Load-bearing type intramedullary nail system with pressurizing function and mounting method

Abstract

The invention relates to a bearable intramedullary nail system with a pressurizing function and an installation method thereof, a first sliding groove and a locking hole are formed in a main nail, the length of the first sliding groove is larger than the width of the first sliding groove, a fixing hole is formed in the end, close to the first sliding groove, of the main nail, the bearable interlocking nail is provided with a second sliding groove, and the second sliding groove is communicated with the locking hole. The length of the second sliding groove is larger than the width of the second sliding groove, the tail end of the pressurizing nail is provided with a threaded structure used for being connected with a first fixed object, and the bearable interlocking nail penetrates through the locking hole of the main nail to be connected with the first fixed object. The pressurizing nail sequentially penetrates through the first sliding groove of the main nail and the second sliding groove of the bearable interlocking nail to be fixedly connected with a first fixed object, and the main nail is fixedly installed on a second fixed object. The fixing device is further provided with a fixing tail cap, the fixing tail cap limits the pressurizing nail through the fixing hole, and the tail cap is made of degradable materials.

Description

Technical Field

[0001] The invention relates to medical surgical equipment, and in particular to a load-bearing intramedullary nail system with a pressurizing function and an installation method. Background Art

[0002] Since elderly patients all have varying degrees of osteoporosis, minor trauma or falls can lead to medullary fractures including femoral neck fractures, intertrochanteric fractures, etc. Therefore, medullary fractures are a common fracture site in the elderly, and the commonly used internal fixation is interlocking intramedullary nail fixation.

[0003] As the core internal fixation technology for modern fracture treatment, interlocking intramedullary nailing, with its long action arm design across the fracture line and the three-dimensional locking mechanism formed by the proximal and distal interlocking screws, significantly improves anti-rotation and longitudinal stability, effectively avoiding fracture shortening and limb length loss. However, the stress shielding effect caused by this technology leads to bone loss in the fixed segment and delayed callus mineralization, which has become a key contradiction restricting its clinical application. In the relevant literature (Early rehabilitation after surgery for distal femoral fracture treated with GSH interlocking intramedullary nailing, China Rehabilitation, April 2004, Vol. 19, No. 2, Hao Zhenhai et al.), stress shielding often leads to stiffness and dysfunction of the healing site. In the existing technology (Effect analysis of early dynamic treatment of lower limb fractures with interlocking intramedullary nailing, Smart Health 2024, No. 2), Tang Weiyong et al. proposed that early dynamic treatment of intramedullary nailing will make patients heal faster and recover better.

[0004] Prior art CN215192132U and CN113925587A disclose proximal triangular femoral intramedullary nails, which utilize a main nail, a first locking nail, and a second locking nail to form a triangular structure to achieve stability of the screw in the femoral head and neck. While fixing the femoral head, the intramedullary nail cannot achieve dynamization in the late stage of fracture healing, thereby prolonging the fracture healing time; Prior art CN1813639A discloses a controllable micro-motion interlocking intramedullary nail, which relates to a controllable micro-motion interlocking intramedullary nail, which provides strong fixation in the early stage of fracture by arranging a degradable bioactive material in the locking hole, generates an axial gap through material degradation in the middle and late stages, provides gradually enhanced stress stimulation, and promotes fracture healing. However, in this technology, the interlocking nail and the main nail are only temporarily fixed by degradable materials, and no mechanical locking structure is designed. Before the degradable material is completely degraded, the interlocking nail is only fixed by the surface friction of the degradable material in the hole. This cooperation lacks stability and cannot achieve the pressurization function in the early stage of healing. The movement of the bone block may cause the interlocking nail to deviate, resulting in the risk of "Z-shaped dislocation". In addition, there is a degradable material between the interlocking nail and the hole wall. When the pressure between the interlocking nail and the hole wall is too large, the degradable material set between the interlocking nail and the hole wall cannot come into contact with the blood, resulting in a situation where it cannot be degraded or the degradation rate of the degradable material is reduced, and it does not degrade as expected, affecting the dynamic process in the middle and late stages of healing. In addition, if the patient bears weight too early or an accidental collision occurs, the coordination stability of the interlocking nail and the main nail may be destroyed, requiring secondary surgical intervention. At present, there is a need for an intramedullary nail that can provide static strong internal fixation in the early stage and can be easily adjusted to dynamic dynamic in the middle and late stages to improve this situation. Summary of the invention

[0005] In order to overcome the shortcomings of intramedullary nail internal fixation technology in the prior art, the present invention proposes a load-bearing intramedullary nail system with a pressurization function, the load-bearing intramedullary nail system comprising a main nail, a pressurization nail and a load-bearing interlocking nail, the main nail is provided with a first sliding groove and a locking hole, the length of the first sliding groove is greater than its width, the main nail is provided with a fixing hole at one end adjacent to the first sliding groove, the load-bearing interlocking nail has a second sliding groove, the length of the second sliding groove is greater than its width, the end of the pressurization nail is provided with a threaded structure for connecting with a first fixed object such as a femoral head, a femoral block, etc., the load-bearing interlocking nail is penetrated through the locking hole of the main nail and is micro-movement / slidingly connected with the first fixed object, the pressurization nail sequentially passes through the first sliding groove of the main nail and the second sliding groove of the load-bearing interlocking nail and is fixedly connected with the first fixed object, the main nail is fixedly installed on the second fixed object such as a femoral body, a femoral neck, etc.; it also has a fixed tail cap, the fixed tail cap limits the pressurization nail through the fixing hole, and the tail cap is made of degradable material. The load-bearing intramedullary nail system of the present invention limits the pressure nail by fixing the pressure nail through the fixed tail cap, so as to realize the pressure function of the first fixed object immediately after the operation is completed. The cooperation between the interlocking nail and the main nail is a mechanical locking structure, and the pressure nail with accurate pressure adjustment amount is combined. During the early healing, there will be no micro-movement between the interlocking nail and the main nail, and thus the first fixed object will not be caused to slide, so that an absolutely strong internal fixation is formed, and static healing in the early stage of fracture healing is realized; when the fixed tail cap is made of degradable material, the fixed tail cap degrades by itself within a certain period of time and is absorbed by the human body, so that the pressure nail loses its limit, and the pressure nail slides up and down in the first sliding groove and the second sliding groove, and the bone block can make limited micro-movement, which produces stress stimulation to the fracture position, promotes the healing of the fracture, and shortens the fracture healing time.

[0006] Preferably, the bottom contour of the second sliding groove is lower than the bottom contour of the first sliding groove, so that the second sliding groove has no limiting effect on the pressure nail, so that the first fixed object can move slightly along the axis of the load-bearing interlocking nail when the pressure nail loses its limiting effect, thereby preventing the first fixed object from healing out of position and promoting fracture healing.

[0007] Preferably, the fixed tail cap applies pressure to the pressurized nail through a threaded structure to limit the position, the fixing hole is provided with a thread, and the fixed tail cap is provided with an external thread, and the pressurized nail is limited by screwing the fixed tail cap into the fixing hole.

[0008] Preferably, the fixing hole is a through hole, the end of the main nail is provided with an external thread, and the fixed tail cap includes a nut and a limiting rod located at the center of the nut, and the limiting rod limits the pressure nail by cooperating with the external thread at the end of the main nail.

[0009] Preferably, when the fixed tail cap limits the pressure pin, the end of the fixed tail cap extends into the first sliding groove. Since the length of the first sliding groove is greater than its width, when the end of the fixed tail cap extends into the first sliding groove, the end of the fixed tail cap can fully contact with tissue fluid such as blood, thereby ensuring the stable degradation of the fixed tail cap in the first sliding groove, ensuring that the pressure pin slides up and down in the first sliding groove and the second sliding groove, generating stress stimulation on the fracture position, promoting fracture healing, and shortening fracture healing time.

[0010] Preferably, the fixed tail cap is absorbed in the human body for 10-40 days, and the material of the fixed tail cap is selected from one or more of polylactic acid, polyglycolic acid, polycaprolactone, chitosan or fibrin. By selecting the degradable material, the fixed tail cap can be degraded within a precise time, realizing the transition from static to dynamic stage, improving the fracture healing effect and shortening the healing time.

[0011] Preferably, the front end of the load-bearing interlocking nail is smooth and has no threads, and the tail end of the load-bearing interlocking nail is fixedly connected with an expansion nail. The expansion of the tail end of the load-bearing interlocking nail is controlled by controlling the screwing amount of the expansion nail, so that the tail end forms an interference fit with the main nail.

[0012] Preferably, the expansion nail includes a connecting portion and a force-applying portion, the connecting portion is used to be connected to the load-bearing interlocking nail, for example, it can be connected by a threaded connection to achieve the adjustment of the feed amount of the expansion nail; the force-applying portion has a conical or approximately conical shape, the tail end of the load-bearing interlocking nail is provided with a conical hole that cooperates with the force-applying portion, and the conical hole is provided with a plurality of notches, and the deformation of the hole wall of the conical hole is increased by adjusting the feed amount of the expansion nail, so that the tail end and the main nail form an interference fit for fixation.

[0013] The present application also relates to an installation method of a load-bearing intramedullary nail system with a pressurizing function, the installation method comprising S1. using a drill bit to drill a main nail hole on a second fixed object, and installing the main nail; S2. drilling a mounting hole for the load-bearing interlocking nail along the locking hole on the second fixed object, and installing the load-bearing interlocking nail in the mounting hole, so that the load-bearing interlocking nail and the main nail form an interference fit; S3. drilling a mounting hole for the pressurizing nail on the second fixed object such as a femoral body, a cervical bone, etc. along the bottom contour of the first sliding groove, and installing the pressurizing nail, for example When the first sliding groove is a rectangular or oblong waist-shaped hole, the projection of the mounting hole is inscribed inwardly with the bottom contour of the first sliding groove, so that the bottom contour of the first sliding groove can be used to limit the bottom of the pressure pin; S4. Tighten the pressure pin and install the fixed tail cap to limit the pressure pin. Since the front end of the pressure pin is connected to the bone block by a thread, the tail end of the pressure pin is limited by the fixed tail cap and the first sliding groove, so that the first fixed object such as the bone block and the femoral head is tightly connected to the second fixed object such as the femoral body, thereby realizing static fixation of fracture healing.

[0014] Preferably, in step S2, alignment marks are provided on the load-bearing interlocking nail and the main nail, and when installing the load-bearing interlocking nail, the alignment marks are aligned to ensure the correct installation direction of the second sliding groove of the load-bearing interlocking nail.

[0015] Preferably, in step S3, the mounting hole of the pressure pin is drilled at least twice. First, the mounting hole of the pressure pin is drilled on the second fixed object along the bottom contour of the first sliding groove by a drill bit. The diameter of the mounting hole is adapted to the diameter of the pressure pin, so as to facilitate the processing of internal threads in the first fixed object. Then, the non-internal threaded section of the mounting hole is further expanded to increase the cross-sectional size of the non-internal threaded section, so that the pressure pin can be slightly moved in the mounting hole of the non-internal threaded section after losing its limiting effect, thereby ensuring stress stimulation in the later stage of healing.

[0016] The present invention aims to provide a load-bearing intramedullary nail system with a pressurization function and an installation method thereof. The pressurization nail is limited by a fixed tail cap to achieve fixation of the pressurization nail, thereby realizing the pressurization function of the fixed object immediately after the operation is completed. The cooperation between the interlocking nail and the main nail is a mechanical locking structure, and the pressurization nail with the ability to accurately adjust the pressurization amount is combined. During early healing, no micro-movement occurs between the interlocking nail and the main nail, thereby no bone block sliding, thereby forming an absolutely stable fixation, and achieving static healing in the early stage of fracture healing. By selecting the fixed tail cap to be made of a degradable material, the fixed tail cap degrades itself within a certain period of time and is absorbed by the human body, thereby causing the pressurization nail to lose its limit, and the pressurization nail slides up and down in the first sliding groove and the second sliding groove, and the bone block can make limited micro-movements, thereby generating stress stimulation on the fracture position, promoting fracture healing, and shortening the fracture healing time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of the load-bearing intramedullary nail system of the present application; Figure 2 This is a schematic diagram of the limiting structure of the pressure nail in this application; Figure 3 This is a schematic diagram of the installation structure of the compression nail and the load-bearing interlocking nail of this application; Figure 4 This is a schematic diagram of the installation structure of the expansion nails in this application; Figure 5 Schematic diagram of drilling the main nail mounting holes for this application; Figure 6 Schematic diagram of drilling the load-bearing interlocking nail mounting holes for this application.

[0018] Description of reference numerals: 1-main nail, 11-first sliding groove, 12-locking hole, 13-fixing hole, 14-fixing tail cap, 2-pressure nail, 3-load-bearing interlocking nail, 31-second sliding groove, 32-expansion nail, 33-conical hole. DETAILED DESCRIPTION

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] In order to simplify the drawings, only the parts related to the present invention are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0021] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0022] In this document, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] In order to overcome the shortcomings of the intramedullary nail internal fixation technology in the prior art, the present invention proposes a load-bearing intramedullary nail system with a pressurization function, the load-bearing intramedullary nail system comprising a main nail 1, a pressurization nail 2 and a load-bearing interlocking nail 3, the main nail 1 is provided with a first sliding groove 11 and a locking hole 12, the length of the first sliding groove 11 is greater than its width, see Figure 1 As shown in, a fixing hole 13 is provided at one end of the main nail 1 adjacent to the first sliding groove 11, the load-bearing interlocking nail 3 has a second sliding groove 31, the length of the second sliding groove 31 is greater than its width, and a threaded structure is provided at the end of the pressure nail 2 for connecting with a first fixed object such as a femoral head, a femoral block, etc. The load-bearing interlocking nail 3 is passed through the locking hole 12 of the main nail 1 and connected with the first fixed object, and the pressure nail 2 passes through the first sliding groove 11 of the main nail 1 and the second sliding groove 31 of the load-bearing interlocking nail 3 in sequence and is fixedly connected with the first fixed object, and the main nail 1 is fixedly installed on the second fixed object such as a femoral body, a femoral neck, etc.; it also has a fixed tail cap 14, and the fixed tail cap 14 limits the pressure nail 2 through the fixing hole 13, and the fixed tail cap 14 is made of degradable material. The load-bearing intramedullary nail system of the present invention limits the pressure nail 2 through the fixed tail cap 14 as shown in FIG. Figure 2As shown in the figure, the fixation of the pressure nail 2 is realized, so that the pressure function of the first fixed object is realized immediately after the operation is completed. The cooperation between the interlocking nail and the main nail 1 is a mechanical locking structure, and the pressure nail 2 that can accurately adjust the pressure amount is combined. During the early healing, there will be no micro-movement between the interlocking nail and the main nail 1, and thus the first fixed object will not be caused to slide, forming an absolutely strong internal fixation, and realizing static healing in the early stage of fracture healing; when the fixed tail cap 14 is selected to be made of a degradable material, the fixed tail cap 14 degrades itself within a certain period of time and is absorbed by the human body, so that the pressure nail 2 loses its limit, and the pressure nail 2 slides up and down in the first sliding groove 11 and the second sliding groove 31, and the bone block can make limited micro-movements, which produces stress stimulation on the fracture position, promotes fracture healing, and shortens the fracture healing time.

[0024] Preferably, the bottom profile of the second sliding groove 31 is lower than the bottom profile of the first sliding groove 11, so that the second sliding groove 31 has no limiting effect on the pressure pin 2. Figure 3 As shown in the figure, when the compression nail 2 loses its limiting effect, the first fixing object can slightly move along the axis of the load-bearing interlocking nail 3, thereby preventing the first fixing object from healing in a dislocated manner and promoting the healing of the fracture.

[0025] Preferably, the fixed tail cap 14 applies pressure to the pressurized nail 2 through a threaded structure to limit the position, the fixing hole 13 is provided with a thread, and the fixed tail cap 14 is provided with an external thread, and the pressurized nail 2 is limited by screwing the fixed tail cap 14 into the fixing hole 13.

[0026] Preferably, the fixing hole 13 is a through hole, the end of the main nail 1 is provided with an external thread, and the fixed tail cap 14 includes a nut and a limiting rod located at the center of the nut, and the limiting rod limits the pressure nail 2 by cooperating with the external thread at the end of the main nail 1.

[0027] Preferably, when the fixed tail cap 14 limits the pressure pin 2, the end of the fixed tail cap 14 extends into the first sliding groove 11. Since the length of the first sliding groove 11 is greater than its width, when the end of the fixed tail cap 14 extends into the first sliding groove 11, the end of the fixed tail cap 14 can fully contact with tissue fluid such as blood, thereby ensuring the stable degradation of the fixed tail cap 14 in the first sliding groove 11, ensuring that the pressure pin 2 slides up and down in the first sliding groove 11 and the second sliding groove 31, generating stress stimulation on the fracture position, promoting fracture healing, and shortening fracture healing time.

[0028] Preferably, the fixed tail cap 14 is absorbed in the human body for 10-40 days, and the material of the fixed tail cap 14 is selected from one or more of polylactic acid, polyglycolic acid, polycaprolactone, chitosan or fibrin. By selecting the degradable material, the fixed tail cap 14 can be degraded within a precise time, realizing the transition from static to dynamic stage, improving the fracture healing effect and shortening the healing time.

[0029] Preferably, the front end of the load-bearing interlocking nail 3 is smooth and has no threads, and the tail end of the load-bearing interlocking nail 3 is fixedly connected with an expansion nail 32. The expansion of the tail end of the load-bearing interlocking nail 3 is controlled by controlling the screwing amount of the expansion nail 32, so that the tail end forms an interference fit with the main nail 1.

[0030] Preferably, Figure 4 As shown in the figure, the expansion nail 32 includes a connecting portion and a force-applying portion, the connecting portion is used to be connected to the load-bearing interlocking nail 3, for example, it can be connected by a threaded connection to achieve the adjustment of the feed amount of the expansion nail 32; the force-applying portion has a conical or approximately conical shape, and the tail end of the load-bearing interlocking nail 3 is provided with a conical hole that cooperates with the force-applying portion, and the conical hole is provided with a plurality of notches. By adjusting the feed amount of the expansion nail 32, the deformation of the hole wall of the conical hole is increased, and the tail end is fixed by forming an interference fit with the main nail 1.

[0031] The present application also relates to an installation method of a load-bearing intramedullary nail system with a pressurizing function, the installation method comprising S1. using a drill bit to drill an installation hole for a main nail 1 on a second fixed object, and installing the main nail 1, such as Figure 5 As shown in; S2. Drill the mounting hole of the load-bearing interlocking nail 3 along the locking hole 12 on the second fixed object, such as Figure 6 As shown in, and the load-bearing interlocking nail 3 is installed in the mounting hole, and the load-bearing interlocking nail 3 is formed with the main nail 1 as an interference fit; S3. The mounting hole of the pressure nail 2 is drilled on the second fixed object such as the femoral body, cervical bone, etc. along the bottom contour of the first sliding groove 11, and the pressure nail 2 is installed. For example, when the first sliding groove 11 is a rectangular or oblong waist-shaped hole, the projection of the mounting hole is inscribed with the bottom contour of the first sliding groove 11, so that the bottom contour of the first sliding groove 11 can be used to limit the bottom of the pressure nail 2; S4. Tighten the pressure nail 2, install the fixed tail cap 14 to limit the pressure nail 2, because the front end of the pressure nail 2 is connected to the bone block by a thread, and the tail end of the pressure nail 2 is limited by the fixed tail cap 14 and the first sliding groove 11, so that the first fixed object such as the bone block and the femoral head is tightly connected to the connected second fixed object such as the femoral body, thereby realizing static fixation of fracture healing.

[0032] Preferably, in step S2, alignment marks are provided on the load-bearing interlocking nail 3 and the main nail 1. When installing the load-bearing interlocking nail 3, the alignment marks are aligned to ensure the correct installation direction of the second sliding groove 31 of the load-bearing interlocking nail 3.

[0033] Preferably, in step S3, the mounting hole of the pressure pin 2 is drilled at least twice. First, the mounting hole of the pressure pin 2 is drilled on the second fixed object along the bottom contour of the first sliding groove by a drill bit. The diameter of the mounting hole is adapted to the diameter of the pressure pin 2 to facilitate processing of internal threads in the first fixed object. Then, the non-internal threaded section of the mounting hole is further expanded to increase the size of the non-internal threaded section, so that the pressure pin 2 can be slightly moved in the mounting hole of the non-internal threaded section after losing its limiting effect.

Claims

1. A load-bearing intramedullary nail system with a pressurizing function, comprising a main nail, a pressurizing nail and a load-bearing interlocking nail, characterized in that; The main nail is provided with a first sliding groove and a locking hole, the length of the first sliding groove is greater than its width, a fixing hole is provided at one end of the main nail adjacent to the first sliding groove, the load-bearing interlocking nail has a second sliding groove, the length of the second sliding groove is greater than its width, a threaded structure is provided at the end of the pressure nail for connecting with the first fixed object, the load-bearing interlocking nail is passed through the locking hole of the main nail and connected with the first fixed object, the pressure nail passes through the first sliding groove of the main nail and the second sliding groove of the load-bearing interlocking nail in sequence and is fixedly connected to the first fixed object, and the main nail is fixedly installed on the second fixed object; it also has a fixed tail cap, the fixed tail cap limits the pressure nail through the fixing hole, and the tail cap is made of degradable material.

2. The loadable intramedullary nail system according to claim 1, characterized in that: The bottom contour of the second sliding groove is lower than the bottom contour of the first sliding groove, so that the second sliding groove has no limiting effect on the pressure pin.

3. The loadable intramedullary nail system according to claim 1 or 2, characterized in that: The fixed tail cap applies pressure to the pressurized nail through a threaded structure to limit the position. The fixing hole is provided with a thread, and the fixed tail cap is provided with an external thread. The pressurized nail is limited by screwing the fixed tail cap into the fixing hole.

4. The loadable intramedullary nail system according to claim 1 or 2, characterized in that: When the fixed tail cap limits the pressure pin, the end of the fixed tail cap extends into the first sliding groove.

5. The loadable intramedullary nail system according to claim 1 or 2, characterized in that: The material for fixing the tail cap is selected from one or more of polylactic acid, polyglycolic acid, polycaprolactone, chitosan or fibrin.

6. The loadable intramedullary nail system according to claim 1 or 2, characterized in that: The front end of the load-bearing interlocking nail is smooth and has no threads, and the rear end of the load-bearing interlocking nail is fixedly connected with an expansion nail.

7. The loadable intramedullary nail system according to claim 6, characterized in that: The expansion nail comprises a connecting portion and a force-applying portion, wherein the connecting portion is used to be connected to the load-bearing interlocking nail; and the force-applying portion has a conical shape.

8. A method for installing a load-bearing intramedullary nail system with a pressurizing function according to any one of claims 1 to 7, characterized in that; The installation method comprises S1. using a drill bit to drill a main nail hole on a second fixed object, and installing the main nail; S2. drilling a mounting hole for the load-bearing interlocking nail along the locking hole on the second fixed object, and installing the load-bearing interlocking nail in the mounting hole, so that the load-bearing interlocking nail and the main nail form an interference fit; S3. drilling a mounting hole for the pressure nail on the second fixed object along the bottom contour of the first sliding groove, and installing the pressure nail; S4. Tighten the pressure pin and install a fixed tail cap to limit the pressure pin.

9. The installation method according to claim 8, characterized in that: In step S2, alignment marks are provided on the load-bearing interlocking nail and the main nail. When installing the load-bearing interlocking nail, the alignment marks are aligned to ensure the correct installation direction of the second sliding groove of the load-bearing interlocking nail.

10. The installation method according to claim 8 or 9, characterized in that: In step S3, the mounting hole of the pressure pin is drilled at least twice. First, the mounting hole of the pressure pin is drilled on the second fixed object along the bottom contour of the first sliding groove by a drill bit. The diameter of the mounting hole is adapted to the diameter of the pressure pin to facilitate the processing of internal threads in the first fixed object. Then, the non-internal thread section of the mounting hole is further expanded to increase the cross-sectional size of the non-internal thread section.

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