JP2015205134A - Levator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a levator enabling minimally invasive operation while having flexural rigidity and flexural strength for reduction, and enabling operation in an accurate physical relationship through X-ray transmission.SOLUTION: A levator 1 includes a spatula-like lever part 1b, and a grip part 1a continuing to one end side of the lever part. The lever part 1a has an X-ray transmissive area constituted from carbon fiber-reinforced plastic, and an X-ray non-transmissive area constituted from a metallic material in a plane view outer edge in at least part on the other end side. The tip part of the lever part 1b has a board thickness of 3.2 mm or less, and a board width of 12 mm or less. The levator 1 has deflection of 18 mm or less in the case of adding 10 kgf loading, and flexure hardness of 23 kgf or more.

Description

  The present invention relates to levatorium, and more particularly to levatorium used for reduction.

In plastic surgery, various instruments such as retractors and elebatium are used. For example, elevatrium is used for lifting hard tissues such as bones in plastic surgery and reducing metastasized bone fragments in fracture surgery (Patent Document 1).
Here, in plastic surgery, doctors and nurses may check the X-ray monitor, and may proceed with the procedure while confirming the positional relationship between the levatorium, the retractor, and the like and the target site. In such a case, there is a problem that a metal elevatrium that has been used conventionally cannot confirm bones and the like located on the back side.

  In order to deal with such a problem, it is conceivable to adopt the configuration of the retractor proposed in Patent Document 2. In Patent Document 2, a portion (tip portion) of the retractor that is in close contact with a living tissue is formed of an X-ray transmitting member (resin material or the like), and an X-ray non-transmitting member (metal material or the like) is provided on the outer edge portion thereof. A configuration is disclosed.

Japanese Patent No. 4494188 JP 2009-254752 A

  However, even if elevatrium is formed by adopting the configuration proposed in Patent Document 2, there is a problem in use for reduction. Specifically, the configuration proposed in Patent Document 2 relates to a retractor for maintaining a surgical wound in an expanded state, and simply applying this to an elevatrium results in bending rigidity and mechanical properties. Problems may arise from the perspective of strength.

In addition, when the size of each part is increased in order to ensure bending rigidity and bending strength (mechanical strength), it is necessary to form a large incision part for inserting Elevatorium, reducing the burden on the patient (low (Invasion) may cause a problem. The problem is particularly great when the patient is an infant or a child.
The present invention has been made to solve such problems, and is capable of minimally invasive treatment while having bending rigidity and bending strength for reduction, and is based on fluoroscopy. An object of the present invention is to provide an elebatium capable of performing treatment in an accurate positional relationship.

The elevatrium according to the present invention is an elevatrium that can be used for reduction, and has the following characteristics.
The elevatrium according to the present invention includes a spatula-shaped lever portion and a grip portion that continues to one end of the lever portion. The lever portion has an X-ray transmission region made of a carbon fiber reinforced plastic, and an X-ray non-transmission region made of a metal material at an outer edge in a plan view on at least a part of the other end side. The tip of the lever portion has a plate thickness of 3.2 mm or less and a plate width of 12 mm or less.

  Further, the elevatrium according to the present invention has a deflection of 18 mm or less and a bending strength of 23 kgf or more when a load of 10 kgf is applied.

  In the levatorium according to the present invention, the lever portion has an X-ray transmission region and an X-ray non-transmission region. And the X-ray non-transmission area | region is provided in the planar view outer edge of the other end side (tip side) of a lever part. Therefore, in the levatorium according to the present invention, it is possible to proceed with the treatment while confirming the positional relationship between the levatorium, the retractor and the like and the target portion by confirming the X-ray monitor.

Moreover, in the levatorium which concerns on this invention, the plate | board thickness of the front-end | tip part in a lever part is prescribed | regulated to 3.2 mm or less, and the board width is prescribed to 12 mm or less. Thereby, it is not necessary to form a large incision part for insertion, and it becomes possible to reduce a burden for patients such as infants and children.
Further, in the levatorium according to the present invention, the deflection when a load of 10 kgf is applied is 18 mm or less, and the bending strength is 23 kgf or more. For this reason, from the viewpoint of bending rigidity and bending strength, it is equivalent to a conventional stainless steel levatorium, and does not cause a problem during reduction.

As described above, the elevatrium according to the present invention can be subjected to minimally invasive treatment while having bending rigidity and bending strength for reduction, and can be performed in an accurate positional relationship by X-ray fluoroscopy. To do.
The elevatrium according to the present invention may employ the following variation configuration as an example.

In addition to the above configuration, the levatorium according to the present invention is knurled on one main surface of the lever portion. When such a configuration is adopted, it is possible to suppress slipping between the bones during reduction.
In addition to the above-described configuration, the grip portion of the levatorium according to the present invention is integrally formed of carbon fiber reinforced plastic that constitutes the X-ray transmission region of the lever portion. When such a configuration is employed, the joint between the lever portion and the grip can be eliminated. Therefore, even if it is used for a long time, there is no problem such as rattling.
Moreover, by forming integrally, compared with the case where it has a joint, the problem of propagation of various bacteria in the said part, adhesion of refuse, etc. does not arise.

  In addition to the above-described configuration, the levatorium according to the present invention has a plate thickness of 3.0 mm at the tip portion and 7.0 mm at the base portion on the grip portion side, from the tip portion toward the root portion. Increasing gradually. And the plate | board width in a lever part is 12 mm in a front-end | tip part, is 17.6 mm in a base part, and is increasing gradually toward a root part from a front-end | tip part. By setting it as such thickness and width | variety, bending rigidity and bending strength are securable, suppressing the enlargement of a size.

Further, by configuring the lever portion so that the thickness and width of the lever portion gradually change, the deflection when the doctor or nurse applies force during reduction gradually changes. Thus, from the viewpoint of the relationship between the applied load and the deflection, it is possible to ensure excellent operability during reduction.
In addition to the above configuration, the levatorium according to the present invention has two bent portions formed between the tip portion and the root portion in the lever portion, and each bent portion draws an arc in a side view. Is formed. By adopting such a configuration, it is excellent particularly when manipulating the bone fragment of the femoral trochanter.

It is a model perspective view which shows the external appearance shape of Elevatorium 1 which concerns on embodiment of this invention. It is a model side view which shows each part detailed shape and each part size of Elevatorium 1. It is a model top view which shows each part detailed shape and each part size of Elevatorium 1. (A) is a schematic cross section which shows a partial structure of Elevatorium 1, (b) is the cross-sectional view. 2 is a schematic perspective view showing an example of use of the elevator trim 1. FIG. (A) is an X-ray image of Elevatorium 1 according to the embodiment, and (b) is an X-ray image of Elevatorium according to the comparative example. It is a model side view which shows the method of the rigidity and intensity | strength test of the levatorium 1 which concerns on an Example. (A) is a graph which shows the test result regarding the bending rigidity of Elevatorium, (b) is a graph which shows the test result regarding the fracture strength of Elevatorium. It is a model side view which shows the structure of the levatorium 2 which concerns on the modification 1. It is a model top view which shows the structure of the elevatrium 3 which concerns on the modification 2. FIG. 10 is a schematic cross-sectional view showing a partial configuration of elevatrium 4 according to Modification 3.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
In addition, the embodiment according to the following description is used as an example for easily explaining the structural features of the present invention and the effects obtained from the structural features. Except for the essential features, the present invention is not limited to the following forms.
[Embodiment]
1. Schematic shape The schematic shape of the elevatrium 1 according to the embodiment of the present invention will be described with reference to FIG. In addition, the levatorium 1 which concerns on this Embodiment assumes the levatorium used by the reduction with respect to a femur fracture as an example.

As shown in FIG. 1, the levatorium 1 according to the embodiment of the present invention is integrally formed with a grip portion 1a and a lever portion 1b that extends from one end side (lower side in the Z-axis direction) and has a spatula shape. It becomes. Elevatorium 1 according to the present embodiment is formed using carbon fiber reinforced plastic (CFRP) as a main material.
In addition, the front-end | tip part 1c of the lever part 1b is formed in the substantially circular arc shape.
2. Each part detailed shape Next, each part detailed shape and each part size of Elevatorium 1 are demonstrated using FIG. 2 and FIG.

As shown in FIG. 2, the levatorium 1 is a bar-like portion that extends vertically in the Z-axis direction in a side view. On the other hand, the lever portion 1b is a portion having a shape having two bent portions 1b2 and 1b4.
Grip 1a, the length of the Z-axis direction is the L _1. The length L ₁ is a dimension that takes into account the size of a human hand, and is set to, for example, 120 mm to 140 mm (for example, 138.8 mm). The cross-sectional size of the grip portion 1a is also in consideration of the size of the human hand.

When the lever part 1b is seen in detail, it has the 1st part 1b1 extended in a Z-axis direction following the grip part 1a, and the 2nd part 1b3 extended in the direction which cross | intersects with respect to the 1st part 1b1. What is provided between the first portion 1b1 and the second portion 1b3 is a first bent portion 1b2 formed in an arc in curvature radius R _1, the second portion 1b3 and the tip portion 1c What it is provided in between, a second bent portion 1b4 formed in an arc with a radius of curvature R _2.

Here, a virtual extension line of one main surface of the first portion 1b1, a point P ₁ the intersection of the imaginary extension of the main surface of the same side of the second portion 1b3. At this time, the distance L ₂ in the Z-axis direction of the end portion of the grip portion 1a from (the upper end of the Z-axis direction) to the point P ₁ is, for example, (as an example, 211.5mm) 200mm~220mm is set to .
Y-axis direction of the distance L ₃ from the tip portion 1c of the lever portion 1b to the point P ₁ is, for example (as one example, 135.8mm) 125mm~145mm set to.

Further, the Y-axis direction right end point of the main surface of the second portion 1b3 and P _2. In this case, the distance L ₄ in the Y-axis direction from the tip portion 1c of the lever portion 1b to the point P ₂ is (as an example, 101.5mm) 90mm~110mm is set to.
The thickness of each portion of the lever portion 1b is a plate thickness t ₁ of the first portion 1b1 is root portion 7.0 mm, is 3.0mm thickness t ₃ of the tip portion 1c. The thickness of the lever portion 1b from the tip portion 1c is set to gradually increase toward the first portion 1b1, the thickness t ₂ of the second portion 1b3 is 4.2 mm.

As shown in FIG. 3, the plate width W ₁ of the base portion of the first portion 1b1 is 17.0 mm to 18.0 mm (as an example, 17.6 mm) with respect to the plate width of each portion of the lever portion 1b. plate width W ₂ parts 1c is (as an example, 12.0mm) 11.0mm~13.0mm is.
Returning to FIG. 2, the angle θ ₁ formed by the first portion 1b1 and the second portion 1b3 is set to 90 ° to 110 ° (for example, 100 °), and the radius of curvature R of the first bent portion 1b2 is set. ₁ is set to 40.0 mm to 45.0 mm (for example, 42.5 mm).

On the other hand, the bending of the tip portion 1c with respect to the second portion 1b3 is such that the angle θ ₂ between the tip portion 1c and the vicinity thereof and a virtual ship parallel to the Z axis is set to 50 ° to 60 ° (for example, 55 °). Has been. Then, the radius of curvature R ₂ of the second bent portion 1b4 is, 37.5Mm～42.5Mm (e.g., 39.7 mm) is set to.
As shown in the enlarged portion of FIG. 2, a knurling process for preventing slipping is performed on the main surface on the lower side in the Z-axis direction in a portion from the middle portion of the second portion 1b3 of the lever portion 1b to the tip portion 1c. (Knurled portion 1d). The depth of the knurl is, for example, 0.5 mm.
3. The structure of the lever part 1b The structure of the lever part 1b is demonstrated using FIG. FIG. 4 is a schematic plan view of a part of the distal end side of the lever portion 1b.

As shown in FIGS. 4 (a) and 4 (b), the lever section 1 b of the elevator trim 1 is composed of a carbon main body portion 10 and a metal portion 11. Among these, the carbon main body 10 is made of carbon fiber reinforced plastic (CFRP), which is an X-ray transmitting material, as described above. On the other hand, the metal part 11 is comprised from the stainless steel wire which is a X-ray non-transparent material.
The metal part 11 is embedded along the outer edge 1bs of the lever part 1b and the outer edge 1cs of the tip part 1c. For this reason, the metal part 11 has a form in which the straight parts 11a and 11b and the arcuate part 11c are continuously formed.

The metal portion 11 may be formed over the entire length of the lever portion 1b, but in the present embodiment, the metal portion 11 is formed within the length L _{5 in} the Z-axis direction from the distal end portion 1c. Yes. The length L ₅ is not particularly limited as long as it is equal to or longer than the length necessary for reduction while viewing the X-ray image. For example, it can be set as the structure which provides the metal part 11 to the boundary part of the 2nd part 1b3 and the 1st bending part 1b2.

As shown in FIG. 4 (b), in Elevatorium 1, in consideration of the ease of hygiene management, the metal part 11 is configured to be covered with the carbon body part 10 so as not to be exposed to the outside. .
4). Usage Example A usage example of Elevatorium 1 will be described with reference to FIGS. 5 and 6.

As shown in FIG. 5, in reduction using Elevatorium 1, while confirming the X-ray image, the state in which the surgical wound is expanded using a retractor or the like is maintained, and the vicinity of the trochanter portion of the femur 500 in this state The lever part 1b is inserted into. And the main surface of the side in which the knurled part 1d from the front-end | tip part 1c to the 2nd part 1b3 in the lever part 1b was formed is made to contact a bone.
Here, as shown in FIG. 6A, in the levatorium 1 according to the present embodiment, in the lever portion 1b, only the region provided with the metal portion 11 at the outer edge is an X-ray non-transmissive region, and the rest The region becomes an X-ray transmission region.

On the other hand, as shown in FIG. 6B, as a comparative example, in the Elevatorium in which the entire lever portion 91b is formed of stainless steel (SUS), the entire lever portion 91b becomes an X-ray non-transparent region, and is subject to reduction. It is difficult to confirm the bones and tissues.
A doctor or the like presses or lifts a bone fragment while checking an X-ray image as shown in FIG. At this time, the levatorium 1 according to the present embodiment is formed in the size as described above, so that the bending required for reduction while the lever portion 1b is constituted by the carbon main body portion 10 and the metal portion 11. Rigidity and bending strength are ensured.
5. Confirmation of Bending Rigidity and Bending Strength The test results of bending rigidity and bending strength performed on Elevatorium 1 will be described with reference to FIGS.
(1) Measuring method First, the measuring method of bending rigidity and bending strength is demonstrated using FIG.

As shown in FIG. 7, the elevatrium 1 is placed so that the end of the grip portion 1 a is in contact with the test table 550. And the grip part 1a is inserted | pinched with the chuck | zipper parts 551,552, and the Elevatorium 1 is fixed to the test stand 550. FIG.
Next, with the levatorium 1 fixed to the test bench 550, the loading head 553 is brought into contact with the surface on the knurled portion 1d side (see FIG. 2) of the second bent portion 1b4 of the lever portion 1b. Then, the loading head 553 is pushed in the direction of arrow B. In the measurement, the relationship between the push-in amount (deflection) and the load is sequentially performed.
(2) Test sample (i) Example 1
The basic configuration of the levatorium according to the first embodiment is the same as that of the levatorium 1 described above. The thickness t ₁ of the first portion 1b1 is the same at 7.0 mm, and the difference is that the thickness t ₃ of the tip 1c is 4.8 mm. And about the plate | board thickness between the 1st part 1b1 and the front-end | tip part 1c, it is increasing in proportion to the difference in the plate | board thickness of the front-end | tip part 1c.

In addition, about the dimension of another part, the numerical value shown as an example above is employ | adopted.
For the carbon main body 10, a material having an elastic modulus of 240 GPa was used.
(Ii) Example 2
The elevatrium according to the second embodiment is also the same in that the basic configuration is the same as that of the elevatrium 1, and the thickness t ₁ of the first portion 1b1 is 7.0 mm. In Example 2, the thickness of the tip 1c is 4.5 mm, and the thickness between the first portion 1b1 and the tip 1c is increased in proportion to the difference in the thickness of the tip 1c. doing.

In addition, about the dimension of another part, the numerical value shown as an example above is employ | adopted.
For the carbon main body 10, a material having an elastic modulus of 240 GPa was used.
(Iii) Example 3
The elevatrium according to Example 3 has the same configuration and size as the elevatrium 1 described above. Here, the numerical values shown as an example in the above are adopted for various dimensions.

For the carbon main body 10, a material having an elastic modulus of 240 GPa was used.
(Iv) Comparative Example In the elevatrium according to the comparative example, the lever portion conventionally used is made of stainless steel (SUS). For the dimensions of each part, the numerical values shown as an example for the above-mentioned Elevatorium 1 are adopted.
(3) Flexural Rigidity As shown in FIG. 8A, the deflection-load characteristics of each levatorium according to Examples 1 to 3 and the comparative example were measured. As shown to Fig.8 (a), in the levatorium which concerns on Example 1, 2, it was the bending rigidity higher than the levatorium which concerns on a comparative example.

On the other hand, with the levatorium according to Example 3, it was possible to obtain a deflection-load characteristic equivalent to that of the levatorium according to the comparative example.
From the above results, the levatorium according to Example 3, that is, the elevatrium 1 is most suitable for the SUS elevatrium conventionally used from the viewpoint of bending rigidity. Even when doctors replace the SUS levatorium used in the past with the levatorium of Example 3 and perform reduction, the feeling of operation and the like does not change greatly, and the most uncomfortable feeling It is thought that treatment is possible without memorizing.

However, when more bending rigidity is required, the levatorium of Examples 1 and 2 can be adopted.
(4) Bending strength As shown in FIG. 8 (b), the Elevatorium according to the comparative example caused plastic deformation when a load of 36.5 kgf was applied.

The evabatium according to Example 1 was broken at a load of 46.8 kgf, and the levatorium according to Example 2 was broken at a load of 38.6 kgf.
On the other hand, the elevatrium according to Example 3 was broken at a load of 23.8 kgf. The bending strength of Elevatorium according to Example 3 is lower than the strength at which Elevatorium according to the comparative example causes plastic deformation, but is considered to have sufficient strength when considering the load applied during reduction.
(5) Summary From the above results, the elevatrium according to Example 3 in which the thickness of the tip portion 1c is 3.0 mm has the same characteristics in terms of operability as the conventional SUS evabatium, and is reduced. It can be said that it is the most excellent from the viewpoint of minimally invasive to patients undergoing treatment.

However, when greater bending rigidity, bending strength, and the like are required, it is also an option to adopt the levatorium of Examples 1 and 2.
[Modification 1]
The structure of the levatorium 2 which concerns on the modification 1 is demonstrated using FIG. In addition, description is abbreviate | omitted about the part which is not different from the Elevatorium 1 which concerns on the said embodiment.

As shown in FIG. 9, in the Elevatorium 2 according to this modification, the grip portion 21 and the lever portion 22 are configured as separate members. Specifically, the grip portion 21 is made of resin or the like, and the lever portion 22 is embedded in carbon fiber reinforced plastic (CFRP), which is an X-ray transmitting material, and a part of the lever portion 22 in the same manner as the Elevatorium 1 described above. And a metal part.
As shown in FIG. 9, in Elevatorium 2, part 22 a of lever part 22 is fitted into a hole formed in grip part 21, and the remaining part 22 b extends from grip part 21.

In addition, although detailed illustration is abbreviate | omitted, about the shape of the part 22b in the lever part 22, it is common with the said Elevatorium 1. FIG. One main surface (main surface on the lower side in the Z-axis direction) of the partial region 22d from the tip 22c is knurled.
The same effect as that of Elevatorium 1 according to the above-described embodiment can be obtained with Elevatorium 2 according to Modification Example 1. In addition, it is possible to make the grip portion 21 easy to be gripped by a doctor or the like, and a high degree of freedom in design can be ensured.

[Modification 2]
The structure of the levatorium 3 which concerns on the modification 2 is demonstrated using FIG. In the following, description of the parts that are not different from Elevatorium 1 according to the above embodiment will be omitted.
As shown in FIG. 10, the Elevatorium 3 according to the present modification also has a configuration in which a grip part 31 and a lever part 32, which are separate members, are joined together as in the first modification. The grip portion 31 is formed using a material such as resin.

  In the Elevatorium 3 according to this modification, the metal main body portion 321 that is the main portion of the lever portion 32 is formed using stainless steel (see the enlarged cross-sectional portion). In the metal main body 321, a hole 321 a is formed in a part 32 b on the right side in the Z-axis direction from the tip end 32 c. A carbon portion 320 made of carbon fiber reinforced plastic (CFRP), which is an X-ray transmitting material, is formed in the hole 321a.

  In the levatorium 3 according to this modification, the main part of the lever part 32 is made of stainless steel, and the carbon part that constitutes the X-ray transmission region in the part 32b on the distal end side that is a place to be confirmed in the X-ray image image 320 is provided. Therefore, also in the levatorium 3 which concerns on this modification, reduction | restoration is possible, confirming an X-ray image image, making bending rigidity and bending strength equivalent to the conventional stainless steel levatorium.

[Modification 3]
The structure of the levatorium 5 which concerns on the modification 3 is demonstrated using FIG. In the following, description of the parts that are not different from Elevatorium 1 according to the above embodiment will be omitted.
As shown in FIG. 11, the structural feature of the elevatrium 5 according to the present modification is the shape of the metal part 51 embedded in the carbon main body 50 in a plan view. As shown in FIG. 11, the metal part 51 has linear parts 51 a and 51 b and an arcuate part 51 c provided along the outer edges of the lever part 5 b and the tip part 5 c. It is the same.

In addition to the above, the metal portion 51 of the levatorium 5 according to the present modification is provided with measure portions 51d _{1 to} 51d ₇ that connect the straight portions 51a and 51b and are parallel to each other. These measure units 51d _{1 to} 51d ₇ have a function as a measure for confirming the positional relationship and size of the bone or tissue to be transmitted to a doctor who performs reduction while viewing the X-ray image. It is.

Note that the intervals between the major portions 51d _{1 to} 51d ₇ may be equal intervals or may be different. In the case of equal intervals, for example, the intervals can be 5 mm or 10 mm.
In the elevatrium 5 according to this modification, a doctor or the like who performs reduction using this can recognize the size, distance, and the like by looking at the X-ray image.

[Other matters]
In the above, carbon fiber reinforced plastic (CFRP) is adopted as an example of the X-ray transmitting material, but the present invention is not limited to this. For example, in addition to CFRP, an epoxy-based resin material or the like can be used.
Similarly, although a wire made of stainless steel or the like is used as an example of the X-ray non-transparent material, the present invention is not limited to this. For example, a metal material such as copper (Cu) or titanium (Ti), or an alloy thereof can be used.

Moreover, in the said embodiment, the modification 1, 3, etc., it was decided that the metal parts 11 and 51 and the metal main parts 10 and 50 were completely embedded and the metal parts 11 and 51 were not exposed on the surface. Again, the present invention is not limited. A part may be exposed on the surface of the lever portion.
Moreover, in the said embodiment etc., although the lever part 1b employ | adopted the form which has the two bending parts 1b2 and 1b4, this invention is not limited to this. Appropriate changes can be made in consideration of the shape of the bone to be reduced and the surrounding tissue.

  INDUSTRIAL APPLICABILITY The present invention is useful for realizing an elevatrium that is minimally invasive and excellent in operability when performing reduction while confirming the position by X-ray fluoroscopy.

1, 2, 3, 5. Erebatium 10,50. Carbon main body 11,51. Metal part 1a, 21, 31. Grip part 1b, 22, 32. Lever part 320. Carbon part 321. Metal body 500. Femur 550. Test bench 551,552. Chuck part 553. Loading head

Claims (5)

An elevatrium having a spatula-shaped lever portion and a grip portion continuing to one end side of the lever portion,
The lever portion has an X-ray transmission region made of carbon fiber reinforced plastic, and an X-ray non-transmission region made of a metal material at an outer edge in plan view at least at a part of the other end side,
The tip of the lever portion has a plate thickness of 3.2 mm or less and a plate width of 12 mm or less.
The deflection when a load of 10 kgf is applied is 18 mm or less,
Elevatorium characterized by a bending strength of 23 kgf or more. The knurling process is given to one main surface in the said lever part. The levatorium of Claim 1 characterized by the above-mentioned. The said grip part is integrally formed with the said carbon fiber reinforced plastic which comprises the said X-ray transmissive area | region of the said lever part. The levatorium of Claim 1 or Claim 2 characterized by the above-mentioned. The plate thickness of the lever part is 3.0 mm at the tip part, 7.0 mm at the base part on the grip part side, and gradually increases from the tip part toward the root part,
The plate width of the lever portion is 12 mm at the tip portion and 17.6 mm at the root portion, and gradually increases from the tip portion toward the root portion. The elevatrium according to claim 3. The lever portion has two bent portions formed between the tip portion and the root portion,
Each levatorium according to claim 4, wherein each bent portion is formed so as to draw an arc in a side view.