Inner shaft, manufacturing method, and resectoscope

Abstract

The present invention relates to an inner shaft for a working element of a resectoscope, said inner shaft comprising a distal end portion and at least three spacer elements which are located on an outer surface of the inner shaft, the spacer elements being distributed in different positions in the region of the distal end portion in such a way that the inner shaft can be guided and / or placed at a distance from an outer shaft in a predefined manner inside the outer shaft at least in the distal end portion. The invention also relates to a method for manufacturing an inner shaft and to a resectoscope.

Description

[0001] Inner shaft, method for production and resectoscope FIELD OF THE INVENTION The present invention relates to an inner shaft for a working element of a resectoscope. Furthermore, the invention relates to a method for producing an inner shaft and to a resectoscope with an outer shaft and such an inner shaft. TECHNICAL BACKGROUND Surgical instruments are used for various applications. For example, they can be used in the field of minimally invasive operations and have a surgical tool. Surgical instruments can be designed as a resectoscope and have a working element that is designed, for example, to guide the surgical tool, such as an electrode. Resectoscopes are known in particular for urological or gynecological applications.The working element with the electrode can be inserted through the urethra into the patient's body as far as the surgical site. At a distal end (i.e. farthest from the user), the electrode has, for example, a cutting loop by means of which tissue can be ablated. The ablated tissue can be removed again through an outflow channel using a rinsing fluid that is guided to the surgical site through an irrigating channel or inflow channel. The inflow and outflow channels enable continuous rinsing, which also serves to keep a viewing window clear in order to always enable a perfect endoscopic view. DE 10056 618 A1 describes a double-shaft endoscope for continuous rinsing, which has an inner shaft enclosing an inflow channel in which an optical system is accommodated, and which has an outer shaft surrounding the inner shaft to form an outflow channel.The inner shaft accommodates a carrier for a resection loop that can be adjusted in the axial direction. The inner shaft and the outer shaft are arranged so that they can move relative to one another. To guide the tool, for example the electrode, the surgical instrument generally has a carriage that is mounted so that it can move along a longitudinal axis of the surgical instrument and is connected to the surgical tool. The carriage can be moved by means of a handle or with an actuator that can be actuated via a robot interface. When an electrode is inserted into the working element, the cutting loop of the electrode can be moved in the axial direction by axially moving the carriage, for example to ablate tissue. To do this, it is necessary that the electrode can be moved relative to the outer shaft. Therefore, the working element with the electrode must be guided at a distance from the outer shaft.In known designs, a spacer element is usually provided in the area of ​​the handle, for example in the area of ​​an electrode clamp, which spacer element is arranged so as to protrude downwards on the working element and is in contact with an inner contour of the outer shaft. This spacer element at the proximal end allows the electrode to be held at a distance from the outer shaft at the distal end. A disadvantage is that the spacer element arranged at the proximal end creates friction when the electrode is moved axially, which is perceived as disruptive when operating the surgical instrument. A further disadvantage is that the working element is mounted in an area which is distant from the distal end at which the electrode is arranged. This can therefore lead to a sinking over the length of the working element up to the electrode relative to the outer shaft.However, to ensure the desired safe and reliable operability, it is desirable to always allow the electrode to be returned to the inner shaft. SUMMARY OF THE INVENTION Against this background, the present invention is based on the object of providing improved mounting of the electrode relative to the inner shaft and relative to the outer shaft. According to the invention, this object is achieved by an inner shaft having the features of patent claim 1, by a method having the features of patent claim 12, and by a resectoscope having the features of patent claim 14.Accordingly, the following is provided: An inner shaft for a working element of a resectoscope with a distal end section and at least three spacer elements that are arranged on an outer surface of the inner shaft, wherein the spacer elements are distributed in different positions in the region of the distal end section such that the inner shaft can be guided and / or placed within an outer shaft, at least in the distal end section, at a predetermined distance from the outer shaft. A method for producing an inner shaft for a working element of a resectoscope, wherein the shape of the inner shaft is produced by erosion. Resectoscope with an outer shaft and an inner shaft, wherein the inner shaft is guided in the outer shaft such that, in the region of a distal end section, the spacer elements prevent the working tool, in particular an electrode, from lowering relative to the outer shaft.The finding underlying the present invention is that lowering of the electrode can be prevented by guiding the working element at the distal end of the surgical instrument. The idea underlying the present invention is to guide the inner shaft in a region at the distal end by at least two spacer elements with point or linear contact with the outer shaft. The spacer elements prevent lowering of the electrode at the distal end because the distance between the inner shaft and outer shaft can be directly adjusted and maintained by the spacer elements in the region of the distal end section, even if the electrode or the working element is axially displaced. Advantageously, the working element is therefore not arranged freely suspended in the region of the distal end, but is guided on the inner shaft.This ensures that when the electrode is moved axially, it can be moved back into the outer shaft. Advantageously, there is no risk of the extended electrode sinking so far due to gravity that retraction becomes impossible. The electrode can therefore be retracted into the outer shaft without any problems at any time. Furthermore, by guiding the working element along the inner shaft, contact between the working element and the outer shaft can be avoided, thus preventing friction that could disrupt the working process when the electrode is extended and retracted. When the working element is moved axially, no frictional resistance occurs between the working element and the outer shaft, as there is no direct contact between these two elements. Instead, the working element is guided along the inner shaft and is thus kept at a distance from the outer shaft, even in the area of ​​the distal end.The inner shaft can have different designs. For example, the inner shaft can have a discontinuous cross-section, with convex and / or concave bulges being able to adjoin straight sections. In particular, the cross-section is symmetrical in a plane or an axis so that the working element can be guided symmetrically along the cross-section. The cross-section preferably has a small wall thickness, in particular 0.09 to 0.20 mm, for example approximately 0.15 mm. The wall thickness can vary in the region of the cross-section. Likewise, the inner shaft can be designed with a constant cross-section all the way around. A spacer element is understood to be an element protruding from the outer surface of the inner shaft. The spacer element can thus be used to guide the inner shaft at a distance from the outer shaft.In particular, the at least two spacer elements are dimensioned such that a distance from the outer shaft can be created around the entire circumference of the inner shaft. This allows a circumferential drainage channel to be formed between the inner shaft and the outer shaft. Since the spacer elements do not run over the entire length of the inner shaft, the drainage channel is only disrupted by the spacer elements in a very short axial section, whereby the returning medium can spread unhindered in the axial direction in front of or behind each spacer element. The spacer elements are preferably rounded so that no damage occurs upon contact with the outer shaft. The distal end section is preferably understood to be an area that is small in relation to the entire length of the inner shaft. The distal end section preferably borders the distal end of the inner shaft.The erosion process is particularly suitable for thin wall thicknesses, such as those implemented in the inner shaft. A thin wall thickness can be considered to be a wall thickness between 0.09 and 0.2 mm. In particular, the wall thickness is between 0.1 and 0.17 mm. Furthermore, very high precision can be achieved through wire erosion. Advantageous embodiments and further developments emerge from the further subclaims and from the description with reference to the figures of the drawing. According to an advantageous embodiment, the spacer elements can be arranged at different circumferential positions on the outer surface of the inner shaft, in particular offset by at least 90° to one another, preferably offset by more than 100° to one another. This allows the inner shaft to be held securely spaced all around from the outer shaft.Preferably, two such spacer elements are identically shaped so that the inner shaft can be held symmetrically with respect to the outer shaft at least in one plane. According to an advantageous embodiment, the spacer elements can be arranged in different positions along a longitudinal axis of the inner shaft. For example, one spacer element can be arranged axially closer to the distal end than another spacer element. Likewise, the spacer elements can be formed with a different axial length. According to an advantageous embodiment, the spacer elements can be formed integrally with the inner shaft. The spacer elements can, for example, be designed as bulges with an open or hollow cross-section on the inside. Likewise, the spacer elements can be made of solid material.According to an advantageous embodiment, at least one spacer element can be dome-shaped and at least one spacer element can be caterpillar-shaped, wherein the caterpillar-shaped spacer element extends over a larger longitudinal section along the inner shaft than the dome-shaped spacer element. Advantageously, the dome-shaped spacer element is formed by a bulge. For example, the dome-shaped spacer element can be arranged closer to the distal end than the caterpillar-shaped spacer element. Caterpillar-shaped is to be understood in particular as an elongated shape aligned in the axial direction of the inner shaft. This can be wedge-shaped in cross-section, for example with a cross-section that is triangular at least in sections, and / or formed integrally with the inner shaft.According to an advantageous embodiment, two caterpillar-shaped spacer elements lying opposite one another in cross-section can be provided, with the dome-shaped spacer element in particular being arranged centrally thereto. This reliably ensures a distance between the inner shaft and the outer shaft around the circumference. According to an advantageous embodiment, the inner shaft can be shaped in at least one region for contacting at least one working tool, with the work tool being able to be guided at a predetermined position at a distance from the outer shaft due to the shape of the cross-section. A region is to be understood as a partial section of the cross-section of the inner shaft which is in particular adapted to the shape of the working element. Contact between the inner shaft and the working element preferably enables the working element to be held at a distance from the outer shaft.For example, the shape of the inner shaft can be used to form a type of holder for the working element in this area. The working element is preferably held immovably in this holder. The working element is preferably held externally, i.e. on an outer surface, on the inner shaft. According to an advantageous embodiment, the inner shaft can form a working channel for guiding and / or fixing a working tool, which is arranged within a cross-section of the inner shaft. This can be formed by one or two elements that are at least partially circular or bowl-shaped. As a result, a further working tool can be guided, in particular clamped, at a distance from the outer shaft.According to an advantageous embodiment, the spacer elements and the at least one region for contacting the at least one working tool can be arranged adjacent to one another on the inner shaft. As a result, the working element can be held externally, i.e. on an outer surface, on the inner shaft, while a spacer element is also arranged on an outer surface of the inner shaft. In this way, the diameter of the outer shaft can be reduced and a surgical instrument with a very small diameter can be provided. According to an advantageous embodiment, the outer surface can be designed to be concave in sections and convex in sections in different circumferential regions. In this way, the region for clamping or holding the working element can be shaped and at the same time a relatively large inner surface for forming an inlet channel can be retained.According to an advantageous embodiment, the wall thickness of the inner shaft can be 0.1 mm to 0.2 mm, in particular approximately 0.15 mm, at least in sections. This makes it possible to provide a very delicate surgical instrument. In particular, the inner shaft has a constant cross-section over its length. The spacer elements are excluded from this; these are arranged in particular only in the region of the distal end section. According to an advantageous embodiment of the method, at least one spacer element can be formed by a stamping process. The spacer element can be subsequently formed onto an already manufactured inner shaft. Furthermore, weight and material can be saved. Advantageously, the shape of the inner shaft and the spacer elements can be manufactured using an additive process. For example, laser sintering can be used to implement metallic 3D printing.According to an advantageous embodiment of the resectoscope, the working tool, in particular the electrode, can be positioned and guided without contact with the outer shaft, in particular retrievable after disengagement. This is achieved by the spacer elements in the region of the distal end section, whereby a lowering of the electrode or the working element at the distal end is prevented. In particular, guiding the working element by the geometry of the inner shaft, i.e., mounting the working element on the inner shaft, can prevent the electrode at the distal end from lowering relative to the inner shaft. The above embodiments and further developments can be combined with one another as desired, where appropriate. Further possible embodiments, further developments, and implementations of the invention also include combinations of features of the invention not explicitly mentioned above or described below with regard to the exemplary embodiments.In particular, a person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention. TABLE OF CONTENTS OF THE DRAWING The present invention is explained in more detail below with reference to the exemplary embodiments shown in the schematic figures of the drawing. These show: Fig. 1 a working element with an electrode from the prior art; Fig. 2 a distal end section of an inner shaft according to one embodiment; Fig. 3 a cross section through a distal end section of a surgical instrument; Fig. 4 a cross section through a distal end section of an inner shaft. The accompanying figures of the drawing are intended to provide a further understanding of the embodiments of the invention. They illustrate embodiments and, in conjunction with the description, serve to explain principles and concepts of the invention.Other embodiments and many of the advantages mentioned will become apparent with reference to the drawings. The elements of the drawings are not necessarily shown to scale. In the figures of the drawing, identical, functionally identical and acting elements, features and components are provided with the same reference numerals unless stated otherwise. DESCRIPTION OF EMBODIMENTS Fig. 1 shows a working element 2' from the prior art. A working tool 9' is arranged in a distal end section 5'. This is designed as an electrode 14'. The electrode 14' is guided in an electrode tube 15'. An electrode clamp is arranged on the working element 2' at the proximal end section opposite the distal end section 5'.At the bottom of the electrode clamp, a spacer element 17' is provided, which contacts the inner contour of an outer shaft (not shown) during installation in a surgical instrument. This allows the working element 2' to be held at a distance from the outer shaft, thereby preventing contact between the electrode and the outer shaft. Disadvantageously, friction occurs between the outer shaft and the spacer element 17' when the electrode is axially displaced within the surgical instrument. Furthermore, in the region of the distal end section 5, the electrode 14' and the working element 2' are arranged so as to be freely suspended. The electrode 14' can therefore sink unintentionally due to gravity alone. A return of the electrode 14' into the outer shaft cannot always be ensured. Fig. 2 shows a distal end section 5 of an inner shaft 1 according to one embodiment. In contrast to the embodiment in Fig.1, three spacer elements 6a to 6c are arranged on the distal end section 5 at three different circumferential positions 7 on an outer surface of the inner shaft 1. Each spacer element 6a to 6c is positioned only slightly spaced from the distal end. The spacer element 6a is closer to the distal end than the spacer element 6c. A further spacer element 6b (shown in Figures 3 and 4) is shaped identically to the spacer element 6c and arranged identically. In this embodiment, the spacer element 6a is arranged centrally in the upper region of the inner shaft 1 and has a dome-shaped design. The spacer element 6a can be produced, for example, by a stamping process. The further visible spacer element 6c is shaped in a bead-like manner along the longitudinal axis 8 of the inner shaft 1. This can be produced, for example, by erosion during the production of the inner shaft 1.The illustrated spacer elements 6a and 6c are arranged on the inner shaft 1 such that the inner shaft 1 can be arranged at a distance from an outer shaft (not shown) all around. In this embodiment, the spacer element 6c is formed with a wedge-shaped cross-section. All spacer elements 6a to 6c are rounded in an area that comes into contact with the outer shaft, so that damage to the outer shaft can be avoided. Fig. 3 shows a cross-section through a distal end section 5 of a surgical instrument. The electrode 14 is guided in an electrode tube 15. The electrode tube 15 is held in a region 18 by the cross-sectional shape of the inner shaft 1 such that a lowering of the electrode 14 and the electrode tube 15 at the distal end section 5, in particular over the entire length of the working element 2, can be avoided.This ensures that the electrode 14 can be returned to the outer shaft 4 at all times. The working tool 9 is held, in particular clamped, in a concave circumferential region 12 of the inner shaft 1, while the spacer elements 6a to 6c are arranged on a convex circumferential region 13 and a straight circumferential region, respectively. The spacer elements 6a to 6c are arranged at different circumferential positions 7a to 7c, spaced from one another. The spacer elements 6a to 6c are placed offset from one another, in particular by at least 90°, preferably at least 100°. The cross-sectional view clearly shows that the spacer elements 6a to 6c are arranged adjacent to the electrode tube 15 on the inner shaft 1. This allows the inner shaft 1 to be kept at a distance from the outer shaft 4 all around, while at the same time ensuring the smallest possible diameter of the outer shaft 4. In Fig.3, an optical element 16 is further held on the inner shaft 1 by the shape of the inner shaft 1. The regions 18 and an upper convex peripheral region 13 serve as clamping sections, see also Fig. 2. Furthermore, a working tool 11 is clamped in a lower region of the inner shaft 1 in the inner shaft 1 by shell-shaped elements. This allows a further working channel to be formed. Fig. 4 shows a cross-section through a distal end section 5 of an inner shaft 1. The position of the spacer elements 6a to 6c can be seen offset by at least 90° to one another around the circumference of the inner shaft 1. A distance between the spacer elements 6b and 6c is greater than a respective distance to the spacer element 6a. In this embodiment, the inner shaft 1 is also designed symmetrically to an axis (here a vertical axis).This allows the working element with the electrode tube to be held or placed symmetrically on the inner shaft in the regions 18. An inlet channel 19 is formed inside the inner shaft 1. The outlet channel is formed between the inner shaft 1 and the outer shaft 4, see Fig. 3. Although the present invention has been fully described above using preferred exemplary embodiments, it is not limited thereto, but can be modified in many ways. For example, the number of spacer elements 6 can differ from the number shown. Furthermore, the spacer elements 6 can be arranged at different circumferential positions 7. Two or three dome-shaped spacer elements 6 are also conceivable. In another embodiment, all spacer elements 6, for example three or four spacer elements 6, can be caterpillar-shaped.Furthermore, the spacer elements 6 can be directly adjacent to the distal end or all arranged at equal distances from the distal end. It is only important that the at least two spacer elements 6 prevent the electrode from sinking directly in the area of ​​the distal end.

[0002] List of reference symbols 1 Inner shaft 2 Working element 3 Resectoscope 4 Outer shaft 5 Distal end section 6 Spacer element 7 Circumferential position 8 Longitudinal axis 9 Working tool 10 Working channel 11 Working tool 12 Concave circumferential area 13 Convex circumferential area 14 Electrode 15 Electrode tube 16 Optical element 17 Spacer element on the electrode clamp 18 Area 19 Inlet channel

Claims

PATENT CLAIMS 1. Inner shaft (1) for a working element (2) of a resectoscope (3), comprising: a distal end section (5); and at least three spacer elements (6) arranged on an outer surface of the inner shaft (1), wherein the spacer elements (6) are arranged in different positions in the region of the distal end section (5) such that the inner shaft (1) can be guided and / or positioned within an outer shaft (4) at a predetermined distance from the outer shaft (4), at least in the distal end section (5).

2. Inner shaft (1) according to claim 1, characterized in that the spacer elements (6) are arranged at different circumferential positions (7), in particular offset from each other by at least 90°, preferably offset from each other by more than 100°, on the outer surface (7) of the inner shaft (1). 3.Inner shaft (1) according to one of the preceding claims, characterized in that the spacer elements (6) are arranged in different positions along a longitudinal axis (8) of the inner shaft (1).

4. Inner shaft (1) according to one of the preceding claims, characterized in that the spacer elements (6) are formed integrally with the inner shaft (1).

5. Inner shaft (1) according to one of the preceding claims, characterized in that at least one spacer element (6a) is dome-shaped and at least one spacer element (6b) is caterpillar-shaped, wherein the caterpillar-shaped spacer element (6b) extends over a larger longitudinal section along the inner shaft (1) compared to the dome-shaped spacer element (6a).

6. Inner shaft (1) according to claim 5, characterized in that two caterpillar-shaped spacer elements (6b, 6c) opposite each other in cross-section are provided, wherein, in particular, the dome-shaped spacer element (6a) is arranged centrally thereto. 7.Inner shaft (1) according to one of the preceding claims, characterized in that the inner shaft (1) is formed in at least one region (18) for contacting at least one working tool (9), wherein the working tool (9) can be guided at a predetermined position spaced apart from the outer shaft (4) by the shape of the cross-section.

8. Inner shaft (1) according to one of the preceding claims, characterized in that the inner shaft (1) forms a working channel (10) for guiding and / or fixing a working tool (11), which is arranged within a cross-section of the inner shaft (1).

9. Inner shaft (1) according to claim 7 or 8, characterized in that the spacer elements (6) and the at least one region (18) for contacting the at least one working tool (9) are arranged adjacent to each other on the inner shaft (1).

10. Inner shaft (1) according to any one of the preceding claims, characterized in that the outer surface (7) is concave and convex in different circumferential regions.

11. Inner shaft (1) according to any one of the preceding claims, characterized in that the wall thickness of the inner shaft (1) is at least in certain sections 0.1 mm to 0.2 mm, in particular about 0.15 mm.

12. Method for manufacturing an inner shaft (1) for a working element (2) of a resectoscope (3), in particular an inner shaft (1) according to any one of the preceding claims, wherein the shape of the inner shaft is produced by electrical discharge machining (EDM).

13. Method according to claim 12, characterized in that at least one spacer element (6) is formed by an embossing process. 14.Resectoscope (3), comprising: an outer shaft (4); an inner shaft (1) according to any one of claims 1 to 11, wherein the inner shaft (1) is guided in the outer shaft (4) such that, in the region of a distal end section (5), the spacer elements (6) prevent the working tool (9), in particular an electrode (14), from lowering relative to the outer shaft (4).

15. Resectoscope according to claim 14, characterized in that the working tool (9), in particular the electrode (14), is positioned and guided without contact with the outer shaft (4), and in particular is retractable after being disengaged.

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