Surgical instruments

Abstract

The purpose of the present invention is to relieve the burden on a surgeon in positional adjustment for determining the target position for a surgical procedure without increasing the surgical instrument size. In the present invention, a surgical instrument is provided with a body part, a moving part, and a fixed part. The body part has a first male thread on the outer peripheral surface thereof, and a second female thread on the inner peripheral surface thereof. The moving part has a position indicator indicating position, and a first female thread with which the first male thread engages. The fixed part has a second male thread that engages with the second female thread. The first male thread and a second male thread are in an inverse thread relation.

Description

Technical Field

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[0001] The present disclosure relates to surgical instruments, particularly to surgical instruments used in artificial knee joint replacement surgery.

Background Art

[0002] In artificial knee joint replacement surgery, a surgical instrument shown in Patent Document 1 is known. Patent Document 1 discloses an orthopedic instrument system including a surgical burr, a housing, a locking knob, a mounting frame, and a cutting block. The orthopedic instrument system is capable of advancing a part of the housing to engage with the surgical burr when the locking knob is rotated to a second position.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] A surgical instrument according to one aspect of the present disclosure includes a main body portion having a first male screw on an outer peripheral surface of a cylinder and a second female screw on an inner peripheral surface thereof, a position indicating portion indicating a target position, and a moving portion having a first female screw into which the first male screw is screwed, and a fixing portion having a second male screw screwed into the second female screw. The rotation of the moving portion in the rotation direction of the first male screw is restricted, and the first male screw and the second male screw are in a reverse screw relationship.

Brief Description of the Drawings

[0005] [Figure 1] It is a perspective view showing a usage example of the surgical instrument according to Embodiment 1 of the present disclosure. [Figure 2] It is a perspective view of the surgical instrument shown in FIG. 1. [Figure 3] It is a front view of the surgical instrument shown in FIG. 1. [Figure 4]Figure 1 is a side view of the surgical instrument shown. [Figure 5] Figure 1 is an exploded perspective view of the surgical instruments shown. [Figure 6] This is a perspective view showing a portion of the screw structure shown in Figure 1, with a cutout. [Figure 7] Figure 6 is a cross-sectional view of the screw structure. [Figure 8] Figure 6 is a schematic diagram of the screw structure. [Figure 9] This figure shows the initial state of the positional adjustment of the surgical instruments shown in Figure 1. [Figure 10] This figure shows the state of the surgical instruments after their positions have been adjusted, as shown in Figure 1. [Modes for carrying out the invention]

[0006] [Embodiment 1] Embodiment 1 of this disclosure will be described below with reference to the drawings. In the following description, an example will be given in which the surgical instrument is used as a guide device to indicate the cutting position at the proximal end of the tibia in total knee arthroplasty. However, this disclosure is not limited to this, and the surgical instrument can also be used as a guide device to indicate the cutting position at the distal end of the femur in total knee arthroplasty. Furthermore, the surgical instrument can also be applied to the position adjustment of surgical instruments in other surgical procedures, such as total hip arthroplasty and total ankle arthroplasty.

[0007] Furthermore, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the embodiments in order to make the explanation clearer; therefore, the width, thickness, shape, etc. of each part are not limited to this disclosure.

[0008] <Overview> First, to facilitate understanding of surgical instrument 1, we will briefly explain the outline of the total knee replacement surgery procedure and an example of the use of surgical instrument 1, referring to Figure 1.

[0009] Total knee replacement surgery is a procedure that replaces a patient's knee joint with an artificial knee joint. The artificial knee joint comprises a tibial implant (not shown) placed at the proximal end B1 of the patient's tibia B, and a femoral implant (not shown) that engages with the tibial implant and is placed at the distal end of the femur (not shown).

[0010] The user, such as an orthopedic surgeon, uses bone resection instruments 7, such as a bone saw or reamer driver, to resect the proximal end B1 of the patient's tibia B and a portion of the distal end of the femur, respectively, to create mounting surfaces for implants. The user then attaches a tibial implant to the mounting surface of the tibia B and a femoral implant to the mounting surface of the femur, thereby replacing the patient's knee joint with an artificial knee joint.

[0011] Surgical instrument 1 is used, for example, in the above process when the proximal end B1 of the tibia B is resected to form a mounting surface.

[0012] Figure 1 is a perspective view showing an example of the use of surgical instrument 1. As shown in Figure 1, first, a surgical reamer 9 or rod, which is a separate instrument from surgical instrument 1, is inserted into the bone marrow of the tibia B. As will be described in more detail later, surgical instrument 1 is fixedly attached to this surgical reamer 9. Surgical instrument 1 comprises a reamer attachment part 2, a guide member 3, a screw 4, a movable part 5, and a fixing part 6.

[0013] The surgical instrument 1 includes a rod-shaped guide member 3 that extends approximately perpendicular to the surgical reamer 9 when attached to the surgical reamer 9. Here, the insertion direction of the surgical reamer 9 is defined as the Y1 direction (downward), and the direction opposite to the Y1 direction is defined as the Y2 direction (upward), as shown by arrows Y1 and Y2 in Figure 1. Furthermore, the direction parallel to the direction in which the guide member 3 extends and approximately perpendicular to Y1 and Y2, approaching the surgical reamer 9, is defined as the X1 direction (leftward), and the direction moving away from the surgical reamer 9 is defined as the X2 direction (rightward), as shown by arrows X1 and X2 in Figure 1. In addition, the vertical direction may be referred to as the Y direction, and the horizontal direction as the X direction.

[0014] The surgical instrument 1 described in this embodiment is for the left foot. For the right foot, the shape is such that the relationship between the first part 52A (described later) and the second part 52B (described later) with respect to the moving part 5 is reversed.

[0015] The fixing part 6 includes an insertion hole 62 (see FIG. 2) through which the guide member 3 is inserted. The fixing part 6 is attached so as to be movable in the X direction along the guide member 3 by inserting the guide member 3 into the insertion hole 62.

[0016] The moving part 5 includes a position indicating part 52 that indicates the cutting position of the tibia B. The moving part 5 is attached to the fixing part 6 via a screw 4. Although details will be described later, the user can move the moving part 5 in the Y direction by turning the screw 4 and finely adjust the height position of the position indicating part 52. Here, the height position refers to the position in the Y direction, that is, the vertical direction. By adjusting the height position, the user can move the position indicating part 52 to an appropriate position with respect to the target site of bone resection of the tibia B.

[0017] Thereby, a user such as an orthopedic surgeon can insert the bone resection instrument 7 into one of the slits 521 (described later) of the position indicating part 52 and perform bone resection of the tibia B at a desired position.

[0018] <Configuration of the surgical instrument> Next, the configuration of the surgical instrument 1 will be described in detail with reference to FIGS. 2 to 5. FIG. 2 is a perspective view of the surgical instrument 1, FIG. 3 is a front view, FIG. 4 is a side view, and FIG. 5 is an example of an exploded perspective view.

[0019] As described above, the surgical instrument 1 includes a reamer attachment part 2, a guide member 3, a screw 4, a moving part 5, and a fixing part 6.

[0020] As shown in FIGS. 2 to 5, the reamer attachment part 2 includes an insertion hole 21 and a screw 22.

[0021] The insertion hole 21 is formed along the entire length of the reamer mounting portion 2 in the Y direction. The user inserts the surgical reamer 9, which is inserted into the bone marrow of the tibia B, into the insertion hole 21 through the opening below the insertion hole 21 and secures it with the screw 22. This allows the user to attach the surgical instrument 1 to the surgical reamer 9.

[0022] Furthermore, the user may roughly adjust the height of the surgical instrument 1 so that the position indicator 52 is in an appropriate position relative to the target site of bone resection of the tibia B.

[0023] The guide member 3 protrudes from the lower part of the reamer mounting portion 2 and is formed in a rod shape that extends in the X direction, that is, substantially perpendicular to the surgical reamer 9. As described above, the guide member 3 is inserted through the insertion hole 62 of the fixing portion 6 and is prevented from coming out by the ball plunger 31. As a result, the fixing portion 6 is mounted so as to be movable in the X direction along the guide member 3.

[0024] The screw 4 is used to fine-tune the height of the movable part 5, and comprises a main body 41 and an operating part 42 for operating the screw 4. The operating part 42 is provided at one end of the main body 41, and the diameter of the operating part 42 is larger than the diameter of the main body 41. In this embodiment, the operating part 42 is provided at the Y2 side end of the main body 41. By turning the operating part 42, the user can rotate the main body 41, and by turning the operating part 42, the user can fine-tune the height of the movable part 5.

[0025] The main body portion 41 is the shaft portion of the screw 4 extending in the Y direction and is formed in a cylindrical shape. A first male screw 411 (see Figure 5) is formed on the outer circumferential surface of the main body portion 41, and a second female screw 412 (see Figure 5) is formed on the inner circumferential surface. Furthermore, as shown in Figure 6, which will be described later, the main body portion 41 has a cylindrical space that extends from the Y1 end of the main body portion 41 to the Y2 side into the interior of the main body portion 41. The second female screw 412 is formed from the Y1 end of the inner circumferential surface of the cylindrical space to a predetermined position. In addition, the cylindrical space of the main body portion 41 extends into the interior of the operating portion 42, and the tip on the Y2 side is tapered.

[0026] The first male screw 411 and the second female screw 412 are arranged to be coaxial with each other in the Y direction, along with the first female screw 511 of the movable part 5 (see Figure 5) and the second male screw 61 of the fixed part 6 (see Figure 5), which will be described later.

[0027] Furthermore, since the second male screw 61 is formed on the fixing part 6, it is configured not to rotate or move up and down.

[0028] Furthermore, the screw 4 is joined to the movable part 5 by the first male screw 411 screwing into the first female screw 511, and to the fixed part 6 by the second female screw 412 screwing into the second male screw 61.

[0029] As will be explained in more detail later, the first male screw 411 and the second male screw 61 are configured to have opposite threads to each other. For example, if the first male screw 411 is a left-hand thread, the second male screw 61 will be a right-hand thread. Conversely, if the first male screw 411 is a right-hand thread, the second male screw 61 will be a left-hand thread.

[0030] Here, a right-hand screw is a screw with a thread that tightens when turned clockwise and loosens when turned counterclockwise. In other words, a right-hand screw is a screw in which turning the male screw clockwise causes it to screw into the female screw, and turning it counterclockwise causes it to unscrew from the female screw.

[0031] On the other hand, a left-hand thread is the opposite of a right-hand thread; it has a thread groove that tightens when turned counterclockwise and loosens when turned clockwise. In other words, a left-hand thread is a screw that, when turned counterclockwise, advances in the direction of screwing into a female thread, and when turned clockwise, advances in the direction of unscrewing from a female thread.

[0032] By making the first male screw 411 and the second male screw 61 reverse threads, when the user turns the operating part 42 in the direction that loosens the first male screw 411, the moving part 5 moves downward so as to move away from the main body 41 of the screw 4. Also, when the user turns it in this way, the second female screw 412 also rotates, and the second male screw 61 of the fixing part 6 is screwed into the second female screw 412, causing the screw 4 to move downward so as to move closer to the fixing part 6.

[0033] At this time, since the movable part 5 is attached to the fixed part 6, even if the operating part 42 is turned, it does not rotate together with the screw 4, but moves downward.

[0034] As a result, the movable part 5 can move a distance equal to the sum of the downward movement distance of the movable part 5 itself (M1) and the downward movement distance of the screw 4 (M2) (M1 + M2). In other words, by using a screw structure that combines two screws with opposite threads, the first male screw 411 and the second male screw 61, the amount of movement relative to the rotation angle can be increased compared to when movement is achieved with a single screw.

[0035] This allows the user to move the movable part 5 significantly by rotating the screw 4 by only a small angle, thereby reducing the burden on the user associated with position adjustment.

[0036] Details on fine-tuning the height of the movable part 5 using screw 4 will be described later.

[0037] The movable part 5 includes a holding part 51 and a position indicating part 52 that indicates the position of bone resection of the tibia B.

[0038] The retaining portion 51 has a first female screw 511, a through hole 512, a housing space 513, a mark 514, and a stopper 515.

[0039] The first female thread 511 is formed, for example, on the inner circumferential surface of a through hole 512 formed in the upper part of the retaining portion 51. The first female thread 511 is screwed into the first male thread 411, which is inserted into the through hole 512 from above.

[0040] The housing space 513 is formed, for example, below the through hole 512, and houses the fixing part 6 with the guide member 3 inserted through it.

[0041] Furthermore, the movable part 5 is attached to the fixed part 6 via screws 4 while the fixed part 6 is housed in the storage space 513. Therefore, the user can adjust the distance in the X direction between the position indicator part 52 of the movable part 5 and the tibia B by moving the fixed part 6 along the guide member 3 in the X direction. Specifically, moving the fixed part 6 in the X1 direction brings the position indicator part 52 closer to the tibia B, and moving the fixed part 6 in the X2 direction moves the position indicator part 52 further away from the tibia B.

[0042] Mark 514 is, for example, a triangular mark displayed on one surface of the holding portion 51. Mark 514 is displayed, for example, on both sides of the scale portion 63 of the fixing portion 6 (described later), and is displayed to indicate the numerical value or scale of the scale portion 63. This allows the user to visually confirm the distance of the position indicator portion 52 from the reference plane P0 of the bone resection (described later).

[0043] Mark 514 may be, for example, a linear or rhombus-shaped mark, and is not limited to a triangle. Also, Mark 514 may be displayed on only one side of the scale section 63. Details of Mark 514 and the scale section 63 will be described later.

[0044] The stopper 515 restricts the upward movement range of the movable part 5. This prevents, for example, the position indicator 52 from colliding with the guide member 3 due to excessive upward movement of the movable part 5, thereby preventing damage to the surgical instrument 1. The stopper 515 may also restrict the movement range so that, for example, when the mark 514 indicates a predetermined value on the scale 63, the movable part 5 does not move any further upward, and the stopper 515 may be positioned in such a location.

[0045] The position indicator 52 indicates the cutting position at the proximal end B1 of the tibia B, and when the tibia B is osteoctomized, the osteoctomy instrument 7 is inserted and guides the osteoctomy instrument 7 to the cutting position of the tibia B.

[0046] The position indicator section 52 is detachably connected to the holding section 51. The position indicator section 52 has a first section 52A and a second section 52B, which are provided with a slit 521, a guide plate 522, a pin insertion hole 523, and a fixing pin 524, respectively.

[0047] The first part 52A is located on the left side (medial side, towards the center of the body) when facing the area of ​​tibia B to be resected, and the second part 52B is located on the right side (lateral side, towards the outside of the body). The first part 52A and the second part 52B are positioned at an angle to each other so as to cover the area of ​​tibia B to be resected.

[0048] As shown in Figure 4, the first part 52A and the second part 52B are not symmetrical, with the first part 52A being wider than the second part 52B. This is because, as mentioned above, the surgical instrument 1 is for the left foot. Due to the constraints on the direction in which the bone resection instrument can enter during the surgical procedure, the first part 52A and the second part 52B are asymmetrical in this way. This is because there is space on the medial side but not on the lateral side during surgery. Conversely, the right foot version is configured such that, when facing the bone resection site of the tibia B, the width of the part on the right side is greater than the width of the part on the left side.

[0049] Furthermore, the first part 52A may have the same height in the Y direction as the second part 52B.

[0050] The guide plate 522 is a plate-shaped member formed to be substantially parallel to the X direction. The position indicator unit 52 comprises a plurality of guide plates 522 arranged at intervals from each other.

[0051] Furthermore, the guide plates 522 may be spaced apart from each other to match the height of various implants placed in the artificial joint. This further reduces the burden on the user when adjusting their position.

[0052] The slit 521 is formed to penetrate in the X direction. The slit 521 divides the position indicator 52 into multiple guide plates 522, except for the boundary between the first portion 52A and the second portion 52B.

[0053] The slit 521 is formed so that its height in the Y direction is greater than that of the bone resection instrument 7, in order to allow insertion of the bone resection instrument 7.

[0054] Furthermore, the slit 521 indicates the cutting position of the tibia B. Specifically, the upper surface 522a of the guide plate 522, which is the boundary between the slit 521 and the guide plate 522, is the cutting position of the tibia B. By providing multiple slits 521, the position indicator unit 52 can indicate multiple cutting positions with a single alignment.

[0055] The pin insertion hole 523 is a through-hole for inserting a fixing pin 524 that secures the position indicator 52 to the tibia B. After the height adjustment of the position indicator 52 is complete, it is fixed to the tibia B by the fixing pin 524 inserted into the pin insertion hole 523.

[0056] After fixing the position indicator 52 to the tibia B, the surgical instruments 1 and surgical reamer 9 other than the position indicator 52 are removed from the tibia B. The user inserts the bone resection instrument 7 into the slit 521 of the position indicator 52, slides the inserted bone resection instrument 7 along the upper surface 522a of the guide plate 522 toward the tibia B, and performs bone resection at the desired position.

[0057] In the example described above, the position indicator unit 52 was shown to have multiple slits 521, but it is not limited to this, and the position indicator unit 52 may have only one slit 521. In this case, the position indicator unit 52 may have a pair of guide plates 522 flanking the slit 521, or it may have no slits 521 and only one guide plate 522. In this case, the user moves the bone resection instrument 7 along the upper surface 522a of the guide plate 522 to resection the tibia B.

[0058] The fixing part 6 includes a second male screw 61, an insertion hole 62, a scale part 63, and a base 64.

[0059] The second male screw 61 protrudes upward from the base 64 of the fixing part 6 and, as described above, engages with the second female screw 412 formed on the inner circumferential surface of the screw 4. Furthermore, the second male screw 61 is formed to have a reverse thread relationship with the first male screw 411.

[0060] As described above, the insertion hole 62 allows the guide member 3 to be inserted, and the fixing part 6 is attached to the guide member 3. Therefore, the fixing part 6 moves in the X direction along the guide member 3 together with the movable part 5, but does not move in the Y direction. Furthermore, the fixing part 6 is fixed to the surgical reamer 9 inserted into the tibia B via the guide member 3. As a result, the fixing part 6 is fixed to the tibia B, so the cutting position can be accurately indicated.

[0061] The scale section 63 is displayed on one surface of the fixed section 6 so that it can be seen by the user, and displays at least one of either the scale markings or a numerical value.

[0062] The scale section 63 is displayed on the surface of the movable section 5 that coincides with the side on which the mark 514 is displayed, while the fixed section 6 is housed in the storage space 513 of the movable section 5. This allows the user to see the scale section 63 and the mark 514 simultaneously, and thus visually confirm the scale or numerical value of the scale section 63 indicated by the mark 514.

[0063] Furthermore, mark 514 indicates the distance in the Y direction from the reference plane P0 (see Figure 9), which will be described later, when the scale of the reference plane P0 is set to 0. To explain in detail, the scale part 63 is displayed on the fixed part 6 and therefore does not move in the Y direction, but mark 514 on the movable part 5 moves along with the movement of the movable part 5. As a result, the numerical values ​​etc. indicated by mark 514 indicate the distance in the Y direction from the reference plane P0 of the movable part 5.

[0064] <Screw structure> (Amount of movement relative to the rotation angle) Next, the fine adjustment of the height of the position indicator part 52 using the screw 4 will be explained in detail with reference to Figures 6 to 8. Figure 6 is a perspective view showing a part of the screw structure, Figure 7 is a cross-sectional view of the screw structure, and Figure 8 is an example of a schematic diagram of the screw structure.

[0065] As shown in Figures 6 to 8, the fine adjustment mechanism for the height of the position indicator 52 is realized by a screw structure that combines two screws, a first male screw 411 and a second male screw 61, which have opposite thread relationships to each other.

[0066] As described above, the first male screw 411, the second female screw 412, the second male screw 61, and the first female screw 511 are configured to be coaxial with each other, with the first male screw 411 screwing into the first female screw 511 and the second male screw 61 screwing into the second female screw 412.

[0067] Furthermore, the first male screw 411 and the second male screw 61 are configured to have opposite threads to each other. Also, since the second male screw 61 is formed on the fixed part 6, it is configured not to rotate or move up and down.

[0068] The following describes an example in which the first male screw 411 is a left-hand thread and the second male screw 61 is a right-hand thread, and the position indicator 52 is moved downward.

[0069] When the user turns the operating part 42 clockwise from the side opposite to where the fixing part 6 is screwed in, that is, from above the screw 4, the main body part 41 rotates clockwise.

[0070] When the user rotates the main body 41 clockwise, the second male screw 61 causes the main body 41 to move toward the fixed part 6 (Y1), and the first male screw 411 causes the movable part 5 to move toward the fixed part 6 (Y1).

[0071] As a result, the movable part 5 moves by the sum of the amount moved by the first male screw 411 (M2) and the amount moved by the second male screw 61 (M1) (M1 + M2) from its position before operation. Therefore, the amount of movement can be increased for the same rotation angle compared to when it is moved by a single screw.

[0072] In this way, by combining two screws with opposite threads, the first male screw 411 and the second male screw 61, the amount of movement relative to the rotation angle can be increased compared to when movement is achieved with a single screw.

[0073] This allows the user to move the movable part 5 significantly by rotating the screw 4 by only a small angle, thereby reducing the burden on the user during position adjustments during surgery.

[0074] Furthermore, normally, when a user turns a screw clockwise, the male screw is screwed into the female screw. That is, the male screw moves in the direction of the female screw. In Embodiment 1, the first male screw 411 is a left-hand thread, so when a user turns the main body 41 clockwise, the movable part 5 moves away from the main body 41. That is, the movable part 5 moves in the opposite direction to the main body 41, so the movable part 5 can be moved to match the user's natural senses.

[0075] However, this is not the only option; the first male screw 411 may be a right-hand thread and the second male screw 61 may be a left-hand thread.

[0076] The second male screw 61 has a smaller diameter than the first male screw 411 because a second female screw 412 is formed on the inner surface of the first male screw 411 to engage with the second male screw 61. As a result, the amount of movement (lead) when it rotates is smaller than that of the first male screw 411. This allows the movable part 5 to be moved by using the first male screw 411 and the second male screw 61 in a balanced manner.

[0077] (Size of screw structure) If the same amount of movement as the combined movement of the first male screw 411 and the second male screw 61 is to be achieved with a single screw, the diameter and shaft length of that single screw must be increased. Increasing the diameter and shaft length of a screw also increases the size of the component containing the screw, which can obstruct the user's field of view. This can lead to problems in artificial knee joint replacement surgery, where precise procedures are required.

[0078] However, the screw structure according to Embodiment 1 allows for increased movement without increasing the size of the screw, and the surgical instrument 1 can be made more compact.

[0079] (Multi-start screw) Furthermore, in the screw structure according to Embodiment 1, at least one of the first male screw 411 and the second male screw 61 may be a multi-start screw, such as a double-start screw. This further increases the amount of movement with respect to the rotation angle. Also, if it is desired to finely adjust the amount of movement per rotation, only one of the screws may be a multi-start screw.

[0080] <Position adjustment> In the following section, an example of inserting the bone resection instrument 7 into slit 521A and performing bone resection at a position 10 mm below the reference plane P0 will be described with reference to Figures 9 and 10.

[0081] Figure 9 illustrates an example of the initial state of surgical instrument 1 after position adjustment, where the figure indicated by reference numeral 9A is a front view and the figure indicated by reference numeral 9B is a side view. Figure 10 illustrates an example of the state after position adjustment of surgical instrument 1, where the figure indicated by reference numeral 10A is a front view and the figure indicated by reference numeral 10B is a side view.

[0082] The user first determines the reference plane P0 for bone resection. The reference plane P0 for bone resection may be, for example, a plane containing a single point that serves as the reference for bone resection, but is not particularly limited.

[0083] As shown in Figure 9, first, the user turns screw 4 to adjust the scale indicated by mark 514 to 0. In this state, the user loosens screw 22 to adjust the height so that the position of the reference plane P0 matches the height of the upper surface 5221a of the guide plate 5221 adjacent to the slit 521A. Alternatively, the user may loosen screw 22 to adjust the height position so that the scale indicated by mark 514 reaches 0 when the height positions of the reference plane P0 and the upper surface 5221a of the guide plate 5221 adjacent to the slit 521A are aligned.

[0084] After adjusting the height position, the user secures the surgical instrument 1 by tightening the screw 22 again, thereby establishing a reference plane P0 where the scale is at zero. Subsequent height adjustments are performed using this reference plane P0 as the reference.

[0085] If, for example, the user wants to trim the end face of the tibia B at the reference plane P0, the user inserts the bone resection instrument 7 into the slit 521A and slides the bone resection instrument 7 along the upper surface 5221a of the guide plate 5221 to resection the tibia B.

[0086] Next, the user adjusts the height of the movable part 5 by turning the screw 4 so that the scale indicated by mark 514 reaches 10, as shown in Figure 10. The position where the scale indicates 10 is the position where the height of position P1, which is 10 mm below the position of the reference plane P0, coincides with the height of the upper surface 5221a of the guide plate 5221.

[0087] At the position where the scale indicates 10, the user inserts the bone resection instrument 7 into the slit 521A and slides the bone resection instrument 7 along the upper surface 5221a of the guide plate 5221 to resection the tibia B.

[0088] [Embodiment 2] Other embodiments of this disclosure are described below. For convenience of explanation, components having the same function as those described in the above embodiments are denoted by the same reference numerals, and their descriptions are not repeated.

[0089] The movable part 5 of Embodiment 1 is composed of a holding part 51 and a position indicating part 52, but the movable part 5 of Embodiment 2 differs from Embodiment 1 in that it is composed of a holding part 51 and a treatment part 53 (not shown) which includes a bone resection instrument 7.

[0090] The height of the treatment section 53 can be finely adjusted by rotating the screw 4. This allows for direct adjustment of the position of the bone resection instrument 7, thereby improving the efficiency of the surgery.

[0091] The inventions described in this disclosure have been explained above based on the drawings and embodiments. However, the inventions described in this disclosure are not limited to the embodiments described above. That is, the inventions described in this disclosure can be modified in various ways within the scope shown in this disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the inventions described in this disclosure. In other words, it should be noted that it is easy for those skilled in the art to make various modifications or alterations based on this disclosure. Furthermore, it should be noted that these modifications or alterations are included in the scope of this disclosure. [Explanation of Symbols]

[0092] 1 surgical instruments 5. Mobile section 6 Fixed part 41 Main body 52 Position indicator 53 Treatment Department 61 Second male screw 411 First male screw 412 Second female thread 511 First female thread 521 Slit

Claims

1. A main body having a first male thread on the outer circumference of the cylinder and a second female thread on the inner circumference, A position indicator section that shows the target position, and a movable section having a first female screw into which the first male screw is screwed, It comprises a fixing part having a second male thread that screws into the second female thread, The aforementioned movable part is restricted from rotating in the rotational direction of the first male screw. The first male screw and the second male screw are in a reverse thread relationship. A surgical instrument in which the movable part is movably arranged on the outer surface of the fixed part.

2. The surgical instrument according to claim 1, wherein the position indicating part is a guide that indicates the bone cutting position as the target position.

3. The surgical instrument according to claim 2, wherein the guide includes at least one slit.

4. The surgical instrument according to claim 2, wherein the fixing portion can be fixed to a separate instrument fixed to the bone.

5. The surgical instrument according to claim 1, wherein when the main body is turned clockwise when viewed from the side opposite to the side to which the fixing part is screwed, the screw threads of the first male screw are provided such that the movable part moves away from the main body.

6. The surgical instrument according to claim 1, wherein at least one of the first male screw and the second male screw is a multi-start screw.

7. A main body having a first male thread on the outer circumference of the cylinder and a second female thread on the inner circumference, A position indicator section that shows the target position, and a movable section having a first female screw into which the first male screw is screwed, It comprises a fixing part having a second male thread that screws into the second female thread, The aforementioned movable part is restricted from rotating in the rotational direction of the first male screw. The first male screw and the second male screw are in a reverse thread relationship. The position indicator is a guide that indicates the bone cutting position as the target position. The surgical instrument is such that the cutting position of the bone is at the proximal end of the tibia.

8. A main body having a first male thread on the outer circumference of the cylinder and a second female thread on the inner circumference, A position indicator section that shows the target position, and a movable section having a first female screw into which the first male screw is screwed, It comprises a fixing part having a second male thread that screws into the second female thread, The aforementioned movable part is restricted from rotating in the rotational direction of the first male screw. The first male screw and the second male screw are in a reverse thread relationship. A surgical instrument in which the amount advanced when the second male screw is rotated once is less than the amount advanced when the first male screw is rotated once.

9. A main body having a first male thread on the outer circumference of the cylinder and a second female thread on the inner circumference, A position indicator section that shows the target position, and a movable section having a first female screw into which the first male screw is screwed, It comprises a fixing part having a second male thread that screws into the second female thread, The aforementioned movable part is restricted from rotating in the rotational direction of the first male screw. The first male screw and the second male screw are in a reverse thread relationship. An operating part is provided at one end of the main body, and the main body is rotatable, A surgical instrument in which the diameter of the operating section is larger than the diameter of the main body.

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