JAW FOR A SURGICAL TUBULAR SHAFT INSTRUMENT

Abstract

A jaw assembly for a surgical tubular shaft instrument includes a supporting component, a first arm and a second arm, the first arm and/or the second arm each having one link element. The arms are held by the supporting component in the axial direction. A cam carrier element is axially movable relative to the supporting component and carries at least two cams. Each link element is designed to be in contact with at least two cams when there is a relative axial movement between the supporting component and the cam carrier element, the cams being provided on the cam carrier element. Each link element is further designed to slide off of the cams to effect an opening or closing of the jaw assembly.

Claims

1. A jaw assembly for a surgical tubular shaft instrument, the jaw assembly comprising: a supporting component, a first arm including a first active area, and a second arm having a second active area, each of the first arm and/or the second arm having one link element and the arms being held by the supporting component in the axial direction, the jaw assembly further comprising a cam carrier element which is axially movable relative to the supporting component and carries at least two cams, each link element designed to be in contact with at least two cams when there is a relative axial movement between the supporting component and the cam carrier element, said cams being provided on the cam carrier element, each link designed to slide off said cams to effect an opening or closing of the jaw assembly by a movement of the first arm and the second arm directed toward each other or away from each other.

2. The jaw assembly for a surgical tubular shaft instrument according to claim 1, wherein the supporting component is formed integrally with a shaft component of the shaft or is fastened thereto and the cam carrier element is a slide which is axially movable relative to the shaft.

3. The jaw assembly for a surgical tubular shaft instrument according to claim 1, wherein the first arm and the second arm are elastically coupled.

4. The jaw assembly for a tubular shaft instrument according to claim 1, wherein at least two link paths are formed on at least one link element.

5. The jaw assembly for a surgical tubular shaft instrument according to claim 1, wherein the first arm and/or the second arm has/have at least one projection which engages in an area of the supporting component and in this way restricts or prevents an axial movement of the arm relative to the supporting component.

6. The jaw assembly for a surgical tubular shaft instrument according to claim 5, wherein the at least one projection is provided on a resiliently flexible extension of the pertaining link element of the arm and the resiliently flexible extension urges the projection toward the supporting component and in this way secures engagement of the at least one projection in the supporting component, with the flexibility of the extension being preferably adjusted so that the mobility and the movements of the link element and of the active area substantially are not influenced by the extension.

7. The jaw assembly for a surgical tubular shaft instrument according to claim 1, wherein at least one link element is planar and the cam carrier element is planar and the at least one link element is adjacent to a flat side of the cam carrier element so that a sandwich-type structure is formed.

8. The jaw assembly for a surgical tubular shaft instrument according to claim 7, wherein the cam carrier element and at least one link element form at least one area in which a link path and the pertaining cam of the cam carrier element form an undercut so that the link element is prevented from lifting off the cam carrier element, wherein at least one area of an undercut is provided over the entire range of movement of the link element to the cam carrier element from a completely opened position to a completely closed position of the jaw.

9. The jaw assembly for a surgical tubular shaft instrument according to claim 1, wherein the surgical instrument is a surgical clip applier and the arms of the jaw are adapted to hold and apply a surgical clip by closing the jaw, wherein the surgical clip is a double-webbed clip which includes two clip halves being connected to each other at their two distal ends only.

10. The jaw assembly for a surgical tubular shaft instrument according to claim 9, wherein the active areas of the two arms of the jaw are designed to be displaced in the completely opened position of the jaw by a clip arranged in the jaw outwardly beyond the lateral position of the active areas of the arms adopted by the active areas in the completely opened position of the jaw when no clip is arranged in the jaw.

11. The jaw assembly for a surgical tubular shaft instrument according to claim 1, wherein at least three link paths are configured on at least one link element, wherein at any given time during the opening and closing operation of the jaw, at least two link paths each are adjacent to one cam provided on the cam carrier.

12. The jaw assembly for a surgical tubular shaft instrument according to claim 11, wherein the jaw includes an exchangeably mountable clip reservoir in which a plurality of clips are provided, the clip reservoir being arranged at least partly in a plane that is in parallel to the sandwich-type structure of the at least one link element and the cam carrier element, wherein the clips can be supplied at least partly in the clip reservoir past the sandwich-type layered structure to the distal areas of the arms.

13. The jaw assembly for a tubular shaft instrument according to claim 1, wherein the active areas of the first arm and the second arm exhibit a kinematics curve symmetrical to a central axis of the jaw.

14. The jaw assembly for a surgical tubular shaft instrument according to claim 1, wherein the surgical instrument is a pair of scissors, a needle holder, a clamp or any other surgical instrument in which two arms are movable toward each other and/or past each other.

15. The jaw assembly for a surgical tubular shaft instrument according to claim 1, wherein the jaw assembly is of a design exhibiting no swivel axis.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0033] Further advantages and features of the invention are evident to those skilled in the art from the enclosed figures and the detailed description of the embodiments.

[0034] FIGS. 1A-1F show a jaw according to a first embodiment of the present invention;

[0035] FIGS. 2A-2F show a first arm of the jaw according to FIG. 1;

[0036] FIGS. 3A-3F show a second arm of the jaw according to FIG. 1;

[0037] FIGS. 4A-4F show a cam carrier element of the jaw according to FIG. 1;

[0038] FIGS. 5A-5F show a jaw according to FIG. 1 in a shaft component of an instrument, with the upper half of the shaft component being cut clear;

[0039] FIGS. 6A-6E show a simplified representation of the first arm and of the cam carrier element according to FIG. 1 in the course of a closing operation;

[0040] FIGS. 7A and 7B show a detailed top view of the jaw of FIG. 1, with FIG. 7A illustrating an opened state of the jaw and FIG. 7B illustrating a closed state of the jaw; and

[0041] FIGS. 8A and 8B show a perspective view of the jaw of FIG. 1, with FIG. 8A illustrating an opened state of the jaw and FIG. 8B illustrating a closed state of the jaw.

DETAILED DESCRIPTION

[0042] A first embodiment of the present invention is described hereinafter in detail with reference to FIGS. 1A-5F. Each of the FIGS. 1A-5F show in the figure part A an isometric view of the subject matter, in the figure part B a view from the distal end, in the figure part C a top view, in the figure part D a front view, in the figure part E a bottom view and in the figure part F a rear view related to the isometric view.

[0043] The first embodiment of the present invention relates to a surgical clip applier and, more exactly speaking, to a surgical clip applicator for double-webbed clips of the multi-fire type (so called multi-fire clip applier). A multi-fire clip applier includes a magazine in which clips are stored and from which after application of the clip provided in the jaw a clip is fed to the latter by means of a feeding mechanism into the jaw and, more exactly, into the active area of the jaw. In contrast to this, a clip applier of the single-fire type (so called single-fire clip applier) includes neither a feeding mechanism nor a magazine. In that case, each clip has to be manually introduced individually into the active area of the jaw of the clip applier. The magazine is mounted to be exchangeable on the shaft of the clip applier. The double-webbed clips used in the embodiment are so called ring clips, i.e. double-webbed clips formed of a ring which is punched out of a metal sheet.

[0044] A multi-fire double-webbed clip applier jaw 1 according to this embodiment comprises a supporting component 10. The supporting component 10 in this embodiment is formed by a shaft tube 10 only the lower half of which is shown in FIGS. 5A-5F. The shaft tube 10 is detachably connectable at its proximal end to a handle of the clip applier. The supporting component 10 may also be constituted by another component, however, which is adapted to be arranged on a shaft or shaft component of an applier shaft. In this case the supporting component 10 can be indirectly arranged on a handle of the applier. Slits 12, 13 are provided at the distal end 11 of the shaft tube 10 from which the active areas 110, 210 of arms 100, 200 are projecting. In addition, two recesses 14 and 15 each are provided on both sides in the shaft tube 10.

[0045] Each of the first arm 100 as shown in FIGS. 2A-2F and the second arm 200 as shown in FIGS. 3A-3F has an active area 110, 210 as well as a flatly formed link element 120, 220 and a resiliency elastic extension 130, 230, as already illustrated before. The active area 110, 210 of each arm 100, 200 includes a channel 111,211 in which a surgical clip can be fed from a magazine (not shown) by means of a feeding mechanism (equally not shown) into the active area 110, 210 of the arms 100, 200. A stop 112, 212 is provided to prevent the clip from falling out of the active area 110, 210 of the jaw 1 to the fore (distally). Said stop 112, 212 is adapted to the shape of the distal area of the clip so that the clip is substantially adjacent along its entire distal area to the stop 112, 212 and along a lateral border strip 113, 213 of the channel 111, 211 to the arms 100, 200. The elastic extension 130, 230 extends from the link element 120, 220 of each arm 100, 200 in the proximal direction.

[0046] The elastic extension 130, 230 is designed to be resilient especially in its distal area, i.e. where it is connected to the link element 120, 220. In this embodiment an elasticity resulting in a significant lengthening of the extension 130, 230 is not desired. At the proximal end of each elastic extension 130, 230 two projections 131, 132 and, resp., 231, 232 are provided which project from the respective elastic extension 130, 230 in the radial direction. Said projections 131, 132 and, resp., 231, 232 are dimensioned so that they fit into the recesses 14, 15 formed in the shaft tube 10. The elastic extensions 130, 230 are moreover designed so that the proximal ends thereof are urged against the inner wall of the shaft tube by the shape and elasticity of the extensions so that the projections 131, 132 and, resp., 231, 232 are safely accommodated in the recesses 14, 15. For this purpose, the elastic extensions are designed so that the proximal ends thereof extend to be slightly outwardly bent. The elasticity of the extensions is dimensioned so that sufficient urging force is prevailing outwardly in the radial direction to secure the projections 131, 132 and, resp., 231, 232 in the recesses 14, 15, but at the same time the movement of the link elements 120, 220 and of the active areas 110, 210 is not substantially impaired or impeded.

[0047] The arms 100, 200 are held to be substantially immobile vis-à-vis the shaft component 10 in the axial direction by the projections 131, 132 and, resp., 231, 232 that engage in the recesses 14, 15 in the shaft component 10.

[0048] A cam carrier element 300 as illustrated in FIGS. 4A-4F, which will be referred to as slide in the following, is arranged between the two link elements 120, 220 of the two arms 100, 200. The slide 300 is provided with a fastening strap 310 at its proximal end. Said fastening strap 310 may be inserted in a distal end of a push rod (not shown) and in this way may be permanently fastened to the same. This assembly is especially advantageous for single-use instruments such as the present clip applier. The present clip applier is referred to as single-use instrument despite an exchangeable clip magazine, because it cannot be cleaned and sterilized. For sufficient cleaning the clip applier and hence also the jaw would have to be dismountable, which is not the case with the described connection between the slide 300 and the push rod. Alternatively the push rod may be provided with a fastening strap and the slide may be provided with a corresponding seat or recess. A releasable fastening is possible as well, but it is not provided in this embodiment. With a releasable connection between the slide 300 and the push rod the instrument can also be configured as a reusable instrument.

[0049] The push rod can be shifted into the distal direction vis-à-vis the shaft tube by means of an actuating lever or the like provided on a handle (e.g. pneumatic or hydraulic drive). Subsequently, the push rod can be withdrawn into its home position. This reciprocal movement of the push rod relative to the shaft tube 10 causes an opening and closing operation of the jaw.

[0050] The cam carrier element or the slide 300 includes on its upper side shown in FIG. 4C three cams 321, 322, 323 and on its lower side shown in FIG. 4E three cams 331, 332, 333. In addition, the slide includes on its upper side a recess 325 and on its lower side a recess 335 which are partly overlapping and thus define a passage in the slide 300.

[0051] The upper arm 200 comprises three link paths 221, 222, 223 at its link element 220. At the elastic extension 230 of the upper arm 200 a projection or thickened area 225 is formed substantially opposite to the projections 231, 232. Similarly, three link paths 121, 122, 123 are formed at the link element 120 of the lower arm 100. The elastic extension 130 of the lower arm 100 moreover also includes a projection or thickened area 125 which is configured at the elastic extension 130 to be substantially radially facing away from the projections 131, 132. The two arms 100, 200 and especially the link elements 120, 220 thereof form a sandwich structure with the slide 300.

[0052] The cams 321, 322, 323 of the slide 300 are adjacent in the given order to the link paths 221, 222, 223 of the upper arm 200 and during an opening or closing operation slide along the same. It is referred to the fact that not every cam will be in contact with the corresponding link path at any given time of an opening or closing operation. A cam may happen to move away from the link path over a certain range of an opening or closing operation and a gap may happen to be formed between the cam and the pertaining link path. This behavior will be explained in greater detail in the following. It is merely shown here which cam is assigned to which link path. This is also applicable, as a matter of course, to the link paths 121, 122, 123 of the lower arm 100 and the pertaining cams 331, 332, 333 of the slide 300.

[0053] Referring to FIGS. 6A-6E, hereinafter an assembly of the jaw 1 as well as an opening and closing operation of the jaw 1 will be described using the example of the upper arm 200. FIGS. 6A-6E illustrate top views of the slide 300 and the upper arm 200, wherein part of the upper arm 200 is cut clear so that the link paths 221, 222, 223 are evident also in the top view. The lower arm 100 behaves corresponding to the upper arm, even though the two arms are not identical, as the lower arm 100 is rounded on its lower side so that it will find its place in the shaft tube 10. The lower arm 100 therefore has been omitted for better understanding of the kinematics of the system in FIGS. 6A-6E. FIG. 6A illustrates the mounting position of the upper arm 200 at the slide 300, i.e. this position of the upper arm 200 and the slide 300 relative to each other cannot be adopted any more once the jaw has been mounted to an instrument shaft and accordingly the slide 300 has been mounted with its fastening strap 310 to a push rod. In the mounting position especially the link path 223 is arranged distally from the cam 323 so that the upper arm 200 in the position shown in FIG. 6A can be rotated anti-clockwise and thus can be removed from the slide 300.

[0054] Since in this embodiment the cams 231, 322, 323 of the slide 300 and the link paths 221, 222, 223 of the upper arm form an undercut so that the upper arm cannot lift off the slide 300 even if no retaining clamp is provided, the upper arm 200 cannot be simply attached to the slide 300. Therefore it is important that the upper arm 200 can be rotated in the mounting position relative to the slide 300, as only in this way it is possible to mount the upper arm 200 on the slide 300. The upper arm 200 hence is inclined when being attached to the slide 300 and then is rotated clockwise until the link path 221 gets into contact with the cam 321 and the link path 222 gets into contact with the cam 322. The link paths 221, 222 form undercuts with the cams 321, 322. The lower arm 100 is mounted to the slide 300 based on the same principle. Accordingly, the link paths 121, 122 get into contact with the cams 331, 332 and equally form undercuts.

[0055] The two arms 100, 200 and the slide 300 are then inserted from the front side into a shaft tube 10 of an instrument shaft in which a push rod including a recess matching the fastening strap 310 is arranged. In order to allow the arms 100, 200 to be inserted with the slide 300 into the shaft tube 10 the projections 131, 132 and 231, 232 have to be pressed inwardly. To enable this, the two recesses 325, 335 are formed in the slide 300. In the mounting position the thickened portions 125, 225 of the two arms 100, 200 are arranged so that they are located in the axial direction exactly next to the recesses 325, 335. The elastic extensions 130, 230 of the two arms 100, 200 thus may be elastically deformed inwardly so that the thickened portions 125, 225 immerse into the recesses 325, 335. In this way the projections 131, 132 and 231, 232 each provided on the outside are shifted toward the inside so far that the arms 100, 200 can be inserted into the distal end of the shaft tube 10. During insertion the elastic extensions 130, 230 are urging radially outwardly.

[0056] When the arms 100, 200 and the slide 300 are progressively inserted into the shaft tube 10, the fastening strap 310 then establishes a connection to a corresponding seat on the push rod in the shaft tube. In this way the slide 300 is permanently connected to the push rod. From this time the slide 300 substantially cannot be pushed any further in the proximal direction into the shaft tube 10. When the arms 100, 200 are continued being pushed into the shaft tube, the arms are displaced also vis-à-vis the slide 300. In this way a contact is made between the cam 323 and the link path 223 of the upper arm 200 and a contact is made between the cam 333 and the link path 123 of the lower arm. In this position the two arms 100, 200 are not rotatable against the slide 300, even if no shaft tube 10 were provided. At the same time, the two thickened portions 125, 225 of the two arms 100, 200 are displaced vis-à-vis the recesses 325, 335 of the slide so that the elastic extensions 130, 230 are urged further outwardly. The two arms 100, 200 may be somewhat further pushed into the shaft tube 10, until the projections 131, 132 are opposed to the recesses 14 and the projections 231, 232 are opposed to the recesses 15. In this position, due to the elasticity of the two extensions 130, 230, the projections 131, 132, 231, 232 immerse substantially simultaneously into the recesses 14, 15 in the shaft tube 10 and thus secure the two arms 100, 200 in the axial direction.

[0057] In this embodiment the distance of the two projections 131, 132 is slightly smaller than the distance of the two recesses 14. In this way, when tensile force is applied to the lower arm 100, i.e. when the lower arm 100 is pulled in the distal direction, the tensile force is first transmitted from the projection 131 to the distal wall of the proximal recess 14, thus generating a moment in the extension 130 which additionally urges the projection 132 toward the inner wall of the shaft tube 10. Hence the connection between the lower arm 100 and the shaft tube 10 is further secured. The same principle is also applied to the upper arm 200 so that in this case, too, a tensile force is transmitted first from the projection 231 to the distal wall of the proximal recess 15, before the distal wall of the distal recess 15 engages in the distal wall of the projection 232 and in this way equally transmits forces from the upper arm 200 into the shaft tube 10.

[0058] The jaw 1 now is in the home position or zero position shown in FIG. 6B. When the handle of the instrument is actuated, in this embodiment the push rod is pneumatically pushed distally in the shaft tube. Thus also the slide 300 moves in the distal direction. During this movement the cam 321 slides along the link path 221 and shifts the arm 200 and, resp., the active area 210 thereof in FIGS. 6A-6E downwards. The cam 322 slides along the link path 222 and in this way enables the afore-described downward movement of the active area 210. In addition, the cam 323 slides along the link path 223 and stabilizes the position of the arm 200 relative to the slide 300. Since the front part of the arm 200 is laterally displaced while the rear part of the arm is received in the shaft tube 10, it is crucial that the elastic extension 230 of the upper arm has such elasticity that the displacement of the active area 210 is not prevented or significantly impaired by the elastic extension 230. The jaw 1 thus adopts the position shown in FIG. 6C.

[0059] With a further progressing closing operation of the jaw 1 the cams 321, 322 continue sliding along the link paths 221, 222, while the cam 323 slightly lifts off or moves away from the link path 223. The shape of the cams 321, 322 and of the link paths 221, 222 is configured so that at the beginning of the closing operation the active area 210 moves inwardly relatively quickly, whereas toward the end of the closing operation the active area 210 moves inwardly more slowly. In this way at the beginning of the closing operation a relatively far distance can be covered relatively quickly, whereas toward the end of the closing operation, when the clip has to be pressed in the jaw 1, a short distance is covered, wherein a great force may be applied to the clip, however. It is not disturbing in this context that at the beginning of the closing operation only a relatively low force can be applied. A position of the upper arm 200 and of the slide 300 during this phase of the closing operation is illustrated in FIG. 6D.

[0060] At the end of the closing operation the upper arm 200 and the slide 300 reach the position illustrated in FIG. 6E. In this position the cam 321 and the link path 221 form a maximum contact surface so that in this position also the maximum force can be exerted by the cam 321 on the link path 221 so as to ensure pressing the clip in the active area 210.

[0061] During an opening operation the upper arm 200 and the slide 300 pass the positions shown in FIGS. 6A-6E in the reverse order, wherein for example in the position shown in FIG. 6C the cam 323 again contacts the link path 232 and in this way necessarily displaces the active area 210 upwards, i.e. opens the jaw 1 in a forced and guided manner. The opening operation thus is not dependent on an elasticity of an arm or an elastic connection of the two arms in this embodiment. Inter alia, this offers the advantage that the jaw 1 cannot be closed inadvertently e.g. while being introduced to a trocar, for example in that an active area of an arm 100, 200 is pressed against the inner wall of the trocar and then evades radially inwardly to the active area of the other arm. Should this happen, the clip provided in the jaw is pressed and when the jaw 1 widens into the home position again upon leaving the trocar, the clip falls out of the jaw. In the present case, the active area of the arms 100, 200 cannot be inwardly displaced when pressure from outside is applied to the outer sides of the active areas 110, 210, as the cam 323 and, resp., 333 is adjacent to the link path 123 and, resp., 223 and absorbs this force.

[0062] The lower arm 100 which is not shown and described here substantially passes the same positions and is subjected to comparable influences by the slide 300. In this embodiment the link paths 121, 122, 123, 221, 222, 223 and the cams 321, 322, 323, 331, 332, 333 are configured so that the two active areas 110, 210 of the two arms 100, 200 move symmetrically to the central axis of the jaw 1.

[0063] Moreover this embodiment can be modified so that the jaw 1 initially widens during the closing operation, i.e. initially the two active areas 110, 210 move slightly apart from each other.

[0064] Cooperating with an elastic clip which has been introduced in a slightly compressed manner into the jaw 1 and between the active areas 110, 210, in this way an opening of the clip or opening of the jaw can be obtained which cannot be obtained by other instruments having the same shaft diameter. In order to obtain a temporary widening of the jaw 1 in the position shown in FIG. 6C the link path 223 of the upper arm 200 can be displaced upwardly in the contact area with the cam 323 and the link path 221 can be displaced downwardly in the contact area with the cam 321. In such embodiment, the jaw 1 may not widen farther than the clip can follow due to its elasticity, however, as otherwise the clip may fall out of the jaw 1.

[0065] In a view corresponding to FIG. 5A, the clip reservoir and, resp., the clip magazine of this embodiment is arranged above the sandwich-type structure of the two link elements 120, 220 of the two arms 100, 200 and of the slide 300. The individual clips are advanced individually to the active areas 110, 210 of the jaw 1 by means of an advance mechanism not described in detail here, when a clip provided in the jaw 1 before was applied.

[0066] The jaw 1 of this embodiment includes several special features. A first special feature will be described in detail hereinafter with reference to FIGS. 7A and 7B. In the transitional area 101, 201 between the link element 120, 220 and the active area 110, 210 of each arm 100, 200 each arm is varied from a component planar in the horizontal plane into a component planar substantially in the vertical plane. In order to enable this transitional area 101, 201 to transmit the forces required for pressing a clip, for example, it has to exhibit a particular width in the horizontal lateral direction. Since the arms 100, 200 are sandwiched, however, a shearing effect occurs between the two transitional areas 101, 201, i.e. the distal edges or margins 102, 202 of the transitional area are sliding along each other during a closing operation of the jaw 1. Tissue which happens to get between the two distal edges 102, 202 of the two transitional areas, may thus be inadvertently damaged or even severed. By this effect a vessel to which a clip is intended to be applied may be perforated, which constitutes a high risk to the patient. In order to avert such risk, the transitional areas 101, 201 are configured so that the point at which the two distal edges 201, 202 are superimposed when the jaw 1 is completely closed, is located in the axial direction of the jaw 1 not distally from the proximal end of the clip retained and pressed in the jaw 1.

[0067] This means that this point is provided in the axial direction level with the clip root or proximally therefrom. When the jaw 1 is opened, the clip root of the clip which is not yet pressed thus is still located ahead of this point. When now tissue G, for example a vessel, is introduced into the jaw 1, it gets preferably into contact with the inner side of the clip root of the clip. In this way the clip prevents the tissue G from being introduced further proximally into the jaw 1. During the closing operation the clip root is somewhat displaced in the proximal direction but never beyond the afore-described point. This ensures that the tissue G will never be damaged by the shearing effect of the two sandwiched link elements 120, 220 and, resp., the transitional area 101, 201 of the arms 100, 200. In FIG. 7B a tissue G is shown which is provided in a closed jaw 1. For the sake of clarity, the clip itself is not shown in FIGS. 7A and 7B. However, it is evident from FIG. 7B that the clip restricts penetration of the tissue G into the jaw 1 and thus protects the tissue G. Under safety aspects, hence this point shall be most proximal in the jaw 1. The farther this point is displaced in the proximal direction, however, the more difficult it is to transmit the required moments to the active areas 110, 210 so as to completely press the clip. Therefore the point is placed in the axial direction exactly level with the clip root in the completely closed state of the jaw. This position of the point entails maximum safety with the lowest possible moments by the active areas 110, 210.

[0068] Another special feature of the jaw 1 of the present embodiment is described in detail hereinafter with reference to FIGS. 8A and 8B. This special feature serves for restricting or preventing inadvertent twisting of the two active areas 110, 210 against each other. As is illustrated in FIGS. 8A and 8B, the clip is arranged in the jaw 1 offside a plane in which the force is introduced from the link elements 120, 220 into the active areas 110, 210. Twisting of the active areas 110, 210 against each other, i.e. torsion of each active area outwardly relative to the pertaining link element, results in the fact that an angle is formed between the active areas 110, 210. This would strongly affect the quality of pinching off a vessel by the applied clip. Then the upper webs of a clip in FIGS. 8A and 8B possibly would not be completely pressed against each other and the clip would not sufficiently close the vessel.

[0069] Therefore the transitional area 201 of the upper arm 200 has an area 203 facing the transitional area 101 of the lower arm 100. The transitional area 101 of the lower branch 100 includes an indentation 103 which is laterally opposed to the area 203. During the closing operation of the jaw 1 the area 203 immerses into said indentation 103. At the beginning of the closing operation the forces applied by the active areas 110, 210 are relatively small so that no significant twisting of the active areas 110, 210 takes place. At the beginning of the closing operation of the jaw 1 the area 203 is still outside the indentation 103. However, with a progressing closing operation the area 203 enters into the indentation 103 and the shape of the area 203 adapted to the indentation 103 prevents the two active areas 110, 210 from twisting against each other about their respective longitudinal axis. Especially toward the end of the closing operation, when the forces introduced to the active areas 110, 210 are maximal and the arms 100, 200 most strongly tend to twist against each other, the connection of the area 203 and the indentation 103 counteracts this fact.