle 5 a connection to an external medical pump is made via a hose, which is for a volume flow along the suction channel 17 from the area of the cutting mouth 1 towards the proximal end P of the shaft instrument S provides. At the same time is via the connection element 15 a liquid, such as water, in the suction channel 17 initiated, which significantly improves the suction function.

In the case of a conventional shaft instrument, there would always be the risk, during a medical intervention by the existing volume flow, that tissue would be inadvertently sucked into the region of a punch mouth and would be injured there, for example by covered blades or sharp-edged punches. To solve this problem, the present invention comprises a shaft instrument S the pressure equalization holes 10 connected to the suction channel 17 in operative connection. Of the included pressure equalization holes 10 that on the section 22 of the inner tube 8th are arranged, a part in the rest position of the cutting jaw 1 , ie in the open position of the cutting jaw 1 , not from the outer tube 9 closed or hidden. The exposed in this rest position pressure equalization holes 10 reduce by their connection to the suction channel 17 the volume flow in the area of the cutting mouth 1 , This reduction in volume flow results in the risk of inadvertent suction of tissue into the cutting jaw 1 is significantly reduced or largely excluded.

Is then the tissue to be separated or cut off and localized reached, the cutting jaw 1 of the shank instrument according to the invention S be led to the tissue. By operating the lever 13 of the handle 5 then becomes the inner tube 8th in the outer tube 9 in the direction of the distal end of the shaft instrument S moved and so the cutting mouth 1 closed. At the same time the cutting edge 2 according to the principle of paper cutting over the counter-cutting piece 4 emotional. The cutting mouth 1 is then in this moment in a closed position, which in 5 it can be seen, wherein the cutting edge 1 the counter-cutting piece 4 overlaps.

The cut tissue is located shortly after cutting within the section 22 of the inner tube 8th in the area of the pressure equalization openings 10 , By the Pressure relief openings 10 can despite closed cutting mouth 1 Sucked air and thus the cut tissue in the direction of the suction channel 17 or in the direction of the proximal end P of the shaft instrument S This is done, although the cutting mouth is still closed, which in the present embodiment only by the pressure equalization openings included 10 can be done. In a conventional shank instrument a corresponding extraction would take place only after a punch mouth would have been reopened, as previously an evolving negative pressure within a suction channel would not have allowed the suction of the die-cut tissue.

Will the lever 13 of the handle 5 relieved again, the cutting mouth opens 1 , wherein the further exposed pressure equalization openings in turn prevents other and in particular unwanted tissue in the region of the cutting jaw 1 is sucked in.

Although only a preferred embodiment of the invention has been described and illustrated, it is apparent that one skilled in the art can add numerous modifications without departing from the spirit and scope of the invention. In particular, variations in the size of individual shaft instruments according to the invention are provided, wherein in particular the cutting geometry may also change, which may lead to deviating angular masses. Furthermore, of course, the number, the shape and the arrangement of the included pressure equalization openings vary.

LIST OF REFERENCE NUMBERS

1

cutting mouth

2

cutting edge

3

guide rail

4

Against cutting piece

5

handle

6

connection

7

8th

inner tube

9

outer tube

10

Pressure relief openings

11

12

rail

13

lever

14th

cone

15

connecting element

16

Maul tip

17

suction

18

pin bearing

19

bolt

20

recess

21

recess

22

section

23

attack

24

stop edge

S

shaft instrument

H1

height

H2

height

D

distal end

P

proximal end

F

arrow

α,

corner

β

corner

γ

corner

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 202009002433 U1 [0002]
• DE 102015112716 A1 [0003]

Claims (8)

Shaft instrument for a handle (5) with a cutting jaw (1), an inner tube (8) and an outer tube (9), wherein the inner tube (8) forms a suction channel (17), characterized in that the inner tube (8) has a pressure compensation opening (10). Shank instrument after Claim 1 , characterized in that the pressure equalization opening (10) with the suction channel (17) can be brought into operative connection Shank instrument after Claim 1 or 2 , characterized in that the cutting mouth (1) is formed by a portion of the outer tube (9) with a recess (21) and the inner tube (8). Shaft instrument according to one of the preceding claims, characterized in that the inner tube (8) within the outer tube (9) is arranged to be movable. Shank instrument according to one of the preceding claims, characterized in that a cutting edge (2) emerges from the inner tube (8). Shank instrument after Claim 3 , characterized in that the cutting edge (2) cooperates with a counter cutting piece (4) according to the scissor principle. Shank instrument after Claim 5 or 6 , characterized in that an angle (α) to the cutting geometry between the cutting edge (1) and the counter-cutting piece (4) is preferably 20 degrees. Shank instrument after Claim 1 , characterized in that a rail (12) with a guide rail (3) for guiding the inner tube (8) in the region of the cutting mouth (1) from the outer tube (9) emerges and establishes a connection to a jaw tip (16).

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