Abstract:
A trocar mandrel comprises a head, a first mandrel having an elongated shaft, a proximal end of said first mandrel being mounted at said head. At least a second trocar mandrel having an elongated shaft is mounted at said head. Said mandrels are mounted at a distance one to another and project from a distal face of said head.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a trocar mandrel. 
     Trocar mandrels of this kind are in widespread use in minimally invasive surgery and are known, for example, from the catalogue Laparoskopie [Laparoscopy], 3rd edition 2/99, page TROC 20 B, from Karl Storz GmbH &amp; Co KG, Tuttlingen, Germany. 
     A trocar is composed of a trocar sleeve and of a trocar mandrel that is to be pushed into the latter. The trocar mandrel is dimensioned such that it fills the interior of the trocar sleeve, and such that its tip extends distally beyond the trocar sleeve. It is known to give the tip of the trocar mandrel different geometries, for example a blunt tip, a conical tip or a three-edged tip. 
     The assembled device made up of trocar sleeve and trocar mandrel, i.e. the trocar, is used to create an access to an internal cavity of the body in minimally invasive surgery. 
     A widespread area of application is laparoscopy. 
     In laparoscopy, an incision measuring approximately 1 to 2 cm in length is made in the skin of the abdominal wall. The trocar is applied to this incision via the tip of the trocar mandrel protruding from the trocar sleeve. The assembled device is then pushed through the abdominal wall until the distal end of the device protrudes into the abdominal space. The trocar mandrel is then withdrawn and discarded. 
     The hollow trocar sleeve now engages in the body, for example in the abdominal wall, and a minimally invasive intervention can then be performed through the trocar sleeve. 
     The external diameter of a trocar sleeve is up to about 25 mm, such that the space for passing instruments through the trocar sleeve is relatively small. 
     In minimally invasive interventions, it has become customary, particularly in laparoscopy, to apply several such trocar sleeves. In this way, different medical instruments can then be inserted through the several trocar sleeves, for example instruments having purely a monitoring purpose, e.g. endoscopes, and medical working instruments, such as forceps, scissors, punches and the like, and also instruments for supplying media, for example gaseous media for inflating the abdominal space, or irrigation liquids for flushing blood, in particular, from the operating site. 
     In a number of operating techniques, it has been found to be expedient for two adjacent trocars to be inserted at a very defined distance from each other into the body. This is especially the case when a monitoring instrument pushed through a first trocar sleeve is intended to specifically monitor the working area of another instrument that is pushed through a second trocar sleeve. 
     The operator needs to have considerable experience to apply two or more trocars at an exactly defined distance from each other. 
     It is, therefore, an object of the present invention to provide a trocar system allowing to set several trocars at defined distances. 
     SUMMARY OF THE INVENTION 
     According to the invention, the object is achieved by a trocar mandrel, comprising a head, a first mandrel having an elongated shaft, a proximal end of said first mandrel being mounted at said head, said shaft having a tip at its distal end, at least a second trocar mandrel having an elongated shaft, a proximal end of said second mandrel being mounted at said head part, said first and second mandrels are mounted at a distance one to another and project from a distal face of said head. 
     In the simplest case, a second elongated shaft-like mandrel is provided, thereby resulting as it were in a twin trocar mandrel, in which the two shaft-like mandrels are arranged on one and the same head and extend away from the latter. It is possible in principle for more than two mandrels to be arranged on one head. 
     It is thus possible to arrange these mandrels in a very defined orientation, in most cases parallel to each other and at a very defined distance from each other. It is possible to have the mandrels slightly tilted, as long as the mandrels can be pushed into a body with one movement. 
     A trocar sleeve can now be pushed over each of the mandrels, and the resulting trocar is then an assembled device comprising a single head from which there extend several mandrels, onto each of which a trocar sleeve is pushed. 
     In laparoscopy, for example, this compact assembled device can be placed on the corresponding incisions in the abdominal wall and, in a single step, pushed through the abdominal wall. A further advantage is that the necessarily relatively large head of the trocar mandrel can function as a “pusher”, via which the operating surgeon&#39;s hand applies to the trocar the force that is needed to drive the latter through the abdominal wall. 
     After application, the trocar mandrel can then be withdrawn in one step from the correspondingly applied trocar sleeves, whether there are two, three or more of these. 
     The trocar sleeves now remaining in the body are precisely oriented and, in particular, are at the desired defined distance from each other. 
     This considerably facilitates the minimally invasive intervention that is performed through several trocar sleeves. A further advantage is also that such a trocar, having a trocar mandrel according to the invention with several mandrels, constitutes a relatively compact and slim structure that can be inserted initially into already existing body cavities and only then is driven onwards through the tissue into body cavities lying further to the inside. 
     This is very advantageous, for example, in operating techniques practiced in the lower region of the female abdomen, where the trocar with the several trocar sleeves can initially be pushed through the vagina and, only in the area of the uterus or, for example, of the recto-uterine pouch, can be driven through the tissue into the inner body cavity. 
     This can be done much more easily and in a single step compared to a situation where several individual trocars are guided in succession through the vagina as far as these internal tissue regions. In the final analysis, therefore, the trocars can also be applied in a manner that is much less traumatic for a female patient. 
     In another embodiment of the invention, the mandrels have different diameters. 
     This measure has the advantage that different trocar sleeves that are suitable for one type of operation and that have different diameters can be used simultaneously. For example, a trocar sleeve with a relatively large diameter can be applied through which relatively bulky working instruments are pushed, and at the same time a relatively slim trocar sleeve of smaller diameter can be applied through which only a monitoring instrument, e.g. an endoscope, is pushed. 
     This permits a high degree of flexibility and a particularly atraumatic application of trocar sleeves of different diameter. 
     In another embodiment of the invention, the head has a proximal cover surface serving as a grip. 
     This measure has the advantage that this proximal cover surface can serve as an engagement surface, for example for a hand of the operating surgeon, in order to exert the force needed to push the trocar through the tissue. 
     In another embodiment of the invention, the head, seen towards the proximal cover surface, is designed as a rounded body. 
     This measure has the advantage that the head is designed particularly ergonomically, i.e. without corners and edges, such that it can be gripped particularly ergonomically by the operating surgeon. 
     In another embodiment of the invention, a circumferential profile of the cover surface corresponds to a contour line enveloping the mandrels. 
     This measure has the advantage that, here too, a particularly ergonomic and rounded body is created. At the same time, in the case of trocar mandrels with mandrels of different diameter, this results in a contour line that is visible in each case from the outside and that shows the operating surgeon on which side the mandrel of greater diameter is arranged and on which side the mandrel of smaller diameter is arranged. 
     Returning to the previously mentioned example of transvaginal insertion, a considerable portion of the elongate body is already inserted into the vagina shortly before the trocar is pushed into the tissue, and this portion cannot therefore be seen, or can be seen only with difficulty, from the outside by the operating surgeon. This particular contour line now provides the operating surgeon with an indicator of where on the head the mandrel of greater diameter sits and where the mandrel of smaller diameter sits. The same applies when, for example, three such shaft-like mandrels are provided, and the envelope curve is then designed, for example, as a rounded triangle or as a kind of V-shaped or kidney-shaped body, which is correspondingly rounded. Here too, the operating surgeon always has an indication of where the mandrels extend, even when he barely sees them. 
     In another embodiment of the invention, at least one mandrel is mounted releasably on the head. 
     This measure has the considerable advantage that a mandrel that is present can be replaced by another one. This is advantageous, for example, if mandrels of different lengths are to be used. Thus, in laparoscopy, the depth of penetration in a fully grown adult is different than in the case of a child of small frame, for example. However, it is not only possible to use mandrels with different lengths but also, as was mentioned at the outset, with different tip geometries, depending on what is best for the intervention. It is also possible in principle for trocars with different shaft diameters to be exchanged, in which case corresponding measures have to be taken to ensure that these replacement mandrels also fit securely on the head. 
     In another embodiment of the invention, the at least one releasable mandrel can be connected releasably to the head via a locking mechanism, wherein an actuating element is arranged on the head and permits release of the locking mechanism between the head and the mandrel. 
     This measure has the advantages that the replacement procedure is easy to carry out and that, by virtue of the locking mechanism, the mandrel fits on the head sufficiently securely and cannot come loose. There are various design options here, for example ball-type locks or the like, as are used in instrument design for releasable connection between a shaft-like body of this kind and a base structure. 
     In another embodiment of the invention, an adjustment mechanism is arranged on the head and allows the distance between adjacent mandrels to be changed. 
     This measure has the considerable advantage that the distance between the mandrels mounted on the head can be changed, such that it is possible to adapt in a particularly flexible manner to particular situations. 
     In combination with the embodiment of the releasable mandrel, a large number of embodiments and structures can now be achieved that are all mounted on one and the same head of the trocar mandrel. These can be mandrels with differently configured tip geometries, different lengths, different diameters, different shaft geometries or the like. 
     In another embodiment of the invention, on the side of the head from which the shaft-like mandrels protrude, abutments are arranged which limit a depth of insertion of the respective mandrel in a trocar sleeve. 
     This measure has the advantage that the trocar mandrel can be pushed into the trocar sleeve or, conversely, that the trocar sleeve can be pushed onto the mandrel, only as far as the abutment. This gives the operating surgeon a tactile indication that the assembled device made up of the respective trocar sleeve and of the corresponding mandrel has been obtained with the correct relative position of these two structural parts. 
     In another embodiment of the invention, an abutment is designed as a stub which projects from the head and in which a proximal area of the mandrel is received. 
     In the case of mandrels with a relatively large diameter, this measure has the advantage that a relatively bulky mandrel of this type is held particularly firmly and securely by the stub. Since the stub has to be made with a correspondingly larger diameter, the body of the stub can at the same time be designed as such an abutment, for example the distal front edge thereof. 
     In another embodiment of the invention, openings are recessed in the head, in which openings a proximal end section of a mandrel can be received. 
     This measure has the considerable advantage that the connection between head and mandrel can be made over a relatively great length and therefore stable. 
     In embodiments in which the mandrels are connected fixedly to the head, they can be screwed in via threads, adhesively bonded or also welded, for example. In embodiments with exchangeable mandrels, these openings at the same time provide guides, such that the exchangeable shaft, or the distal end thereof, can be guided specifically, for example, to a locking mechanism or releasable coupling. 
     It will be appreciated that the aforementioned features and the features still to be explained below can be used not only in the cited combinations but also in other combinations or singly, without departing from the scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described and explained below on the basis of a number of selected illustrative embodiments and with reference to the attached drawings, in which: 
         FIG. 1  shows a perspective view of a first illustrative embodiment of a trocar mandrel according to the invention, with two mandrels arranged at a distance from each other and having different diameters, 
         FIG. 2  shows a partial longitudinal section through the trocar mandrel from  FIG. 1 , 
         FIG. 3  shows a perspective view of two trocar sleeves that can be pushed onto the two mandrels as are shown in  FIG. 1 , 
         FIG. 4  shows a perspective view of an assembled device made up of the trocar mandrel from  FIG. 1  and the two trocar sleeves from  FIG. 3  to give the resulting trocar, 
         FIG. 5  shows a plan view of the proximal cover face of the trocar mandrel from  FIG. 1 , 
         FIG. 6  shows a corresponding plan view of a second illustrative embodiment of a trocar mandrel with three mandrels, 
         FIG. 7  shows a side view of a third illustrative embodiment of a trocar mandrel in a similar design to the trocar mandrel from  FIG. 1 , except that one of the two mandrels is mounted releasably on the head, 
         FIG. 8  shows a view of the trocar body from  FIG. 7  partially in longitudinal section, with a mandrel released from the head, 
         FIG. 9  shows a plan view of the proximal cover surface of the head of a fourth illustrative embodiment of a trocar mandrel, with an adjustment mechanism for changing the distance between two mandrels, in a state with a minimum distance A between the two mandrels, 
         FIG. 10  shows a side view of the trocar mandrel from  FIG. 9 , 
         FIG. 11  shows a plan view comparable to the view in  FIG. 9 , with the distance between the two mandrels having been increased to a maximum distance, and 
         FIG. 12  shows a side view corresponding to  FIG. 10 , with the trocar mandrel spaced apart to this maximum extent. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     A first illustrative embodiment of a trocar mandrel is shown in  FIGS. 1 to 5 , said trocar mandrel being designated overall by reference number  10 . 
     The trocar mandrel  10  has a head  12  from which a first mandrel  14  and a second mandrel  16  extend in the same direction and parallel to each other. Each of the mandrels  14 ,  16  has a tip  18 ,  20 , respectively, at the distal end. At the proximal end, as can be seen in particular from the sectional view in  FIG. 2 , the mandrels  14  and  16  are received in openings  22  and  24 , respectively, of the head  12 . A proximal end section  26  of the first mandrel  14  engages in a first opening  22  in the head  12  and is securely anchored there. The external diameter of the first mandrel  14  corresponds to the clear internal diameter of the opening  22 . Securing can be provided by adhesive bonding, welding, or by fixing pins. 
     A stub  30  extends in the distal direction from the head  12  and surrounds the opening  22 . 
     This stub  30  provides an additional support and guide for the relatively large mandrel  14 , which has a diameter  34  of 11 mm, which is larger than the diameter  38  of the second mandrel  16 , which is 5.5 mm. 
     As can be seen from the sectional view in  FIG. 2 , the first mandrel  14  is designed as a hollow body  32 . 
     The second mandrel  16 , with the smaller diameter  38 , is designed as a solid rod  36 , which is welded into the opening  24 . 
     The head  12  has a flat proximal cover surface  40 , as can be seen in particular from the views in  FIG. 2  and  FIG. 5 . The proximal cover surface  40  is closed, and the two mandrels  14  and  16  extend from the opposite distal end  42  of the head  12 . The two mandrels  14  and  16  are thus arranged at a distance A from each other, as indicated in  FIG. 1 . 
     It will be seen from  FIG. 5  that a circumferential profile  52  of the proximal cover surface  40  corresponds approximately to an envelope curve surrounding the two mandrels  14  and  16  of different diameter. 
     This results in a rounded head body  54  that can be gripped particularly ergonomically by hand. The proximal cover surface  40  additionally forms an engagement surface during the handling of the trocar mandrel  10 , as will be described below. 
       FIG. 3  shows a first trocar sleeve  44 , of which the sleeve diameter is such that this first trocar sleeve  44  can be pushed with a matching fit onto the first mandrel  14 . 
     Correspondingly, a second trocar sleeve  46  is designed such that it can be pushed with a matching fit onto the second mandrel  16 . 
     The annular distal front face of the stub  30  forms an abutment  48  up to which the first trocar sleeve  44  can be pushed on. The area of the distal end  42  around the second mandrel  16  then forms an abutment  50  for the second trocar sleeve  46 . 
       FIG. 4  now shows an assembled device in which the first trocar sleeve  44  is pushed onto the first mandrel  14  and the second trocar sleeve  46  is pushed onto the second mandrel  16 . 
     In the assembled state shown in  FIG. 4 , a trocar has now been formed which, over the two mandrels  14  and  16 , has two trocar sleeves  44  and  46  arranged in parallel and at a defined distance from each other. 
     As can be seen from the view in  FIG. 4 , the tips  18  and  20  of the mandrels  14  and  16  protrude from the trocar sleeves  44  and  46  at the distal end. 
     During handling, this assembled device can now be picked up and, for example in a laparoscopic intervention, applied to two incisions on the abdominal wall, with the two tips  18  and  20  being placed on these incisions. 
     By applying pressure to the proximal cover surface  40  of the head  12 , it is now possible to push the trocar through the abdominal wall. After application, the trocar mandrel  10  is withdrawn, and the two trocar sleeves  44  and  46  remain in the abdominal wall, specifically in the desired orientation and especially at the desired distance A from each other. The desired minimally invasive intervention can now be performed through the trocar sleeves  44  and  46 . 
       FIG. 6  shows a plan view of a head  62  of a second illustrative embodiment of a trocar mandrel, which is designated overall by reference number  60 . It will be seen that the head  62  receives a first mandrel  64 , which in size and diameter corresponds approximately to the first mandrel  14  of the first illustrative embodiment. 
     In the second embodiment, a second mandrel  66  and a third mandrel  68  are present, said two additional mandrels  66  and  68  having a smaller diameter than the first mandrel  64 . 
     The distance of the second mandrel  66  from the first mandrel  64  and the distance of the third mandrel  68  from the first mandrel  64  are approximately the same, said distance also corresponding approximately to the distance between second mandrel  66  and third mandrel  68 . The circumferential profile  65  of the head  62  can again be regarded as a kind of envelope line around the three mandrels  64  to  68  and once again results in an ergonomically rounded body  67 . 
     A body  67  of this kind can be safely and ergonomically gripped in one hand, such that a trocar mandrel  60  of this kind, with trocar sleeves pushed onto the three mandrels  64  to  68 , can be manoeuvred safely. Thus, three trocar sleeves can then be placed in the body at a very defined distance from each other and in a very defined geometric arrangement to each other, in this case lying at the corners of what is approximately an isosceles triangle. 
     A third illustrative embodiment of a trocar mandrel, shown in  FIGS. 7 and 8 , is designated overall by reference number  70 . 
     In terms of its main components, the trocar mandrel  70  is of a similar design to the trocar mandrel  10 , i.e. it has a head  72  on which are mounted a first mandrel  74  and a second mandrel  76  of smaller diameter, 
     Thus, the basic design of the head and of the two mandrels  74  and  76  is the same as in the trocar mandrel  10 . 
     In contrast to the first illustrative embodiment, the second mandrel  76  is mounted releasably on the head  72 . For this purpose, a locking mechanism  78  is provided in the head  72  and the second mandrel  76 . 
     This locking mechanism  78  has a circumferential groove  80  on the second mandrel  76 . 
     Several spring-loaded balls  82  are arranged in the opening  81  in the head  72 , into which opening the distal end section of the second mandrel  76  can be pushed, as is indicated by the arrow  91 . 
     These balls  82  sit in lateral recesses and are pressed in the direction of the interior of the opening  81  by the corresponding springs. The position is such that, when the second mandrel  76  is pushed fully into the opening  81 , the balls  82  can engage in the groove  80 . An actuating element  84  serves to release this ball locking mechanism  78 . 
     For this purpose, the actuating element  84  can be moved in the direction of the balls  82  counter to the force of a spring  86 , as is indicated by the arrow  93 . A distal circumferential edge  90  of the actuating element  84  is bevelled, such that a movement of the actuating element  84  in the direction of the arrow  93  counter to the force of the spring  86  presses the ball  82  radially outwards, such that the locking mechanism  78  is then released. 
     At the upper proximal end, the actuating element  84  is designed as a button  88  that protrudes above the distal cover surface of the head  72 , as can be seen in particular from  FIG. 7 . 
     To secure the second mandrel  76  in the head  72 , it is simply pushed into the opening  81 , as can be seen from  FIG. 8 , until the balls  82  engage in the groove  80 . 
     To release it, the button  88  is pressed in, as a result of which the balls disengage and the second mandrel  76  can be removed. 
     With the trocar mandrel  70 , this opens up the possibility of exchanging the second mandrel  76 , for example with a trocar mandrel having a different cross-sectional geometry or having another tip characteristic, another length or the like. 
     In principle, it is also possible, if so desired, for the first mandrel  74  also to be made releasable. 
     In this way, the first mandrel  74  could then also be exchanged, such that it would then be possible, depending on requirements, to exchange only one of the two mandrels or else both mandrels  74  and  76 . 
     In the fourth illustrative embodiment of a trocar mandrel according to the invention, shown in  FIGS. 9 to 12 , the trocar mandrel is designated overall by reference number  100 . 
     The trocar mandrel  100  has a head  102 , which is made up of a first part  104  and of a second part  114 . 
     The first part  104  has a distally projecting stub  106 , in which a first mandrel  108  is inserted. A flat bracket  110 , in which a slit  112  is formed, extends away from the stub  106  approximately at right angles thereto. 
     Approximately in a mirror image to this, a stub  116 , in which a second mandrel  118  is received, likewise extends in the distal direction away from the second part  114 . 
     In this illustrative embodiment, the diameter of the first mandrel  108  and of the second mandrel  118  is equal. A bracket  120 , which has a slit  122 , also extends away from the second part  114 . 
     In the assembled state, and as can be seen in particular from  FIGS. 9 and 11 , the two flat brackets  110  and  120  are laid one over the other, in such a way that the slits  112  and  122  thereof lie one over the other. 
     A tommy screw  124 , which is used to connect these two parts  104 ,  114  firmly to each other, extends through both slits  112 ,  122 . It will be seen from the plan view in  FIG. 9  that a scale  126  is arranged on the top face of the bracket  110 . 
     These structural elements, that is to say brackets  110 ,  120 , slits  112 ,  122  and tommy screw  124 , together constitute an adjustment mechanism  128 . The distance A between the two mandrels  108  and  118  can be changed via this adjustment mechanism  128 . 
     In the view in  FIGS. 9 and 10 , the distance A is the minimum extent of the distance. That is to say, the two brackets  110  and  120  are moved towards each other to the maximum extent and are fixed on each other via the tommy screw  124 . 
     By releasing the tommy screw  124 , it is possible for the two parts  104  and  114 , and the mandrels  108 ,  118  secured thereon, to be changed in terms of distance by being pulled apart, in which connection  FIGS. 11 and 12  now show the maximum distance A+x. It will be seen in particular from  FIG. 11  that, in this position, the tommy screw  124  abuts the right-hand end of the slit  112  and, at the same time, the left-hand end of the slit  122  arranged underneath. 
     Overall, therefore, the distance between the two mandrels  108 ,  118  can be varied between the distance A shown in  FIG. 10  and the distance A+x shown in  FIG. 12 . 
     The scale  126  gives the operator a measure for the shift x. 
     It is also conceivable that, when the tommy screw  124  is released, it is not only possible for the two parts  104 ,  114  to be moved along the longitudinal extent of the slits  112 ,  122 , but also to be angled away from or towards each other and fixed in the angled state. 
     Provision can also be made for the variant shown in  FIGS. 7 and 8 , in which a mandrel is releasable, to be provided also in the fourth illustrative embodiment, such that a particularly high degree of flexibility is achieved as regards the spacing and the configuration of the mandrels to be used.