Patent Publication Number: US-2022233197-A1

Title: Endoscope treatment device

Description:
RELATED APPLICATION DATA 
     This application is based on and claims priority under 35 U.S.C. § 119 to U.S. Provisional Application No. 63/141,620, filed Jan. 26, 2021, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an endoscope treatment device inserted into a body and used to ligate a tissue, and more particularly, to such an endoscope treatment device with an improved clip unit. 
     DESCRIPTION OF THE RELATED ART 
     Various endoscope treatment devices have been known. One such device is a ligation device which includes a clip unit and is used to ligate openings formed in tissues or blood vessels. A conventional ligation device may include a clip unit, a treatment tool body and a connection structure configured to connect the treatment tool body to the clip unit. The clip unit is detachably mounted on a distal end of the treatment tool body. The clip unit may include a clip main body and a pressing tube which is configured to accommodate the clip main body. The clip main body includes a pair of arm portions and a middle portion disposed between proximal ends of the pair of arm portions and connecting the pair of arm portions. 
     The connection structure includes a hook portion disposed at the distal end of the treatment tool body. The middle portion of the clip unit is engaged with the hook portion of the connection structure. By this engagement, the clip unit is able to be advanced and retracted through the pressing tube by operating the treatment tool body. Also, the clip unit is rotatable around an axis of the pressing tube so as to adjust the positions of the pair of arm portions during the procedure of grasping the tissue. 
     However, the conventional connection structure between the clip unit and the treatment tool body is deficient in one or more ways. For example, the conventional connection structure lacks sufficient strength to ensure the rotating movement of the clip unit around the axis of the pressing tube when the clip unit is rotated. Also for example, the conventional connection structure lacks sufficient strength to ensure a linear movement of the clip unit in the axis direction of the pressing tube when the clip unit is pulled by a manipulation wire. As a result, the clip unit may unexpectedly come off the hook portion of the treatment tool body before the ligating procedure is successfully completed. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present disclosure is directed to an endoscope treatment device and clip unit, which substantially obviate one or more of the issues due to limitations and disadvantages found in conventional endoscope treatment devices and clip units. 
     An object of the present disclosure is to provide a clip device, which comprises a tube having an interior volume and at least one open end; a clip including a first arm portion and a second arm portion, and wherein the clip is configured to slidably move between a retracted position in which the first and second arm portions are within the interior volume of the tube and a deployed position in which the first and second arm portions protrude from the open end of the tube; and an engagement mechanism disposed inside the tube and including a stepped connector and a hooking structure, wherein the engagement mechanism is configured to connect to the clip. The stepped connector includes an engaging region connecting two side regions, wherein a width of the engaging region of the stepped connector is smaller than a width of a first of the two side regions of the stepped connector. The hooking structure includes two lateral surfaces connected by a hook surface. A surface of the engaging region of the stepped connector engages with the hook surface of the hooking structure and each of the two side regions of the stepped connector are adjacent to respective one of the two lateral surfaces of the hooking structure. 
     Another object of the present disclosure is to provide an endoscope treatment device for ligaturing a living tissue, which comprises: a clip unit including first and second arm portions; and a pressing tube which is formed to be capable of accommodating the first and second are portions to make a distal end of the first arm portion and a distal end of the second arm portion approaching to each other; a linear member connected to the dip unit and provided to advance and retract the clip unit; a sheath in which the linear member is inserted so that the linear member is advanceable and retractable. The clip unit further includes an engagement mechanism disposed inside the tube and including a stepped connector and a hooking structure, wherein the engagement mechanism is configured to connect to the clip. The stepped connector includes an engaging region connecting two side regions, wherein a width of the engaging region of the stepped connector is smaller than a width of a first of the two side regions of the stepped connector. The hooking structure includes two lateral surfaces connected by a hook surface. A surface of the engaging region of the stepped connector engages with the hook surface of the hooking structure and each of the two side regions of the stepped connector are adjacent to respective one of the two lateral surfaces of the hooking structure. 
     Additionally, the engagement mechanism can have varying forms. In one embodiment, the stepped connector is part of the clip, and the hooking structure is connected to a manipulating line. In another embodiment, the hooking structure is part of the clip, and the stepped connector is connected to the manipulating line. In still another embodiment, the engagement mechanism includes two hooking structures, each with two lateral surfaces connected by a hook surface, and the stepped connector includes surfaces associated with two stepped connectors, each with an engaging region and two side regions, and the various features of the hooking structures and stepped connector function in a similar manner as for corresponding features in the single feature embodiments. 
     Additional features and advantages will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the disclosed an endoscope treatment device and clip unit will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The following detailed description of preferred embodiments can be read in connection with the accompanying drawings in which like numerals designate like elements and in which: 
         FIG. 1  is a sectional view (by cutting away a part of a side surface of the endoscope treatment device) schematically showing an endoscope treatment device in which a clip unit according to an exemplary embodiment is used. 
         FIG. 2  is a top sectional view schematically showing the distal end of the endoscope treatment device in  FIG. 1 . 
         FIG. 3  is a side sectional view showing a clip unit in  FIG. 1 . 
         FIG. 4  is a side sectional view showing the proximal end of the endoscope treatment device in  FIG. 1 . 
         FIG. 5  is a top sectional view showing the proximal end of the endoscope treatment device in  FIG. 1 . 
         FIG. 6  a schematic perspective view taken along the cutting line A 1 -A 1  in  FIG. 3 . 
         FIG. 7  is a diagram schematically showing a state of the clip unit in  FIG. 1  when viewed from the proximal end side. 
         FIG. 8  is a diagram taken along the cutting line A 2 -A 2  in  FIG. 4   
         FIG. 9A  is an enlarged side view illustrating an exemplary configuration of an embodiment of engagement mechanism between a clip and a connection member, and  FIG. 9B  is a schematically, representational cross-sectional view taken from line A 3 -A 3  of  FIG. 9A . 
         FIG. 10A  is a perspective view schematically illustrating an exemplary configuration of another embodiment of an engagement mechanism between a clip and a connection member,  FIG. 10B  is an enlarged view of region E in  FIG. 10A ,  FIG. 10C  is a schematic, representational cross-sectional view illustrating the engagement mechanism of the clip and the connection member of  FIG. 10A , and  FIG. 10D  is a schematic, representational side view illustrating the engagement mechanism. 
         FIG. 11A  is a perspective view schematically illustrating a clip and a connection member according to another embodiment,  FIG. 11B  is a side view of  FIG. 11A ,  FIG. 11C  is a schematic, representational cross-sectional view illustrating the engagement mechanism of the clip and the connection member of  FIG. 11A , and  FIG. 11D  is a schematic, representational side view schematically illustrating the engagement mechanism. 
         FIG. 12  is a schematic diagram showing an example usage of the endoscope treatment device in  FIG. 1 . 
         FIG. 13  is a schematic diagram showing an amount of power necessary to pull back a slider with respect to a movement amount by which the slider is pulled back in the endoscope treatment device in  FIG. 1 . 
         FIG. 14  is a side sectional view schematically showing the endoscope treatment device when the clip unit in  FIG. 1  is in a contact state. 
         FIG. 15  is a top sectional view schematically showing the endoscope treatment device when the clip unit in  FIG. 1  is in the contact state. 
         FIG. 16  is a side sectional view schematically showing the endoscope treatment device when the clip unit in  FIG. 1  is in an overpass state. 
         FIG. 17  is a top sectional view schematically showing the endoscope treatment device when the clip unit in  FIG. 1  is in the overpass state. 
         FIG. 18  is a schematic diagram of the clip unit in  FIG. 1  in the overpass state when viewed from the proximal end side. 
         FIG. 19  is side sectional view schematically showing the endoscope treatment device when the clip unit in  FIG. 1  is in a locking state. 
         FIG. 20  is top sectional view schematically showing the endoscope treatment device when the clip unit in  FIG. 1  is in the locking state. 
         FIG. 21  is a schematic diagram showing the clip unit in  FIG. 1  in the locking state when viewed from the proximal end side. 
         FIG. 22  is a schematic diagram showing another example usage of the endoscope treatment device in  FIG. 1 . 
         FIG. 23  is a schematic diagram showing still another example usage of using the endoscope treatment device in  FIG. 1 . 
     
    
    
     For ease of viewing, in some instances only some of the named features in the figures are labeled with reference numerals. 
     DETAILED DESCRIPTION 
     Hereinafter, accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments of the invention, and together with the general description given above and the detailed description of the exemplary embodiments given below, serve to explain the principles of the invention. Throughout all of the drawings, ratios of the thicknesses or dimensions of respective constituent elements are appropriately adjusted for clarity. 
     Also, it should be noted that references throughout this disclosure to the terms “distal” and “distally” are to a direction away from a manipulation portion  100  (see  FIG. 1 ), while references to the terms “proximal” and “proximally” are to a direction towards the manipulation portion  100 . 
       FIGS. 1 and 2  show an endoscope treatment device  1  as a ligation tool and includes a clip unit (hereinafter also abbreviated as a “clip”)  10  and a treatment device body  40 . The clip  10  can be detachably mounted on a distal end of the treatment device body  40 .  FIGS. 1 and 2  are sectional views passing through an axial line C 1  of a pressing tube  31  to be described below. 
       FIG. 3  is a sectional view showing the clip  10  of the endoscope treatment device  1 .  FIG. 4  is a sectional view showing a proximal end of the endoscope treatment device  1 .  FIG. 5  is a sectional view showing the proximal end of the endoscope treatment device  1 . Hereinafter, configurations and operations will be described with reference to the schematic drawings and main portions will be described with reference to the detailed drawings. 
     (Configuration: Arm Portions  12  and  13  of the Clip  10 ) 
     As shown in  FIGS. 1 and 2 , the clip  10  includes a clip main body  11 , a pressing tube  31 , and a helical spring (elastic member)  36 . The pressing tube  31  is formed in a cylindrical shape, but other tube shapes can be used, including those having cross-sections in the shape of an oval or in the shape of a polygon having n-sides, where n can be equal to or greater than 4. The pressing tube  31  has an interior volume and at least one open end to accommodate the insertion of the proximal end of the clip main body  11 . The helical spring  36  is accommodated inside the pressing tube  31 . The members forming the clip  10  in addition to the clip main body  11  are formed, for example, of a material such as a cobalt-chromium alloy, titanium, or stainless steel. The clip  10  is configured to be capable of being observed by MRI (Magnetic Resonance Imaging) radioscopy. 
     The clip main body  11  includes a first arm portion  12 , a second arm portion  13 , and a middle portion  14 . The first arm portion  12  and the second arm portion  13  are disposed to extend from the proximal end side to the distal end side of the clip main body  11  and face each other. The middle portion  14  is disposed to be located between a proximal end of the first arm portion  12  and a proximal end of the second arm portion  13 , and serves as a connection portion to connect the first arm portion  12  to the second arm portion  13 . Moreover, the clip main body is configured to slidably move between a retracted position, e.g., toward the proximal end of the pressing tube  31 , in which the arm portions  12  and  13  are within the interior volume of the pressing tube  31  and a deployed position, e.g., toward the distal end of the pressing tube  31 , in which the arm portions  12  and  13  protrude from the open end of the pressing tube  31 . 
     The first arm portion  12  and the second arm portion  13  are formed to be mutually separated in a natural state from the proximal end side to the distal end side. A claw  12   a  extending toward a side of the second arm portion  13  is formed at a distal end of the first arm portion  12 . A claw  13   a  extending toward a side of the first arm portion  12  is formed at a distal end of the second arm portion  13 . 
       FIG. 6  is a schematic perspective view taken along the cutting line A 1 -A 1  in  FIG. 3 . As shown in  FIG. 6 , in the second arm portion  13 , a cross-sectional shape orthogonal to a longitudinal direction on the distal end side thereof is formed as an arc-like round shape. More specifically, a middle portion of the outside surface of the arm portion  13  in an orthogonal direction Z to be described below is formed in a curved shape that is convex toward the outside. A similar shape is present for arm portion  12 . 
     Thus, for the first arm portion  12  and the second arm portion  13 , the strength against bending is improved and frictional resistance to a sheath tube  50  to be described below is reduced, so that advancement and retraction operations can smoothly be performed. 
     (Configuration: First Locked Portions  16  and  17  of Clip  10 ) 
     Here, as shown in  FIG. 1 , an axis X in which the first arm portion  12  and the second arm portion  13  face each other, an axis Y parallel to an axial line C 1  of the pressing tube  31 , and an axis Z orthogonal to each of the axis X and the axis Y are defined. As shown in  FIG. 2 , two first locked portions  16  and  17  are provided at the proximal end of the first arm portion  12 . The first locked portions  16  and  17  are provided to protrude from a lateral surface of the first arm portion  12  in the axis Z on a criterion plane S 1  parallel to the axial line (central axial line) C 1  of the pressing tube  31 . The first locked portions  16  and  17  protrude in opposite directions. 
       FIG. 2  is a diagram of the endoscope treatment device in  FIG. 1  when viewed in a direction orthogonal to the criterion plane S 1 . As shown in  FIG. 2 , the first locked portions  16  and  17  are formed to be line-symmetric with respect to the axial line C 1 . 
     As shown in  FIG. 2 , a proximal end surface  16   a  of the first locked portion  16  is formed to be separated and inclined from the first arm portion  12  (central axial line C 1 ) toward the distal end side of the first locked portion  16 . A distal end surface  16   b  of the first locked portion  16  is orthogonal to the axis Y. A proximal end surface  17   a  and a distal end surface  17   b  of the first locked portion  17  are formed to be line-symmetric to the proximal end surface  16   a  and the distal end surface  16   b  of the first locked portion  16  with respect to the axial line C 1 , respectively. 
     (Configuration: Protrusion Portions  18  and  19  of Clip  10 ) 
     As shown in  FIGS. 1 and 2 , two protrusion portions  18  and  19  are provided more distal than the first locked portions  16  and  17  in the first arm portion  12 . The protrusion portions  18  and  19  protrude from the lateral surface of the first arm portion  12  in the axis Z. The protrusion portions  18  and  19  are formed to be line-symmetric with respect to the axial line C 1 . Lengths of the protrusion portions  18  and  19  protruding from the first arm portion  12  in the axis Z are longer than the first locked portions  16  and  17  which protrude from the first arm portion  12  in the axis Z. 
     (Configuration: Arm Portion  13  of Clip  10 ) 
     As shown in  FIG. 1 , the claw  13   a  extending toward the side of the first arm portion  12  is formed at the distal end of the second arm portion  13 . In the second arm portion  13 , second locked portions  21 ,  22  and protrusion portions  23 ,  24  are formed like the first locked portions  16 ,  17  and the protrusion portions  18 ,  19  of the first arm portion  12 , respectively (the second locked portion  22  is referred to in  FIG. 7  and the protrusion portion  24  is not shown). That is, the second locked portions  21  and  22  protrude from the lateral surface of the second arm portion  13  in the axis Z. The protrusion portions  23  and  24  are provided to protrude from the lateral surface of the second arm portion  13  in the axis Z more distal than the second locked portions  21  and  22  in the second arm portion  13 . The second locked portions  21 ,  22  and the protrusion portions  23 ,  24  are disposed to be parallel to the first locked portions  16 ,  17  and the protrusion portions  18 ,  19  in the axis Z, respectively. That is, in  FIG. 2 , the first locked portions  16  and  17  overlap the second locked portions  21  and  22  and the protrusion portions  18  and  19  overlap the protrusion portions  23  and  24 . 
     In a side view shown in  FIG. 1 , the first arm portion  12  and the second arm portion  13  are formed at positions which are line-symmetric with respect to the axial line C 1 . 
     For the clip main body  11 , a plate formed for example, of a cobalt-chromium alloy or the like is punched in a shape in which the arm portions  12  and  13 , the middle portion  14 , the first locked portions  16  and  17 , the second locked portions  21  and  22 , and the protrusion portions  18 ,  19 ,  23 , and  24  are spread in a planar form. Then, the punched member is integrally formed in a C shape in a side view by bending a connection portion of the first arm portion  12  and the middle portion  14  and a connection portion of the second arm portion  13  and the middle portion  14 . 
     (Configuration: Connection Member  63 ) 
     The connection member  63  includes a hooking structure  77  at the distal end of a bridge  76 , and a through hole  76   a  is formed at the proximal end of the bridge  76 . A surface  76   b  (see  FIG. 2 ) is formed facing an hook surface of the hooking structure  77 . The surface  76   b  may also be an inclination surface as shown in  FIG. 2  with respect to the axial line C 1 , or as shown in  FIG. 9A , may be a surface extending upwardly in a direction orthogonal to the axial line C 1 . 
     When a turned portion of a wire  73   a  of a loop portion  73  is inserted into the through hole  76   a , the connection member  63  is connected to the loop portion  73  to be rotatable about an axis parallel to the axis X (rotatable in an arrow direction D in  FIG. 2 ). 
     The width of the connection member  63  is the outer diameter of the bridge  76  in a direction orthogonal to the central axial line C 1  when the hooking structure  77  is disposed on the distal end side of the bridge  76 . The width of the connection member  63  is slightly less than the inner diameter of a helical spring  36 , the inner diameter of a coil sheath  66 , and the inner diameter of a distal end member  67 . 
     By disposing the middle portion  14  between the hooking structure  77  of the connection member  63  and the surface  76   b  of the connection member  63 , the hooking structure  77  can engage with the middle portion  14 . 
     (Configuration: Engagement Portion Between Clip  10  and Connection Member  63 ) 
     First Embodiment 
       FIG. 9A  is an enlarged side view illustrating an exemplary configuration of an engagement mechanism between the clip  10  and a connection member  63 , and  FIG. 9B  is a cross-sectional view taken from line A 3 -A 3  of  FIG. 9A . As shown in  FIG. 9A , the engagement mechanism includes the hooking structure  77  and an engaging portion  15  (also referred to as a stepped connector). The stepped connector  15  includes an engaging region ER configured to engage with a hook surface  79  (see  FIG. 10B ) of the hooking structure  77  and two side regions SR arranged adjacent to two lateral surfaces  78  of the hooking structure  77  (see  FIG. 9B ). The two lateral surfaces  78  and the hook surface  79  are located on a distal end portion of the hooking structure  77 , and the bridge  76  includes a first end connected to the distal end portion of the hooking structure  77  and extending therefore to form part of a recess RR of the connection member  63 . The engaging region ER is on the middle portion  14  of the clip  10 , and the two side regions SR are on the proximal ends of the arm portion  12  and the arm portion  13  of the clip  10 . 
     The engaging region ER has a width W 1  extending in the axis Z and in a direction orthogonal to the axial line C 1  in  FIG. 2 , the two side regions SR of the arm portions  12  and  13  each have a width W 2  also extending in the axis Z and in a direction orthogonal to the axial line C 1  in  FIG. 2 , and a bridge  76  of the connection member  63  has a width W 3  also extending in the axis Z and in a direction orthogonal to the axial line C 1  in  FIG. 2 . The relationships among the widths W 1 , W 2  and W 3  may be set such that the width W 2  is greater than the width W 1 , and preferably, 1.5 times or up to 2 times greater than the width W 1 . The width W 1  may be set to be substantially the same as the width W 3 . Moreover, the two side regions SR may have a first width on the arm portion  12  side and a second width on the arm portion  13  side, and the first width is different from the second width, i.e. have different lengths. However, the width W 1  is smaller than either the first width or the second width of the two side regions SR. In other words, each of the first width and the second width is greater than the width W 1  and preferably is 1.5 times to 2 times greater than the width W 1 . 
     The stepped portion  15  also includes a first seating surface  80  and a second seating surface  81 . The first seating surface  80  may be part of a bottom surface of the middle portion  14 , and the second seating surface  81  may be part of a proximal end surface of the arm portion  12 . The stepped portion  15  has an angle α that is formed by the first seating surface  80  and the second seating surface  81 . The angle α may be a right angle (90 degrees) or an obtuse angle (greater than 90 degrees to 180 degrees). The first seating surface  80  may seat on (or be in contact with) an upper surface  76   c  of the bridge  76 . 
     While not shown, a stepped portion that is formed by the arm portion  13  and the middle portion  14  may have the same configuration as the stepped portion  15 . The stepped portion also includes one region where the middle portion  14  contacts the hooking structure  77  and the other region where the arm portion  13  is adjacent to the hooking structure  77 . The two regions may have the same configuration as the engaging region ER and the two side regions SR, respectively. The stepped portion may also include two seating surfaces that may have the same configuration as the first and second seating surfaces S 1  and S 2 . One of the two seating surfaces may be part of a proximal end surface of the arm portion  13 , and the other seating surface may be part of a bottom surface of the middle portion  14 . The not-shown stepped portion may also have the same angle α that is formed by the two seating surfaces, one of which may be in contact with the upper surface  76   c  of the bridge  76 . 
     As shown in  FIG. 13 , which will be described in detail later, when the clip  10  is strongly pulled back toward the proximal end by the hooking structure  77 , the bridge  76 , which is connected to and supports the hooking portion, has to bear a strong pulling force coming from the manipulation portion  100 . If the width W 3  of the bridge  76  is too narrow with respect to the width W 1  of the region R 1 , the strength of the connection member  63  in its axis direction becomes weak, thereby causing deformation of the hooking structure  77 . As a result, the arm portions  12  and  13  of the clip  10  may come off the hooking structure  77  due to the deformation before the claws  12   a  and  13   a  of the clip  10  successfully grasp a target tissue. By increasing the width W 3  to be substantially the same as the width W 1 , the strength of the bridge  76  can be increased in the axis direction. Thus, when the clip  10  is pulled back toward the proximal end by the hooking structure  77 , the clip  10  can be prevented from coming off the connection member  63  before the completion of the grasping operation. 
     On the other hand, the clip  10  may be rotatable inside the pressing tube  31  by rotating the hooking structure  77  around the axis direction of the connection member  63 . In order to prevent the arm portions  12  and  13  from coming off the hooking structure  77  inside the pressing tube  31  when the hooking structure  77  is rotated, it is necessary to strengthen the connection structure between the clip  10  and the connection member  63  in the rotation direction. In this exemplary embodiment, the region R 2  between the arm portions  12  and  13  and the hooking structure  77  is larger than the contact region R 1  by setting the width W 2  to be greater than the width W 1  and preferably to be 1.5 times to 2 times greater than the width W 1 . As shown in  FIG. 9B , the arm portions  12  and  13  overlap with the entire sides  78  of the hooking structure  77  in a side view seen from the axis Y except for a top  77   a  of the hooking structure  77 . With this exemplary configuration, the strength of the connection structure in the rotation direction can be increased by providing more available contact area. Thus, the clip  10  can be prevented from coming off the connection member  63  when the connection member  63  is rotated before the completion of the grasping operation. 
     Second Embodiment 
       FIG. 10A  is a perspective view schematically illustrating a clip  10 ′ and a connection member  63 ′ according to a second exemplary embodiment, and  FIG. 10B  is an enlarged view of region E in  FIG. 10A . As shown in  FIGS. 10A and 10B , different from the first exemplary embodiment, the engagement mechanism of the second exemplary embodiment includes first and second hooking structures  77   a  and  77   b  and first and second stepped connectors  15   a  and  15   b . In this exemplary embodiment, each of the first and second hooking structures  77   a  and  77   b  may be the same as the hooking structure  77  described in the first embodiment. That is, the first hooking structure  77   a  includes the two lateral surfaces  78  connected by the hook surface  79 , and the second hooking structure  15   b  includes the two lateral surfaces  78  connected by the hook surface  79 . Also, each of the first and second stepped connectors  15   a  and  15   b  may be the same as the stepped connector  15  described in the first embodiment. That is, the first stepped connector  15   a  includes an engaging region ER and two side regions SR, and the second stepped connector  15   b  includes an engaging region ER and two side regions SR. Thus, the engaging region of the first stepped connector engages with the hook surface of the first hooking structure, and each of the two side regions of the first stepped connector are adjacent to a respective one of the two lateral surfaces of the first hooking structure. The engaging region of the second stepped connector engages with the hook surface of the second hooking structure, and each of the two side regions of the second stepped connector are adjacent to a respective one of the two lateral surfaces of the second hooking structure. However, the first and second hooking structures  77   a  and  77   b  may have different configurations from each other, and the first and second stepped connectors  15   a  and  15   b  may also have different configurations from each other. 
     Also, in the engagement mechanism of the second exemplary embodiment, the first and second stepped connectors  15   a  and  15   b  are formed at the proximal end of each of the arm portions  12 ′ and  13 ′, and the first and second hooking structures  77   a  and  77   b  are formed at the distal end of the connection member  63 ′. The first and second stepped connector  15   a  and  15   b  are configured to be line-symmetric along the axial line C 1  in a side view, the first and second hooking structures  77   a  and  77   b  are configured to be line-symmetric along the axial line C 1  in the side view, and two corresponding bridges  76   a  and  76   b  are configured to be line-symmetric along the axial line C 1  in the side view. 
     In this exemplary embodiment, the width relationships among the first and second stepped connectors  15   a  and  15   b  and the bridges  76   a  and  76   b  are also the same as those described in the first exemplary embodiment. 
       FIG. 10C  is a cross-sectional view schematically illustrating the engagement mechanism of the clip  10 ′ and the connection member  63 ′, and  FIG. 10D  is another schematic, representational cross-sectional view illustrating the engagement mechanism of the clip  10 ′ and the connection member  63 ′. Compared to the first exemplary embodiment, the second exemplary embodiment using a configuration of double-stepped connectors and double-hooking structures, which can provide a more stable engagement between the clip  10 ′ and the connection member  63 ′. 
     Third Embodiment 
       FIG. 11A  is a perspective view schematically illustrating a clip  10 ″ and a connection member  63 ″ according to a third exemplary embodiment, and  FIG. 11B  is a schematic, representational cross-sectional view of  FIG. 11A . As shown in  FIGS. 11A and 11B , different from the first exemplary embodiment, the engagement mechanism in the third exemplary embodiment is configured to have a hooking structure  77 ″ extended from the arm portions  12 ″ and  13 ″ (or integrally formed with the arm portions  12 ″ and  13 ″), and the connection member  64 ″ that is hooked on the hooking structure  77 ″. The connection member  64 ″ is configured to have a stepped connector  15 ″ formed by two arm portions  81  and  82  and a middle portion  83 . The middle portion  83  is also referred to as a connection portion that connects the arm portion  81  to the arm portion  82 . Thus, in the third exemplary embodiment, the connection member  64 ″ having the stepped connector  15 ″ is hooked on the hooking structure  77 ″ that is attached to the clip  10 ″. 
     The hooking structure  77 ″ may be attached to the clip  10 ″ by welding or the like. 
       FIG. 11C  is a cross-sectional view schematically illustrating the engagement mechanism between the clip  10 ″ and the connection member  63 ″, and  FIG. 11D  is another schematic, representational cross-sectional view illustrating the engagement between the clip  10 ″ and the connection member  63 ″. Different from the first exemplary embodiment, in the third exemplary embodiment, the hooking structure  77 ″ is part of the clip  10 ″ and is formed on the distal end (connection portion  14 ″) of the clip  10 ″, and the stepped connector  15 ″ is part of the connection member  63 ″ and located at the distal end of the connection member  63 ″. The proximal end of the connector member  63 ″ is connected to a linear member  74  (in  FIG. 1 ). 
     (Configuration: Locking Portion  32  of Clip  10 ) 
     As shown in  FIGS. 2 and 7 , on the inner circumferential surface of the proximal end of the pressing tube  31 , a locking portion  32  protrudes over the entire inner circumference surface. When viewed in the direction of axis Y shown in  FIG. 7 , an edge  32   a  of the locking portion  32  on a side of the axial line C 1  is formed in a circular shape that is coaxial with the pressing tube  31 . As shown in  FIG. 2 , a proximal end surface  32   b  (proximal-end-side end surface) and a distal end surface  32   c  (distal-end-side end surface) of the locking portion  32  are orthogonal to the axis Y. 
     Portions on the proximal end side of the protrusion portions  18  and  19  in the first arm portion  12 , portions on the proximal end side of the protrusion portions  23  and  24  in the second arm portion  13 , and the middle portion  14  can be inserted into the locking portion  32 . As shown in  FIG. 7 , a length L 1  between an end of the first locked portion  16  and an end of the first locked portion  17  in the axis Z is less than the inner diameter of the locking portion  32 . In an initial state to be described below, parts of the first locked portions  16  and  17  are set to overlap the locking portion  32  when viewed along the axis Y. That is, in the state shown in  FIG. 7 , the edge  32   a  is set such that the length L 1  of the first locked portions  16  and  17  is longer than a height (a length of a line segment between positions P 1  and P 2  in  FIG. 7 ) of the edge  32   a  in which the first locked portions  16  and  17  face each other at the positions P 1  and P 2 . 
     As shown in  FIG. 2 , a tapered surface  31   a  is formed over the entire inner circumference surface at the distal end of the pressing tube  31 . The diameter of the tapered surface  31   a  expands toward the distal end side of the pressing tube. 
     The pressing tube  31  and the locking portion  32  are integrally formed of a material such as, for example, a  64  titanium alloy (Ti-6AL-4V) or a cobalt-chromium alloy. 
     (Configuration: Helical Spring  36  of Clip  10 ) 
     As shown in  FIG. 3 , an end turn portion  36   b  is provided at the distal end of the helical spring  36 . The inner diameter of the formed end turn portion  36   b  is less than that of the other portions of the helical spring  36 . 
     When the helical spring  36  is accommodated inside the pressing tube  31 , the distal end thereof interlocks with the protrusion portions  18 ,  19 ,  23 , and  24  and the proximal end thereof interlocks with the locking portion  32 . The proximal end of the helical spring  36  and the locking portion  32  may be fixed by welding or the like. 
     The portions on the proximal end side of the protrusion portions  18  and  19  in the first arm portion  12 , the portions on the proximal end side of the protrusion portions  23  and  24  in the second arm portion  13 , and the middle portion  14  can be inserted into the helical spring  36 . When the protrusion portions  18 ,  19 ,  23 , and  24  are moved toward the proximal end side, the protrusion portions  18 ,  19 ,  23 , and  24  interlock with the end turn portion  36   b  of the helical spring  36 . Even when the helical spring  36  does not include the end turn portion  36   b , the same advantage can be obtained by using a separate member such as a washer at the distal end of the helical spring  36 . 
     In the initial state of the clip  10  shown in  FIGS. 1 and 2 , the proximal end of the first arm portion  12 , the proximal end of the second arm portion  13 , and the middle portion  14  are located at the distal end side with respect to the locking portion  32  inside the pressing tube  31 . The first locked portions  16  and  17  and the second locked portions  21  and  22  do not come into contact with the locking portion  32  of the pressing tube  31 . Wires  36   a  of the helical spring  36  adjacent to each other in the axis Y are separated from each other. The helical spring  36  is compressed in the axis Y slightly more than in the natural state. The distal end of the first arm portion  12  and the distal end of the second arm portion  13  of the clip main body  11  are separated from each other so as to be in an opened state. 
     (Configuration: Relation Between Clip Main Body  11  of Clip  10  and Pressing Tube  31 ) 
     In the clip  10  with the above-described configuration, the first arm portion  12  and the second arm portion  13  are separated in the axis X in the initial state. Therefore, as shown in  FIG. 7 , when the first locked portion  16  is viewed from the proximal end side, the first locked portion  16  is overlapped by a portion of the edge  32   a  at the position P 1  of the locking portion  32 . That is, when first arm portion  12  is moved toward the proximal end side with respect to the pressing tube  31 , the first locked portion  16  comes into contact with the portion of the edge  32   a  at the position P 1 . The portion of the edge  32   a  at the position P 1  comes into point contact with the first locked portion  16 . 
     Likewise, when the first arm portion  12  is moved toward the proximal end side with respect to the pressing tube  31 , the first locked portion  17  comes into contact with the portion of the edge  32   a  at the position P 2 . A part of the edge  32   a  at the position P 2  comes into point contact with the first locked portion  17 . A proximal end surface  16   a  of the first locked portion  16  comes into contact with the portion of the edge  32   a  at the position P 1 . A proximal end surface  17   a  of the first locked portion  17  comes into contact with the portion thereof at the position P 2 . 
     Positions of the edge  32   a  corresponding to the positions P 1  and P 2  are indicated by positions Q 1  and Q 2  in  FIG. 2 . 
     When the second arm portion  13  integrally formed with the first arm portion  12  is moved toward the proximal end side with respect to the pressing tube  31 , the second locked portions  21  and  22  come into contact with the locking portion  32  of the pressing tube  31 , like the first locked portions  16  and  17  of the first arm portion  12 . 
     (Configuration: Treatment Device Body  40 ) 
     Next, the configuration of the treatment device body  40  will be described. 
     As shown in  FIGS. 1 and 2 , the treatment device body  40  includes the sheath tube  50 , an insertion portion  60  and a manipulation portion  100 . The insertion portion  60  is inserted inside the sheath tube  50  to be advanceable and retractable. The manipulation portion  100  is attached to the proximal end of the insertion portion  60 . 
     The sheath tube  50  can be formed of, for example, a fluorine resin such as polytetrafluoroethylene (PTFE) or a resin material such as high-density polyethylene (HDPE). 
     (Configuration: Sheath Portion  61  of Treatment Device Body  40 ) 
     The insertion portion  60  includes a sheath portion  61  and a manipulation wire  62 . The manipulation wire  62  is inserted into the sheath portion  61  so as to be advanceable and retractable. The connection member  63  is connected to the distal end of the manipulation wire  62 . The connection member  63  is provided to be rotatable about an axis parallel to the axis X with respect to the manipulation wire  62 . 
     The sheath portion  61  includes a coil sheath  66  and a distal end member (stopper portion)  67  fixed to the distal end of the coil sheath  66 . The coil sheath  66  is formed, for example, of stainless steel with a high compression resistance such as SUS301 of JIS (Japanese Industrial Standards). 
     A coil formed by densely winding a wire (not shown) in the axis Y can be used as the coil sheath  66 . The coil sheath  66  has flexibility and is strong against a compressive force in the axis Y. The inner diameter of the coil sheath  66  is almost the same as the inner diameter of the helical spring  36 . 
     The distal end member  67  is formed of, for example, stainless steel in a cylindrical shape. The inner diameter of the distal end member  67  is less than the inner diameter of the coil sheath  66 . The outer diameter of the distal end member  67  is greater than that of the coil sheath  66  or the pressing tube  31 . A concave portion  67   a  is formed on the outer circumferential surface of the proximal end of the distal end member  67  by reducing the outer diameter thereof. When the distal end of the coil sheath  66  engages with the concave portion  67   a , the distal end member  67  and the coil sheath  66  are fixed together by laser welding or the like. 
     Thus, on the inner circumferential surface of the distal end of the sheath portion  61 , a stepped portion  68  is formed in a connection portion of the coil sheath  66  and the distal end member  67  by reducing the inner diameter of the distal end member  67  provided more distal than the coil sheath  66  with respect to the coil sheath  66 . The inner diameter of the distal end member  67  is formed so that the distal end member  67  does not engage with the first locked portions  16  and  17  and the second locked portions  21  and  22  when the clip  10  engages with the locking portion  32 , as will be described below. 
     (Configuration: Distal End Member  67  of Treatment Device Body  40 ) 
     A concave portion is formed over the entire inner circumferential surface of the distal end of the distal end member  67  and a support member  69  is disposed more distal than the concave portion. In this example, the support member  69  is formed in a cylindrical shape. The support member  69  has an inner diameter that is slightly greater than the outer diameter of the pressing tube  31  and has dimensions such that the proximal end of the pressing tube  31  can be accommodated therein. In the concave portion on the inner circumferential surface of the support member  69 , a surface facing forward is a distal end support surface (distal end surface)  67   b . The distal end support surface  67   b  can come into contact with the proximal end surface of the pressing tube  31 . The clip  10  is disposed on the distal end side of the sheath portion  61 . The support member  69  can support the outer circumferential surface of the pressing tube  31  coming into contact with the distal end support surface  67   b.    
     In this configuration, shaking of the clip  10  with respect to the support member  69  can be suppressed to be as small as possible, and thus an inclination of the clip  10  with respect to the support member  69  can be allowed to some extent. Therefore, the endoscope treatment device  1  can be inserted smoothly even into the bending shape of an endoscope channel or the like. 
     (Configuration: Manipulation Wire  62  of Treatment Device Body  40 ) 
     The manipulation wire  62  is formed of, for example, a single line mode of metal or a twisted line made of a metal. A loop portion  73  is provided at the distal end of the manipulation wire  62  via a diameter expansion portion  72 . A linear member  74  (see  FIG. 1 ) is formed by the manipulation wire  62  and the loop portion  73 . 
     The diameter expansion portion  72  is formed of, for example, a metal or the like in a cylindrical shape. The outer diameter of the diameter expansion portion  72  is less than the inner diameter of the coil sheath  66  and is greater than the inner diameter of the distal end member  67 . When the distal end surface of the diameter expansion portion  72  comes into contact with the stepped portion  68 , the protrusion amount of the loop portion  73  with respect to the sheath portion  61  is regulated up to a length L 2  (see  FIG. 22 ). The length L 2  is the maximum protrusion amount of the loop portion  73  allowed by the distal end member  67 . 
     The loop portion  73  is formed by turning back a wire  73   a . The wire  73   a  is turned back so that the turned portion is on the distal end side of the wire  73   a . Both ends of the wire  73   a  are fixed to the diameter expansion portion  72  by brazing, resistance welding, or the like. 
     (Configuration: Manipulation Portion  100  of Treatment Device Body  40 ) 
     As shown in  FIG. 1 , the manipulation portion  100  includes a manipulation portion main body  101 , a slider  102 , and a fracture mechanism  64 . The manipulation portion main body  101  is installed on the proximal end of the coil sheath  66 . The slider  102  is provided to be externally fitted to the manipulation portion main body  101  and to be slidable with respect to the manipulation portion main body  101  in the axis Y. The fracture mechanism  64  is connected to the proximal end of the manipulation wire  62  and the slider  102 . 
     The manipulation portion main body  101  is formed in a rod shape extending in the axis Y. A finger hooking portion  101   a  is attached to the proximal end of the manipulation portion main body  101 . On the proximal end side of the finger hooking portion  101   a , a planar portion  101   c  is provided so that the manipulation portion  100  can be easily grasped with two hands (see  FIG. 4 ). A slit  101   b  extending in the axis Y is formed in the manipulation portion main body  101 . 
     The slider  102  is formed in a cylindrical shape. On the outer circumferential surface of the slider  102 , a concave portion  102   a  is formed around the circumference. A pair of flange portions  102   b  and  102   c  are formed in the slider  102  in the axis Y so that the concave portion  102   a  is located between a pair of flange portions  102   b  and  102   c . The pair of flange portions  102   b  and  102   c  have elliptical shapes when viewed in the axis Y (see  FIGS. 4 and 8 ). Thus, the slider  102  can be easily grasped. When the manipulation portion  100  of the endoscope treatment device  1  is packed, space can be saved. As shown in  FIG. 5 , a groove  102   e  extending in the axis Z is formed in a tube hole  102   d  of the slider  102 . 
     When the slider  102  engages with the slit  101   b  of the manipulation portion main body  101 , the movement range of the slider  102  with respect to the manipulation portion main body  101  in the axis Y is regulated. The fracture mechanism  64  is disposed inside the tube hole  102   d  of the slider  102 , as shown in  FIGS. 4 and 5 . In other words, the fracture mechanism  64  is built in the manipulation portion  100 . 
     (Operation of Treatment Device Body  40 ) 
     Next, an operation of the treatment device body  40  will be described. 
     In the above-described configuration, by sliding the slider  102  in the axis Y with respect to the manipulation portion main body  101 , the manipulation wire  62  can be manipulated to be advanced and retracted in the axis Y, thereby advancing and retracting the clip  10  with respect to the pressing tube  31 . 
     (Action: Initial State) 
     Next, a technique used to ligate a target tissue with the clip  10  of the endoscope treatment device  1  with the above-described configuration will be described. 
     When the endoscope treatment device  1  is provided to a user who is an operator, as shown in  FIG. 12 , the sheath tube  50  is pushed to the insertion portion  60  so that the clip  10  installed in the treatment device body  40  is hidden. The helical spring  36  of the clip  10  in the initial state is compressed in the axis Y slightly more than in the natural state. Therefore, the proximal end surface of the pressing tube  31  comes into contact with the distal end support surface  67   b . The distal end surface of the diameter expansion portion  72  comes into contact with the stepped portion  68  and the loop portion  73  protrudes up to the maximum protrusion amount from the distal end member  67 . 
     When the endoscope treatment device  1  is used, an endoscope insertion portion of an endoscope (not shown) is inserted into the body of a patient. The sheath tube  50  of the endoscope treatment device  1  is inserted from the proximal end of a channel of the endoscope and the sheath tube  50  protrudes from the distal end of the channel of the endoscope. When the sheath tube  50  is pulled back with respect to the insertion portion  60 , the clip  10  protrudes from the distal end side of the sheath tube  50 , as shown in  FIG. 1 . Thus, the arm portions  12  and  13  of the clip  10  enter an opened state shown in  FIG. 1 . 
       FIG. 13  is a schematic diagram showing the amount of power necessary to pull back the slider with respect to the movement amount by which the slider is pulled back in the endoscope treatment device. The slider  102  is moved (pulled back) toward the proximal end side with respect to the manipulation portion main body  101  from the initial state shown in  FIG. 1 . The clip  10  is configured such that the amount of power necessary to pull back the slide  102  changes with this movement, as shown in  FIG. 13 . In  FIG. 13 , a relative change in the amount of power necessary to pull back the slider in various states such as the initial state of the clip  10  are shown. 
     The state of the clip  10  is changed from the initial state to a contact state to an overpass state and then to a locking state as an operation of pulling back the slider  102 . Hereinafter, the change in the amount of power and the change in the state of the clip  10  will be described in detail. 
     In the initial state, for example, the diameter expansion portion  72  comes into contact with the stepped portion  68 . Thus, the proximal end surface of the pressing tube  31  comes into contact with the distal end support surface  67   b , and the pressing tube  31  and the distal end support surface  67   b  are not separated over at least the depth of the support member  69  in the longitudinal direction. 
     Next, the clip  10  is turned toward the target tissue T (referred to  FIG. 16 ) inside the body by performing a manipulation of curving a curving portion provided in the endoscope insertion portion while the inside of the body is examined with the endoscope. By pushing the endoscope treatment device  1  in the endoscope, the arm portions  12  and  13  are pressed against the target tissue T. 
     When the user grasps the manipulation portion  100  and pulls back the slider  102 , the first arm portion  12  and the second arm portion  13  are urged toward the inner circumferential surface of the distal end of the pressing tube  31 . As a result, the first arm portion  12  is elastically deformed on the side of the second arm portion  13  and the second arm portion  13  is elastically deformed on the side of the first arm portion  12 , and thus the distal end of the first arm portion  12  approaches the distal end of the second arm portion  13  (the arm portions  12  and  13  are closed). The helical spring  36  is gradually compressed in the axis Y. 
     The amount of power by which the slider  102  is pulled back is transmitted to the fracture mechanism  64 . 
     (Action: Contact State from Initial State) 
     When the slider  102  is pulled further back, as shown in  FIGS. 7, 14, and 15 , the first locked portions  16  and  17  and the second locked portions  21  and  22  enter the contact state with the locking portion  32  of the pressing tube  31 . At this time, as shown in  FIG. 7 , the first locked portion  16  and the first locked portion  17  come into contact with the edge  32   a  of the pressing tube  31  at the position P 1  and the position P 2 , respectively. 
     In a region R 1  corresponding to the initial state to the contact state, as shown in  FIG. 13 , the amount of power necessary to pull back the slider  102  increases as the slider  102  is pulled back. The clip  10  is changed from the opened state to the closed state. Since the connection member  63  is disposed inside the pressing tube  31  or the sheath portion  61 , the connection member  63  is not rotated with respect to the loop portion  73  and the engagement of the hooking structure  77  and the middle portion  14  is maintained. Since the fracture mechanism  64  does not fracture, the amount of power by which the slider  102  is pulled back can be transmitted to the manipulation wire  62  via the fracture mechanism  64 . 
     When the slider  102  is pushed, the amount of power by which the slider  102  is pushed can be transmitted to the manipulation wire  62 . 
     (Action: Overpass State from Contact State) 
     Proximal end surfaces  16   a  and  17   a  of the first locked portions  16  and  17  are formed to be inclined, as described above. The edge  32   a  of the locking portion  32  has a circular shape. Therefore, when the slider  102  is pulled further back, the first locked portion  16  receives a perpendicular force from the edge  32   a  in parallel to a normal line N orthogonal to a tangent line θ of the edge  32   a  at the position P 1  at which the first locked portion  16  comes into contact with the edge  32   a  of the locking portion  32 , when viewed in the axis Y shown in  FIG. 18 . The perpendicular force moves the first locked portion  16  of the first arm portion  12  in the axis X so that the first locked portion  16  becomes closer to the second arm portion  13 . 
     When the pullback manipulation continues, as shown in  FIGS. 16 to 18 , the first locked portions  16  and  17  come into point contact with the locking portion  32  and the edge  32   a  of the locking portion  32  with which the first locked portion  16  comes into contact moves from the position P 1  to a position P 3 . Simultaneously, the edge  32   a  of the locking portion  32  with which the first locked portion  17  comes into contact moves from the position P 2  to a position P 4 .  FIGS. 16 to 18  illustrate the overpass state in which the distal end of the proximal end surface  16   a  of the first locked portion  16  and the distal end of the proximal end surface  17   a  of the first locked portion  17  come into contact with the edge  32   a  of the locking portion  32 . 
     Likewise, the second arm portion  13  receives the perpendicular force from the edge  32   a  of the locking portion  32  and moves in the axis X to become closer to the first arm portion  12 . At this time, the middle portion  14  is elastically deformed so that both ends of the middle portion  14  move toward the side of the axial line C 1 . 
     By rotating the manipulation wire  62  with respect to the sheath portion  61  in the initial state, the direction of the clip  10  can be adjusted. 
     In a region R 2  corresponding to the contact state to the overpass state, as shown in  FIG. 13 , there is an increase in the rate of the amount of power necessary to pull back the slider  102  per unit movement amount by which the slider  102  is pulled back (that is, the rate of increase is greater than in the above-described region R 1 ). In other words, while the change of the amount of power characteristic in which the gradient (slope) is relatively gentle is shown in the region R 1 , a change of the amount of power characteristic in which the gradient (slope) is relatively sharp is shown in the region R 2  in which the first locked portions  16  and  17  and the second locked portions  21  and  22  come into contact with the locking portion  32 . 
     That is, the user who pulls back the slider  102  feels that the slider  102  is abruptly heavier in the region R 2  than in the region R 1  when the user pulls back the slider  102 . Thus, the user can easily recognize whether a state in which the user is currently pulling back the slider  102  is in the region R 1  or the region R 2 , in other words, the user can easily recognize whether the slider  102  is being pulled beyond the contact state. 
     In the region R 2 , the closed state of the clip  10  is maintained. Since the connection member  63  is disposed inside the sheath portion  61 , the engagement of the hooking structure  77  and the middle portion  14  is maintained. The fracture mechanism  64  does not fracture. For example, an amount of power F 1  necessary to cause the clip  10  to enter the overpass state, as shown in  FIG. 13 , is in the range of about 20 N to about 50 N (newtons). 
     As shown in  FIG. 18 , in the overpass state, a distance between the positions P 3  and P 4  of the edge  32   a  is the same as the length L 1  of the first locked portions  16  and  17  described above. 
     (Action: Re-Gripping) 
     The clip  10  is elastically deformed. Therefore, when the slider  102  is pushed while the clip  10  is in any state in the regions R 1  and R 2 , the compressed helical spring  36  is stretched. When the pressing tube  31  comes into contact with the distal end support surface  67   b , the clip main body  11  is moved toward the distal end side with respect to the pressing tube  31  and the clip  10  enters the initial state shown in  FIG. 1 . For example, through the manipulation of the curving of the curving portion, the clip  10  is turned toward another target tissue T. Thereafter, by performing the steps in the above-described order, the target tissue T can be re-gripped with the clip  10 . 
     (Action: Locking State from Overpass State) 
     When the slider  102  is pulled further back from the overpass state, the positions of the first arm portion  12  and the second arm portion  13  with respect to the pressing tube  31  in the axis X and the axis Z are maintained. In this state, the first arm portion  12  provided with the first locked portions  16  and  17  and the second arm portion  13  provided with the second locked portions  21  and  22  are inserted inside the locking portion  32 . Then, the first locked portions  16  and  17  and the second locked portions  21  and  22  are moved toward the proximal end side beyond the locking portion  32 . 
     At this time, the arm portions  12  and  13  and the middle portion  14  are not urged from the locking portion  32 . Therefore, as shown in  FIGS. 19 to 21 , the proximal end side of the first arm portion  12  and the proximal end side of the second arm portion  13  are moved in the axis X by the elastic force of the middle portion  14  to be separated from each other. When a force for moving the clip main body  11  toward the proximal end side of the pressing tube  31  is released, the distal end surfaces  16   b  and  17   b  of the first locked portions  16  and  17  enter the locking state in which the distal end surfaces  16   b  and  17   b  are locked by the proximal end surface  32   b  of the locking portion  32  (that is, distal end surfaces  16   b  and  17   b  are held distally relative to the proximal end surface  32   b ). 
     In a region R 3  corresponding to the overpass state to the locking state, as shown in  FIG. 13 , a part of the elastic deformation of the arm portions  12  and  13  and the middle portion  14  is released. Thus, the amount of power necessary to pull back the slide  102  gradually decreases as the slider  102  is pulled back. In the region R 3 , the closed state of the clip  10  is maintained. Since the connection member  63  is disposed inside the sheath portion  61 , the engagement of the hooking structure  77  and the middle portion  14  is maintained. The fracture mechanism  64  does not fracture. 
     When the clip  10  enters the locking state, as shown in  FIGS. 19 and 20 , the wires  36   a  of the helical spring  36  compressed in the axis Y enter a close coiling state in which the wires  36   a  adjacent in the axis Y are almost touching. When the clip  10  enters the locking state, the distal end surfaces  16   b  and  17   b  of the first locked portions  16  and  17  interlock with the proximal end surface  32   b  of the locking portion  32 . Therefore, the movement of the clip main body  11  with respect to the pressing tube  31  toward the distal end side is regulated. That is, a state in which the clip  10  ligates the target tissue T is maintained and the state of the clip does not return to the initial state in which the arm portions  12  and  13  enter the opened state. The clip  10  is fixed in the state in which the arm portions  12  and  13  are closed. In the clip  10 , the middle portion  14  protrudes on the proximal end side with respect to the pressing tube  31 . 
     When the first locked portions  16  and  17  and the second locked portions  21  and  22  are moved toward the proximal end side beyond the locking portion  32 , the first locked portions  16  and  17  and the second locked portions  21  and  22  may pass over the locking portion  32  by scraping against the locking portion  32  or deforming the locking portion  32 . In this case, in order to prevent excessive breakage of the locking portion  32 , it is desirable to perform a chamfering process or the like on portions in which the first locked portions  16  and  17  and the second locked portions  21  and  22  come into contact with the locking portion  32 . 
     (Action: Immediately Before Fracture State) 
     Since the helical spring  36  is in the compressed state, the clip main body  11  may not be moved toward the proximal end side with respect to the pressing tube  31  even if the slider  102  is pulled further back. The locking state of the clip  10  is maintained and not changed. However, when the slider  102  is pulled back, a tensile force acting on the fracture mechanism  64 , the manipulation wire  62 , or the like gradually increases. In a region R 4  shown in  FIG. 13 , i.e., the region R 4  corresponding to the locking state to a state immediately before a fracture state of the fracture mechanism  64  to be described below, as shown in  FIG. 13 , the closed state of the clip  10  is maintained. Since the connection member  63  is disposed inside the sheath portion  61 , the engagement of the hooking structure  77  and the middle portion  14  is maintained. The fracturable member  82  of the fracture mechanism  64  does not fracture. 
     (Action: Fracture State) 
     The slider  102  is pulled further back, a manipulation amount of power of the slider  102  reaches a value equal to or greater than a predetermined value, and the tensile force acting on the fracture mechanism  64  exceeds the fracture strength of the fracture mechanism  64 . At this time, the fracture mechanism  64  enters the fracture state in which a fracturable member inside the fracture mechanism  64  fractures. 
     After the fracturable member of the fracture mechanism  64  fractures, the fracture impact is transmitted to the user grasping the manipulation portion  100 . That is, the fracture mechanism  64  causes the user to recognize that the clip  10  is fixed in the closed state when the fracturable member of the fracture mechanism  64  fractures. Since the fracture mechanism  64  is provided in the manipulation portion  100 , the user can more reliably recognize this impact. 
     When the user feels the transmitted impact, the user can recognize that the clip  10  has entered the locking state and the ligation state of the target tissue T is maintained. Even when the user pulls the slider  102  further back and brings the slider  102  into contact with the proximal end of the slit  101   b  of the manipulation portion main body  101 , the user can recognize that the clip  10  has entered the locking state. 
     Since the clip  10  is in the locking state, the manipulation wire  62  is not moved toward the proximal end side. 
     A region R 5  shown in  FIG. 13  includes the fracture state and a state in which the slider  102  is pulled further back than the clip is in the fracture state. In the region R 5  shown in  FIG. 13 , the fracturable member of the fracture mechanism  64  fractures, the amount of power necessary to pull back the slider  102  temporarily decreases and then increases as the slider  102  is pulled back. In the region R 5 , the closed state of the clip  10  is maintained. Since the connection member  63  is disposed inside the sheath portion  61 , the engagement of the hooking structure  77  and the middle portion  14  is maintained. The fracturable member of the fracture mechanism  64  fractures. 
     (Action: Separation of Clip  10 ) 
     Thereafter, the clip  10  is separated from the treatment device body  40 . 
     The order in which the clip  10  is separated from the treatment device body  40  is specifically as follows. That is, when the slider  102  is pushed, the manipulation wire  62  is moved toward the distal end side with respect to the coil sheath  66 . As shown in  FIG. 22 , the distal end surface of the diameter expansion portion  72  comes into contact with the stepped portion  68  and the loop portion  73  protrudes up to the length L 2  which is the maximum protrusion amount with respect to the distal end member  67 . 
     When the connection member  63  protrudes on the distal end side with respect to the distal end member  67 , the clip main body  11  and the pressing tube  31  are integrally moved toward the distal end side. Since the connection member  63  is located out of the pressing tube  31 , the connection member  63  can be rotated with respect to the loop portion  73 . When the slider  102  is pushed and the manipulation wire  62  is moved toward the distal end side, the surface  76   b  of the connection member  63  comes into contact with the proximal end surface of the middle portion  14  of the clip  10  ligating the target tissue T. As shown in  FIG. 23 , the hooking structure  77  is guided to the surface  76   b  and is rotated in the direction D along with the bridge  76 , and thus the engagement of the hooking structure  77  and the middle portion  14  is released. Thus, the clip  10  ligating the target tissue T is maintained inside the body. 
     That is, the closed state of the clip  10  is maintained between the state indicated by the region R 5  and a state in which the slider  102  is pushed and the connection member  63  protrudes toward the distal end side with respect to the distal end member  67 , as shown in  FIG. 22 . The engagement of the hooking structure  77  and the middle portion  14  can be released. The fracturable member of the fracture mechanism  64  has been fractured. 
     (Action: Final Treatment of Technique) 
     The slider  102  is pulled back and the connection member  63  is accommodated inside the sheath portion  61 . 
     The endoscope treatment device  1  is extracted from the channel of the endoscope. The endoscope insertion portion of the endoscope is extracted from the body of the patient. Thereafter, any other necessary treatment is performed and a series of operations of the technique ends. 
     While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit and scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims 
     While various embodiments of the disclosed technology have been described above, it should be understood that they have been presented by way of example only, and not of limitation. Likewise, the various diagrams may depict an example schematic or other configuration for the disclosed technology, which is done to aid in understanding the features and functionality that can be included in the disclosed technology. The disclosed technology is not restricted to the illustrated example schematic or configurations, but the desired features can be implemented using a variety of alternative illustrations and configurations. Indeed, it will be apparent to one of skill in the art how alternative functional, logical or physical locations and configurations can be implemented to implement the desired features of the technology disclosed herein. 
     Although the disclosed technology is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead can be applied, alone or in various combinations, to one or more of the other embodiments of the disclosed technology, whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment. Thus, the breadth and scope of the technology disclosed herein should not be limited by any of the above-described exemplary embodiments. 
     Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as meaning “including, without limitation” or the like; the term “example” is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; the terms “a” or “an” should be read as meaning “at least one,” “one or more” or the like; and adjectives such as “conventional,” “traditional,” “normal,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future. Likewise, where this document refers to technologies that would be apparent or known to one of ordinary skill in the art, such technologies encompass those apparent or known to the skilled artisan now or at any time in the future. 
     The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent. 
     Additionally, the various embodiments set forth herein are described in terms of exemplary schematics, block diagrams, and other illustrations. As will become apparent to one of ordinary skill in the art after reading this document, the illustrated embodiments and their various alternatives can be implemented without confinement to the illustrated examples. For example, block diagrams and their accompanying description should not be construed as mandating a particular configuration.