Abstract:
A medical instrument includes an outer shaft, a manipulation device at the proximal end of the outer shaft, a tool at the distal end of the outer shaft, with a first effecting device for a first function and a second effecting device for a second function, a first transmission device in the outer shaft for transmitting at least either a force or a torque for controlling the first effecting device, and a second transmission device in the outer shaft for transmitting at least either a force or a torque for controlling the second effecting device. The outer shaft is at least either curved or able to be curved or has a pivot joint. The first transmission device and the second transmission device are each designed to be flexible at least in sections.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a medical instrument for micro-invasive surgical applications. 
       BACKGROUND OF THE INVENTION 
       [0002]    The expectations placed on medical instruments for micro-invasive interventions are constantly increasing. Medical instruments having a tool with a grasping or cutting function at the distal end, where the tool is rotatable about the longitudinal axis of the shaft, are already widely available in many forms. The grasping or cutting function and the rotation of the tool can be controlled, for example, by a single transmission rod, which transmits longitudinal forces and torques. Moreover, in recent times, the shaft can be angled proximally of the tool, and, in order to control this angle, a second transmission element can be provided in the shaft of the medical instrument, for example a second transmission rod. 
       SUMMARY OF THE INVENTION 
       [0003]    An object of the present invention is to make available an improved medical instrument, in particular a medical instrument that is more versatile and can be better adapted to different tasks and uses. 
         [0004]    This object is achieved by the subject matter of the independent claims. 
         [0005]    Developments are set forth in the dependent claims. 
         [0006]    A medical instrument comprises an outer shaft, a manipulation device at the proximal end of the outer shaft, a tool at the distal end of the outer shaft, with a first effecting device for a first function and a second effecting device for a second function, a first transmission device in the outer shaft for transmitting at least either a force or a torque for controlling the first effecting device, and a second transmission device in the outer shaft for transmitting at least either a force or a torque for controlling the second effecting device, wherein the outer shaft is at least either curved or able to be curved or has a pivot joint, and wherein the first transmission device and the second transmission device are each designed to be flexible at least in sections. 
         [0007]    The medical instrument is in particular a medical instrument for micro-invasive surgical applications. The second effecting device is designed for a second function that is different than the first function and that can be controlled independently of the first function. For this purpose, the first effecting device can be controlled by means of the first transmission device, and the second effecting device can be controlled independently thereof by means of the second transmission device. 
         [0008]    In particular, the first effecting device and the second effecting device have no component parts in common. The second effecting device can be designed as a fully independent structural part that can be separated from the first effecting device without destruction. The first effecting device is in particular designed to be able to perform its intended function and action even in the absence of the cutting device. 
         [0009]    The first effecting device comprises in particular several jaw parts, of which at least one is pivotable, for grasping or squeezing tissue. The second effecting device comprises in particular a scalpel or a knife with a cutting edge for cutting through tissue, in particular for cutting through tissue that has been grasped, squeezed and obliterated beforehand by means of the first effecting device. 
         [0010]    The outer shaft is curved in particular, in order to permit or simplify use in single-port surgery, in which several medical instruments are introduced through a single opening or a single access point into a hollow space. Curvability of the outer shaft signifies a reversible, destruction-free, elastic and/or plastic deformability of the outer shaft. Alternatively or in addition to a curvature or a curvability of the outer shaft, it is possible to provide a pivot joint, which is substantially perpendicular to the longitudinal axis of the outer shaft. In the case of a curvature of the outer shaft, the pivot axis of the pivot joint is in particular perpendicular to the local longitudinal axis of the outer shaft near the pivot joint. 
         [0011]    Particularly for single-port surgery, a (for example substantially helically) curved outer shaft with a pivot joint near its distal end can considerably improve the application possibilities of the outer shaft. 
         [0012]    The first transmission device and the second transmission device are each completely flexible or have one or more flexible sections. In order to transmit longitudinal forces and/or torques, the transmission devices are each rigid in the longitudinal direction and/or torsionally rigid. The flexibility of the first transmission device and of the second transmission device is based in each case on an elastic or reversible plastic deformability, in particular on bending elasticity, and/or on one or more pivot joints in the corresponding transmission device. 
         [0013]    A medical instrument with the features described here can permit particularly versatile or universal application. On account of the curvature or the curvability of the outer shaft and/or by means of the pivot joint, the tool with the two effecting devices for two different functions can be optimally positioned with respect to the tissue in a great many situations, the tissue being grasped, squeezed, obliterated and cut through, for example. Medical personnel no longer have to decide, or have to decide much less often, as to which medical instrument to choose from a large number of alternative instruments (with different functions and a different arrangement of a tool with a effecting device) and then use. A greater number of different steps can be performed with a single medical instrument, with the result that, during a micro-invasive surgical intervention, the medical instrument being used has to be exchanged much less often. It is possible in this way to reduce the time period required for a specific micro-invasive surgical intervention, to lessen the burden placed on the patient and on the medical personnel, and to reduce costs. Cost reductions are achieved by the fact that the versatility of the individual medical instrument means that a smaller number of instruments have to be kept in stock. 
         [0014]    In a medical instrument as described here, the tool and the outer shaft have, in particular, coupling devices by which the tool is mechanically connected in a releasable manner to the distal end of the outer shaft. 
         [0015]    The coupling devices are in particular designed to form a mechanical connection that can be released without destruction and that is reversible. The coupling devices comprise, in particular, bayonet coupling devices, screw threads or other devices for the form-fit or force-fit releasable mechanical connection. 
         [0016]    The releasability of the connection between tool and outer shaft can make it easier to clean the medical instrument after use and to prepare it for a further use. Moreover, the releasable mechanical connection between tool and outer shaft can make it easier to exchange the tool or the outer shaft in the event of a defect. Moreover, several different tools with different features and/or several different outer shafts with different features can be kept in stock and can be used in the manner of a modular system. 
         [0017]    In a medical instrument as described here, outer shaft and manipulation device have, in particular, coupling devices for releasable mechanical connection of the proximal end of the outer shaft to the manipulation device. 
         [0018]    The coupling devices are in particular designed for destruction-free and reversibly releasable connection of the outer shaft and manipulation device. 
         [0019]    In a medical instrument as described here, the first transmission device and the second transmission device are in particular arranged coaxially in the outer shaft. 
         [0020]    A coaxial arrangement of the first transmission device and of the second transmission device in the outer shaft is obtained when the first transmission device and the second transmission device are arranged coaxially to each other in the outer shaft. Moreover, the first transmission device and the second transmission device can be arranged coaxially with respect to the outer shaft. A coaxial arrangement can in particular facilitate a rotatability of the outer shaft relative to the manipulation device and/or a rotatability of the tool relative to the outer shaft and/or a rotatability of a pivot joint relative to a proximal section of the outer shaft. 
         [0021]    In a medical instrument as described here, the first transmission device and the second transmission device are, in particular, arranged alongside each other in the outer shaft. 
         [0022]    An arrangement of the first transmission device and of the second transmission device alongside each other may be advantageous in respect of the required installation space, particularly in respect of the necessary cross sections. In particular, a smaller cross-sectional surface of the outer shaft can be achieved than in the case of a coaxial arrangement. 
         [0023]    A medical instrument with a pivot joint, as described here, also comprises, in particular, a third transmission device, of which the distal end is coupled to the pivot joint, in order to control the pivot joint. 
         [0024]    The third transmission device is coupled directly or indirectly to the pivot joint, in particular by means of a linking rod or by means of slide surfaces, in such a way that a longitudinal translation of the third transmission device parallel to the outer shaft is associated with a pivoting of the tool about the pivot axis of the pivot joint. The third transmission device is designed to be elastic, particularly in the case of a curved or curvable outer shaft. 
         [0025]    A medical instrument as described here also comprises, in particular, a rotation joint located proximally of the pivot joint, for rotating the pivot joint relative to the proximal end of the outer shaft, wherein the third transmission device is further designed to control the rotation joint. 
         [0026]    The rotation joint is in particular arranged immediately proximally of the pivot joint, the distance between the pivot axis of the pivot joint and the rotation joint being only a few (at most 5 or 10) external diameters of the outer shaft. The rotation axis of the rotation joint is in particular parallel to the longitudinal axis of the outer shaft, and, in the case of a curvature or a curvability of the outer shaft, is parallel to the local longitudinal axis of the outer shaft near the rotation joint. A rotation of the pivot joint about the rotation axis of the rotation joint is also associated with a rotation of the pivot axis of the pivot joint. 
         [0027]    In a medical instrument as described here, the third transmission device is arranged, in particular, coaxially in the outer shaft. 
         [0028]    In particular, the third transmission device has the form of a tube or a hose and is arranged in a substantially annular space between the outer shaft, on the one hand, and the first transmission device and the second transmission device, on the other hand. 
         [0029]    In a medical instrument as described here, the first effecting device is designed in particular as a bipolar electrosurgical instrument with mutually electrically insulated electrodes, wherein one of the mutually electrically insulated electrodes is connected electrically conductively to the outer shaft and to the first transmission device. 
         [0030]    The mutually electrically insulated electrodes are in particular each formed by a respective jaw part of the first effecting device or are provided on a respective jaw part of the first effecting device. The mutually electrically insulated electrodes can be connected via the outer shaft or via the first transmission device to an electrical high-frequency output source and to the poles thereof. 
         [0031]    In particular, in a medical instrument as described here, the second transmission device is mechanically connected to the tool in a releasable manner by means of a bayonet coupling, and a locking device is provided on the second transmission device for the purpose of coupling the second transmission device to the first transmission device or to the outer shaft or to a third transmission device, in such a way that the second transmission device is not rotatable relative to the first transmission device or relative to the outer shaft or relative to the third transmission device. 
         [0032]    The second transmission device is connected to the second effecting device, in particular directly, by means of the bayonet coupling. The locking device serves to directly lock the bayonet coupling by suppressing the rotation of the second transmission device relative to the tool, in particular relative to the second effecting device, which rotation is necessary for the release of the bayonet coupling. The locking device can be arranged near the bayonet coupling and thus near the distal end of the second transmission device. With sufficient torsional rigidity of the second transmission device and of the outer shaft, the first transmission device or the third transmission device, it is alternatively possible to provide the locking device at any other desired location on the second transmission device, for example at the proximal end thereof. 
         [0033]    The described combination of a bayonet coupling with a locking device permits releasability of the mechanical connection between tool and second transmission device in a way that requires little installation space. Since the locking device can be arranged at a distance from the bayonet coupling, for example at the proximal end of the medical instrument, installation space can be saved in particular at the distal end of the medical instrument. 
         [0034]    A medical instrument as described here also comprises, in particular, a rotation joint arranged proximally of the tool, for rotating the tool relative to the outer shaft. 
         [0035]    The rotation joint arranged proximally of the tool can be connected non-releasably to the tool. In the case of a pivot joint, the rotation joint is provided distally of the pivot joint, or between tool and pivot joint. The rotation joint arranged proximally of the tool can permit an optimal alignment or orientation of the tool. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]    Embodiments are explained in more detail below with reference to the attached figures, in which: 
           [0037]      FIG. 1  shows a schematic view of a medical instrument; 
           [0038]      FIG. 2  shows a further schematic view of the medical instrument from  FIG. 1 ; 
           [0039]      FIG. 3  shows a further schematic view of the medical instrument from  FIGS. 1 and 2 ; 
           [0040]      FIG. 4  shows a further schematic view of the medical instrument from  FIGS. 1 to 3 ; 
           [0041]      FIG. 5  shows a schematic axonometric view of a grasping device for a medical instrument; 
           [0042]      FIG. 6  shows a schematic axonometric view of a cutting device; 
           [0043]      FIG. 7  shows a further schematic axonometric view of the devices from  FIGS. 5 and 6 ; 
           [0044]      FIG. 8  shows a schematic sectional view of a transmission device and of an inner shaft; 
           [0045]      FIG. 9  shows a schematic sectional view of a further transmission device and of an inner shaft; 
           [0046]      FIG. 10  shows a further schematic sectional view of the transmission device and of the inner shaft from  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0047]      FIG. 1  shows a schematic view of a medical instrument  10  with a proximal end  11  and a distal end  12 . The medical instrument  10  has, at the proximal end  11 , a manipulation device  18  with a plurality of movable grip parts and other actuating devices. A curved outer shaft  20  extends from the manipulation device  18  at the proximal end  11  to a grasping device  30  and a cutting device  50  at the distal end  12  of the medical instrument  10 . 
         [0048]    Whereas in  FIG. 1  the manipulation device  18  is indicated only by its contours and the grasping device  30  and the cutting device  50  are shown in a side view, a substantially tubular section  23  of the outer shaft  20  is shown in longitudinal section. The tubular section  23  contains, in a coaxial arrangement, a transmission rod  40 , an internal inner shaft  60  and an external inner shaft  70 . The internal inner shaft  60  and the external inner shaft  70  are each tubular or hose-shaped. The transmission rod  40 , the internal inner shaft  60  and the external inner shaft  70  are each flexurally elastic, stiff in respect of longitudinal forces and torsionally rigid. The internal inner shaft  60  is arranged in an annular space between the transmission rod  40  and the external inner shaft  70 . The external inner shaft  70  is arranged in an annular space between the internal inner shaft  60  and the tubular section  23  of the outer shaft  20 . 
         [0049]    Arranged immediately proximally of the grasping device  30 , a pivot joint  24  is provided which is connected mechanically to the tubular section  23  of the outer shaft  20 , either releasably or non-releasably, and in particular forms a component part of the outer shaft  20 . The pivot joint  24  permits a pivoting of the grasping device  30  and of the cutting device  50  about a pivot axis  25  perpendicular to the plane of the drawing of  FIG. 1 . The pivot joint  24  and the pivot axis  25  are rotatable, relative to the curved, tubular section  23  of the outer shaft  20 , about a rotation axis  28  in the plane of the drawing in  FIG. 1 . The rotation axis  28  is defined by a rotation joint not shown in  FIG. 1 . 
         [0050]    The proximal end  31  of the grasping device  30  is mechanically connected to the pivot joint  24  in a releasable manner. A stationary jaw part  32  and a pivotable jaw part  34 , which is pivotable about a pivot axis  35  perpendicular to the plane of the drawing of  FIG. 1 , form the distal end of the grasping device  30 . The solid line shows the pivotable jaw part  34  in an open position, spaced apart from the stationary jaw part  32 , and the broken line shows it in a closed position, bearing on the stationary jaw part  32 . Together with the pivot axis  35  and the cutting device  50 , the grasping device  30  is rotatable about the longitudinal axis  38  of the grasping device  30  relative to the pivot joint  24 . 
         [0051]      FIG. 2  shows a further schematic view of the medical instrument  10  from  FIG. 1 . The plane of the drawing of  FIG. 2  is perpendicular to the plane of the drawing of  FIG. 1  and parallel to the pivot axis  25  of the pivot joint  24  and to the rotation axis  28  about which the pivot joint  24  is rotatable relative to the tubular section  23  of the outer shaft  20 . In contrast to  FIG. 1 , the outer shaft  20  in  FIG. 2  is shown exclusively in an external and side view. 
         [0052]      FIG. 3  shows a further schematic view of the medical instrument from  FIGS. 1 and 2 . The plane of the drawing of  FIG. 3  is perpendicular to the plane of the drawing of  FIG. 1 , perpendicular to the plane of the drawing of  FIG. 2 , perpendicular to the longitudinal axis  38  of the grasping device  30  (cf.  FIG. 2 ), perpendicular to the rotation axis  28  about which the pivot joint  24  is rotatable relative to the tubular section  23  of the outer shaft  20 , parallel to the pivot axis  25  of the pivot joint  24  and parallel to the pivot axis  35  of the pivotable jaw part  34 . 
         [0053]    Comparing  FIGS. 1 to 3 , it will be seen that the outer shaft  20  has a spatial curvature, i.e. not a planar curvature, and in particular has a configuration similar to a screw or a helix. 
         [0054]      FIG. 4  shows a further schematic view of the medical instrument from  FIGS. 1 to 3 . The plane of the drawing of  FIG. 4  corresponds to the plane of the drawing of  FIG. 1 . The view in  FIG. 4  differs from the views in  FIGS. 1 to 3  in that component parts into which the medical instrument  10  can be dismantled without destruction, i.e. reversibly, by medical personnel without using tools, are shown separately. The flexurally elastic transmission rod  40 , the flexurally elastic internal inner shaft  60  and the flexurally elastic external inner shaft  70  are each shown in rectilinear form. Dot-and-dash lines indicate how the component parts of the medical instrument are to be assembled. 
         [0055]    The flexurally elastic, torsionally rigid transmission rod  40 , which is stiff with respect to longitudinal forces, is mechanically connected to the grasping device  30 . As is explained in detail below with reference to  FIG. 5 , the distal end of the transmission rod  40  is mechanically coupled and electrically conductively connected to the pivotable jaw part  34  and is electrically insulated from the stationary jaw part  32  and from bayonet claws or catches  37  at the proximal end  31  of the grasping device  30 . As is likewise explained below with reference to  FIGS. 5 to 7 , the grasping device  50  can be inserted from the proximal direction into a channel in the transmission device  40  and into the grasping device  30 . 
         [0056]    The tubular or hose-shaped internal inner shaft  60  has a lumen whose cross section is adapted to the cross section of the transmission rod  40 , such that the transmission rod  40  is guided with minimal play and minimal friction in the internal inner shaft  60 . At the distal end  62 , the internal inner shaft  60  has an L-shaped slit with an axial section  63  and a circumferential section  64 . The L-shaped slit  63 ,  64 , a projection  56  on the cutting device  50 , and the function thereof, are likewise explained below with reference to  FIGS. 5 to 7 . 
         [0057]    The external inner shaft  70  is mechanically connected to the pivot joint  24 . In particular, the distal end of the external inner shaft  70  is coupled to the pivot joint  24  in such a way that an axial translation movement of the external inner shaft  70  is associated with a pivoting movement of the distal part of the pivot joint  24  about the pivot axis  25  relative to the proximal part of the pivot joint  24 . At the distal end of the pivot joint  24 , L-shaped grooves  27  are formed which correspond to the catches  37  at the proximal end  31  of the grasping device  30 , for releasable mechanical connection of the tool  30  to the pivot joint  24 . The proximal end of the pivot joint  24  can be mechanically connected in a releasable manner to the distal end of the tubular section  23  of the outer shaft  20  by means of devices not shown in  FIG. 4 . In particular, bayonet coupling devices are provided at the proximal end of the pivot joint  24  and at the distal end of the tubular section  23  of the outer shaft  20 . 
         [0058]    The external inner shaft  70  is substantially tubular or hose-shaped. The cross section of the lumen of the external inner shaft  70  is adapted to the cross section of the internal inner shaft  60  in such a way that the internal inner shaft  60  is guided and movable in the external inner shaft  70  with minimal play and minimal friction. The cross section of the lumen of the tubular section  23  of the outer shaft  20  is adapted to the cross section of the external inner shaft  70  in such a way that the external inner shaft  70  is guided and movable in the tubular section  23  of the outer shaft  20  with minimal play and minimal friction. 
         [0059]    The proximal end  21  of the outer shaft  20 , or of the tubular section  23  of the outer shaft  20 , can be locked with a form fit in a corresponding recess in the manipulation device  18  by means of a locking device not shown in  FIGS. 1 to 4 . In the arrangement shown in  FIG. 1 , the proximal end  41  of the transmission rod  40 , the proximal end  61  of the internal inner shaft  60  and the proximal end  71  of the external inner shaft  70  are mechanically coupled to actuating devices on the manipulation device  18  by way of devices not shown in  FIGS. 1 to 4 . 
         [0060]    In particular, the proximal end  41  of the transmission rod  40  is coupled to a pivotable grip part of the manipulation device  18  in such a way that the transmission rod  40  is displaceable in its longitudinal direction, in order to pivot the pivotable jaw part  34  between the open position, shown by solid lines in  FIGS. 1 ,  3  and  4 , and the closed position, shown by broken lines in  FIGS. 1 ,  3  and  4 . Moreover, the transmission rod  40  is coupled to a further actuating device, for example a rotary wheel, in such a way that the transmission rod  40  is rotatable about its longitudinal axis, in order to rotate the grasping device  30  about its longitudinal axis  38  together with the cutting device  50 . 
         [0061]    Moreover, the proximal end  61  of the internal inner shaft  60  is coupled to a further actuating device of the manipulation device  18  in such a way that the internal inner shaft  60  can be displaced axially, i.e. in its longitudinal direction, in order to move the cutting device  50  parallel to the longitudinal axis  38  of the grasping device  30 . Moreover, the proximal end  71  of the external inner shaft  70  is mechanically coupled to a further actuating device of the manipulation device  18  in such a way that the external inner shaft  70  can be displaced axially, i.e. in the longitudinal direction, in order to pivot the grasping device  30  and the cutting device  50 , together with the distal part of the pivot joint  24 , about the pivot axis  25 . Moreover, the proximal end  71  of the external inner shaft  70  is mechanically coupled to a further actuating device of the manipulation device  18  in such a way that the external inner shaft can be rotated about its longitudinal axis, in order to rotate the pivot joint  24 , together with the pivot axis  25 , about the rotation axis  28  relative to the distal end of the tubular section  23  of the outer shaft  20 . 
         [0062]      FIG. 5  shows a schematic axonometric view of the grasping device  30 , which is provided and designed to form a medical instrument, as is explained above with reference to  FIGS. 1 to 4 . The grasping device  30  has a proximal end  31  and two jaw parts  32 ,  34 , which form the distal end of the grasping device  30 . Near the proximal end  31 , the grasping device  30  has two symmetrically arranged bayonet claws or catches  37 , of which one is arranged on a side facing away from the viewer and is therefore largely concealed. The grasping device  30  shown in  FIG. 5  differs from what has been explained above with reference to  FIGS. 1 to 4  in terms of a slightly different arrangement of the catches  37 . Otherwise, the grasping device  30  shown in  FIG. 5  corresponds substantially to the grasping device of the medical instrument explained above with reference to  FIGS. 1 to 4 . 
         [0063]    The grasping device  30  is mechanically connected to the transmission rod  40 . The transmission rod  40  is movable, within a predetermined range, relative to the grasping device  30 , in particular relative to the proximal end  31  and to the stationary jaw part  32 , in the axial direction, i.e. parallel to the longitudinal axis of the transmission rod  40  and to the longitudinal axis  38  of the grasping device  30  (cf.  FIGS. 1 and 2 ). The distal end of the transmission rod  40  is arranged inside the grasping device  30  and is therefore not visible in  FIG. 5 , and it is coupled to the pivotable jaw part  34  in such a way that an axial movement of the transmission rod  40  is associated with a pivoting movement of the pivotable jaw part  34 . 
         [0064]    A groove  45 , which in particular has a narrow and deep rectangular cross section, is provided in the transmission rod  40 . At its distal end, not visible in  FIG. 5 , the groove  45  in the transmission rod  40  is continued by a channel of corresponding cross section which extends between the jaw parts  32 ,  34  to almost the distal ends of the latter. 
         [0065]    Parts of the grasping device  30 , in particular the catches  37  and the transmission rod  40 , are made of stainless steel or another metal. The catches  37  and the transmission rod  40  are electrically insulated from each other. The jaw parts  32 ,  34  have metallic and therefore electrically conductive grasping surfaces, which are electrically insulated from each other when they are not bearing on each other as shown in  FIG. 5 . The catches  37  and the transmission rod  40  are each electrically conductively connected to the grasping surface of a jaw part  32 ,  34 . In particular, the catches  37  are electrically conductively connected to the grasping surface of the stationary jaw part  32 , and the transmission rod  40  is electrically conductively connected to the grasping surface of the pivotable jaw part  34 . 
         [0066]      FIG. 6  shows a schematic axonometric view of the cutting device  50  with a proximal end  51  and a distal end  52 . At the distal end  52 , the cutting device  50  has a cutting edge  53 . At the proximal end, the cutting device  50  has a projection  56 . Between the proximal end  51  and the distal end  52 , the cutting device comprises a rod-shaped area  54 , which has substantially the configuration of a strip-shaped plate or of a rod with a rectangular cross section. 
         [0067]    Between the projection  56  at the proximal end  51  and the cutting edge  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  (cf.  FIG. 5 ), such that the cutting device  50  is received completely, except for the projection  56 , by the groove  45  in the transmission device  40  and is guided in the latter with minimal play and minimal friction and can be moved in the longitudinal direction of the transmission rod  40  and of the cutting device  50 . The projection  56  is provided to protrude from the groove  45  in the transmission rod  40 . 
         [0068]      FIG. 7  shows a further axonometric view of the grasping device from  FIG. 5  and of the cutting device  50  from  FIG. 6 . In the view in  FIG. 7 , the cutting device  50  is arranged in the groove  45  in the transmission rod  40  (cf.  FIG. 5 ). The distal end  52  of the cutting device  50  (cf.  FIG. 6 ) is arranged here in the grasping device and in particular between the jaw parts  32 ,  34 . The projection  56  protrudes from the groove  45 . 
         [0069]      FIG. 7  also shows the internal inner shaft  60 , which has substantially a tubular shape or the shape of a jacket of a circular cylinder. At its distal end  62 , the internal inner shaft  60  has an L-shaped slit with an axial or axially extending section  63  and a circumferential or circumferentially extending section  64 . The width of the axial section  63  of the L-shaped slit, measured in the circumferential direction, and the width of the circumferential section  64  of the L-shaped slit, measured in the axial direction, are adapted to the dimensions of the projection  56  on the cutting device  50 . 
         [0070]    After the transmission rod  40  has been inserted into the internal inner shaft  60 , the projection  56  can be guided by a relative movement in the axial direction through the axial section  63  and into the circumferential section  64 . When the projection  56  on the cutting device  50  is located in the circumferential section  64  of the L-shaped slit at the distal end  62  of the internal inner shaft  60 , the internal inner shaft  60  can be rotated relative to the grasping device  30 , the transmission rod  40  and the cutting device  50 , in a first direction  91 , as far as the configuration shown in  FIG. 7 . 
         [0071]    In the relative positioning of cutting device  50  and internal inner shaft  60  shown in  FIG. 7 , the cutting device  50  and the internal inner shaft  60  are rigidly coupled to each other in terms of axial movements (except for play). An axial movement of the internal inner shaft  60  is therefore associated with a corresponding axial movement of the cutting device  50 . Thus, by means of the internal inner shaft  60 , a movement of the cutting edge  53  at the distal end  52  of the cutting device  50  (cf.  FIG. 6 ) can be effected in said channel (not shown in the figures) between the jaw parts  32 ,  34 , such that, for example, tissue that is grasped by the jaw parts  32 ,  34  can be separated after electro-cauterization. 
         [0072]    The internal inner shaft  60  has an insulating jacket  69 , which has a distal edge lying near the L-shaped slit  63 ,  64 , and which can extend to near the proximal end of the internal inner shaft  60 . 
         [0073]      FIG. 8  shows a schematic sectional view of an example of how the mechanical coupling, explained above with reference to  FIG. 7 , between the projection  56  at the proximal end of the cutting device  50  and the L-shaped slit  63 ,  64  at the distal end  62  of the internal inner shaft  60  is locked. The sectional plane in  FIG. 8  is perpendicular to the plane of the drawing of  FIG. 1 , perpendicular to the plane of the drawing of  FIG. 2 , parallel to the plane of the drawing of  FIG. 3 , and perpendicular to the plane of the drawing of  FIG. 4 . The sectional plane in  FIG. 8  lies immediately proximally of the distal end  62  of the internal inner shaft  60  in the area of the axial section  63  of the L-shaped slit (cf.  FIGS. 4 and 7 ). 
         [0074]    The internal inner shaft  60  has an axial, or axially extending, locking slit  67  which lies substantially opposite the L-shaped slit  63 ,  64 . Thus, in relation to the views shown in  FIGS. 5 and 7 , the axial locking slit  67  lies on a side facing away from the viewer. The transmission rod  40  has a projection  47 , which corresponds to the axial locking slit  67  on the internal inner shaft  60  and which, for example, is in the form of a lug, an axially extending web or a pin. 
         [0075]    The angle position of the projection  47  relative to the groove  45  (cf.  FIGS. 4 and 7 ) in the transmission rod  40  and the angle position of the axial locking slit  67  relative to the L-shaped slit  63 ,  64  in the internal inner shaft  60  are chosen such that the projection  56  on the cutting device  50 , arranged in the groove  45  in the transmission rod  40 , is held in the circumferential section  64  of the L-shaped slit at the distal end  62  of the internal inner shaft  60  when the projection  47  on the transmission rod  40  engages in the axial locking slit  67  on the internal inner shaft  60 , as is shown in  FIG. 8 . The projection  47  is arranged so far distally of the proximal end of the groove  45  in the transmission rod  40  (cf.  FIGS. 5 and 7 ) that, first of all, the cutting device  50  can be inserted into the groove  45  in the transmission rod  40  and can be coupled to the distal end  62  of the internal inner shaft  60  in the manner described above with reference to  FIG. 7 . Thereafter, the internal inner shaft  60  is moved distally together with the cutting device  50 . It is only with this movement of the internal inner shaft  60  in the distal direction that the projection  47  on the transmission rod  40  engages in the axial locking slit  67  on the internal inner shaft  60 , as is shown in  FIG. 8 , in order to lock the mechanical connection between the cutting device  50  and the internal inner shaft  60 . 
         [0076]      FIG. 9  shows a schematic sectional view of another example of how the internal inner shaft  60  is locked relative to the transmission rod  40 . The sectional plane in  FIG. 9  is perpendicular to the plane of the drawing of  FIG. 1 , perpendicular to the plane of the drawing of  FIG. 2 , parallel to the plane of the drawing of  FIG. 3 , perpendicular to the plane of the drawing of  FIG. 4 , and parallel to the sectional plane in  FIG. 8 . 
         [0077]    The transmission rod  40  has two flat surfaces  46  lying opposite each other. The internal inner shaft  60  has two openings lying opposite each other, in which a bolt  66  is in each case mounted so as to be radially movable. The bolts  66  are in particular movable between radially inward locking positions and the radially outward unlocking positions shown in  FIG. 9 . The bolts  66  can be held in the recesses in the internal inner shaft  60  by an O-ring made of an elastic material or by other devices not shown in  FIG. 9  and/or can be pressed radially inward into the locking positions. 
         [0078]      FIG. 10  shows a further schematic sectional view of the example from  FIG. 9 . The sectional plane in  FIG. 10  corresponds to the sectional plane in  FIG. 9 . The view in  FIG. 10  differs from the view in  FIG. 9  in that the internal inner shaft  60  is rotated relative to the transmission rod  40  to the extent that the bolts  66  can assume their radially inward locking positions and in so doing can bear on the flat surfaces  46  on the transmission rod  40 . 
         [0079]    In the view in  FIG. 10 , the transmission rod  40  and the internal inner shaft  60  are arranged in the external inner shaft  70 . Here, radially outer surfaces of the bolts  66  bear on the inner surface of the external inner shaft  70 . In this way, the bolts  66  are held with a form fit in their locking position shown in  FIG. 10 . Thus, when the transmission rod  40  and the internal inner shaft  60  are arranged in the external inner shaft  70  as shown in  FIG. 10 , the transmission rod  40  is locked in terms of rotation about its longitudinal axis relative to the internal inner shaft  60 . 
         [0080]    The angle positions of the flat surfaces  46  relative to the groove  45  in the transmission rod  40  (cf.  FIGS. 5 and 7 ) and the angle positions of the openings in the internal inner shaft  60 , receiving the bolts  66 , relative to the L-shaped slit  63 ,  64  at the distal end  62  of the internal inner shaft  60  are chosen such that, in the locked configuration shown in  FIG. 10 , the projection  56  of the cutting device  50  is held in the groove  45  in the form-fit connection shown in  FIG. 7  with the circumferential section  64  of the L-shaped slit at the distal end  62  of the internal inner shaft  60 . Thus, in the configuration shown in  FIG. 10 , the mechanical connection between cutting device  50  and inner shaft  60  is locked. 
         [0081]    The locking between transmission rod  40  and internal inner shaft  60 , as has been explained with reference to  FIGS. 9 and 10 , can be arranged near the distal end of the internal inner shaft  60  or, if the transmission rod  40  and the internal inner shaft  60  have a sufficiently torsionally rigid design, can be arranged at any other desired location as far as the proximal ends of the transmission rod  40  and of the internal inner shaft  60 . 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 Reference signs 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 10 
                 medical instrument 
               
               
                 11 
                 proximal end of the medical instrument 10 
               
               
                 12 
                 distal end of the medical instrument 10 
               
               
                 18 
                 manipulation device at the proximal end 11 of the medical 
               
               
                   
                 instrument 10 
               
               
                 20 
                 outer shaft of the medical instrument 10 
               
               
                 21 
                 proximal end of the outer shaft 20 
               
               
                 22 
                 distal end of the outer shaft 20 
               
               
                 23 
                 tubular section of the outer shaft 20 
               
               
                 24 
                 pivot joint at the distal end 22 of the outer shaft 20 
               
               
                 25 
                 pivot axis of the pivot joint 24 
               
               
                 27 
                 L-shaped groove at the distal end 22 of the outer shaft 20 
               
               
                 28 
                 rotation axis of the pivot joint 24 
               
               
                 30 
                 grasping device at the distal end 12 of the medical instrument 
               
               
                   
                 10 
               
               
                 31 
                 proximal end of the grasping device 30 
               
               
                 32 
                 stationary jaw part of the grasping device 30 
               
               
                 34 
                 pivotable jaw part of the grasping device 30 
               
               
                 35 
                 pivot axis of the pivotable jaw part 34 
               
               
                 37 
                 catch at the proximal end 31 of the grasping device 30 
               
               
                 38 
                 longitudinal axis of the grasping device 30 
               
               
                 40 
                 transmission rod of the medical instrument 10 
               
               
                 41 
                 proximal end of the transmission rod 40 
               
               
                 45 
                 groove in the transmission rod 40 
               
               
                 46 
                 flattened surface on the transmission rod 40 
               
               
                 47 
                 projection 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 
                 cutting edge on the cutting device 50 
               
               
                 54 
                 rod-shaped area of the cutting device 50 
               
               
                 56 
                 projection at the proximal end 51 of the cutting device 50 
               
               
                 60 
                 internal inner shaft of the medical instrument 10 
               
               
                 61 
                 proximal end of the internal inner shaft 60 
               
               
                 62 
                 distal end of the internal inner shaft 60 
               
               
                 63 
                 axial section of an L-shaped slit at the distal end 62 
               
               
                 64 
                 circumferential section of an L-shaped slit at the distal end 62 
               
               
                 66 
                 bolt on the internal inner shaft 60 
               
               
                 67 
                 axial locking slit on the internal inner shaft 60 
               
               
                 69 
                 insulating jacket on the internal inner shaft 60 
               
               
                 70 
                 external inner shaft of the medical instrument 10 
               
               
                 71 
                 proximal end of the external inner shaft 70