Treatment instrument for an endoscope

Abstract

Treatment instrument (100) for an endoscope, comprising: - a sheath (1) which consists at least partly of a flexible tube; - an actuating wire (2) which is inserted into the sheath (1) and is movable in the longitudinal direction of the sheath; and - a treatment element (3) which is connected to the distal end of the actuating wire (2) and which can be extended from and retracted into the distal end of the sheath (1) by moving the actuating wire (2); - characterized by at least one elastic element (4) which is arranged in the distal end part of the sheath (1) such that it is elastically deformed between the inner surface of the sheath (1) and the outer surface of the actuating wire (2).

Description

The invention relates to a retractable treatment instrument that is inserted into an instrument channel of an endoscope. In general, such a treatment instrument has a treatment element located at the anterior or distal end of the instrument, which is connected to the distal end of an actuating wire inserted into a flexible sheath and movable along the length of the sheath. The treatment element can be extended from and retracted into the flexible sheath. The extension or cantilever length by which the treatment instrument is extended from the anterior end of the flexible sheath can be adjusted by moving the actuating wire longitudinally. Examples of such a treatment instrument are described in publications JP 2002-113016A and JP 2005-270240A. The treatment instrument disclosed in JP 2002-113016A has a screw element at the front end of the flexible sheath, which serves to adjust the extension length of the treatment element from the front end of the sheath. In the treatment instrument described in JP 2005-270240A, the treatment element is designed such that it has a flared section at its proximal part. The width of this section is larger than the inner diameter of a flexible tube forming the sheath, so that the extension length of the treatment element from the leading end of the flexible tube can be held in a set position due to the frictional action that occurs between the edge of the aforementioned flared section and the inner surface of the flexible tube. In the designs described in JP 2002-113016A and JP 2005-270240A, the extension length of the treatment element located at the front end can be adjusted as desired. Because the treatment element can be stably fixed in the set position, the extension length of the treatment element is not altered by a force acting on the treatment element when it contacts the tissue of a body cavity during a diagnostic operation. The treatment instrument described in JP 2002-113016A has the disadvantage of being comparatively complex, as the screw element must be provided at the front end of the flexible sheath. If a screw element with a diameter of approximately 2 mm is provided at the front end of the flexible sheath of the treatment instrument, it becomes impractical to use the instrument with endoscopes. Furthermore, it is impossible to adjust the extension length of the treatment element while the front part of the treatment instrument is inside the body cavity. Therefore, the treatment instrument must be withdrawn from the instrument channel of the endoscope to adjust the extension length of the treatment element. The treatment instrument described in JP 2005-270240A has the disadvantage that the manufacturing costs for the treatment element are comparatively high, since the expanded portion must be formed on the proximal section of the treatment element. Furthermore, there is a possibility that the friction between the edge of this expanded portion and the inner surface of the flexible tube will decrease considerably due to the permanent cross-sectional deformation of the flexible tube, which occurs in the direction in which the inner surface of the flexible tube is stretched by the expanded portion of the treatment element. If the friction decreases as described above, it will be difficult to maintain the extension length of the treatment element at the desired value. DE 10 2006 049 370 A1 discloses a high-frequency cutting instrument for an endoscope. The high-frequency cutting instrument comprises a flexible outer tube, an actuating wire, and a rod electrode that can be moved forwards and backwards and is connected to the proximal end of the outer tube. The outer tube has a fixed stop and an axially displaceable stop. By moving the displaceable stop, the protruding length of the rod electrode can be adjusted. US 2004 / 0172018 A1 discloses a treatment instrument comprising a flexible sheath, a control element movable along the flexible sheath, and a cutting area attached to the distal end of the control element by means of a tubular stop receiving part. The stop receiving part is designed to abut against a stop element located at the distal end of the flexible sheath in order to limit the axial movement of the control element. US 2006 / 0282048 A1 discloses a needle for an endoscope with an outer sheath comprising a fluid channel, an excretion element arranged at the distal end of the outer sheath in such a way that it can be extended from the outer sheath and retracted into the inner sheath, and which is connected to the fluid channel. DE 10 2006 006 047 A1 discloses a treatment device for an endoscope with a flexible sheath, an actuating wire which is movable in the sheath in its longitudinal direction, and a treatment instrument arranged at a distal end of the actuating wire. The object of the invention is to provide a treatment instrument intended for endoscopes which is designed in such a way that it can stably maintain the desired extension length of a treatment element arranged at the distal end, and which has high usability at low manufacturing costs. The invention solves this problem through the subject matter of the independent claims. Advantageous embodiments are specified in the dependent claims. In the design according to claim 1, the extension length of the treatment element from the distal or anterior end of the flexible sheath can be permanently maintained at the desired length. This is achieved with a treatment instrument that can be manufactured at low cost and at the same time exhibits excellent usability. The further development according to claim 23 makes it possible to adjust the extension length of the treatment element to the desired length when the treatment instrument is inserted into an instrument channel of the endoscope. The treatment instrument according to this further development can be manufactured at low cost and at the same time exhibits excellent usability. The treatment instrument according to claim 34 also makes it possible to adjust the extension length of the treatment element to the desired length when the treatment instrument is inserted into an instrument channel of an endoscope. This treatment instrument can be manufactured at low cost and at the same time exhibits excellent usability. The invention is explained in more detail below with reference to the figures. These show: Fig. 1 a longitudinal section through a treatment instrument according to the first embodiment, showing the structure of the front end part of a flexible sheath; Fig. 2 a cross-section through the treatment instrument along line II-II shown in Fig. 1; Fig. 3 the overall structure of the treatment instrument according to the first embodiment; Fig. 4 a longitudinal section through the front end part of a flexible sheath according to the second embodiment; Fig. 5 a longitudinal section through the front end section of a flexible sheath according to the third embodiment; Fig. 6 a cross-section through the flexible sheath along line VI-VI shown in Fig. 5; Fig. 7 a longitudinal section through the front end part of a flexible sheath according to the fourth embodiment; Fig. 8 a state in which an actuating wire is fully inserted towards the front; Fig.Fig. 9 a state in which the actuating wire is completely retracted to the rear; Fig. 10 a longitudinal section through the front end part of a flexible sleeve according to the fifth embodiment; Fig. 11 a state in which the actuating wire is completely inserted to the front; Fig. 12 a state in which the actuating wire is completely retracted; Fig. 13 a perspective view of a flexible friction element according to the sixth embodiment in a state in which the friction element is arranged in a flexible sleeve; Fig. 14 a longitudinal section through the front end part of a flexible sleeve according to the seventh embodiment; Fig. 15 the overall structure of one of the treatment instruments according to the eighth embodiment; Fig. 16 a longitudinal section through the front end part of a treatment instrument according to the ninth embodiment; Fig.17 a perspective view of a treatment element and an actuating wire arranged in the treatment instrument shown in Fig. 16; Fig. 18 a cross-section through the treatment instrument along line XVIII-XVIII shown in Fig. 16; Fig. 19 a longitudinal section through the front end part of a flexible sheath according to the ninth embodiment to illustrate a state in which a treatment element is actuated; Fig. 20 the overall structure of the treatment instrument according to the ninth embodiment; Fig. 21 a longitudinal sectional view of the treatment instrument according to the ninth embodiment to illustrate the internal structure of an actuating unit of the treatment instrument; Fig. 22 a cross-section through the front end part of a flexible sheath according to the tenth embodiment; Fig.Fig. 23 shows a longitudinal section through a treatment instrument according to the eleventh embodiment to illustrate the internal structure of the front end part of a flexible sheath; Fig. 24 shows a longitudinal section of a treatment instrument according to the twelfth embodiment to illustrate the internal structure of the front end part of a flexible sheath; Fig. 25 shows a longitudinal section through a treatment instrument according to the thirteenth embodiment to illustrate the internal structure of the front end part of a flexible sheath; Fig. 26 shows a cross-section through the treatment instrument along line XXVI-XXVI shown in Fig. 25; and Fig. 27 shows a longitudinal section through a treatment instrument according to the fourteenth embodiment to illustrate the internal structure of the front end part of a flexible sheath. Description of exemplary implementations The following are examples of implementation described with reference to the figures. FIRST IMPLEMENTATION EXAMPLE Fig. 3 shows the overall structure of a treatment instrument 100 intended for endoscopes according to a first embodiment. The treatment instrument 100 has a flexible sheath 1, which is formed from a flexible tube, e.g., a tube made of tetrafluoroethylene resin, and an actuating wire 2, which consists of a strand of wire formed from twisted, conductive stainless steel wires. The actuating wire 2 is elongated in the longitudinal direction of the treatment instrument 100 and is movable in the longitudinal direction. The treatment instrument 100 is inserted into an instrument channel of an endoscope. At the front end of the flexible sheath 1 is a treatment element 3. The treatment element 3 is a thin, rod-shaped element. It is conductive and functions as a high-frequency electrode. The treatment element 3 is connected to the leading or distal end of the actuating wire 2, so that it can be extended from and retracted into the front end of the sheath 1 by moving the actuating wire 2. The treatment instrument 100 has an operating unit 10. The operating unit 10 comprises a fixed hook 12 and a movable hook 13. The fixed hook 12 is formed at the rear end of the operating body 11, which is connected to the proximal end of the flexible sheath 1. The movable hook 13 is mounted on the operating body 11 so that it is slidable in the longitudinal direction of the operating body 11. The movable hook 13 is connected to the proximal end of the actuating wire 2. A terminal 14 is located on the movable hook 13, to which a cable of a high-frequency power supply can be connected. The treatment element 3, located at the front end, is supplied with high-frequency voltage via the terminal 14 and the actuating wire 2. When the movable hook 13 is moved along the operating body 11, as indicated by the double arrow A in Fig. 3, the actuating wire 2 moves longitudinally within the flexible sheath 1. The treatment element 3 also moves longitudinally at the front end of the sheath 1, as shown by the double arrow B in Fig. 3. This design allows adjustment of the extension or cantilever length by which the treatment element 3 projects from the front end of the sheath 1. As shown in Fig. 3, the treatment instrument 100 has a flexible friction element 4 at the front or distal end of the flexible sheath 1. This friction element 4 serves to maintain the desired extension length of the treatment element 3. Fig. 1 is a longitudinal section through the treatment instrument 100, showing the structure of the front end part of the flexible sheath 1. The actuating wire 2 is a strand of wire consisting of several twisted wires. The treatment element 3 is formed by extending one of the wires forming the actuating wire 2, e.g., a core wire, longitudinally. This allows the treatment element 3 to connect seamlessly to the actuating wire 2. Fig. 2 shows a cross-section through the treatment instrument 100 along line II-II shown in Fig. 1. The friction element 4 is a flexible, tubular element. As shown in Fig. 1, this flexible friction element 4 is pressed into the front end part of the flexible sleeve 1, so that, in the state shown in Fig. 2, it is compressed by the outer surface of the actuating wire 2 and the inner surface of the sleeve 1 and has a concave section in which the friction element 4 is elastically deformed by the outer surface of the actuating wire 2. Since the friction element 4 is simply pressed into the flexible sleeve 1, it is not fixed relative to the sleeve 1. This design helps to reduce manufacturing costs. The flexible friction element 4 consists, for example, of a tetrafluoroethylene resin tube whose outer diameter is smaller than the inner diameter of the flexible sleeve 1 and whose thickness is smaller than that of the sleeve 1. Although the material, e.g., the tetrafluoroethylene resin tube from which the friction element 4 is made, does not exhibit particularly high elasticity, the indented section in which the tetrafluoroethylene resin tube is elastically deformed exerts a strong restoring force that tends to return the indented section to its original, i.e., cylindrical, shape. This strong restoring force acts on the actuating wire 2 and the flexible sleeve 1. The contact area where the flexible friction element 4 contacts the inner surface of the flexible sleeve 1 is larger than the contact area where the friction element 4 contacts the outer surface of the actuating wire. When the actuating wire 2 is moved longitudinally within the sleeve 1, this ensures that only the actuating wire 2 moves longitudinally, while the friction element 4 remains fixed longitudinally as long as it does not become entangled with the actuating wire 2. Thus, when the actuating wire 2 is moved longitudinally within the flexible sleeve 1, the friction occurring between the actuating wire 2 and the flexible friction element 4, as well as the friction occurring between the actuating wire 2 and the inner surface of the sleeve 1, influence the movement of the actuating wire 2. However, it is still possible that the friction element 4 becomes entangled with the actuating wire 2 and is thus moved within the flexible sheath 1 when the actuating wire 2 is moved. In this case, the friction occurring between the inner surface of the flexible sheath 1 and the actuating wire 2, and the friction occurring between the friction element 4 and the inner surface of the sheath 1, affect the movement of the actuating wire. The friction acting on the longitudinal movement of the actuating wire 2 is proportional to the restoring force generated in the concave section of the friction element 4, which tends to return the concave section to its original shape. This design ensures that the actuation of the movable hook 13, which moves the actuating wire 2, feels to the user both slippery and, to a certain degree, resistant. Actuation of the movable hook 13 thus gives the user the sensation that the actuating wire 2 is being pressed against the smooth surface of the tetrafluoroethylene resin tube. With the construction described above, it is possible to adjust the extension length of the treatment element 3 within the length range L shown in Fig. 1. The user is thus able to adjust the extension length of the treatment element 3 to a desired length, depending on the purpose of the treatment instrument 100. As described above, the set extension length of the treatment element 3 remains stable. In particular, the extension length is not changed by an external force exerted when the treatment element 3 touches the tissue of a body cavity during a diagnostic procedure. This is ensured by the friction exerted on the actuating wire 2 by the flexible friction element 4. In this embodiment, the treatment instrument 100 is designed such that the tip, i.e., the distal end of the treatment element 3, is completely retracted into the front end of the flexible sheath 1 when the actuating wire 2, i.e., the movable hook 13, is fully retracted to the rear. In this state, the distal end of the treatment element 3 does not protrude from the front end of the sheath 1. However, it is also possible that the distal end of the treatment element 3 protrudes slightly from the front end of the sheath 1 when the movable hook 13 is fully retracted. The strength of the frictional force acting on the movement of the actuating wire 2 is essentially proportional to the length of the flexible friction element 4. Therefore, the strength of the frictional force acting on the movement of the actuating wire 2 can be adjusted to a desired value by appropriately adjusting the length of the friction element 4 during the manufacturing process, depending on the intended use of the treatment instrument 100 or on the required specifications that the treatment instrument 100 is to meet. In this embodiment, the friction element 4 can also be replaced by a new element, since it is not attached to the inner surface of the flexible sheath 1. As shown in Fig. 1, a stop can be provided at the front end of the sleeve 1 to prevent the flexible friction element 4 from detaching from the front end of the flexible sleeve 1. The stop 5 is, for example, a rod-shaped element made of polyetheretherketone resin (PEEK) and can be pressed into the flexible sleeve 1. The stop 5 has a longitudinally extending through-hole that the treatment element 3 passes through in a smooth motion. In the construction described above, the treatment element 3 can be extended longitudinally from the front end of the casing 1. The forward movement of the treatment element 3 is stopped when the front edge of the actuating wire 2 touches the rear end of the stop 5. The maximum extension length of the treatment element 3 is therefore limited by the rear end of the stop 5. When the actuating wire 2 is inserted, the flexible friction element 4 moves towards the front end of the sleeve 1. Its movement is stopped when it touches the rear end of the stop 5. This prevents the friction element 4 from disengaging from the front end of the sleeve 1. SECOND EXAMPLE A second embodiment of the treatment instrument is described below. Since the second embodiment is a modification of the first, only those features that distinguish it from the first are described below. In the figures relating to the second embodiment, those elements corresponding to those of the first embodiment are labeled with the reference numerals used in the first embodiment. These elements are not described again below. Fig. 4 shows a longitudinal section through the front end part of the flexible sleeve 1 for the second embodiment. In this embodiment, a tapered section 5B is formed at the front end of the flexible sleeve 1 instead of a separate stop (stop 5) located in the front end of the sleeve 1. For example, this tapered section 5B can be produced by reducing the diameter of the front end of the flexible sleeve 1 by hot forming. THIRD EXAMPLE The following describes a treatment instrument as a third embodiment. Since the third embodiment is a modification of the first embodiment, only those features that distinguish the third embodiment from the first will be described below. In the figures relating to the third embodiment, those elements that are essentially the same as those of the first embodiment are labeled with the reference numerals used in the first embodiment. These elements will not be described again below. Fig. 5 is a longitudinal section through the front end part of the flexible sleeve 1 according to the third embodiment. Fig. 6 is a cross-section through the flexible sleeve 1 along line VI-VI shown in Fig. 5. In this embodiment, a solid, rod-shaped element 4B, which exhibits elasticity, is used as a flexible friction element, achieving the same functions as the friction element 4 provided in the first embodiment. The flexible friction element 4B consists, for example, of silicone resin or silicone rubber. FOURTH EXAMPLE OF EXECUTION The following describes a treatment instrument as a fourth embodiment. Since the fourth embodiment is a modification of the first embodiment, only those features that distinguish the fourth embodiment from the first embodiment are described below. In the figures relating to the fourth embodiment, those elements that are essentially the same as those of the first embodiment are provided with the reference numerals used in the first embodiment. These elements will not be described again below. Fig. 7 is a longitudinal section through the front end portion of the flexible sleeve 1 according to the fourth embodiment. In this embodiment, a stop 6 is provided in the flexible sleeve 1 instead of the stop 5, arranged at the front end of the actuating wire 2. Similar to the stop 5, the stop 6 prevents the flexible friction element 4 from detaching from the front end of the flexible sleeve 1. The stop 6 is a tubular element attached to the leading or distal end of the actuating wire 2. For example, the stop 6 is made of a metal or a rigid plastic. The stop 6 has an outer diameter that is smaller than the inner diameter of the flexible sleeve 1. The stop 6 is attached to the distal end of the actuating wire 2, for example, by a soldered connection, an adhesive bond, or a crimp connection. Fig. 8 shows a situation in which the actuating wire 2 is fully inserted in the forward direction. The length of the actuating wire 2 is adjusted such that the stop 6 does not protrude from the front end of the sleeve 1 when the actuating wire 2 is fully inserted in the forward direction. This prevents the flexible friction element 4 from disengaging from the front end of the sleeve 1. If the friction element 4 moves towards the front end of the sleeve 1, this movement of the friction element 4 is stopped by the stop 6. Fig. 9 shows a situation in which the actuating wire 2 is fully retracted to the rear. In this situation, the treatment element 3 is also fully retracted into the front end of the sheath 1. However, since the stop 6 is attached to the distal end of the actuating wire 2, the flexible friction element 4 cannot be positioned at a location on the distal side of the stop 6, i.e., in front of it. FIFTH EXAMPLE The following describes a treatment instrument as a fifth embodiment. Since the fifth embodiment is a modification of the fourth embodiment, only those features that distinguish the fifth embodiment from the fourth will be described below. In the figures relating to the fifth embodiment, those elements that are essentially the same as those of the fourth embodiment are labeled with the reference numerals used in the fourth embodiment. These elements will not be described again below. Fig. 10 is a longitudinal section through the front end portion of the flexible sleeve 1 according to the fifth embodiment. In this embodiment, a rear stop 7 is additionally provided. The rear stop 7 serves to limit the backward movement of the flexible friction element 4. The stop 7 is a tubular element and is attached to the actuating wire 2 behind the friction element 4. The rear stop 7 is made, for example, of a metal or a rigid plastic. The outer diameter of the rear stop 7 is smaller than the inner diameter of the sleeve 1. The stop 7 is attached to the actuating wire 2, for example, by a soldered connection, an adhesive bond, or a precision fit. Fig. 11 shows a situation in which the actuating wire 2 is fully inserted in the forward direction. The length of the actuating wire 2 is adjusted such that the front stop 6 does not protrude from the front end of the flexible sleeve 1 when the actuating wire 2 is fully inserted forward. This prevents the friction element 4 from disengaging from the front end of the flexible sleeve 1. If the friction element 4 moves towards the front end of the sleeve 1, this forward movement of the friction element 4 is limited by the front stop 6. The backward movement of the friction element 4 is limited by the rear stop 7 in such a way that the friction element 4 cannot be positioned behind the rear stop 7. Fig. 12 shows a situation in which the actuating wire 2 is fully retracted. In this situation, the treatment element 3 is fully retracted into the front end of the sleeve 1. However, since the front stop 6 is attached to the distal end of the actuating wire 2, the friction element 4 cannot be positioned in front of the front stop 6. Furthermore, since the rear stop 7 is located behind the friction element 4, the friction element 4 cannot be located behind the stop 7. SIXTH EXAMPLE OF EXECUTION The following describes a treatment instrument as a sixth embodiment. Since the sixth embodiment is a modification of the first embodiment, only those features that distinguish the sixth embodiment from the first will be described below. In the figures relating to the sixth embodiment, those elements that are essentially the same as those of the first embodiment are labeled with the reference numerals used in the first embodiment. These elements will not be described again below. In this embodiment, a flexible friction element 4C is used instead of the flexible friction element 4. Fig. 13 shows the external appearance of this flexible friction element 4C in a state where the friction element 4C is arranged in the casing 1. The flexible casing 1 has been omitted in Fig. 13 to clarify the external appearance of the friction element 4C. As indicated by reference numeral 8 in Fig. 13, the flexible friction element 4C undergoes a surface treatment to increase the frictional resistance on the part of the surface that is not in contact with the actuating wire 2, i.e., on the part of the surface that is in contact with the inner surface of the flexible sleeve 1. Such a surface treatment is obtained, for example, by chemically treating said part of the surface of the friction element 4C with a strong acid. This design ensures that the flexible friction element 4C moves less in the longitudinal direction relative to the flexible sleeve 1. Therefore, in the sixth embodiment, the stops 5, 6 and 7 can be omitted. SEVENTH EXAMPLE OF EXECUTION The following describes a treatment instrument as the seventh embodiment. Since the seventh embodiment corresponds to a modification of the first embodiment, only those features that distinguish the seventh embodiment from the first embodiment are described below. In the figures relating to the seventh embodiment, those elements of the seventh embodiment that are essentially the same as those of the first embodiment are labeled with the reference numerals used in the first embodiment. These elements are not described again below. Fig. 14 is a longitudinal section through the front end part of the flexible sleeve 1 according to the seventh embodiment. In this embodiment, instead of the friction element 4, a flexible friction element 4D, formed by a rubber O-ring, is located in the flexible sleeve 1. In this embodiment, the friction element that generates the friction acting on the movement of the actuating wire 2 consists of a flexible ring-shaped element. EIGHTH EXAMPLE OF EXECUTION The following describes a treatment instrument as the eighth embodiment. Since the eighth embodiment is a modification of the first embodiment, only those features that distinguish it from the first will be described below. In the figures relating to the third embodiment, those features that are essentially the same as those of the first embodiment are marked with the reference numerals used in the first embodiment. These features will not be described again below. Fig. 15 shows the overall structure of a treatment instrument 101 according to the eighth embodiment. In this embodiment, two or more flexible friction elements 4 are provided in the flexible sleeve 1, as shown in Fig. 15. These friction elements 4 are pressed into the flexible sleeve 1. The friction elements 4 can differ from one another in size or material. NINTH EXAMPLE The following embodiments (ninth to fourteenth embodiments) serve to enable, in the simplest possible way, a fine adjustment of the extension length of the treatment instrument from the front end of the flexible sheath. Fig. 20 shows the overall structure of a treatment instrument 200 intended for endoscopes according to the ninth embodiment. In the following figures, those elements that are essentially the same as those of the first embodiment are provided with the reference numerals used in the first embodiment. The treatment instrument 200 has a flexible sheath 1, consisting of a flexible tube, e.g., a tetrafluoroethylene resin tube, and an actuating wire 2B. The actuating wire 2B is formed from a strand of wire consisting of twisted, conductive stainless steel wires. The actuating wire 2B is elongated along the length of the treatment instrument 200 and is movable in this direction. The treatment instrument 200 is inserted into an instrument channel of an endoscope. The treatment element 3 is located at the front end of the flexible sheath 1. The treatment element 3 is a thin, rod-shaped element that is conductive and functions as a high-frequency electrode. The treatment element 3 is integrally formed with the leading or distal end of the actuating wire 2B, so that the treatment element 3 can be extended from and retracted into the front end of the sheath 1 by moving the actuating wire 2B. The treatment element 3 is also rotatable about its longitudinal axis. Thus, it is rotated when the distal end of the actuating wire 2B is turned. The treatment instrument 200 has a control unit 20 in which a fixed hook 22 is formed at the rear end of a control body 21, which is connected to the proximal end 2a of the actuating wire 2B. A movable hook 23 is mounted on the control body 21 in the control unit 20 such that it can be moved along the control body 21. A terminal 24 is located on the movable hook 23. When a cable of a high-frequency power supply is connected to the terminal 24, the treatment element 3 is supplied with a high-frequency voltage via the actuating wire 2B. In a diagnostic procedure, the tissue of a body cavity can thus be subjected to high-frequency treatment. At the proximal end of the flexible sheath 1 is an adjustment knob 30. Fig. 21 shows a partially cutaway longitudinal view of the treatment instrument 200, illustrating the internal structure of the control unit 20. As shown in Fig. 21, a pin base 11 is coupled to a bearing hole 21a formed in the front end of the control body 21 such that it is rotatable about its longitudinal axis. The adjustment knob 30 is attached to the front part of the pin base 11. A slot 26 is formed in the control body 21, which receives the movable hook 23 so as to be slidably positioned in the longitudinal direction. By moving the hook 23 longitudinally, as indicated by the double arrow A in Fig. 20, the actuating wire 2B moves longitudinally within the sheath 1, thereby extending or retracting the treatment element 3 from the front end of the sheath 1, as indicated by the double arrow B in Fig. 20. By holding the adjustment knob 30 with the fingers, as shown in Fig. 20, and rotating the control unit 20 as a whole about its longitudinal axis, the actuating wire 2B rotates within the flexible sheath 1 about its longitudinal axis, which also causes the treatment element 3 at the front end of the sheath 1 to rotate about its longitudinal axis. As a result, the treatment element 3 moves a short distance longitudinally in a spiral motion. Fig. 16 is a longitudinal section through the front end part of the treatment instrument 200. Fig. 17 shows a perspective view of the treatment element 3 and the actuating wire 2B. As can be seen from Fig. 17, the treatment element 3 can be manufactured by making one of the twisted wires forming the actuating wire 2B, e.g., a core wire, longer than the other wires (e.g., by stretching). The treatment element 3 thus connects seamlessly to the actuating wire 2B. In this embodiment, the actuating wire 2B is manufactured by twisting seven stainless steel wires together. This creates a so-called 1x7 wire strand. Alternatively, the actuating wire 2 can be manufactured from a torsionally stiff, twisted wire. Fig. 18 is a cross-section through the treatment instrument 200 along line XXVIII-XXVIII shown in Fig. 16. The flexible friction element 4 is a tubular element. As shown in Fig. 16, the flexible friction element 4 is pressed into the front end part of the flexible sleeve 1, so that in the state shown in Fig. 18 it is compressed by the outer surface of the actuating wire 2B and the inner surface of the sleeve 1 and has a concave section in which the friction element 4 is elastically deformed by the outer surface of the actuating wire 2B. Since the flexible friction element 4 is simply pressed into the flexible sleeve 1, it is not fixed relative to the sleeve 1. This design contributes to reducing manufacturing costs. When the control unit 20 is actuated in this design to rotate the actuating wire 2B, as indicated by arrow C in Fig. 19, the actuating wire 2B rotates about its longitudinal axis. Since, in this case, the friction element 4 is pressed against the outer surface of the actuating wire 2B while the actuating wire 2B is engaged with it, the treatment element 3 rotates about its longitudinal axis and moves longitudinally. As indicated by arrow B in Figs. 19 and 20, the treatment element 3 moves in a spiral motion. In this way, the extension length by which the treatment element 3 protrudes from the front end of the casing 1 can be finely adjusted. Such fine adjustment of the extension length of the treatment element 3 is achieved by the actuating wire 2B being engaged with the friction element 4 while the friction element 4 is pressed against the actuating wire 2B. This fine adjustment is also based on the fact that the contact area over which the actuating wire 2B contacts the friction element 4 is smaller than the contact area over which the friction element 4 contacts the inner surface of the flexible sleeve 1. Thus, the friction generated between the friction element 4 and the sleeve 1 is greater than the friction generated between the friction element 4 and the actuating wire 2B. As described above, in this embodiment the extension length of the treatment element 3 can be finely adjusted in a situation where the treatment instrument 200 is inserted into an instrument channel of an endoscope. The advantages described for the embodiment above can also be achieved by simply using a twisted wire (which does not have the special configuration provided in the embodiment) as the actuating wire 2B and simply pressing the flexible friction element 4 into the flexible sleeve 1. It is also possible, in a first step, to move the movable hook 23 in the longitudinal direction for the purpose of a coarse adjustment of the extension length of the treatment element 3 and, in a second step, to rotate the control unit 20 for the purpose of a fine adjustment of the extension length of the treatment element 3. If the control unit 20 is not actuated, the actuating wire 2B is held in position by the friction generated between it and the flexible friction element 4. The extension length of the treatment element 3 is therefore not changed by an external force that occurs when the treatment element 3 touches the tissue of a body cavity during a diagnostic operation. The extension length of the treatment element 3 can thus be kept stable at the desired value. Similar to the first embodiment, a stop 5 is arranged at the front end of the flexible sleeve 1. The stop 5 serves to define the maximum extension length of the treatment element 3. The treatment element 3 penetrates the through-hole formed in the stop 5 along its longitudinal axis and thus moves smoothly through the through-hole of the stop 5. The stop 5 prevents the flexible friction element 4 from detaching from the front end of the sleeve 1. Similar to the second embodiment, the flexible sleeve 1 can have a narrowed or tapered section at its front end, which takes over the function of the stop 5 (see Fig. 4). TENTH EXAMPLE OF EXECUTION The following describes a treatment instrument as the tenth embodiment. Since the tenth embodiment corresponds to a modification of the ninth embodiment, only those features that distinguish the tenth embodiment from the ninth embodiment are described below. In the figures relating to the tenth embodiment, those elements that are essentially the same as those of the ninth embodiment are labeled with the reference numerals used in the ninth embodiment. These elements are not described again below. Fig. 22 is a cross-section through the front end part of the flexible sleeve 1 according to the tenth embodiment. In this embodiment, a solid, rod-shaped element 4B, which exhibits elasticity, is used to achieve the function that the flexible friction element 4 has in the ninth embodiment. For example, the flexible friction element 4B used in this embodiment consists of silicone resin or silicone rubber. ELEVENTH EXAMPLE OF EXECUTION The following describes a treatment instrument as the eleventh embodiment. Since the eleventh embodiment corresponds to a modification of the ninth embodiment, only those features that distinguish the eleventh embodiment from the ninth embodiment are described below. In the figures relating to the eleventh embodiment, those elements that are essentially the same as those of the ninth embodiment are labeled with the reference numerals used in the ninth embodiment. These elements are not described again below. Fig. 23 is a longitudinal section through the treatment instrument according to the eleventh embodiment and shows the structure within the front end part of the flexible sheath 1. In this embodiment, a flexible friction element 4E, which has a cylindrical shape, is used instead of the friction element 4. Since the flexible friction element 4E is elastically designed, the inner surface of the friction element 4E deforms when the outer surface of the actuating wire 2B presses against it, as shown in Fig. 23. In this embodiment, the flexible friction element 4E is not attached to the inner surface of the flexible sleeve 1. However, it can also be attached to the inner surface of the sleeve 1. By attaching the flexible friction element 4E to the inner surface of the sleeve 1, it is possible to prevent the friction element 4E from moving together with the actuating wire 2B. The eleventh embodiment achieves the same advantages as the ninth embodiment. TWELVE EXECUTION EXAMPLE The following describes a treatment instrument as the twelfth embodiment. Since the twelfth embodiment is a modification of the ninth embodiment, only those features that distinguish the twelfth embodiment from the ninth embodiment are described below. In the figures relating to the twelfth embodiment, those elements that are essentially the same as those of the ninth embodiment are labeled with the reference numerals used in the ninth embodiment. These elements are not described again below. Fig. 24 is a longitudinal section through the treatment instrument according to the twelfth embodiment and shows the structure in the front end part of the flexible sleeve 1. In this embodiment, inwardly recessed sections 15 are formed by bending the flexible sleeve 1 at corresponding points so that it curves inwards at these points. The inwardly recessed sections 15 serve to limit the longitudinal movement of the flexible friction element 4. The twelfth embodiment achieves the same advantages as the ninth embodiment. THIRTEENTH EXAMPLE OF EXECUTION The following describes a treatment instrument as a thirteenth embodiment. Since the thirteenth embodiment is a modification of the ninth embodiment, only those features that distinguish the thirteenth embodiment from the ninth embodiment are described below. In the figures relating to the thirteenth embodiment, those elements that are essentially the same as those of the ninth embodiment are labeled with the reference numerals used in the ninth embodiment. These elements are not described again below. Fig. 25 is a longitudinal section through the treatment instrument according to the thirteenth embodiment and shows the structure in the front end part of the flexible sheath 1. In this embodiment, the actuating wire 2B comprises a first wire strand section 2' and a second wire strand section 2", which are connected to each other in rows. The first wire strand section 2' is formed at the front end section where the actuating wire 2B is pressed against the friction element 4. The first wire strand section 2' consists of wires that are twisted together such that the twist pitch is different from that of the second wire strand section 2"". For example, the twist pitch of the first wire strand section 2' is greater than that of the second wire strand section 2"". The two wire strand sections 2' and 2" are coupled to each other via a connecting tube 9. Fig. 26 is a cross-section through the treatment instrument along line XXVI-XXVI shown in Fig. 25. As shown in Fig. 26, the first wire strand 2' consists of three wires twisted together, thus forming a so-called 1x3 wire strand. Each of the wires forming the first wire strand 2' has a diameter larger than the diameter of the individual wires forming the second wire strand 2" By forming the wire strand 2B as described above, the longitudinal movement distance of the treatment element 3 can be increased with respect to the rotation angle of the actuating wire 2B. The second wire strand section 2" can also be made of a torsion-resistant wire. In this case, the follow-up or response capability of the first wire strand section 2' with respect to the rotational movement of the control unit 20 can be increased. If the actuating wire 2B were entirely composed of wires as thick as those used in the first stranded wire section 2', the actuating wire 2B might tend to bend in a certain direction. Therefore, in this embodiment, only the front end section of the actuating wire 2B is formed from relatively thick wires. FOURTEENTH EXAMPLE The following describes a treatment instrument as a fourteenth embodiment. Since the fourteenth embodiment corresponds to a modification of the thirteenth embodiment, only those features that distinguish the fourteenth embodiment from the thirteenth embodiment are described below. In the figures relating to the fourteenth embodiment, those elements that are essentially the same as those of the thirteenth embodiment are labeled with the reference numerals used in the thirteenth embodiment. These elements are not described again below. Fig. 27 is a longitudinal section through the treatment instrument according to the fourteenth embodiment and shows the structure at the front end of the flexible sheath 1. In this embodiment, two connecting tubes 9B, 9C are provided at the front and rear ends of the first wire strand section 2'. The front end of the first wire strand section 2' is connected to the treatment element 3 via the connecting tube 9B, and the rear end of the first wire strand section 2' is connected to the second wire strand section 2" via the connecting tube 9C. The above-described examples can be modified. For example, the flexible friction element can be modified in shape and size depending on the intended use of the treatment instrument. The above-described designs of the treatment instrument can also be applied to an instrument in which the treatment element located at the front end is not supplied with a high-frequency current.

Claims

Treatment instrument (100) for an endoscope, comprising: - a sheath (1) which consists at least partly of a flexible tube; - an actuating wire (2) which is inserted into the sheath (1) and is movable in the longitudinal direction of the sheath; and - a treatment element (3) which is connected to the distal end of the actuating wire (2) and which can be extended from and retracted into the distal end of the sheath (1) by moving the actuating wire (2); - characterized by at least one elastic element (4) which is arranged in the distal end part of the sheath (1) such that it is elastically deformed between the inner surface of the sheath (1) and the outer surface of the actuating wire (2). Treatment instrument (100) according to claim 1, characterized in that: - the friction generated between the sheath (1), the actuating wire (2) and the elastic element (4) acts on the longitudinal movement of the actuating wire (2); and - the extension length of the treatment element (3) from the distal end of the sheath (1) is adjustable by moving the actuating wire (2) in the longitudinal direction. Treatment instrument (100) according to claim 1 or 2, characterized in that the treatment element (3) is a high-frequency electrode; and the actuating wire (2) is conductive and is electrically connected to the treatment element (3). Treatment instrument (100) according to one of the preceding claims, characterized in that - the actuating wire (2) consists of several wires twisted together; and - one of the wires forming the actuating wire (2) is extended distally relative to the other wires and the distally extended part of this wire forms the treatment element (3). Treatment instrument (100) according to one of the preceding claims, characterized in that the elastic element (4) is arranged in the distal end part of the shell (1) without being fixedly attached to the inner surface of the shell (1). Treatment instrument (100) according to one of the preceding claims, characterized in that the elastic element (4) is a tubular element. Treatment instrument (100) according to claim 6, characterized in that the outer diameter of the tubular element is smaller than the inner diameter of the casing (1). Treatment instrument (100) according to one of claims 1 to 5, characterized in that the elastic element (4B) is a solid, rod-shaped element. Treatment instrument (100) according to one of claims 1 to 5, characterized in that the elastic element (4D) is an annular element that surrounds the actuating wire (2) in the distal end part of the sheath (1). Treatment instrument (100) according to one of the preceding claims, characterized by a distal stop (5) arranged in the flexible sheath (1) which prevents the elastic element (4) from detaching from the distal end of the sheath (1). Treatment instrument (100) according to claim 10, characterized in that the distal stop (5) is arranged at the distal end of the sheath (1). Treatment instrument (100) according to claim 11, characterized in that the distal stop (5) is attached to the distal end of the sheath (1). Treatment instrument (100) according to claim 11, characterized in that a tapered section (5B) is formed by a tapering of the distal end of the sheath (1). Treatment instrument (100) according to claim 10, characterized in that a stop (6) is attached to the actuating wire (2). Treatment instrument (100) according to claim 14, characterized in that the stop (6) is a tubular element whose outer diameter is smaller than the inner diameter of the casing (1). Treatment instrument (100) according to claim 14, characterized in that the stop (6) is attached to the actuating wire (2) in such a way that it does not protrude from the distal end of the sheath (1) when the actuating wire (2) is moved to a distal endpoint of a range of motion within which the actuating wire (2) is movable in the longitudinal direction. Treatment instrument (100) according to one of the preceding claims, characterized by a proximal stop (7) which is arranged in the shell (1) in such a way that it limits the movement of the elastic element (4) in the proximal direction. Treatment instrument (100) according to claim 17, characterized in that the proximal stop (7) is attached to the actuating wire (2). Treatment instrument (100) according to claim 18, characterized in that the proximal stop (7) is a tubular element whose outer diameter is smaller than the inner diameter of the casing (1). Treatment instrument (100) according to one of the preceding claims, characterized in that the elastic element (4C) has a surface (8) which is surface-treated in such a way that the friction between this surface (8) and the inner surface of the casing (1) is increased, wherein the surface-treated surface (8) faces the inner surface of the casing (1) and is turned away from the outer surface of the actuating wire (2). Treatment instrument (100) according to one of the preceding claims, characterized in that the at least one elastic element comprises several elastic elements (4) which are each arranged in the distal end part of the sheath (1) and are elastically deformed between the inner surface of the sheath (1) and the outer surface of the actuating wire (2). Treatment instrument (100) according to one of the preceding claims, characterized in that the elastic element (4) is pressed into the distal end part of the sheath (1). Treatment instrument (101) according to one of the preceding claims, characterized by: - ​​an operating unit (10) arranged on a proximal end part of the sheath (1) and connected to the proximal end of the actuating wire (2B), whereby the actuating wire (2B) can be rotated about its longitudinal axis by actuating the operating unit (10), wherein: - at least one distal end part of the actuating wire (2B) is designed as a strand of wire consisting of several wires twisted together; and: - the treatment element (3) is moved longitudinally by pressing the distal end part of the actuating wire (2B) against the elastic element (4) when it rotates about the longitudinal axis by rotating the actuating wire (2B); and: - the extension length of the treatment element (3) from the distal end of the sheath (1) can be adjusted by means of the operating unit (10) by rotating the actuating wire (2B). Treatment instrument (101) according to claim 23, characterized in that the actuating wire (2B) as a whole consists of several wires twisted together. Treatment instrument (101) according to claim 23 or 24, characterized in that: - the actuating wire (2B) comprises a first wire strand part (2') and a second wire strand part (2") which have different twist pitch heights and are connected together in series; - the first wire strand part (2') is arranged on the distal end section of the actuating wire (2B) such that it is pressed against the elastic element (4); and - the second wire strand part (2") is arranged proximal to the first wire strand part (2'). Treatment instrument (101) according to claim 25, characterized in that the twisting height of the first wire strand part (2') is greater than that of the second wire strand part (2"). Treatment instrument (101) according to claim 25, characterized in that the second wire strand part (2") is formed from a torsionally stiff wire. Treatment instrument (101) according to one of claims 23 to 27, characterized by the distal stop (5) which is arranged in the sheath (1) in such a way that it limits the movement of the elastic element (4) and prevents the elastic element (4) from moving to a point where the distal end section of the actuating wire (2B) comes out of engagement with the elastic element (4). Treatment instrument (101) according to claim 28, characterized in that the distal stop (5) has a surface (8) which is part of the surface of the elastic element (4C) and is surface-treated; and the surface-treated surface (8) is arranged in contact with the inner surface of the sheath (1) and without contact with the outer surface of the actuating wire (2B). Treatment instrument (101) according to claim 23, characterized in that the control unit (10) comprises: - a first control unit (23) for rotating the actuating wire (2B) about the longitudinal axis; and - a second control unit (22) for moving the actuating wire (2B) in the longitudinal direction. Treatment instrument (101) for an endoscope, comprising: - a sheath (1) formed at least partially from a flexible tube; - an actuating wire (2B) inserted longitudinally into the sheath (1) for movement; - an operating unit (10) arranged at a proximal end part of the sheath (1) and connected to the proximal end of the actuating wire (2B), whereby the actuating wire (2B) is rotatable about its longitudinal axis when the operating unit (10) is actuated; - a treatment element (3) connected to the distal end of the actuating wire (2B); and - at least one elastic element (4) arranged in a distal end part of the sheath (1) such that it is elastically deformed between the inner surface of the sheath (1) and the outer surface of the actuating wire (2B), wherein - at least one distal end section of the actuating wire (2B) is designed as a strand of wire consisting of several wires twisted together;- the treatment element (3) is moved longitudinally by pressing the distal end section of the actuating wire (2B) against the elastic element (4) when it is rotated about the longitudinal axis by turning the actuating wire (2B); and - the extension length of the treatment element (3) from the distal end of the sheath (1) is adjustable by turning the actuating wire (2B) using the control unit (10).

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