WO2020161857A1

WO2020161857A1 - Guide sheath for use in surgery

Info

Publication number: WO2020161857A1
Application number: PCT/JP2019/004413
Authority: WO
Inventors: 雅浩藤井; 紀明山中
Original assignee: オリンパス株式会社
Priority date: 2019-02-07
Filing date: 2019-02-07
Publication date: 2020-08-13

Abstract

The purpose of the present invention is to provide a guide sheath for use in surgery which can stably maintain the shape of a bent treatment instrument regardless of the bending angle. This guide sheath for use in surgery is provided with: a hard tubular outer sheath (2); a bending part (4) having a plurality of joint members (4a) which are arranged in the longitudinal direction of the outer sheath (2) and are able to swing around an axis intersecting the longitudinal direction to hit other adjacent joint members (4a); an inner sheath (3) which is arranged in the longitudinal direction within the outer sheath (2), has an outer diameter substantially equal to the inner diameter of the outer sheath (2), and has the bending part (4) at a distal end part thereof; and a force transmission member (5) for transmitting bending force for bending the bending part (4). The inner sheath (3) is capable of relative movement within the outer sheath (2) in the longitudinal direction. By moving the inner sheath (3), the amount of protrusion of the bending part (4) from the distal end of the outer sheath (2) can be varied.

Description

Surgical guide sheath

The present invention relates to a surgical guide sheath, and more particularly to a surgical guide sheath for a soft treatment tool.

Conventionally, a support component for using a flexible endoscope as a laparoscope is known (for example, refer to Patent Document 1). The flexible endoscope has a flexible tube and a bending portion connected to the distal end of the flexible tube. Since the flexible tube loosens due to gravity in the abdominal cavity, it is difficult to manipulate the tip of the flexible endoscope as intended. The support component of Patent Document 1 has a trocar that guides the flexible endoscope inside the abdominal cavity, and the trocar maintains the linear shape of the flexible tube.

Patent No. 5989411

As a minimally invasive surgery for the mediastinum, thoracoscopic surgery has been proposed in which a thoracoscope and a treatment tool are inserted from below the xiphoid to the mediastinum. An obstacle such as the heart exists in the path of the treatment instrument from below the xiphoid process to the mediastinum. Therefore, it is necessary to operate the tissue in the mediastinum with the treatment tool while the treatment tool is curved so as to avoid the obstacle.

The bending portion of a general flexible endoscope and a soft treatment tool is configured to bend by the tension of the wire, and the bending angle of the bending portion increases in proportion to the tension of the wire. The shape of such a curved portion is maintained only by the tension of the wire, and the rigidity of the curved portion is low. During the operation of the tissue in the mediastinum by the end effector at the tip of the treatment tool, a reaction force from the tissue in the mediastinum is applied to the end effector. In a state in which the bending portion is bent to avoid an obstacle, the shape and shape of the bending portion is easily changed by the reaction force applied to the end effector, so that the position and the posture of the end effector are not stable, and the operation is difficult.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a surgical guide sheath that can stably maintain the curved shape of a treatment tool regardless of the bending angle.

One embodiment of the present invention includes a rigid and rigid tubular outer sheath and a plurality of joint members arranged in a longitudinal direction of the outer sheath, and the plurality of joint members are provided around an axis line intersecting the longitudinal direction. A curved portion that can swing until it abuts another joint member that is adjacent to the joint member, and a curved portion that is arranged in the outer sheath along the longitudinal direction and that has an outer diameter that is substantially equal to the inner diameter of the outer sheath, A tubular inner sheath having the bending portion, and a force transmitting member transmitting a bending force for bending the bending portion, wherein the inner sheath is relatively movable in the longitudinal direction in the outer sheath, A surgical guide sheath in which the amount of protrusion of the curved portion from the distal end of the outer sheath is variable by movement of the inner sheath.

According to the present invention, the curved shape of the treatment tool can be stably maintained regardless of the bending angle.

1 is an overall configuration diagram of a surgical guide sheath according to an embodiment of the present invention. It is a side view of an example of 1 composition of a curve part of an inner sheath. It is a side view of another configuration example of the curved portion of the inner sheath. It is a longitudinal cross-sectional view showing an internal configuration diagram of a bending portion. It is a figure explaining the bending operation of a bending part. It is a figure explaining the bending operation of a bending part. It is a figure explaining the bending operation of a bending part. It is a figure explaining the usage method of the surgical guide sheath of FIG. It is a side view of the modification of an outer sheath. It is a longitudinal cross-sectional view of a modification of the surgical guide sheath of FIG. FIG. 7B is a vertical cross-sectional view showing a state where the inner sheath of the surgical guide sheath of FIG. 7A is projected from the outer sheath. It is a side view of another modification of the surgical guide sheath of FIG. FIG. 8B is a partial vertical cross-sectional view of the surgical guide sheath of FIG. 8A showing the configuration of the lock mechanism. It is a longitudinal cross-sectional view of another modification of the surgical guide sheath of FIG. FIG. 9B is a vertical cross-sectional view showing a state where the curved portion of the inner sheath of the surgical guide sheath of FIG. 9A is projected from the outer sheath. It is a longitudinal cross-sectional view of another modification of the surgical guide sheath of FIG. FIG. 10B is a vertical cross-sectional view showing a state where the curved portion of the inner sheath of the surgical guide sheath of FIG. 10A is projected from the outer sheath. It is a longitudinal cross-sectional view of another modification of the surgical guide sheath of FIG. It is a longitudinal cross-sectional view of another modification of the surgical guide sheath of FIG. FIG. 12B is a vertical cross-sectional view showing a state where the curved portion of the inner sheath of the surgical guide sheath of FIG. 12A is projected from the outer sheath. It is a partial longitudinal cross-sectional view of another modification of the surgical guide sheath of FIG. It is a longitudinal cross-sectional view of another modification of the surgical guide sheath of FIG. FIG. 14B is a longitudinal sectional view showing a state where the curved portion of the inner sheath of the surgical guide sheath of FIG. 14A is projected from the outer sheath. It is a side view of the modification of the curved part of an inner sheath. It is a cross-sectional view of a modified example of the outer sheath and the inner sheath.

A surgical guide sheath 1 according to an embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the surgical guide sheath 1 according to the present embodiment has a rigid tubular outer sheath 2 and a curved portion 4 at the distal end, and is arranged in the outer sheath 2 along the longitudinal direction. A tubular inner sheath 3, a force transmitting member 5 (see FIG. 3) that transmits a bending force that bends the bending portion 4 to the bending portion 4, and an operating portion 6 for a user to operate the inner sheath 3. Equipped with. The surgical guide sheath 1 is for guiding the soft treatment tool 20 in the body, and the treatment tool 20 is inserted into the inner sheath 3.

The treatment instrument 20 includes a flexible elongated insertion portion 21, an end effector 22 arranged on the distal end side of the insertion portion 21, a bending portion 23 connecting the insertion portion 21 and the end effector 22, and an insertion portion. The drive unit 24 is connected to the base end of the unit 21. The end effector 22 is a part that treats a living tissue, and is, for example, forceps or a scalpel. The bending portion 23 has, for example, a plurality of joints arranged in the longitudinal direction, and can be bent in a plurality of directions. The drive unit 24 has, for example, a motor, and bends the bending portion 23 by pulling a wire connected to the bending portion 23 with the motor.

The outer sheath 2 has a linear shape and has a rigidity that can maintain the linear shape regardless of the bending force transmitted from the force transmitting member 5 to the bending portion 4. Therefore, the bending portion 4 cannot be bent inside the outer sheath 2, and can be bent outside the outer sheath 2 according to the bending force from the force transmission member 5 (see FIGS. 4A to 4C).

The outer diameter of the inner sheath 3 is almost equal to the inner diameter of the outer sheath 2, and the inner sheath 3 is movable in the longitudinal direction with respect to the outer sheath 2. The substantially equal range is a range in which the outer diameter of the inner sheath 3 is smaller than the inner diameter of the outer sheath 2 by one turn (20% or less). By the movement of the inner sheath 3 in the longitudinal direction, the amount of protrusion of the bending portion 4 from the tip of the outer sheath 2 continuously changes. The treatment tool 20 is inserted into the inner sheath 3 and rotatable in the inner sheath 3 about the longitudinal axis.

2A and 2B show a configuration example of the bending portion 4. The bending portion 4 has a plurality of joint members 4 a arranged in the longitudinal direction of the inner sheath 3. Each joint member 4a is swingable around a swing axis A that intersects the longitudinal direction of the inner sheath 3, and the swing axes A of the plurality of joint members 4a are parallel to each other. When the plurality of joint members 4a swing in the same direction, the bending portion 4 bends in an arc shape as shown by a chain double-dashed line in the figure. The joint member 4a shown in FIG. 2A is an annular bending piece that is swingably connected to each other. As shown in FIG. 2B, a V-shaped groove may be formed on the outer peripheral surface of the inner sheath 3 having flexibility, and the joint member 4a may be composed of a portion sandwiched by two adjacent grooves.

Between two joint members 4a adjacent to each other, a gap d for allowing the swing of each joint member 4a is provided on both sides in the radial direction sandwiching the swing axis A in a direction orthogonal to the swing axis A. It is provided. As the swing angle of each joint member 4a increases, the inner clearance d of the curved shape narrows. Each joint member 4a can be swung up to the maximum swing angle at which the joint member 4a abuts another joint member 4a adjacent to the proximal end on the inner side of the curved shape.

The force transmission member 5, as shown in FIG. 3, is a long wire arranged in the inner sheath 3 along the longitudinal direction. In the bending portion 4, the wire 5 is arranged radially outside the inner sheath 3 with respect to the swing axis A. The wiring path of the wire 5 in the inner sheath 3 is defined by, for example, a passage 5a extending from the distal end to the proximal end of the inner sheath 3. The tip of the wire 5 is fixed to the tip of the bending portion 4, and the base end of the wire 5 is connected to the operating portion 6.

The operation portion 6 is a portion gripped by the user and is connected to the proximal end portion of the inner sheath 3. The user can change the amount of protrusion of the bending portion 4 from the distal end of the outer sheath 2 by holding the operating portion 6 with one hand and pushing and pulling the inner sheath 3 in the longitudinal direction. Further, the user can rotate the inner sheath 3 around the longitudinal axis in the outer sheath 2 by rotating the operation unit 6 around the longitudinal axis of the inner sheath 3.

The operation unit 6 is provided with a handle 6a to which the proximal end of the wire 5 is connected. When the user operates the handle 6 a, the wire 5 is pulled, and as shown in FIGS. 4A to 4C, the tension (curving force) of the wire 5 causes the bending portion to move in a direction in which the wire 5 is arranged inside the curved shape. 4 bends. At this time, of the bending portion 4, only the protruding portion 4 b that protrudes from the tip of the outer sheath 2 and is arranged outside the outer sheath 2 bends due to the tension of the wire 5.

The greater the tension of the wire 5, the greater the swing angle of each joint member 4a of the protruding portion 4b. The pulling amount of the wire 5 by the operation of the handle 6a is set so that the tension for swinging each joint member 4a of the protruding portion 4b to the maximum swing angle is applied to the wire 5. As described above, since the swing angle of each joint member 4a of the protruding portion 4b is controlled to the maximum swing angle by the tension of the wire 5, the bending angle of the protruding portion 4b increases as the protruding portion 4b becomes longer. Therefore, the user can adjust the bending angle of the protruding portion 4b by changing the amount of protrusion of the bending portion 4 from the tip of the outer sheath 2 by pushing and pulling the inner sheath 3.

Next, the operation of the surgical guide sheath 1 configured as described above will be described by taking a thoracoscopic operation of the mediastinum as an example.
In order to treat the mediastinum using the surgical guide sheath 1 according to the present embodiment, the thoracoscope and the

sheaths

2 and 3 of the surgical guide sheath 1 are inserted from below the xiphoid process B of the patient P to the mediastinum. .. An obstacle C such as a heart exists on the path of the

sheaths

2 and 3 between below the xiphoid process B and the mediastinum. In order to avoid the obstacle C, the bending portion 4 of the inner sheath 3 is bent.

Specifically, as shown in FIG. 5, the inner sheath 3 is moved toward the distal end side with respect to the outer sheath 2, and at least a part of the curved portion 4 is projected from the distal end of the outer sheath 2. Next, the wire 5 is pulled by operating the handle 6a. As a result, the protruding portion 4b of the bending portion 4 protruding from the tip of the outer sheath 2 is bent. Since the joint members 4a of the projecting portions 4b swing by the tension of the wire 5 to the maximum swinging angles at which they hit each other, the curved projecting portions 4b are structurally stable. Further, each joint member 4a is stably maintained at the maximum swing angle by the tension of the wire 5. Therefore, high rigidity of the curved protruding portion 4b is realized, and the curved shape of the protruding portion 4b is stably maintained. The user adjusts the bending angle of the protruding portion 4b so that the protruding portion 4b avoids the obstacle C by moving the inner sheath 3 in the longitudinal direction with respect to the outer sheath 2 and changing the length of the protruding portion 4b. ..

Next, the treatment tool 20 is inserted from below the xiphoid process B to the mediastinum via the inner sheath 3, and the end effector 22 is placed near the tissue in the mediastinum to be treated. The insertion portion 21 is curved so as to avoid the obstacle C according to the curved shape of the protruding portion 4b. The position and posture of the end effector 22 with respect to the tissue in the mediastinum is roughly determined by the curved shape of the protruding portion 4b. Next, while finely adjusting the position and posture of the end effector 22 with respect to the tissue in the mediastinum by the bending of the bending portion 23, the tissue in the mediastinum is treated by the end effector 22.

During the treatment of the tissue in the mediastinum by the end effector 22, the reaction force from the tissue in the mediastinum acts on the end effector 22. For example, when the tissue in the mediastinum is grasped and lifted upward by the end effector 22 such as forceps, a downward reaction force acts on the end effector 22. According to the present embodiment, the curved shape of the insertion portion 21 is stably maintained by the protruding portion 4b having high rigidity regardless of the reaction force acting on the end effector 22, and thus during treatment of the tissue in the mediastinum. There is an advantage that the position and posture of the end effector 22 can be stabilized. Further, since the high rigidity of the protruding portion 4b is realized at any bending angle, there is an advantage that the bending shape of the insertion portion 21 can be stably maintained regardless of the bending angle.

In the present embodiment, the outer sheath 2 is linear, but instead of this, it may be curved as shown in FIG. In this case, the portion other than the curved portion 4 of the inner sheath 3 is flexible so that the inner sheath 3 can move inside the outer sheath 2 while being deformed along the curved shape of the outer sheath 2.

In this embodiment, as shown in FIGS. 7A and 7B, the proximal end of the wire 5 may be fixed to the fixing portion 7 fixed to the outer sheath 2. Reference numeral 8 is a pulley.
It is preferable that tension is applied to the wire 5 in a state where the distal end of the inner sheath 3 is aligned with the distal end of the outer sheath 2 shown in FIG. 7A. As shown in FIG. 7B, as the amount of protrusion of the curved portion 4 from the distal end of the outer sheath 2 increases, the wire 5 extends and the tension of the wire 5 increases. That is, simply by projecting the bending portion 4 from the tip of the outer sheath 2, the joint member 4a of the projecting portion 4b can be swung to the maximum swing angle to bend the projecting portion 4b. Therefore, when the fixing portion 7 is provided, the user does not need to operate the handle 6a.

In the present embodiment, as shown in FIGS. 8A and 8B, a lock mechanism 9 for fixing and releasing the longitudinal position of the inner sheath 3 with respect to the outer sheath 2 may be further provided.
The lock mechanism 9 has, for example, a plurality of grooves 9a provided on the outer peripheral surface of the outer sheath 2 and a protrusion 9b provided on the inner sheath 3 and fitted in the groove 9a. The plurality of grooves 9a are arranged in the longitudinal direction of the outer sheath 2. The protrusion 9b is supported by a knob 9d fixed to the inner sheath 3 and arranged outside the outer sheath 2 via a spring 9c, and is biased radially inward of the inner sheath 3 by the spring 9c. The user can change the groove 9a into which the protrusion 9b fits by operating the knob 9d.

By fitting the protrusion 9b into the groove 9a, the position of the inner sheath 3 with respect to the outer sheath 2 in the longitudinal direction is fixed. The protrusion 9b moves outward in the radial direction against the biasing force of the spring 9c, whereby the fixation of the inner sheath 3 to the outer sheath 2 is released.
According to this configuration, after the protruding portion 4b of the bending portion 4 is curved, the outer sheath 2 and the inner sheath 3 are fixed to each other by the lock mechanism 9, so that the protruding portion 4b due to the unintended relative movement of the

sheaths

2 and 3 is caused. It is possible to prevent the change of the length and the bending angle.

9A and 9B show a combination of the fixed portion 7 and the lock mechanism 9. When the base end of the wire 5 is fixed to the fixing portion 7, the inner sheath 3 is pulled toward the base end side by the tension of the wire 5 in a state where the bending portion 4 is projected from the distal end of the outer sheath 2. Therefore, in order to stably maintain the length and the bending angle of the protruding portion 4b, it is preferable to fix the outer sheath 2 and the inner sheath 3 to each other by the lock mechanism 9.

The configuration including the fixing portion 7 may further include an elastic body 10 arranged at the proximal end of the wire 5 and fixed to the outer sheath 2 by the fixing portion 7 as shown in FIGS. 10A and 10B.
The elastic body 10 is, for example, a coil spring. The elastic body 10 connects the wire 5 and the fixed portion 7, and is elastically expandable in the longitudinal direction of the wire 5.

According to this configuration, the elastic body 10 extends when the bending portion 4 projects from the tip of the outer sheath 2, and the extension amount of the elastic body 10 increases as the protruding amount of the bending portion 4 increases. Therefore, compared with the example of FIGS. 7A and 7B in which the elastic body 10 is not provided, the change in the tension of the wire 5 when the bending portion 4 is projected from the distal end of the outer sheath 2 can be moderated. .. When a constant force spring is used as the elastic body 10, the tension of the wire 5 can be made constant regardless of the amount of protrusion of the bending portion 4 from the tip of the outer sheath 2.

The fixing portion 7 and the elastic body 10 can also be provided in the

sheaths

2 and 3 that are not provided with the pulley 8 and the lock mechanism 9, as shown in FIG.

In this embodiment, as shown in FIGS. 12A and 12B, the movable member 11 is connected to the proximal end of the wire 5 and supported by the outer sheath 2, and the movable member 11 is interlocked with the movement of the inner sheath 3. The moving mechanism 12 may be further provided.
The movable member 11 is movable with respect to the outer sheath 2 in the longitudinal direction of the outer sheath 2. The interlocking mechanism 12 interlocks with the movement of the inner sheath 3 to move the movable member 11 in a direction for keeping the tension of the wire 5 constant. According to this configuration, when the bending portion 4 projects from the distal end of the outer sheath 2, the distal end of the wire 5 and the proximal end of the wire 5 are moved by the interlocking mechanism 12 at the same time, whereby the length and tension of the wire 5 are increased. Can be reduced.

For example, the interlocking mechanism 12 includes a rack 12a provided on the outer peripheral surface of the inner sheath 3, a rack 12b provided on the movable member 11, and a double gear 12c meshing with the

racks

12a and 12b. The teeth of the rack 12a are arranged in the longitudinal direction of the inner sheath 3, and the teeth of the rack 12b are arranged in the longitudinal direction of the outer sheath 2. The double gear 12c has two coaxial gears, one gear meshes with the rack 12a, and the other gear meshes with the rack 12b. Such an interlocking mechanism 12 moves the movable member 11 in a direction opposite to the moving direction of the inner sheath 3.

In order to keep the length and tension of the wire 5 constant regardless of the protruding amount of the bending portion 4 from the tip of the outer sheath 2, it is preferable that the moving amount of the movable member 11 by the interlocking mechanism 12 satisfies the following formula.
Xs:Xm=1:1-rs/rc
However, Xs is the amount of movement of the inner sheath 3 in the longitudinal direction, Xm is the amount of movement of the movable members 11 in the longitudinal direction of the

sheaths

2, 3, rs is the radius (outer radius) of the inner sheath 3, and rc is It is the radius of curvature of the protruding portion 4b of the curved portion 4 (the radius of curvature of the center line of the protruding portion 4b). The radius of curvature rc is substantially constant regardless of the length of the protruding portion 4b.

Although the tension of the force transmitting member 5 is used as the bending force for bending the bending portion 4 in the present embodiment, the elastic restoring force of the force transmitting member 51 may be used instead of this.
That is, as shown in FIG. 13, even if the tip portion 51a of the force transmission member 51 arranged in the bending portion 4 has a curved shape in a free state in which an external force does not act, and is elastically deformable into a linear shape. Good. For example, the force transmission member 51 is a leaf spring or a shape memory alloy having a curved tip portion 51a. When the curved portion 4 projects from the tip of the outer sheath 2, the protruding portion 4b bends due to the elastic restoring force of the tip portion 51a from the linear shape to the curved shape. A plurality of force transmission members 51 may be arranged in the inner sheath 3 in order to increase the rigidity of the curved protruding portion 4b.

Alternatively, in the present embodiment, the pressing force of the force transmission member 52 may be used as the bending force for bending the bending portion 4. For example, as shown in FIGS. 14A and 14B, an elastic rod 52 may be provided as a force transmission member. The tip of the elastic rod 52 is fixed to the tip of the inner sheath 3. When a pressing force acts on the distal end of the inner sheath 3 from the elastic rod 52, the protruding portion 4b of the bending portion 4 bends in a direction in which the elastic rod 52 is arranged outside the curved shape, as shown in FIG. 14B.

A biasing member 13 that biases the elastic rod 52 toward the tip side may be further provided. The biasing member 13 is, for example, a compression spring in a compressed state arranged between the base end of the inner sheath 3 and the base end of the elastic rod 52. The urging force of the urging member 13 is used as a power source for pressing the elastic rod 52 toward the tip side. Therefore, the bending portion 4 can be bent by the urging force of the urging member 13 only by protruding the bending portion 4 from the tip of the outer sheath 2.

In the present embodiment, as shown in FIG. 15, the wire 5 may be wired in the inner sheath 3 so that the bending portion 4 bends in an S shape. Specifically, the wire 5 passes on the opposite side in the radial direction at the distal end side portion and the proximal end side portion of the bending portion 4. By such wiring of the wire 5, the distal end side portion and the proximal end side portion of the bending portion 4 can be bent in mutually opposite directions.

In the present embodiment, the cross-sectional shape of the inner peripheral surface of the outer sheath 2 and the cross-sectional shape of the outer peripheral surface of the inner sheath 3 may be non-circular shapes that fit with each other. For example, the cross-sectional shape of the inner peripheral surface of the outer sheath 2 and the cross-sectional shape of the outer peripheral surface of the inner sheath 3 may be elliptical as shown in FIG. 16, or a curve and a straight line such as an arc. It may be a combination with.
Such a non-circular cross-sectional shape prevents rotation of the inner sheath 3 about the longitudinal axis within the outer sheath 2. Therefore, the rotation of the inner sheath 3 can be controlled by the rotation of the outer sheath 2.

DESCRIPTION OF SYMBOLS 1 Operation guide sheath 2 Outer sheath 3 Inner sheath 4 Bending part

4a Joint member

4b Projection part 5 Force transmission member, wire 51 Force transmission member 52 Force transmission member, elastic rod 7 Fixed part 9 Lock mechanism 10 Elastic body 11 Movable member 12 Interlocking mechanism 20 Treatment tool A Swing axis (axis)

Claims

A rigid and tubular outer sheath,
A bending portion having a plurality of joint members arranged in the longitudinal direction of the outer sheath, and the plurality of joint members being capable of swinging about an axis intersecting the longitudinal direction until it abuts another adjacent joint member. When,
A tubular inner sheath that is arranged in the outer sheath along the longitudinal direction, has an outer diameter substantially equal to the inner diameter of the outer sheath, and has the curved portion at the distal end portion,
A force transmission member that transmits a bending force that bends the bending portion,
A surgical guide sheath in which the inner sheath is relatively movable in the longitudinal direction in the outer sheath, and the amount of protrusion of the curved portion from the distal end of the outer sheath is variable due to the movement of the inner sheath.
The force transmission member is an elongated member arranged along the longitudinal direction of the inner sheath, and the tip end portion of the force transmission member is fixed to the tip end portion of the bending portion,
The surgical guide sheath according to claim 1, wherein the bending force is a tension of the force transmission member.
An elastic body arranged at the base end of the force transmission member,
A fixing portion for fixing the elastic body to the outer sheath,
The surgical guide sheath according to claim 2, wherein the elastic body is elastically expandable in the longitudinal direction of the force transmission member.
A movable member connected to the proximal end of the force transmission member and movable in the longitudinal direction of the outer sheath;
The surgical guide sheath according to claim 2, further comprising: an interlocking mechanism that interlocks with the movement of the inner sheath to move the movable member in a direction to keep the tension of the force transmitting member constant.
The surgical guide sheath according to claim 4, wherein the moving amount of the movable member by the interlocking mechanism satisfies the following expression.
Xs:Xm=1:1-rs/rc
However,
Xs is the amount of movement of the inner sheath in the longitudinal direction,
Xm is the amount of movement of the movable member in the longitudinal direction,
rs is the radius of the inner sheath,
rc is the radius of curvature of the curved portion of the inner sheath,
Is.
The surgical guide sheath according to any one of claims 3 to 5, further comprising a lock mechanism that fixes and unlocks the longitudinal position of the inner sheath with respect to the outer sheath.
The surgical guide sheath according to claim 1, wherein a distal end portion of the force transmission member arranged in the curved portion has a curved shape in a free state and is elastically deformable into a linear shape.
The surgical guide sheath according to any one of claims 1 to 7, wherein a cross-sectional shape of the inner peripheral surface of the outer sheath and a cross-sectional shape of the outer peripheral surface of the inner sheath are non-circular shapes that fit with each other. ..