Electrosurgical forceps with displaceable cutting unit and restoring mechanism

Abstract

The invention relates to electrosurgical bipolar forceps (10), comprising: a first limb (12) and a second limb (14), which are pivotally mounted on each other by means of a pivot joint (16); a cutting unit (70) which is mounted on the first limb (12) so as to be displaceable between a proximal position and a distal position; and a restoring mechanism (88) for restoring the cutting unit (70) from the distal position in the direction of the proximal position, the restoring mechanism (88) having a restoring element (90), which is movably mounted on the first limb (12) and is operatively connected to the second limb (14) in such a way that the restoring element (90) is moved along the first limb (12) by opening the forceps (10) and applies a restoring force to the cutting unit (70), the restoring force displacing the cutting unit (70) from the distal position in the direction of the proximal position.

Description

[0001] Applicant:

[0002] Aesculap AG

[0003] At Aesculap Square

[0004] 78532 Tuttlingen

[0005] General Power of Attorney: 752190 . 9

[0006] 03920017WO 18.09.2025

[0007] BUR / KUN / MAY

[0008] Title: Electrosurgical forceps with sliding head

[0009] Cutting unit and reset mechanism

[0010] Description

[0011] The disclosure relates to an electrosurgical bipolar forceps for preparing, in particular grasping, cutting and / or sealing, tissue, especially vessels, in surgical applications.

[0012] Such an electrosurgical bipolar forceps typically comprises a first arm and a second arm, which are pivotally mounted relative to each other. The forceps have a clamping arrangement on a distal side of the pivot joint, with a first clamping element forming a first electrode and a second clamping element forming a second electrode. Electrosurgical bipolar forceps are generally known as surgical sealing and / or cutting instruments. For sealing, tissue grasped or clamped between the clamping elements of the arrangement is subjected to high-frequency (HF) alternating current, which flows between the two electrodes and through the grasped tissue. This heats and seals the tissue. For cutting clamped and, in particular, sealed tissue, a movable cutting unit with a cutting edge may be provided.

[0013] The present disclosure is based on the objective of improving the user-friendliness of an electrosurgical bipolar forceps with a movable cutting unit.

[0014] This problem is solved by an electrosurgical bipolar forceps having the features of claim 1.

[0015] The forceps according to the invention comprise a first leg and a second leg, the legs being pivotably mounted relative to each other by a pivot joint. On a distal side of the pivot joint, the forceps have a clamping arrangement. The distal side of the pivot joint is the side facing away from the user when the forceps are used as intended. The clamping arrangement comprises a first clamping element, which forms a first electrode of the forceps, and a second clamping element, which forms a second electrode of the forceps. Tissue can be clamped between the clamping elements of the clamping arrangement, in particular to seal the clamped tissue. Preferably, the first clamping element is part of a distal section of the first leg and the second clamping element is part of a distal section of the second leg. On a proximal side of the pivot joint, the forceps have a

[0016] The handle arrangement is designed for handling the pliers. The proximal side of the swivel joint is the side facing the user when the pliers are used as intended. The handle arrangement is formed by the proximal sections of the handle arms. Preferably, each handle arm has at least one finger opening. This ensures particularly safe handling of the pliers. However, the handle arrangement can also be designed in other ways that allow the user to handle the pliers.

[0017] The pliers according to the invention also comprise a cutting unit with a cutting edge for cutting tissue clamped by the clamping arrangement. The cutting unit is slidably mounted on the first leg, in particular along a sliding axis, between a proximal position and a distal position. The cutting unit is slidable from the proximal position to the distal position, at least when the pliers are closed, and in particular only when the pliers are closed, to perform a cutting operation. A cutting operation is thus carried out by sliding the cutting unit from the proximal position to the distal position. Preferably, the cutting edge of the cutting unit is arranged on a distal end face, i.e., an end face of the cutting unit facing away from the user during intended use of the pliers. Preferably, the sliding axis is oriented perpendicular to the pivot axis of the pivot joint.

[0018] The pliers according to the invention also comprise a reset mechanism for returning the cutting unit from the distal position to the proximal position. The reset mechanism has a reset element that is displaceably arranged on the first leg and operatively connected to the second leg in such a way that the reset element is displaced along the first leg when the pliers are opened, and the cutting unit is subjected to a reset force that moves the cutting unit from the distal position to the proximal position. The cutting unit can therefore be moved or reset from the distal position to the proximal position simply by opening the pliers. The cutting unit can be operatively connected to the reset element directly or indirectly, i.e., via at least one further element.The inventors recognized that the claimed return mechanism ensures a particularly reliable return of the cutting unit. During use of the forceps, the guide in which the cutting unit is mounted can become dirty, for example, due to prepared and / or surrounding tissue. The functional connection between the cutting unit and the second arm, i.e., the return mechanism and the return element, provides sufficient return force to reliably move the cutting unit from the distal position towards the proximal position. Because the cutting unit is pushed back when the closed forceps are opened, it is also reliably prevented that the cutting unit remains in the distal position when the forceps are opened.

[0019] Preferably, the return element is operatively connected to the cutting unit in such a way that, at least at the beginning of the opening process, the returning element forces the cutting unit from its distal position towards its proximal position when the closed pliers are opened. Thus, during opening, there is no elastic coupling between the second arm and the cutting unit, but rather a positive coupling. Preferably, the cutting unit is coupled to the return element by means of a positive locking mechanism.

[0020] Preferably, the cutting unit is operatively connected to the return element in such a way that only the return force can be transmitted to the cutting unit via the return element, but not a force acting in the opposite direction to the return force. The cutting unit can then be moved by the return element from the distal position towards the proximal position, but not from the proximal position towards the distal position.

[0021] Preferably, the return element is translationally displaceable along the first leg. This means that the return element can be displaced in a linear motion (translation) along the first leg. Any resulting rotation of the return element during its translational displacement along the first leg preferably has no effect on the cutting unit.

[0022] Preferably, the first leg has an elongated guide structure on which the return element is slidably mounted. In particular, the return element is slidably and rotatably mounted on the guide structure. The elongated guide structure can be an elongated guide groove or a slot.

[0023] In some preferred embodiments, the guide structure has a proximal end, i.e., an end located closer to the user, and a distal end, i.e., an end further away from the user. The proximal and distal ends of the guide structure limit the movement of the reset element along the guide structure in the proximal and distal directions, respectively. Preferably, the guide structure is linear. Consequently, the reset element can be moved linearly along the guide structure. Preferably, the guide structure extends along the longitudinal axis of the first leg or parallel to the longitudinal axis of the first leg. Such a design of the guide structure enables advantageous interaction (direct or indirect) between the reset element and the cutting unit.

[0024] In some preferred embodiments, the guide structure is formed in an integral part of the first leg. The guide structure is therefore not located in a part movably attached to the first leg. In some embodiments, the guide structure is formed in a support structure of the first leg. The support structure can, for example, be formed by a sheet metal stack. In some other embodiments, the guide structure is formed in a handle part of the first leg made of plastic. The guide structure can also be formed jointly by the support structure and the handle part made of plastic.

[0025] In some preferred embodiments, the return element is formed by a connecting rod comprising a first bearing structure, which is slidably and rotatably mounted on the first leg, and a second bearing structure, which is rotatably mounted on the second leg. During opening and closing operations of the pliers, the first bearing structure is displaced along the first leg, particularly within or on an elongated guide structure of the first leg. Furthermore, the first bearing structure is rotated relative to the first leg, and the second bearing structure is rotated relative to the second leg. The return force can be transmitted to the cutting unit by displacing the first bearing structure along the first leg. The connecting rod also has the advantage of stabilizing the pliers against lateral forces.Within the scope of the disclosure, the term "lateral forces" refers to forces that act on the jaws of the pliers parallel to the pivot axis of the swivel joint and radially offset from the pivot axis of the swivel joint. Consequently, lateral forces can cause the jaws of the pliers to twist relative to each other. However, the connecting rod stabilizes the pliers against lateral forces and thus against twisting of the jaws. Preferably, the second bearing structure is arranged immovably on the second jaw and rotatably mounted.

[0026] The return element can also be implemented in other ways. For example, the return element can also be formed by an element of a cable pull arrangement.

[0027] In some preferred embodiments, the pliers are provided with a user-operated drive unit, wherein the drive unit is slidably mounted on the first leg, in particular along a further sliding axis that is aligned parallel to the sliding axis. The cutting unit is coupled to the drive unit in such a way that the cutting unit is moved in the opposite direction when the drive unit is moved. For example, if the drive unit is moved in a proximal direction towards the user, the cutting unit is moved in the opposite distal direction away from the user. The drive unit can increase the user-friendliness of the pliers. Cutting operations are carried out by moving the cutting unit from the proximal position to the distal position, i.e., in the distal direction away from the user.However, for the user, a cutting motion in which the element to be actuated is moved in the proximal direction is generally more intuitive and easier to perform. Preferably, the drive unit has at least one handle structure that projects from the first leg, particularly laterally. This makes it easier for the user to actuate the drive unit.

[0028] In some preferred embodiments, the cutting unit is motion-coupled to the drive unit via a gear mechanism. This provides a mechanically robust motion coupling. However, the motion coupling can also be implemented in other ways, for example, by a cable pull arrangement.

[0029] In some preferred embodiments, the cutting unit is provided to have a rack and pinion thread, and / or the drive unit is provided to have a rack and pinion thread. The rack and pinion thread(s) are part of the aforementioned gear assembly.

[0030] In some preferred embodiments, the gear assembly comprises at least one gear that meshes with the rack thread of the cutting unit and with the rack thread of the drive unit. Such a gear ensures the counter-rotating movement of the cutting unit and the drive unit. Because the gear meshes directly with both rack threads, only a small number of components are necessary to construct the gear assembly. Preferably, the gear is rotatably mounted on the first leg.

[0031] In some preferred embodiments, the cutting unit is operatively connected to the return element via the drive unit, particularly mechanically. Thus, when the pliers are opened, the return force is transmitted from the drive unit to the cutting unit. Preferably, the return element, in particular the connecting rod or its first bearing structure, is directly operatively connected to the drive unit. The return element is therefore in direct contact with the drive unit when transmitting the return force.

[0032] In some preferred embodiments, the cutting unit is only displaceable by the return element to an intermediate position between the proximal and distal positions. In these embodiments, opening the pliers does not move the cutting unit all the way to the proximal position, but the movement to the intermediate position is sufficient to reliably release any blockage of the cutting unit in the guide. The cutting unit can then be moved to the proximal position by other means, for example, by a return spring.

[0033] In some other embodiments, it is provided that the cutting unit can be moved into the proximal position by the return element.

[0034] In some preferred embodiments, it is provided that the

[0035] The return mechanism has a return spring which

[0036] The cutting unit is subjected to a spring force that moves it into the proximal position. The return spring prevents unintentional movement of the cutting unit towards the distal position, as such movement would first require overcoming the spring force of the return spring. If the cutting unit is only moved to the intermediate position by opening the pliers, the return spring also ensures that the cutting unit is returned from the intermediate position to the proximal position. Preferably, the return spring is designed as a helical spring. Preferably, a first end of the return spring is attached to the first leg and a second end of the return spring is attached to the cutting unit, in particular to a blade of the cutting unit.The second end of the return spring can alternatively be attached to the drive unit, whereby the return spring then applies spring force to the cutting unit via the drive unit.

[0037] In some preferred embodiments, the first leg is provided with a sheet metal stack as a support. Preferably, the sheet metal stack has two outer sheets and at least one inner sheet between the outer sheets. Such a sheet metal stack can be manufactured cost-effectively. Preferably, the sheets of the sheet metal stack are attached to one another, in particular welded together. Particularly preferably, at least one section of the cutting unit, in particular the blade of the cutting unit, is slidably mounted between the outer sheets. By mounting it between the outer sheets, the cutting unit is protected from external influences. The inner sheet is preferably recessed in the area of ​​the cutting unit. One or more handle parts made of plastic can be attached to the sheet metal stack. This improves the user-friendliness of the pliers.

[0038] In some embodiments, the second leg has a sheet metal stack as a support. Further advantages will become apparent from the description and the accompanying drawings. Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description. Here, the same reference numerals in different figures denote identical or at least functionally comparable elements. When describing individual figures, reference is also made, where appropriate, to elements from other figures. The following are shown schematically:

[0039] Figure 1 shows a side view of an electrosurgical bipolar forceps with a first arm and a second arm;

[0040] Figure 2 shows a side view of the open pliers with the handle removed;

[0041] Figure 3 shows a side view of the closed pliers with the handle removed;

[0042] Figure 4 shows a side view of the supporting structures of the legs;

[0043] Figure 5 shows an exploded view of the supporting structure of the first leg;

[0044] Figure 6 shows the supporting structure of the first leg with a slidably mounted blade;

[0045] Figure 7 shows a connecting rod of the pliers; and

[0046] Figures 8A-8G show detailed views of the pliers at different times during a cutting process.

[0047] Figure 1 shows a side view of an electrosurgical bipolar forceps 10. The forceps 10 has a first arm 12 and a second arm 14. The arms 12 and 14 are pivotally mounted relative to each other about a pivot axis 18 by a pivot joint 16 (see Figures 2 to 4). The forceps 10 can be opened and closed by pivoting the arms 12 and 14. Figure 2 shows the forceps 10 in their fully open position. Figure 3 shows the forceps 10 in the closed position.

[0048] The forceps 10 have a clamping arrangement 20 on a distal side of the pivot joint 16. The distal side of the pivot joint 16 is the side of the pivot joint 16 that faces away from the user when the forceps 10 are used as intended. The clamping arrangement 20 comprises a first clamping element 22 and a second clamping element 24. By closing the forceps 10, tissue can be clamped between the clamping elements 22 and 24. The first clamping element 22 is formed by a distal section of the first leg 12. The second clamping element 24 is formed by a distal section of the second leg 14.

[0049] The pliers 10 have a handle arrangement 26 on a proximal side of the swivel joint 16 for handling the pliers 10 by a user. The proximal side of the swivel joint 16 is the side of the swivel joint 16 that faces the user when the pliers 10 are used as intended. In this case, the handle arrangement 26 is formed by several handle parts 28 made of plastic. Finger openings 30 can be formed in the handle parts 28.

[0050] Figure 4 shows a side view of the pliers 10 without the handle parts 28. In the present embodiment, the first leg 12 has a sheet metal stack 32 as a supporting structure. Figure 5 shows an exploded view of the sheet metal stack 32. The sheet metal stack 32 has two outer sheets 34 and an inner sheet 36, which is arranged between the outer sheets 34. In the assembled pliers 10, the sheets 34 and 36 are attached to one another, preferably welded together. The plastic handle parts 28 of the first leg 12 are arranged on opposite sides of the sheet metal stack 32 when the pliers 10 are assembled. The handle parts 28 are attached to one another by several press-fit pins 38 (see, for example, Figure 8D). The press-fit pins 38 are inserted through through-holes 40 formed in the sheet metal stack 32.

[0051] In the present embodiment, the second leg 14 also has a sheet metal package 42 as a supporting structure.

[0052] The clamping elements 22 and 24 each form a different electrode of the bipolar forceps 10. The electrodes can be subjected to high-frequency alternating current. If tissue is clamped between the clamping elements 22 and 24, the alternating current flows between the two electrodes and through the clamped tissue. This heats and seals the tissue. In this embodiment, the second leg 14 has an activation switch 66 for activating the alternating current. When the forceps 10 are closed, an activation structure 68 of the first leg 12 is pressed against the activation switch 66. The activation switch 66, and thus the alternating current, is thereby activated. Preferably, the activation switch 66 has a V-shaped notch. This prevents the activation structure 68 from slipping off the activation switch 66.

[0053] In the present embodiment, the pliers 10 have a stabilizing device 44 for stabilizing the pliers 10 against lateral forces. The stabilizing device 44 has a connecting rod 46 which is arranged on the proximal side of the pivot joint 16. Figure 7 shows a perspective view of the connecting rod 46.

[0054] The connecting rod 46 has a first bearing structure 48 and a second bearing structure 50. The first bearing structure 48 is slidably and rotatably mounted on the first leg 12. The second bearing structure 50 is fixedly and rotatably mounted on the second leg 14.

[0055] The first bearing structure 48 has two first bearing pins 52, which project laterally from the connecting rod 46 in opposite directions. The first bearing pins 52 are slidably and rotatably mounted in a respective elongated guide structure 54 of the first leg 12. In this case, the guide structures 54 are formed by elongated holes 56 in the handle parts 28. The second bearing structure 50 has two second bearing pins 58, which project laterally from the connecting rod 46 in opposite directions.

[0056] In this embodiment, the connecting rod 46 is an injection-molded part made of plastic. The first bearing journals 52 and the second bearing journals 58 are monolithically formed with the connecting rod 46.

[0057] The connecting rod 46 stabilizes the clamp 10 against lateral forces. Specifically, a lateral force acting on the first leg 12 can be transferred into the connecting rod 46 via the first bearing structure 48. A lateral force acting on the second leg 14 can be transferred into the connecting rod 46 via the second bearing structure 50. The connecting rod 46 therefore prevents the legs 12 and 14 from twisting relative to each other due to lateral forces.

[0058] The connecting rod 46 is arranged on the first leg 12 and the second leg 14 such that the first bearing structure 48 is pushed away from the pivot joint 16 when the pliers 10 are closed. Thus, when the pliers 10 are closed, the first bearing structure 48 is pushed in a proximal direction towards the user. Conversely, when the pliers 10 are opened, the first bearing structure 48 is pushed away from the user in the opposite distal direction. As mentioned previously, Figure 2 shows the pliers 10 in their open position, i.e., their maximum opening state. When the pliers 10 are open, the first bearing structure 48 rests against a limit stop 60 of the first leg 12 (see, for example, Figure 8A). In this case, the limit stop 60 is formed by one end of the guide structure 54. By placing the first bearing structure 48 against the limit stop 60, further displacement of the first bearing structure 48 in the distal direction is blocked.The connecting rod 46 therefore prevents the pliers 10 from opening beyond the maximum opening state, so that the connecting rod 46 defines the maximum opening state.

[0059] In the present embodiment, the connecting rod 46 has a longer main arm 62 and a shorter secondary arm 64, which is angled relative to the main arm 62. When the clamp 10 is closed (see, for example, Figures 3 and 8C), the main arm 62 rests against the second leg 14 along its longitudinal extent. When the clamp 10 is closed, the secondary arm 64 bridges the gap between the main arm 64 and the guide structure 54.

[0060] In the present case, the second leg 14 has an elongated recess 118 in which the connecting rod 46, in particular the main arm 62, rests when the clamp 10 is closed. The recess 118 is bounded by two opposing side flanks 120, whereby only one of the side flanks 120 is always visible in the sectional views. Preferably, the connecting rod 46, in particular the main arm 62, rests in the recess 118 without play when the clamp 10 is closed.

[0061] The connecting rod 46 has two opposing side flanks 122. When the clamp 10 is closed, each side flank 122 of the connecting rod 46 faces a different side flank 120 of the recess 118. The side flanks 118 thus limit lateral movement of the connecting rod 46. Preferably, the side flanks 122 of the connecting rod 46 are convex. Due to the convex shape of the side flanks 122, the connecting rod 46 is securely guided into the recess 118 when the clamp 10 is closed.

[0062] The forceps 10 also has a cutting unit 70, which is slidably mounted along a sliding axis between a proximal position and a distal position. The cutting unit 70 can cut tissue clamped and, in particular, sealed between the clamping elements 22 and 24.

[0063] The cutting unit 70 has a blade 72 (see Figure 6) with a cutting edge 74. The cutting edge 74 is arranged on a distal end face of the cutting unit 70 or the blade 72. In this embodiment, the blade 72 is slidably mounted between the outer sheets 34 of the sheet metal stack 32. The inner sheet 36 has a recess in the area of ​​the blade 72.

[0064] The cutting unit 70 also has a rack 76 (see, for example, Figure 8A) with a rack thread 78. The function of the rack 76 and the rack thread 78 will be explained in more detail later. The rack 76 can be formed monolithically with the blade 72 or attached to the blade 72.

[0065] The proximal position of the cutting unit 70 (see, for example, Figures 6 and 8A) is the inserted position or starting position of the cutting unit 70. To perform a cutting operation, the cutting unit 70 is pushed from the proximal position into the distal position (see Figure 8C). In the distal position, the cutting edge 74 is located in the area of ​​the clamping arrangement 20 between the clamping elements 22 and 24.

[0066] The pliers 10 also have a user-operated drive unit 80. The drive unit 80 is slidably mounted on the first leg 12 along a further sliding axis, which is aligned parallel to the sliding axis of the cutting unit 70. The cutting unit 70 is coupled to the drive unit 80 in such a way that the cutting unit 70 is moved in the opposite direction when the drive unit 80 is moved. A cutting operation can therefore be carried out by pushing the drive unit 80 in a proximal direction, i.e., towards the user. The cutting unit 70 is then pushed in the opposite distal direction, i.e., away from the user. To facilitate the operation of the drive unit 80, at least one trigger 82 is attached to the drive unit 80, which projects laterally from the first leg 12.

[0067] In this embodiment, the cutting unit 70 is motionally coupled to the drive unit 80 by a gear unit 116. The gear unit 116 is formed by the previously mentioned rack thread 78 of the cutting unit 70, by a rack thread 84 of the drive unit 80, and by a gear 86 that meshes with both the rack thread 78 and the rack thread 84.

[0068] The pliers 10 also have a reset mechanism 88 for resetting the cutting unit 70 from the distal position towards the proximal position. The reset mechanism 88 comprises a reset element 90, which is displaceably arranged on the first leg 12 and is operatively connected to the second leg 14 such that, when the pliers 10 are opened, the reset element 90 is displaced along the first leg 12 and exerts a reset force on the cutting unit 70, which moves the cutting unit 70 from the distal position towards the proximal position.

[0069] In this embodiment, the return element 90 is formed by the connecting rod 46, in particular by its first bearing structure 48. When the cutting unit 70 is in the distal position, the connecting rod 46 exerts the return force on the cutting unit 70 when the pliers 10 are opened.

[0070] In this case, the return element 90, i.e., the connecting rod 46, indirectly applies the return force to the cutting unit 70. Therefore, the return element 90 does not come into direct contact with the cutting unit 70 when it is reset. Instead, the return element 90 transmits the return force to the cutting unit 70 via the drive unit 80. This can be seen, for example, in Figure 8D.

[0071] The return element 90 can also be implemented in other ways. For example, the return element 90 can also be part of a cable pull arrangement.

[0072] Preferably, the return mechanism 88, in addition to the return element 90, has a return spring 93 which applies a spring force to the cutting unit 70, thereby forcing the cutting unit 70 into the proximal position. The return spring 93 can be seen in Figure 6. In this case, a first end of the return spring 93 is attached to a projection 92 of the inner sheet 36 and a second end of the return spring 93 is attached to a projection 94 of the rack 76 (see Figure 6).

[0073] The pliers 10 also have a locking element 96, which is pivotably mounted on the first leg 12 between a locking position and a release position. In this case, the pivot axis of the locking element 96 is parallel to the pivot axis 18 of the pivot joint 16. In the locking position, the locking element 96 prevents the cutting unit 70 from moving from the proximal position towards the distal position. This can be seen, for example, in Figure 8A. In the release position, the cutting unit 70 can move from the proximal position towards the distal position. This can be seen, for example, in Figure 8B. Consequently, cutting operations can be performed when the locking element 96 is in the release position. In this case, the locking element 96 is pivotably mounted on one of the press-fit pins 38.

[0074] To pivot the locking element 96 from the locked position to the release position, the pliers 10 have a release mechanism 98. The release mechanism 98 comprises a release element 100, which is displaceably arranged on the first leg 12 and is operatively connected to the second leg 14 such that the release element 100 is displaced along the first leg 12 by closing the pliers 10 and exerts a release force on the locking element 96, which pivots the locking element 96 from the locked position to the release position.

[0075] In this embodiment, the release element 100 is formed by the connecting rod 46, in particular by its first bearing structure 48. Thus, when the pliers 10 are closed, the connecting rod 46 exerts the release force on the locking element 96, which pivots the locking element 96 from the locked position to the release position.

[0076] The release element 100 can also be implemented in other ways. For example, the release element 100 can also be part of a cable pull arrangement.

[0077] In this embodiment, the pliers 10 comprise an elastically deformable element 102, in this case an elastically deformable spring unit 102, which exerts a spring force on the locking element 96 in the release position, forcing the locking element 96 from the release position into the locked position. If the release element 100, i.e., the connecting rod 46, does not obstruct such a pivoting movement, the spring force causes the locking element 96 to pivot back from the release position into the locked position in order to re-lock the cutting unit 70. In this embodiment, the locking element 96 is a waterjet cutting component made of a metal material. The spring unit 102 is monolithic with the locking element 96. In this embodiment, the spring unit 102 is formed by a meandering extension of the locking element 96.An end section of the spring unit 102 facing away from the locking element 96 is held between two press-fit pins 38.

[0078] When the locking element 96 is in the locked position and the cutting unit 70 is in the proximal position, the locking element 96 and the cutting unit 70 are connected to each other by a permanent locking connection. For this purpose, the locking element 96 has a locking hook 104 which, in the locked position, engages behind a locking projection 106 of the cutting unit 70, thereby forming the locking connection.

[0079] In this case, the locking connection can be formed with the locking element 96 in the locked position by moving the cutting unit 70 into the proximal position. For this purpose, the cutting unit 70 and the locking element 96 each have a contact surface 108 or 110, respectively, oriented obliquely to the sliding axis of the cutting unit 70. When the cutting unit 70 is moved into the proximal position, the contact surfaces 108 and 110 come into contact with each other. The locking element 96 is thereby pivoted in the direction of the release position and thus moves out of the way of the cutting unit 70.

[0080] In this embodiment, the pliers 10 also include a snap disc spring 112, which can be actuated by pivoting the locking element 96 into the release position. When the snap disc spring 112 is actuated, it snaps into place, generating feedback that is audible and / or haptic to the user of the pliers 10. In this embodiment, the locking element 96 has an actuating arm 114 for actuating the snap disc spring 112. The actuating arm 114 can be pressed against the snap disc spring 112 by pivoting the locking element 96 into the release position.

[0081] The function of the pliers 10 is explained again in detail below with reference to figures 8A to 8G.

[0082] Initially, the pliers 10 are in the maximum opening position, in which the first bearing structure 48 rests against the limit stop 60. The cutting unit 70 is in the proximal position and is locked by the locking element 96. This is shown in Figure 8A.

[0083] When the pliers 10 are closed, the first bearing structure 48 is displaced along the guide structure 56 in the proximal direction. Upon sufficient proximal displacement, the connecting rod 46 applies the release force to the locking element 96. This causes the locking element 96 to pivot into the release position by bending the spring unit 102, and the snap disc spring 112 is actuated by the actuating arm 114. This can be seen in Figure 8B.

[0084] The cutting unit 70 is now released and can be moved from the proximal position to the distal position, as shown in Figure 8C. A proximal end of the drive unit 80 is now operatively connected to the first bearing structure 48 of the connecting rod 46. When the pliers 10 are opened from this position, the connecting rod 46 applies a restoring force to the cutting unit 70 via the drive unit 80, pushing the cutting unit 70 from the distal position towards the proximal position. In addition, the locking element 96 is pivoted into the locking position by the spring unit 102. This is shown in Figure 8D. Because the displacement of the first bearing structure 48 is limited by the limit stop 60, the cutting unit 70 is not pushed all the way into the proximal position by the first bearing structure 48.However, the return spring 93 ensures that the cutting unit 70 returns to its proximal position.

[0085] Figure 8E shows how the contact surface 108 of the cutting unit 70 meets the contact surface 110 of the locking element 96. Due to the alignment of the contact surfaces 108 and 110, the locking element 96 is pivoted out of the locked position (see Figure 8F). When the cutting unit 70 is in the proximal position, the locking hook 104 of the locking element 96 engages behind the locking projection of the cutting unit 70 (see Figure 8G). The cutting unit 70 is then locked again.

Claims

Patent claims 1. Electrosurgical bipolar forceps (10) comprising: a first arm (12) and a second arm (14), wherein the arms (12, 14) are pivotably mounted relative to one another by a pivot joint (16), wherein the forceps (10) has on a distal side of the pivot joint (16) a clamping arrangement (20) with a first clamping element (22) forming a first electrode and a second clamping element (24) forming a second electrode, and wherein the forceps (10) has on a proximal side of the pivot joint (16) a handle arrangement (26) for handling the forceps (10) by a user, a cutting unit (70) with a cutting edge (74) for cutting tissue clamped by the clamping arrangement (20), wherein the cutting unit (70) on the first arm (12) is adjustable between a proximal position and a distal position is mounted in a sliding manner,and wherein the cutting unit (70) is displaceable from the proximal position to the distal position for carrying out a cutting operation, at least when the pliers (10) are closed, and a return mechanism (88) for returning the cutting unit (70) from the distal position to the proximal position, wherein the return mechanism (88) has a return element (90) which is displaceably arranged on the first leg (12) and is operatively connected to the second leg (14) in such a way that the return element (90) is displaced along the first leg (12) by opening the pliers (10) and the cutting unit (70) is returned with a return force, acted upon, which moves the cutting unit (70) from the distal position towards the proximal position .

2. Electrosurgical bipolar forceps (10) according to claim 1, characterized in that the resetting element (90) is formed by a connecting rod (46) which has a first bearing structure (48) which is slidably and rotatably mounted on the first leg (12) and a second bearing structure (50) which is rotatably mounted on the second leg (14).

3. Electrosurgical bipolar forceps (10) according to one of the preceding claims, characterized in that the forceps (10) has a user-operated drive unit (80), wherein the drive unit (80) is slidably mounted on the first leg (12), and wherein the cutting unit (70) is coupled to the drive unit (80) in such a way that the cutting unit (70) is moved in the opposite direction when the drive unit (80) is moved.

4. Electrosurgical bipolar forceps (10) according to the preceding claim, characterized in that the cutting unit (70) is coupled to the drive unit (70) by means of a gear unit (116).

5. Electrosurgical bipolar forceps (10) according to the preceding claim, characterized in that the cutting unit (70) has a rack and pinion thread (78), and / or that the drive unit (80) has a rack and pinion thread (84).

6. Electrosurgical bipolar forceps (10) according to the preceding claim, characterized in that the gear unit (116) has at least one gear (86) which is connected to the rack thread (78) of the Cutting unit (70) and combs with the rack thread (84) of the drive unit (80).

7. Electrosurgical bipolar forceps (10) according to one of claims 3 to 6, characterized in that the cutting unit (70) is operatively connected to the return element (90) by the drive unit (80).

8. Electrosurgical bipolar forceps (10) according to one of the preceding claims, characterized in that the cutting unit (70) can only be displaced by the return element (90) to an intermediate position between the proximal position and the distal position.

9. Electrosurgical bipolar forceps (10) according to one of claims 1 to 7, characterized in that the cutting unit (70) can be moved into the proximal position by the return element (90).

10. Electrosurgical bipolar forceps (10) according to one of the preceding claims, characterized in that the reset mechanism (88) has a return spring which applies a spring force to the cutting unit (70) by which the cutting unit (70) is displaced to the proximal position.

11. Electrosurgical bipolar forceps (10) according to one of the preceding claims, characterized in that the first leg (12) has a sheet metal stack (32) as a support, which has two outer sheets (34) and at least one inner sheet (36) between the outer sheets (34), and that at least one section of the cutting unit (70) is slidably mounted between the outer sheets (34).

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