Abstract:
An access cannula for endoscopic operations comprises a cannula tube, a valve body unit having a valve housing and a valve mounted in said valve housing. Said valve body can be be connected releasably as a completely assembled valve body unit to one end of said cannula tube. Said valve of said valve body ensures a tight closure of said cannula tube at said one end, but allows an instrument to be passed through said valve body unit and said cannula (FIG.  1 ).

Description:
[0001]    This application claims priority of pending European Patent Application No. 01114904.4 filed on Jun. 19, 2001.  
           [0002]    The invention relates to an access cannula for endoscopic operations, in particular for arthroscopy.  
           [0003]    Access cannulas for endoscopic operations are generally known.  
           [0004]    In minimally invasive operating techniques, whose application is becoming ever more widespread, such an access is provided using a trocar. A trocar has a sleeve-like or cannula-like hollow tubular body which is introduced into the body, for example through the abdominal wall, in order to perform operations within the peritoneal space. Suitable instruments, for example endoscopes, are then guided through the trocar in order to be able to visually monitor the operation being performed inside the body.  
           [0005]    To bring the trocar in place, a pointed trocar mandrel or core rod is inserted into the trocar sleeve and a skin incision is made in order to introduce the access cannula, in this case the trocar sleeve, into the body.  
           [0006]    In minimally invasive operations on soft tissue parts, for example through the abdominal wall, the trocar can be introduced exactly in the required size.  
           [0007]    But it is much more difficult to create an access in arthroscopic procedures. If a minimally invasive endoscopic operation is to be performed in a joint, the spaces between two bones forming a joint are often very small, with the result that a trocar cannot easily be fitted using the technique described above.  
           [0008]    It is often desirable or even necessary to arrange a plurality of access cannulas in the operating field in order either to observe the operating field from a plurality of directions or to obtain an access to the joint from a plurality of directions.  
           [0009]    A further problem is that, to permit better viewing of the operating site through the access cannula, gases and/or liquids are introduced in order to slightly expand the body in the operating site by means of overpressure. Irrigation fluids are often also passed through the access cannula. To prevent body fluids, gases or irrigation fluids from running out from the proximal end of the access cannula, a valve is usually provided there which, on the one hand, ensures a tight closure of the cannula tube but, on the other hand, also provides for the possibility of pushing instruments or endoscopes through the valve. Various configurations of valves with flaps or with slit seals are known for this purpose.  
           [0010]    On account of the aforementioned widespread application of minimally invasive surgery, a large number of access cannulas are required which then have to be properly cleaned and sterilized after the surgery, which necessitates the use of high-quality materials.  
           [0011]    It is therefore the object of the present invention to make available an access cannula for endoscopic operations which permits different operating methods and different possibilities of bringing the cannula in place, and which can be produced inexpensively, but nevertheless functions effectively and safely during the intervention.  
         SUMMARY OF THE INVENTION  
         [0012]    The object is achieved by an access cannula which has a cannula tube and a valve housing, which valve housing can be connected releasably to one end of the cannula tube, said valve housing having a valve which ensures a tight closure of the cannula tube at the end but allows instruments to be passed through the cannula tube, and wherein said valve housing is designed as an entire valve body unit, which entire unit is releasable connected to the cannula.  
           [0013]    It is now possible, with one and the same valve body unit, to combine different cannula tubes which are best suited for the particular operating technique. At the same time, this affords the possibility of initially inserting just the cannula tube, and only later securing the entire valve body unit to the latter. This also makes it possible to fit a plurality of cannula tubes which lie close to one another, and are of a very slender construction, without the relatively voluminous valve body being present at the same time. A very high degree of flexibility is thus obtained. It is only when the actual operation is performed, that is to say after the preparation involving placement of the access cannula, that the valve body unit need be connected to the cannula tube and thus ensure a tight closure of this end of the cannula tube. The instruments, for example endoscopes or surgical instruments, can then be pushed through the valve body itself.  
           [0014]    Increased flexibility is also achieved by the fact that other instruments can also be attached for a time to the cannula tube, for which purpose the entire valve body unit is simply removed and an instrument, e.g. a viewing optic or the like, can be attached for a time.  
           [0015]    It is therefore also possible, depending on the objective and on the operating technique, to arrange different cannula tubes on a single type of a valve body unit which has standardized couplings for other instruments.  
           [0016]    This not only increases flexibility but also ensures a considerable reduction in cost and guarantees a perfect sealing. The releasable connection between valve body unit and cannula tube can be effected in different ways, for example by means of a screw connection, a bayonet lock, a snap-fit connection, etc.  
           [0017]    In a further embodiment of the invention, the valve housing is designed as a sterilizable component part which can be used a number of times.  
           [0018]    This measure has the advantage that the aforementioned configuration affords the possibility of producing the valve housing as a high-quality component part, for example made of medical grade steel, which can be sterilized and can be used a number of times.  
           [0019]    In a further embodiment of the invention, the cannula tube is designed as a disposable component part.  
           [0020]    This measure, in particular together with the aforementioned measure, has the advantage that the cannula tube can be produced as an inexpensive disposable part for single use, to which the reusable valve body unit can then be coupled.  
           [0021]    In a further embodiment of the invention, the valve is designed as a double-disk valve.  
           [0022]    This measure has the advantage that, by means of the double-disk construction, an instrument has to be guided through two disks, which ensures particularly reliable sealing.  
           [0023]    In a further embodiment of the invention, a slit seal is provided in each disk.  
           [0024]    This measure has the advantage that instruments of different diameter can be guided through, with a tight closure being ensured in each case. This is especially the case because the valve is designed as a double-disk valve.  
           [0025]    In a further embodiment of the invention, the slits are designed in a star shape, and the slits of the two disks are offset in relation to one another.  
           [0026]    This measure contributes still further to the excellent tight closure.  
           [0027]    In a further embodiment of the invention, the two disks are connected to one another via an elastic bridge.  
           [0028]    This measure has the considerable advantage that the double-disk valve consists only of one component part.  
           [0029]    In a further embodiment of the invention, locking means are provided on the disks and serve to lock the disks onto one another.  
           [0030]    This measure has the advantage that the double-disk valve can be produced as a body which extends in one plane and in which the two disks are connected to one another via the bridge and, for assembly, are turned back and placed one upon the other, by bending the bridge, and are then held firmly on one another by the locking means.  
           [0031]    In a further embodiment of the invention, the valve housing is designed in two parts, and the valve can be arranged between the two parts.  
           [0032]    This measure has the advantage that the valve is held in the valve housing by structurally simple means. This measure also permits simple dismantling of the valve housing for cleaning and sterilizing.  
           [0033]    In a further embodiment of the invention, the valve housing has a main body which has a neck for releasable connection to the cannula tube and moreover has a recess into which the valve can be inserted, the valve being fixed via a clamping ring.  
           [0034]    This measure has the advantage that the main body of the valve housing and the clamping ring can be made from high-quality special steel materials, whereas the interposed valve can be made as a disposable part. For this reason, only these two parts need to be sterilized, and a new valve can be inserted after sterilization.  
           [0035]    This increases the versatility still further and also contributes to a cost reduction. In this case, both the cannula tube and the valve can be designed as a disposable part, and only the two-part valve housing is made of high-quality and precision-finished materials.  
           [0036]    In a further embodiment of the invention, the cannula tube has, at the distal end, a ring which widens conically in the proximal direction.  
           [0037]    This measure has the advantage that the cannula tube can be pushed via this ring into the joint, specifically in arthroscopic operations, and secured against removal or inadvertent loosening during the operation since the distal tip with the conical ring is as it were snapped into the joint.  
           [0038]    In a further embodiment of the invention, the cannula tube is designed as a component part of a trocar device.  
           [0039]    This measure has the advantage that it permits a flexible attachment to different trocars, for example for adults, for children, for thin and for thickset individuals.  
           [0040]    In a further embodiment of the invention, the trocar device has a mandrel with a hand grip and also a core rod, which mandrel can be introduced into the cannula tube.  
           [0041]    This measure has the advantage that the access cannula is designed as it were as a trocar sleeve which is introduced into the body together with the mandrel and core rod.  
           [0042]    In a further embodiment of the invention, the cannula tube is designed as a component part of a dilatation device.  
           [0043]    This measure has the considerable advantage that, upon access, dilatation can be performed without causing trauma. For example in arthroscopic operations, a first access is initially made with very thin cannulas, this access is then widened by pushing on dilatation rods of ever increasing diameter, and, finally, the access cannula according to the invention is fitted as an operating cannula which remains in the body.  
           [0044]    For this purpose, the dilatation device particularly advantageously has a puncture needle, a guide wire, at least one dilatation mandrel for attachment onto the guide wire, the cannula tube being designed in such a way that it can be pushed onto a dilatation mandrel.  
           [0045]    This arrangement is of advantage particularly in terms of the atraumatic placement of the cannula tube for an arthroscopic operation, this versatility having an especially favorable effect in this case. The guide tube can be pushed onto the dilatation mandrel again by means of the mandrel provided with a hand grip.  
           [0046]    It will be appreciated that the features mentioned above and those still to be discussed below can be used not only in the respective combination mentioned but also in other combinations or in isolation, without departing from the scope of the present invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0047]    The invention is described and explained in greater detail below on the basis of a number of selected illustrative embodiments and with reference to the attached drawings, in which:  
         [0048]    [0048]FIG. 1 shows a longitudinal section through an access cannula according to the invention, consisting of cannula tube and valve body unit, in an exploded view;  
         [0049]    [0049]FIG. 2 shows a cross section through the valve body unit, turned through 90° about the axis of the cannula tube;  
         [0050]    [0050]FIG. 3 shows a perspective view of the valve incorporated in the valve housing;  
         [0051]    [0051]FIG. 4 shows the double-disk valve from FIG. 3 in the opened-out state before being fitted in the valve housing;  
         [0052]    [0052]FIG. 5 shows a corresponding perspective view of the valve turned through 180°;  
         [0053]    [0053]FIG. 6 shows a longitudinal section, corresponding to FIG. 1, of the cannula tube and valve body unit when fitted together;  
         [0054]    [0054]FIG. 7 shows a mandrel, with hand grip, of a trocar device;  
         [0055]    [0055]FIG. 8 shows a core rod of a trocar device which is intended to cooperate with an access cannula according to the invention in FIG. 6;  
         [0056]    [0056]FIG. 9 shows the component parts from FIGS. 6, 7 and  8  when fitted together;  
         [0057]    [0057]FIG. 10 shows a puncture needle of a dilatation device;  
         [0058]    [0058]FIG. 11 shows an inner part of the puncture needle from FIG. 10;  
         [0059]    [0059]FIG. 12 shows a guide wire which can be pushed into the puncture needle in FIG. 10;  
         [0060]    [0060]FIG. 13 shows a dilatation mandrel and handle which can be pushed over the guide wire from FIG. 12; and  
         [0061]    [0061]FIG. 14 shows an assembly consisting of the access cannula from FIGS. 1 and 6, with a mandrel from FIG. 7 inserted therein, so as to be pushed over the dilatation mandrel from FIG. 13. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0062]    An access cannula shown in FIG. 1 is provided overall with the reference number  10 .  
         [0063]    The access cannula  10  consists of a cannula tube  12  and of a valve body unit  14 .  
         [0064]    The cannula tube  12  has a tube  16  at whose distal end a conical ring  18  is provided as nose. The conicity is chosen such that the ring  18  widens as viewed from distal to proximal.  
         [0065]    A shoulder  20  is thus created at a distance from the distal end. This ring  18  serves to be driven into a body opening, for example into a joint, and is then locked therein in order to secure against removal of the cannula tube  12 .  
         [0066]    Provided in the area of the conical ring  18 , in the lateral wall, there is a through-opening  22  which serves to permit pressure compensation with the environment during operations. At the end  23  remote from the conical ring  18 , the tube  16  is provided with a collar  24  of greater diameter which has an internal thread  26 .  
         [0067]    The valve body unit  14  is designed as a two-part valve housing. One part is provided by a main body  28  from one side of which there protrudes a tubular neck  30 , which is provided with an external thread  32 . The external thread  32  is configured such that it can be turned into the internal thread  26  in the collar  24  of the tube  16 . The clear internal diameter of the neck  30  corresponds to the clear internal diameter of the tube  16 . Protruding laterally from the main body  28  there is an attachment piece  34  which is closed by a cap  36 . This lateral attachment piece  34  is used to deliver fluids or gases laterally via the valve body unit  14  to the tube  16  or to remove them from it.  
         [0068]    A valve  40  is arranged in the valve body unit  14 , proximally of the lateral attachment piece  34 . The valve  40  thus ensures a tight closure of the valve body unit  14  in the proximal direction and of the cannula tube  12  when the valve body unit  14  is connected to it via the screw connection.  
         [0069]    The valve  40  in this case consists of a double-disk valve  42 , as can be seen in particular from FIGS. 2 through 5.  
         [0070]    The double-disk valve  42  has two disks  44  and  46 , each surrounded by a ring  45  and  47 , respectively. A star-shaped slit  48 ,  50  with three arms is provided in each disk  44 ,  46  respectively. The material of the double-disk valve is a rubber-elastic synthetic material so that, despite the presence of the slits  48  and  50 , a tight closure is guaranteed by each disk  44  and  46 .  
         [0071]    The two rings  45  and  47  are connected to one another via a flexible bridge  52 . From the perspective views in FIGS.  4  and  5 , it will be seen that the slits  48  and  50  are cut so as to be offset in relation to one another.  
         [0072]    As will be seen in particular from FIG. 4, a stud  54  projects from each disk and can be fitted into a corresponding opening  56  on the other disk.  
         [0073]    The double-disk valve  42 , in the configuration represented in FIGS. 4 and 5, can thus be produced as a shaped part or punched-out part, and it is later brought into the position shown in FIG. 3 by bending it about the bridge  52 .  
         [0074]    The valve  40  is inserted into a recess  58  in the main body  28  of the valve body unit  14 , the latter having a lateral slot opening  60  from which the bent bridge  52  can laterally extend. The valve  40  is held on the valve body unit  14  via a clamp ring  62 , which provides a second part of the two-part valve housing. The clamp ring  62  is provided with an external thread which can be turned into an internal thread (not specifically shown) in the recess  58 . The clamping ring  62  then presses the two rings  45  and  47  of the disks  44  and  46  tightly against one another so that a tight closure of the valve body unit  14  is guaranteed by the valve  40  as a whole. The two parts, i.e. main body  28  and clamp ring  62 , provide the two-part valve housing.  
         [0075]    Inside the valve body unit  14  there is a through-opening  64  whose clear internal diameter is greater than the clear internal diameter of the tube  16 , so that for example instruments, e.g. endoscopes or the like, can then be attached to the valve body unit  14 .  
         [0076]    In FIG. 6, the access cannula  10  is shown in the assembled state, i.e. the valve body unit  14  is mounted in place and ready, i.e. the valve  40  is fitted, and the valve body unit  14  is screwed via its external thread  32  on the neck  30  into the internal thread  26  on the collar  24  of the cannula tube  12 .  
         [0077]    In this state, the access cannula  10  can for example be a structural part or component part of a trocar device  70 , as is shown in FIGS. 7 and 8.  
         [0078]    The trocar device  70  thus has a mandrel  72  and a core rod  73  which has a sharpened tip  74 .  
         [0079]    The mandrel  72  has a hand grip  78  from which a tubular sleeve  76  projects.  
         [0080]    The external diameter of the sleeve  76  is chosen such that this corresponds to the clear internal diameter of the tube  16  of the access cannula  10 .  
         [0081]    The trocar device  70  is shown in its assembled state in FIG. 9, i.e. the core rod  73  is pushed into the sleeve  76  of the mandrel  72 , and this assembly is in turn pushed into the cannula tube  12 .  
         [0082]    From the view in FIG. 9, it will be seen that the tip  74  extends slightly beyond the sleeve  76 , and the latter in turn extends beyond the conical ring  18  and is provided with a corresponding conical bevel. This results in the insertion end of the trocar device  70  having a pointed cone shape.  
         [0083]    To insert the access cannula  10 , which now functions as a trocar sleeve, the core rod  73  is applied to a skin incision and pushed into the body, and the whole assembly in FIG. 9 is driven to the desired depth into the body. The hand grip  78  facilitates this procedure. Mandrel  72  and core rod  73  are then removed. By virtue of the valve body unit  14  with the closed valve  40 , it is possible to prevent the escape of body fluids or the like.  
         [0084]    It is also possible to initially insert the cannula tube  12  into the body without having the valve body unit  14  mounted, and to screw the valve body unit  14  later onto it.  
         [0085]    As has already been described, it is also possible to drive the assembly, as shown in FIG. 6, into place and, after removal of mandrel  72  and core rod  73 , if necessary to remove the valve body unit  14  for a short time in order, for example, to fit a second access cannula in the immediate proximity.  
         [0086]    This affords a particularly high degree of versatility.  
         [0087]    After removal of the access cannula  10 , the valve body unit  14  can be dismantled, cleaned and sterilized, and, depending on its design, the double-disk valve  42  can likewise be cleaned and reinserted or can be replaced by another one.  
         [0088]    Depending on its design, the cannula tube  12  can also be cleaned and sterilized, or it can also be made as a disposable part and discarded after the operation. The cleaned, sterilized and reassembled valve body unit  14  can then be again connected to a cannula tube  12 .  
         [0089]    FIGS.  10  to  14  show another possible use of the access cannula  10  according to the invention, involving an access for an arthroscopic operation, for example an operation on a shoulder joint. For this purpose, the puncture needle  82  shown in FIG. 10 is placed at the location where access is required between two bones of the joint. The diameter of the puncture needle  82  is extremely small and is in the range of approximately 1.5 mm.  
         [0090]    The needle is advanced through the skin and into the joint until the needle tip can be detected by an arthroscope.  
         [0091]    An inner part  84  extends through the puncture needle  82  which is designed as a hollow needle.  
         [0092]    After inserting the puncture needle  82  into the joint, the inner part  84  is removed and a guide wire  86  is pushed fully into the puncture needle  82 .  
         [0093]    The puncture needle  82  is then removed, and the guide wire  84  now extends in the body or joint.  
         [0094]    After making a skin incision, a dilatation mandrel  88  is placed on the guide wire  86  and for this purpose, as is shown in FIG. 13, is connected to a hand grip  92 . The connection between hand grip  92  and dilatation mandrel  88  is effected via a locking screw  94 . Depending on the expansion diameter which is desired, one or more dilatation mandrels  88  of ever increasing diameter are pushed on.  
         [0095]    In the illustrative embodiment shown, only the dilatation mandrel  88  is initially pushed onto the guide wire  86  and pressed into the joint, this being made easier by the conical tip of the dilatation mandrel  88 .  
         [0096]    The external diameter of the dilatation mandrel  88  corresponds to the clear internal diameter of a sleeve  76  of a mandrel  72  which is in turn inserted into the tube  16  of an access cannula  10  according to the invention.  
         [0097]    This assembly is shown in FIG. 14.  
         [0098]    After placement of the dilatation mandrel  88 , the hand grip  92  is removed by releasing the locking screw  94 , and the assembly in FIG. 14 is pushed over the dilatation mandrel  88 . The access cannula  10  is again pushed in until its conical ring  18  has snapped into or locked in the joint. To do this, considerable forces have to be applied, and the hand grip  78  makes it possible to do this safely in particular because of its easy-to-grip shape.  
         [0099]    The dilatation mandrel  88  and the mandrel  72  are then removed, and only the access cannula  10  shown in FIG. 6 is left in the body. The actual surgical intervention can then be performed by guiding the appropriate instruments through the cannula.