Short-circuit protected electrode instrument and resectoscope

Description

[0001] The invention relates to electrode instruments for use in a resectoscope of the type mentioned in the preamble of claim 1 and to a resectoscope of the type mentioned in the preamble of claim 6.

[0002] Electrode instruments and resectoscopes of this type are primarily used in urology for electrosurgical procedures in the bladder and urethra. They are typically used for the resection and vaporization of tissue, for example, tissue in the lower urinary tract. Resectoscopes include an electrode instrument of this type, which is longitudinally slidable within the resectoscope shaft and, after insertion of the resectoscope, can be advanced with its distal working end from the distal end of the shaft. The electrode instrument incorporates an electrosurgical electrode at its distal working end, for example, in the form of a loop or vaporization button (e.g., PlasmaButtons). Examples of such instruments are the OES PRO resectoscopes (Olympus) or other continuous irrigation resectoscopes developed by Iglesias.

[0003] These electrode instruments can be used to resect the prostate or parts of the prostate, for example, in cases of benign prostatic hyperplasia (BPH), i.e., excessive growth of prostate cells. Such prostate enlargement is promoted during the normal aging process by a decrease in androgen and an increase in estrogen levels in the blood. More recently, as an alternative to tissue resection, the prostate tissue has been compressed using implants. This compression is achieved with implants that are anchor-like at both ends and are able to keep the prostate tissue compressed (UroLift® system). By compressing the tissue, the pressure on the urethra is reduced, at least temporarily, allowing urine to flow. A corresponding system is described, for example, in EP 2 164 427 and US 7,645,286 B2.

[0004] However, it has been shown that even after such compression procedures, continued tissue growth may necessitate a resection of the prostate tissue at a later date. If these procedures are performed with standard bipolar electrode instruments, there is a risk of damaging the resectoscope if the conductive implants bridge the insulating gap between the working electrode and the shaft, fork tube, or optics. With particularly thin electrodes, such as loop electrodes, there is an additional risk that the wire will melt and break due to a locally increased current density upon contact with the implant.

[0005] From EP 2 767 250 A1, a resectoscope is known which has a cutting electrode connected to feedback electrodes. At the transition to the cutting electrode, the feedback electrodes are provided with an insulating layer. Furthermore, a non-conductive shield may be provided above the downward-facing cutting electrode.

[0006] In DE 100 28 850 C1, an HF resectoscopic instrument for cutting body tissue is shown, with a loop-shaped cutting electrode and a flat neutral electrode on a loop carrier and an insulator body on the neutral electrode.

[0007] US patent 5,827,274 A discloses a vaporization electrode with partially spherical surfaces. Conductors leading to the electrode may be insulated on the outside.

[0008] US Patent 2014 / 0 378 965 A1 discloses a resectoscope with an electrode instrument. This instrument is provided with a monopolar active electrode, which is shown in the figures, or in a bipolar configuration mentioned only in the text, with a counter electrode. An insulating ceramic layer is provided on the working electrode. In addition, a portion of the working electrode may be provided with an insulating covering. Finally, two alternatively controllable working electrodes, namely a vaporization electrode and a coagulation electrode, may be separated by an insulating layer.

[0009] US patent 2003 / 0 130 655 A1 discloses an electrosurgical instrument for tissue coagulation. A high-frequency voltage is applied between an external active electrode and a counter electrode. An extra-wide, electrically insulating electrode holder is arranged linearly between the electrodes.

[0010] Therefore, there is a need for electrode instruments that reduce the risk of damage to the instrument during procedures on prostate tissue receiving implants. Description

[0011] This problem is solved by a bipolar electrode instrument with the features of claim 1 and a resectoscope with the features of claim 6. According to the invention, it is particularly provided that the working electrode and counter electrode are spaced apart from each other or arranged in such a way that the distance between them cannot be bridged by a conductor having a length of 6 mm or less. This length corresponds to the length of the end pieces or anchor pieces of currently used, aforementioned prostate implants.

[0012] In a first aspect, the invention relates to a bipolar electrode instrument for use in a resectoscope, wherein the electrode instrument has an elongated shaft section through which a first conductor extends, forming a working electrode at the distal end of the electrode instrument that can be acted upon with high-frequency current, wherein a second conductor extends through the shaft section, forming a counter electrode in the distal end region of the electrode instrument, characterized in that the working electrode and the counter electrode are spatially separated from each other in such a way that the distance between them cannot be bridged by means of a straight conductor having a length of 6 mm or less.

[0013] In a second, related aspect, the invention relates to a resectoscope for endoscopic surgery with a sheath tube, characterized in that an electrode instrument according to the invention is mounted longitudinally displaceable within the sheath tube.

[0014] The resectoscope according to the invention is suitable for various procedures in endoscopic surgery, particularly in electrosurgical surgery. For example, the resectoscope can be used for prostate resection. At the same time, the resectoscope can also be used for a variety of other operations, such as bladder resections.

[0015] In its conventional design, the resectoscope according to the invention has a tubular shaft. The resectoscope shaft comprises an elongated outer tube. In addition to the shaft, the resectoscope includes a handle system for holding and operating it, which typically consists of two handle parts.

[0016] The bipolar electrode instrument according to the invention is used as a through-tube instrument in such a resectoscope. For this purpose, the electrode instrument is mounted to be longitudinally displaceable within the resectoscope, preferably within the resectoscope's outer tube. The electrode instrument can be arranged outside an inner tube running within the outer tube, i.e., between the outer tube and the inner tube, or within the inner tube. In addition to the electrode instrument, further through-tube instruments can be arranged in the shaft of the resectoscope. Typically, the resectoscope also includes, for example, a rod-shaped optical system, a light source, and / or an irrigation system.

[0017] The electrode instrument, in its typical design, has an elongated shaft section which, as described above, is arranged within the resectoscope shaft so that it can be moved longitudinally and optionally rotated about its longitudinal axis. The proximal end of the shaft section is functionally connected to a slide of the resectoscope transport mechanism, which can be operated by means of the handle. A working electrode capable of being stimulated with high-frequency current is located at the distal end of the electrode instrument.

[0018] The electrode instrument can have one or two support arms, particularly in the shaft section, on or between which the working electrode and the counter electrode can be held. For example, the working electrode can be securely held between the distal ends of two support arms or at the distal end of one support arm. The working electrode is preferably arranged in such a way that the view of the treatment area is not significantly obstructed.

[0019] Two conductors extend through the support arms or shaft section. The first conductor forms a working electrode (also called an active electrode) at the distal end of the electrode instrument, capable of carrying high-frequency current. The second conductor forms a counter electrode (also called a neutral electrode) at the distal end of the electrode instrument. The working electrode is thus electrically connected to the first conductor, and the counter electrode to the second conductor. The electrodes, however, are not electrically connected to each other or to the other conductor. In this way, during a surgical procedure, the current flows between the two electrodes through the electrically conductive tissue or fluid located between them. According to the invention, the electrode instrument is therefore a bipolar electrode instrument.The advantages of bipolar over monopolar instruments are well known to experts. The two conductors are connected, usually via connecting cables, to the two poles of a high-frequency generator.

[0020] Both conductors are electrically conductive and can, for example, be designed as conductor wire. In the shaft section, with the exception of the electrodes, the conductor wire can be electrically insulated from the resectoscope shaft. For this purpose, the support arm(s) can typically have an insulating sheath surrounding the conductor(s), i.e., an electrically insulating casing. The insulating sheath can be a hollow cylinder in which the conductor(s) run. It is also conceivable to surround only one of the conductors with an insulating sheath and the other not at all or only partially. Such solutions are known to experts in the field. At the proximal end of the support arm, the conductor is connected to a power source via the proximal section of the resectoscope, as described above.

[0021] The counter electrode is spaced apart from the working electrode. This distance is sufficient to electrically isolate the two electrodes from each other. A distance of approximately 2 mm is generally sufficient for this purpose. The counter electrode can therefore be 2 mm or more away from the working electrode, preferably 3 mm or more, and particularly preferably 4 mm or more. Preferably, the counter electrode is arranged longitudinally, i.e., along the longitudinal axis of the electrode instrument, at the same level or proximal to the working electrode.

[0022] The working electrode can cut through tissue when subjected to high-frequency radiation and can be used, for example, to remove a tumor or excess prostate tissue. For this to occur, the electrode instrument, especially the working electrode, must be moved in a suitable cutting motion while the high-frequency generator is switched on.

[0023] The working electrode can have various shapes known in the field of high-frequency surgery. For example, it can be designed as a loop electrode, a band electrode, or a vaporization button. A vaporization button is a partially spherical, usually hemispherical, working electrode, also known as a plasma button. Preferably, the working electrode is such a partially spherical vaporization button.

[0024] According to the invention, the working electrode and the counter electrode are spatially separated from each other in such a way that the distance between them cannot be bridged by a straight conductor, for example, a rod-shaped conductor, with a length of 6 mm or less. In other words, the arrangement of the working and counter electrodes prevents a conductive connection, and thus a short circuit, from forming between the two electrodes through simultaneous contact with another conductor. Bridging the distance between the two electrodes is therefore understood here to mean the creation of an electrically conductive connection between the two electrodes. This additional conductor, which is not part of the electrode instrument or the resectoscope, can, for example, be part of an electrically conductive implant. The conductor can therefore also be referred to as an external conductor.The external conductor is not tissue or liquid, but is usually made of an electrically conductive metal or an alloy containing one. The external conductor is essentially straight and has no significant bends.

[0025] Six millimeters corresponds to the shortest anchor length of currently used prostate implants. However, in many cases, implants with an anchor length of 8 millimeters are used. In one embodiment of the invention, the working electrode and the counter electrode are therefore spatially separated from each other in such a way that the distance between them cannot be bridged by means of a straight conductor, for example a rod-shaped one, which has a length of 8 millimeters or less.

[0026] The counter electrode is located in the distal end region of the electrode instrument. This means that the counter electrode is located, for example, in the distal third, preferably in the distal fifth, or more preferably in the distal tenth of the electrode instrument, but does not necessarily have to be located directly at the distal end of the instrument. As a rule, the counter electrode will be located relatively close to the working electrode, but electrically insulated from it.

[0027] In preferred embodiments, according to the invention, a short circuit caused by a conductor external to the instrument is prevented by ensuring that the distance between the working electrode and the counter electrode is greater than 6 mm. Since the maximum length of the anchors of the smallest commonly used implants is 6 mm, this sufficiently reduces the risk of a short circuit between the working and counter electrodes. The distance between the working electrode and the counter electrode can be greater than 6 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, or 15 mm. Preferably, the distance is greater than 8 mm, as this corresponds to the length of the anchors of commonly used implants.In other words, the distance between the working electrode and the counter electrode is between 6 mm and 20 mm, between 8 mm and 20 mm, between 10 mm and 20 mm, between 11 mm and 20 mm, between 12 mm and 20 mm, between 13 mm and 20 mm, between 14 mm and 20 mm, or between 15 mm and 20 mm. A maximum distance of 15 mm can also be provided. It is understood that the term "between" in these range specifications excludes the aforementioned lower and upper limits. The distances mentioned are longer than currently common distances between the working electrode and the counter electrode, which are generally around 4 mm. According to the invention, the support arm(s) are, for example, extended accordingly. However, it is also conceivable to position the counter electrode further proximally on a support arm of conventional length.

[0028] Alternatively or additionally to the described increase in distance, a short circuit between the working electrode and the counter electrode can be prevented according to the invention by placing an insulator between the two electrodes in such a way that no electrically conductive connection between the two electrodes can be established by means of an external, straight conductor. In these embodiments, in other words, an insulator is spatially arranged between the working electrode and the counter electrode, which intersects all possible straight lines connecting the working electrode and the counter electrode that have a length of 6 mm or less. In preferred embodiments, the insulator intersects all possible straight lines connecting the working electrode and the counter electrode that have a length of 8 mm or less. More preferably, the insulator intersects not only all straight lines connecting the working electrode and the counter electrode that have a length of 6 mm or less, but also all lines connecting the working electrode and the counter electrode that have a length of 8 mm or less.not 8 mm or less, but all possible connecting lines between the working electrode and the counter electrode.

[0029] In this context, connecting lines are defined as all straight lines extending from an outer point of the working electrode to an outer point of the counter electrode. 'Outer points' are defined as all points on the outer surface of the electrodes. Only those lines, or the segment thereof, that could effectively be used to establish an electrically conductive connection between the working electrode and the counter electrode by means of a straight conductor are considered connecting lines. Therefore, connecting lines intersected by the insulator are preferred if, in principle, a straight conductor could be placed on them to establish an electrical connection between the working electrode and the counter electrode. It is understood that the connecting lines in the sense of the invention are virtual, i.e., not actual technical connecting elements.Lines intersected by one or more other insulating elements of the electrode instrument, and on which no electrically conductive connection could therefore be established, are not considered connecting lines. Such other insulating elements could be, for example, the support arm(s), provided they are enclosed in an insulating sheath.

[0030] As described above, the insulator intersects the connecting lines. 'Intersects' in the usual sense of the word means that the insulator crosses or intersects the connecting lines along their path.

[0031] The insulator can comprise one or more insulating elements, for example 1, 2, 3, 4, 5, 6 or more. The insulating elements can be directly adjacent to each other within the insulator, or arranged at some distance from one another.

[0032] Suitable materials for the insulator are known to those skilled in the art. Since the insulator is electrically insulating, essentially any electrically insulating material can be used, although plasma-resistant materials are preferred due to its proximity to the working electrode. The insulator should not be damaged by the working electrode, which is subjected to high-frequency current and heated. For this purpose, the insulator is preferably made entirely, or at least to an extent that ensures its insulating capacity, of an electrically non-conductive, i.e., electrically insulating, material. Such materials are known to those skilled in the art and include, for example, ceramics and plastics. Suitable plastics may, for example, be selected from the group consisting of fluoropolymers and cycloolefin copolymers.

[0033] The insulator can be spaced apart from one or both electrodes. In certain embodiments, however, it is preferred that the insulator be directly adjacent to one or both electrodes, for example, positioned between them. Thus, the insulator can be directly adjacent to the working electrode and / or directly adjacent to the counter electrode. It is conceivable, for example, to position the insulator on the non-spherical side of a vaporization button, i.e., the side of the working electrode facing away from the tissue during a procedure. The counter electrode can then be positioned proximal to the working electrode or on the side of the insulator facing away from the working electrode.

[0034] For this purpose, the insulator can, for example, be designed in a plate-like shape, i.e., have a flat and planar form that is preferably of uniform thickness throughout its entire surface. In this way, the insulator can cross the connecting lines in a material- and space-saving manner, while simultaneously occupying as little space as possible in the direction of the connecting lines.

[0035] The insulator can, for example, have a flat cuboid or L-shaped cross-section. An insulator with an L-shaped cross-section is particularly suitable for shielding the working electrode if it is a vaporization button. The insulator with an L-shaped cross-section can then be positioned such that the vaporization button is enclosed on two sides by the insulator, with one side preferably being the side of the working electrode facing the support arm for attaching the insulator, and the other side intersecting the connecting lines described elsewhere herein.

[0036] Alternatively, if the insulator has a flat, cuboid cross-section, it can, for example, rest adjacent to the working electrode on the side of the working electrode facing the support arm. In this embodiment, the counter electrode could, in turn, be arranged directly on the side of the insulator facing the support arm and away from the working electrode. The counter electrode and working electrode will then not project radially beyond the insulator, and in particular, will not project beyond the insulator in such a way as to create connecting lines between the working and counter electrodes via which an electrically conductive connection could be established using a straight conductor. In this embodiment, the working and counter electrodes can be placed very close together, so that the current path is short when using the electrode.

[0037] It is also conceivable that the working electrode and the insulator are arranged on one side of the electrode instrument, and the counter electrode is arranged on the opposite side of the electrode instrument, with reference to the longitudinal axis of the instrument. Due to this spatial separation of the working and counter electrodes, there are no connecting lines between the electrodes as defined by the invention. Since the working electrodes are often arranged on a support arm or arms that are angled at their distal ends, the counter electrode can, for example, be arranged on the side of the support arm that is opposite the direction of the angle, with reference to the longitudinal axis of the electrode instrument, and in a section of the support arm where the support arm preferably runs substantially parallel to the longitudinal axis of the electrode instrument. Brief description of the characters

[0038] The drawings schematically depict exemplary embodiments of the disclosure. They show: Fig. 1 a schematic side view of a resectoscope according to the invention; Fig. 2 a schematic side view of an electrode instrument according to the invention; Fig. 3 a schematic side view of the distal end region of an electrode instrument from the prior art, wherein the electrode instrument has a vaporization button (button) working electrode; Fig. 4 a schematic side view of the distal end region of an electrode instrument not according to the invention, wherein the electrode instrument has a vaporization button (button) working electrode and the distal end region of the support arm is extended compared to the prior art; Fig.5. A schematic side view of the distal end region of an electrode instrument according to the invention, wherein the electrode instrument has a vaporization button (button) working electrode and an insulator with an L-shaped cross-section that intersects the connecting line between the working electrode and the counter electrode; Fig. 6. A schematic side view of the distal end region of an electrode instrument not according to the invention, wherein the electrode instrument has a vaporization button (button) working electrode and an insulator on one side of the electrode instrument and has a counter electrode on the side of the electrode instrument opposite, with reference to the longitudinal axis of the electrode instrument; and Fig.7A schematic side view of the distal end region of an electrode instrument not according to the invention, wherein the electrode instrument has a vaporization button working electrode and an insulator with a rectangular cross-section, which is arranged adjacent between the working and counter electrodes. Examples of implementation

[0039] Further advantages, characteristics, and features of the present invention will become clear in the following detailed description of exemplary embodiments with reference to the accompanying drawings. However, the invention is not limited to these exemplary embodiments.

[0040] Fig. 1 shows a schematic side view of a resectoscope 12 according to the invention, Fig. 2the electrode instrument 10 arranged therein. The electrode instrument 10 shown in both figures has a working electrode 18 and a counter electrode 22, as well as an insulator 26 which prevents short circuits caused by external conductors 24.

[0041] The resectoscope 12 has a shaft that includes a sheath tube 30, which is in Fig. 1 The outer tube 30 is shown with a dashed line. Inside the outer tube 30 runs an inner tube 32, and inside the inner tube 32 runs the electrode instrument 10. In addition, other elements, not shown here, may run inside the outer tube 30, such as optics, fiber optic bundles and / or flushing tubes.

[0042] The electrode instrument 10 is arranged to be longitudinally displaceable in the inner tube 32 and is protected against transverse displacements, i.e., displacements in the radial direction, by two guide elements 34. The guide elements 34, of which in the Figs. 1 and 2Only one of which is visible at a time, are designed as guide plates that are form-complementary to the inner wall of the inner tube 32 and together take on a semi-cylindrical shape.

[0043] The electrode instrument 10 can be moved axially in distal and proximal directions by actuating a handle 40. It can be extended beyond the distal end of the inner tube 32 and the distal end of the sheath 30. This allows the surgeon to manipulate tissue located further away from the resectoscope tip. For this purpose, the inner tube 32 and / or the electrode instrument 10 are rotatably mounted about their longitudinal axis.

[0044] The electrode instrument 10 has a working electrode 18 at its distal end, which in the illustrated embodiment is designed as a cutting loop. Tissue can be removed by electrosurgical ablation using the working electrode 18. A high-frequency electrical voltage is applied to the working electrode 18 to cut the tissue.

[0045] The electrode instrument 10 further comprises a counter electrode 22 at its distal end and is thus a bipolar electrode instrument in which two electrodes are separately connected to two poles of a high-frequency generator (not shown). Current can flow between these electrodes when they are, for example, immersed in a liquid, such as bladder fluid. The counter electrode 22 is positioned at a distance, for example, proximal to the working electrode 18, as shown. Both electrodes are arranged on the support arm(s) 48 of the electrode instrument 10.

[0046] The support arm(s) 48 of the electrode instrument 10 are rod-shaped. Inside the support arm(s) 48 are a first electrical conductor 16 and a second electrical conductor 24 (not shown), which form the working electrode and the counter electrode, respectively, at their distal ends. The counter electrode 22, for example, is electrically connected to the second conductor 20, but not to the first conductor 16, to which there is only an insulating connection. Thus, the counter electrode 22 is electrically connected only to the second conductor 20, and the working electrode 18 is connected only to the first conductor 16.

[0047] In the distal end region of the electrode instrument 10 are two electrically isolated electrodes 18 and 22, which are connected separately via conductors 16 and 20. Conductors 16 and 20 are connected to separate poles of a high-frequency generator (not shown) via connecting cables. When the high-frequency generator is switched on, different voltage poles are present at the working electrode 18 and the counter electrode 22, and current flows between them through the electrically conductive body fluid.

[0048] When using such bipolar instruments, after the placement of conductive implants, for example in the prostate, there is a risk that a part of an implant touched by both electrodes will lead to a conductive bridge and a short circuit between the working electrode 18 and the counter electrode 22. Therefore, according to the invention, as described in the Figs. 4 to 7shown, provided that the working electrode 18 and the counter electrode 22 are spatially separated from each other in such a way that the distance between them cannot be bridged by means of a straight, instrument-external conductor 24 which has a length of 6 mm or less.

[0049] The illustrated resectoscope 12 features a passive transport mechanism in which the carriage 42 is moved distally against the distal, first handle 38 by relative movement of the handle sections 38, 40, which are arranged proximally to the resectoscope shaft on the handpiece 36, against a spring force applied by a spring bridge 44. During the distal movement of the carriage 42 against the handle 38, the electrode instrument 10 is forcibly moved distally in a manner not shown. When the handle sections 38, 40 are released, the spring force generated by the spring bridge 44 forces the carriage 42 back into its rest position, thereby pulling the shaft of the resectoscope 12, and thus also the electrode instrument 10, in a proximal direction. During the return movement of the carriage 42, an electrosurgical procedure can be performed passively with the electrode instrument 10 without manual force from the surgeon.

[0050] Fig. 3Figure 1 shows a schematic side view of the distal end region of a prior art electrode instrument 10, wherein the electrode instrument 10 has a working electrode 18 designed as a vaporization button (plasma button). The working electrode 18 is arranged at the distal end of a support arm 48, the support arm 48 extending transversely to the longitudinal axis of the electrode instrument 10 in a distal section where the working electrode 18 is located and angled proximally into a section of the distal end region that is parallel to the longitudinal axis of the electrode instrument 10. The counter electrode 22, which is attached to the outer casing of the support arm 48, is arranged in this section that is parallel to the longitudinal axis.The minimum distance between the working electrode 18 and the counter electrode 22 is 6 mm or less, so there is a risk that conductive implant components could cause a short circuit between the counter electrode 22 and the working electrode 18. The support arm 48 is otherwise electrically insulated, i.e., outside of the working electrode 18 and counter electrode 22. In an alternative embodiment, the vaporization button can be held by two support arms 48. In this way, the first conductor 16 can be guided in one support arm 48 and the second conductor 24 in the other support arm 48.

[0051] Fig. 4 Figure 1 shows a schematic side view of the distal end region of an electrode instrument 10 not according to the invention, wherein the electrode instrument 10 has a working electrode 18 designed as a vaporization button. The distal end region of the support arm 48 is opposite the one shown in Figure 1. Fig. 3The support arm 48 shown in the prior art is extended so that the distance between the working electrode 18 and the counter electrode 22 is more than 6 mm. This advantageously eliminates the risk of a potential short circuit due to contact with implant components, since the implant components with which the resectoscope can come into contact are generally no longer than 6 mm. As an alternative to extending the support arm 48, it is also conceivable to extend the distance between the working electrode 18 and the counter electrode 22 in another way, for example by positioning the counter electrode 22 more proximally on the support arm.

[0052] Fig. 5Figure 1 shows a schematic side view of the distal end region of an electrode instrument 10 according to the invention, wherein the electrode instrument 10 has a working electrode 18 configured as a vaporization button. The electrode instrument 10 further comprises an insulator 26 having an L-shaped cross-section. The insulator 26 intersects all virtual connecting lines 28 between the working electrode 18 and the counter electrode 22, along which it would otherwise be possible to establish an electrically conductive connection by means of a straight external conductor 24. Such a conductor 24, which is an anchor part of an implant 50, is also shown by way of example. The implant 50 is anchored in the tissue 46. Only one side of the implant 50, which is T-shaped at both ends, is shown. The tissue 46 can, for example, be prostate tissue that is compressed to keep the ureter open.

[0053] It is evident that no electrically conductive connection can be created by simultaneously touching the working electrode 18 and the counter electrode 22 using the anchor-like, straight end of the implant 50, the conductor 24, since the insulator 26 prevents this. The insulator 26 is arranged with one side adjacent to the tissue-free rear side of the button electrode and with a second section, formed by its L-shaped cross-section, located proximally and laterally to the working electrode 18. This second section of the L-shaped insulator 26 blocks all connecting lines 28 that could potentially be bridged by a straight conductor 24.

[0054] Fig. 6Figure 1 shows a schematic side view of the distal end region of an electrode instrument 10 not according to the invention, wherein the electrode instrument 10 has a working electrode 18 and an insulator 26 on one side of the electrode instrument 10 and a counter electrode 22 on the opposite side of the electrode instrument 10 with reference to the longitudinal axis 2-2 of the electrode instrument 10. The position of the counter electrode 22 in the distal end region of the electrode instrument 10, i.e., the distance of the counter electrode 22 to the distal and proximal ends of the electrode instrument 10, is comparable to or identical with its position in electrode instruments 10 of the prior art, such as the one described in Figure 1. Fig. 3as shown. In contrast to these conventional instruments, however, the counter electrode 22 does not include any parts arranged on the same side of the electrode instrument 10 as the working electrode 18. Instead, an insulator is arranged on this side of the electrode instrument 10 at the level of the counter electrode 22. This insulator can, for example, be semi-cylindrical around the support arm 48 and / or integral with the conventional insulating sleeve of the support arm 48. In preferred embodiments, the insulator 26 is formed by an electrically insulating coating on one side of the support arm 48, for example, by a coating on the underside, which is arranged on the same side of the electrode instrument 10 as the working electrode 18. The counter electrode 22 is formed on the opposite side on the outer wall of the support arm 48.Since the support arm 48 and the insulator 26 are arranged between the counter electrode 22 and the working electrode 18, and the insulator 26 cuts all connecting lines 28 that can be used for potential electrical bridging, there is no risk of a short circuit between the working electrode 18 and the counter electrode 22.

[0055] Fig. 7Figure 1 shows a schematic side view of the distal end region of an electrode instrument 10 not according to the invention, wherein the electrode instrument 10 has a working electrode 18 designed as a vaporization button. The support arm 48 of the electrode instrument 10, which carries the working electrode 18 at its distal end, transitions at an angle in its distal end region into a section that is arranged approximately transversely to the longitudinal axis of the electrode instrument 10 (angled section). In addition to the working electrode 18, the insulator 26 and the counter electrode 22 are also arranged in this angled section. The working electrode 18 and the counter electrode 22 are thus not far apart. The two electrodes are nevertheless reliably electrically isolated from each other by the insulator 26 arranged between the electrodes. All three elements are arranged essentially equicentrically around the at least one support arm 48, i.e.,The central axis (longitudinal axis) of the support arm 48 preferably also represents the central axis of the insulator 26 and the counter electrode 22, and preferably also of the working electrode 18. Furthermore, the width of the three elements ensures that no electrical connection can be established between the working electrode 18 and the counter electrode 22 by an external, straight conductor 24. For this purpose, at least one of the two electrodes is generally narrower on all sides than the insulator 26 arranged between the electrodes. In the example shown, this is the counter electrode 22. The insulator 26 has a substantially cylindrical shape. It is understood that the insulator 26 has corresponding openings for the conductor 16 leading to the working electrode 18.

[0056] Although the present invention has been described in detail with reference to the exemplary embodiments, it is obvious to those skilled in the art that the invention is not limited to these exemplary embodiments, but rather that modifications are possible in such a way that individual features can be omitted or different combinations of the presented individual features can be implemented, provided that the scope of protection of the appended claims is not exceeded. The present disclosure includes all combinations of the presented individual features. Reference symbol list 10 Electrode instrument 48 support arm 12 Resectoscope 50 Implant 14 shaft section 16 first leader 18 working electrode 20 second conductor 22 Counter electrode 24 Director 26 insulator 28 connecting lines 30 sheathing tube 32 Inner tube 34 retaining elements 36 handle 38 handle part 40 handle part 42 Sleds 44 Spring bridge 46 tissue

Claims

1. A bipolar electrode instrument (10) for use in a resectoscope (12), wherein the electrode instrument (10) has an elongated shaft section (14) through which a first conductor (16) extends and forms a working electrode (18) at the distal end of the electrode instrument (10), said working electrode (18) being configured to receive a high-frequency current, wherein furthermore a second conductor (20) extends through the shaft section (14) and forms a counter electrode (22) at the distal end region of the electrode instrument (10), wherein the working electrode (18) and the counter electrode (22) are spatially separated such that the distance between them cannot be bridged by a straight conductor (24) having a length of 6 mm or less, and an insulator (26) is arranged spatially between working electrode (18) and counter electrode (22), the insulator (26) intersecting all possible straight connecting lines (28) between working electrode (18) and counter electrode (22), wherein the insulator (26) has an L-shaped cross-section and the working electrode (18) is enclosed on two sides by the insulator (26), characterized in that one side, preferably for fastening the insulator (26), is the side of the working electrode (18) facing a support arm (48) for the working electrode (18) and the other side intersects the straight connecting lines (28), wherein the working electrode (18) is arranged at the distal end of a support arm (48), and wherein the support arm (48) extends transversely to the longitudinal axis of the electrode instrument (10) in a distal section in which the working electrode (18) is arranged and angled in proximal direction transitions into a section of the distal end region which is arranged parallel to the longitudinal axis of the electrode instrument (10), and wherein the counter electrode (22) is arranged in this section, which is aligned parallel to the longitudinal axis, and is attached to the outer shell of the support arm (48).

2. The electrode instrument (10) according to claim 1, characterized in that the distance between working electrode (18) and counter electrode (22) is greater than 6 mm, preferably greater than 8 mm.

3. The electrode instrument (10) according to one of the preceding claims, characterized in that the insulator (26) is adjacent to the working electrode (18).

4. The electrode instrument (10) according to one of the preceding claims, characterized in that the insulator (26) is plate-shaped.

5. The electrode instrument (10) according to one of the preceding claims, characterized in that the working electrode (18) is a partially spherical vaporization electrode.

6. A resectoscope (12) for endoscopic surgery with a cladding tube (30), characterized in that an electrode instrument (10) according to one of claims 1 to 5 is mounted so as to be longitudinally displaceable inside the cladding tube (30).