Surgical instrument

Abstract

To provide a surgical instrument that can be decomposed but is not easily decomposed.SOLUTION: A surgical instrument includes: a shaft; a first member arranged in the shaft and whose movement in an axial direction of the shaft is restricted; a second member located independently from axial rotation of the shaft, positioned by a first surface of the first member, and having a first engagement part at a position extended to a second surface side opposite to the first surface; a third member located between the second member and the shaft and having a second engagement part that engages with the first engagement part; a fourth member located between the third member and the shaft and movable between a first position to which the second engagement part is fixed such that the engagement of the first engagement part and the second engagement part is not detached and a second position at which the fixation is released; and an energization member that has one end positioned by the second surface and energizes the fourth member such that the fourth member is located at the first position.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a surgical instrument having a floating structure.

Background Art

[0002] Among the instruments used in surgeries and the like, there are those having a so-called floating structure including a shaft and a rotating body provided on the shaft and rotatable around the shaft without coming off the shaft. In order to realize such a floating structure, a surgical instrument having such a floating structure needs to crimp or screw a fixture so that the rotating body does not come off the shaft.

[0003] For example, Patent Document 1 describes an instrument holder that allows the grip to elastically deform and expand when the holder is disassembled.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since a surgical instrument is used in surgery, postoperative cleaning is preferably performed in as fine a state as possible. Therefore, it is preferable that the instrument be decomposable. On the other hand, if it can be easily disassembled, there is a possibility that it may be disassembled during surgery and parts may fall into the body, so it is also required that it be difficult to disassemble during surgery.

Means for Solving the Problems

[0006] A surgical instrument according to one aspect of the present disclosure includes a shaft, a first member disposed on the shaft and restricted from axial movement of the shaft, a second member positioned independently of the axial rotation of the shaft, positioned by a first surface facing one end side of the shaft of the first member, and having a first engaging portion extending to a second surface side opposite to the first surface, a third member positioned between the second member and the shaft and having a second engaging portion that engages with the first engaging portion, a fourth member positioned between the third member and the shaft and movable between a first position for fixing the second engaging portion so that the engagement between the first engaging portion and the second engaging portion does not come off and a second position for releasing the fixing, and a biasing member having one end positioned by the second surface and biasing the fourth member so that the fourth member is positioned at the first position.

Advantages of the Invention

[0007] According to one aspect of the present disclosure, a surgical instrument that is not easily disassembled during use and can be easily disassembled when disassembly is desired can be realized.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0009] 〔Embodiment 1〕 Hereinafter, an embodiment of the present disclosure will be described in detail. First, as a surgical instrument according to this embodiment, the reduction tool 100 will be described by taking the rod adjustment instrument 1 as an example.

[0010] 〔Outline of Rod Adjustment Instrument 1〕 FIG. 1 is a diagram showing the overall outline of the rod adjustment instrument 1. The rod adjustment instrument 1 is an instrument for adjusting the position of the spine. As shown in FIG. 1, the rod adjustment instrument 1 includes a reduction tool 100, a fixed handle 110, a base 120, an extender 130, and a shaft 140.

[0011] The reduction tool 100 adjusts the position of the rod 170. Although details will be described later, the reduction tool 100 is arranged coaxially with the shaft 140 and can rotate around the shaft 140 independently of the rotation of the shaft 140. That is, it has a so-called floating structure that can rotate around the shaft 140 without coming off the shaft 140.

[0012] The fixed handle 110 is connected to the first end of the shaft 140, and by rotating the fixed handle 110 around the axis of the shaft 140, the shaft 140 is rotated. The second end of the shaft 140 opposite to the first end has a shape that engages with the hole in the head of the set screw 160. Thereby, by rotating the fixed handle 110, the set screw 160 can be rotated to fix the rod 170 to the pedicle screw 150.

[0013] The base 120 is screwed together with the reduction tool 100. When the reduction tool 100 rotates about the axis of the shaft 140, the outer 1312 of the extender 130 is moved axially while the position of the inner 1311 of the extender 130 is fixed. In this specification, the axial direction refers to the direction of the axis of the shaft 140. The axial direction can also be referred to as the longitudinal direction of the shaft 140.

[0014] The tip of the outer 1312 of the extender 130 is fitted with the pedicle screw 150. Therefore, by moving the outer 1312 axially with the inner 1311 of the extender 130 fixed, the position of the rod 170 in the pedicle screw 150 can be adjusted.

[0015] The shaft 140 is rod-shaped and has a constricted portion 141 where the area of the cross-section perpendicular to the axis is smaller than other locations.

[0016] The operator can operate the reduction tool 100 of the rod adjustment instrument 1 to adjust the position of the rod 170 in the pedicle screw 150. Furthermore, the operator can operate the fixing handle 110 of the rod adjustment instrument 1 to fix the rod 170 using the set screw 160.

[0017] 〔Details of the Reduction Tool 100〕 Next, with reference to FIGS. 2 to 7, the details of the reduction tool 100 will be described. FIG. 2 is a view showing the reduction tool 100 portion extracted from the rod adjustment instrument 1 shown in FIG. 1. FIG. 3 is a view showing the reduction tool 100 in a disassembled state.

[0018] As shown in FIGS. 2 and 3, the reduction tool 100 is arranged coaxially with the shaft 140 and includes a reduction handle 101 as the second member, a cap 102 as the third member, a retainer 103 as the fourth member, a spring 104 as the biasing member, a disk 105 as the fifth member, and a fixture 106 as the first member. That is, the reduction handle 101, the cap 102, the retainer 103, the spring 104, the disk 105, and the fixture 106 are arranged coaxially with the shaft 140.

[0019] As shown in FIG. 3, the cap 102, the retainer 103, the spring 104, the disk 105, the fixture 106, and the reduction handle 101 are inserted into the shaft 140 in this order.

[0020] The reduction handle 101 has a hollow shape, and the fixture 106, the disk 105, the spring 104, the retainer 103, and the cap 102 are fitted into the hollow portion in this order.

[0021] Referring to FIGS. 4 and 5, each component of the reduction tool 100 will be described. FIG. 4 is a view showing the reduction handle 101, the cap 102, and the retainer 103.

[0022] 〔Cap 102〕 401 in Fig. 4 shows the state of the cap 102 viewed axially. Also, 402 in Fig. 4 shows the state of the cap 102 viewed in a direction perpendicular to the axis. As shown in 401 and 402 of Fig. 4, the cap 102 is composed of a disk 1025 with a hole 1027 in the center and a side wall 1026 extending axially from the circumference of the disk 1025. A slit 1022 is located in the outer circumferential direction on the side wall 1026, and a leaf spring 1023 is formed. A protrusion protruding radially outward is formed as a second engaging portion 1021 on the portion of the leaf spring 1023 extending axially. The position of the second engaging portion 1021 is not limited to this, and it may be formed on the leaf spring 1023. That is, the second engaging portion 1021 may be formed at a location other than the portion of the leaf spring 1023 extending axially. Also, there may be a plurality of protrusions of the second engaging portion 1021. In this case, the plurality of second engaging portions 1021 may be located rotationally symmetrically with respect to the axis center of the shaft 140. Since the side wall 1026 is the surface where the cap 102 contacts the reduction handle 101, it can be called the third surface. Therefore, it can be said that the second engaging portion 1021 is located on the third surface.

[0023] A plurality of holes 1024 are located between the hole 1027 and the circumference on the disk 1025. The hole 1024 can be a hole into which the instrument is inserted when the cap 102 is pulled out from the reduction handle 101.

[0024] 〔Retainer 103〕 403 in Fig. 4 shows the state of the retainer 103 viewed axially. Also, 404 in Fig. 4 shows the state of the retainer 103 viewed in a direction perpendicular to the axis. As shown in 403 and 404 of Fig. 4, the retainer 103 is a disk 1035 with a hole 1037 in the center, and is composed of a disk 1035 with a two-step plate surface and a side wall 1036 extending axially from the circumference of the disk 1035. The side surface of the side wall 1036 has a two-step shape in which the second end side of the shaft 140 protrudes radially outward. The portion of the side wall 1036 protruding radially outward at the second end side is called a protruding portion 1031.

[0025] 〔Reduction handle 101〕 405 in Fig. 4 shows the reduction handle 101 viewed axially. Also, 406 in Fig. 4 shows the reduction handle 101 viewed in a direction perpendicular to the axis. As shown in 405 and 406 of Fig. 4, the reduction handle 101 has a hollow portion 1015 with an open surface on the first end side. The reduction handle 101 includes a first portion 101A where a recess 1013 is located on the outer surface, a second portion 101B connecting the first portion 101A and a third portion 101C described later, and a third portion 101C that is cylindrical with male threads cut on the side surface. On the inner surface of the hollow portion 1015 of the first portion 101A, a concave first engaging portion 1011 is located. Also, a bottom surface 1016 is located on the second end side of the hollow portion 1015. The bottom surface 1016 may be located at the boundary between the first portion 101A and the second portion 101B.

[0026] The reduction handle 101 may have a plurality of recesses 1013. Also, a hole 1014 is located in the recess 1013. When the reduction tool 100 is assembled, the hole 1014 is located at a position corresponding to the second engaging portion 1021, that is, the hole 1014 and the second engaging portion 1021 are located at the same position in the axial direction. By positioning the hole 1014 at a position corresponding to the second engaging portion 1021, the second engaging portion 1021 can be pushed toward the shaft 140 side through the hole 1014 using an auxiliary tool 72 described later.

[0027] 〔Disk 105〕 501 in Fig. 5 shows the disk 105 viewed axially. Also, 502 in Fig. 5 shows the disk 105 viewed in a direction perpendicular to the axis. As shown in 501 and 502 of Fig. 5, the disk 105 has a disk shape with a hole 1051 in the center. The disk 105 is not limited to a disk shape. For example, the shape of the disk 105 viewed in a direction perpendicular to the axis may be a polygonal shape or an elliptical shape. The disk 105 may have a hole 1051 in a portion other than the center.

[0028] 〔Fixture 106〕 503 in Fig. 5 shows the fixture 106 as viewed axially. Also, 504 in Fig. 5 shows the fixture 106 as viewed in a direction perpendicular to the axis. The shape of the fixture 106 as viewed in a direction perpendicular to the axis is circular. The shape of the fixture 106 as viewed in a direction perpendicular to the axis is not limited to a circular shape, and may be, for example, a polygonal shape or an elliptical shape. As shown in 503 and 504 of Fig. 5, the fixture 106 includes a disk 1065 with holes 1061 and 1062, and a side wall 1066 extending axially from the circumference of the disk 1065. The diameter of the disk 1065 of the fixture 106 is longer than the diameter of the cross-section of the shaft 140. The surface on the second end side of the disk 1065 is called the first surface, and the second surface on the first end side is called the second surface.

[0029] The hole 1061 is located at the center of the disk 1065, and the hole 1062 is located at a position offset from the center of the disk 1065. The holes 1061 and 1062 may be located at positions offset from the center of the disk 1065. Also, a part of the hole 1061 and the hole 1062 overlap, and the diameter da of the hole 1061 is smaller than the diameter db of the hole 1062. The diameter db of the hole 1062 is larger than the diameter of the axis of the shaft 140, and the diameter da of the hole 1061 is smaller than the diameter of the axis of the shaft 140.

[0030] The diameter da of the hole 1061 is larger than the diameter of the cross-section of the constricted portion 141 of the shaft 140 and smaller than the diameter of the cross-section of the shaft 140 other than the constricted portion 141. The diameter db of the hole 1062 is larger than the diameter of the cross-section of the shaft 140 other than the constricted portion 141.

[0031] When passing the fixture 106 through the shaft 140, it is done using the hole 1062. Then, at the position of the constricted portion 141, the shaft 140 is moved so that it is at the position of the hole 1061. Thereby, the fixture 106 can be passed through the shaft 140, and axial movement can be restricted at the position of the constricted portion 141.

[0032] 〔Structure of the reduction tool 100〕 Next, with reference to Fig. 6, the structure of the reduction tool 100 will be described.

[0033] 601 in Fig. 6 shows a state where only the reduction tool 100 is taken out from the rod adjustment tool 1. 602 and 603 in Fig. 6 are diagrams schematically showing a state where, in the state of 601, the reduction handle 101, the cap 102, and the retainer 103 are cut axially.

[0034] 602 in Fig. 6 shows a state where the retainer 103 is positioned at a first position where the engagement between the first engaging portion 1011 and the second engaging portion 1021 is not disengaged. 603 in Fig. 6 shows a state where the retainer 103 is positioned at a second position where the engagement between the first engaging portion 1011 and the second engaging portion 1021 can be disengaged.

[0035] As shown in 602 of Fig. 6, the reduction tool 100 has a structure in which the reduction handle 101, the fixture 106, the disk 105, the spring 104, the retainer 103, and the cap 102 are arranged from the second end side in the axial direction of the shaft 140, and the shaft 140 passes through them.

[0036] The fixture 106 is arranged on the bottom surface 1016 of the hollow portion 1015 of the reduction handle 101. The disk 105 is arranged on the disk 1065 of the fixture 106. In other words, the reduction handle 101 is positioned independently of the axial rotation of the shaft 140 and is positioned by the first surface of the fixture 106. Also, the first engaging portion 1011 is positioned on the circumferential surface side of the shaft 140 at a position extending to the second surface side opposite to the first surface of the fixture 106. One end of the spring 104 is arranged on the surface of the first end side of the disk 105, and the other end of the spring 104 is in contact with the inner surface of the retainer 103. That is, the disk 105 receives one end of the spring 104 on the surface of the first end side. Since the position of the fixture 106 with respect to the shaft 140 is fixed, the disk 105 arranged on the disk 1065 of the fixture 106 also does not move with respect to the shaft 140. Therefore, the retainer 103 is biased toward the first end side of the shaft 140 by the spring 104.

[0037] The cap 102 is arranged to cover the retainer 103. In other words, the retainer 103 is arranged within the space formed by the disk 1025 and the side wall 1026 of the cap 102. The surface on the first end side of the two-stage disk 1035 of the retainer 103 fits into the hole 1027 of the cap 102. In other words, the surface on the first end side of the disk 1035 of the retainer 103 is visible from the first end side.

[0038] The cap 102 is arranged within the hollow portion 1015 of the reduction handle 101. The second engaging portion 1021 of the cap 102 is engaged with the first engaging portion 1011 of the reduction handle 101. In other words, the cap 102 is positioned between the reduction handle 101 and the shaft 140. And the cap 102 has a second engaging portion 1021 that engages with the first engaging portion 1011.

[0039] When the disk 1035 of the retainer 103 is pressed against the disk 1025 of the cap 102 by the biasing force of the spring 104, the protrusion 1031 of the retainer 103 is in contact with the surface on the shaft 140 side of the second engaging portion 1021 of the cap 102 and is in a position to hold down the second engaging portion 1021 from the shaft 140 side. Therefore, when the retainer 103 is in this position, the second engaging portion 1021 cannot be pushed toward the shaft 140 side. Thus, it can be said that the engagement between the second engaging portion 1021 and the first engaging portion 1011 cannot be disengaged and the engagement between the second engaging portion 1021 and the first engaging portion 1011 is fixed.

[0040] On the other hand, when the retainer 103 is pushed in the direction of the second end of the shaft 140 against the biasing force of the spring 104, as shown in 603 of FIG. 6, the protrusion 1031 of the retainer 103 deviates in the direction of the second end from the position where it holds down the second engaging portion 1021. And a space is formed between the side wall 1036 of the retainer 103 and the second engaging portion 1021. As a result, the second engaging portion 1021 can be pushed in the direction of the shaft 140. By pushing the second engaging portion 1021 in the direction of the shaft 140, the engagement between the second engaging portion 1021 and the first engaging portion 1011 is disengaged. Therefore, by moving the retainer 103 to the position shown in 603 of FIG. 6, the engagement between the second engaging portion 1021 and the first engaging portion 1011 can be disengaged.

[0041] In this way, the retainer 103 is located between the cap 102 and the shaft 140, and is movable between a first position for fixing the second engaging portion 1021 so that the engagement between the first engaging portion 1011 and the second engaging portion 1021 is not disengaged, and a second position where the fixing is released. Further, one end of the spring 104 is positioned by the disk 105 located on the second surface of the fixture 106, and biases the retainer 103 so that the retainer 103 is located at the first position.

[0042] 〔Method for disassembling the reduction tool 100〕 Next, with reference to FIG. 7, a method for disassembling the reduction tool 100 will be described. FIG. 7 is a diagram for explaining the method for disassembling the reduction tool 100.

[0043] 701 in FIG. 7 shows a state in the reduction tool 100 where the retainer 103 is in the first position, that is, a state where the engagement between the first engaging portion 1011 and the second engaging portion 1021 is fixed. In this state, the reduction tool 100 cannot be disassembled. Therefore, even if the rod adjustment tool 1 is used in this state, the rod adjustment tool 1 will not be disassembled during use.

[0044] When disassembling the reduction tool 100 from this state, for example, using a tool 71 as shown in 702 of FIG. 7, the retainer 103 is pressed in the second end direction. The tool 71 is a cylindrical tool that can press only the surface on the first end side of the two-stage disk 1035 of the retainer 103.

[0045] When the retainer 103 is pressed in the second end direction, as shown in 703 of FIG. 7, the protrusion 1031 of the retainer 103 moves in the second end direction from the position where it presses the second engaging portion 1021 of the cap 102 from the shaft 140 side.

[0046] Next, for example, the tool 72 is pushed into the hole 1014 of the reduction handle 101 in the direction of the shaft 140. The tool 72 is a rod-shaped tool having a diameter that can be inserted into the hole 1014. By pushing the tool 72 into the hole 1014, the second engaging portion 1021 of the cap 102 can be pushed in the direction of the shaft 140. When the second engaging portion 1021 is pushed in the direction of the shaft 140, the engagement between the second engaging portion 1021 and the first engaging portion 1011 is disengaged. Therefore, if the cap 102 is moved in the first end direction in this state, as shown in 704 of FIG. 7, the cap 102 can be removed from the reduction handle 101.

[0047] If the cap 102 is removed from the reduction handle 101, as shown in 706 of FIG. 7, the retainer 103 can be removed from the reduction handle 101 in the first end direction. Thereafter, the spring 104 and the disk 105 are moved in the first end direction and removed from the reduction handle 101. The reduction handle 101 can be removed by moving it in the second direction of the shaft 140. Finally, the reduction tool 100 can be disassembled by removing the fixture 106 from the shaft 140.

[0048] The above-described disassembly method is an example, and it is also possible to disassemble the reduction tool 100 using various methods without using the auxiliary tools 71 and 72. Further, it is also possible to disassemble the reduction tool 100 using a tool having the functions of both the auxiliary tool 71 and the auxiliary tool 72.

[0049] 〔Embodiment 2〕 Other embodiments of the present disclosure will be described below. For convenience of explanation, members having the same functions as the members described in the above embodiments are denoted by the same reference numerals, and the description thereof will not be repeated.

[0050] In the present embodiment, the acetabular reamer 2 having the floating structure 200 as a surgical instrument will be described as an example.

[0051] The acetabular reamer 2 is an instrument used when reaming the acetabulum in hip joint replacement surgery or the like. Fig. 8 shows an overall overview of the acetabular reamer 2. As shown in Fig. 8, the acetabular reamer 2 includes a reamer portion 210 and a shaft 220. And the acetabular reamer 2 has a floating structure 200. Details of the floating structure 200 will be described with reference to Fig. 9.

[0052] 901 in Fig. 9 shows the acetabular reamer 2, and 902 in Fig. 9 shows the structure of the floating structure 200 of the X portion of 901.

[0053] As shown in 902 of Fig. 9, the floating structure 200 is composed of a handle 201, a cap 202, a retainer 203, a spring 204, a disk 205, and a fixture 206, and the shaft 220 penetrates through these.

[0054] The handle 201, the cap 202, the retainer 203, the spring 204, the disk 205, and the fixture 206 respectively correspond to the reduction handle 101, the cap 102, the retainer 103, the spring 104, the disk 105, and the fixture 106 of Embodiment 1. Therefore, the floating structure 200 has a function similar to that of the reduction tool 100 of Embodiment 1. Thereby, it is possible to realize the acetabular reamer 2 having a floating structure and being decomposable.

[0055] 〔Summary〕 The surgical instrument according to Aspect 1 of the present disclosure includes a shaft, a first member disposed on the shaft and restricted from moving in the axial direction of the shaft, a second member positioned independently of the axial rotation of the shaft and positioned by a first surface facing one end side of the shaft of the first member, and having a first engaging portion extending to a second surface side opposite to the first surface, a third member positioned between the second member and the shaft and having a second engaging portion that engages with the first engaging portion, a fourth member positioned between the third member and the shaft and movable between a first position for fixing the second engaging portion so that the engagement between the first engaging portion and the second engaging portion does not come off, and a second position for releasing the fixing, and a biasing member that biases the fourth member so that one end is positioned by the second surface and the fourth member is positioned at the first position.

[0056] According to the above configuration, a floating structure in which the second member operates independently of the axial rotation of the shaft can be realized. This is because the fourth member prevents the second member from falling off from one direction of the shaft and the fourth member existing on the opposite side of the shaft across the first member from falling off from the opposite direction of the shaft.

[0057] And according to the above configuration, the fourth member is arranged at the first position by the biasing force of the biasing member, and the engagement between the first engaging portion and the second engaging portion is fixed, so that the second member, the third member, and the fourth member are not disassembled. Therefore, during use, that is, when the fourth member is at the first position, a structure that cannot be easily disassembled can be realized.

[0058] Further, if a force is applied against the biasing force, the position of the fourth member can be moved to a second position different from the first position. Thereby, the engagement between the second member and the third member can be disengaged, and the second member, the third member, and the fourth member can be disassembled.

[0059] From the above, during use, a surgical instrument that is not easily disassembled and can be easily disassembled when disassembly is desired can be realized.

[0060] In the surgical instrument according to Embodiment 2 of the present disclosure, in the above Embodiment 1, the first member is a disk having a substantially circular surface and is arranged coaxially with the shaft. Thereby, the rotation of the shaft and the rotation of the surgical instrument can be made coaxial.

[0061] In the surgical instrument according to Embodiment 3 of the present disclosure, in the above Embodiment 1 or 2, when the fourth member is in the first position, it is in contact with the surface of the third member on the shaft side. Thereby, it is possible to reduce the third member from being pushed into the shaft side.

[0062] In the surgical instrument according to Embodiment 4 of the present disclosure, in any of the above Embodiments 1 to 3, when the fourth member is in the first position, it is in contact with the surface of the second engaging portion on the shaft side. Thereby, the engagement between the first engaging portion and the second engaging portion can be fixed.

[0063] In the surgical instrument according to Embodiment 5 of the present disclosure, in any of the above Embodiments 1 to 4, when the fourth member is in the second position, it does not contact the surface of the second engaging portion on the shaft side. Thereby, it becomes possible to disengage the engagement between the first engaging portion and the second engaging portion.

[0064] In the surgical instrument according to Embodiment 6 of the present disclosure, in any of the above Embodiments 1 to 5, the first engaging portion is located on the circumferential surface side of the shaft in the second member. Thereby, the first engaging portion and the second engaging portion can be engaged.

[0065] The surgical instrument according to aspect 7 of the present disclosure is, in any one of aspects 1 to 6, wherein the second engaging portion is a protrusion located on a leaf spring extending along the side surface of the shaft on a third surface of the third member that contacts the second member. Thereby, the engagement between the second member and the third member can be strengthened.

[0066] The surgical instrument according to aspect 8 of the present disclosure is, in aspect 6, wherein there are a plurality of the protrusions, and each of the plurality of protrusions is rotationally symmetrically positioned with respect to the axial center of the shaft. Thereby, the engagement between the second member and the third member can be made stable.

[0067] The surgical instrument according to aspect 9 of the present disclosure is, in aspect 7 or 8, wherein the leaf spring is formed by a slit extending in the outer peripheral direction of the shaft. According to the above configuration, the strength of the leaf spring can be made appropriate.

[0068] The surgical instrument according to aspect 10 of the present disclosure is, in any one of aspects 1 to 9, wherein the shaft has a constricted portion whose cross section perpendicular to the longitudinal direction is smaller than other portions, and the first member is positioned at the constricted portion. Thereby, the first member can be prevented from coming off the shaft.

[0069] The surgical instrument according to aspect 11 of the present disclosure is, in aspect 10, wherein the first member has a hole that is larger than a cross section perpendicular to the longitudinal direction of the constricted portion and smaller than a cross section perpendicular to the longitudinal direction of the shaft other than the constricted portion. Thereby, the first member can be prevented from coming off the shaft.

[0070] The surgical instrument according to aspect 12 of the present disclosure is, in any one of aspects 1 to 11, and has a fifth member that is positioned between the biasing member and the second surface of the first member and receives the biasing member. Thereby, the biasing force of the biasing member can be accurately transmitted to the fourth member.

[0071] The surgical instrument according to aspect 13 of the present disclosure, in any of aspects 1 to 12, has a concave portion on the outer surface of the second member. Thereby, by placing a finger or the like on the concave portion, the user can easily operate the second member.

[0072] The surgical instrument according to aspect 14 of the present disclosure, in aspect 13, has a plurality of the concave portions. Thereby, the user can easily operate the second member.

[0073] As described above, the invention according to the present disclosure has been described based on the drawings and examples. However, the invention according to the present disclosure is not limited to the above-described embodiments. That is, the invention according to the present disclosure can be variously modified within the scope shown in the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that those skilled in the art can easily make various deformations or modifications based on the present disclosure. Also, note that these deformations or modifications are included in the scope of the present disclosure.

Explanation of Reference Numerals

[0074] 1 Rod adjustment instrument 100 Reduction tool 101 Reduction handle (second member) 102 Cap (third member) 103 Retainer (fourth member) 104 Spring (biasing member) 105 Disk (first member) 106 Fixture (fifth member) 110 Fixed handle 130 Extender 120 Base 140 Shaft 150 Pedicle screw 160 Set screw 170 Rod 2 Acetabular reamer 200 Floating structure 201 Handle 202 Cap 203 Retainer 204 Spring 205 Disk 206 Fixture 220 Shaft

Claims

1. A shaft, a first member disposed on the shaft and restricting axial movement of the shaft, a second member positioned independently of the axial rotation of the shaft, positioned by a first surface facing one end side of the shaft of the first member, and having a first engaging portion at a position extending to the second surface side opposite to the first surface, a third member positioned between the second member and the shaft and having a second engaging portion that engages with the first engaging portion, a fourth member positioned between the third member and the shaft and movable between a first position for fixing the second engaging portion so that the engagement between the first engaging portion and the second engaging portion does not come off and a second position for releasing the fixing, and a biasing member that biases the fourth member such that one end is positioned by the second surface and the fourth member is positioned at the first position. A surgical instrument comprising.

2. The surgical instrument according to claim 1, wherein the first member is a disk having a substantially circular surface and is arranged coaxially with the shaft.

3. The surgical instrument according to claim 1, wherein the fourth member is in contact with the surface of the third member on the shaft side when the fourth member is in the first position.

4. The surgical instrument according to claim 1, wherein the fourth member is in contact with the surface of the second engaging portion on the shaft side when the fourth member is in the first position.

5. The surgical instrument according to claim 1, wherein the fourth member does not contact the surface of the second engaging portion on the shaft side when the fourth member is in the second position.

6. The surgical instrument according to claim 1, wherein the first engaging portion is located on the circumferential surface side of the shaft in the second member.

7. The surgical instrument according to claim 1, wherein the second engaging portion is a protrusion located on a leaf spring extending along the side surface of the shaft on a third surface of the third member that contacts the second member.

8. The surgical instrument according to claim 7, wherein there are a plurality of the protrusions, and each of the plurality of protrusions is rotationally symmetric with respect to the axial center of the shaft.

9. The surgical instrument according to claim 7, wherein the leaf spring is formed by a slit extending in the outer circumferential direction of the shaft.

10. The shaft has a constricted portion where the cross section perpendicular to the longitudinal direction is smaller than other portions, and the first member is located at the constricted portion. The surgical instrument according to claim 1.

11. The surgical instrument according to claim 10, wherein the first member has a hole that is larger than a cross-section perpendicular to the longitudinal direction of the constricted portion and smaller than a cross-section perpendicular to the longitudinal direction of the shaft other than the constricted portion.

12. The surgical instrument according to claim 1, further comprising a fifth member that is located between the biasing member and the second surface of the first member and receives the biasing member.

13. The surgical instrument according to claim 1, wherein an outer surface of the second member has a recess.

14. The surgical instrument according to claim 13, wherein there are a plurality of the recesses.

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