Advance and retreat assist tool for endoscopic treatment instrument

1. An advance and retreat assist tool for an endoscopic treatment instrument, the advance and retreat assist tool comprising:

a base unit comprising a first hole portion which has a first central axis and a second hole portion which has a second central axis slanted relative to the first central axis and which is in communication with the first hole portion;

an attachment portion which attaches the base unit to a treatment instrument insertion portion provided in a grasping portion of an endoscope so that a side of the first hole portion having the first central axis faces a treatment instrument insertion hole portion and so that the base unit is rotatable around a central axis of the treatment instrument insertion hole portion;

a first tubular member provided to have a third central axis which is provided along a direction of the second central axis and is provided coaxially with the second central axis, the endoscopic treatment instrument being inserted into and fixed to the first tubular member;

a rotary portion into which the first tubular member is inserted and which rotates around the third central axis of the first tubular member; and

an advance and retreat mechanism which converts a rotation force of the rotary portion to an advance and retreat force along a direction of the third central axis of the first tubular member to advance and retreat the first tubular member and endoscopic treatment instrument when the rotary portion rotates while preventing rotation of the first tubular member.

2. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 1 , wherein

a central axis direction of the treatment instrument insertion hole portion is slanted relative to a central axis direction of the grasping portion, and

the attachment portion rotates around the central axis of the treatment instrument insertion hole portion so that an angle θ1>an angle θ2 when the rotary portion is rotated and so that an angle θ3>the angle θ1 when the endoscopic treatment instrument does not need to be advanced and retreated and when the rotary portion is not operated,

an angle formed between the central axis direction of the treatment instrument insertion hole portion and the central axis direction of the grasping portion being the angle θ1,

an angle formed between the direction of the second central axis and the central axis direction of the grasping portion when the rotary portion is operated being the angle θ2,

an angle formed between the direction of the second central axis and the central axis direction of the grasping portion when the endoscopic treatment instrument does not need to be advanced and retreated and when the rotary portion is not operated being the angle θ3.

3. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 2 , wherein the attachment portion comprises

a cylindrical body portion which is removably attached to the treatment instrument insertion portion so that the body portion is rotatable around the central axis of the treatment instrument insertion hole portion, and

a cylindrical support portion which supports the base unit so that the first central axis is provided coaxially with the central axis of the treatment instrument insertion hole portion and so that the first hole portion faces the treatment instrument insertion hole portion.

4. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 3 , wherein

the support portion is removably attached to the body portion, and

while the body portion is attached to the treatment instrument insertion portion, the support portion is screwed into the body portion, and the support portion is thereby attached to the body portion.

5. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 4 , wherein

when the support portion is attached to the body portion, an edge portion of the treatment instrument insertion hole portion is provided between the support portion and the body portion in the central axis direction of the treatment instrument insertion hole portion, and

the support portion is attached to the body portion so that the support portion presses the edge portion of the treatment instrument insertion hole portion into the body portion, and the attachment portion is fixed to the treatment instrument insertion portion.

6. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 5 , further comprising

an interference prevention member which intervenes between the support portion and the edge portion of the treatment instrument insertion hole portion in the central axis direction of the treatment instrument insertion hole portion and which prevents interference between the support portion and the edge portion of the treatment instrument insertion hole portion.

7. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 5 , wherein

the body portion has a cutout portion which is formed by a depression of a part of an edge portion of the body portion in a central axis direction of the body portion, and

the body portion is pressed into the treatment instrument insertion portion from a side surface of the treatment instrument insertion portion via the cutout portion in a diametrical direction of the body portion, and is thereby attached to the treatment instrument insertion portion.

8. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 7 , further comprising:

a distal end support portion which supports a distal end portion of the body portion;

an insertion support portion which supports the treatment instrument insertion portion; and

an urging portion which is connected to the distal end support portion and the insertion support portion and which urges at least one of the distal end portion of the attachment portion via the distal end support portion and the treatment instrument insertion portion via the insertion support portion toward the other.

9. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 2 , wherein the attachment portion comprises

a distal end portion which is attached to the treatment instrument insertion portion so that the distal end portion of the attachment portion is removably attached to the treatment instrument insertion portion and is also rotatable around the central axis of the treatment instrument insertion hole portion, and

a proximal end portion which is removably attached to the base unit and also supports the base unit.

10. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 9 , further comprising

an interference prevention member which intervenes between the distal end portion of the attachment portion and an edge portion of the treatment instrument insertion hole portion in the central axis direction of the treatment instrument insertion hole portion and which prevents interference between the distal end portion of the attachment portion and the edge portion of the treatment instrument insertion hole portion.

11. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 10 , wherein

the distal end portion of the attachment portion has a cutout portion which is formed by the depression of a part of an edge portion of the distal end portion of the attachment portion in the central axis direction of the attachment portion, and

the distal end portion of the attachment portion is pressed into the treatment instrument insertion portion from the side surface of the treatment instrument insertion portion via the cutout portion in the diametrical direction of the body portion, and is thereby attached to the treatment instrument insertion portion.

12. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 10 , further comprising:

a distal end support portion which supports the distal end portion of the attachment portion;

an insertion support portion which supports the treatment instrument insertion portion; and

an urging portion which is connected to the distal end support portion and the insertion support portion and which urges at least one of the distal end portion of the attachment portion via the distal end support portion and the treatment instrument insertion portion via the insertion support portion toward the other.

13. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 9 , wherein

the distal end portion of the attachment portion has claw portions which extend along the central axis direction of the attachment portion and then bend toward the central axis of the attachment portion, and

the distal end portion of the attachment portion is attached to the treatment instrument insertion portion when the claw portions are caught on the edge portion of the treatment instrument insertion hole portion.

14. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 1 , wherein

the advance and retreat mechanism intervenes between the rotary portion and the first tubular member, and the advance and retreat mechanism converts a rotation force of the rotary portion to an advance and retreat force of the first tubular member, transmits the advance and retreat force to the first tubular member, and thereby advances and retreats the first tubular member when the rotary portion rotates.

15. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 14 , wherein the advance and retreat mechanism comprises

a protrusion portion which is provided straight along a diametrical direction of the first tubular member and which is engaged with circumferential surface of the first tubular member,

a second tubular member having a portion which is fitted into and thus fixed to the second hole portion to be provided along the third central axis of the first tubular member, and a long opening portion provided in a circumferential surface of the second tubular member, the first tubular member being inserted into the second tubular member so that the protrusion portion is inserted through the long opening portion, and

a third tubular member having a central axis provided along a central axis of the second tubular member, and a spiral opening portion provided in a circumferential surface of the third tubular member, the second tubular member being inserted into the third tubular member so that part of the spiral opening portion is in communication with part of the long opening portion and so that the protrusion portion which is inserted through the long opening portion is inserted into the spiral opening portion, the third tubular member being inserted into the rotary portion to rotate together with the rotary portion.

16. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 15 , wherein

the third tubular member rotates in response to a rotation of the rotary portion, and the spiral opening portion thereby rotates,

the protrusion portion moves in the long opening portion along a central axis direction of the second tubular member as a result of a rotation of the spiral opening portion,

the protrusion portion abuts on an edge portion of the long opening portion, so that the first tubular member with which the protrusion portion is engaged is prevented from rotating around the third central axis of the first tubular member, and

the spiral opening portion rotates, and the protrusion portion moves in the long opening portion, so that the first tubular member advances and retreats while a rotation of the first tubular member around the third central axis of the first tubular member is prevented.

17. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 1 , further comprising

a regulating mechanism which regulates the first tubular member when the first tubular member advances and retreats.

18. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 1 , wherein

a proximal end portion of the first tubular member projects outside a proximal end portion of the rotary portion along the direction of the third central axis of the first tubular member.

19. The advance and retreat assist tool for the endoscopic treatment instrument according to claim 1 , further comprising

a support unit which supports the first tubular member so that the first tubular member is prevented from moving in a direction that intersects at right angles with the direction of the third central axis of the first tubular member.