Treatment tool

A treatment tool includes an elongated shaft that has a bending mechanism at a distal end thereof; a bending operation part that is connected to a proximal-end side of the shaft in order to operate the bending mechanism; a connection sleeve that is provided at a connection section of the bending operation part where the bending operation part and the shaft are connected, and that rotatably holds the shaft; a rotation operation member that is provided at the proximal-end side of the shaft and that rotates the shaft; and a stopper member that can be made to slide outside the connection sleeve along a direction of a longitudinal axis of the shaft and that is engaged with both the rotation operation member and the connection sleeve at a specific position in a range of movement thereof, thereby locking rotation of the shaft with respect to the connection sleeve.

TECHNICAL FIELD

The disclosed embodiments relate to a treatment tool.

BACKGROUND

A treatment tool may include: an elongated shaft that has a bending mechanism at a distal-end section; a handle that is connected to the proximal end of the shaft; and a bending operation part and a rotation operation part that are provided between the shaft and the handle). The bending operation part is used to perform a bending operation on the bending mechanism of the shaft, and the rotation operation part is used to rotate the shaft with respect to the handle.

The rotation operation part may be provided between the bending operation part and the handle and be configured so as to rotate the bending operation part and the shaft together. However, when the shaft is twisted about its longitudinal axis in the body, this may cause a deviation between operation of the handle and a bending direction of the bending mechanism in an endoscopic image.

SUMMARY

In one aspect of the disclosed embodiments, a treatment tool includes: an elongated shaft that has a bending mechanism at a distal end thereof; a bending operation part that is connected to a proximal-end side of the shaft in order to operate the bending mechanism; a connection sleeve that is provided at a connection section of the bending operation part where the bending operation part and the shaft are connected, and that rotatably holds the shaft; a rotation operation member that is provided at the proximal-end side of the shaft and that rotates the shaft; and a stopper member that can be made to slide outside the connection sleeve along a direction of a longitudinal axis of the shaft and that is engaged with both the rotation operation member and the connection sleeve at a specific position in a range of movement thereof, thereby locking rotation of the shaft with respect to the connection sleeve.

The disclosed embodiments also include an operation method for a treatment tool that includes: an elongated shaft that has a bending mechanism at a distal end thereof; and a bending operation part that rotatably holds the shaft at a proximal-end side of the shaft in order to perform a bending operation on the bending mechanism. The method includes locking rotation of the shaft with respect to the bending operation part; inserting the shaft into a body of a patient; after inserting the shaft into the body of the patient, releasing the lock when a deviation occurs in the correspondence relationship between operation of the bending operation part and a bending direction of the bending mechanism due to twisting of the shaft; in a state in which the lock has been released, rotating the shaft, through operation of a rotation operation member that is provided on the shaft, with respect to the bending operation part, thereby adjusting the correspondence relationship between the operation of the bending operation part and the bending direction of the bending mechanism; and locking again the rotation of the shaft, the rotation being performed by the rotation operation member.

DETAILED DESCRIPTION OF EMBODIMENTS

Treatment tools1according to an embodiment of the disclosed embodiments will be described below with reference to the drawings.

As shown inFIGS. 1 and 2, each of the treatment tools1of this embodiment includes: an elongated shaft2that has a bending section (bending mechanism)7at a distal end and that is inserted into the body; an operation unit3that is connected to a proximal end of the shaft2and that is manually operated by an operator X; and wires4(seeFIG. 4) that connect the bending section7and the operation unit3by passing through the inside of the shaft2and with which the bending section7is bent in accordance with an operation performed on the operation unit3.

FIG. 1is a view showing the overall configuration of a surgical system that includes the treatment tools1of this embodiment. As shown inFIG. 1, the surgical system includes: an endoscope20that is operated by a scopist S; the treatment tools1, which are operated by the operator X; treatment-tool holders60that are fixed to a bed40on which a patient Y lies and that support the treatment tools1; and a display unit80that displays an endoscopic image to be observed by means of the endoscope20. The treatment-tool holders60are cylindrical members through which the shafts2are made to pass. The shafts2are inserted into the body of the patient Y via treatment-tool channels provided on the endoscope20or external channels attached to the endoscope20.FIG. 1shows an example case in which the endoscope20has the two treatment-tool channels, and the operator X operates the two treatment tools1with both hands. While observing end effectors provided at the distal ends of the shafts2by means of the endoscope20, the operator X can adjust the positions and the orientations of the end effectors through operation of the operation units3, which are disposed outside the body.

As shown inFIG. 2, each of the shafts2includes: an elongated flexible section5that has flexibility; a distal-end section6that is disposed at a position close to a distal end of the flexible section5; and the bending section7, which connects the flexible section5and the distal-end section6and which can be bent in a direction intersecting a longitudinal axis A of the flexible section5.

An end effector (for example, forceps or knife) used to treat living tissue is provided at the distal-end section6.

In the flexible section5, four wires4that respectively correspond to upper, lower, left, and right sides of the bending section7are disposed around the longitudinal axis A of the flexible section5at approximately equal intervals in the circumferential direction. The vertical direction and the horizontal direction of the bending section7are each perpendicular to the longitudinal axis A of the flexible section5and are perpendicular to each other. A distal-end section of each of the wires4is fixed to the bending section7at a position away from the longitudinal axis A in a direction intersecting the longitudinal axis A, and a proximal-end section of each of the wires4is fixed to a ball (to be described later) of the operation unit3. Each of the wires4can be advanced and retracted along the longitudinal axis A of the flexible section5, and the bending section7is bent such that the wire4that is retracted toward the proximal end is located radially inward.

The flexible section5includes a tubular inner sheath5a(SeeFIG. 4) and a tubular outer sheath5b(SeeFIG. 4) that covers an outer side of the inner sheath5a. The inner sheath5aand the outer sheath5beach have such flexibility as to allow twist deformation about the longitudinal axis A.

A distal-end section of the outer sheath5bis fixed to a proximal-end section of the bending section7, and a proximal-end section of the outer sheath5bis fixed to a distal-end section of a rotating shaft8(to be described later) of the operation unit3.

The inner sheath5ais a multi-lumen tube having at least four lumens penetrating in the longitudinal direction, and the wires4are inserted into the lumens on a one-to-one basis. A distal-end section of the inner sheath5ais fixed to the distal-end section of the outer sheath5b, and a proximal-end section of the inner sheath5ais drawn from the proximal end of the outer sheath5band is disposed further toward the proximal end than the rotating shaft8. Sections of the inner sheath5aother than the distal-end section are not fixed to the outer sheath5b, thus allowing twist deformation of the inner sheath5aabout the longitudinal axis A in the outer sheath5bindependently of the outer sheath5b.

As shown inFIGS. 3 and 4, the operation unit3includes: the rotating shaft8, which is hard and which extends coaxially with the flexible section5; an operation handle9that is disposed at the proximal-end side of the rotating shaft8and that is gripped by the operator X; a bending operation part (operation part)10that is provided between the rotating shaft8and the operation handle9and that is used to bend the bending section7; a rotation operation part11that is provided integrally with the rotating shaft8and that is used to rotate the shafts2and8; and a rotation lock part (lock mechanism)12that is used to lock the rotation of the rotation operation part11.

As shown inFIG. 4, the rotating shaft8has a through-hole penetrating along the longitudinal axis A. The proximal-end section of the outer sheath5bis inserted into the rotating shaft8. The inner sheath5a, which is drawn from the proximal end of the outer sheath5bin the rotating shaft8, is fixed with respect to a socket13(to be described later) of the bending operation part10, at a fixing part19that is located further toward the proximal end than the rotating shaft8.

The bending operation part10has a ball joint structure that includes the nearly spherical hollow socket13and the nearly spherical ball (operation member)14that is rotatably engaged inside the socket13.

The socket13has a shape obtained by cutting out a proximal-end side of a sphere, in a plane perpendicular to the longitudinal axis of the rotating shaft8, and is open at a proximal-end surface thereof. The ball14is supported on an inner surface of the socket13such that the center of the ball14matches the center of the socket13, and the ball14can be rotated in an arbitrary direction about the center, with respect to the socket13.

The operation handle9has a substantially straight rod shape, is connected to an outer surface of the ball14, the outer surface being exposed from the proximal-end surface of the socket13, and extends toward the opposite side from the shaft8and the socket13. The operation handle9is tilted in an arbitrary direction about the center of the socket13and the ball14through rotation of the ball14in the socket13.

The four wires4, which are drawn from the proximal end of the inner sheath5a, are routed between the inner surface of the socket13and an outer surface of the ball14. The proximal-end sections of the four wires4are fixed to the outer surface of the ball14at positions that are arranged at equal intervals in the circumferential direction around the longitudinal axis A.

The operator X tilts the operation handle9in a direction intersecting the longitudinal axis A to rotate the ball14inside the socket13, thereby making it possible to pull the wire4that corresponds to the tilt direction of the operation handle9, thus bending the bending section7. For example, when the operation handle9is tilted in the right direction, rotation (pivoting) of the ball14in the right direction pulls the left wire4and pushes the right wire4, thus bending the bending section7toward the left.

A cylindrical connection sleeve (rotation mechanism)15that extends toward the distal end (the shafts2and8) along the longitudinal axis A and into which the proximal-end section of the rotating shaft8is inserted so as to be rotatable about the longitudinal axis A is connected to the socket13. The rotating shaft8and the bending operation part10are held by the connection sleeve15so as to be rotatable relative to each other about the longitudinal axis A.

The rotation operation part11is a rotating handle that is fixed to the proximal-end section of the rotating shaft8and that is provided coaxially with the shafts2and8. The bending section7is rotated about the longitudinal axis through rotation of the rotation operation part11about the longitudinal axis A. Specifically, through rotation of the rotation operation part11, the rotating shaft8is rotated about the longitudinal axis A with respect to the bending operation part10and the operation handle9, and the proximal-end section of the outer sheath5b, which is connected to the rotating shaft8, is rotated about the longitudinal axis A. The outer sheath5bis twisted about the longitudinal axis A, thereby transmitting the rotation of the proximal-end section of the outer sheath5bto the distal-end section of the outer sheath5b. Then, the bending section7, which is fixed to the distal-end section of the outer sheath5b, is rotated about the longitudinal axis A.

At this time, although the distal-end section of the inner sheath5a, which is fixed to the distal-end section of the outer sheath5b, is rotated in accordance with the rotation of the rotation operation part11, the proximal-end section of the inner sheath5a, which is fixed with respect to the socket13at the fixing part19, which is located further toward the proximal end than the rotating shaft8, is not rotated. Therefore, the inner sheath5aand the wires4are twisted about the longitudinal axis A at a side further toward the distal end than the fixing part19, and the wires4are not twisted about the longitudinal axis A at a side further toward the proximal end than the fixing part19. Accordingly, in the bending operation part10, which is located further toward the proximal end than the fixing part19, the positions of the four wires4about the longitudinal axis A are maintained irrespective of the rotations of the shafts2and8.

As shown inFIGS. 5A and 5B, the rotation lock part12includes: a cylindrical stopper12athat is disposed outside the connection sleeve15and that locks and releases rotation of the rotation operation part11by being made to slide along the longitudinal axis A between a lock position (seeFIG. 5A) and a release position (seeFIG. 5B); and an engagement ring12bthat is provided on the rotation operation part11and that is engaged with locking protrusions12cthat are provided on an inner circumferential surface of the stopper12a, in the circumferential direction around the longitudinal axis A.

A pair of engagement protrusions12dthat are arranged with a space therebetween in the circumferential direction are provided on the inner circumferential surface of the stopper12a, and a guide protrusion15athat extends in the direction along the longitudinal axis A and that is fitted between the pair of engagement protrusions12dis provided on an outer circumferential surface of the connection sleeve15. Although the pair of engagement protrusions12dcan be moved along the guide protrusion15ain the direction along the longitudinal axis A, rotation thereof about the longitudinal axis A is locked by the guide protrusion15a. Accordingly, the stopper12ais mounted on the outer circumferential surface of the connection sleeve15so as not to be rotated about the longitudinal axis A with respect to the connection sleeve15while being allowed to slide along the outer circumferential surface of the connection sleeve15in the direction along the longitudinal axis A.

The locking protrusions12cprotrude radially inward from the inner circumferential surface of the stopper12aand extend in the direction along the longitudinal axis A.

The engagement ring12bis a toroidal member that is fixed to the proximal end of the rotation operation part11and that is provided coaxially with the rotating shaft8and the rotation operation part11, and grooves12ethat extend from a proximal-end surface of the engagement ring12bin the direction along the longitudinal axis A and into which the protrusions12care fitted in the direction along the longitudinal axis A are formed in the engagement ring12b. The many grooves12eare provided at intervals in the circumferential direction of the engagement ring12b.

As shown inFIG. 5A, at the lock position, the protrusions12cof the stopper12aare fitted into any of the grooves12e, thereby locking the rotation of the rotation operation part11with respect to the bending operation part10and the operation handle9. On the other hand, as shown inFIG. 5B, at the release position, which is closer to the proximal end than the lock position is, the protrusions12care disposed further toward the proximal end than the grooves12e, thereby allowing the rotation of the rotation operation part11with respect to the bending operation part10and the operation handle9.

Next, a surgical method using the treatment tool1will be described.

In order to treat the living tissue in the body of the patient Y by using the treatment tool1of this embodiment, as shown inFIG. 6, the shaft2is inserted into the treatment-tool holder60, thereby holding the treatment tool1at a fixed position with respect to the bed40. Then, the shaft2is inserted into the body via the channel of the endoscope20or the external channel attached to the endoscope20, and the shaft2is disposed at a position where the bending section7can be observed in an endoscopic image.

In the treatment-tool holder60, the shaft2can be moved in the direction along the longitudinal axis A and can be rotated about the longitudinal axis A. The operator X can advance, retract, and rotate the end effector in the body by moving and rotating the entire treatment tool1. Furthermore, the operator X can bend the bending section7in an arbitrary direction intersecting the longitudinal axis A through a tilt operation of the operation handle9, and can rotate the shaft2about the longitudinal axis A through rotation of the rotation operation part11, while maintaining the positions of the bending operation part10and the operation handle9with respect to the treatment-tool holder60.

Here, when the flexible section5is twisted about the longitudinal axis A in the body, this may cause a deviation between a tilt direction of the operation handle9(i.e., the direction of rotation of the ball14) and a bending direction of the bending section7in an endoscopic image. Prior to treatment of the living tissue using the end effector, the operator X adjusts the orientation of the bending section7about the longitudinal axis A such that the bending section7in the endoscopic image is bent in the direction corresponding to the tilt direction of the operation handle9.

Specifically, the operator X operates the operation handle9while viewing the endoscopic image on the display unit80and checks whether the bending section7is bent in the direction corresponding to the tilt direction of the operation handle9.

If the bending section7is bent in the direction corresponding to the tilt direction of the operation handle9, the operator X locks the rotation of the rotation operation part11by disposing the stopper12aof the rotation lock part12at the lock position, and then performs treatment using the end effector.

On the other hand, if the bending direction of the bending section7deviates with respect to the tilt direction of the operation handle9, the operator X disposes the stopper12aof the rotation lock part12at the release position and rotates the rotation operation part11to rotate the shaft2about the longitudinal axis A, thereby adjusting the orientation of the bending section7about the longitudinal axis A such that the bending section7is bent in the direction corresponding to the tilt direction of the operation handle9. Next, the operator X locks the rotation of the rotation operation part11by sliding the stopper12aup to the lock position, and then performs treatment using the end effector.

When the orientation of the end effector or the bending section7about the longitudinal axis A is changed after the rotation operation part11is locked by means of the rotation lock part12, the operator X rotates the entire treatment tool1about the longitudinal axis A while maintaining the state in which the rotation of the rotation operation part11is locked by means of the stopper12a. Accordingly, it is possible to change the orientations of the end effector and the bending section7while maintaining the adjusted correspondence relationship between the tilt direction of the operation handle9and the bending direction of the bending section7.

In this way, according to this embodiment, the shaft2and the bending operation part10can be relatively rotated about the longitudinal axis A, and, through rotation of the rotation operation part11, which is provided between the shaft2and the bending operation part10, the shaft2can be rotated about the longitudinal axis A while the orientation of the bending operation part10is maintained. Therefore, there is an advantage in that, when a deviation occurs between the tilt direction of the operation handle9and the bending direction of the bending section7, the shaft2is rotated through operation of the rotation operation part11, thereby making it possible to correct the deviation of the bending direction of the bending section7with respect to the tilt direction of the operation handle9. Furthermore, after the bending direction of the bending section7is adjusted with respect to the tilt direction of the operation handle9, the rotation of the rotation operation part11is locked by means of the rotation lock part12, thereby making it possible to operate the entire treatment tool1while maintaining the correspondence relationship between the tilt direction of the operation handle9and the bending direction of the bending section7.

In correcting the deviation between the tilt direction of the operation handle9and the bending direction of the bending section7, it is also possible to rotate, instead of the rotation operation part11, the bending operation part10and the operation handle9with respect to the rotation operation part11and the shafts2and8.

In a case in which the rotation transmission efficiency of the flexible section5is low, it is difficult to rotate the bending section7through rotation of the rotation operation part11. In this case, the bending operation part10and the operation handle9are rotated while the position of the rotation operation part11is held, thereby making it possible to efficiently correct the deviation between the tilt direction of the operation handle9and the bending direction of the bending section7.

In this embodiment, it is also possible to further provide a limiter that limits a rotation amount of the rotation operation part11with respect to the bending operation part10and the operation handle9.

FIG. 7shows an example limiter16. As shown inFIG. 7, the limiter16includes: a male screw16athat is formed at the proximal-end section of the rotating shaft8and that is coaxial with the shafts2and8; a round-shaped movable plate (movable body)16cthat has a female screw16bto be fastened to the male screw16aand that is linearly moved along the longitudinal axis A through rotation of the shaft8; and a pair of stopper surfaces (stoppers)16dthat regulate the range of movement of the movable plate16c.

The pair of stopper surfaces16dare provided, with a space therebetween in the direction along the longitudinal axis A, at both sides with respect to the movable plate16c. The movable plate16cabuts against any one of the stopper surfaces16d, thereby limiting further movement of the movable plate16cand also limiting further rotation of the rotation operation part11.

For example, in a case in which the rotation transmission efficiency of the flexible section5is 50%, when the rotation operation part11is rotated by 180°, the bending section7is rotated by only 90°. In order to be able to adjust the bending section7to an arbitrary orientation, the bending section7needs to be able to be rotated by 360° or more, regardless of the low rotation transmission efficiency of the flexible section5. According to the screw-type limiter16, which is shown inFIG. 7, the rotation angle range of the rotation operation part11is determined by the pitches of the screws16aand16band the distance between the pair of stopper surfaces16din the direction along the longitudinal axis A. Therefore, it is possible to easily design the maximum rotation amount of the rotation operation part11so as to realize the maximum rotation amount of the rotation operation part11required in accordance with the rotation transmission efficiency of the flexible section5. For example, according to the limiter16, the rotation amount of the rotation operation part11can be limited to the range from −360° to +360° inclusive.

An indicator for indicating, to the operator X, the position of the movable plate16cmay also be provided in the operation unit3. As shown inFIG. 8, for example, the indicator may be a window17that is provided in the stopper12aand that allows the movable plate16c, which is provided inside the stopper12a, to be seen from outside the stopper12a. By visibly checking the position of the movable plate16cbetween the stopper surfaces16d, through the window17, the operator X can grasp the current rotation amount of the rotation operation part11. Furthermore, because the operator X can determine, from the position of the movable plate16c, whether the rotation amount of the rotation operation part11has reached the maximum rotation amount, it is possible to prevent an excessive force from being applied to the rotation operation part11when the rotation operation part11is further rotated regardless of the fact that the rotation amount of the rotation operation part11has reached the maximum rotation amount.

In this embodiment, it is also possible to further provide a lock holding mechanism that restricts free sliding of the stopper12aof the rotation lock part12.

The lock holding mechanism is configured such that, while the stopper12ais allowed to slide when manually operated by the operator X, the position of the stopper12ais held in a state in which the operator X is not operating the stopper12a. By providing this lock holding mechanism, locking of the rotation operation part11performed by means of the rotation lock part12can be prevented from being unintentionally released.

As shown inFIG. 9, for example, the lock holding mechanism may be mounted on the outer circumferential surface of the connection sleeve15and may be formed of a resin material that produces friction with respect to the inner circumferential surface of the stopper12a.FIG. 9shows an example combination of an O-ring18aand a resin member18bthat is filled in a space between the O-ring18aand the inner circumferential surface of the stopper12a. Alternatively, the lock holding mechanism may include a spring that biases the stopper12atoward the lock position or may include a structure that is closely fitted together with a section of the stopper12aat each of the lock position and the release position, thus holding the position of the stopper12aby friction.

In this embodiment, although the ball14is rotated through the tilt operation of the operation handle9, instead of this, it is also possible to rotate the ball14through another operation.

For example, as shown inFIG. 10, it is also possible to adopt a trackball-type bending operation part10in which the ball14is directly operated by using a thumb of the operator X.

The invention of a surgical method according to the following features is derived from the above-described embodiment.

Additional Item 1

A surgical method using a treatment tool that includes: an elongated shaft that has a bending mechanism at a distal end thereof; an operation part that is connected to a proximal end of the shaft and that has an operation member capable of pivoting with respect to the shaft; a wire that passes through the inside of the shaft to connect the bending mechanism and the operation member and that is advanced and retracted in a direction along a longitudinal axis of the shaft through pivoting of the operation member, thus bending the bending mechanism; and a rotation mechanism that holds the operation part and the shaft so as to allow relative rotation thereof about the longitudinal axis of the shaft, the surgical method including:

an insertion step of inserting the shaft into a body;

an orientation adjustment step of adjusting, after the insertion step, a relative orientation of the operation member and the bending mechanism about the longitudinal axis by relatively rotating the operation part and the shaft about the longitudinal axis, such that a pivot direction of the operation member and a bending direction of the bending mechanism correspond to each other; and

a treatment step of treating living tissue after the adjustment step.

Additional Item 2

A surgical method according to Additional Item 1, further including a rotation lock step of locking, after the adjustment step, relative rotation of the operation part and the shaft about the longitudinal axis.

Additional Item 3

A surgical method according to Additional Item 2, further including a secondary adjustment step of adjusting, after the rotation lock step, the orientations of the bending mechanism and an end effector that is provided at the distal end of the shaft, about the longitudinal axis, in the body, by rotating the entire treatment tool about the longitudinal axis.

The above-described embodiment also leads to the following aspects.

In one aspect, a treatment tool includes: an elongated shaft that has a bending mechanism at a distal end thereof; an operation part that is connected to a proximal end of the shaft and that has an operation member capable of pivoting with respect to the shaft; a wire that passes through the inside of the shaft to connect the bending mechanism and the operation member and that is advanced and retracted in the direction along the longitudinal axis of the shaft through pivoting of the operation member, thus bending the bending mechanism; and a rotation mechanism that holds the operation part and the shaft so as to allow relative rotation thereof about the longitudinal axis of the shaft.

According to this aspect, when the operation member of the operation part is made to pivot, the wire, which extends in the pivot direction of the operation member, is pulled and retracted or is pushed and advanced, thus bending the bending mechanism. Therefore, the bending mechanism can be bent in the direction corresponding to the pivot direction of the operation member.

In this case, because the operation part and the shaft can be relatively rotated about the longitudinal axis by means of the rotation mechanism, it is possible to change the relative orientation of the operation part and the bending mechanism about the longitudinal axis through the relative rotation of the operation part and the shaft. Therefore, a deviation between the pivot direction of the operation member and the bending direction of the bending mechanism can be corrected through the relative rotation of the operation part and the shaft about the longitudinal axis.

In the above-described aspect, in the bending mechanism, the wire may be fixed at a position away from the longitudinal axis in a direction intersecting the longitudinal axis, the bending mechanism may be able to be bent such that the retracted wire is located radially inward, and the shaft may be able to be subjected to twist deformation about the longitudinal axis.

According to this shaft, a deviation between the pivot direction of the operation member and the bending direction of the bending mechanism tends to occur due to twisting of the shaft about the longitudinal axis. Therefore, the rotation mechanism is particularly suitable for a treatment tool that includes such a shaft.

The above-described aspect may further include a lock mechanism that locks relative rotation of the shaft and the operation part relative to each other about the longitudinal axis.

After the correspondence relationship between the pivot direction of the operation member and the bending direction of the bending mechanism is adjusted, the relative rotation of the shaft and the operation part is locked by means of the lock mechanism, thereby making it possible to easily rotate the entire treatment tool while maintaining the correspondence relationship between the pivot direction of the operation member and the bending direction of the bending mechanism.

In the above-described aspect, the shaft may include an inner sheath into which the wire is inserted; a proximal-end section of the inner sheath may be fixed with respect to the operation part at a position between the shaft and the operation member; and the wire may be drawn from the proximal-end section of the inner sheath and may be connected to the operation member.

When the shaft and the operation part are relatively rotated, because the proximal-end section of the inner sheath is fixed with respect to the operation part, the wire is not twisted about the longitudinal axis, between the proximal-end section of the inner sheath and the operation member. Accordingly, a change in the path length of the wire caused by the relative rotation of the shaft and the operation part can be suppressed. Furthermore, in a case in which a plurality of wires are provided, it is possible to prevent entanglement of the wires between the shaft and the operation member.

The above-described aspect may further include a limiter that limits the amount of relative rotation of the operation part and the shaft about the longitudinal axis.

By doing so, it is possible to prevent excessive twisting of the wire caused by excessive relative rotation of the operation part and the shaft.

In the above-described aspect, the limiter may include: a male screw that is provided so as to be coaxial with the shaft and that is rotated integrally with the shaft; a movable body that has a female screw to be fastened to the male screw and that is linearly moved along the longitudinal axis through rotation of the shaft; and a pair of stoppers that are disposed, with a space therebetween in the direction along the longitudinal axis, at both sides with respect to the movable body.

When the male screw is rotated with respect to the operation part through rotation of the shaft, the movable body, which is fastened to the male screw in the female screw thereof, is linearly moved along the longitudinal axis. The rotation of the shaft is limited at a position where the movable body abuts against one of the stoppers. Specifically, the maximum rotation amount of the shaft is determined by the pitches of the male screw and the female screw and the distance between the pair of stoppers in the direction along the longitudinal axis. Therefore, a desired maximum relative-rotation amount of the shaft and the operation part can be easily realized.

REFERENCE SIGNS LIST