Abstract:
In order to improve a surgical instrument having at least one tool comprising a carrier and at least one functional component adhesively bonded to the carrier, in such a way that the carrier can be easily and securely adhesively bonded to the functional component, whilst maintaining the desired function of the instrument, it is proposed that the carrier comprise a first contact surface, that the functional component comprise a second contact surface, and that the first contact surface bear on the second contact surface without any gap therebetween.

Description:
[0001]    The present disclosure relates to the subject matter disclosed in German application No. 103 28 512.1 of Jun. 20, 2003, which is incorporated herein by reference in its entirety and for all purposes.  
         BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to a surgical instrument with at least one tool comprising a carrier and at least one functional component adhesively bonded to the carrier.  
           [0003]    Surgical instruments of the kind described at the outset are known, for example, in the form of scissors comprising a metallic or plastic scissor blade to which a ceramic or metal cutter is adhesively bonded. Such a two-part construction of the tool is used, for example, in bipolar instruments, as such instruments require tools which are electrically insulated from one another. When current is passed over the tool during use of the instrument, this may cause evaporation of the adhesive along the cutting edge.  
           [0004]    The object of the present invention is, therefore, to so improve a surgical instrument of the kind described at the outset that the carrier can be easily and securely adhesively bonded to the functional component, whilst maintaining the desired function of the instrument.  
         SUMMARY OF THE INVENTION  
         [0005]    This object is accomplished with a surgical instrument of the kind described at the outset, in accordance with the invention, in that the carrier comprises a first contact surface, in that the functional component comprises a second contact surface, and in that the first contact surface bears on the second contact surface without any gap therebetween.  
           [0006]    With carrier and functional component designed accordingly, such a construction has the advantage that a defined coagulation path is formed along the area of transition between the carrier and the functional component, for example, between a metal and a ceramic material, when the instrument is used as bipolar instrument. Furthermore, when current is passed along the contact surfaces, evaporation of an adhesive cannot occur because adhesive cannot get in between the contact surfaces in this area during the bonding owing to the two contact surfaces bearing on each other without any gap between them.  
           [0007]    It is expedient for the first contact surface to bear directly and/or without any adhesive on the second contact surface. It is thus impossible for the adhesive to evaporate when current is passed over the tool.  
           [0008]    It is conceivable for the instrument to be designed in a multiplicity of ways for different purposes. It could, for example, be designed as forceps, fixation forceps or needle holder, with the at least one tool being constructed accordingly. It is, however, advantageous for the at least one tool to be a scissor blade comprising a cutter, for the cutter to comprise a cutting edge, and for the first and second contact surfaces in the area of the cutting edge to bear directly on each other or continue into the cutting edge. Owing to the functional component bearing on the carrier without any gap therebetween, a precisely defined cutting edge which can be of particularly smooth design without any undesired projections is formed. In particular, no bonding agent, for example, in the form of an adhesive or any other bonding material, such as, for example, soldering tin, can leak in the area of transition between the carrier and the functional component and thereby alter the shape of the area of transition in an undesired manner.  
           [0009]    The first contact surface and the second contact surface preferably bear on each other along at least one contacting line with no gap therebetween. Adhesive introduced between the two contact surfaces in order to join these, is, for example, thereby prevented from forming part of the surface of the tool, in particular, in the area of the cutting edge. In particular, this would have the disadvantage that, if a coagulation current flowed along this surface of the tool, the adhesive could evaporate in an undesired manner and be released in the human body. In addition, damage could be caused to the instrument.  
           [0010]    It is particularly expedient for the first contact surface and the second contact surface to bear surface-to-surface on each other at least section-wise in the area of a common contacting surface with no gap therebetween. In particular, when the two contact surfaces are adhesively bonded to each other, a particularly reliable adhesive-free separation between the two contact surfaces is thereby ensured. Even when particularly large coagulation currents flow along the surface of the tool, evaporation of the adhesive is thereby prevented.  
           [0011]    In accordance with a preferred embodiment of the invention, provision may be made for the carrier to comprise a first adhesive surface, for the functional component to comprise a second adhesive surface, for the first adhesive surface to be separated from the second adhesive surface by an adhesive gap, and for the adhesive gap to be filled with an adhesive layer which is substantially formed by an adhesive. This configuration ensures that the functional component can be bonded in a desired manner to the carrier. The formation of the adhesive gap enables introduction of the adhesive in a defined manner between the two adhesive surfaces of the carrier and the functional component.  
           [0012]    It is particularly advantageous for the adhesive gap to be of wedge-shaped construction at least section-wise. In this way, manufacturing tolerances of carrier and functional component are particularly easy to compensate. Furthermore, the two parts can thereby be made to bear on each other along a contacting line.  
           [0013]    It is expedient for a thickness of the wedge-shaped adhesive gap to decrease in the direction towards the first and second contact surfaces bearing on each other. By virtue of such a construction of the adhesive gap, on the one hand, a secure connection between carrier and functional component is ensured, and, on the other hand, an amount of adhesive between the two parts and adjacent to the contact surfaces bearing on each other without a gap therebetween or adjacent to the contacting line is minimized.  
           [0014]    In accordance with a preferred embodiment of the invention, provision may be made for the first contact surface to define at least section-wise a first plane, for the second contact surface to define at least section-wise a second plane, and for the first plane and the second plane to be inclined at an angle of inclination relative to each other and intersect in a contacting line of the first and second contact surfaces. In this way, for example, a wedge-shaped adhesive gap with the above-described advantages can be formed.  
           [0015]    In order to make the at least one tool as compact as possible, it may be expedient for the angle of inclination to be less than 45°, preferably less than 20°. In particular, with very small angles of inclination in the range of less than 20°, only a minimal amount of adhesive is required for bonding the carrier and the functional component reliably and permanently to each other.  
           [0016]    At least one spacer is preferably arranged in the adhesive gap between the first and second adhesive surfaces. The at least one spacer ensures that the functional component cannot tilt relative to the carrier. This could happen because the carrier and the functional component bear with their two contact surfaces on each other without a gap therebetween, whereas a gap can be formed in the remaining area of the surfaces of the carrier and the functional component that are to be bonded to each other. The at least one spacer thus defines a minimum spacing between the first and second adhesive surfaces, so that the first contact surface and the second contact surface can bear with their entire surface on each other.  
           [0017]    The construction of the instrument becomes particularly simple when the first and/or the second adhesive surface carry the at least one spacer. Thus, for bonding purposes, adhesive can either be injected into the adhesive gap or applied to one or both of the adhesive surfaces before the carrier is brought into contact with the functional component. A desired spacing is automatically maintained between the functional component and the carrier by the at least one spacer.  
           [0018]    Alternatively or additionally, it is conceivable for the adhesive to contain the at least one spacer. Such a configuration has the advantage that both the carrier and the functional component can be manufactured in a particularly simple way, and, in accordance with manufacturing tolerances actually determined after the manufacture of the two parts, spacers having the necessary size can be selected and added to the adhesive, or that an adhesive with corresponding spacers can be directly selected.  
           [0019]    It is expedient for a plurality of spacers to be provided. This results in a plurality of contact points between the functional component, the spacer and the carrier, so that the adhesive gap is formed in a desired manner.  
           [0020]    In principle, a multiplicity of shapes are conceivable for the at least one spacer. It is particularly advantageous for the at least one spacer to be of spherical, pyramidal, conical, cylindrical or parallelepipedal shape. Such shapes can be manufactured in a particularly simple and defined manner.  
           [0021]    In principle, the adhesive surfaces of the carrier and the functional component could be of completely smooth design. In accordance with a preferred embodiment of the invention, provision is, however, made for the surface of at least one adhesive surface to have at least one structured surface portion. Formation of a structure on the adhesive surfaces results in enlargement of these, which contributes towards increasing the adhesive strength between the carrier and the functional component.  
           [0022]    It is expedient for the structured surface portion to essentially comprise a symmetrical structure. Such a configuration is particularly easy to produce. For example, pyramids with different shapes or interlockings could be selected. The structured surface portion can simultaneously serve as spacer.  
           [0023]    Alternatively or additionally, it is also conceivable for the structured surface portion to be microstructured. This could, for example, be accomplished by glass bead matting. In addition, a microstructured surface has the advantage that adhesive molecules can be bonded particularly well to the carrier and/or the functional component.  
           [0024]    To increase the adhesive strength it is advantageous for the surface of the first and/or the second adhesive surface to be larger than a projection of the first and/or the second adhesive surface onto the respective other adhesive surface. Such a configuration ensures that the adhesive surface, as a whole, is enlarged, which increases a surface of application for the adhesive.  
           [0025]    In principle, it is conceivable to bond identical materials to one another. When the instrument is to be used for electrosurgical procedures, it is advantageous for the carrier to be electrically conductive and for the functional component to be electrically non-conductive. In this case, the functional component serves as insulator. A reverse construction of the tool is also conceivable.  
           [0026]    For the construction of scissors, it is expedient for the first tool to be movable, in particular, mounted for pivotal movement, relative to a second tool.  
           [0027]    In order for the instrument to also be usable for endoscopic surgical procedures, provision may be made, in accordance with a preferred embodiment of the invention, for the instrument to be a tubular shaft instrument with an elongated shaft, and for the at least one tool to be movably mounted at the distal end of the shaft.  
           [0028]    It is expedient for the instrument to be scissors. This enables the instrument to be used as, for example, bipolar scissors.  
           [0029]    The following description of preferred embodiments of the invention serves in conjunction with the drawings to explain the invention in greater detail. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0030]    [0030]FIG. 1 is a longitudinal sectional view of scissors according to the invention;  
         [0031]    [0031]FIG. 2 is an enlarged view of detail A in FIG. 1;  
         [0032]    [0032]FIG. 3 is a longitudinal sectional view, turned through 90° in relation to the view in FIG. 2, of scissors with closed scissor blades;  
         [0033]    [0033]FIG. 4 is an enlarged view of a scissor blade;  
         [0034]    [0034]FIG. 5 is a sectional view along line  5 - 5  in FIG. 4;  
         [0035]    [0035]FIG. 6 is a sectional view along line  6 - 6  in FIG. 5;  
         [0036]    [0036]FIG. 7 shows a second embodiment of a scissor blade according to the invention in a view similar to FIG. 6;  
         [0037]    [0037]FIG. 8 shows a third embodiment of a scissor blade in a view similar to FIG. 6;  
         [0038]    [0038]FIG. 9 shows a fourth embodiment of a scissor blade in a view similar to FIG. 5; and  
         [0039]    [0039]FIG. 10 shows a fifth embodiment of a scissor blade in a view similar to FIG. 5. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0040]    A longitudinal sectional view of bipolar scissors generally designated by the reference numeral  10 , constructed as an endoscopic tubular shaft instrument, is shown in FIG. 1.  
         [0041]    The bipolar scissors  10  comprise an elongated, tubular shaft  12 , at the distal end of which two scissor blades  14  and  16  pivotable relative to each other are mounted on a bearing pin  18  which extends through the shaft  12  on either side thereof and transversely to a longitudinal axis  20  of the shaft  12 .  
         [0042]    For moving the scissor blades  14  and  16  a drive member  24  is arranged at a distal end of a push-and-pull rod  22  which is longitudinally displaceable in the direction of the longitudinal axis  20  in the shaft  12 . The drive member  24  is provided with two guide slots  26  in which bearing pins  28  projecting from the scissor blades  14  and  16  transversely to the longitudinal axis  20  engage and are guided as a result of an axial displacement of the drive member  24 , whereby the scissor blades  14  and  16  are opened and closed, respectively.  
         [0043]    At its proximal end  30 , the shaft  12  is accommodated in a longitudinal bore  32  of a stationary handle part  34 , from which a stationary branch  36  with a finger opening  38  extends essentially transversely to the longitudinal axis  20  away from the latter. On the handle part  34 , a second branch  40  is mounted in a recess  42  open in proximal direction for pivotal movement about a bearing bolt  44  extending through the recess  42  transversely to the longitudinal axis  20  and comprises at its free end a further finger opening  46 .  
         [0044]    A proximal end of the push-and-pull rod  22  is provided with a short cylindrical head  48  which engages in a positively locking manner in a bearing groove  50 , expanding with a single step, of a bearing cylinder  52  and is held therein.  
         [0045]    The push-and-pull rod  22 , which is covered with an electrical insulating layer  54 , projects from the bearing groove  50 . A longitudinal axis of the bearing cylinder  52  extends transversely to the longitudinal axis  20 . The bearing cylinder  52  is held on the branch  40  in the proximity of the bearing bolt  44  in a bearing bore  56 , which extends transversely to the longitudinal axis  20  and has a slot  58  expanding in distal direction from the center of the bearing bore  56 .  
         [0046]    As well as the push-and-pull rod  22 , the shaft  12  is surrounded by an electrically insulating layer  60 . Both the shaft  12  and the push-and-pull rod  22  are connected in a manner not shown in detail to a bipolar connection  62 , by means of which the bipolar scissors  10  can be connected by means of lines to an electrical energy supply unit. Via both the push-and-pull rod  22  and the shaft  12 , an electric connection is established to one of the two scissor blades  14  and  16 , respectively, which are insulated relative to each other. This makes it possible, for example, in order to coagulate tissue, to pass a high-frequency current over the scissor blades  14  and  16  and to sever the coagulated tissue following the coagulation procedure.  
         [0047]    Also provided is a rotary knob  64  which is non-rotatable relative to the shaft  12 , but is rotatable relative to the handle part, so that the distal end of the bipolar scissors  10  with the two scissor blades  14  and  16  can be rotated relative to the two branches  36  and  40  about the longitudinal axis  20 .  
         [0048]    [0048]FIG. 2 shows an enlargement of detail A in FIG. 1. The drive body  24 , which is made up of two half shells  66  and  68 , serves to move the two scissor blades  14  and  16 . The two half shells  66  and  68  are of identical construction and are essentially in the form of half a cylinder severed in longitudinal direction. For assembly, the two half shells  66  and  68  each have two pairs of connecting pins  72  projecting in circumferential direction and two pairs of recesses  74  accommodating these. The recesses  74  and the connecting pins  72  are alternately formed along the edge of the half shells  66  and  68  extending parallel to the longitudinal axis  20 . In the assembled state, i.e., in a coupled position, in which the two half shells  66  and  68  are joined to each other and connect the push-and-pull rod  22  to the two scissor blades  14  and  16 , the two half shells  66  and  68  form at the proximal side a rod receptacle  70  in the form of a bore. This tapers with a single step on a short section and then expands again in diameter with a single step, so that a ring projection  76  is formed between the rod receptacle  70  and a ring groove  78 .  
         [0049]    A distal end of the push-and-pull rod  22  has a ring groove  80  which corresponds with the ring projection  76 , and adjoining the ring groove  80  a cylindrical head  82  designed so as to correspond with the ring groove  78 .  
         [0050]    At the distal side the two half shells  66  and  68  are provided with essentially V-shaped recesses  84  and  86  open in distal direction. One of the two guide slots  26  is machined in the direction of the shaft  12  in each recess. The two guide slots  26  form a groove which is open transversely to and towards the longitudinal axis  20 , and in which the bearing pins  28  of the scissor blades  14  and  16  each engage transversely to the longitudinal axis  20  and so as to point away from the longitudinal axis  20 . The guide slots  26  are slightly curved.  
         [0051]    To assemble the front end of the bipolar scissors  10 , the two scissor blades  14  and  16  are first inserted with their bearing pins  28  into the respective guide slots  26  and the push-and-pull rod  22  is placed with its head  82  in the ring groove  78 . The half shells  66  and  68  are pushed together transversely to the longitudinal axis  20  so that each connecting pin  72  of the half shell  66  engages a recess  74  of the half shell  68  and vice versa. The half shells  66  and  68  are not adhesively bonded to each other or undetachably joined to each other in any other way.  
         [0052]    Following the above-described assembly of the parts, the push-and-pull rod  22  is inserted from the distal end into the shaft  12  until the shaft  12  surrounds the half shells  66  and  68 . Once the half shells  66  and  68  are inserted in the shaft  12 , the push-and-pull rod  22  and the scissor blades  14  and  16  are undetachably joined to each other in axial direction as the shaft  12  secures the half shells  66  and  68  against release from the push-and-pull rod  22 . Finally, the bearing pin  18  is pushed through bores  88  extending transversely to the longitudinal axis in the shaft  12 , whereby the scissor blades  14  and  16  are fixed on the shaft  12  and owing to movement of the push-and-pull rod in axial direction and guidance of the bearing pins  28  in the guide slots  26 , only a pivotal movement of the scissor blades  14  and  16  towards each other or away from each other remains possible.  
         [0053]    From FIG. 3 it is evident that the two scissor blades  14  and  16  are slightly curved. It is also shown that the scissor blade  16  on its side pointing in the direction towards the scissor blade  14  is provided with an electrically insulating ceramic layer  90  which forms a functional component. In a similar way, the scissor blade  14  is provided with a ceramic layer  92  pointing in the direction towards the scissor blade  16 .  
         [0054]    Each of FIGS.  4  to  8  shows that the scissor blade  14  in the form of a metallic carrier  94  is adhesively bonded to the ceramic layer  92 . To insulate the two scissor blades  14  and  16  from each other, the ceramic layer  92  is constructed in the area of the bearing pin  18  as a bearing bush  96 , so that a short circuit cannot occur between the carrier  94  of the scissor blade  14  and a metallic carrier  98  of the scissor blade  16 .  
         [0055]    [0055]FIG. 5 shows the special construction of the scissor blade  14  in cross section. Only in the area of a cutting edge  100  do the carrier  94  and the ceramic layer  92  bear directly on each other and hence without any gap therebetween. There is therefore no gap between contact surfaces  102  of the carrier and  104  of the ceramic layer bearing on each other, and so no adhesive can get in between these two layers.  
         [0056]    The further surface of the carrier  94  pointing towards the ceramic layer  92  and not serving as contact surface  102  forms an adhesive surface  106 , the further surface of the ceramic layer  92  an adhesive surface  108 . The adhesive surface  106  of the carrier  94  comprises a flat adhesive groove  110  in which an adhesive projection  112  of the ceramic layer  92  engages, but does not fill this out in a positively locking manner. There is thus formed between the carrier  94  and the ceramic layer  92  an adhesive gap  114  which also surrounds the adhesive projection  112 .  
         [0057]    A suitable adhesive is introduced into the adhesive gap  114  to bond the carrier  94  to the ceramic layer  92 .  
         [0058]    To prevent tilting of the ceramic layer  92  relative to the carrier  94  about an edge  118  of the carrier  94 , which delimits the contact surface  102  towards the adhesive gap  114 , additional spacers  120  in the form of small, elongated, parallelepipedal members having a height which corresponds to the width of the adhesive gap  114  are arranged at regular spacings on the adhesive projection  112  or on one of the adhesive surfaces  106  or  108 . End faces  122  of the spacers  120  then lie directly against the adhesive surface  106  of the carrier  94  without any gap therebetween.  
         [0059]    Alternative embodiments of spacers are shown in FIGS. 7 and 8. In FIG. 7, spacers  124  in the form of small pyramids are integrally formed on the ceramic layer, with apexes of the spacers  124  touching the adhesive surface  106  of the carrier  94  in the form of dots. In this way, with the desired spacing being maintained between the two adhesive surfaces  106  and  108 , the adhesive surface  106  of the carrier  94 , which is covered with adhesive  116 , can be maximized.  
         [0060]    A third variant of a possible spacer is shown in FIG. 8. To maintain the spacing between the adhesive surface  106  of the carrier  94  and the adhesive surface  108  of the ceramic layer  92 , a plurality of balls  126  are mixed with the adhesive  116 , with the diameter of the balls  116  being selected so as to correspond to the desired width of the adhesive gap  114 . Owing to their shape, the balls  126  distribute themselves more or less uniformly between the adhesive surfaces  106  and  108 .  
         [0061]    Furthermore, the adhesive surface  106  and likewise the adhesive surface  108  may, in addition, be structured or microstructured in an optional manner in order to enlarge the surface wetted and covered with adhesive  116 . This is indicated in the cross section in FIG. 5, by way of example, by formation of the adhesive groove  110  and the adhesive projection  112 .  
         [0062]    [0062]FIG. 9 shows a cross-sectional view of a fourth variant of a scissor blade, as described in conjunction with FIGS.  1  to  5 . Elements of the scissor blades which are identical or of very similar construction are, therefore, designated by identical reference numerals with the addition of the suffix “a”.  
         [0063]    A major difference from the embodiment described in conjunction with FIG. 5 is that, strictly speaking, the two contact surfaces  102   a  and  104   a  do not form contacting surfaces, but contacting lines. In this way, as a whole, a common contacting line  103   a  is formed, which closes the adhesive gap  114   a , which tapers in the shape of a wedge in the direction towards the contacting line  103   a , in the area of the cutting edge  100   a . Consequently, when an instrument constructed with the above-described scissor blade is used, a current flowing along a coagulation path  128   a  along the cutting edge  100   a  will not come into contact with the adhesive  116   a  introduced into the adhesive gap  114   a  between the adhesive surfaces  106   a  and  108   a  and bring about evaporation thereof. The two contact surfaces  104   a  and  102   a  are inclined at an angle of inclination  130   a  relative to each other, which has a value of approximately 10°.  
         [0064]    A fifth embodiment of a scissor blade according to the invention is shown in cross section in FIG. 10. As in the embodiment shown in FIG. 9, identical elements or elements similar to those of the embodiment described in conjunction with FIGS.  1  to  5  are designated by identical reference numerals with the addition of the suffix “b”.  
         [0065]    The fifth embodiment corresponds in its basic design to the fourth embodiment, but differs in that the contact surfaces  102   b  and  104   b  are each in the form of two plane surface portions, which results in a surface-to-surface contacting of the two contact surfaces  102   b  and  104   b  starting from the cutting edge  100   b . The contact surface  102   b  is of completely plane design. The contact surface  104   b  has two surface sections which are inclined relative to each other, with the one surface section extending parallel to the contact surface  102   b  and resting thereon, and the other surface section extending through an angle of inclination  130   b  at an incline to the contact surface  102   b , so that here, too, a wedge-shaped adhesive gap can form between the inclined surface sections of the contact surfaces  102   b  and  104   b . In the present embodiment, the angle of inclination  130   b  has a value of approximately 10°. Owing to the surface-to-surface contacting of the contact surfaces  102   b  and  104   b  bearing on each other, a coagulation path  128   b  along the cutting edge  100   b  is even further away from the adhesive  116   b  joining the carrier  94   b  to the ceramic layer  92   b , so that evaporation thereof is virtually impossible.  
         [0066]    The two construction variants, as described in FIGS. 9 and 10, may also be provided with spacers, as explained in further detail in conjunction with FIGS.  6  to  8 .