Abstract:
A tool for a medical instrument includes an effecting device, a transmission rod, of which the distal end is coupled to the effecting device, for transferring at least either a force or a torque to the effecting device, and a cutting device, which, to cut tissue, is movable in a channel in the transmission rod and in the effecting device. To cut tissue, the cutting device is movable in a channel in the transmission rod and in the effecting device.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is based on a tool for a medical instrument and on a method for disassembling a tool. 
       BACKGROUND OF THE INVENTION 
       [0002]    The expectations of medical instruments, in particular of medical instruments for microinvasive interventions, increase continuously. A variety of medical instruments comprising a tool with gripping or cutting function at the distal end are already offered and are widespread. Medical devices and medical staff prefer medical instruments that can be used in the most versatile manner possible. The more versatile the manner in which the individual medical instrument can be used, the smaller is the variety of the instruments to be kept ready. Medical instruments that can be used in a versatile manner can therefore reduce the capital outlay necessary in a medical device, even with higher unit costs. Due to a small variety and a low unit number of the medical instruments to be kept ready, the costs for storing and logistics can also be reduced. In the case of microinvasive medical instruments or medical instruments for microinvasive interventions, instruments also have to be exchanged less frequently during an intervention the more versatile the manner in which the individual instrument can be used. 
       SUMMARY OF THE INVENTION 
       [0003]    The object of the present invention is to create an improved tool for a medical instrument, an improved medical instrument, and an improved method for disassembling a tool for a medical instrument. 
         [0004]    This object is achieved by the subjects of the independent claims. 
         [0005]    Developments are disclosed in the dependent claims. 
         [0006]    A tool for a medical instrument comprises an effecting device, a transfer rod, of which the distal end is coupled to the effecting device, for transferring at least either a force or a torque to the effecting device, and a cutting device, which, to cut tissue, is movable in a channel in the transmission rod and in the effecting device. 
         [0007]    The tool is provided and designed in particular for a microinvasive surgical instrument. The effecting device is in particular a pair of pincers with a plurality of mouth parts, of which at least one is movable, for gripping or squeezing tissue. Alternatively or in addition, the effecting device may have an electrosurgical function. In electrosurgery or in the case of electrosurgical measures, heat is generated in the tissue by means of a current flow and due to the electrical resistance of tissue (Joule&#39;s law). The current flow is localized as accurately as possible due to the shape and arrangement of the electrodes used in this instance. The tissue through which current has flowed is cauterized or destroyed by the heat produced. Tissue can thus be stuck together or closed for example, and hemorrhages stopped. Generally, high-frequency alternating currents are used in electrosurgery in order to avoid a stimulation of nerves and other undesired side effects. The terms “electrosurgery” and “HF surgery” are often used synonymously. A further term, often used synonymously, is electrocauterization. 
         [0008]    The effecting device and the cutting device are two non-identical devices that in particular are designed to act in different ways on tissue and therefore have different features and components, at least in part. Even if the effecting device is a gripping device for example which is designed to hold tissue during a cutting operation by means of the cutting device, the effecting device and the cutting device have two potentially mutually supplementing, yet different, functions. In particular, the cutting device and the effecting device have no common components. The cutting device can be designed as a completely independent component that can be separated without destruction from the effecting device. The effecting device is in particular designed to have and to exert its provided function and action even in the absence of the cutting device. 
         [0009]    The tool is in particular designed for releasable mechanical connection to a distal end of an outer shaft. The transmission rod is in particular designed for arrangement in the outer shaft. The transmission rod can be straight or curved, rigid or flexible. If the tool is provided and designed to be combined with a curved or flexible outer shaft to form a medical instrument, the transmission rod is flexible or resilient in particular at least in curved or curvable regions of the outer shaft. The proximal end of the transmission rod is in particular designed for coupling to a handling device, in particular to a lever or another actuation device on a handling device. 
         [0010]    The channel in which the cutting device is movable extends in particular in the longitudinal direction of the tool. The longitudinal direction of the tool is in particular identical to the longitudinal direction of a distal end of an outer shaft when the tool is connected to the outer shaft. The channel extends in particular substantially as far as the distal end of the effecting device. For example in the case of an effecting device designed as a gripping device comprising two mouth parts, the channel extends preferably over the majority (in particular at least 80%) of the length of the mouth parts. 
         [0011]    A tool having the described features can be used in a particularly versatile manner. For example, it can be used both to grip, prepare and coagulate tissue by means of the effecting device and also to subsequently sever the tissue by means of the cutting device. This makes it possible to perform complex medical interventions without exchanging the medical instrument or with less frequent exchanges of the medical instrument in the event of an intervention. 
         [0012]    In the case of a tool as is described here, the transmission rod is coupled in particular to a pivotable mouth part of the tool. 
         [0013]    In particular, the distal of the transmission rod is coupled to one, two or more pivotable mouth parts of the tool in such a way that a movement of the transmission rod in the longitudinal direction thereof or in the longitudinal direction of an outer shaft, to which the tool is mechanically connected, is accompanied by a pivoting of the pivotable mouth part(s) about pivot axes perpendicular to the longitudinal axis. 
         [0014]    In the case of a tool as is described here, the effecting device in particular comprises two or more mouth parts electrically insulated from one another, wherein a first of the mouth parts is electrically conductively connected to the transfer rod, and wherein a second of the mouth parts is electrically conductively connected or connectable to an outer shaft. 
         [0015]    With two or more mouth parts electrically insulated from one another, a use as a bipolar electrosurgical instrument is possible, with which a high-frequency alternating current for coagulating or cauterizing tissue flows almost exclusively in the small and comparatively well-defined space between the mouth parts. The tool can therefore be used for example initially to electrosurgically close a vessel or another hollow organ and immediately thereafter to sever said vessel or other hollow organ. 
         [0016]    In the case of a tool as is described here, the cutting device in particular is designed to cut with a movement in the direction parallel to the longitudinal axis of the tool. 
         [0017]    In particular, the cutting device comprises at its distal end an at least partly distally directed (in particular not parallel to the longitudinal axis and to the provided direction of movement) blade. By displacing the cutting device from a proximal position to a distal position, tissue can be cut or severed and is held for example by means of the effecting device. 
         [0018]    In the case of a tool as is described here, the channel in particular comprises a groove in the transfer rod, wherein at least either the cutting device or the groove is designed such that a movement of the cutting device in proximal direction accompanies a lifting out of the cutting device from the groove. 
         [0019]    In particular, the cutting device and the groove are designed such that the proximal end of the cutting device is lifted out from the groove when it approaches the proximal end of the groove or reaches the proximal end of the groove. This may enable a removal of the cutting device from the groove by means of a simple movement of the cutting device in proximal direction. 
         [0020]    In the case of a tool as is described here, the channel in particular comprises a groove, in particular a groove in the transfer rod, wherein the groove has a continuously reducing depth in proximal direction in a region close to the proximal end of the groove. 
         [0021]    In particular, the bottom or the base of the groove is ramp-shaped with a constant or varying incline. 
         [0022]    Alternatively or in addition, the cutting device comprises at its proximal end a ramp-shaped region, which can slide over the edge of the groove at the proximal end thereof, wherein a movement of the cutting device in proximal direction accompanies a lifting out of the cutting device from the groove. 
         [0023]    A tool as is described here in particular comprises a coupling device for releasable mechanical connection of the tool to a distal end of an outer shaft, wherein, in all positions provided for the cutting device during the use of the tool, the proximal end of the cutting device is arranged proximally of the coupling device and the distal end of the cutting device is arranged distally of the coupling device. 
         [0024]    The cutting device in particular comprises a coupling device for releasable mechanical connection of the cutting device to a distal end of an inner shaft or a transfer device. The arrangement of the proximal end of the cutting device and of its coupling device proximally of the coupling device provided for releasable mechanical connection of the tool to an outer shaft can be advantageous in terms of the required and available installation space and therefore in terms of the design and manufacturing effort and of the degree of miniaturization achievable. 
         [0025]    The cutting device is in particular formed in one piece, and for example is produced from a single piece of metal. 
         [0026]    In the case of a tool as is described here, the cutting device in particular comprises a bar-shaped region between its proximal end and its distal end. 
         [0027]    The bar-shaped region of the cutting device in particular has a rectangular cross section and in particular is designed to be arranged completely within the channel. The bar-shaped region is in particular arranged completely within the aforementioned groove in the transmission rod with the provided use and arrangement of the cutting device, that is to say does not protrude or does not protrude considerably beyond the edges of the groove. 
         [0028]    In the case of a tool as is described here, the cutting device in particular comprises a protrusion, which protrudes in a direction perpendicular to the provided direction of movement of the cutting device. 
         [0029]    The protrusion is in particular arranged at or close to the proximal end of the cutting device and in particular defines the proximal end of the aforementioned bar-shaped region of the cutting device since the protrusion constitutes a deviation from the bar-shaped design. With an arrangement of the cutting device in the aforementioned groove in the transfer rod, merely the protrusion protrudes from the groove and forms a coupling device for releasable, in particular interlocked, mechanical connection of the cutting device to a distal end of an inner shaft or another transfer device. Furthermore, the protrusion when disassembling the tool can be used to shift the cutting device manually in the proximal direction in order to lift it out from the groove, as described above. 
         [0030]    In the case of a tool as is described here, the cutting device is in particular arranged completely in the channel, apart from the protrusion, in a position provided during the use of the tool. 
         [0031]    A medical instrument comprises a tool as is described here and an inner shaft, of which the distal end is releasably mechanically connectable to the cutting device. 
         [0032]    In the case of a medical instrument as is described here, the inner shaft in particular at its distal end comprises an L-shaped slit or an L-shaped groove for receiving the protrusion on the cutting device. 
         [0033]    The L-shaped slit or the L-shaped groove at the distal end of the inner shaft on the one hand and the protrusion on the cutting device on the other hand form corresponding bayonet coupling devices. The inner shaft can therefore be coupled or mechanically connected to the cutting device by means of an axial and a subsequent rotary movement relative to the tool and the transfer rod, and can be separated again from said cutting device by means of a reversed relative movement. 
         [0034]    In the case of a method for disassembling a tool for a medical instrument, wherein the tool comprises an effecting device and a cutting device in a channel, a mechanical connection between a distal end of a transfer device and the cutting device is separated and the cutting device is moved in proximal direction relative to the tool, wherein the cutting device is lifted out from the channel. 
         [0035]    The method is applicable in particular to a tool having the features described here. The mechanical connection between the distal end of the transfer device and the cutting device (in particular the proximal end of the cutting device) is achieved without destruction or reversibly. To this end, the distal end of the transfer device and the cutting device (in particular the proximal end of the cutting device) comprise coupling devices corresponding to one another. 
         [0036]    When the cutting device is moved in proximal direction, the at least partial lifting out of the cutting device from the channel occurs automatically or independently due to features of the cutting device and/or the channel. When the cutting device is lifted out from the channel, in particular the proximal end of the cutting device is lifted out of a groove in a transfer rod. In so doing, in particular the proximal end of the cutting device slides over a ramp-shaped region at the proximal end of the groove and/or a ramp-shaped region at the proximal end of the cutting device at a proximal edge of the groove. 
         [0037]    In order to move the cutting device, the proximal end of the cutting device, in particular the aforementioned protrusion, can be gripped manually or by means of an aid. For example, a finger is pressed onto the protrusion and the protrusion is driven in proximal direction by a movement of the finger due to interlocked and/or force-locked engagement. 
         [0038]    The method described here for disassembling a tool can be useful in the event of post-processing after use of a medical instrument comprising the tool and in the event of preparation for the cleaning and sterilizing of the tool and therefore also for the preparation of a further use within the scope of a diagnostic, surgical or therapeutic procedure. The method for disassembly however does not itself constitute a diagnostic, surgical or therapeutic method. 
         [0039]    In the case of a method as is described here, a distal end of an outer shaft is separated from the tool, in particular before the separation of the mechanical connection between the distal end of the transfer device and the cutting device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]    Embodiments will be explained in greater detail hereinafter on the basis of the accompanying figures, in which: 
           [0041]      FIG. 1  shows a schematic illustration of a medical instrument; 
           [0042]      FIG. 2  shows a schematic axonometric illustration of a gripping device for a medical instrument; 
           [0043]      FIG. 3  shows a schematic axonometric illustration of a cutting device; 
           [0044]      FIG. 4  shows a further schematic axonometric illustration of the devices from  FIGS. 2 and 3 ; 
           [0045]      FIG. 5  shows a further schematic axonometric illustration of the devices from  FIGS. 2 to 4 ; 
           [0046]      FIG. 6  shows a schematic sectional illustration of the tool from  FIGS. 2 ,  4  and  5 ; 
           [0047]      FIG. 7  shows a further schematic sectional illustration of the tool from  FIGS. 2 and 4  to  6 ; 
           [0048]      FIG. 8  shows a further schematic sectional illustration of the tool from  FIGS. 2 and 4  to  7 ; 
           [0049]      FIG. 9  shows a further schematic sectional illustration of the tool from  FIGS. 2 and 4  to  8 ; 
           [0050]      FIG. 10  shows a schematic flow diagram of a method for disassembling a tool. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0051]      FIG. 1  shows a schematic illustration of a medical instrument  10  having a proximal end  11  and a distal end  12 . At the proximal end  11 , the medical instrument  10  comprises a handling device  18 , which is designed to be grasped by the hand of medical staff and to receive manually generated forces and torques. To this end, the handling device  18  in particular comprises a plurality of grip parts, which are movable at least in part relative to one another. 
         [0052]    A shaft  20  extends from the proximal end  11  or the handling device  18  to the distal end  12  of the medical instrument  10 . The shaft  20  comprises a proximal end  21  and a distal end  22 . The proximal end  21  of the shaft  20  is mechanically connected to the handling device  18 , in particular is arranged in a recess having a shaping corresponding to the proximal end  21  of the shaft  20 , where it is locked in an interlocking manner by means of a locking device  19 . 
         [0053]    The shaft  20  comprises a longitudinal axis  28 . In the case of a circular cylindrical shaping of the shaft  20 , the longitudinal axis  28  in particular is the axis of symmetry of the lateral surface of the shaft  20 . The inner structure of the shaft  20  described below can be rotationally symmetrical about the longitudinal axis  28 . The shaft  20  can be straight or, by contrast with the illustration in  FIG. 1 , curved, rigid or flexible. If the shaft  20  is curved or flexible at least in some portions, the longitudinal axis hereinafter means the longitudinal axis of the shaft  20  at its proximal end  21  or at its distal end  22 . The shaft  20  is in particular also rotatable about its longitudinal axis  28  in the state locked in the handling device  18 . 
         [0054]    The distal end  22  of the shaft  20  is connected to a tool, which comprises a gripping device  30  and a cutting device  50 . The gripping device  30  in particular comprises two gripping jaws, of which at least one is pivotable about a pivot axis perpendicular to the drawing plane of  FIG. 1 . In the example shown in  FIG. 1 , both gripping jaws are pivotable between open positions, which are illustrated in  FIG. 1  by solid lines, and closed positions, which are illustrated in  FIG. 1  by dashed lines. As indicated in  FIG. 1  by an arrow, the cutting device  50  is movable in a direction parallel to the longitudinal axis  28 , more specifically both when the mouth parts of the gripping device adopt their open positions and when they adopt their closed positions. 
         [0055]    Exemplary embodiments of the tool  30 ,  50  and its releasable mechanical connection to an outer shaft, an inner shaft and a transmission rod are presented hereinafter. The tools, outer shafts, inner shafts and transfer rods presented hereinafter may be designed and used to form a medical instrument having the features illustrated with reference to  FIG. 1  and/or having other features. 
         [0056]      FIG. 2  shows a schematic axonometric illustration of a gripping device  30 , which is provided and designed to form a medical instrument as is presented above with reference to  FIG. 1 . The gripping device  30  comprises a proximal end  31  and two mouth parts  32 ,  34 , which form the distal end of the gripping device  30 . In contrast to the gripping device indicated in  FIG. 1 , the gripping device  30  illustrated in  FIG. 2  comprises a stationary mouth part  32  and a pivotable mouth part  34 . Close to the proximal end  31 , the gripping device  30  comprises two symmetrically arranged bayonet claws or catches  37 , of which one is arranged on a side facing away from the viewer and therefore is largely obscured. 
         [0057]    The gripping device  30  is mechanically connected to a transmission rod  40 . The transmission rod  40  is movable relative to the gripping device  30 , in particular relative to the proximal end  31  and to the stationary mouth part  32  in the axial direction, that is to say parallel to the longitudinal axis of the transmission rod  40  and to the longitudinal axis  28  of the shaft  20  (see  FIG. 1 ), within a predetermined interval. The distal end of the transmission rod  40  arranged within the gripping device  30  and therefore not visible in  FIG. 2  is coupled to the pivotable mouth part  34  in such a way that an axial movement of the transmission rod  40  accompanies a pivoting movement of the pivotable mouth part  34 . In the transmission rod  40 , a groove  45  is provided, which in particular has a narrow and deep rectangular cross section. The groove  45  in the transmission rod  40  is continued at the distal end thereof (not visible in  FIG. 2 ) by a cross section corresponding to a channel and extending between the mouth parts  32 ,  34  almost as far as the distal ends thereof. 
         [0058]    Parts of the gripping device  30 , in particular the catches  37  and also the transmission rod  40  are manufactured from stainless steel or another metal. The catches  37  and the transmission rod  40  are electrically insulated from one another. The mouth parts  32 ,  34  comprise metal and therefore electrically conductive grip areas, which are electrically insulated from one another when they do not bear against one another, as shown in  FIG. 2 . The catches  37  and the transmission rod  40  are each electrically conductively connected to the grip area of a mouthpart  32 ,  34 . In particular, the catches  37  are electrically conductively connected to the grip area of the fixed mouth part  32 , and the transmission rod  40  is electrically conductively connected to the grip area of the pivotable mouth part  34 . 
         [0059]      FIG. 3  shows a schematic axonometric illustration of a cutting device  50  having a proximal end  51  and a distal end  52 . At the distal end  52 , the cutting device  50  comprises a blade  53 . At the proximal end, the cutting device  50  comprises a protrusion  56 . Between the proximal end  51  and the distal end  52 , the cutting device comprises a bar-shaped region  54 , which basically has the form of a strip-shaped plate or of a bar with a rectangular cross section. 
         [0060]    Between the protrusion  56  at the proximal end  51  and the blade  53  at the distal end  52 , the cross section of the cutting device  50  corresponds substantially to the cross section of the groove  45  in the transmission rod  40  (see  FIG. 2 ), and therefore the cutting device  50 , apart from the protrusion  56 , can be received completely by the groove  45  in the transmission rod  40  and can be guided therein with little play and little friction and can be displaceable in the longitudinal direction of the transmission rod  40  and of the cutting device  50 . The protrusion  56  is provided to protrude from the groove  45  in the transmission rod  40 . 
         [0061]      FIG. 4  shows a further schematic axonometric illustration of the gripping device from  FIG. 2  and of the cutting device  50  from  FIG. 3 . In the illustration in  FIG. 4 , the cutting device  50  is arranged in the groove  45  in the transmission rod  40  (see  FIG. 2 ). The distal end  52  of the cutting device  50  (see  FIG. 3 ) is arranged here in the gripping device and in particular between the mouth parts  32 ,  34 . The protrusion  56  protrudes from the groove  45 . 
         [0062]    In  FIG. 4 , an inner shaft  60  is also shown, which has substantially a tubular or circular cylindrical shaping. At its distal end  62 , the inner shaft  60  comprises an L-shaped slit with an axial portion  63  or a portion  63  extending in the axial direction and a circumferential portion  64  or a portion  64  extending in the circumferential direction. The width of the axial portion  63  to be measured in the circumferential direction and the width of the circumferential portion  64  of the L-shaped slit to be measured in the axial direction are matched to the dimensions of the protrusion  56  on the cutting device  50 . 
         [0063]    Once the transmission rod  40  has been introduced into the inner shaft  60 , the protrusion  56  can be introduced through the axial portion  63  until in the circumferential portion  64  by means of a relative movement in the axial direction. When the protrusion  56  on the cutting device  50  is located in the circumferential portion  64  of the L-shaped slit at the distal end  62  of the inner shaft  60 , the inner shaft  60  can be rotated relative to the gripping device  30 , the transmission rod  40  and the cutting device  50  in a first direction  91  until the configuration shown in  FIG. 4  has been reached. 
         [0064]    In the relative positioning of the cutting device  50  and inner shaft  60  shown in  FIG. 4 , the cutting device  50  and inner shaft  60  are coupled rigidly to one another (apart from play) in terms of axial movements. An axial movement of the inner shaft  60  therefore accompanies a corresponding axial movement of the cutting device  50 . A movement of the blade  53  at the distal end  52  of the cutting device  50  (see  FIG. 3 ) in the aforementioned channel (not visible in the figures) between the mouth parts  32 ,  34  can therefore be implemented by means of the inner shaft  60 , for example in order to sever tissue gripped by the mouth parts  32 ,  34  after an electrocauterization procedure. 
         [0065]    The inner shaft  60  comprises an insulating sheath  69 , of which the distal edge is arranged close to the L-shaped slit  63 ,  64 , and which may extend until close to the proximal end of the inner shaft  60 . 
         [0066]      FIG. 5  shows a further schematic axonometric illustration of the gripping device  30  from  FIGS. 2 and 4 . The illustration in  FIG. 5  differs from the illustration in  FIGS. 2 and 4  in that an outer shaft  70  is coupled to the gripping device  30 . The outer shaft  70  comprises at its distal end  72  two symmetrically arranged L-shaped slits, each having an axial portion  73  and a circumferential portion  74 . One of the L-shaped slits is arranged on a side of the outer shaft  70  facing away from the viewer and therefore is not visible in  FIG. 5 . 
         [0067]    The width of the axial portions  73  to be measured in the circumferential direction and the width of the circumferential portions  74  of the L-shaped slits to be measured in the axial direction are matched to the dimensions of the catches  37  on the gripping device  30 . As a result of a movement of the outer shaft  70  in the axial direction and a subsequent rotation relative to the gripping device  30 , the catches  37  can be introduced through the axial portions  73  into the circumferential portions  74  until the configuration shown in  FIG. 5  has been reached. In the configuration or arrangement shown in  FIG. 5  of the catches  37  in the circumferential portions  74  of the L-shaped slits at the distal end  72  of the outer shaft  70 , the outer shaft  70  and the gripping device  30  are rigidly coupled to one another (apart from play) with regard to axial forces and movements. 
         [0068]    By comparison of  FIGS. 4 and 5 , it can be seen that the circumferential portions  64 ,  74  of the L-shaped slits at the distal ends  62 ,  72  of the inner shaft  60  on the one hand and of the outer shaft  70  on the other hand extend in opposite directions from the axial portions  63 ,  73 . Accordingly, the direction  92  in which the outer shaft  70  is to be rotated relative to the gripping device  30  in order to reach the coupled configuration shown in  FIG. 5  is opposite to the direction  91  in which the inner shaft  60  is to be rotated relative to the gripping device  30  and relative to the cutting device  50  in order to reach the coupled configuration shown in  FIG. 4 . 
         [0069]      FIG. 6  shows a schematic sectional illustration of the tool from  FIGS. 2 ,  4  and  5 . The illustrated sectional plane contains the longitudinal axis  28  (see  FIG. 1 ). 
         [0070]    The gripping device  30  comprises a main body  81 , which has an electrically insulating material and can be joined from a plurality of elements. The main body  81  extends from the proximal end  31  of the gripping device  30  to the proximal end thereof and in particular forms the stationary mouth part  32 . The stationary mouth part  32  comprises a grip area insert  82  made of metal. The catches  37  are components of a sleeve-shaped metal component that is connected to the grip area insert  82  on the stationary mouth part  32  by means of a wire arranged at least in part in the main body  81  of the gripping device  30  or by means of another electrically conductive connection  83 . 
         [0071]    The pivotable mouth part  34  has a metal grip area insert  84 . In the main body  81 , a metal bearing component  86  is arranged, which is electrically insulated from the catches  37  and the grip area insert  82  of the stationary mouthpart  32  by means of the main body  81 . A journal  88  is rigidly connected to the pivotable mouth part  34  and is mounted in the bearing component  86  so as to be rotatable about a pivot axis perpendicular to the sectional plane in  FIG. 6 . The journal  88  and a web-shaped or plate-shaped region of the bearing component  86 , said region being arranged parallel to the sectional plane in  FIG. 6 , are arranged behind the sectional plane in  FIG. 6  as considered by the viewer. Symmetrically about the sectional plane in  FIG. 6 , a further journal is arranged on the pivotable mouth part  34  and a further plate-shaped region of the bearing component  86 , in which the further journal is mounted, is arranged before the sectional plane of  FIG. 6  or between the sectional plane and the viewer. The bearing component  86  and the journal  88  define the pivot axis of the pivotable mouth part  34 , said pivot axis being arranged perpendicular to the sectional plane of  FIG. 6 . The journals  88  are electrically conductively connected to the grip area insert  84  on the pivotable mouth part  34 . In particular, the journals  88  are each formed in one piece with a strut extending parallel to the pivotable mouth part  34 , wherein the struts and the grip area insert  84  are welded, soldered, screwed or otherwise joined. 
         [0072]    The transmission rod  40  protrudes from the proximal end  31  of the gripping device  30  into the main body  81 . The transmission rod  40  is mechanically coupled to the pivotable mouth part  34  in such a way (not visible in  FIG. 6 ) that a movement in translation of the transmission rod  40  parallel to the longitudinal axis  28  accompanies a pivoting movement of the pivotable mouth part  34  about the pivot axis, defined by the journal  88 , perpendicular to the sectional plane of  FIG. 6 . In the distal position of the transmission rod  40  shown in  FIG. 6 , the pivotable mouth part  34  adopts an open position or a position distanced from the stationary mouth part  32 . 
         [0073]    The transmission rod  40  formed from a metal material is electrically conductively connected to the journal  88  and the grip area insert  84  on the pivotable mouth part  34 . The transmission rod  40  is electrically insulated by the main body  81  of the gripping device  30  from the catches  37  and from the grip area insert  82  of the stationary mouth part  32 . 
         [0074]    The cutting device  50  is arranged in a groove in the transmission rod  40 , which is only provided with a reference sign in  FIGS. 8 and 9 , and in a groove  87  in the bearing component  86 . The groove  87  in the bearing component  86  is defined in a direction perpendicular to the sectional plane in  FIG. 6  by the aforementioned plate-shaped regions of the bearing component  86 , in which the journals  88  of the pivotable mouth part  34  are mounted, or is formed by the gap between the two plate-shaped components. In an extension of the groove in the transmission rod  40  and of the groove  87  in the bearing component  86  in the distal direction, a groove  33  is provided in the stationary mouth part  32 , in particular in the grip area insert  82  of the stationary mouth part  32 , and a groove  35  is provided in the pivotable mouth part  34 , in particular in the grip area insert  84  of the pivotable mouthpart  34 . 
         [0075]    Cross sections of electrically conductive components, in particular of the catches  37 , the transmission rod  40 , the cutting device  50 , the grip area inserts  82 ,  84  and the bearing component  86 , are illustrated in  FIG. 6  by dense hatching. Cross sections of electrically insulating components, in particular of the main body  81 , are illustrated by wide hatchings. As already mentioned, an electrically conductive connection exists between the transmission rod  40  and the grip area insert  84  on the pivotable mouth part  34  via the journals  88  and the aforementioned struts, and an electrically conductive connection  83  exists between the catches  37  and the grip area insert  82  on the stationary mouth part  32 . The catches  37  and the grip area insert  84  on the pivotable mouth part  34  are electrically insulated from the transmission rod  40  and the grip area insert  82  on the stationary mouth part  32 , provided the grip area inserts  82 ,  84  do not contact one another. The gripping device  30  can therefore be used as a bipolar electrosurgical instrument, wherein one pole or one potential is fed via the transmission rod  40  and the other pole or the other potential is fed via an outer shaft and the catches  37 . 
         [0076]      FIG. 7  shows a further schematic sectional illustration of the gripping device  30  form  FIGS. 2 and 4  to  6 . The sectional plane of  FIG. 7  corresponds to the sectional planes in  FIG. 6 . In  FIG. 7 , the transmission rod  40  is shown in a proximal position, and the pivotable mouth part  34  is shown in a corresponding closed position or in a position bearing against the stationary mouth part  32 . In  FIG. 7 , tissue (not shown) between the mouth parts  32 ,  34  can be coagulated or cauterized by means of a current flow between the grip area inserts  82 ,  84 . 
         [0077]    It can be seen in  FIG. 7  that the grooves  33 ,  35  in the mouth parts  32 ,  34  form an extension of the groove in the transmission rod  40  and of the groove  87  in the bearing component  86  in the distal direction. The groove in the transmission rod  40 , the groove  87  in the bearing component  86 , and the grooves  33 ,  35  in the mouth parts  32 ,  34  form a channel, in which the cutting device  50  is guided with little play and little friction and is movable or displaceable between a proximal position (in particular the position shown in  FIGS. 6 and 7 ) and a distal position. To this end, in particular the groove in the transmission rod  40 , the groove  87  in the bearing component  86 , and the grooves  33 ,  35  in the mouth parts  32 ,  34  have cross sections (in sectional planes perpendicular to the sectional planes of  FIGS. 6 and 7  and perpendicular to the longitudinal axis  28 ) that correspond to the cross section of the cutting device  50 , in particular of the bar-shaped region  54  thereof, or that are only slightly larger than said cross section of the cutting device. 
         [0078]      FIG. 8  shows a further schematic sectional illustration of the gripping device  30  from  FIGS. 2 and 4  to  7 . The sectional plane of  FIG. 8  corresponds to the sectional planes of  FIGS. 6 and 7 . As in  FIG. 7 , the transmission rod  40  in  FIG. 8  is also shown in a proximal position and the pivotable mouth part  34  is also shown in a closed position. 
         [0079]    In  FIG. 8 , the cutting device  50  is shown in a distal position. The groove  45  in the transmission rod  40  is thus visible proximally of the cutting device  50 . In the distal position of the cutting device  50  shown in  FIG. 8 , said cutting device fills the grooves  33 ,  35  in the mouth parts  32 ,  34  almost completely. The blade  53  on the cutting device  50  is located directly proximally of the distal ends of the mouth parts  32 ,  34 . When the cutting device is moved from the proximal position shown in  FIG. 7  to the distal position shown in  FIG. 8 , the blade  53  of the cutting device  50  severs tissue (not illustrated in the figures) between the mouth parts  32 ,  34 , in particular after electrocauterization of the tissue. 
         [0080]    At the proximal end  51  of the cutting device  50 , the protrusion  56  also illustrated in  FIGS. 3 and 4  is visible and can be releasably coupled in an interlocking manner to the distal end  62  of an inner shaft  60  (see  FIG. 4 ) and enables a movement of the cutting device  50  between the positions shown in  FIGS. 7 and 8  by means of the inner shaft  60 . 
         [0081]      FIG. 9  shows a further schematic sectional illustration, of which the sectional plane corresponds to the sectional planes in  FIGS. 6 to 8 . The detail shown in  FIG. 9  is shifted in proximal direction compared to the detail shown in  FIGS. 6 to 8 . The proximal end  31  of the gripping device  30  (see  FIGS. 6 to 8 ) is visible at the distal (left-hand) edge of the image. An insulating sheath  49  on the transmission rod  40  is visible at the proximal (right-hand) edge of the image. 
         [0082]    The groove  45  in the transmission rod  40  comprises at its proximal end a ramp-shaped region  43  with an increasing incline. In the ramp-shaped region  43 , the depth of the groove decreases continuously or steadily. The cutting device  50  is illustrated twice in  FIG. 9 . The position of the cutting device  50  illustrated merely by dashed contours is arranged proximally far of the position illustrated in  FIGS. 6 and 7 , but completely within the groove  45  in the transmission rod  40  apart from the protrusion  56 . If the cutting device  50  is shifted further in proximal direction, the cutting device  50  adopts the position illustrated in  FIG. 9  in solid lines. In this position, the proximal end  51  of the cutting device  50  is lifted out partially from the groove  45  due to the ramp-shaped region  43  at the proximal end of the groove  45 . 
         [0083]    The cutting device  50  can therefore be lifted out from the groove  45  and then removed therefrom by merely displacing the cutting device  50  (for example by means of a corresponding application of force of a finger on the protrusion  56 ). Since, here, the proximal end  51  of the cutting device  50  is initially lifted out from the groove and the cutting device can then be grasped at the proximal end  51 , the risk of damage to the blade  53  is low. 
         [0084]      FIG. 10  shows a schematic flow diagram of a method for disassembling a tool for a medical instrument. The method can be carried out in particular on a tool having the features presented above with reference to  FIGS. 1 to 9 , but can also be applied to tools having other features. To simplify comprehension, reference signs from  FIGS. 1 to 9  will be used hereinafter by way of example. 
         [0085]    In a first step  101 , the tool  30 ,  50  is separated or released from the distal end  72  of an outer shaft  70 , in particular by releasing a bayonet coupling. In a second step  102 , the tool  30 ,  50  is separated or released from a distal end  62  of an inner shaft  60  or another transfer device. Here, a mechanical connection between the distal end  62  of the transfer device  60  and a cutting device  50  is released in particular. In a third step  103 , the proximal end  51  of the cutting device  50  is grasped. In a fourth step  104 , the cutting device  50  is moved in proximal direction relative to other components of the tool. The third step  103  and the fourth step  104  are in particular carried out by placing a finger on the protrusion  56  on the cutting device  50 , pressing against said protrusion and using the finger to slide the protrusion  56  and the cutting device  50  in proximal direction. As the cutting device  50  is moved in proximal direction  104 , the cutting device  50  is lifted out from a groove  45  in a fifth step  105 . This occurs in particular when the proximal end of the groove  45  is reached. 
       REFERENCE SIGNS 
       [0000]    
       
           10  medical instrument 
           11  proximal end of the medical instrument  10   
           12  distal end of the medical instrument  10   
           18  handling device at the proximal end  11  of the medical instrument  10   
           19  locking device on the handling device  18   
           20  shaft of the medical instrument  10   
           21  proximal end of the shaft  20   
           22  distal end of the shaft  20   
           28  longitudinal axis of the shaft  20   
           30  gripping device at the distal end  12  of the medical instrument  10   
           31  proximal end of the gripping device  30   
           32  stationary mouth part of the gripping device  30   
           33  groove in the stationary mouth part  32  of the gripping device  30   
           34  pivotable mouth part of the gripping device  30   
           35  groove in the pivotable mouth part  34  of the gripping device  30   
           37  catch at the proximal end  31  of the gripping device  30   
           40  transmission rod of the medical instrument  10   
           43  ramp-shaped region at the proximal end of the groove  45   
           45  groove in the transmission rod  40   
           49  insulating sheath on the transmission rod  40   
           50  cutting device at the distal end  12  of the medical instrument  10   
           51  proximal end of the cutting device  50   
           52  distal end of the cutting device  50   
           53  blade on the cutting device  50   
           54  bar-shaped region of the cutting device  50   
           56  protrusion at the proximal end  51  of the cutting device  50   
           60  inner shaft of the medical instrument  10   
           62  distal end of the inner shaft  60   
           63  axial portion of an L-shaped slit at the distal end  62   
           64  circumferential portion of an L-shaped slit at the distal end  62   
           69  insulating sheath on the inner shaft  60   
           70  outer shaft of the medical instrument  10   
           72  distal end of the outer shaft  70   
           73  axial portion of an L-shaped slit at the distal end  72   
           74  circumferential portion of an L-shaped slit at the distal end  72   
           81  main body of the gripping device  30   
           82  grip area insert on the stationary mouth part  32   
           83  conductive connection between the catch  37  and grip area insert  82  on the stationary mouth part  32   
           84  grip area insert on the pivotable mouth part  34   
           86  bearing component 
           87  groove in the bearing component  86   
           88  journal on the pivotable mouth part  34   
           101  first step (separating the tool from the outer shaft) 
           102  second step (separating the tool from the inner shaft) 
           103  third step (gripping the cutting device) 
           104  fourth step (moving the cutting device in proximal direction) 
           105  fifth step (lifting out the cutting device)