SURGICAL INSTRUMENTS

Description

Technical area

[0001] The present disclosure relates to a medical high-frequency surgical instrument (HF instrument), in particular a bipolar vessel sealing instrument, having a jaw part and at least one metal electrode for sealing tissue. Background of the Revelation

[0002] In high-frequency surgery (also known as HF surgery), a high-frequency alternating current is passed through the human body or a body part to specifically cauterize (coagulate) or cut (electrotomy) tissue through the resulting heat. The damaged tissue is later reabsorbed by the surrounding healthy tissue. A significant advantage over conventional cutting techniques using a scalpel is that bleeding can be stopped simultaneously with the incision by closing the affected vessels, a process known as coagulation.

[0003] Currently, monopolar HF technology is most commonly used in HF surgery. One pole of the HF voltage source is connected to the patient via a counter electrode with the largest possible surface area, for example through contacts on the operating table on which the patient lies, through contact armbands or contact footbands, or through adhesive electrodes. This counter electrode is often called the neutral electrode. The other pole is connected to the surgical instrument, which forms the so-called active electrode. The current flows via the path of least resistance from the active electrode to the neutral electrode. The current density is highest in the immediate vicinity of the active electrode; this is where the thermal effect is most pronounced. The current density decreases with the square of the distance.The neutral electrode should cover as large a surface area as possible and be well connected to the body to keep the current density in the body low and avoid burns. The skin at the neutral electrode is not noticeably heated due to its large surface area. Strict safety precautions apply when applying the neutral electrode. To avoid burns, correct positioning and good contact of the neutral electrode (depending on the surgical area) are crucial.

[0004] With bipolar HF technology, in contrast to monopolar technology, the current flows through a small part of the body—the part where the surgical effect (incision or coagulation) is desired. Two mutually insulated metal electrodes, which are housed in the jaws of the HF instrument and between which the HF voltage is applied, are applied directly to the surgical site. The circuit is closed via the intervening tissue. The thermal effect occurs in the tissue between the metal electrodes.

[0005] In such HF instruments, especially bipolar sealing instruments, the jaws are preferably manufactured / designed in a sandwich construction. The jaws consist of or include the thin metal electrode, which acts as the contact surface with the tissue, a plastic spacer that provides electrical and thermal insulation, and a support component, which is designed and configured to ensure force transmission and contains a closing mechanism. The support component provides the jaws with the necessary stability and rigidity.

[0006] However, such a sandwich-designed jaw part is complex and costly to manufacture. The various components that must be connected together result in cumulative manufacturing tolerances, which reduces the accuracy of fit and thus the quality of the jaw part or the HF instrument.

[0007] One approach to overcome these disadvantages is to design / form the metal electrode or a branch of the jaw part as a solid component.

[0008] However, such a solid metal electrode has a high thermal mass, which, especially with larger jaws, means that a large part of the energy supplied to the metal electrode by an RF generator does not flow into the tissue sealing but into the heating of the solid metal electrode.

[0009] Excessively large cooling mass on the back of the electrodes could therefore draw so much heat energy from the metal electrode and the tissue that the sealing process would take longer than necessary. At the same time, the jaws should have a heat sink that can cool the metal electrode when not in use. This minimizes unintentional damage to surrounding tissue, for example, when touching it during tissue preparation or when changing the position of the jaws.

[0010] US 2020 / 100833 A1 discloses an HF instrument with a jaw part with two legs. The two legs are movable relative to each other between an open and a closed state of the jaw part. The jaw part has at least one metal electrode with a contact surface for contacting tissue. The instrument has a heat sink. The at least one metal electrode and the heat sink are in a thermally conductive connection with each other.

[0011] US 2015 / 196352 A1, US 2021 / 369333 A1, US 2021 / 196336 A1 and EP 1 747 761 A1 each disclose a jaw part with a heat sink for an electrode. Brief description of the revelation

[0012] The object of the present disclosure is therefore to overcome or at least mitigate the disadvantages of the prior art and, in particular, to provide a surgical instrument in which an electrode can be both effectively heated and cooled. In particular, excessive heat losses due to cooling should be avoided.

[0013] This object is achieved by a surgical instrument according to the features of claim 1.

[0014] The present disclosure relates to a surgical (high-frequency) instrument having a jaw part or a distal effector with two legs or arms that are movable relative to one another between an open state / release state and a closed state / clamping state of the jaw part. The jaw part has at least one (metal) electrode with a contact surface for contacting tissue and a heat sink facing away from the contact surface. In the closed state of the jaw part, the at least one metal electrode and the at least one heat sink are spaced apart from one another and thermally separated, and in the open state of the effector, the at least one metal electrode and the at least one heat sink are in a (heat-conducting / heat-transferring / thermally coupled) connection with one another.

[0015] The jaw part can be moved between the open state and the closed state like scissors. The jaw part has, in particular, two arms that can be moved relative to one another and can be opened and closed. In the closed state, the contact surface is in contact with the tissue, and in the open state, the contact surface is spaced from the tissue. The at least one metal electrode and the at least one heat sink are arranged so that they can be moved relative to one another. When the jaw part is closed, a closing or clamping force (of the jaw part) acts on the at least one metal electrode and the at least one heat sink. The closing force causes a relative movement of the at least one metal electrode and the at least one heat sink. The relative movement can (thermally) separate the at least one metal electrode from the at least one heat sink. When the jaw part is opened, the closing force is eliminated.The loss of the closing force, in turn, causes an opposite relative movement or opening movement between the at least one metal electrode and the at least one heat sink. This opening movement connects the at least one metal electrode and the at least one heat sink in such a way that they are thermally coupled or in a thermally conductive connection.

[0016] In other words, a surgical instrument, in particular an HF instrument, is disclosed, comprising: a jaw part with two legs or branches that are movable relative to each other between a tissue-release position and a tissue-clamping position of the jaw part; at least one electrode, which can optionally be supplied with an electric current and is mounted on one leg on a side facing the other leg;and a heat sink which is arranged on a side of the at least one electrode facing away from the other leg, and with a pretensioning device, preferably a spring, which is provided and designed to pretension the at least one electrode against a thermal contact surface of the heat sink for heat transfer and whose pretensioning direction points towards the other leg, so that in the tissue clamping position the at least one electrode is spaced from the thermal contact surface counter to a spring pretension and in the tissue release position the at least one electrode and the thermal contact surface of the heat sink are in heat-conducting contact with one another. ;

[0017] The core of the present disclosure is that at least one metal electrode and at least one heat sink of a surgical instrument can be thermally decoupled from one another (by relative movement) and recoupled. This means that the thermal conductivity between the at least one metal electrode and the at least one heat sink can be varied depending on the operating state of the surgical instrument. Specifically, the at least one heat sink can be connected to and decoupled from the at least one metal electrode.

[0018] The surgical instrument according to the present disclosure has the following advantages. The at least one metal electrode and the at least one heat sink can be thermally decoupled and recoupled depending on the operating state. This means that the at least one heat sink or the cooling mass of the at least one heat sink can be designed to be large enough that the at least one heat sink can effectively cool the at least one metal electrode when the at least one metal electrode is not in use. At the same time, it can be ensured that the large cooling mass of the heat sink does not cool the metal electrode unnecessarily when the metal electrode is to be heated to seal tissue. This allows the metal electrode to seal the tissue effectively. At the same time, the metal electrode can cool down quickly thanks to the large connectable cooling mass when the surgical instrument is not in use.This prevents or at least reduces damage to the surrounding tissue caused by (accidental) contact with the (heated) metal electrode. Furthermore, the jaws are sealed to prevent contamination.

[0019] Advantageous further developments of the present disclosure are the subject of the appended subclaims.

[0020] The instrument can preferably have an elastic element, in particular a spring, which is compressed in the closed state by the closing force of the jaw part. If the closing force is removed / decreased, a spring force of the elastic element can bring about the relative movement of the at least one metal electrode and the at least one heat sink. This means that the at least one heat sink and the at least one metal electrode can be prestressed with at least one elastic element. The at least one elastic element can be compressed in particular when the jaw part is closed. If the force that presses the legs of the jaw part together is removed, the at least one metal electrode and the at least one heat sink can be moved relative to one another by the spring force of the elastic element.This allows the at least one metal electrode and the at least one heat sink to be connected at least partially "automatically" or without further user intervention, and thus thermally coupled, when the jaws are opened. This allows the metal electrode to be effectively cooled when the jaws are opened. The elastic element allows the cooling to be activated without the user having to manually activate it.

[0021] Due to the relative movement of the at least one metal electrode and the at least one heat sink to each other, an air gap can be created between the two components, which causes thermal insulation between the two components.

[0022] The at least one elastic element can preferably be a coil spring. Coil springs are particularly cost-effective components. Preferably, the at least one spring can be arranged such that the spring force acts perpendicular to a longitudinal extension of the individual legs. Specifically, the spring force can therefore act essentially counter to the closing force of the jaw part. The elastic element can also be an elastic cushion, which can preferably be made of an elastic material such as an elastic foam.

[0023] In a preferred embodiment, each leg of the jaw part can have two elastic elements that move a metal electrode relative to a heat sink. Of course, the jaw part can also have one elastic element, three or four, or any number of elastic elements.

[0024] According to an advantageous aspect of the present disclosure, the elastic element can force the at least one metal electrode and the at least one heat sink apart, at least in sections. In the closed state, the elastic element is compressed or prestressed such that, upon transition from the closed state to the open state, the elastic element relaxes, causing the at least one metal electrode and the at least one heat sink to move relative to one another. However, the at least one metal electrode and the at least one heat sink can be configured such that at least sections of the two components abut one another and are thus thermally coupled, despite the relative movement that forces the components apart.Due to the relative movement between the at least one metal electrode and the at least one heat sink, which enables the partial thermal coupling, the at least one heat sink can be connected to the at least one metal electrode and thereby cool the at least one metal electrode.

[0025] Preferably, the at least one metal electrode and the at least one heat sink can be movable relative to each other in a direction of movement that extends perpendicular to a longitudinal extent of the legs. The elastic element can cause the relative movement of the at least one metal electrode and the at least one heat sink. The direction of the relative movement can thus act in the direction of the spring force or in the closing direction.

[0026] According to a further advantageous aspect of the present disclosure, the at least one metal electrode and the at least one heat sink can each have an undercut. The respective undercuts can be spaced apart from one another in the closed state and abut one another in the open state. If the undercuts abut one another, they can form, at least in sections, a support surface between the at least one metal electrode and the at least one heat sink. Thermal energy can be transferred from the at least one metal electrode to the at least one heat sink via the support surface. Thus, the at least one metal electrode and the at least one heat sink can be thermally coupled to one another in the open state, and the at least one heat sink can cool the at least one metal electrode.

[0027] Preferably, the undercut can limit the relative movement between the at least one metal electrode and the at least one heat sink in the direction of movement. Thus, the undercut can prevent the at least one metal electrode and the at least one heat sink from being completely separated or separated by the spring force. Rather, the support surface of the undercut can be used to realize the thermal coupling between the at least one metal electrode and the at least one heat sink. The at least one metal electrode can be cooled by the at least one heat sink via the support surface.

[0028] According to a further advantageous aspect of the present disclosure, the at least one metal electrode can have an electrode body with the contact surface and a first toothing with a number of first teeth. The first teeth can extend, in particular, from the electrode body into a side facing away from the contact surface. The at least one metal electrode can therefore have a base body from which the first teeth extend. The first teeth can extend, in particular, in the direction of the at least one heat sink. This makes it possible to provide a toothing geometry that is prepared to be connected (movably relative to one another) to a corresponding toothing geometry of the at least one heat sink.

[0029] Preferably, the first teeth of the first toothing can each have a first base section, which preferably extends perpendicular to the electrode body, and a first head section, wherein the first head section widens from the first base section in a mushroom shape parallel to the electrode body. This means that the first base section can extend perpendicular to a longitudinal extent of the heat sink or protrude perpendicularly from the heat sink. The first head section can in turn extend perpendicular to the first base section. Thus, the first head section can extend in a longitudinal extent of the legs.

[0030] According to a further advantageous aspect of the present disclosure, the at least one heat sink can have a base body and a second toothing with a number of second teeth. The second teeth can extend from the base body in the direction of the at least one metal electrode. The base body of the at least one heat sink can be an extension of the legs or a connection between the handles and the jaw part. The second teeth can extend perpendicularly from the base body in the direction of the metal electrode. Thus, a toothing geometry can be provided that is prepared to be (movably) connected to the corresponding toothing geometry of the metal electrode.

[0031] Preferably, the second teeth can each have a second base section and a second head section. The second base section can preferably protrude perpendicularly from the base body. The second head section can widen outward from the second base section in a mushroom shape parallel to the base body. The second base section can therefore protrude straight from the base body of the heat sink in the direction of the metal electrode. A longitudinal extension of the second head section can thus extend parallel to the base body of the heat sink or along a longitudinal extension of the legs. The first head sections and the second head sections together form the undercut(s).

[0032] According to a further advantageous aspect of the present disclosure, the first teeth and the second teeth can each alternately mesh with one another. This means that the first teeth of the metal electrode can each be arranged adjacent to the second teeth of the heat sink. Thus, the contact surface between the at least one metal electrode and the at least one heat sink can be enlarged in the open state.

[0033] Preferably, the first teeth and the second teeth can interlock such that the respective mushroom-shaped head sections abut one another in the open state and form the undercut or the multiple (parallel) undercuts. This means that in the open state, the mushroom-shaped head sections can form the common support surface for the thermal coupling. In the closed state, however, the mushroom-shaped head sections can be spaced apart from one another such that the at least one metal electrode and the at least one heat sink are thermally decoupled from one another. The air gap, which provides the thermal insulation, can thus be formed between the mushroom-shaped head sections.

[0034] In other words, the respective legs can have a toothing which is guided in a recess or a corresponding toothing of the other component and forms the undercut.

[0035] According to a further advantageous aspect of the present disclosure, the first head portion of the at least one metal electrode can be arranged behind the second head portion of the at least one heat sink, as viewed from the metal electrode in the direction of movement. Thus, the undercut can be formed between the at least one metal electrode and the at least one heat sink.

[0036] Preferably, the respective head sections can slide along the base sections of the corresponding teeth or be guided by the base sections of the corresponding teeth when the legs move from the open state to the closed state. Thus, the at least one metal electrode and the at least one heat sink can be movable relative to one another.

[0037] According to a further advantageous aspect of the present disclosure, at least one spacer, which is preferably triangular in shape, can be arranged on the at least one metal electrode and / or on the at least one heat sink. The at least one spacer can increase the distance between the at least one metal electrode and the at least one heat sink. Furthermore, this can ensure that no direct contact is established between the at least one metal electrode and the at least one heat sink in the closed state. Thermal energy could be transferred via direct contact, which is undesirable in the closed state. The at least one spacer can also be prism-shaped.

[0038] According to a further advantageous aspect of the present disclosure, the at least one metal electrode can be mounted (movably or pivotably) on a rocker such that the at least one metal electrode is pivoted away from the at least one heat sink when the legs move from the open state to the closed state. This means that the metal electrode can be rotatably mounted / arranged on the rocker and pivoted about a pivot point of the rocker. In the closed state, the metal electrode can be oriented such that the contact surface touches the tissue to be sealed. In the open state, however, the metal electrode can be oriented such that it is cooled by the heat sink. The rocker can thus bring about both an optimal alignment of the contact surface with respect to the tissue and a connectable connection between the metal electrode and the heat sink.

[0039] Preferably, the spring force of the at least one elastic element can press the at least one metal electrode in the open state against the at least one heat sink. The at least one elastic element can be arranged with respect to the rocker in such a way that the at least one elastic element presses the at least one metal electrode against the at least one heat sink. I.e. the at least one elastic element can be arranged on one side of the rocker, wherein the spring force of the elastic element acts on the metal electrode in such a way that the metal electrode is pivoted about the pivot point of the rocker and is pressed or pressed against the heat sink on the other side of the rocker. As a result, in the open state of the jaw part, in which the metal electrode can rotate freely about the rocker, the metal electrode can be in contact with the heat sink and be cooled by it.

[0040] The contact area between the at least one metal electrode and the at least one heat sink can be enlarged by a toothing or a rough (contact) surface in order to enable more efficient heat transfer.

[0041] In the closed state, the elastic element can be compressed by the closing force of the jaw. This means that the spring force can essentially act against the closing force of the jaw.

[0042] The jaw can have either two metal electrodes (bipolar RF technology) or just one (metal) electrode (monopolar RF technology). With monopolar RF technology, the second (recording) electrode can be attached to the patient's body.

[0043] The surgical instrument may, in particular, be an electrosurgical instrument for open surgical procedures. However, the surgical instrument may also be suitable for minimally invasive surgical procedures. Short description of the characters

[0044] Fig. 1 shows a schematic representation of a surgical instrument according to a first embodiment of the present disclosure in an open state; Fig. 2 shows a detailed view of a jaw part of the surgical instrument according to the first embodiment of the present disclosure in the open state; Fig. 3 shows a detailed view of a jaw part of the surgical instrument according to the first embodiment of the present disclosure in a closed state; Fig. 4shows a longitudinal section through a jaw part of the surgical instrument according to a second embodiment of the present disclosure in a closed state; and Fig. 5 shows a longitudinal section through a jaw part of the surgical instrument according to the second embodiment of the present disclosure in an open state. Detailed description of the characters

[0045] Fig. 1 shows a surgical instrument 1 with a jaw part 2 with two legs 4. The two legs 4 are movable relative to each other between an open state or a release state and a closed state or a clamping state of the jaw part 2, wherein the Fig. 1shows the surgical instrument 1 in the open state. The surgical instrument 1 further has two (scissor) handles 6, by means of which a user can move the legs 4. Each leg 4 of the jaw part 2 has a metal electrode 8 with a contact surface 10 for contacting tissue and a heat sink 12, which is arranged on a side facing away from the contact surface 10. The heat sink 12 is connected to the respective handle 6. Each leg 4 has two elastic elements or springs 14, which press the heat sink 12 and the metal electrode 8 apart. In the open state or release state, the individual legs and thus also the individual contact surfaces 10 of the instrument 1 are spaced apart from one another. This means that the two contact surfaces 10 do not lie against one another.

[0046] Fig. 2shows a detailed view of one of the legs 4 of the open jaw part 2. The springs 14 are each extended in a relaxed basic position. The metal electrodes 8 each have an electrode body 16 with the contact surface 10 and a first toothing 18. The first toothing 18 has a number of first teeth 20 that extend from the electrode body 16 to the side facing away from the contact surface 10. The teeth 20 each have a first base section 22 and a first head section 24. The first base section 22 extends perpendicular to the electrode body 16, and the first head section 24 widens outward from the first base section 22 in a mushroom shape. This means that the first head section 24 extends at least partially parallel to the electrode body 16.

[0047] The heat sinks 12 each have a base body 26 and a second toothing 28 with a number of second teeth 30. The second teeth 30 extend from the base body 26 in the direction toward the at least one metal electrode 8. That is, the second teeth 30 extend from the base body 26 to the at least one metal electrode 8. The second teeth 30 each have a second base section 32, which preferably extends perpendicular to the base body 26. Furthermore, the second teeth 30 have a second head section 34, which widens outward in a mushroom shape from the second base section 32. That is, the second head section 34 extends at least partially parallel to the base body 26.

[0048] The first teeth 20 of the metal electrode 8 and the second teeth 30 of the heat sink 12 are each arranged (alternating) next to one another and engage with one another. The respective toothings 18, 28 of the metal electrode 8 and the heat sink 12 are arranged such that the metal electrode 8 and the heat sink 12 are movable relative to one another. The metal electrode 8 and the heat sink 12 are preferably movable relative to one another in a direction of movement perpendicular to the longitudinal extent of the legs 4. During the relative movement, the first mushroom-shaped head section 24 of the metal electrode 8 slides along the second base section 32 of the heat sink 12. Accordingly, the second mushroom-shaped head section 34 slides along the first base section 22. The relative movement is limited by the two head sections 24, 34, which abut one another when the jaw part 2 is open and form the undercut.

[0049] The first mushroom-shaped head section 24 and the second mushroom-shaped head section 34 engage with one another and together form an undercut which limits the relative movement of the at least one metal electrode 8 and the at least one heat sink 12 in the direction of movement. Because the respective head sections 24 and 34 bear against one another, the respective teeth 20 and 30 have a large contact surface with one another. Due to the large contact surface of the teeth 20, 30, thermal energy can be transported from the metal electrode 8 to the heat sink 12. This means that the metal electrode 8 and the heat sink 12 are thermally coupled in the open state. In this state, the heat sink 12 can absorb thermal energy from the metal electrode 8 and thus cool the metal electrode 8. In the open state, thermal energy is therefore withdrawn from the metal electrodes 8 by the corresponding, adjacent heat sinks 12.

[0050] The surgical instrument 1 is, in particular, a high-frequency instrument for sealing tissue. To seal tissue, the two legs 4 of the jaw part 2 are pressed together and closed by a closing or clamping force. In the closed or clamped state, the tissue to be sealed is clamped between the two contact surfaces 10 and a high-frequency current flows through it. This heats the tissue clamped between the two contact surfaces 10. Since water is to evaporate from the tissue for sealing, a surface temperature of (at least) 100°C is required at the contact surfaces 10. A thermal coupling of the metal electrodes 8 to the heat sinks 12 would extract considerable thermal energy from the metal electrodes 8 and prolong the heating of the metal electrodes 8. The sealing process would therefore be inefficient.

[0051] Fig. 3shows a detailed view of one of the legs 4 of the closed jaw part 2. When the jaw part 2 is closed, the two contact surfaces 10 of the respective legs 4 rest on one another and are pressed together by a closing force. The two metal electrodes 8 should be hot so that tissue arranged between the two metal electrodes 8 can be sealed by the introduction of thermal energy. Therefore, the metal electrode 8 and the heat sink 12 should be thermally decoupled in the closed state.

[0052] The closing force of the jaw part compresses the springs 14 and moves the metal electrode 8 towards the heat sink 12. During the closing movement, the mushroom-shaped head sections 24, 34 slide along the base sections 22, 32 of the respectively adjacent teeth 20, 30. In the closed state, the mushroom-shaped head sections 24, 34 no longer rest against one another. This reduces the contact surface between the metal electrode 8 and the heat sink 12. Thus, there is less surface area for heat exchange between the metal electrode 8 and the heat sink 12. This means that an air gap is present between the respective head sections 24, 34 and insulates the metal electrode 8 from the heat sink. The metal electrode 8 can thus heat up without the thermal energy being drawn away by the large (cooling) mass of the heat sink 12.The heat sink 12 further includes two triangular spacers 36 that rest on the metal electrode 8 and increase the distance between the metal electrode 8 and the heat sink 12. One of the spacers 36 is arranged at a distal end portion of the jaw part, and the other of the spacers 36 is arranged at a proximal end portion of the metal electrode 8. The spacers 36 are preferably made of a thermally insulating material, such as ceramic.

[0053] Fig. 4shows the jaw part 2 according to a further embodiment of the present disclosure in the closed or clamped state. The metal electrode 8 is pivotably mounted on a rocker 38. When the jaw part is in the closed or clamped state, the metal electrode 8 lies flat against the other leg 40, which is preferably a neutral electrode. In the clamped state, the spring 14 is compressed by the closing or clamping force of the jaw part 2. The metal electrode 8 has only minimal contact with the heat sink 12. Thus, the metal electrode 8 can be effectively heated to seal tissue. The other leg 40 is pivotable about a hinge 42 and exerts the closing or clamping force on the metal electrode 8.

[0054] Fig. 5shows a jaw part 2 according to the further embodiment in the open or release state. The legs 4 are spaced apart. This means that the leg 40 is pivoted away from the metal electrode 8. This eliminates the closing or clamping force on the metal electrode 8. The spring 14 relaxes into its basic position and the spring force pivots the metal electrode 8 about a pivot point of the rocker 38. The metal electrode 8 is thus pressed against the heat sink 12 by the spring force. The metal electrode 8 can thus be cooled by the heat sink 12 in the open state. A contact surface or bearing surface between the metal electrode 8 and the heat sink 12 can also have a toothing or roughened surface to improve heat transfer.

[0055] Of course, the jaw part 2 of the second embodiment can also have two metal electrodes 8 and thus two heat sinks 12. The jaw part 2 can either have two metal electrodes (bipolar RF technology) or just one electrode (monopolar RF technology). List of reference symbols

[0056] 1 Instrument 2 Jaw 4 Leg 6 Handle 8 Metal electrode 10 Contact surface 12 Heat sink 14 Elastic element / spring 16 Electrode body 18 First toothing 20 First teeth 22 First base section 24 First head section 26 Base body 28 Second toothing 30 Second teeth 32 Second base section 34 Second head section 36 Spacer 38 Rocker 40 Further leg 42 Hinge

Claims

1. A surgical instrument (1), in particular an HF instrument, having a jaw part (2) with two legs (4) which can be moved relative to each other between an open state and a closed state of the jaw part (2), wherein the jaw part (2) has at least one metal electrode (8) with a contact surface (10) for contacting tissue and a heatsink (12) facing away from the contact surface (10), characterized in that in the closed state, the at least one metal electrode (8) and the at least one heatsink (12) are spaced apart from each other and thermally separated, and in the open state, the at least one metal electrode (8) and the at least one heatsink (12) are in a thermally conductive connection with each other.

2. The instrument (1) according to claim 1, further comprising at least one elastic element (14), in particular a spring, which is compressed in the closed state by a closing force of the jaw part (2) and moves the at least one metal electrode (8) and the at least one heatsink (12) relative to each other when the closing force is removed.

3. The instrument (1) according to claim 2, wherein the at least one elastic element (14) pushes the at least one metal electrode (8) and the at least one heatsink (12) apart.

4. The instrument (1) according to one of claims 1 to 3, wherein the at least one metal electrode (8) and the at least one heatsink (12) are movable relative to each other in a direction of movement perpendicular to a longitudinal extension of the leg (4).

5. The instrument (1) according to one of claims 1 to 4, wherein the at least one metal electrode (8) and the at least one heatsink (12) each have at least one undercut, wherein the respective undercuts are spaced apart from each other in the closed state and abut against each other in the open state.

6. The instrument (1) according to claim 5, wherein the undercut limits the relative movement between the at least one metal electrode (8) and the at least one heatsink (12) in the direction of movement.

7. The instrument (1) according to one of claims 1 to 6, wherein the at least one metal electrode (8) comprises an electrode body (16) with the contact surface (10) and a first toothing (18) with a number of first teeth (20) extending from the electrode body (16) into the side facing away from the contact surface (10).

8. The instrument (1) according to claim 7, wherein the first teeth (20) of the first toothing (18) each have a first base portion (22), which preferably extends perpendicular to the electrode body (16), and have a first head portion (24), wherein the first head portion (24) widens from the first base portion (22) in a mushroom shape parallel to the electrode body (16).

9. The instrument (1) according to one of claims 1 to 8, wherein the at least one heatsink (12) comprises a base body (26) and a second toothing (28) with a number of second teeth (30) extending from the base body (26) toward the at least one metal electrode (8).

10. The instrument (1) according to claim 9, wherein the second teeth (30) each comprise a second base portion (32), which preferably extends perpendicular to the base body (26), and have a second head portion (34), wherein the second head portion (34) widens from the second base portion (32) in a mushroom shape parallel to the base body (26).

11. The instrument (1) according to claim 9 or 10, wherein the first teeth (20) and the second teeth (30) each alternately engage with each other.

12. The instrument (1) according to claim 10 or 11, wherein the first teeth (20) and the second teeth (30) interlock in such a way that the respective mushroom-shaped head portions (24, 34) abut against each other in the open state and form the undercut and are spaced apart from each other in the closed state.

13. The instrument (1) according to one of claims 1 to 12, wherein at least one spacer (36), which is preferably triangular in shape, is arranged on the at least one metal electrode (8) and / or on the at least one heatsink (12).

14. The instrument (1) according to one of claims 1 to 4, wherein the at least one metal electrode (8) is mounted on a rocker (38) such that the at least one metal electrode (8) is pivoted away from the at least one heatsink (12) during a movement of the leg (4) from the open state into the closed state.

15. The instrument (1) according to claim 14, wherein a spring force of the elastic element (14) swivels the at least one metal electrode (8) in the open state around the rocker (38) and presses it against the at least one heatsink (12).