A fixing device

Abstract

The present invention provides a fixing device comprising an anti-backout screw and a limiting hole. The anti-backout screw is provided with a first limiting tooth, and the limiting hole is provided with a second limiting tooth. The first limiting tooth and the second limiting tooth have different pitches and / or the bottom diameter of the second limiting tooth gradually decreases. When the anti-backout screw engages with the limiting hole, the first limiting tooth cuts and deforms the second limiting tooth, forming an anti-backout structure. The fixing device is particularly suitable for use as an internal fixation device, with a simple structure and easy operation. By controlling the pitch and bottom diameter of the first and second limiting teeth, the risk of screw backout can be reduced while ensuring the function. The anti-backout structure is applicable not only to ordinary screws but also to hollow compression screws.

Description

Technical Field

[0001] The present invention belongs to the technical field of orthopedic medical devices, and in particular relates to a fixing device. Background Art

[0002] Fractures are a common type of injury in orthopedic medicine. They are categorized into two main types: articular surface fractures and periarticular fractures, with long tubular fractures being the most common type. In orthopedic practice, plate fixation is one of the most common and effective treatments for long tubular fractures.

[0003] When a bone structure is completely or partially broken, prompt treatment is needed to allow the fracture to heal. This is typically achieved through the use of screws and plates to reinforce the fracture. Plates provide strong fixation, accelerate healing, and prevent sequelae. For more severe fractures, plates are used to apply pressure to the fractured bone structure to ensure proper healing.

[0004] Currently, existing headless compression screws, non-locking cannulated screws, and locking cannulated screws, when used alone to fix fractures, can lead to loss of reduction, screw backout, and easy rotation of the fracture fragment. Non-locking cannulated screws, when used in conjunction with a plate, can compress the fracture fragment, but the screw cannot lock with the plate, making it prone to backout and loss of reduction. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a fixing device, which has a simple structure, is easy to use, and can reduce the risk of screw backing out.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A fixing device includes an anti-retraction screw and a limiting hole.

[0008] The anti-retraction screw includes a nail cap and a nail rod;

[0009] The nail cap has a first limiting tooth on its upper portion, wherein the first limiting tooth is a thread segment circumferentially arranged around the outer surface of the upper portion of the nail cap;

[0010] The nail rod has one end connected to the nail cap and a first thread provided on its surface;

[0011] The limiting hole comprises a through hole having a first end, a second end, and an inner surface extending between the first end and the second end;

[0012] The inner surface of the through hole is provided with a second limiting tooth, a micro-motion groove and a receiving groove in sequence from the first end to the second end;

[0013] The second limiting teeth are thread segments circumferentially arranged around the inner surface of the through hole;

[0014] The micro-motion groove is used to receive the first limiting tooth;

[0015] The receiving groove is used to receive the lower part of the nail cap and is adapted to the lower part of the nail cap;

[0016] The first limiting tooth and the second limiting tooth have different pitches and / or the bottom diameter of the second limiting tooth gradually decreases from the first end to the second end; after the first limiting tooth cuts the second limiting tooth, it is located in the micro-motion groove to form an anti-retreat structure.

[0017] Furthermore, the fixing device is an internal fixing device.

[0018] Furthermore, the pitch of the first limiting tooth is constant, and the pitch of the second limiting tooth is variable.

[0019] Preferably, the number of the first limiting teeth is less than the number of the second limiting teeth.

[0020] Preferably, the number of the first limiting teeth is at least 2, and preferably the first limiting teeth are multi-line thread teeth, more preferably four-line thread teeth.

[0021] Preferably, the material hardness of the first limiting tooth is greater than the material hardness of the second limiting tooth.

[0022] Furthermore, the length of the first limiting tooth screwed into the limiting hole is 1 / 8-1 / 6 of the pitch.

[0023] Furthermore, the lower part of the nail cap is in a locking fit or a non-locking fit with the receiving groove; the lower part of the nail cap is provided with a fifth thread or no thread; the receiving groove is provided with a fourth thread that cooperates with the fifth thread or no thread.

[0024] Furthermore, the receiving groove is a ball socket groove or a tapered groove.

[0025] Furthermore, the anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in a non-locked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with a first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

[0026] Furthermore, the height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

[0027] Furthermore, a second thread is provided at the connection between the nail cap and the nail rod, a smooth section is provided between the second thread and the first limiting tooth, and the second thread has the same rotation direction as the first thread; a fixing hole is also provided between the receiving groove and the second end, and a third thread is provided in the fixing hole, the rotation direction of the third thread is opposite to the rotation direction of the second limiting tooth, and the second thread can cooperate with the third thread.

[0028] Furthermore, the pitch of the second thread is smaller than the pitch of the first thread.

[0029] Compared with the prior art, the fixing device of the present invention has the following advantages and positive effects:

[0030] 1. The fixing device provided by the present invention has a simple structure and is easy to operate. The first limiting tooth cooperates with the second limiting tooth. By controlling the pitch and / or bottom diameter, the risk of screw withdrawal can be reduced while ensuring the function. The anti-screw withdrawal mechanism can be used to prevent hollow pressurized screws or other screws from withdrawing.

[0031] 2. The fixing device provided by the present invention can perform axial compression and can also provide a relatively stable fixing method when the tension screw cooperates with the bone plate.

[0032] 3. The fixation device provided by the present invention can provide doctors with two fixation methods: absolutely stable and relatively stable. The corresponding fixation method can be selected according to the patient's fracture condition. It has high flexibility and a wide range of applications.

[0033] 4. The lag screw of the fixation device provided by the present invention can not only perform axial pressure, but also form a threaded fixation between the lag screw and the bone plate, thereby reducing pressure on the periosteum, increasing blood supply, and having a significant anti-rotation effect.

[0034] 5. The first limiting tooth of the fixing device provided by the present invention has a short length when screwed into the limiting hole, so the screw can be screwed in quickly to prevent loss of resetting. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of a fixation device for fixing a fracture position provided by an embodiment of the present invention.

[0036] Figure 2 This is a front view of an anti-retraction screw provided in one embodiment of the present invention.

[0037] Figure 3 It is a cross-sectional view of an anti-retraction screw provided in one embodiment of the present invention.

[0038] Figure 4 It is a cross-sectional view of a limiting hole provided in one embodiment of the present invention.

[0039] Figure 5 It is a top view of a limiting hole provided in one embodiment of the present invention.

[0040] Figure 6 It is a schematic diagram of the state when the anti-retraction screw and the limiting hole provided by an embodiment of the present invention are not matched.

[0041] Figure 7 It is a schematic diagram of the state when the first limiting tooth and the second limiting tooth are in contact with each other provided by an embodiment of the present invention.

[0042] Figure 8 It is a schematic diagram of the state when the first limiting tooth cuts the second limiting tooth provided by an embodiment of the present invention.

[0043] Figure 9 It is a schematic diagram of a fixing device provided by one embodiment of the present invention in a relatively stable fixing state.

[0044] Figure 10 It is a schematic diagram of a fixing device provided by one embodiment of the present invention in an absolutely stable fixing state.

[0045] In the picture:

[0046] 1. Hollow tension screw; 11. Cap; 111. First limiting tooth; 112. Second thread; 12. Rod; 121. First thread; 122. Polished rod; 13. Axial direction of the anti-retraction screw;

[0047] 2. Limiting hole; 21. Second limiting tooth; 22. Micro-motion groove; 23. Receiving groove; 24. Third thread; 25. Fixing hole; 26. First end; 27. Second end;

[0048] 3. Bone plate;

[0049] 4. Fracture fragments;

[0050] 5. Fracture. DETAILED DESCRIPTION

[0051] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0052] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0053] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0054] In order to solve the technical problem of screws retreating from holes in the prior art, the present invention provides a fixing device including an anti-retreat screw and a limiting hole 2 . The anti-retreat screw includes a screw cap 11 and a screw rod 12 .

[0055] The nail cap 11 has a first limiting tooth 111 on its upper portion. The first limiting tooth 111 is a thread segment circumferentially arranged around the outer surface of the upper portion of the nail cap 11.

[0056] A nail rod 12, one end of which is connected to the nail cap 11 and has a first thread 121 on its surface;

[0057] The limiting hole 2 is used to accommodate the nail cap 11 of the anti-retraction screw, including a through hole having a first end 26, a second end 27 and an inner surface extending between the first end 26 and the second end 27;

[0058] The inner surface of the through hole is provided with a second limiting tooth 21, a micro-motion groove 22 and a receiving groove 23 in sequence from the first end 26 to the second end 27;

[0059] The second limiting teeth 21 are thread segments circumferentially arranged around the inner surface of the through hole;

[0060] The micro-motion groove 22 is used to receive the first limiting tooth 111;

[0061] The receiving groove 23 is used to receive the lower part of the nail cap 11;

[0062] The first limiting tooth 111 has a different pitch from the second limiting tooth 21 and / or the bottom diameter of the second limiting tooth 21 gradually decreases from the first end 26 to the second end 27; after the first limiting tooth 111 cuts the second limiting tooth 21, it is located in the micro-motion groove 22 to form an anti-retreat structure.

[0063] In the fixing device provided by the present invention, when the anti-retraction screw is matched with the limiting hole 2, the first limiting tooth 111 set by the anti-retraction screw needs to cut the second limiting tooth 21 set in the limiting hole 2. Due to the control of the pitch and / or bottom diameter, the first limiting tooth 111 is difficult to withdraw from the second limiting tooth 21 after cutting, thereby forming an anti-retraction structure and reducing the risk of the screw withdrawing from the hole.

[0064] The fixing device is applicable to the field of machinery and the field of orthopedic medical devices, and is particularly applicable to fixing devices in the field of orthopedic medical devices. When the fixing device is a fixing device, it can be made of a biocompatible material. The anti-retraction screw can be a locking screw or a non-locking screw. The limiting hole 2 is provided on the internal fixator, and the internal fixator can be a spinal internal fixator (such as a vertebral plate), a traumatic internal fixator (such as a bone plate 3) or a joint internal fixator (such as an acetabular cup), etc. The internal fixation system can be a spinal internal fixation system (such as a vertebral plate, an anti-retraction screw and a fusion device), a traumatic internal fixation system (such as a bone plate 3 and an anti-retraction screw), or a joint internal fixation system (such as an acetabular cup and an anti-retraction screw), which includes the above-mentioned internal fixator.

[0065] Furthermore, to facilitate manufacturing, the pitch of the first limiting teeth 111 is constant, and the pitch of the second limiting teeth 21 is variable.

[0066] In order to further enhance the anti-retraction effect of the fixing device, the number of the first limiting teeth 111 is less than the number of the second limiting teeth 21. Preferably, the number of the first limiting teeth 111 is much less than the number of the second limiting teeth 21, such as the number of the first limiting teeth 111 is 3, and the number of the second limiting teeth 21 is 13; the number of the first limiting teeth 111 is 4, and the number of the second limiting teeth 21 is 20, etc.

[0067] Preferably, the number of the first limiting teeth 111 is at least 2, and preferably the first limiting teeth 111 are multi-thread teeth, more preferably four-thread teeth, to further enhance the anti-retreat effect of the fixing device.

[0068] To ensure that the first limiting tooth 111 can cut through the second limiting tooth 21 and enter the fine-motion groove 22, the material hardness of the first limiting tooth 111 is greater than that of the second limiting tooth 21. When the fixture is used for internal fixation, the first limiting tooth 111 can be made of TC20, TC4, or cobalt-chromium-molybdenum, while the second limiting tooth 21 can be made of TC20, TC4, or TA3. When the fixture is used in other fields, those skilled in the art can select the material according to their needs, as long as it ensures that the first limiting tooth 111 cuts into the second limiting tooth 21.

[0069] In order to prevent the loss of reduction during the internal fixation process, the length of the first limiting tooth 111 screwed into the limiting hole 2 is as small as possible, for example, a pitch of 1 / 8-1 / 6, such as 1 / 7 pitch, etc.

[0070] The receiving groove 23 is used to receive the lower part of the nail cap 11, and it is adapted to the lower part of the nail cap 11. It can be a ball socket groove or a conical groove, etc. For example, when the anti-backward screw is a locking screw, it can be a conical groove, and the inner surface of the conical groove is provided with a fourth thread, which cooperates with the fifth thread on the outer surface of the lower part of the nail cap 11; when the anti-backward screw is a non-locking screw, it can be a ball socket groove, and the inner surface of the ball socket groove may not be provided with a thread. At this time, the lower part of the nail cap 11 may also not be provided with a thread.

[0071] In the above fixing device, the rotation direction of the first limiting tooth 111 is the same as that of the second limiting tooth 21, the rotation direction of the first thread 121, the fourth thread and the fifth thread are the same, and the rotation direction of the first limiting tooth 111 is the same as or opposite to that of the first thread 121.

[0072] The above-mentioned fixing device can also be used to cooperate with the bone plate 3 to pressurize and fix the fracture fragment 4, that is, the anti-retraction screw can be a tension screw. In this case, the lower portion of the nail cap 11 and the receiving slot 23 are in an unlocked state, the section of the nail rod 12 close to the nail cap 11 is a smooth rod 122, and the section of the nail rod 12 away from the nail cap 11 is provided with a first thread 121. The first thread 121 and the first limiting tooth 111 have opposite rotation directions, and the first limiting tooth 111 and the second limiting tooth 21 have the same rotation direction. The tension screw can be a hollow tension screw 1 or a solid tension screw. In this case, the fixing device can not only pressurize the fracture fragment 4, but also reduce the risk of the tension screw retreating.

[0073] In order to provide relatively stable fixation for the fracture position, the height of the micro-motion groove 22 along the axial direction of the through hole is greater than the height of the first limiting tooth 111 along the axial direction 13 of the anti-retraction screw; the height of the receiving groove 23 along the axis of the through hole is greater than the height of the lower part of the nail cap 11 along the axial direction 13 of the anti-retraction screw, so as to realize micro-motion between the anti-retraction screw and the limiting hole 2 during internal fixation.

[0074] When the tension screw is engaged with the limiting hole 2, there is a certain degree of micro-motion between the tension screw and the limiting hole 2, which can exert pressure on the fracture fragment 4 and relatively fix it. However, for fractures in the joint area, absolute stability is required. In order to facilitate surgery and provide doctors with more surgical options, a second thread 112 is provided at the connection between the nail cap 11 and the nail rod 12. The second thread 112 has the same rotation direction as the first thread 121. A fixing hole 25 is also provided between the receiving groove 23 and the second end 27. The fixing hole 25 is provided with a third thread 24. The rotation direction of the third thread 24 is opposite to that of the second limiting tooth 21. The second thread 112 can threadably engage with the third thread 24. At this time, the tension screw and the bone plate 3 can provide axial pressure and two fixing modes: relative fixation and absolute fixation, which can facilitate doctors to choose the required fixing method during surgery.

[0075] In order to compensate for the loss of restoration during absolute fixation, the pitch of the second thread 112 is smaller than the pitch of the first thread 121 .

[0076] The embodiments of the present invention are further described below with reference to the accompanying drawings:

[0077] Example 1: First fixing device

[0078] The unique anti-backoff structure of the fixing device can reduce the risk of the screw backing out of the plate. The anti-backoff structure is applicable not only to locking screws but also to non-locking screws.

[0079] The first fixing device includes an anti-retraction screw and a bone plate 3 used in conjunction with the screw;

[0080] The anti-retraction screw includes a nail cap 11 and a nail rod 12;

[0081] The cap 11 has a first position-limiting tooth 111 on its upper portion. The first position-limiting tooth 111 is a threaded segment circumferentially arranged around the outer surface of the upper portion of the cap 11. The lower portion of the cap 11 can be a smooth surface or a surface provided with a fifth thread (i.e., the screw can be a locking screw or a non-locking screw).

[0082] The number of the first limiting teeth 111 is at least 2, such as 3, 4, 5 or 6, and preferably 4. The first limiting teeth 111 are preferably multi-threaded teeth, more preferably four-threaded teeth, and the plurality of first limiting teeth 111 are evenly spaced on the upper outer surface of the nail cap 11.

[0083] The outer surface of the nail rod 12 is provided with a first thread 121 .

[0084] The bone plate 3 is provided with a limiting hole 2, which includes a through hole having a first end 26, a second end 27 and an inner surface extending between the first end 26 and the second end 27;

[0085] The inner surface of the through hole is provided with a second limiting tooth 21, a micro-motion groove 22 and a receiving groove 23 in sequence from the first end 26 to the second end 27;

[0086] The second limiting tooth 21 is a thread segment circumferentially arranged around the inner surface of the through hole; the rotation direction of the second limiting tooth 21 is the same as that of the first limiting tooth 111, and can be the same as or opposite to the rotation direction of the first thread 121; the pitch of the second limiting tooth 21 is different from the pitch of the first limiting tooth 111, the pitch of the first limiting tooth 111 is constant, and the second limiting tooth 21 has a variable pitch, and / or the bottom diameter of the second limiting tooth 21 gradually decreases from the first end 26 to the second end 27; in addition, the material hardness of the second limiting tooth 21 is less than the material hardness of the first limiting tooth 111 (the first The material of the limiting teeth 111 can be TC20, TC4, or cobalt-chromium-molybdenum, and the material of the second limiting teeth 21 can be TC20, TC4, or TA3, etc.); the number of the second limiting teeth 21 is greater than the number of the first limiting teeth 111, and preferably much greater than the number of the first limiting teeth 111; the first limiting teeth 111 cut through the second limiting teeth 21 and are located in the micro-motion groove 22, forming an anti-retraction mechanism; the shorter the length of the first limiting teeth 111 screwed into the limiting hole 2, the better. In this embodiment, the length of the first limiting teeth 111 screwed into the limiting hole 2 is 1 / 8-1 / 6 of the circumference;

[0087] The fine motion groove 22 is used to receive the first limiting tooth 111; optionally, the height of the fine motion groove 22 along the axial direction of the through hole is greater than the height of the first limiting tooth 111 along the axial direction of the anti-retraction screw 13;

[0088] The receiving groove 23 is used to receive the lower part of the nail cap 11. The shape of the receiving groove 23 is adapted to the lower part of the nail cap 11. In this embodiment, the nail cap 11 is a spherical cap or a conical cap, and the receiving groove 23 is a ball socket groove or a conical groove; optionally, the height of the receiving groove 23 along the axis of the through hole is greater than the height of the lower part of the nail cap 11 along the axial direction 13 of the anti-retraction screw; the receiving groove 23 is provided with a fourth thread that cooperates with the fifth thread or no thread is provided.

[0089] The first thread 121 , the fourth thread and the fifth thread have the same thread rotation direction, and are the same as or opposite to the thread rotation direction of the first limiting tooth 111 .

[0090] The first method of using the fixing device is as follows:

[0091] Step 1: implant a plate at the fracture site;

[0092] Step 2: Screw the anti-retraction screw into the limiting hole 2 of the plate until the fracture suture 5 is closed;

[0093] Step 3: Continue to screw in the anti-backward screw or screw in the anti-backward screw in the opposite direction, so that the first limiting tooth 111 cuts the second limiting tooth 21. The first limiting tooth 111 is located in the micro-motion groove 22, and the lower part of the nail cap 11 is located in the receiving groove 23. At this time, the second limiting tooth 21 can prevent the hollow tension screw from exiting. The specific explanation is as follows:

[0094] The bottom diameter of the second limiting tooth 21 is designed to gradually change from large to small, and / or the pitch of the first limiting tooth 111 is different from the pitch of the second limiting tooth 21, and the hardness of the material of the anti-retraction screw is not less than the hardness of the material of the bone plate 3. When the anti-retraction screw is matched with the bone plate 3, the first limiting tooth 111 cuts the second limiting tooth 21. During the cutting process, the material itself will undergo elastic deformation, and the first limiting tooth 111 and the second limiting tooth 21 are both damaged. The first limiting tooth 111 and the second limiting tooth 21 interfere with each other. When the anti-retraction screw is fully screwed in, the second limiting tooth 21 can play a limiting role, reducing the risk of nail withdrawal; further, the number of the second limiting teeth 21 is far greater than the number of the first limiting teeth 111, making it difficult for the anti-retraction screw to have its trajectory of withdrawal coincide with the original cutting trajectory after the anti-retraction screw is screwed into the limiting hole 2, and the probability of nail withdrawal is further reduced; the distance the first limiting tooth 111 is screwed into the limiting hole 2 is small, which can avoid loss of reset.

[0095] The first fixing device has a simple structure and is easy to operate. The first limiting tooth 111 cooperates with the second limiting tooth 21. By controlling the pitch and / or bottom diameter, the risk of screw backing out can be reduced while ensuring the function. It can also provide a relatively stable fixing method when the screw cooperates with the bone plate 3. A threaded fixation can be formed between the screw and the bone plate 3, which reduces the pressure on the periosteum, increases blood supply, and has a significant anti-rotation effect. In addition, the length of the first limiting tooth 111 screwed into the limiting hole 2 is short, and the screw can be quickly screwed in to prevent loss of reduction.

[0096] Example 2: Second fixing device

[0097] The second fixing device not only has the anti-retraction function of the first fixing device, but also has the following advantages:

[0098] Axial pressure can be applied, and a relatively stable fixing method can be provided when the tension screw cooperates with the bone plate 3; in addition, the distance that the first limiting tooth 111 is screwed into the limiting hole 2 is small, which can avoid loss of reduction.

[0099] The second fixing device includes an anti-retraction screw and a bone plate 3 matched therewith;

[0100] The anti-retraction screw is a tension screw, comprising a screw cap 11 and a screw rod 12; the tension screw cooperates with the bone plate 3 to provide the doctor with a relatively stable fixation method;

[0101] The nail cap 11 has a first limiting tooth 111 on its upper portion. The first limiting tooth 111 is a threaded segment circumferentially arranged around the outer surface of the upper portion of the nail cap 11. The lower portion of the nail cap 11 has a smooth surface.

[0102] The number of the first limiting teeth 111 is at least 2, such as 3, 4, 5 or 6. In this embodiment, the number of the first limiting teeth 111 is 4. The first limiting teeth 111 are multi-threaded teeth, preferably four-threaded teeth. The plurality of first limiting teeth 111 are evenly spaced on the upper outer surface of the nail cap 11.

[0103] The nail rod 12 has a section close to the nail cap 11 as a polished rod 122 and a section away from the nail cap 11 as a first thread 121. One end of the polished rod 122 is connected to the nail cap 11.

[0104] The first thread 121 and the first limiting tooth 111 have opposite rotation directions.

[0105] The bone plate 3 is provided with a limiting hole 2, which includes a through hole having a first end 26, a second end 27 and an inner surface extending between the first end 26 and the second end 27;

[0106] The inner surface of the through hole is provided with a second limiting tooth 21, a micro-motion groove 22 and a receiving groove 23 in sequence from the first end 26 to the second end 27;

[0107] The second limiting tooth 21 is a thread segment arranged circumferentially around the inner surface of the through hole; the rotation direction of the second limiting tooth 21 is the same as that of the first limiting tooth 111, and is opposite to the rotation direction of the first thread 121; the number of the second limiting teeth 21 is greater than the number of the first limiting teeth 111, and preferably the number of the second limiting teeth 21 is much greater than the number of the first limiting teeth 111; the pitch of the second limiting tooth 21 is different from the pitch of the first limiting tooth 111, the pitch of the first limiting tooth 111 is constant, the second limiting tooth 21 has a variable pitch, and the second limiting tooth 21 is arranged along the first end 26 to the second end 27; in addition, the hardness of the material of the second limiting tooth 21 is less than the hardness of the material of the first limiting tooth 111 (the material of the first limiting tooth 111 can be TC20, TC4 or cobalt-chromium-molybdenum, etc., and the material of the second limiting tooth 21 can be TC20, TC4 or TA3, etc.); the first limiting tooth 111 cuts the second limiting tooth 21 and is located in the micro-motion groove 22 to form an anti-retraction mechanism; the shorter the length of the first limiting tooth 111 screwed into the limiting hole 2, the better. In this embodiment, the length of the first limiting tooth 111 screwed into the limiting hole 2 is 1 / 8-1 / 6 of the circumference;

[0108] The fine motion groove 22 is used to receive the first limiting tooth 111; the height of the fine motion groove 22 along the axial direction of the through hole is greater than the height of the first limiting tooth 111 along the axial direction of the anti-retraction screw 13;

[0109] The receiving groove 23 is used to receive the lower part of the nail cap 11; the receiving groove 23 cooperates with the lower part of the nail cap 11, preferably the nail cap 11 is a spherical cap, and the receiving groove 23 is a ball socket groove; the height of the receiving groove 23 along the axis of the through hole is greater than the height of the lower part of the nail cap 11 along the axial direction 13 of the anti-retraction screw; no thread is set in the receiving groove 23.

[0110] The second fixing device is used as follows:

[0111] Step 1: implanting a bone plate 3 at the fracture site;

[0112] Step 2: Screw the tension screw into the limiting hole 2 of the bone plate 3. Since the first limiting tooth 111 and the second limiting tooth 21 have the same rotation direction and are opposite to the rotation direction of the first thread 121 (generally, the first thread 121 is a right-handed thread and the second thread 112 is a left-handed thread), the first limiting tooth 111 and the second limiting tooth 21 only contact and do not cut. The second limiting tooth 21 can play a supporting role. At this time, the tension screw fully pressurizes the fracture fragment 4 until the fracture suture 5 is closed.

[0113] Step 3: Reverse the tension screw. The first limiting tooth 111 cuts the second limiting tooth 21. The first limiting tooth 111 is located in the micro-motion groove 22. The lower part of the nail cap 11 is located in the receiving groove 23. At this time, the second limiting tooth 21 can prevent the tension screw from exiting. The specific explanation is as follows:

[0114] Since the second limiting tooth 21 in the limiting hole 2 of the bone plate 3 has the same rotation direction as the first limiting tooth 111 and the opposite rotation direction to the first thread 121, the tension screw needs to be reversed so that the first limiting tooth 111 can cut the second limiting tooth 21; the bottom diameter of the second limiting tooth 21 is gradually changed from large to small, and / or the pitch of the first limiting tooth 111 is different from the pitch of the second limiting tooth 21, and the hardness of the tension screw material is not less than the hardness of the bone plate 3 material. When the tension screw is matched with the bone plate 3, the first limiting tooth 111 cuts the second limiting tooth 21, and the material is not cut off during the cutting process. The first limiting tooth 111 and the second limiting tooth 21 will be elastically deformed, and both the first limiting tooth 111 and the second limiting tooth 21 will be damaged. The first limiting tooth 111 and the second limiting tooth 21 will interfere with each other. When the tension screw is fully screwed in, the second limiting tooth 21 can play a limiting role, reducing the risk of nail withdrawal. Furthermore, the number of the second limiting teeth 21 is much greater than that of the first limiting teeth 111, so that after the tension screw is screwed into the limiting hole 2, the nail withdrawal trajectory is difficult to coincide with the original entry trajectory, and the probability of nail withdrawal is further reduced. The distance that the first limiting tooth 111 is screwed into the limiting hole 2 is small, which can avoid loss of reset.

[0115] Step 4: The lag screw can slide in the micro-motion groove 22 to achieve a relatively stable effect. A small amount of micro-motion can promote callus formation.

[0116] Due to the reverse screwing, a fracture gap exists after the screw cap 11 of the hollow tension screw sinks into the micro-motion groove 22. This fracture gap is a micro-motion gap, which realizes relative fixation of the fracture.

[0117] The second fixing device has a simple structure and is easy to operate. The first limiting tooth 111 cooperates with the second limiting tooth 21. By controlling the pitch and / or bottom diameter, the risk of screw backing out can be reduced while ensuring the function. Axial pressure can be applied, and a relatively stable fixing method can be provided when the tension screw cooperates with the bone plate 3. A threaded fixation can be formed between the tension screw and the bone plate 3, which reduces the pressure on the periosteum, increases blood supply, and has a significant anti-rotation effect. The length of the first limiting tooth 111 screwed into the limiting hole 2 is short, and the screw can be quickly screwed in to prevent loss of reduction.

[0118] The third fixing device not only has the anti-retraction function of the first fixing device, but also has the following advantages:

[0119] This third fixing device can provide doctors with two fixing methods of the tension screw and the bone plate 3: absolute stability and relative stability. Doctors can choose the corresponding fixing method according to the fracture situation. The hollow tension screw can not only perform axial pressure, but also form a threaded fixation between the hollow tension screw and the bone plate 3, reducing the pressure on the periosteum, increasing blood supply, and having a significant anti-rotation effect. In addition, the distance that the first limiting tooth 111 is screwed into the limiting hole 2 is small, which can avoid loss of reduction.

[0120] The third type of fixing device is Figures 1 to 10 As shown, it includes an anti-retraction screw and a bone plate 3 that cooperates with it:

[0121] The anti-retraction screw is a hollow tension screw, comprising a screw cap 11 and a screw rod 12;

[0122] The nail cap 11 has a first limiting tooth 111 on its upper portion. The first limiting tooth 111 is a threaded segment circumferentially arranged around the outer surface of the upper portion of the nail cap 11. The lower portion of the nail cap 11 is a ball head with a smooth surface.

[0123] The number of the first limiting teeth 111 is at least 2, such as 3, 4, 5 or 6. In this embodiment, the number of the first limiting teeth 111 is 4. The first limiting teeth 111 are multi-threaded teeth, preferably four-threaded teeth. The plurality of first limiting teeth 111 are evenly spaced on the upper outer surface of the nail cap 11.

[0124] The nail rod 12 has a section close to the nail cap 11 as a polished rod 122 and a section away from the nail cap 11 as a first thread 121. One end of the polished rod 122 is connected to the nail cap 11.

[0125] A second thread 112 is provided at the connection between the nail cap 11 and the polished rod 122. The second thread 112 has the same rotation direction as the first thread 121. The pitch of the second thread 112 is smaller than the pitch of the first thread 121. The second thread 112 is preferably provided with 3 turns.

[0126] The first thread 121 and the first limiting tooth 111 have the same rotation direction.

[0127] The bone plate 3 is provided with a limiting hole 2, which includes a through hole having a first end 26, a second end 27 and an inner surface extending between the first end 26 and the second end 27;

[0128] The inner surface of the through hole is provided with a second limiting tooth 21, a micro-motion groove 22, a receiving groove 23 and a fixing hole 25 in sequence from the first end 26 to the second end 27;

[0129] The second limiting teeth 21 are thread segments arranged circumferentially around the inner surface of the through hole; the rotation direction of the second limiting teeth 21 is the same as that of the first limiting teeth 111, and is opposite to the rotation direction of the first thread 121; the number of the second limiting teeth 21 is greater than the number of the first limiting teeth 111, and preferably the number of the second limiting teeth 21 is much greater than the number of the first limiting teeth 111; the pitch of the second limiting teeth 21 is different from the pitch of the first limiting teeth 111, the pitch of the first limiting teeth 111 is constant, and the second limiting teeth 21 have a variable pitch, and the second limiting teeth 21 are arranged along the first end 26 to the second end 2 7; in addition, the hardness of the material of the second limiting tooth 21 is less than the hardness of the material of the first limiting tooth 111 (the material of the first limiting tooth 111 can be TC20, TC4 or cobalt-chromium-molybdenum, etc., and the material of the second limiting tooth 21 can be TC20, TC4 or TA3, etc.); the first limiting tooth 111 is located in the micro-motion groove 22 after cutting the second limiting tooth 21, forming an anti-retraction mechanism; the shorter the length of the first limiting tooth 111 screwed into the limiting hole 2, the better. In this embodiment, the length of the first limiting tooth 111 screwed into the limiting hole 2 is 1 / 8-1 / 6 of the circumference;

[0130] The fine motion groove 22 is used to receive the first limiting tooth 111; the height of the fine motion groove 22 along the axial direction of the through hole is greater than the height of the first limiting tooth 111 along the axial direction of the anti-retraction screw 13;

[0131] The receiving groove 23 is used to receive the lower portion of the nail cap 11 and is adapted to the lower portion of the nail cap 11. In this embodiment, the nail cap 11 is a spherical cap and the receiving groove 23 is a spherical socket. The height of the receiving groove 23 along the axis of the through hole is greater than the height of the lower portion of the nail cap 11 along the axial direction 13 of the anti-retraction screw. No threads are provided in the receiving groove 23.

[0132] A third thread 24 matching the second thread 112 is provided in the fixing hole 25 . The pitch of the third thread 24 is smaller than the pitch of the first thread 121 .

[0133] The third method of using the fixing device is as follows:

[0134] Step 1: implanting a bone plate 3 at the fracture site;

[0135] Step 2: Screw the hollow lag screw into the limiting hole 2 of the bone plate 3. Since the first limiting teeth 111 and the second limiting teeth 21 rotate in opposite directions, the first limiting teeth 111 and the second limiting teeth 21 only contact and do not cut. The second limiting teeth 21 can play a supporting role. At this time, the hollow lag screw fully pressurizes the fracture fragment 4 until the fracture suture 5 is closed.

[0136] Step 3: Reverse the hollow lag screw and screw it into the limiting hole 2, so that the first limiting tooth 111 is located in the micro-motion groove 22 and the lower part of the nail cap 11 is located in the receiving groove 23. At this time, the second limiting tooth 21 can prevent the hollow lag screw from exiting;

[0137] Since the second limiting tooth 21 in the limiting hole 2 of the bone plate 3 has the same rotation direction as the first limiting tooth 111 and is opposite to the rotation direction of the first thread 121, the hollow tension screw is reversed and screwed into the limiting hole 2; the bottom diameter of the second limiting tooth 21 is gradually changed from large to small, and / or the pitch of the first limiting tooth 111 is different from the pitch of the second limiting tooth 21, and the hardness of the material of the hollow tension screw is not less than the hardness of the material of the bone plate 3. When the hollow tension screw is matched with the bone plate 3, the first limiting tooth 111 cuts the second limiting tooth 21, and the material itself will appear during the cutting process. Due to elastic deformation, both the first limiting tooth 111 and the second limiting tooth 21 are destroyed, and the first limiting tooth 111 interferes with the second limiting tooth 21. After the hollow tension screw is fully screwed in, the second limiting tooth 21 can play a limiting role, reducing the risk of nail withdrawal; further, the number of the second limiting teeth 21 is much greater than the number of the first limiting teeth 111, so that after the hollow tension screw is screwed into the limiting hole 2, the nail withdrawal trajectory is difficult to coincide with the original entry trajectory, and the probability of nail withdrawal is further reduced; the distance that the first limiting tooth 111 is screwed into the limiting hole 2 is small, which can avoid loss of reset;

[0138] Step 4: The hollow lag screw can slide in the micro-motion groove 22 to achieve a relatively stable effect. A small amount of micro-motion can promote callus formation.

[0139] Due to the reverse screwing, a fracture gap exists after the screw cap 11 of the hollow tension screw sinks into the micro-motion groove 22. This fracture gap is a micro-motion gap, which realizes relative fixation of the fracture.

[0140] Step 5: optionally perform absolute locking;

[0141] The operator can choose an absolute locking mode. For example, when a joint fracture requires absolute stabilization, the operator can continuously screw in the hollow tension screw in the forward direction. Since the pitch of the second thread 112 is smaller than the pitch of the first thread 121, the fracture fragment 4 is pressurized again to achieve absolute stabilization.

[0142] The third fixing device has a simple structure and is easy to operate. The first limiting tooth 111 cooperates with the second limiting tooth 21 to control the pitch and / or bottom diameter, thereby reducing the risk of screw backing out while ensuring the function. It can provide doctors with two fixing methods, namely, absolutely stable and relatively stable, and the corresponding fixing method can be selected according to the patient's fracture condition. It has high flexibility and a wide range of applications. It can also form a threaded fixation between the tension screw and the bone plate 3, thereby reducing the pressure on the periosteum, increasing blood supply, and having a significant anti-rotation effect. In addition, the length of the first limiting tooth 111 screwed into the limiting hole 2 is short, and the screw can be quickly screwed in to prevent loss of reduction.

[0143] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A fixing device, characterized in that: Including anti-retraction screws and limiting holes, The anti-retraction screw includes a nail cap and a nail rod; The nail cap has a first limiting tooth on its upper portion, wherein the first limiting tooth is a thread segment circumferentially arranged around the outer surface of the upper portion of the nail cap; The nail rod has one end connected to the nail cap and a first thread provided on its surface; The limiting hole comprises a through hole having a first end, a second end, and an inner surface extending between the first end and the second end; The inner surface of the through hole is provided with a second limiting tooth, a micro-motion groove and a receiving groove in sequence from the first end to the second end; The second limiting teeth are thread segments circumferentially arranged around the inner surface of the through hole; The micro-motion groove is used to receive the first limiting tooth; The receiving groove is used to receive the lower part of the nail cap and is adapted to the lower part of the nail cap; The first limiting tooth and the second limiting tooth have different pitches and / or the bottom diameter of the second limiting tooth gradually decreases from the first end to the second end; the first limiting tooth cuts the second limiting tooth and is located in the micro-motion groove to form an anti-retraction structure; A second thread is provided at the connection between the nail cap and the nail rod, a smooth section is provided between the second thread and the first limiting tooth, and the second thread has the same rotation direction as the first thread; A fixing hole is further provided between the receiving groove and the second end, and a third thread is provided in the fixing hole. The rotation direction of the third thread is opposite to that of the second limiting tooth, and the second thread can be threadably matched with the third thread.

2. The fixing device according to claim 1, characterized in that: The fixing device is an internal fixing device.

3. The fixing device according to claim 1 or 2, characterized in that: The pitch of the first limiting tooth is constant, and the pitch of the second limiting tooth is variable; The number of the first limiting teeth is less than the number of the second limiting teeth; The number of the first limiting teeth is at least 2, and the first limiting teeth are multi-thread teeth; The material hardness of the first limiting tooth is greater than the material hardness of the second limiting tooth.

4. The fixing device according to claim 1 or 2, characterized in that: The length of the first limiting tooth screwed into the limiting hole is 1 / 8-1 / 6 of the pitch.

5. The fixing device according to claim 3, characterized in that: The length of the first limiting tooth screwed into the limiting hole is 1 / 8-1 / 6 of the pitch.

6. The fixing device according to claim 1 or 2, characterized in that: The lower part of the nail cap is in a locking fit or a non-locking fit with the receiving groove; the lower part of the nail cap is provided with a fifth thread or no thread; the receiving groove is provided with a fourth thread that cooperates with the fifth thread or no thread.

7. The fixing device according to claim 3, characterized in that: The lower part of the nail cap is in a locking fit or a non-locking fit with the receiving groove; the lower part of the nail cap is provided with a fifth thread or no thread; the receiving groove is provided with a fourth thread that cooperates with the fifth thread or no thread.

8. The fixing device according to claim 4, characterized in that: The lower part of the nail cap is in a locking fit or a non-locking fit with the receiving groove; the lower part of the nail cap is provided with a fifth thread or no thread; the receiving groove is provided with a fourth thread that cooperates with the fifth thread or no thread.

9. The fixing device according to claim 5, characterized in that: The lower part of the nail cap is in a locking fit or a non-locking fit with the receiving groove; the lower part of the nail cap is provided with a fifth thread or no thread; the receiving groove is provided with a fourth thread that cooperates with the fifth thread or no thread.

10. The fixing device according to claim 1 or 2, characterized in that: The receiving groove is a ball-shaped groove or a tapered groove.

11. The fixing device according to claim 3, characterized in that: The receiving groove is a ball-shaped groove or a tapered groove.

12. The fixing device according to claim 4, characterized in that: The receiving groove is a ball-shaped groove or a tapered groove.

13. The fixing device according to claim 5, characterized in that: The receiving groove is a ball-shaped groove or a tapered groove.

14. The fixing device according to claim 6, characterized in that: The receiving groove is a ball-shaped groove or a tapered groove.

15. The fixing device according to claim 7, characterized in that: The receiving groove is a ball-shaped groove or a tapered groove.

16. The fixing device according to claim 8, characterized in that: The receiving groove is a ball-shaped groove or a tapered groove.

17. The fixing device according to claim 9, characterized in that: The receiving groove is a ball-shaped groove or a tapered groove.

18. The fixing device according to claim 1 or 2, characterized in that: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

19. The fixing device according to claim 3, characterized in that: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

20. The fixing device according to claim 4, characterized in that: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

21. The fixing device according to claim 5, characterized in that: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

22. The fixing device according to claim 6, characterized in that: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

23. The fixing device according to claim 7, characterized in that: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

24. The fixing device according to claim 8, characterized in that: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

25. The fixing device according to claim 9, characterized in that: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

26. The fixing device according to claim 10, characterized in that: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

27. The fixing device according to claim 11, characterized in that: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

28. The fixing device according to claim 12, wherein: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

29. The fixing device according to claim 13, wherein: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

30. The fixing device according to claim 14, wherein: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

31. The fixing device according to claim 15, characterized in that: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

32. The fixing device according to claim 16, wherein: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

33. The fixing device according to claim 17, wherein: The anti-retraction screw is a tension screw, the lower part of the nail cap and the receiving groove are in an unlocked state, a section of the nail rod close to the nail cap is a smooth rod, and a section of the nail rod away from the nail cap is provided with the first thread, the first thread and the first limiting tooth have opposite rotation directions, and the first limiting tooth and the second limiting tooth have the same rotation direction.

34. The fixing device according to claim 1 or 2, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

35. The fixing device according to claim 3, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

36. The fixing device according to claim 4, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

37. The fixing device according to claim 5, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

38. The fixing device according to claim 6, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

39. The fixing device according to claim 7, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

40. The fixing device according to claim 8, wherein: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

41. The fixing device according to claim 9, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

42. The fixing device according to claim 10, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

43. The fixing device according to claim 11, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

44. The fixing device according to claim 12, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

45. The fixing device according to claim 13, wherein: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

46. The fixing device according to claim 14, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

47. The fixing device according to claim 15, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

48. The fixing device according to claim 16, wherein: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

49. The fixing device according to claim 17, wherein: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

50. The fixing device according to claim 18, wherein: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

51. The fixing device according to claim 19, wherein: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

52. The fixing device according to claim 20, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

53. The fixing device according to claim 21, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

54. The fixing device according to claim 22, wherein: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

55. The fixing device according to claim 23, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

56. The fixing device according to claim 24, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

57. The fixing device according to claim 25, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

58. The fixing device according to claim 26, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

59. The fixing device according to claim 27, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

60. The fixing device according to claim 28, wherein: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

61. The fixing device according to claim 29, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

62. The fixing device according to claim 30, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

63. The fixing device according to claim 31, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

64. The fixing device according to claim 32, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

65. The fixing device according to claim 33, characterized in that: The height of the micro-motion groove along the axial direction of the through hole is greater than the height of the first limiting tooth along the axial direction of the anti-retraction screw; the height of the receiving groove along the axis of the through hole is greater than the height of the lower part of the nail cap along the axial direction of the anti-retraction screw.

66. The fixing device according to claim 1 or 2, characterized in that: The pitch of the second thread is smaller than the pitch of the first thread.

67. The fixing device according to claim 3, characterized in that: The pitch of the second thread is smaller than the pitch of the first thread.

68. The fixing device according to claim 4, characterized in that: The pitch of the second thread is smaller than the pitch of the first thread.

69. The fixing device according to claim 5, characterized in that: The pitch of the second thread is smaller than the pitch of the first thread.

70. The fixing device according to claim 6, characterized in that: The pitch of the second thread is smaller than the pitch of the first thread.

71. The fixing device according to any one of claims 7 to 9, characterized in that: The pitch of the second thread is smaller than the pitch of the first thread.

72. The fixing device according to claim 10, characterized in that: The pitch of the second thread is smaller than the pitch of the first thread.

73. The fixing device according to any one of claims 11 to 17, characterized in that: The pitch of the second thread is smaller than the pitch of the first thread.

74. The fixing device according to claim 18, characterized in that: The pitch of the second thread is smaller than the pitch of the first thread.

75. The fixing device according to any one of claims 19 to 33, characterized in that: The pitch of the second thread is smaller than the pitch of the first thread.

76. The fixing device according to claim 34, characterized in that: The pitch of the second thread is smaller than the pitch of the first thread.

77. The fixing device according to any one of claims 35 to 65, characterized in that: The pitch of the second thread is smaller than the pitch of the first thread.

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