Abstract:
The spacer serves for limiting the depth of insertion of a shaft of a medical instrument into a body of a patient. The spacer has a distal abutment for bearing on a body of a patient. The spacer has a spacer element extending along a length section of the shaft of the medical instrument. A device for releasably mounting the spacer on the shaft has an aperture via which the spacer can be mounted laterally to the shaft. For it the aperture is designed as a lateral slit aperture.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates to a spacer for limiting the depth of insertion of a shaft of a medical instrument into a body.  
         [0002]     In minimally invasive surgery, medical instruments have become established that can be introduced into the body through a small incision, for the purpose of carrying out an intervention in the interior of the body.  
         [0003]     The medical instruments have a shaft which is guided through the incision and into the body, for example through the abdominal wall and into the abdominal cavity. Natural orifices such as the vagina or anus can also be used for introducing Instruments of this kind. The shaft itself can be of a solid design, for example in the case of a liver retractor, a trocar mandrel or other maneuvering instruments, or it can be designed as a hollow shaft.  
         [0004]     Different types of instruments for surgeries can be guided through the hollow shaft.  
         [0005]     At the proximal end, the shaft in most cases terminates in a structural part of greater diameter, for example a housing, a handle or the like.  
         [0006]     The shaft has a defined length and can in theory be pushed into the body until the instrument&#39;s structural part of greater diameter at the proximal end comes to lie on the body in the area around the opening, whether an incision or a natural orifice.  
         [0007]     If, during a surgery, instruments are pushed through a hollow shaft that are intended to perform a tissue-removing function at a site within the body, the distance of this site from the outer surface of the body, which outer surface limits the maximum depth of insertion, varies from patient to patient.  
         [0008]     It is of course possible to set certain maximum depths of insertion through the choice of length of the shaft, but the insertion depth is nevertheless a variable parameter depending on the operation, on the anatomical circumstances and in particular also on the size and stature of the patient.  
         [0009]     The surgeon therefore has to take particular care to ensure that the shaft does not go beyond a defined depth of insertion.  
         [0010]     One example is the depth of insertion of the trocar sleeve when fitting a trocar. Trocars usually comprise a hollow shaft which is closed off at the proximal end by a valve housing of greater diameter. To fit the trocar in the body, a pointed trocar mandrel is inserted into the trocar sleeve, the sharp point of the trocar mandrel protruding from the distal end of the trocar sleeve, that is to say of the shaft. This trocar mandrel point is placed on an incision that has previously been made in the body, for example on the abdominal wall, and, by application of a strong pushing movement, the assembly made up of trocar mandrel and trocar sleeve is driven through the abdominal wall Into the abdominal cavity. After this procedure, the trocar mandrel is withdrawn. In doing this, the trocar sleeve can in theory be pushed into the abdominal cavity until the valve housing comes to lie on the abdominal wall. It is not possible to rule out the possibility of the distally protruding trocar mandrel causing injuries inside the body as the trocar sleeve is being driven in. If a trocar mandrel is used which is considerably longer than the trocar sleeve, there is a considerable risk of injury if the trocar mandrel is driven in too far.  
         [0011]     There can be even farther-reaching consequences when using a medical instrument through whose shaft instruments for detaching tissue are guided. An example of such an instrument is a morcellator.  
         [0012]     Such a morcellator is described, for example, by the Applicant under the name “Rotocut” in the catalog Endoworld Gyn 20-1-E/11-2004. A morcellator has a relatively large housing of great diameter in which a motor is received, and, extending from the distal end, there is a hollow shaft which, in the same way as described above in the context of a trocar, can be guided into a body. A cutting tool that can be driven by the motor is received in the shaft, said cutting tool likewise comprising a tube and being provided with a cutting edge about its distal periphery. A gripping tool can additionally be pushed through the tubular cutting tool, for example in order to grip and hold a tissue that is to be detached by the cutter. In the actual process of tissue removal, the morcellator is driven forward by a certain distance that corresponds to the height of the tissue that is to be detached, which height will differ according to the anatomical circumstances and the pathological case in question. Here too, the dexterity of the operating surgeon again dictates how far he pushes the morcellator forward into the body during the tissue removal. Pushing it in too far would mean detaching not only the pathological tissue, but also the subjacent healthy tissue, which of course is to be avoided.  
         [0013]     It is therefore object of the invention to provide a spacer which should also be able to be applied, if appropriate, when the instrument is already inserted in the body.  
       SUMMARY OF THE INVENTION  
       [0014]     This object is achieved by a spacer for limiting the depth of insertion, which has a distal abutment for bearing on the body and a spacer element extending along a length portion and which moreover has a device for releasably mounting the spacer on the medical instrument and comprises an aperture via which the spacer can be mounted on the shaft, the aperture being designed as a lateral slit aperture via which the spacer can be fitted from the side onto the shaft.  
         [0015]     The provision of a spacer now makes it possible in principle to vary the depth of insertion, in particular to limit this depth of insertion. By providing a distal abutment which can come to bear on the body, the depth of insertion of the shaft is limited by the spacer and no longer by other structural parts of the instrument. The spacer comprises a spacer element which extends along a length portion of the shaft and which either itself limits the extent by which the depth of insertion is limited or at least determines this extent via the distal abutment. By providing a device for releasably mounting the spacer on the instrument, the spacer can be fitted on the medical instrument when the need arises. Moreover, the fact that it is releasable means that the spacer can be set to respectively desired spacer positions on the medical instrument, i.e. a position permitting or limiting the different depths of insertion of the shaft. This can be done in steps or also steplessly, so that it can be adapted with the greatest possible variation to the anatomical circumstances in question.  
         [0016]     The provision of the aperture has the advantage that the spacer can be mounted or fitted directly on the structural part of the instrument whose depth of insertion is to be limited, namely on the shaft, so that the extent by which the depth of insertion is limited can be particularly easily ascertained and set. For example, if the shaft has a theoretical depth of insertion of 15 cm, but is only to be pushed in by a maximum of 10 cm, the depth of insertion can be reduced by the required 5 cm by means of suitable positioning of the spacer on the shaft.  
         [0017]     By designing the aperture as a lateral slit aperture, a spacer can be fitted from the side onto the shaft, specifically at any desired time of the procedure.  
         [0018]     This measure has the considerable advantage that the spacer can be fitted onto the shaft even when the medical instrument has already been inserted into the body.  
         [0019]     In another embodiment of the invention, several spacers can be coupled to one another.  
         [0020]     This measure has the advantage that the extent by which the depth of insertion is limited can be modified by coupling several spacers to one another. If we take the above example with the spacer having the lateral aperture, then, after a spacer has been pushed on from the side and the depth of insertion is to be further limited, an additional spacer can simply be pushed on.  
         [0021]     This can either be done by a further spacer being pushed onto the already fitted spacer, or by the latter being briefly removed and coupled to a second spacer and by the assembly of the two or more spacers then being mounted again on the shaft.  
         [0022]     In another embodiment, the abutment is designed as a planar body.  
         [0023]     This measure has the advantage that the insertion procedure does not adversely affect the body, since the forces can be distributed across the planar body. At the same time, even when the insertion movement of the instrument is carried out with relatively great force, it is possible to avoid the instrument being inserted too far as a result of the body tissue being pressed inward.  
         [0024]     In another embodiment of the invention, the abutment is designed as a disk-like body.  
         [0025]     This measure has the advantage that this disk geometry exerts the aforementioned force or abutment resistance very gently.  
         [0026]     In another embodiment of the invention, the spacer element has a first annular flange which projects from the abutment and which merges via a shoulder into a second annular flange of greater diameter.  
         [0027]     This embodiment now opens up the possibility of several such spacer elements simply being coupled to one another or stacked on top of one another. At the same time, by means of the corresponding axial length extension of the second annular flange of greater diameter, it is possible to define very specific reductions of the depth of insertion per spacer element, for example at centimeter intervals or two-centimeter intervals or the like.  
         [0028]     In another embodiment of the invention, the external diameter of the first annular flange corresponds approximately to the clear internal diameter of the second annular flange.  
         [0029]     This measure has the advantage that several such spacer elements of this design can be pushed onto one another and sit relatively firmly on one another. Several spacer elements pushed onto one another then constitute an approximately cylindrical base body which is made up of the respective second annular flanges of greater diameter, and it is only from the uppermost spacer element of the stack that the first annular flange of slightly smaller diameter protrudes, which then merges into the actual abutment, namely the disk-like or planar body.  
         [0030]     In another embodiment of the invention, the clear internal diameter of the second annular flange is chosen such that it can be placed on a corresponding projection on the instrument.  
         [0031]     This measure now has the considerable advantage that a spacer element can be mounted securely such that it sits in a defined position on the instrument.  
         [0032]     Going back to the example with the lateral slit aperture, the spacer can be pushed on from the side at any position along the length of the shaft and, by axial displacement, can be moved in the proximal direction until the second annular flange of greater diameter sits on the corresponding projection on the instrument. If appropriate, further spacer elements can then be fitted onto a spacer element that has already been fitted in this way, or an assembly of several spacer elements fitted on top of one another can also be fitted in the same way. By choice of a suitable dimension, it is possible for the second annular flange of greater diameter to be pushed or clipped onto the projection by overcoming a certain resistance, such that the spacer element fitted in this way sits securely and immovably, but also releasably, on the instrument. This embodiment, that is to say the interaction of the projection and the second annular flange of greater diameter, constitutes part of the device for mounting the spacer on the instrument.  
         [0033]     In another embodiment of the invention, the device for the releasable mounting comprises a locking screw via which a spacer fitted on the shaft of the instrument can be locked on the shaft.  
         [0034]     This measure has the advantage that, after a spacer is located in the desired position, it can be locked in this position via the locking screw.  
         [0035]     In another embodiment of the invention, the width of the slit aperture in the spacer is slightly smaller than the external diameter of the shaft, so that the spacer can be engaged with a press fit onto the shaft.  
         [0036]     This measure has the advantage that the spacer, while still being releasable, can nevertheless be engaged already with a certain press fit.  
         [0037]     Depending on the further design of the device, the spacer can now remain in this press fit on the shaft, if this is sufficient and offers enough resistance against displacement, or, if appropriate, it can be additionally secured by a locking screw. If the press fit is chosen such that the spacer can be pushed onto the shaft from the side, but can still be moved axially along the shaft, this embodiment serves merely to ensure that the spacer can initially be fitted in a captive manner on the shaft and, by displacement, can then be brought, still captive, to the aforementioned projection for example.  
         [0038]     This reveals the variability of the embodiment of the device for releasable mounting, and, by means of this variability and, for example, a suitable choice of material, it is possible to obtain spacers for multiple applications or also only for disposable use.  
         [0039]     It will be appreciated that the aforementioned features and the features still to be explained below can be used not only in the respectively cited combination, but also in other combinations or singly, without departing from the scope of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0040]     The invention is described and explained in greater detail below on the basis of two selected illustrative embodiments and with reference to the attached drawings, in which:  
         [0041]      FIG. 1  shows a plan view of the distal abutment of a first illustrative embodiment of a spacer,  
         [0042]      FIG. 2  shows a side view of the spacer from  FIG. 1 ,  
         [0043]      FIG. 3  shows a cross section along the line III-III in  FIG. 1 ,  
         [0044]      FIG. 4  shows a perspective view of the spacer from  FIG. 1 ,  
         [0045]      FIG. 5  shows a perspective view of three spacers from  FIG. 4  that have been stacked or fitted on top of one another,  
         [0046]      FIG. 6  shows a highly diagrammatic representation, in partial cross section, of a situation in which the spacer shown in  FIGS. 1-4  is to be fitted onto a shaft of a medical instrument in the form of a morcellator, the medical instrument having already been introduced into a body,  
         [0047]      FIG. 7  shows a situation which is comparable to the representation in  FIG. 6  and in which the assembly depicted in  FIG. 5 , made up of three spacers stacked on top of one another, is mounted on the shaft,  
         [0048]      FIG. 8  shows a representation comparable to  FIGS. 6 and 7  and depicting a morcellator onto which a further illustrative embodiment of a spacer in the form of a slit disk is mounted, and  
         [0049]      FIG. 9  shows a plan view of the spacer depicted in  FIG. 8 . 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0050]     An illustrative embodiment of a spacer shown in FIGS.  1  to  4  is designated in its entirety by reference number  10 .  
         [0051]     The spacer  10 , at the distal end, is roughly in the form of a disk  12  in which a laterally opening slit aperture  14  Is formed. The slit aperture  14  has a circular base  16  whose diameter and position are such that the spacer  10  can be pushed from the side onto a shaft  18  of an instrument that will be described below, specifically in such a way that the shaft  18  then comes to lie approximately in the center of the slit disk  12 , as is indicated by the dashed line in  FIG. 1 .  
         [0052]     It will be seen from the side view in  FIG. 2  that a first annular flange  24  extends from the disk  12  and merges via a shoulder  26  into a second annular flange  28  of somewhat greater diameter. These form a spacer element  21  that extends along a length portion  22 .  
         [0053]     It will be seen from the views in  FIGS. 2 and 3  that the external diameter  25  of the first annular flange  24  corresponds approximately to the clear internal diameter  29  of the second annular flange  28 . In this way it is possible to fit or to stack several spacers  10  on top of one another, namely by placing the second annular flange  28  of a spacer  10 ′ onto the first annular flange  24  of a preceding spacer  10 .  
         [0054]      FIG. 5  shows a situation in which a second spacer  10 ′ is fitted onto a first spacer  10 , as shown in  FIG. 4 , and a third spacer  10 ″ is in turn fitted onto the second spacer  10 ′. The respective top face of the uppermost disk-shaped body of a spacer forms a corresponding abutment  20 , as will be described in more detail below with reference to  FIGS. 6 and 7 .  
         [0055]     The spacers  10 ,  10 ′,  10 ″ can be made of plastic, but they can also be made of metal.  
         [0056]      FIG. 6  shows a situation in which the sleeve  42  of a medical instrument  40  is pushed through an incision  78  in the skin  72  of a human body  70  and into a corresponding internal cavity  74 .  
         [0057]     The medical instrument  40  is designed as a morcellator.  
         [0058]     The medical instrument  40  has a sleeve  42  which is designed as a shaft  18 , as has been described above.  
         [0059]     The sleeve  42  has a beveled tip  44  at the distal end. The sleeve  42  is received in a housing  50  whose diameter is a multiple of the diameter of the sleeve  42 . At the proximal end, the housing  50  opens into a rod-shaped handle  52  via which the morcellator can be gripped by hand.  
         [0060]     At the proximal end, the sleeve  42  is provided with an annular projection  46  via which the sleeve  42  can be mounted on the housing  50 . The projection  46  is approximately disk-shaped and has an external diameter  48  which, as will be described below, corresponds approximately to the clear internal diameter  29  of the second annular flange  28  of the spacer  10 .  
         [0061]     A similarly tubular or sleeve-shaped cutting tool  54  whose distal end is provided with a rotary cutter  56  is received in the inside of the sleeve  42 . A forceps  58  is pushed through the inside of the sleeve-shaped cutting tool  54 , its jaw parts  60  and  62  protruding distally from the cutting tool  54  and spreading in a straight line.  
         [0062]     The jaw parts  60  and  62  are used for gripping and holding a portion of tissue  76  that is to be detached, so that, with the jaw parts  60 ,  62  then closed, this gripped area of tissue can be cut off by the cutting tool  54  and, if appropriate, immediately sectioned through the inner cavity. It will be seen from the representation in  FIG. 6  that the sleeve  42  or shaft  18  of the instrument  40  can theoretically be pushed into the body  70  until the distal end of the projection  46  comes to lie on the outside of the skin  72 . In this case, however, the cutting tool  54  would already have passed through the tissue area  76  that is actually to be detached, and it would have penetrated into a subjacent area of healthy tissue  77 , which is not to be detached.  
         [0063]     In order to limit the depth of insertion of the shaft  18  or sleeve  42  of the instrument  40 , one or more spacers  10 ,  10 ′,  10 ″ can now be pushed on.  FIG. 6  shows a situation illustrating how the spacer  10  is guided In a straight line from the side toward the sleeve  42 , specifically until said sleeve  42  comes to lie in the base  16  of the lateral slit aperture  14 , as is shown in  FIG. 1 . Depending on its design, the spacer  10  could now remain in this position, for example if the spacer  10  has to be pushed on from the side with such a press force that it can virtually no longer move axially. This can be achieved by suitable choice of the materials and of the dimensions.  
         [0064]     If the operating surgeon were to push the instrument  40  in with substantial pressure, it would not be possible to rule out the possibility of the spacer  10  being moved along the sleeve  42  in the proximal direction. This-could go so far that the second annular flange  28  of greater diameter comes to sit on the projection  46 .  
         [0065]     It is therefore possible to provide for this to be the case from the outset, that is to say a spacer  10  is applied until it comes to sit on the projection  46 .  
         [0066]     If it is desired to limit the depth of insertion by more than the extent of the length portion  22  (see  FIG. 2 ) of the spacer  10 , an assembly made up of several spacers can be applied, as is shown in  FIG. 7 .  
         [0067]     Here, an assembly as shown in  FIG. 5  has been fitted on the instrument  40 , specifically in such a way that the second annular flange  28  of greater diameter of the lowermost spacer element  10  of the stack sits on the projection  46 . It will be seen from  FIG. 7  that the depth of insertion  80  is correspondingly reduced, namely by an extent that is the sum of the height of the three second annular flanges  28  plus the height of the first annular flange  24  of the uppermost spacer  10 ″ of the stack. This assembly of the three spacers  10 ,  10 ′,  10 ″ now ensures that the instrument  40  can be pushed in exactly to such an extent that only the tissue  76  that is to be detached can be detached, and not the tissue  77  lying below this.  
         [0068]      FIGS. 8 and 9  show a further embodiment of a spacer  90  which has the form of an annular disk  92  provided laterally with a slit aperture  94  whose clear width corresponds approximately to the external diameter of the sleeve  42  of the instrument  40 , which is identical in design to the aforementioned instrument  40 , that is to say is once again a morcellator.  
         [0069]     The body of the annular disk  92  receives a radially extending locking screw  96  which can be screwed into the slit  94  and in this way secures the annular disk  92  in a defined position on the shaft  42 .  
         [0070]     The longitudinal axis of the locking screw  96  is at approximately 90° to the longitudinal axis of the slit aperture  94 .  
         [0071]     By loosening the locking screw  96 , the spacer  90  can be moved in the axial direction along the sleeve  42 , as is indicated by a double arrow  97  in  FIG. 8 . When the desired position is reached, the spacer  90  is fixed by tightening the locking screw  96  at a defined position. It will be noted that the distal face of the annular disk  92  forms an abutment  93 . This abutment  93  then limits the depth of insertion  98  of the sleeve  42  into the interior  74  of the body  70 , as has been described above.