Electrosurgical instruments

Abstract

To provide an improved electrosurgical instrument for thermal cutting of biological tissue. [Solution] The electrosurgical instrument (10) comprises two jaws (15, 16). At least one of the jaws (15) comprises a thermal cutting element (22) having a conductive cutting conductor and a conductive return conductor electrically connected to each other. The cutting element (22) is arranged such that the cutting conductor is not thermally covered at least on the side of one jaw (15) facing the other jaw (16), and the return conductor is surrounded by an insulator (34). The return conductor has lower electrical resistance in the direction of current flow, preferably higher thermal conductivity than the cutting conductor. In this way, during the supply of current to the cutting element (22), a considerably lower amount of heat and temperature is generated in the return conductor than in the cutting conductor, and the return conductor can be used for heat dissipation.

Description

Technical Field

[0001] The present invention relates to an electrosurgical instrument for thermal cutting of biological tissues of human or animal patients and, where appropriate, for achieving further tissue effects.

Background Art

[0002] Electrosurgical instruments having a thermal cutting element are known from the prior art in different embodiments.

[0003] WO 2023 / 187737 discloses a surgical instrument having a thermal cutting device. The thermal cutting device comprises a longitudinal support having a proximal end and a distal end and a cutting blade arranged along its upper surface. Further, the cutting device comprises a dielectric insulator arranged along at least one side surface of the substrate and at least partially extending from the proximal end to the distal end along the substrate. Additionally, the cutting device comprises at least one resistive element adapted for connection to an energy source and arranged in thermal connection with the substrate. Thereby, at least one resistive element is arranged to extend along the dielectric insulator to its distal end section. Further, the cutting device comprises an encapsulating material arranged on the dielectric insulator and on at least one resistive element. The distal end of the substrate comprises a mechanical interface configured to engage with a section of the jaw for attaching the substrate to the jaw.

[0004] Other thermal cutting elements are described in WO 2023 / 187735, US 2023 / 0363812 A1, WO 2023 / 187736, US 2023 / 0310063 A1, EP 3861950 A1, EP 3769709 B1, US 2022 / 0378494 A1 and US 2023 / 0285064 A1.

[0005] U.S. Patent Application Publication No. 2023 / 240740 describes a thermal cutting element in which a heating element is applied to an electrically insulating support. The heating element may have a cross-sectional area that varies along its length. In addition, the heating element comprises different sections that can be configured, for example, linearly or meanderingly, to create a desired temperature profile.

[0006] A method for manufacturing a thermal cutting element for surgical instruments is described in European Patent No. 4076239. In this method, a coating is applied to at least one section of a support by plasma electrolytic oxidation. A heating element is then applied to this coating. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2023 / 187737 [Patent Document 2] International Publication No. 2023 / 187735 [Patent Document 3] U.S. Patent Application Publication No. 2023 / 0363812 [Patent Document 4] International Publication No. 2023 / 187736 [Patent Document 5] U.S. Patent Application Publication No. 2023 / 0310063 [Patent Document 6] European Patent Application Publication No. 3861950 [Patent Document 7] European Patent No. 3769709 [Patent Document 8] U.S. Patent Application Publication No. 2022 / 0378494 [Patent Document 9] U.S. Patent Application Publication No. 2023 / 0285064 [Patent Document 10] U.S. Patent Application Publication No. 2023 / 240740 Specification [Patent Document 11] European Patent No. 4076239 [Overview of the project] [Problems that the invention aims to solve]

[0008] All heating elements found in conventional technology include a support material with relatively high thermal conductivity, which can result in the entire jaw portion heating up, even in undesirable locations such as the outside of the jaw. This can make surgery more difficult for surgeons, especially during longer surgical procedures, as the jaw portion of the instrument may thermally adhere to the patient's tissue in undesirable locations within the surgical field, potentially causing unintended tissue damage and thus leading to a prolonged postoperative recovery for the patient.

[0009] Starting from there, the object of the present invention is to provide an improved electrosurgical instrument for thermal cutting of biological tissue. Ideally, the jaw portion of the instrument should preferably not be heated at all or only slightly during use. [Means for solving the problem]

[0010] This objective is achieved by the electrosurgical instrument described in claim 1.

[0011] The surgical instrument according to the present invention is configured, in particular, to thermally cut a patient's biological tissue. The instrument comprises at least two jaws, at least one of which is configured to move relative to the other jaw, toward the other jaw, or away from the other jaw. For example, one of the jaws is configured to pivot about a pivot axis by a pivot device. Alternatively, both jaws can be configured to move toward and away from each other, like forceps. At least one of the jaws comprises a thermal cutting element having a conductive cutting conductor and a conductive return conductor. The cutting element is arranged such that the cutting conductor is not thermally covered at least on the side of the jaw facing the other jaw, and the return conductor is surrounded (entirely) by an insulator. The cutting conductor can be made of bare metal or covered with a thermally conductive electrically insulating coating. For example, the coating can have hydrophobic properties, thereby preventing the cutting conductor from adhering to the patient's biological tissue.

[0012] The cut conductor and return conductor can be connected to and supplied with current from a current source. Such a current source may be a DC source, but it may also be an AC source, such as a high-frequency (HF) source.

[0013] A feature of the present invention is that the return conductor has lower electrical resistance, and preferably higher thermal conductivity, than the cut conductor. The insulator is configured to be electrically and thermally insulating, and as a result, while supplying current to the cut element, heat is mainly generated on the cut conductor, where it is particularly prevented from being dissipated backward by the insulator. For example, the insulator can be made of silicone. Since the return conductor has lower electrical resistance than the cut conductor while supplying current to the cut element, the return conductor can generate considerably less heat than the cut conductor. In particular, the return conductor comprises a core covered with a coating (return conductor core). The coating can affect the properties of the return conductor, in particular, the electrical resistance and thermal conductivity of the return conductor. Preferably, the electrical resistance of the return conductor can be configured to be lower than the electrical resistance of the return conductor core due to the coating. Preferably, the return conductor core is made of the same material as the cut conductor.

[0014] The cut conductor and the return conductor are electrically and physically connected to each other. In particular, in the direction of conduction, i.e., in the direction in which current flows during use of the cutting element and in the opposite direction, the return conductor has a higher thermal conductivity than the cut conductor. The coating of the return conductor has a higher thermal conductivity than the base material of the return conductor core. The coating results in the electrical resistance of the return conductor, i.e., the total composition of the return conductor core and coating, being lower than that of the cut conductor. Furthermore, due to the coating, the return conductor has a higher thermal conductivity than a return conductor core without coating. Due to the high thermal conductivity of the return conductor, the heat generated in the return conductor can be dissipated, which is particularly advantageous when the return conductor has a particularly small cross-section. In this way, it is possible to avoid overheating of the return conductor (the total composition of the return conductor core and coating). In this way, the jaw can be configured particularly elongated and particularly flat without transferring excessive heat locally from the return conductor to the support of the jaw and thus to the outside of the jaw during cutting.

[0015] The cutting conductor and the return conductor are preferably a single monolithic body. The monolithic body is configured, for example, at least substantially in a U-shape, and the cutting conductor and the return conductor can each form one leg of a U-shaped cutting element.

[0016] The jaw comprises a rectangular support portion extending from a proximal region, where a hinge device for pivotally supporting the other jaw can be arranged, to a distal end region. The support portion can define a holding space in which the cutting element is preferably arranged vertically. Thereby, the cutting conductor is arranged above the return conductor.

[0017] The cutting conductor and the return conductor are preferably made of the same basic material. Different coatings can be provided on the return conductor at different locations. Individual locations, such as the cutting conductor, connection sections, etc., can also be free of coatings.

[0018] The U-shaped cutting element preferably opens towards the proximal region of the jaw. At the proximal end, a connection section or a connection element can be electrically connected to the cutting conductor and the return conductor, thereby connecting the cutting element to the supply line. Via the supply line, the cutting element can be connected to a current source and supplied from the current source. Due to the monolithic configuration of the cutting element, in particular in the distal end region of the jaw where the cutting conductor is physically connected to the return conductor, i.e., electrically and thermally connected, no connection joints, such as welding joints or brazing joints, are necessary. The risk of conductor breakage between the cutting conductor and the return conductor is significantly reduced during the use of the instrument and the mechanical stress on the associated cutting element.

[0019] The return conductor core is preferably provided at least partially with a coating extending in the longitudinal direction. This coating preferably covers the entire outer circumference of the return conductor core. The coating enables the return conductor core and the cutting conductor to be manufactured monolithically from one material, thereby eliminating the need for additional elements to connect the two conductors (the cutting conductor and the return conductor). It is preferable that the entire return conductor is provided with a coating, so that the heat generated in the return conductor can be dissipated over a wide area therefrom by the coating.

[0020] The coating preferably consists of a material having a lower electrical resistivity than the base material of the cutting conductor. Furthermore, the material of the coating preferably has a higher specific heat conductivity than the base material of the cutting conductor. The cutting conductor and the return conductor can consist of the same material, such as a nickel-based alloy containing stainless steel, iron, molybdenum, niobium, cobalt, manganese, copper, aluminum, titanium, silicon, carbon, sulfur, phosphorus and boron, or an iron-chromium-aluminum alloy. The coating can consist of, for example, copper, silver, and / or aluminum. The specific heat conductivity of the coating is particularly higher than 200 W / (m·K).

[0021] In particular, the cutting conductor has a larger cross-sectional area and a higher specific resistance than the return conductor, so that the electrical resistance of the cutting conductor is higher than the electrical resistance of the return conductor provided with a coating having a lower electrical resistance and a higher heat conductivity, and is preferably considerably higher. Thereby, the heat generated by the cutting element can be mainly generated in the cutting conductor, and the return conductor remains at a relatively low temperature and plays a role in heat dissipation.

[0022] In the edge region of the jaw, the jaw preferably comprises at least one sealing electrode arranged at a distance from the cutting conductor respectively. In particular, the cutting conductor is surrounded by the sealing electrode at least on its lateral sides between the distal end and the proximal end of the jaw.

[0023] The sealing electrode is specifically configured to be connected to a current source, such as an HF current source. The sealing electrode and the disconnection element may be supplied by a single HF current source.

[0024] The sealing electrode and cutting conductor can be supplied from a common power source, such as an HF current source. This allows a network provided in the device, such as a transformer, to provide the necessary voltages for the operation of the sealing electrode and cutting element, which are different from the voltage of the power source. The network (transformer) can be part of the device or part of the power generator. However, it is also possible to supply each of the sealing electrode and cutting element with its own (separate) HF current source.

[0025] In particular, the other (second) jaw also comprises at least one sealing electrode in its marginal region. The sealing electrode is preferably identically configured to the sealing electrode of one (first) jaw, so that both are positioned above each other but at a distance from each other when the jaws are closed. The two sealing electrodes are connected to the poles of the supply generator. The second jaw is provided with an elastic counter-pressing body, which the cut conductor strikes during jaw closure, causing the counter-pressing body to elastically deform slightly.

[0026] Preferably, the insulator (and the counter-pressure body as well) is made of a material having a lower thermal conductivity than the cut conductor, thereby greatly insulating the cut conductor from the return conductor. Thus, the heat generated by the cut conductor can be concentrated in a narrow strip of the biological material, where it can be effective.

[0027] A mounting projection surrounded by an insulator can be configured on the cut conductor. Preferably, the mounting projection comprises at least one undercut section. The mounting projection is particularly entirely surrounded by an insulator, thereby preventing the cut conductor from being mechanically detached from the insulator or pulled out from the insulator, for example, when the cut conductor adheres to biological tissue and the instrument is moved further.

[0028] At least one distance element can be placed between the cut conductor and the return conductor. The distance element can be made of an electrically and thermally insulating material, such as ZrO2 or AlO2, or, for example, a ceramic. The material from which the distance element is made can withstand temperatures above 350°C in particular.

[0029] In one embodiment, the distance element may have, for example, an upper (planar) side and a lower (planar) side. Preferably, the upper side of the distance element abuts against the cut conductor and / or its lower side abuts against the return conductor. This prevents the cut conductor from bending in the event of mechanical stress. The insulator, especially if made of silicone, has a certain degree of elastic deformability. The distance element can support the cut conductor on the return conductor, thereby preventing deformation of the cut conductor.

[0030] In another embodiment, multiple distance elements, particularly at least three distance elements, are arranged between the cutting conductor and the return conductor. Each distance element may include, for example, a return conductor cavity on its underside, in which the return conductor is placed, so that the return conductor is at least partially surrounded and held by the distance element, thereby contributing to positioning and securing the cutting element, consisting of the cutting conductor and the return conductor, to one jaw. Preferably, the return conductor cavity is open on one side. This simplifies the assembly of the cutting element on the jaw. Preferably, the multiple distance elements, particularly at least three distance elements, are arranged such that the sides on which the return conductor cavities are open alternate.

[0031] Preferably, the distance elements have support surfaces on which the cut conductor is supported. In particular, the lower side of the cut conductor is supported on the support surface. The distance element includes at least one lateral stopper that protrudes from the support surface and into lateral contact with the cut conductor. Preferably, the distance elements are arranged such that their lateral surfaces alternate where at least one stopper protrudes from the support surface.

[0032] Preferably, the other (second) jaw portion is positioned on the side facing the one (first) jaw portion and comprises a counter-pressing body that defines thereon a (planar) counter-pressing surface for the cutting conductor of the one (first) jaw portion. The counter-pressing body is preferably made of electrically and thermally insulating material. The counter-pressing body is preferably made of a certain degree of elasticity so that it can deform slightly when a portion of the cutting element penetrates it. This elasticity causes the counter-pressing body to come into contact with the cutting conductor during cutting. The cutting conductor protrudes in particular toward the other jaw portion from the surface formed by the insulator. Preferably, the cutting conductor can protrude about 0.10 mm, 0.15 mm or more.

[0033] In particular, the opposing pressing body can be configured such that when the jaw portion is closed, the cutting conductor can penetrate through the cutting conductor (entirely) to a preferably uniform depth.

[0034] Further details of advantageous embodiments of the present invention are derived from the dependent claims, figures and related description. [Brief explanation of the drawing]

[0035] [Figure 1] This is a perspective view of an example of an electrosurgical instrument according to the present invention. [Figure 2] This diagram shows in detail an example of a tool located at the distal end of the instrument. [Figure 3] This is a top view of an example of the first jaw portion of the instrument. [Figure 4] This is a top view of an example of the second jaw portion of the instrument. [Figure 5] This figure shows in detail an example of a cutting element having part of an insulator. [Figure 6] This is a longitudinal section view of an example of the two jaw sections of a closed appliance. [Figure 7] This is a cross-sectional view of an example of the two jaw portions of a closed appliance. [Figure 8] This is a cross-sectional view of another example of the two jaw sections of the closed appliance. [Figure 9] This is a longitudinal section of another example of the first jaw portion of the instrument. [Figure 10] This is a detailed view of a section element with a distance element, as seen from one side. [Figure 11] This is a detailed view of a section element with a distance element, seen from a different side. [Figure 12] This is a cross-sectional view of the mandibular portion of the device. [Modes for carrying out the invention]

[0036] Figure 1 shows an example of an electrosurgical instrument 10 configured to thermally cut a patient's biological tissue. The instrument 10 has a longitudinal shank 11 extending from its proximal end 12 to its distal end 13. A tool 14 is positioned at the distal end 13 of the electrosurgical instrument 10, comprising a first jaw 15 and a second jaw 16, thereby allowing at least one of the two jaws 15, 16 to move relative to the other.

[0037] A handle 17 for operating a tool 14 is positioned on the proximal end 12 of the electrosurgical instrument 10. The shank 11 may have a channel through which an electrical supply line 18 extending from the proximal end 12 to the distal end 13 of the instrument 10 can be routed to electrically supply power to the tool 14, which has a cutting electrode and a sealing electrode located inside. In addition, one or more control wires may be provided on the shank 11, at least one of which is connected to at least one of two jaws 15, 16 for opening and closing the jaws. An instrument supply line 19 is mounted on the handle 17 of the instrument 10, which can connect the electrosurgical instrument 10 to a supply device for supplying voltage, current or other media to the instrument 10.

[0038] Figure 2 shows a detailed view of the tool 14 positioned at the distal end 13 of the shank 11. The two jaws 15, 16 can be opened and closed like forceps. For this purpose, at least one of the two jaws 15, 16, the second jaw in this embodiment, is pivotable relative to the fixedly positioned first jaw 15 by a hinge device indicated by a pivot axis 21. Alternatively, both jaws 15, 16 can be pivotably positioned toward and away from each other. The hinge device can be implemented by one or two pivot bearings, a slotted guide, a spring hinge, and the like.

[0039] A thermal cutting element 22 for thermally cutting biological tissue is positioned in at least one of the two jaws 15, 16. In Figure 2, the jaws 15, 16 are configured to be particularly narrow and elongated and at least substantially linear. Unlike the illustration in Figure 2, the jaws 15, 16 may also have a slight curve, thereby allowing the electrosurgical instrument to prepare, for example, organs or other biological tissues. The electrosurgical instrument 10 plays a role in cutting, separating, closing, and sealing blood vessels, such as blood vessels.

[0040] The first jaw portion 15 is formed by a rigid support portion 23, for example, made of metal, which may have an electrically insulating material on its outer surface 24. Alternatively, the support portion 23 may also be made of a mechanically stable, low-flexibility or non-flexibility, electrically insulating plastic, either partially or entirely. The support portion 23 may also be a composite component, for example, made of a metal inlay overmolded with plastic.

[0041] The support portion 23 of the first jaw portion 15 is provided with sealing electrodes 26 and 27 along its two marginal regions 25, which can be connected to a generator by lines (not shown). The two sealing electrodes 26 and 27 can be physically and electrically connected to each other in the distal end section 28 of the first jaw portion 15, as shown in Figure 2. However, alternatively, separate sealing electrodes 26 and 27 that are at equal or different potentials and are not physically connected within the distal end section 28 may be provided.

[0042] The second jaw portion 16 also includes a support portion 29, which may also be made of metal, or it may be made of plastic or a metal-plastic composite. The support portion 29 supports sealing electrodes 30, 31 at its outer edge, extending from the region 32 near the joint to the distal end section 28. The contour of the support portion 29 of the second jaw portion 16 coincides with the contour of the first jaw portion 15. When both jaw portions are closed, the sealing electrode 26 is aligned with the sealing electrode 30. In addition, the sealing electrode 27 is aligned with the sealing electrode 31. Furthermore, the sealing electrodes 30, 31 can be electrically and physically connected to each other at the distal end section 28 of the second jaw portion 16.

[0043] Figure 3 shows a top view of the first jaw portion 15. The support portion 23 of the first jaw portion 15 includes a groove 33 in which the cutting element 22 is located. The cutting element 22 is surrounded by an insulator 34 such that the upper surface of the cutting element 22 in which the cutting conductor 36 is placed protrudes from the insulator 34.

[0044] Figure 4 shows a top view of the second jaw portion 16. In this embodiment, the cutting element 22 is not located on the second jaw portion 16. Alternatively, the cutting element 22 may also be located on the second jaw portion 16, similar to the first jaw portion 15. In the example shown in Figure 4, the support portion 29 of the second jaw portion 16 is provided with a groove 35 in which the opposing pressing body 50 is located.

[0045] Figure 5 shows the cutting element 22 in a longitudinal section. The cutting element 22 comprises a cutting conductor 36 and a return conductor 37. The cutting conductor 36 extends from a region 32 near the joint to the distal end section 28. In the region 32 near the joint, the cutting conductor 36 and the return conductor 37 can be electrically connected, for example, by a morph-fit and / or friction-fit. For example, the cutting conductor 36 and the return conductor 37 can be connected by silver wire without requiring an additional connecting element. In the example shown in Figure 5, a connecting element 38 is attached to the cutting conductor 36. The connecting element 38 can be a connecting sleeve, for example, a crimp sleeve. The return conductor 37 extends from the distal end section 28 to the region 32 near the joint.

[0046] The return conductor 37 is positioned below the cutting element 36. In the distal end section 28, the cutting conductor 36 and the return conductor 37 are electrically and physically connected. In the region 32 near the junction, the return conductor 37 also includes a connecting element 38, as shown in the example in Figure 5. The cutting conductor 36 and the return conductor 37 can be connected to a current source via the connecting element 38.

[0047] The current source can be the same current source used for the sealing electrode, and an adaptive network can be placed between the current source and the disconnection element. The adaptive network can be configured to distribute the power supplied by the current source to the sealing electrode and the disconnection element, and to adapt the supplied voltage to the required voltage. The same applies to the supplied current and the required current. However, the disconnection element 22 can also be connected to a separate current source.

[0048] A distance element 39 is positioned between the cut conductor 36 and the return conductor 37, and the distance element 39 is made of a thermal insulating material and an electrical insulating material. The distance element 39 is configured to be at least substantially planar, with its upper side in contact with the lower side of the cut conductor 36 and its lower side in contact with the upper side of the return conductor 37. The distance element 39 serves to prevent the cut conductor 36 from bending when mechanical stress is applied, but instead the cut conductor 36 is supported on the return conductor 37 via the distance element 39. The distance element 39 is positioned between two positioning projections 40, which project from the lower side of the cut conductor 36 toward the return conductor 37 but do not contact the return conductor 37. As shown in Figure 5, on the side of the cut conductor 36 facing the return conductor 37, there are further two mounting projections 41 that project from the cut conductor 36 toward the return conductor 37. The mounting projections 41 include an undercut section 42.

[0049] The return conductor 37 includes a core 52 surrounded by a coating 43, and as a result, the return conductor 37 has lower electrical resistance than the cut conductor 36. In addition, the return conductor 37 has greater thermal conductivity in the direction of current flow than the cut conductor 36.

[0050] The coating 43 preferably completely covers the core 52 of the return conductor 37 in the circumferential direction. In the example shown in Figure 5, the coating 43 extends from the distal end section 28 to the region 32 near the junction. Unlike the illustration in Figure 5, the coating 43 may also be present only in the section of the core 52 of the return conductor 37, preferably adjacent to the distal end section 28, in which the cut conductor 36 is electrically and physically connected to the return conductor 37. The return conductor 37 and a portion of the cut conductor 36 are preferably embedded in the insulator 34 such that only the upper part of the cut conductor 36 protrudes from the insulator 34.

[0051] In Figure 6, the tool 14 is shown cut longitudinally in a side view. The cutting element 22 is embedded within the insulator 34 such that the return conductor 37 is entirely surrounded by the insulator 34. The insulator 34 has a plurality of insulator feet 51 on its underside, each of which has one undercut section 44. The insulator feet 51 are positioned in a location where an opening 46 is provided within the support portion 23 of the first jaw portion 15.

[0052] Regarding the assembly of the cutting element 22, the cutting element 22 is overmolded with an insulator 34. The insulator foot 51 further comprises a tapered section 45, which can pull the insulator 34 in the insulator foot 51 through the opening 46 in the support 23 of the first jaw 15 until the undercut section 44 seats inside the opening 46. The undercut section 44 causes the insulator 34, including the cutting element 22, to seat in a morph-fit manner in the support 23 of the first jaw 15. After inserting the insulator 34 into the support 23, the insulator foot 51 can be cut.

[0053] Figure 7 shows a cross-section of the tool 14 of the instrument 10. Up to this point, the above description has been applied with reference to the already introduced reference numerals. The tool 14 is shown with the jaws 15 and 16 closed. The cutting conductor 36 overlaps with the counter-pressure body 50 at least partially when the jaws 15 and 16 are closed. The counter-pressure body 50 plays a role in ensuring that the patient's tissue to be cut is in contact with the cutting conductor 36 in order to enable a clean cut.

[0054] Furthermore, the cross-sectional area A36 of the cut conductor 36 is larger than the cross-sectional area A37 of the return conductor 37. In the embodiment shown in Figure 7, the cross-sectional area A37 of the return conductor 37 is approximately half the cross-sectional area A36 of the cut conductor 36. In the example shown in Figure 7, the return conductor 37 is further coated with a coating 43 along its entire circumference. As a result of the smaller cross-sectional area A37 of the return conductor 37, firstly, the electrical resistance of the uncoated return conductor 37 is higher than that of the cut conductor. However, since the coating 43 is made of a particularly low-ohmic material, the electrical resistance of the return conductor 37 is lower than that of the cut conductor 36, despite its smaller cross-sectional area A37. For example, the width of the core 52 of the return conductor is between 0.2 and 0.5 mm, and the height is between 0.2 and 0.5 mm. The coating thickness of the coating 43 is between 0.02 mm and 0.08 mm. The width of the cut conductor 36 is between 0.2 mm and 0.5 mm, while the height of the cut conductor 36 can be between 0.4 mm and 1.00 mm. The coating can be made of, for example, copper, aluminum, or silver. Copper has a resistance of approximately 0.01 Ω·mm. 2 This includes electrical resistivity of Ω / m and thermal conductivity between 240 and 380 W / m·K. However, silver and aluminum have a resistivity of approximately 0.016 Ω·mm. 2 / m and 0.026Ω·mm 2 The electrical resistivity is approximately 0.7 to 1.5 Ω·mm², and the thermal conductivity is approximately 429 W / m·K and 160 W / m·K. The cut conductor 36 and / or return conductor 37 are preferably made of stainless steel, Inconel or Kanthal-D, and have a resistance of approximately 0.7 to 1.5 Ω·mm². 2 It has relatively high resistivity between / m and relatively low thermal conductivity between 15 and 25 W / m·K.

[0055] The insulator 34 is thermally and electrically insulating. As a result, heat in the central region between the jaws 15 and 16 is maintained mainly on the cut conductor 36. Conversely, heat transferred to the distal end section 28 of the first jaw 15 due to heat conduction to the return conductor 37 is distributed particularly by the coating 43 of the return conductor 37 and can be dissipated over a wide area without creating localized hot spots. This allows the jaws 15 and 16 to be made particularly elongated, thin, and flat without heating the outside of the jaws, especially during prolonged operation.

[0056] Unlike the illustration in Figure 7, the support portion 23 of the first jaw portion 15 may have a pocket 47 on its underside around the opening 46 so that the insulating foot portion 51 can be cut in the same plane as the support portion 23. This is shown in Figure 8.

[0057] Figures 9 to 12 show another example of the jaw structure. In the examples shown in Figures 9 to 12, the above description applies accordingly with reference to the reference numerals.

[0058] This example is distinguished from the previously mentioned example in that the first jaw portion 15 has only two insulating legs 51 and has three distance elements 39a, 39b, and 39c. The cut conductor 36 includes different undercut sections 42a, 42b, and 42c, and the undercut sections can be located inside the insulator 34 (compared to undercut section 42a) or inside the distance elements 39b, 39c (compared to undercut sections 42b and 42c).

[0059] Together with the undercut sections 42b and 42c, the distance elements 39a, 39b, and 39c form a shape fit, securing the cut conductor 36 and thereby preventing the cut conductor 36 from being lifted due to tissue adhesion. The distance elements 39a, 39b, and 39c avoid electrical contact between the cut conductor 36 and the return conductor 37, as well as with the support portion 23 of the first jaw portion 15.

[0060] As shown in Figure 10 from one side and in Figure 11 from the other side, the distance elements 39a, 39b, and 39c are further provided with lateral stoppers 53 that can ensure the central positioning of the cutting element 22 in the first jaw portion 15. The lateral stoppers 53 are laterally adjacent to the support surface 58 where the cutting conductor 36, particularly its lower side, can be positioned and supported. The distance elements 39a, 39b, and 39c each include a return conductor cavity 54 opening on one lateral side. The return conductor cavity 54 can be alternately inserted onto the cutting conductor 36 and the return conductor 37, thereby achieving the central positioning of the first jaw portion 15 in the support portion 23. The proximal distance element 39c further includes a base plate 55 fitted to the support portion 23, the base plate 55 tapering toward the distal end 28 of the first jaw portion 15, so that the cutting conductor 36 can also be positioned in the center of the enlarged proximal region 32 near the joint.

[0061] Additionally, the distance elements 39a, 39b, and 39c include transverse and longitudinal cavities 56, 57 through which the material of the insulator 34 can flow during manufacturing. In this way, a morphological fit can be formed between the distance elements 39a, 39b, and 39c and the insulator 34.

[0062] Combinations of different morphological matings, as well as morphological matings between the undercut sections 44 of the insulator 51, can also prevent the cutting element 22 from lifting.

[0063] The materials of the distance elements 39a, 39b, and 39c can be ceramics with electrical and thermal insulating properties, thereby preventing the generated heat from being distributed to the cutting element 22, and instead primarily being directed to the tissue at the expected location, i.e., the cutting conductor 36.

[0064] The present invention relates in particular to an electrosurgical instrument 10 for thermal cutting of a patient's biological tissue. The instrument 10 comprises two jaws 15, 16, wherein at least one of the jaws 15 is configured to move toward and away from the other jaw 16. At least one of the jaws 15 comprises a thermal cutting element 22 having a conductive cutting conductor 36 and a conductive return conductor 37 electrically connected to each other. The cutting element 22 is arranged such that the cutting conductor 36 is at least not thermally covered on the side of one jaw 15 facing the other jaw 16, and the return conductor 37 is surrounded by an insulator 34. The return conductor 37 has lower electrical resistance in the direction of current flow and preferably higher thermal conductivity than the cutting conductor 36. In doing so, during the supply of current to the cutting element 22, the return conductor 37 generates a considerably lower amount of heat and temperature than the cutting conductor 36, and the return conductor 37 can be used for heat dissipation. [Explanation of Symbols]

[0065] 10 Electrosurgical Instruments 11 Shank 12. Proximal end of the device 13. Distal end of the device 14 Tools 15 First jaw 16. Second jaw 17 Handle 18 Electrical supply lines 19. Equipment supply line 20 Feeding device 21 Pivot axis 22 Cutting elements 23 Support part of the first jaw 24. Outer side of the support 25 Marginal region of the jaw 26,27 Sealing electrodes of the first jaw region 28. Distal section of the jaw 29 Support part of the second jaw 30,31 Sealing electrodes of the second jaw region 32 Region near the joint 33. Groove of the first jaw 34 Insulator 35. Groove of the second jaw 36 Cut conductor 37 Return conductor 38 connection elements 39 Distance elements 40 Positioning protrusion 41 Mounting protrusion 42 Undercut Sections 43 Coating 44. Undercut section of the insulator foot 45 Tapered section of the insulating foot 46 Opening within the support portion of the first jaw 47 pockets 48 RF Generators 49 Transformer 50 Opposing pressure body 51 Insulator foot 52 Core of the return conductor 53. Lateral stopper 54 Return conductor cavity 55 Bottom plate 56 Transverse cavity 57 Longitudinal cavity 58 Support surface A36 Cross-sectional area of ​​a cut conductor A37 Cross-sectional area of ​​the return conductor

Claims

1. An electrosurgical instrument (10) for thermal cutting of biological tissue in particular, having at least two jaws (15, 16), wherein at least one of the jaws (15, 16) is configured to move toward and away from the other jaw (16, 15) relative to the other jaw (15, 16), and at least one of the jaws (15, 16) comprises a thermal cutting element (22) having a conductive cutting conductor (36) and a conductive return conductor (37) connected to the cutting conductor (36), The cutting conductor (36) is not at least partially, at least thermally, covered on the side of one jaw portion (15) facing the other jaw portion (16), and the cutting element (22) is arranged such that the return conductor (37) is surrounded by the insulator (34). An electrosurgical instrument (10) wherein the return conductor (37) has a lower electrical resistance than the cut conductor (36).

2. The electrosurgical instrument (10) according to claim 1, characterized in that the return conductor (37) has a higher thermal conductivity than the cut conductor (36).

3. The electrosurgical instrument (10) according to claim 1 or 2, characterized in that the cutting conductor (36) and the return conductor (37) are preferably a single monolithic body configured in at least substantially a U shape.

4. The electrosurgical instrument (10) according to claim 3, characterized in that the cut conductor (36) and the return conductor (37) are thermally and electrically connected to each other within a section preferably located in the distal end section (28) of the jaw portion (15).

5. The electrosurgical instrument (10) according to claim 1, wherein the core (52) of the return conductor (37) is at least partially provided with a coating (43), and the coating (43) is preferably made of a material having lower electrical resistivity and / or higher specific thermal conductivity than the base material of the cutting element (22).

6. The electrosurgical instrument (10) according to claim 1, characterized in that the cut conductor (36) has a larger cross-sectional area than the return conductor (37).

7. The electrosurgical instrument (10) according to claim 1, characterized in that the jaw portion (15, 16) comprises at least one sealing electrode (26, 27) within the marginal region (25), the at least one sealing electrode (26, 27) is separated from the cut conductor (36), and on the lateral side, the cut conductor (36) is preferably surrounded by the sealing electrode (26, 27) between the distal end and proximal end of the jaw portion (15) and / or in the distal end section (28) of the jaw portion (15).

8. The electrosurgical instrument (10) according to claim 7, characterized in that the other jaw portion (16) is provided with at least one sealing electrode (30, 31) within its marginal region (25), and the at least one sealing electrode (30, 31) is arranged in the same manner as the sealing electrodes (26, 27) of the first jaw portion (15).

9. The electrosurgical instrument (10) according to claim 8, characterized in that the sealing electrodes (26, 27; 30, 31) are positioned above each other, but are positioned at a distance from each other when the jaw portions (15, 16) are closed.

10. The electrosurgical instrument (10) according to claim 1, characterized in that the insulator (34) is made of a material that is electrically insulating and has a lower thermal conductivity than the cutting element (22).

11. The electrosurgical instrument (10) according to claim 1, characterized in that at least one mounting projection (41) is configured on the cut conductor (36), the at least one mounting projection (41) is surrounded by the insulator (34), and the at least one mounting projection (41) preferably comprises an undercut section (42) surrounded by the insulator (34).

12. The electrosurgical instrument (10) according to claim 1, characterized in that at least one distance element (39, 39a, 39b, 39c) is positioned between the cut conductor (36) and the return conductor (37), and the at least one distance element (39, 39a, 39b, 39c) is made of a material that is electrically and thermally insulating.

13. The electrosurgical instrument (10) according to claim 12, characterized in that the at least one distance element (39) comprises an upper and a lower side, and the distance element (39) preferably contacts the cut conductor (36) on the upper side and / or contacts the return conductor (37) on the lower side.

14. The electrosurgical instrument (10) according to claim 12, characterized in that the at least one distance element (39a, 39b, 39c) comprises a return conductor cavity (54), and the return conductor (37) is disposed inside the return conductor cavity (54) such that it is at least partially surrounded and held by the distance element (39a, 39b, 39c).

15. The electrosurgical instrument (10) according to claim 14, characterized in that the at least one distance element (39a, 39b, 39c) has a support surface (58) on which the cut conductor (36) is placed, and the distance element (39a) has at least one lateral stopper (53) that protrudes from the support surface (58) and the cut conductor (36) abuts laterally against it.

16. The electrosurgical instrument (10) according to claim 1, wherein the other jaw portion (16) comprises a counter-pressing body (50) positioned on the side facing the one jaw portion (15), and the counter-pressing body (50) defines a counter-pressing surface for the cutting conductor (36) of the one jaw portion (15).

17. The electrosurgical instrument (10) according to claim 1, characterized in that the cut conductor (36) protrudes in a direction toward the other jaw portion (16) from the surface formed by the insulator (34).

18. The electrosurgical instrument (10) according to claim 16 or 17, characterized in that the opposing pressing body (50) and the cutting conductor (36) overlap along the cutting conductor (36) to a preferably uniform depth when the jaw portions (15, 16) are closed, and the cutting conductor (36) penetrates the opposing pressing body (50).

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