阅读说明：本技术 定圆心-球心万向调节旋转半径错距微创骶髂螺钉导向器 (Circle-center-sphere-center universal rotation radius-adjusting minimally invasive sacroiliac screw guider ) 是由 邓迎生 邓喆尹 于 2019-10-30 设计创作，主要内容包括：本发明公开了一种定圆心-球心万向调节旋转半径错距微创骶髂螺钉导向器,包括矩形主定位器、横向弧形调节器、空心定位杆和空心导向控制器。本发明将矩形主定位器与横向弧形调节器相结合,能够实现根据病人不同病情确定进钉点、调节骶髂螺钉置入方向并可一次性准确置入骶髂螺钉的功能,解决现有技术存在的问题。横向弧形调节器的使用使得医生可根据病人的解剖结构和不同病情自由调节插入横向弧滑道的横向弧形刻度杆上的刻度以匹配在横断面上骶髂螺钉与人体矢状面的夹角、并使骶髂螺钉钉道的延长线经过虚拟旋转圆心或虚拟旋转球心O点,以便准确确定骶髂螺钉的内倾角。(The invention discloses a minimally invasive sacroiliac screw guider capable of universally adjusting rotation radius and offset distance by centering a circle and a sphere, which comprises a rectangular main positioner, a transverse arc adjuster, a hollow positioning rod and a hollow guiding controller. The invention combines the rectangular main positioner with the transverse arc regulator, can realize the functions of determining the nail feeding point according to different disease conditions of patients, regulating the inserting direction of the sacroiliac screw and accurately inserting the sacroiliac screw at one time, and solves the problems in the prior art. The use of the transverse arc regulator enables a doctor to freely regulate the scales on the transverse arc scale rod inserted into the transverse arc slideway according to the anatomical structure and different disease conditions of a patient so as to match the included angle between the sacroiliac screw and the sagittal plane of a human body on the transverse section and enable the extension line of the sacroiliac screw nail track to pass through the virtual rotation circle center or the virtual rotation sphere center O point, so that the internal inclination angle of the sacroiliac screw can be accurately determined.)

1. A minimally invasive sacroiliac screw guider with fixed circle center and spherical center for universal adjustment of rotating radius offset is characterized in that: comprises a rectangular main positioner, a transverse arc regulator, a hollow positioning rod and a hollow guide controller;

the rectangular main positioner comprises a positioner body and a transverse arc-shaped sleeve arranged at the front end of the positioner body, the positioner body is provided with a sacrum positioning hole and an ilium fixing hole which are through up and down, and the sacrum positioning hole and the ilium fixing hole are both provided with locking members;

the transverse arc regulator comprises a transverse arc scale rod and a guider arranged at the left end of the transverse arc scale rod; the transverse arc-shaped scale rod penetrates through the transverse arc-shaped sleeve and can slide in the transverse arc-shaped sleeve;

the hollow positioning rod is arranged on the rectangular main positioner, a detachably connected threaded guide pin is arranged in the hollow positioning rod, and the hollow positioning rod can be movably inserted into the sacrum positioning hole and can be locked by a locking component on the sacrum positioning hole;

the hollow guide controller comprises a hollow sleeve, and the hollow sleeve is arranged on the guide.

2. The circle-center-sphere-center universally-adjustable rotation radius offset minimally invasive sacroiliac screw guide of claim 1, wherein: the top surface of the transverse arc-shaped sleeve is arranged horizontally or forwards and downwards obliquely relative to the top surface of the positioner body.

3. The circle-center-sphere-center universally-adjustable rotation radius offset minimally invasive sacroiliac screw guide of claim 1, wherein: penetrating horizontal arc slide about being equipped with in the horizontal arc sleeve, horizontal arc slide is unanimous with the radian of horizontal arc scale rod, horizontal arc scale rod is equipped with the scale on the surface.

4. The circle-center-sphere-center universally-adjustable rotation radius offset minimally invasive sacroiliac screw guide of claim 1, wherein: the upper portion and the lower portion of the hollow positioning rod are cylindrical, the diameter of the lower portion of the hollow positioning rod is smaller than that of the upper portion of the hollow positioning rod, and scales are arranged on the outer surface of the cylindrical upper portion of the hollow positioning rod.

5. The circle-center-sphere-center universally-adjustable rotation radius offset minimally invasive sacroiliac screw guide of claim 1, wherein: the guider is a guide block or a longitudinal arc-shaped scale rod; the hollow sleeve penetrates through the guide block and then is movably arranged on the guider or is arranged on the longitudinal arc-shaped scale rod through the sliding block, and scales are arranged on the surface of the longitudinal arc-shaped scale rod.

6. The circle-center-sphere-center universally-adjustable rotation radius offset minimally invasive sacroiliac screw guide of claim 5, wherein: the longitudinal arc-shaped scale rod is externally provided with a longitudinal arc-shaped sleeve, the longitudinal arc-shaped sleeve is connected with the transverse arc-shaped scale rod, and the longitudinal arc-shaped scale rod is matched with the longitudinal arc-shaped sleeve and can freely slide in the longitudinal arc-shaped sleeve.

7. The circle-center-sphere-center universally-adjustable rotation radius offset minimally invasive sacroiliac screw guide of claim 1, wherein: still include offside fixing device, offside fixing device includes fixed block and screw thread nail, and the fixed block divide into haplopore fixed block and diplopore fixed block, is equipped with about on the haplopore fixed block penetrating square connecting hole and upper and lower penetrating ilium fixed orifices, all is equipped with locking member on square connecting hole and ilium fixed orifices, controls penetrating and two front and back penetrating square connecting holes about being equipped with on the diplopore fixed block, is equipped with locking member on controlling penetrating, front and back penetrating two square connecting holes.

8. The circle-center-sphere-center universally-adjustable radius of rotation offset minimally invasive sacroiliac screw guide of claim 7, wherein: the single-hole fixing blocks are two, the double-hole fixing blocks are one, the threaded nails are two, and the threaded nails can penetrate through the ilium fixing holes in the single-hole fixing blocks, drill into the opposite ilium and are locked by the locking members in the ilium fixing holes.

9. The circle-center-sphere-center universally-adjustable rotation radius offset minimally invasive sacroiliac screw guide of claim 1, wherein: still include horizontal square connecting rod and vertical square connecting rod, the one end of horizontal square connecting rod is connected with the square connecting hole on the locator body, the other end passes the square connecting hole of first haplopore fixed block and the penetrating square connecting hole of controlling of diplopore fixed block is connected, and by the locking member locking on the three square connecting hole, vertical square connecting rod one end is connected with the penetrating square connecting hole around the diplopore fixed block, the other end is connected with the square connecting hole of second haplopore fixed block, and by the locking member locking on two square connecting holes.

10. The circle-center-sphere-center universally-adjustable rotation radius offset minimally invasive sacroiliac screw guide of claim 1, wherein: the plane of the transverse arc-shaped scale rod is vertical to the plane of the longitudinal arc-shaped scale rod; and the horizontal arc-shaped scale rod and the longitudinal arc-shaped scale rod have the same rotating radius and the common sphere center.

Technical Field

The invention belongs to the technical field of medical instruments, and relates to a minimally invasive sacroiliac screw guider capable of fixing a circle center and a sphere center and adjusting a rotation radius offset in a universal mode.

Background

The injury of the posterior pelvic ring such as the dislocation of the sacroiliac joint and the fracture around the sacroiliac joint can cause the rotational instability and the vertical instability of the pelvis, and the superior method for realizing the fixation of the posterior pelvic ring is to implant sacroiliac screws in a patient body. In recent years, both clinical and biomechanical studies of pelvic fixation have demonstrated: the sacroiliac screw enters from the posterior lateral aspect of the ilium ala, passes through the sacroiliac joint and enters the middle upper part of the sacrum 1 or sacrum 2 vertebral body, and is a good internal fixation type. The percutaneous minimally invasive sacroiliac screw implantation can effectively reduce intraoperative hemorrhage, operative trauma and various complications, and becomes the first choice of clinical orthopedics doctors.

The core technology and the operation difficulty of the sacroiliac joint screw are that the guide pin and the screw are placed, the current sacroiliac joint screw is placed mostly by hands under the perspective of a C-arm X-ray machine, and the sacroiliac joint screw has the following defects: 1. in the process of nail placement, multi-angle X-ray repeated perspective is needed, the positioning is inaccurate, the stability is poor, and if a satisfactory fixed position cannot be achieved after multiple attempts, the fixed holding force is greatly reduced due to the damage of the guide pin to the bone structure. 2. Since the screw is fixed across the joint and needs to pass through 3 layers of cortical bone, accurate positioning of the point of insertion is extremely difficult. 3. The sacrum is anatomically tilted backwards, the sacroiliac screw has a certain angle in the transverse plane and the sagittal plane, and the individual difference is large, so the running direction of the screw is difficult to be accurately determined. 4. The length of the screw is preferably such that it does not break through the cortical bone of the contralateral sacrum, which is difficult to determine accurately by fluoroscopy. 5. The anterior part of the screw is adjacent to the iliac vessels, the posterior part of the screw is the cauda equina nerve in the vertebral canal, and the upper part of the screw is the intervertebral disc, so that the screw has slight deviation, not only can not achieve effective fixation, but also is easy to damage important nerves and vessels, and even endangers life. 6. Uncertainty of parameters such as a screw feeding point, an external inclination angle, a head-tail side inclination angle, a screw length, the drilling frequency of a guide pin and the like becomes a bottleneck for restricting the development of scientific researches such as sacroiliac screw biomechanics research, sacroiliac screw placement standardization research and the like for a long time. In summary, the insertion of the screw lacks objective criteria in determining the point of insertion, the direction of travel, the length of the screw, etc., and is not possible to succeed at one time, thus being technically very difficult and challenging.

In the existing sacroiliac screw guiding device, a pedicle screw guiding needle must be firstly drilled into a sacral 1 vertebral body, and then the guiding needle of the sacroiliac screw is drilled into the sacroiliac screw in a point-to-point aiming mode through a connecting rod with the radian of pi/2. The device improves the accuracy and the safety of nail placement to a certain extent, but has the following defects: 1. the guide pin of the pedicle screw of the sacrum 1 must be accurately placed, so that the technical threshold is greatly improved, and meanwhile, the sacrum which is fractured originally is seriously injured; if the sacrum 1 pedicle guide needle cannot be accurately placed in one time, the fixing strength of the sacrum iliac screw can be greatly reduced by repeated operation, and nerve injury is caused. 2. Because the guide pin of the sacroiliac screw takes the direction of the guide pin of the pedicle screw as reference, and the guide pin of the sacroiliac screw has included angles with the sagittal plane and the upper transverse plane of the sacrum and has large individual difference, the included angles (including the inner inclination angle and the head-tail side inclination angle) between the guide pin of the sacroiliac screw and the guide pin of the pedicle screw are difficult to select before and during the operation, and the placement of the guide pin of the sacroiliac screw also has great uncertainty in the actual operation process; thus, the sacroiliac screw can enter the sacrum, but the direction is not necessarily optimal, nor is the length and fixation strength of the screw necessarily optimal. 3. In the case of sacral pedicle fractures, it cannot be used. 4. The device cannot be used with sacroiliac screws for the sacral 2 and other segments.

In the prior art, a sighting device which only depends on anatomical marks of lumbar vertebrae and pelvis, has no obvious damage to vertebral pedicle, has low technical threshold, can randomly adjust the angle according to individual difference of patients, is simple and convenient to operate and can accurately place the sacroiliac screw guide pin at one time is lacked.

Disclosure of Invention

The invention aims to provide a minimally invasive sacroiliac screw guider with fixed circle center and spherical center and universal adjustment of rotating radius offset, which combines a rectangular main positioner with a transverse arc-shaped adjuster, can realize the functions of determining a screw feeding point according to different disease conditions of a patient, adjusting the inserting direction of sacroiliac screws and accurately inserting the sacroiliac screws at one time, and solves the problems in the prior art. The use of the transverse arc regulator enables a doctor to freely regulate the scales on the transverse arc scale rod inserted into the transverse arc slideway according to the anatomical structure and different disease conditions of a patient so as to match the included angle between the sacroiliac screw and the sagittal plane of a human body on the transverse section and enable the extension line of the sacroiliac screw nail track to pass through the virtual rotation circle center or the virtual rotation sphere center O point, so that the internal inclination angle of the sacroiliac screw can be accurately determined.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a minimally invasive sacroiliac screw guider with a fixed circle center and a ball center and capable of universally adjusting the rotating radius offset comprises a rectangular main positioner, a transverse arc-shaped adjuster, a hollow positioning rod and a hollow guiding controller.

The rectangular main positioner comprises a positioner body and a transverse arc-shaped sleeve arranged at the front end of the positioner body, wherein a sacrum positioning hole and an ilium fixing hole which are through up and down are formed in the positioner body, the sacrum positioning hole is used for being inserted by the guide pin and plays a guiding role for the guide pin, the rectangular main positioner can be fixed to the ilium through the ilium fixing hole through threaded nails, and locking members are arranged on the sacrum positioning hole and the ilium fixing hole.

The transverse arc regulator comprises a transverse arc scale rod and a guider arranged at the left end of the transverse arc scale rod; the transverse arc-shaped scale rod penetrates through the transverse arc-shaped sleeve and can slide in the transverse arc-shaped sleeve; the scales are arranged on the transverse arc-shaped scale rod, the scales inserted into the transverse arc-shaped scale rod of the transverse arc-shaped slide way can be freely adjusted according to the anatomical structure and different disease conditions of a patient to match the included angle between the sacroiliac screw and the sagittal plane of a human body on the cross section, and the extension line of the sacroiliac screw nail track passes through a virtual rotation circle center O point or a virtual rotation sphere center O point, so that the internal inclination angle of the sacroiliac screw can be accurately determined.

The hollow positioning rod is arranged on the rectangular main positioner, a detachably connected threaded guide pin is arranged in the hollow positioning rod, and the hollow positioning rod can be movably inserted into the sacrum positioning hole and can be locked by a locking component on the sacrum positioning hole. The hollow positioning rod is matched with the thread guide pin to be inserted into a sacrum positioning hole on the positioner body to penetrate into the skin, the tip end of the hollow positioning rod is tightly attached to the outer side of an upper articular process of a first sacrum, which is sunken on the cortical bone surface (the point where the hollow positioning rod is tightly attached is A point) or the bone surface of other key anatomical marks, and the thread guide pin can be screwed into the sacrum to stabilize the hollow positioning rod and can also not be screwed into the sacrum. Avoiding cumbersome and risky procedures that must rely on pedicle screws of the sacrum as a reference. A virtual straight line which is parallel to the sagittal plane and vertically enters the inner part of the sacrum downwards is made through the point A, a certain distance below the point A is selected to be a point O on the virtual straight line (the point O is a virtual rotating circle center or a virtual rotating sphere center and is positioned in the sacrum and the middle point of the front cortical bone and the front wall of the sacrum in front of the sacrum on an AO connecting line), the distance from the point A to the point O is a stagger distance, and the stagger distance can be set by adjusting scales on a hollow positioning rod inserted into a positioning hole of the sacrum during operation. And thereby the precise location of a virtual center of rotation or virtual sphere of rotation O-point (also the point through which the sacroiliac screw and guide pin must pass) within the sacrum.

The hollow guide controller comprises a hollow sleeve, and the hollow sleeve is arranged on the guide.

The top surface of the transverse arc-shaped sleeve is arranged horizontally or forwards and downwards inclined relative to the top surface of the locator body, and the top surface of the transverse arc-shaped sleeve is horizontal, so that the circle center of the transverse arc-shaped scale rod is adjusted to be a virtual rotation circle center O point in a matching manner, and a doctor can adjust the scales inserted into the transverse arc-shaped scale rod of the transverse arc-shaped sleeve according to different disease conditions of a patient so as to determine the internal inclination angle of the sacroiliac screw guide pin and the embedding direction of the sacroiliac screw. The top surface of the transverse arc-shaped sleeve is downwards inclined forwards so as to match the circle center of the longitudinal arc-shaped scale rod to be adjusted to a virtual rotating sphere center O point, so that a doctor can adjust the scales on the transverse arc-shaped scale rod and the longitudinal arc-shaped scale rod inserted into the transverse arc-shaped slide way and the longitudinal arc-shaped slide way according to different disease conditions of a patient so as to determine the internal inclination angle and the head-tail side inclination angle of the sacroiliac screw guide pin and further determine the embedding direction of the sacroiliac screw.

The technical scheme is that a left and right penetrating transverse arc-shaped slide way is arranged in the transverse arc-shaped sleeve, the radian of the transverse arc-shaped slide way is consistent with that of the transverse arc-shaped scale rod, and scales are arranged on the surface of the transverse arc-shaped scale rod.

The technical scheme is that the upper part and the lower part of the hollow positioning rod are both cylindrical, the diameter of the lower part of the hollow positioning rod is smaller than that of the upper part of the hollow positioning rod, scales are arranged on the outer surface of the cylindrical upper part of the hollow positioning rod, and the position of a rotation center (a virtual rotation circle center or a virtual rotation sphere center) can be accurately set through the scales on the outer surface of the upper part of the hollow positioning rod.

The technical scheme is that the guider is a guide block or a longitudinal arc-shaped scale rod; the hollow sleeve penetrates through the guide block and then is movably arranged on the guide block or is arranged on the longitudinal arc-shaped scale rod through the sliding block, and scales are arranged on the surface of the longitudinal arc-shaped scale rod. The guide block and the slide block are internally provided with open chutes which are through from left to right and open downwards, the open chutes are provided with locking members, the hollow sleeve penetrates through the open chutes of the guide block and can slide in the guide block; the hollow sleeve penetrates through the opening sliding groove of the sliding block and can slide in the sliding block. The hollow sleeve is used for inserting the opening sliding groove of the guide block or the sliding block to reach the rear outer side of the iliac wing to play a role in positioning and guiding, and the extension line of the inserting direction of the hollow sleeve passes through the rotating spherical center O point.

The technical scheme is that a longitudinal arc-shaped sleeve is further arranged outside the longitudinal arc-shaped scale rod and is connected with the transverse arc-shaped scale rod, and the longitudinal arc-shaped scale rod is matched with the longitudinal arc-shaped sleeve and can freely slide in the longitudinal arc-shaped sleeve. A longitudinal arc-shaped slide way which is through from front to back is arranged in the longitudinal arc-shaped sleeve, and the longitudinal arc-shaped scale rod freely slides in the longitudinal arc-shaped sleeve through the longitudinal arc-shaped slide way. The longitudinal arc-shaped scale rod is also provided with scales, the scales inserted into the longitudinal arc-shaped scale rod of the longitudinal arc-shaped slide way can be freely adjusted according to the anatomical structure and different disease conditions of a patient to match the included angle between the sacroiliac screw and the plane above the sacrum on the coronal plane, and the extension line of the sacroiliac screw nail track passes through the virtual rotation sphere center O point, so that the head side or tail side inclination angle of the sacroiliac screw can be accurately determined, and the inserting direction of the sacroiliac screw can be determined.

Further technical scheme is, still include offside fixing device, offside fixing device includes fixed block and screw thread nail, and the fixed block divide into haplopore fixed block and diplopore fixed block, is equipped with on the haplopore fixed block about penetrating square connecting hole and upper and lower penetrating ilium fixed orifices, all is equipped with locking member on square connecting hole and ilium fixed orifices, is equipped with about penetrating and two square connecting holes penetrating around with on the diplopore fixed block, is equipped with locking member on controlling penetrating, two square connecting holes penetrating around.

The further technical scheme is that the number of the single-hole fixing blocks is two, the number of the double-hole fixing blocks is one, the number of the threaded nails is two, and the threaded nails can penetrate through the ilium fixing holes in the single-hole fixing blocks, drill into the opposite ilium and are locked by the locking members in the ilium fixing holes.

The technical scheme is that the positioner comprises a positioner body, and is characterized by further comprising a transverse square connecting rod and a longitudinal square connecting rod, wherein one end of the transverse square connecting rod is connected with a square connecting hole in the positioner body, the other end of the transverse square connecting rod penetrates through the square connecting hole in the first single-hole fixing block to be connected with left and right through square connecting holes in the double-hole fixing block and is locked by a locking component in the three square connecting holes, one end of the longitudinal square connecting rod is connected with the front and back through square connecting holes in the double-hole fixing block, the other end of the longitudinal square connecting rod is connected with the square connecting hole in.

The technical scheme is that the plane of the transverse arc-shaped scale rod is vertical to the plane of the longitudinal arc-shaped scale rod; and the horizontal arc-shaped scale rod and the longitudinal arc-shaped scale rod have the same rotating radius and the common sphere center.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention has simple structure, low cost and convenient use,

2. the invention does not need multi-angle X-ray repeated fluoroscopy and does not need to puncture into the bone, has accurate positioning and strong stability, and ensures the one-time success of the safe implantation of the guide pin and the screw.

3. The hollow positioning rod is matched with the thread guide pin to penetrate into skin, the tip end of the hollow positioning rod is tightly attached to the outer side of the upper articular process of the first sacrum and is sunken on cortical bone or the surface of bone of other key anatomical marks, and the thread guide pin can be screwed into the sacrum to stabilize the hollow positioning rod and can also not be screwed into the sacrum. Avoiding cumbersome and risky procedures that must rely on pedicle screws of the sacrum as a reference.

4. The use of the transverse arc regulator enables a doctor to freely regulate the scales on the transverse arc scale rod inserted into the transverse arc slideway according to the anatomical structure and different disease conditions of a patient so as to match the included angle between the sacroiliac screw and the sagittal plane of a human body on the transverse section and enable the extension line of the sacroiliac screw nail track to pass through the virtual rotation circle center or the virtual rotation sphere center O point, so that the internal inclination angle of the sacroiliac screw can be accurately determined.

5. The use of the longitudinal arc-shaped scale rod enables a doctor to freely adjust the scale on the longitudinal arc-shaped scale rod inserted into the longitudinal arc-shaped slide way according to the anatomical structure and different disease conditions of a patient to match the included angle between the sacroiliac screw and the plane above the sacrum on the coronal plane and enable the extension line of the sacroiliac screw nail track to pass through the virtual rotation sphere center O point, so as to accurately determine the head side or tail side inclination angle of the sacroiliac screw and determine the inserting direction of the sacroiliac screw.

6. The circle center-fixed rotation radius offset-minimally invasive sacroiliac screw positioning guider has a simpler structure, and can be used for cases in which only sacroiliac screws need to be placed in sacrum and the head-tail side inclination angle is not considered. The sphere centering rotation radius offset-minimally invasive sacroiliac screw positioning guider can accurately set all parameters of the internal inclination angle, the head side or tail side inclination angle of the sacroiliac screw, the position of the virtual rotation circle center in the sacrum, the rotation radius offset, the screw feeding point, the screw length and the like, and can ensure that the sacroiliac screw is successfully and accurately placed at one time according to preoperative design; therefore, the surgical instrument is not only suitable for clinical operation, but also can completely meet the requirements of scientific research.

Drawings

Fig. 1 is a schematic view of a combined structure of a rectangular main positioner and a transverse arc adjuster according to embodiment 1 of the present invention.

Fig. 2 is a schematic structural diagram of a rectangular main positioner according to embodiment 1 of the present invention.

Fig. 3 is a schematic structural view of a lateral arc adjuster according to embodiment 1 of the present invention.

Fig. 4 is a use state diagram of embodiment 1 of the present invention.

Fig. 5 is a partially enlarged view of B in fig. 4.

Fig. 6 is a contralateral fixation device of the present invention.

FIG. 7 is a schematic structural diagram of the hollow sleeve, the hollow positioning rod and the threaded guide pin according to the present invention.

Fig. 8 is a schematic view of a combined structure of a rectangular main positioner and a transverse arc adjuster according to embodiment 2 of the present invention.

Fig. 9 is a schematic structural diagram of a rectangular main positioner according to embodiment 2 of the present invention.

FIG. 10 is a left side view of a rectangular main retainer according to embodiment 2 of the present invention.

Fig. 11 is a usage state diagram of embodiment 2 of the present invention.

Fig. 12 is a partial enlarged view of B of fig. 11.

In the figure: 1. a locator body; 2. a sacral locating hole; 3. a hollow positioning rod; 4. a threaded guide pin; 5. an ilium fixation hole; 6. a threaded nail; 7. locking the bolt; 8. a transverse arcuate sleeve; 9. a transverse arc-shaped scale bar; 10. a locking hole; 11. a hollow sleeve; 12. an open chute; 13. a guide block or slide; 14. the ilium; 15. a sacrum; 16. a square connecting hole; 17. a transverse square connecting rod; 18. a double-hole fixing block; 19. a single-hole fixing block; 20. a longitudinal square connecting rod; 21. a transverse arc-shaped slideway; 22. connecting blocks; 23. a longitudinal arc-shaped scale bar; 24. a longitudinal arcuate sleeve; 25. a longitudinal arc-shaped slideway.

Detailed Description

In order to better understand the technical content of the invention, specific embodiments are provided below, and the invention is further described with reference to the accompanying drawings.