Abstract:
A resectoscope includes an electrode arrangement having at least one electrode and being connected to a contact at a proximal end region of the electrode arrangement; a retaining body mounted on the resectoscope that is movable in the direction of movement of the electrode arrangement and includes an electrode mounting for accommodating the end region of the electrode arrangement; and a cable with a plug body for fixing to the retaining body while making contact with the contacts. The retaining body has a plug receptacle for fixing the plug body by an insertion movement aligned at right angles to the direction of movement of the electrode arrangement. In the position which is reached at the end of the insertion movement, the plug body can be turned into an end position where it is blocked by the plug receptacle against a movement in the opposite direction to the insertion movement.

Description:
BACKGROUND 
     The invention relates to a resectoscope. 
     Resectoscopes have a manually movable retaining body, by means of which an electrode, which, when HF is applied, can remove body tissue, can be moved in a longitudinal direction. A main area of application is prostate resection, in which the prostate tissue is cut in longitudinal movements away from the urethra with a cutting loop to which HF is applied. Apart from this application in urology, further applications of resectoscopes are known, primarily in gynecology for working in the uterus. 
     A resectoscope of the kind mentioned in the introduction is disclosed in U.S. Pat. No. 4,919,131 A. This publication is concerned mainly with the connection between the cable carrying the HF voltage from the outside and the electrode arrangement. A plug body, which connects a conductor in the cable to a conductor in the electrode arrangement, is presented. The plug body can be plugged into a plug receptacle in the main body for fixing and connecting purposes. 
     SUMMARY 
     With this known design, the plug body is pushed into the plug receptacle with only a linear sliding movement and held there by friction. This retention is uncertain, particularly when the cable is pulled during rough operation. This can then easily lead to a disengagement or loosening of the plug body and therefore to a deterioration or interruption of the contact. Connection problems are, however, very serious with high-frequency operation, as they can lead to burning of the contacts. This also jeopardizes reliable operation. 
     The object of the present invention consists in improving the connection reliability of a resectoscope of the kind mentioned in the introduction. 
     This object is achieved with the characteristics of the various embodiments. 
     According to an exemplary embodiment, the plug body is first inserted into the plug receptacle and, in the position reached at the end of the insertion movement, is then rotated into an end position in which it is blocked by the plug receptacle against a withdrawal movement. The plug body is thereby secured. A simple pull on the cable is no longer sufficient to loosen the plug body. Rather, a deliberate actuation which first requires a turning movement and then a pulling movement is necessary for this purpose. It is therefore ensured that a disengagement and loosening of the plug body can only take place intentionally and not unintentionally when using the resectoscope. This significantly increases the operational safety. 
     An exemplary embodiment describes a specific physical embodiment of the design in order to achieve the object according to the invention. According to this, the plug body is turned by means of the rotatable mounting of a cylinder formed on the plug body in a corresponding hollow cylinder in the retaining body. However, the plug body has a flattened periphery and, in a particular angular position, can be inserted from the outside into the region of the cylinder or removed therefrom through a slot. When the plug body is inserted through the slot into the region of the cylinder and then turned, it can no longer pass through the slot and is therefore secured by interlocking. 
     Preferably, according to an exemplary embodiment, the axis of the cylinder is aligned parallel to the direction of movement of the electrode arrangement. This enables a design which can be logically operated, in which the plug body can be inserted laterally through the slot at right angles to the direction of movement of the electrode arrangement. 
     Preferably, according to an exemplary embodiment, a latching device, which secures the plug body in the retaining body in its end position, is provided. This provides an additional safeguard against unintentional operation. 
     Preferably, according to an exemplary embodiment, the electrode mounting is formed in the plug body. This results in a direct connection of the electrode arrangement by means of the plug body, as in the design of the publication mentioned in the introduction. There are also advantages with regard to the contact quality and fault tolerance. 
     Advantageously, according to an exemplary embodiment, the electrode arrangement is designed in the form of a hole in the cylindrical part of the plug body. It could lie on the axis of rotation of the cylinder, which would also definitely have advantages, but it is advantageously displaced with respect to the axis of rotation of the cylinder towards the guide hole of the retaining body, by means of which the latter is movably guided in a longitudinal direction. As is known, there are always major problems with resectoscopes with the distance of the electrode mounting from the guide hole. Too great a distance must be compensated for by constructively difficult deviations of guide channels. The above described embodiment provides a remedy for this. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is shown by way of example and schematically in the drawings. In the drawings: 
         FIG. 1  shows a side view of a resectoscope according to the invention having a retaining body which can be moved in a longitudinal direction, 
         FIG. 2  shows an enlarged side view of  FIG. 1  in the region of the retaining body, 
         FIG. 3  shows a section according to Line  3 - 3  in  FIG. 2 , 
         FIGS. 4A and 4B  show a plug body according to exemplary embodiments, and 
         FIG. 5  shows a section according to Line  4 - 4  in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  shows a resectoscope  1  in side view. The resectoscope  1  corresponds substantially to the generally prevailing basic design. This includes a shaft tube  2 , over which a guide tube  3 , to the proximal end of which a guide plate  4  is fixed, projects in a proximal direction. A rod-shaped lens  5 , by means of which the operating region can be observed distally from the lens  5 , is inserted through said plate and the guide tube  3  into the shaft tube  2 . 
     In addition to the lens  5 , an electrode arrangement  6  is also arranged in the shaft tube  2 . The electrode arrangement is thin and elongated and is provided with an insulating sleeve over its length. In the distal end region, the electrode arrangement supports an electrode  7 , which can be designed in the form of a loop as is usual with resectoscopes. Further, a return electrode  10  is arranged in the distal end region, so that bipolar operation is possible with two electrodes  7  and  10 . 
     A retaining body  12  in the form of a slide which can be moved in a longitudinal direction is mounted on the guide tube  3 .  FIGS. 3 and 5  show that the retaining body  12  is mounted on the guide tube  3  by means of a guide hole  20 . 
       FIG. 1  shows that a spring  13  is arranged between the retaining body  12 , which is mounted so that it can be moved in a longitudinal direction, and the guide plate  4 , which is fixed with respect to the shaft tube  2 . Handle pieces  14  and  15 , which can be operated by the fingers of one hand and with which the retaining body  12  can be moved longitudinally against the force of the spring  13 , are fixed on the holding body  12  and on the guide plate  4 . 
       FIG. 1  shows that, with the electrode  7 , the electrode arrangement  6  runs from its distal end longitudinally through the shaft tube  2  and emerges therefrom proximally to run parallel to the guide tube  3  as far as the retaining body  12 .  FIG. 2  shows that a proximal end region  21  of the electrode arrangement  6  runs inside the retaining body  12  into an electrode mounting  22 , which is designed in the form of a hole which is aligned parallel to the guide tube  3 . 
     A slider  16  ( FIG. 5 ), which is provided with an actuating knob  23  and is mounted in the retaining body  12  so that it can be moved at right angles to the guide rod  3 , is provided with latching means (not shown), by means of which it can engage in a latching manner at the end region  21  of the electrode arrangement  6  to secure the latter in the electrode mounting  22  in the position shown in  FIG. 2 . By pressing the actuating knob  23 , the slider  16  can be moved so that the catch is released and the electrode arrangement can be withdrawn from the retaining body  12 . If the electrode arrangement is latched in the retaining body  12 , then it can be moved thereby in the longitudinal direction under fine control in order to be able to carry out the required tissue cuts with the electrode  7 . 
     In enlarged views of the retaining body  12 ,  FIGS. 2 and 5  show that a plug body  27 , which is attached to the end of a cable  26 , is releasably inserted in said retaining body. In  FIG. 2 , the plug body  27  is shown in its end position in the retaining body  12 . Here, the connection inside the plug body  27  can be seen dashed. Ring-shaped contact surfaces  28  and  29 , which are electrically connected to the electrodes  7  and  10  by means of internal conductors in the electrode arrangement  6 , are located on the end region  21  of the electrode arrangement  6 . In the position of the end region  21  shown, the ring-shaped contact surfaces  28  and  29  make contact with contact rings  30  and  31  which are arranged in the plug body  27  and are thereby connected to conductors  32  and  33  through the cable  26 . The cable  26  can be connected to the two poles of a bipolar current source in a manner which is not shown. 
       FIG. 3  shows a plug receptacle  34  in the retaining body  12  which is designed to accommodate the plug body  27 . The plug receptacle  34  forms a cylinder chamber  35  which is formed inside the retaining body  12  and is accessible from the outside through a slot  36 . 
     As  FIG. 4A  shows, the plug body  27  has a cylinder head  37  which is bounded by two cylinder surfaces  38 ,  39  and two parallel surfaces  40 ,  41 . The cylinder surfaces  38 ,  39  are formed so that they can run in a sliding manner inside the cylinder chamber  35 . The parallel surfaces  40 ,  41  are at a distance apart which is not greater than the height of the slot  36  and is less than the diameter of the cylinder chamber  35 . 
       FIG. 3  shows that, in its position shown dashed in  FIG. 3 , the plug body  27  can be moved with an inserting movement into the slot  36  in the direction of the arrow  47 . Here, it can be moved into the cylinder chamber  35  and can then be turned through 90° as shown by the arrow  48  into the position shown in which the cable  26  now hangs down. 
     In this position, the plug body  27  is retained in the retaining body  12  by interlocking, and can only be removed by turning back through 90° (in the opposite direction to arrow  48 ) and then withdrawing through the slot  36  (in the opposite direction to arrow  47 ). The plug body  27  can be secured against unintentional turning in the end position of the plug body  27  in the retaining body  12  shown in  FIG. 3 . On the one hand, the cable  26  which hangs down under gravity can be used for this purpose while the retaining body  12  is predominantly held so that, as  FIG. 3  shows, the guide hole  20  is at the top. The cable  26  then hangs down under gravity and secures the plug body  27  in the end position shown. 
       FIG. 3  shows that a further possibility for securing the plug body  27  in the end position can be provided by means of a latching device. This is shown in  FIG. 3 . A longitudinal groove  42  is arranged on the cylinder surface  38 . The cylinder chamber  35  has a rib  43  which projects inwards. In the rotational position of the plug body  27  corresponding to the end position, which is shown in  FIG. 3 , the rib  43  latches into the longitudinal groove  42 , for which purpose the material of the retaining body  12  or of the plug body  27  is of appropriate elasticity. 
     A sprung ball, for example, which latches into the longitudinal groove  42 , can also be provided instead of the rib  43 . Other securing latching devices are possible at this point. For example, a clamp (not shown), into which the cable  26  can be latched in the position shown in  FIG. 3 , that is to say in the end position of the plug body  27 , can be attached to the retaining body  12 . 
       FIG. 5  shows the arrangement of  FIG. 3  in the section according to Line  4 - 4 . Here, the plug body  27  has been removed from the plug receptacle  34  and shown separately to improve clarity. 
       FIG. 1  shows that, in the region of the retaining body  12 , the electrode arrangement  6  runs parallel to and at a distance from the guide tube  3 . This distance should be as small as possible for a number of design reasons. 
     Therefore, as  FIGS. 2 to 5  show, the electrode mounting  22  is not arranged on the cylinder axis of the cylinder surfaces  38  and  39  of the plug body  27  but is offset with respect thereto towards the guide hole  20 . The parallel distance between them is thereby reduced. 
       FIG. 5  shows that, before being inserted into the electrode mounting  22  in the plug body  27 , the end region  21  of the electrode arrangement  6  must pass through another hole  45  in the retaining body  12 . This is only in line with the electrode mounting  22  in the plug body  27  in its end position and not in the position which is rotated through 90° in which the plug body  27  can be fed through the slot  36 . 
     The result of this is that the end region  21  of the electrode arrangement  6  can only be inserted into the electrode mounting  22  in the plug body  27  when the plug body is in its end position. 
     A plug body  27  is shown in  FIG. 4B  in an embodiment in which the electrode mounting  22  lies exactly on the cylinder axis of the cylinder surfaces  38  and  39 . In this case, the hole  45  shown in  FIG. 5  must of course also be appropriately offset. 
     This results in a somewhat less favorable, larger distance between the electrode arrangement  6  and the guide tube  3 . However, a design option is then provided for opening the electrode mounting  22  on the outside by means of a slot  46 . There is therefore the possibility here of first fitting the electrode arrangement and only then inserting the plug body  27 . When the plug body  27  is inserted, the slot  46  slides over the end region  21  of the electrode arrangement  6 , which is located centrally in the cylinder chamber  35  of the plug receptacle  34 . The plug body  27  can then be rotated about the end region  21  which lies on the cylinder axis.