Abstract:
The invention relates to a tubular medical instrument having a hollow shaft, a handle positioned on the proximal end of the shaft and equipped with at least two gripping members, and at least one push-pull rod that is positioned in the hollow shaft and has on its distal end a tool consisting of at least two jaw members, wherein for opening and closing at least one jaw member of the tool, the push-pull rod can be coupled with at least one rotatable gripping member of the handle and wherein the push-pull rod and the handle can be detachably connected to one another by a coupling mechanism that is configured as at least one clamping device comprising at least one clamping claw characterized in that the at least one clamping claw can rotate in a guide track mounted between a closed position and an open installation position. To create a coupling mechanism that is easy to handle, it is proposed according to the invention that the at least one clamping claw is mounted in a guide track so that it can rotate between a closed clamping position and an open installation position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application claims priority of German patent application No. 10 2006 038 515.2 filed on Aug. 17, 2006, the content of which is incorporated herein by reference.  
       FIELD OF THE INVENTION  
       [0002]     The invention relates to a tubular medical instrument having a hollow shaft, a handle positioned on the proximal end of the shaft and equipped with at least two gripping members, and at least one push-pull rod that is positioned in the hollow shaft and has on its distal end a tool consisting of at least two jaw members, wherein for opening and closing at least one jaw member of the tool, the push-pull rod can be coupled with at least one rotatable gripping member of the handle and wherein the push-pull rod and the handle can be detachably connected to one another by a coupling mechanism that is configured as a clamping device comprising at least one clamping claw.  
       BACKGROUND OF THE INVENTION  
       [0003]     Tubular medical instruments of this type are used, for instance, in the configuration as needle holder, in endoscopic surgery. Because of increasingly stringent hygienic demands, it is more and more often required that tubular instruments, particularly those comprising hollow spaces such as hollow shafts, should be configured so that they can be at least partially dismantled so that they can be submitted to thorough cleansing and sterilization, preferably by steam.  
         [0004]     A generic tubular medical instrument, configured as a medical forceps, is reported in DE 43 07 539 A1. This known tubular instrument can be broken down for cleansing and sterilization into three main groups: the push-pull rod, the hollow shaft, and the handle. The coupling mechanism for connecting the push-pull rod with the handle consists, in this construction, of a joint ball that is positioned on the proximal end of the push-pull rod, intended for insertion into a correspondingly formed coupling recess in the rotatable gripping member. This coupling has proved itself in the art, but it requires a very exact manufacturing of the push-pull rod.  
         [0005]     Consequently it is the object of the present invention to perfect a tubular medical instrument in such a way that the push-pull rod and the handle can be detachably connected to one another by means of a coupling mechanism that is essentially without play and is easily manufactured.  
       SUMMARY OF THE INVENTION  
       [0006]     This object is fulfilled by the invention in a manner characterized in that the at least one clamping claw mounted in a guide track can be rotated between a closed clamped position and an open installation position.  
         [0007]     Because of this configuration of the coupling mechanism as at least one clamping claw mounted in a guide track, an essentially play-free coupling is ensured between the push-pull rod and the handle and also tolerates variations in length of the push-pull rod.  
         [0008]     Because of the mounting of the clamping claw in the guide track, the rotation of the at least one clamping claw between the closed clamped position and the open installation position is facilitated, so that through the configuration of the guide for the clamping claw displacement, an exact, uniform motion of the at least one clamping claw into the respective coupling position is ensured. Advantageously, according to the invention, a control peg that engages in the guide track is positioned at each clamping claw mounted in a guide track.  
         [0009]     According to a preferred embodiment of the invention, the clamping device comprises two clamping claws.  
         [0010]     According to a practical embodiment of the invention, it is proposed that the clamping claws of the clamping device surround the proximal end of the push-pull rod at least partially in form-fitting connection, so that the proximal end of the push-pull rod is configured as a coupling element that can be surrounded at least partially by the clamping claws. The configuration of the clamping claws to grip the proximal end of the push-pull rod allows a space-saving structure for the coupling mechanism along with good force transmission because of the large transmitting surface.  
         [0011]     To configure the clamping connection between the clamping claws and the push-pull rod, the coupling element according to the invention is configured as a widening of the push-pull rod mounted downstream in the axial direction of the fixing point formed by the clamping claws. With this configuration it is also possible to secure the push-pull rod in the area of the fixing point either form-fitted or friction-engaged, but in any case clamped by means of the clamping claws.  
         [0012]     The coupling element, according to a practical embodiment of the invention, is configured by a constriction of the push-pull rod upstream of the proximal end in the axial direction.  
         [0013]     Alternatively, according to a second embodiment of the invention, it is proposed that at least one of the clamping claws should be configured as a spring element, so that the spring elasticity of this at least one clamping claw can be realized not only through the elasticity of the clamping claw material itself, but also through the spring-loading of this at least one clamping claw.  
         [0014]     Insertion of the proximal end of the push-pull rod into the clamping device can be facilitated according to the invention in that oblique contact elements are configured on the coupling element and/or on the clamping claws to prevent the tilting of components that run into one another.  
         [0015]     It is further proposed with the invention that the clamping claws are positioned so that they can rotate on a connecting member that can be coupled with at least one rotatable gripping member of the handle.  
         [0016]     It is finally proposed with the invention that the clamping device is pre-tensed by a spring element into the position that opens the clamping claws in order to allow for simple release of the coupling.  
         [0017]     Further characteristics and advantages of the invention can be seen from the appended illustrations, in which an embodiment of an inventive tubular medical instrument is depicted in merely schematic form. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  shows a schematic side view of an inventive tubular medical instrument.  
         [0019]      FIG. 2  shows a schematic side view of the instrument of  FIG. 1  when dismantled.  
         [0020]      FIG. 3  shows an enlarged partial schematic section of detail III from  FIG. 1 .  
         [0021]      FIG. 4   a  shows an enlarged partial schematic depiction according to  FIG. 3 , but presenting the clamping device in the open position.  
         [0022]      FIG. 4   b  shows a depiction according to  FIG. 4   a  but presenting the clamping device in the closed position. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]     The tubular medical instrument seen in  FIGS. 1 and 2 , configured as a needle holder, consists essentially of a handle  2  equipped with two gripping members  1 , a hollow shaft  3 , and a push-pull rod  4  that can be inserted into the hollow shaft  3  and has on its distal end a tool  5  consisting of two jaw members  5   a  and  5   b.    
         [0024]     The especially clearly depicted components in  FIG. 2 —the handle  2 , hollow shaft  3 , and push-pull rod  4 —can be coupled with one another by coupling and snap-on mechanisms in such a way that upon actuation of the gripping members  1  of the handle  2  the jaw members  5   a  and  5   b  of the tool  5  can be displaced between an open and a closed working position, so that the forces brought to bear by the user on the gripping members  1  of the handle  2  are transmitted by the push-pull rod  4  to the jaw members  5   a ,  5   b  of the tool  5 .  
         [0025]     As in the illustrated embodiment, the tool  5  comprises a rigid jaw member  5   a  and a jaw member  5   b  that can rotate with respect to the rigid jaw member  5   a . Of course it is also possible to configure both jaw members of the tool  5  as rotatable jaw members  5   b.    
         [0026]     As can be seen from  FIGS. 1 and 2 , in the illustrated embodiment both gripping members  1  of the handle  2  are configured as rotatable gripping members  1 , which are mounted so that they can rotate by contact points  6  on a housing  7  of the handle  2 . To convert the rotary motion of the gripping members  1  into a purely axial motion of the push-pull rod  4  and for force transmission of the pressure force exerted by the user through the handle  2  on the push-pull rod  4 , both gripping members  1  are connected by one articulated lever  8  each with a coupling rod  9 , which in turn is coupled directly or indirectly by a coupling mechanism with the push-pull rod  4 , so that the coupling of the push-pull rod  4  with the coupling rod  9  and thus with the handle  2  occurs in the coupling housing  10 .  
         [0027]     The coupling of the push-pull rod  4  and thus also of the jaw members  5   a  and  5   b  of the tool  5  with the gripping members  1  of the handle  2  is configured so that in pressing together the gripping members  1 , the push-pull rod is pulled by the articulated lever  8  and the coupling rod  9  in the axial direction toward the proximal end of the instrument. This axial sliding of the push-pull rod  4  to the proximal end of the instrument causes the jaw members  5   a ,  5   b  of the tool  5  to be moved into the closed working position. In this position, pressed together, the gripping members  1  can be fixed with respect to one another by a stopping device  11 , so that the user is not required to exert pressure continuously on the gripping members  1  of the handle  2 . By means of an unlocking button  12 , which separates the parts of the stopping device  11 , this fixing can be released again.  
         [0028]     Alternatively to the illustrated embodiment, it is also possible of course that the coupling of the push-pull rod  4  and thus also of the jaw members  5   a  and  5   b  of the handle  5  with the gripping members  1  of the handle  2  is configured in such a way that the push-pull rod  4  upon pressing together the gripping members  1  is pushed in the axial direction toward the distal end of the instrument.  
         [0029]     The gripping members  1  are advantageously pre-tensed  13  in the open position by a spring element which, as shown for instance in  FIG. 3 , is positioned in the coupling housing  10 . As soon as the unlocking button  12  is actuated, this spring element  13  pushed the push-pull rod  4  in the axial direction toward the distal end of the instrument, so that the gripping members  1  are pressed apart by the coupling rod  9  and the articulated lever  8 . This axial sliding of the push-pull rod  4  toward the distal end of the instrument causes the jaw members  5   a ,  5   b  of the tool  5  to be moved into the open working position.  
         [0030]     Alternatively to the illustrated embodiment of the handle  2  with two rotatable gripping members  1 , it is also possible of course to configure only one gripping member  1  that is rotatable, whereas the other gripping member in that case, for instance, is configured to be in a single unit and rigidly joined with the housing  7  of the handle  2 . In such an embodiment it is possible to couple the push-pull rod  4  directly with the rotatable gripping member  1 .  
         [0031]     The hollow shaft  3  that serves for insertion of the push-pull rod  4  can be coupled with the handle  2  by a coupling or snap-in mechanism that is positioned in the housing  7  of the handle  2 . In the illustrated embodiment of the tubular medical instrument, the hollow shaft  3  also comprises a rinsing connection  14 , which serves on the one hand to introduce rinsing liquid during an operation and on the other hand can have a rinsing hose connected to it to cleanse the hollow shaft  3 .  
         [0032]     On the distal side as well, the hollow shaft comprises a coupling or snap-on mechanism, to allow the coupling together of the hollow shaft  3  and the push-pull rod  4  that can be inserted into it.  
         [0033]     The structure of the coupling mechanism that can be positioned in the coupling housing  10  for dissoluble connection of the push-pull rod  4  with the handle  2  can be seen from  FIGS. 3 through 4   b.    
         [0034]     This coupling mechanism is configured as a clamping device  15 , which in the illustrated embodiment consists of two rotatably mounted clamping claws  16 , which surround the push-pull rod  4  in an at least partial form-fitting connection. For insertion into the clamping claws  16  of the clamping device  15 , a coupling element  17  is configured on the proximal end of the push-pull rod  4  and in the illustrated embodiment is configured in hammer-head shape as a constriction  18  mounted upstream of the proximal end in the axial direction.  
         [0035]     To facilitate insertion of the coupling element  17  into the clamping claws  16 , on the front surfaces of the coupling element  17  and those of the clamping claws  16  that run up against one another, oblique contact elements  19  are configured which serve to reduce the friction resistance of the components that contact one another.  
         [0036]     As can be seen from  FIGS. 3 through 4   b , the two clamping claws  16  are mounted with their proximal ends rotatable on the distal side of a connecting member  20 , which contacts the coupling rod  9  by means of a spring element  21 , where said coupling rod  9  in turn is coupled with the gripping members  1  by the articulated lever  8 . By actuating the gripping members  1  of the handle  2 , the clamping claws  16  of the clamping device  15  are thus actuated essentially without any free play, so that coupling of the push-pull rod  4  with the clamping claws  16  can occur exclusively in the installation position shown in  FIG. 4   a  with opened clamping claws  16 .  
         [0037]     The spring element  21  positioned with the handle  2  in the coupling area of the push-pull rod  4  is a safety device configured as a safety spring  21 , which prevents too great a force from being injected into the push-pull rod  4 . After the jaw members  5   a  and  5   b  of the tool  5  are closed, if the gripping members  1  of the handle  2  are pressed further together, this tractive force that is to be transmitted by the coupling rod  9  and the connecting member  20  onto the push-pull rod  4  is absorbed by the safety spring  21  and thus prevents damage to the push-pull rod  4  and/or to the jaw members  5   a  and  5   b  of the tool  5 . In securing the clamping connection caused by the clamping claws  16 , the safety device likewise prevents possible damage to the connecting member  20  and to the clamping claws  16 .  
         [0038]     On the distal end the clamping claws  16  are mounted, each by a control peg  22 , in a guide track  23 . Thanks to this peg-and-groove control, the clamping claws  16  with an axial pushing of the clamping device  15  are moved between the open installation position ( FIG. 4   a ) and the closed clamping position ( FIG. 4   b ). As can be seen from  FIGS. 3 and 4   b , because the guide tracks  23  run in an outward-bending curve only on their distal ends but otherwise run parallel to the instrument&#39;s longitudinal axis  24 , the clamping claws  16  can be opened only when the control pegs  22  guiding the clamping claws  16  enter into this curves of the guide tracks  23  on the distal end and thus rotate the clamping claws  16  into the opened installation position.  
         [0039]     As an alternative to the illustrated embodiment of the clamping claws  16 , it is also possible of course to configured them as spring elements or elastic clamping claws  16 , which are pre-tensed by internal stress or an external spring force into the closed position and thus surround the proximal end of the push-pull rod  4  in a form-locking connection.  
         [0040]     The composition of the illustrated tubular instrument and in particular of the coupling mechanism for connecting the hollow shaft  3  with the push-pull rod  4  is described hereafter with reference to  FIGS. 4   a  and  4   b.    
         [0041]     In the first two installation steps, the push-pull rod  4  and the hollow shaft  3  are coupled to one another and the hollow shaft  3  is connected with the handle  2 .  
         [0042]     Thereafter the gripping members  1  of the handle  2  are pressed as far apart as possible into the open position, in which they are supported by the spring element  13  positioned in the coupling housing  10 . Pressing apart the gripping members  1  of the handle  2  causes an axial motion of the coupling rod  9  by the articulated lever  8  in the direction of the distal end of the tubular instrument.  
         [0043]     Through the direct coupling of the coupling rod  9  with the connecting member  20 , on which the clamping claws  16  are mounted, the separation of the gripping members  1  of the handle  2  causes further pushing of the clamping claws  16  in the distal direction. Through the peg-and-channel control of the control pegs that engage in the guide tracks  23 , the clamping claws  16  in this axial motion are moved into the open installation position illustrated in  FIG. 4   a.    
         [0044]     In this position, the push-pull rod  4  can now be inserted into the opened clamping claws  16  with the proximal end, configured as a coupling element  17 , forward, a motion that is facilitated by the oblique contact elements  19  configured on both sides. In this open installation position, the gripping members  1  of the handle  2  assume an extra-open position, which said members can never assume in the practical operation of the instrument. This extra-open position of the gripping members  1  serves entirely or the installation of the push-pull rod  4 , so that accidental release of the push-pull rod  4  can be excluded in normal operation.  
         [0045]     To prevent accidental moving of the gripping members  1  of the handle  2  and thus also of the tool  5  into the extra-open installation position, it is possible, for instance in the area of the proximal end of the push-pull rod  4  and of the hollow shaft  3  mounted in the handle  2 , to position a limiting device that restricts the mobility of the push-pull rod  4  within the hollow shaft  3 . This limiting device, which is effective only in completely installed tubular instruments, allows an axial motion of the push-pull rod  4  only within the restricted distance that is necessary to rotate the jaw members  5   a ,  5   b  of the tool  5  between the open working position shown in  FIG. 1  and the closed working position. Because of the coupling of the axial displacement of the push-pull rod  4  with the angle of rotation of the gripping members  1  of the handle  2 , the limiting device that restricts the axial motion of the push-pull rod  4  thus causes at the same time a limitation of the angle of rotation of the gripping members  1  when they are fully installed.  
         [0046]     To conclude the installation, the push-pull rod  4  is pressed further in the axial direction all the way to the proximal end of the tubular instrument, a motion that can be supported by pressing together the gripping members  1  of the handle  2 . In this axial motion of the push-pull rod  4  in the direction of the proximal end of the tubular instrument, the clamping claws  16  are displaced along the guide tracks  23  proximally, so that said claws move into the closed position that surrounds the proximal end of the push-pull rod  4  in a form-fitting connection. In this position the clamping device  15  causes a coupling of the push-pull rod  4  with the handle  2  that is without free play and reliable.  
         [0047]     Dismantling, then, occurs in directly reverse order of the installation steps by releasing the snap-on connection between the hollow shaft  3  and the handle  2 , release of the connection of the push-pull rod  4  with the gripping members  1  of the handle  2 , and so on to the uncoupling of the hollow shaft  3  from the push-pull rod  4 . To release the connection of the push-pull rod  4  with the gripping members  1  of the handle  2 , the gripping members  1  are again pressed as far apart as possible until the clamping claws  16  again have assumed the installation position shown in  FIG. 4   a  and then the push-pull rod  4  can be uncoupled from the handle  2 .