Adjustable reset screw

Abstract

This utility model relates to the field of medical device technology and provides an adjustable reset screw, comprising: a screw body; a connector with an internal mounting groove and a first opening and a second opening communicating with the mounting groove at both axial ends; a lower pressure block slidably connected in the mounting groove, with the end of the screw body ball-jointed to the lower pressure block; an upper pressure block slidably connected in the mounting groove, one end of the upper pressure block being spaced apart from the lower pressure block, and the other end protruding through the second opening for mounting a connecting rod; an elastic support body elastically supporting the upper and lower pressure blocks; and a limiting structure for connecting the upper pressure block and the connector and limiting the sliding distance of the upper pressure block in the mounting groove. With this configuration, the two micro-motion units combined enable multi-dimensional dynamic adjustment, meeting the needs of flexible spinal movements in flexion, extension, lateral bending, and rotation, reducing the load on adjacent segments, and further reducing the risk of degeneration in adjacent segments.

Description

Technical Field

[0001] This utility model relates to the field of medical device technology, and in particular to an adjustable reset screw. Background Technology

[0002] In modern medicine, lumbar disc herniation and lumbar spinal stenosis are two common spinal diseases that cause great pain and inconvenience to patients. Currently, posterior fusion fixation surgery, which involves removing the herniated disc and widening the narrowed nerve root canal, is a common surgical procedure in spinal surgery. Pedicle screws and connecting rods are key components of the internal fixation system.

[0003] However, traditional surgical methods often impair the mobility of the lumbar spine or accelerate the damage to adjacent discs, with the degeneration rate of adjacent segments reaching as high as 52.5%. To address the contradiction between maintaining vertebral stability and restoring mobility in the treatment of lumbar disc herniation, dynamic internal fixation systems have emerged, such as the Cosmic dynamic internal fixation system (Ulrich). It consists of a screw and a hinge structure, with the hinge located between the screw head and the screw body, allowing a range of motion of 20° above and below the sagittal plane. In clinical practice, this internal fixation system can preserve a certain degree of spinal movement and, to some extent, prevent or delay the degeneration of adjacent segments.

[0004] However, the movement of the spine involves a variety of complex movements such as flexion, extension, rotation and circumduction. In addition, there is narrowing and widening of the intervertebral space between the upper and lower vertebrae, as well as anterior and posterior displacement and rotation between the vertebrae. Traditional internal fixation systems obviously cannot meet the needs of flexible spinal movement and still face a significant risk of adjacent segment degeneration.

[0005] Therefore, how to maintain spinal stability while meeting the need for flexible movement and further reducing the risk of adjacent segment degeneration has become an important issue that urgently needs to be addressed. Utility Model Content

[0006] This invention provides an adjustable reset screw to address the shortcomings of existing pedicle screws, which are unable to meet the needs of flexible spinal movement and have a high risk of degeneration in adjacent segments. The screw can achieve multi-dimensional dynamic adjustment to meet the flexible and complex movement needs of the spine and further reduce the problem of degeneration in adjacent segments.

[0007] This utility model provides an adjustable reset screw, comprising:

[0008] Screw body;

[0009] The connector has an internal mounting groove and a first opening and a second opening that communicate with the mounting groove at both axial ends.

[0010] The lower pressure block is slidably connected to the mounting groove along the axial direction of the connector, and the screw body passes through the first opening and its end is ball-jointed with the lower pressure block;

[0011] The upper pressure block is slidably connected to the mounting groove along the axial direction of the connector. One end of the upper pressure block is arranged at a distance from the lower pressure block, and the other end is exposed through the second opening for mounting the connecting rod.

[0012] An elastic support body is elastically supported between the upper pressure block and the lower pressure block;

[0013] A limiting structure is used to connect the upper pressure block and the connector, and to limit the sliding distance of the upper pressure block within the mounting groove.

[0014] According to the present invention, an adjustable reset screw is provided with a ball head at the end of the screw body, and the first opening is a stepped hole;

[0015] The pressing block has a concave surface on the side facing the first opening. The concave surface is a spherical cap surface and is adapted to the ball head. The ball head is pressed against the first opening by the concave surface.

[0016] According to the present invention, an adjustable reset screw is provided in which the inner wall of the first opening is configured as a spherical crown surface adapted to the ball head, and the ball head contacts the spherical surface of the inner wall of the first opening.

[0017] According to the present invention, an adjustable reset screw is provided, wherein the elastic support body includes a compression spring, and the two ends of the compression spring elastically abut against the upper pressure block and the lower pressure block respectively.

[0018] According to the adjustable reset screw provided by this utility model, the limiting structure includes:

[0019] A limiting groove is provided in one of the upper pressure block and the connector;

[0020] A limiting pin is connected to the other of the upper pressure block and the connector, and its end is embedded in the limiting groove; the limiting groove has a margin allowing the limiting pin to move in the axial direction of the connector.

[0021] According to the present invention, an adjustable reset screw is provided, wherein the limiting groove is disposed on the outer peripheral surface of the upper pressure block, and the limiting pin is connected to the connector.

[0022] According to the present invention, an adjustable reset screw is provided, wherein the connector is provided with a pin hole that radially passes through the mounting groove, and the limiting pin passes through the pin hole.

[0023] According to the present invention, an adjustable reset screw is provided, wherein the pin hole is a countersunk hole, and the head of the limiting pin is recessed into the pin hole.

[0024] According to the present invention, an adjustable reset screw is provided, wherein the upper pressure block is provided with an open connecting groove at one end away from the lower pressure block, the connecting groove extends radially along the connector and passes through the opposite sides of the lower pressure block, for the insertion of the connecting rod;

[0025] It also includes a locking structure for locking the connecting rod into the connecting groove.

[0026] According to the adjustable reset screw provided by this utility model, the locking structure includes:

[0027] A threaded sleeve is coaxially connected to one end of the connector that has a second opening; the threaded sleeve has axially extending notches on both sides along the extension direction of the connecting groove, one end of the notch is in communication with the connecting groove, and the other end is through the other end of the threaded sleeve relative to the connecting groove.

[0028] A screw plug, threadedly connected to the screw sleeve, is used to press the connecting rod into the connecting groove.

[0029] The adjustable reset screw provided by this utility model comprises a connector, an upper pressure block, and a limiting structure, forming one micro-motion unit. The screw body is ball-jointed with the lower pressure block, and an elastic support body creates a certain movement gap between the lower and upper pressure blocks, thus forming a second micro-motion unit. The first micro-motion unit allows the connecting rod connected to the upper pressure block to make slight adjustments along the axial direction of the connector, while the second micro-motion unit allows the screw body to make a slight omnidirectional oscillation relative to the connector around the ball-joint point. Simultaneously, the lower pressure block provides the screw body with displacement along the axial direction of the connector, thereby adjusting the screw's center of motion in real time to match the rotation center of the vertebral bodies' mutual movement. The combination of the two micro-motion units enables multi-dimensional dynamic adjustment, meeting the needs of flexible spinal movements in flexion, extension, lateral bending, and rotation, reducing the load on adjacent segments, and further reducing the risk of degeneration in adjacent stages. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 This is an overall view of the adjustable reset screw provided in this embodiment of the utility model.

[0032] Figure 2 This is a top view of the adjustable reset screw provided in this embodiment of the utility model.

[0033] Figure 3 yes Figure 2 Cross-sectional view along the AA direction.

[0034] Figure 4 This is a schematic diagram showing the cooperation of various components in the adjustable reset screw provided in this embodiment of the utility model.

[0035] Figure 5 This is a schematic diagram showing the cooperation between the ball head and the upper and lower pressure blocks provided in this embodiment of the utility model.

[0036] Figure 6 This is a schematic diagram of the structure of the adjustable reset screw and the connecting rod provided in the embodiment of this utility model.

[0037] Figure label:

[0038] 10. Screw body; 100. Ball head; 11. Connector; 110. Mounting groove; 111. First opening; 112. Pin hole; 12. Lower pressure block; 120. Concave surface; 13. Upper pressure block; 130. Connecting groove; 14. Elastic support body; 15. Limiting structure; 150. Limiting groove; 151. Limiting pin; 16. Screw sleeve; 160. Notch; 17. Screw plug; 20. Connecting rod. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0040] To better understand the adjustable reset screw provided in this embodiment of the invention, its application background is first introduced. Pedicle screws and connecting rods are key components of the fixation system in spinal fusion fixation surgery.

[0041] To maintain vertebral stability while preserving its mobility and reducing the risk of degeneration in adjacent segments, dynamic internal fixation systems have been widely used. Traditional pedicle screws consist of a rod and a hinge structure, with the hinge located between the screw head and the screw body, allowing a range of motion of 20° above and below the sagittal plane. Based on years of clinical results, this internal fixation system can preserve a certain degree of spinal movement and, to some extent, prevent or delay degeneration of adjacent segments.

[0042] However, spinal movement involves a variety of complex movements such as flexion, extension, rotation, and circumduction. In addition, there is narrowing and widening of the intervertebral space between the upper and lower vertebrae, as well as anterior and posterior displacement and rotation between the vertebrae. Studies have shown that the range of motion of lumbar flexion and extension is approximately 100-140 degrees, while the range of motion of lateral flexion and rotation is between 40-70 degrees. Traditional internal fixation systems obviously cannot meet the needs of flexible spinal movement and still have many potential complications such as poor fusion, bone graft collapse, excessive stress concentration in adjacent segments, pain in the donor site, loosening or breakage of fusion devices, and pseudoarthrosis after fusion. They also face a significant risk of degeneration in adjacent segments.

[0043] In view of this, the present invention provides an adjustable reset screw that can meet the flexible and complex movement requirements of the spine and further reduce the risk of degeneration in the near future.

[0044] The following is combined Figures 1 to 6 This invention describes an adjustable reset screw.

[0045] Reference Figures 1 to 5 An adjustable reset screw includes a screw body 10, a connector 11, a lower pressure block 12, an upper pressure block 13, an elastic support body 14, and a limiting structure 15. The connector 11 has a mounting groove 110 and two openings 111 and 12 respectively at its axial ends, both communicating with the mounting groove 110. The lower pressure block 12 is slidably connected to the mounting groove 110 along the axial direction of the connector 11. The screw body 10 passes through the first opening 111, with one end of the screw body 10 in the mounting groove 110 ball-jointed to the lower pressure block 12, and the other end connected to the first opening 111. The opening 111 extends out of the mounting groove 110 and forms a pointed tip; the upper pressure block 13 is slidably connected to the mounting groove 110 along the axial direction of the connector 11, one end of the upper pressure block 13 is arranged at a distance from the lower pressure block 12, and the other end protrudes from the second opening for mounting the connecting rod 20; the elastic support body 14 is elastically supported between the lower pressure block 12 and the upper pressure block 13, so that there is a margin for movement between the two along the axial direction of the connector 11; the limiting structure 15 is used to connect the upper pressure block 13 and the connector 11, and to limit the sliding distance of the upper pressure block 13 in the mounting groove 110.

[0046] In detail, the connector 11, upper pressure block 13, and limiting structure 15 of the reset screw constitute one micro-motion unit; the screw body 10 is ball-jointed with the lower pressure block 12, and the elastic support body 14 creates a certain movement gap between the lower pressure block 12 and the upper pressure block 13, thus constituting a second micro-motion unit; the first micro-motion unit allows the connecting rod 20 connected to the upper pressure block 13 to make slight adjustments in the axial direction of the connector 11, while the second micro-motion unit allows the screw body 10 to make a slight omnidirectional swing relative to the connector 11 around the ball joint point. At the same time, the lower pressure block 12 can provide the screw body 10 with a displacement along the axial direction of the connector 11, thereby adjusting the screw's center of motion in real time to match the rotation center of the vertebral bodies. The combination of the two micro-motion units can achieve multi-dimensional dynamic adjustment, meeting the needs of the spine for flexible movements in flexion, extension, lateral bending, and rotation, reducing the load on adjacent segments, and further reducing the risk of degeneration in adjacent stages.

[0047] It is understood that the material, size, and other parameters of the adjustable reset screw can be selected and designed according to actual needs, and no specific limitations are imposed in this embodiment of the utility model.

[0048] In one example of this utility model, the connector 11 is a hollow columnar structure with its inner cavity formed as the aforementioned mounting groove 110. The first opening 111 and the second opening respectively define the two ends of the connector 11. The second opening is an open opening, which allows the upper pressure block 13 to be exposed in the mounting groove 110 to install the connecting rod 20. The first opening 111 is set as a stepped hole.

[0049] A ball head 100 is connected to the other end of the screw body 10 relative to its tip. Specifically, the ball head 100 can be integrally formed on the end of the screw body 10. The side of the pressure block 12 facing the first opening 111 has a concave surface 120, which is a spherical crown surface and is adapted to the ball head 100. Under the preload of the elastic support body 14, the ball head 100 is pressed against the first opening 111 by the concave surface 120 of the pressure block 12. With this configuration, the concave surface 120 and the spherical surface of the ball head 100 make contact and fit, which can both restrict the position of the ball head 100 and allow the ball head 100 to rotate flexibly in three-dimensional space, thereby realizing the ball joint between the screw body 10 and the pressure block 12.

[0050] In a further example of this utility model, the inner wall of the first opening 111 is configured as a spherical crown surface adapted to the ball head 100, and the ball head 100 contacts the spherical surface of the inner wall of the first opening 111. With this configuration, under the preload of the elastic support 14, the ball head 100 is pressed between the spherical crown-shaped concave surface 120 of the lower pressure block 12 and the spherical crown-shaped inner wall of the first opening 111. The two work together to limit and support the ball head 100, which can effectively improve the smoothness and stability of the rotation of the ball head 100, thereby realizing the smooth and stable rotation of the screw body 10.

[0051] It should be noted that the swing angle range of the screw body 10 can be designed according to actual needs, and the limitation of the swing angle range of the screw body 10 can be achieved through various known methods such as mechanical limiting and control of the geometric parameters of the ball joint itself. For example, a stop can be radially protruded from the part of the screw body 10 near the first opening 111. When the screw body 10 swings to a certain angle, the stop abuts against the end face of the connector 11, thereby limiting the continued swing of the screw body 10. Alternatively, the angle can be controlled by adjusting parameters such as the spherical radius, eccentricity, and shape of the ball head 100 so that the ball head 100 is constrained by the spherical crown concave surface 120 and the inner wall of the first opening 111 during rotation. For example, if the first opening 111 is set to be elliptical, the screw body 10 will be constrained by the major and minor axes of the first opening 111 after passing through the first opening 111, thereby constraining the swing of the screw body 10 within an elliptical range and controlling the swing angle range of the screw body 10. Of course, the above are just examples, and other methods will not be listed and described in detail in this embodiment of the utility model.

[0052] In a further example of this utility model, the upper pressure block 13 and the lower pressure block 12 are arranged at intervals relative to each other, and the elastic support body 14 is supported between the upper pressure block 13 and the lower pressure block 12, so that the upper pressure block 13 and the lower pressure block 12 have the margin to move along the axial direction of the connector 11. When the spine performs flexion and extension movements, the screw body 10, except for a slight universal swing around the ball joint point relative to the connector 11, slides the lower pressure block 12 to provide the screw body 10 with the displacement along the axial direction of the connector 11, adjusts the center of motion of the screw body 10 in real time, adapts to the rotation center of the mutual movement of the vertebrae of the spine, and reduces the load on adjacent segments.

[0053] The elastic support 14 can be made of compression spring, elastic sheet or other materials with elastic modulus, as long as it can meet the required mechanical performance requirements, deformation requirements and biocompatibility requirements.

[0054] In this embodiment, the elastic support 14 is a compression spring, and the two ends of the compression spring elastically abut against the upper pressure block 13 and the lower pressure block 12, respectively.

[0055] Through the above technical solution, after the damaged lumbar disc is removed, the adjacent vertebrae are fixed by the adjustable repositioning screws and connecting rods 20 to maintain the original vertebral height. At the same time, with the cooperation of the connector 11, ball head 100, lower pressure block 12, elastic support body 14 and other structures, elastic fixation and micro-universal swing are achieved, allowing the vertebrae to maintain a rotation range of 4-8 degrees after surgery, reducing the load on the lumbar region and ensuring stability and flexibility.

[0056] The upper pressure block 13 and its connection method with the connector 11 will be described in detail below with reference to the accompanying drawings.

[0057] Reference Figure 4 and Figure 5 The upper pressure block 13 is confined within the mounting groove 110 by a limiting structure 15. The limiting structure 15 specifically includes a limiting groove 150 and a limiting pin 151. The limiting groove 150 is located on one of the upper pressure block 13 and the connector 11; the limiting pin 151 is connected to the other of the upper pressure block 13 and the connector 11, and the end of the limiting pin 151 is embedded in the limiting groove 150. In the axial direction of the connector 11, the limiting groove 150 has a margin allowing the limiting pin 151 to move. This configuration, through the fitted limiting groove 150 and the limiting pin 151, not only confines the upper pressure block 13 within the mounting groove 110 to prevent parts from falling out, but also allows the upper pressure block 13 a certain adjustment margin in the axial direction of the connector 11, thereby driving the connecting rod 20 locked on the upper pressure block 13 to perform fine adjustments.

[0058] In a further example of this utility model, the limiting groove 150 is disposed on the outer peripheral surface of the upper pressure block 13, and the limiting pin 151 is connected to the connector 11.

[0059] In detail, the connector 11 is provided with a pin hole 112 that runs radially through the mounting groove 110, and the limiting pin 151 passes through the pin hole 112.

[0060] More specifically, the limit pin 151 can be a threaded pin, and the pin hole 112 is set as a threaded hole, so as to facilitate the connection of the limit pin 151 on the connector 11.

[0061] In a further example of this invention, the pin hole 112 is configured as a countersunk hole, with the head of the limiting pin 151 recessed into the pin hole 112. This configuration ensures that the outer surface of the connector 11 is flat, avoiding any adverse effects on the surgical procedure or postoperative recovery.

[0062] To facilitate the connection between the connecting rod 20 and the upper pressure block 13, in one example of this invention, the upper pressure block 13 has an open connecting groove 130 at the end away from the lower pressure block 12. The connecting groove 130 extends radially along the connector 11 and passes through the opposite sides of the lower pressure block 12, making the connecting groove 130 have an overall U-shaped structure. The connecting rod 20 is arranged along the extending direction of the connecting groove 130 and is pressed into the connecting groove 130 through the upper opening, thereby achieving the positioning of the connecting rod 20 in the connecting groove 130. The adjustable reset screw also includes a locking structure for locking the connecting rod 20 in the connecting groove 130.

[0063] In a further example of this utility model, refer to Figure 6The locking structure includes a threaded sleeve 16 and a threaded plug 17. The threaded sleeve 16 is coaxially connected to one end of the connector 11 with a second opening. The threaded sleeve 16 has axially extending notches 160 on both sides along the extending direction of the connecting groove 130. One end of the notch 160 communicates with the connecting groove 130, and the other end passes through the other end of the threaded sleeve 16 opposite to the connecting groove 130, making the threaded sleeve 16 have a U-shaped structure. The threaded plug 17 is threadedly connected to the threaded sleeve 16 to press the connecting rod 20 into the connecting groove 130.

[0064] With this configuration, when connecting the adjustable reset screw and the connecting rod 20, the connecting rod 20 passes through the notches 160 on both sides of the screw sleeve 16 and is pressed downward into the connecting groove 130. Then, the screw plug 17 is connected to the screw sleeve 16, and the bottom of the screw plug 17 presses against the connecting rod 20, thereby connecting the connecting rod 20 and the adjustable reset screw.

[0065] In detail, to improve structural strength, the threaded sleeve 16 and the connector 11 can be integrally molded.

[0066] It is understood that the dimensions and specifications of the screw sleeve 16 and the screw plug 17 can be designed according to actual needs, and no specific restrictions are imposed in this embodiment of the utility model.

[0067] It is understood that, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples.

[0068] The reset screw provided in this embodiment of the present invention is assembled by first passing the screw body 10 through the first opening 111 of the connector 11, with the ball head 100 at the end of the screw body 10 located in the mounting groove 110. Then, the lower pressure block 12, the elastic support body 14 and the upper pressure block 13 are placed into the mounting groove 110 in sequence. The limiting pin 151 passes through the pin hole 112 on the connector 11 and is embedded in the limiting groove 150 on the outer periphery of the upper pressure block 13 to achieve the limiting of the upper pressure block 13 in the connector 11.

[0069] Under the preload of the elastic support 14, the ball head 100 is pressed between the spherical concave surface 120 of the lower pressure block 12 and the spherical inner wall surface of the first opening 111, realizing the ball joint connection between the ball head 100 and the lower pressure block 12. The presence of the elastic support 14 provides a certain amount of movement margin between the lower pressure block 12 and the upper pressure block 13, thereby providing a preset displacement along the axial direction of the connector 11 for the overall structure composed of the bolt body and the ball head 100. The active center of the screw is adjusted in real time according to the spinal movement, adapting to the rotation center of the vertebral body of the spine. The mutually cooperating limiting groove 150 and limiting pin 151 can not only restrict the upper pressure block 13 within the mounting groove 110 to prevent the parts from falling out, but also allow the upper pressure block 13 to have a certain adjustment margin in the axial direction of the connector 11, thereby driving the connecting rod 20 locked on the upper pressure block 13 to make micro-adjustments.

[0070] When connecting the adjustable reset screw and the connecting rod 20, the connecting rod 20 is passed through the notches 160 on both sides of the screw sleeve 16 and then pressed down into the connecting groove 130 of the upper pressure block 13. Then, the screw plug 17 is screwed into the screw sleeve 16, and the bottom of the screw plug 17 presses the connecting rod 20 to achieve the connection between the connecting rod 20 and the adjustable reset screw. It should be noted that after the screw plug 17 presses the connecting rod 20, there should still be a certain amount of movement between the lower pressure block 12 and the upper pressure block 13 to ensure that the movement angle of the adjustable reset screw can match the normal vertebral body movement.

[0071] Through the above technical solution, connector 11, upper pressure block 13, and limiting structure 15 constitute one micro-motion unit; screw body 10 is ball-jointed with lower pressure block 12, and elastic support body 14 provides a certain movement gap between lower pressure block 12 and upper pressure block 13, thus constituting a second micro-motion unit; the first micro-motion unit allows connecting rod 20 connected to upper pressure block 13 to make micro-adjustments in the axial direction of connector 11, while the second micro-motion unit allows screw body 10 to make a slight omnidirectional swing relative to connector 11 around the ball joint point. At the same time, lower pressure block 12 can provide screw body 10 with displacement along the axial direction of connector 11, thereby adjusting the screw's center of motion in real time to match the rotation center of the vertebral bodies. The combination of the two micro-motion units can achieve multi-dimensional dynamic adjustment, meeting the needs of flexible spinal movements in flexion, extension, lateral bending, and rotation, reducing the load on adjacent segments, and further reducing the risk of degeneration in adjacent stages.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. An adjustable reset screw, characterized by include: Screw body (10); The connector (11) has an internal mounting groove (110) and a first opening (111) and a second opening that communicate with the mounting groove (110) at both ends of the axial direction. The pressure block (12) is slidably connected to the mounting groove (110) along the axial direction of the connector (11), and the screw body (10) passes through the first opening (111) and its end is ball-jointed with the pressure block (12). The upper pressure block (13) is slidably connected to the mounting groove (110) along the axial direction of the connector (11). One end of the upper pressure block (13) is arranged at a distance from the lower pressure block (12), and the other end is exposed through the second opening for mounting the connecting rod (20). An elastic support (14) is elastically supported between the upper pressure block (13) and the lower pressure block (12); A limiting structure (15) is used to connect the upper pressure block (13) and the connector (11) and to limit the sliding distance of the upper pressure block (13) in the mounting groove (110).

2. The adjustable set screw of claim 1, wherein, The end of the screw body (10) is provided with a ball head (100), and the first opening (111) is a stepped hole; The pressing block (12) has a concave surface (120) on the side facing the first opening (111). The concave surface (120) is a spherical cap surface and is adapted to the ball head (100). The ball head (100) is pressed onto the first opening (111) by the concave surface (120).

3. The adjustable set screw of claim 2, wherein, The inner wall of the first opening (111) is configured as a spherical crown surface that is adapted to the ball head (100), and the ball head (100) is in contact with the spherical surface of the inner wall of the first opening (111).

4. The adjustable set screw of claim 1, wherein, The elastic support (14) includes a compression spring, the two ends of which elastically abut against the upper pressure block (13) and the lower pressure block (12), respectively.

5. The adjustable set screw of any one of claims 1 to 4, wherein, The limiting structure (15) includes: A limiting groove (150) is provided in one of the upper pressure block (13) and the connector (11); A limiting pin (151) is connected to the other of the upper pressure block (13) and the connector (11), and its end is embedded in the limiting groove (150); the limiting groove (150) has a margin allowing the limiting pin (151) to move in the axial direction of the connector (11).

6. The adjustable set screw of claim 5, wherein, The limiting groove (150) is disposed on the outer peripheral surface of the upper pressure block (13), and the limiting pin (151) is connected to the connector (11).

7. The adjustable set screw of claim 6, wherein, The connector (11) is provided with a pin hole (112) that radially passes through the mounting groove (110), and the limiting pin (151) passes through the pin hole (112).

8. The adjustable set screw of claim 7, wherein, The pin hole (112) is a countersunk hole, and the head of the limiting pin (151) is recessed into the pin hole (112).

9. The adjustable set screw of claim 1, wherein, The upper pressure block (13) has an open connecting groove (130) at one end away from the lower pressure block (12). The connecting groove (130) extends radially along the connector (11) and passes through the opposite sides of the lower pressure block (12) for the connecting rod (20) to be inserted. It also includes a locking structure for locking the connecting rod (20) into the connecting groove (130).

10. The adjustable set screw of claim 9, wherein, The locking structure includes: A threaded sleeve (16) is coaxially connected to one end of the connector (11) that has a second opening; the threaded sleeve (16) has axially extending notches (160) on both sides along the extension direction of the connecting groove (130), one end of the notch (160) is in communication with the connecting groove (130), and the other end is through the other end of the threaded sleeve (16) relative to the connecting groove (130); A screw plug (17) is threaded to the screw sleeve (16) to press the connecting rod (20) into the connecting groove (130).

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