Bone fracture plate fastening nail and use method thereof

Abstract

The invention discloses a bone fracture plate fastening nail and a using method thereof, and belongs to the technical field of medical instruments. The device comprises a bone fracture plate matching piece and a bone side fixing piece, a lifting unit is connected between the bone fracture plate matching piece and the bone side fixing piece, the lifting unit is in linkage with the bone fracture plate matching piece and the bone side fixing piece, and the bone fracture plate matching piece comprises a one-way locking part connected with the lifting unit and an installation part connected with the bone side fixing piece. The bone side fixing piece comprises a radial expansion part connected with the lifting unit, and the lifting unit is provided with a flexible connecting structure and a locking matching structure which are connected with the bone fracture plate matching piece and the bone side fixing piece in a matched mode. The bone fracture plate matching part and the bone side fixing part are connected into a whole through the lifting unit, fixation of the bone fracture plate and the bone is completed, expansion of the radial expansion part and attachment to the inner wall of the bone are achieved through matched connection of the flexible connecting structure of the lifting unit and the radial expansion part of the bone side fixing part, rigid contact is avoided, and connection is stable and reliable.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology, and more specifically, relates to a bone plate fastening screw and its method of use. Background Technology

[0002] In orthopedic surgery, the reliability of the fixation between the bone plate and the bone directly determines the quality of fracture healing. However, current mainstream fixation methods generally rely on threaded connections. Threaded fixation has the following limitations: during limb movement, the bone plate is prone to relative displacement with the bone, causing friction between the bone plate and screws to generate debris, which may lead to problems such as inflammation and loosening of the fixation.

[0003] Furthermore, in existing bone fixation devices, the fixation of the bone plate and the screw relies on a rigid threaded connection. The screw engages with the bone through external threads, and simultaneously engages with the fixation holes (or locking holes) of the bone plate through threads, pressing the bone plate firmly against the bone surface. However, this structure has the following inherent defects: When the human limbs move (such as joint movement and muscle contraction), the bones undergo slight deformations. Threaded connections are rigid and cannot flexibly adapt to bone deformation, leading to relative displacement between the bone plate and the bone. The fixation holes of the bone plate and the outer wall of the screw fit tightly together, and continuous friction occurs when there is relative displacement, producing metal debris (such as titanium alloy or stainless steel debris) or polymer debris. The debris generated by friction can irritate the surrounding soft tissues, potentially causing local inflammation, pain, or even a foreign body reaction. If the debris enters the medullary cavity or blood vessels, it may cause more serious systemic risks. At the same time, friction wears down the threaded structure, leading to a decrease in fixation preload, loosening of the bone plate, and ultimately affecting fracture healing.

[0004] In existing technologies, although some structures attempt to use other fastening methods, they all rely on threaded structures. These not only cannot adapt to minor deformations of the bone, but also cause continuous friction, producing titanium alloy or stainless steel debris. None of these solutions address the problem of "friction-induced debris caused by rigid connections." The debris generated by friction can easily lead to complications such as inflammation and foreign body reactions, and wear can cause the fixation to loosen. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a bone plate fastening screw and its method of use. This fastening screw is designed to structurally reduce fretting friction caused by rigid connections, thereby eliminating the source of debris, while achieving flexible and stable fixation under physiological fretting of the bone.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: The present invention first provides a bone plate fastening screw, including a bone plate fitting and a bone side fixation component, wherein a lifting unit is connected between the bone plate fitting and the bone side fixation component; The bone plate fitting is provided with an axial through hole for the lifting unit to pass through, and a one-way locking part is provided on the hole wall of the axial through hole. The skeletal fixation device is a hollow tubular structure, and the skeletal fixation device includes a radial expansion portion; The lifting unit is axially movable and passes through the inner circumference of the bone plate fitting and the bone side fixation component. The lifting unit includes a flexible connecting structure at the distal end and a locking fitting structure at the proximal end. The flexible connecting structure engages with the radial expansion part, and the locking fitting structure engages with the one-way locking part. By lifting the lifting unit proximally, the radial expansion part can be simultaneously driven to expand to anchor to the bone, and the locking fitting structure can be engaged with the one-way locking part, thereby fastening the bone plate to the bone.

[0007] The bone plate fastening screw provided by this invention offers a novel structure different from traditional threaded fixation, through its separately configured bone plate fitting component, bone-side fixation component, and lifting unit connecting the two. Firstly, this invention simplifies surgical procedures. The surgeon can first implant the fixation component into the bone, then place the fitting component on the bone plate, and finally, a single lifting action simultaneously completes bone anchoring, bone plate clamping, and system locking, improving surgical efficiency and controllability. Secondly, it establishes a flexible fixation mechanism. The radial expansion anchoring method driven by the lifting unit, along with the elastic or surface contact fit between the fitting component and the bone plate, can absorb and adapt to physiological micro-movements between the bone and the bone plate, transforming harmful friction into elastic deformation. Thirdly, it avoids the rigid friction between traditional threaded pairs, eliminating the structural basis for metal or polymer debris generation and reducing the risk of postoperative complications such as inflammation and loosening. Finally, the modular design of this invention facilitates clinical selection, allowing for flexible matching of fixation components and fitting components of different sizes or materials according to the bone quality and bone plate type of different patients.

[0008] Preferably, the bone plate fitting includes a main body, the interior of which is provided with an axial through hole, and a one-way locking part protrudes from the hole wall of the axial through hole for fitting and engaging with the locking structure of the lifting unit. The one-way locking part includes at least one wedge-type locking unit, which extends axially along the axial through hole and includes multiple protruding wedges continuously distributed axially along the axial through hole. By connecting the one-way locking part with the locking engagement structure of the lifting unit, a meshing pair is formed, achieving not only reliable one-way locking and stepless tension adjustment, but also uniform stress distribution through surface contact, avoiding fretting wear or structural fatigue caused by stress concentration, and significantly improving fatigue resistance and long-term stability.

[0009] Preferably, the number of wedge-type locking units is 1 to 6, and when the number of wedge-type locking units is greater than 1, the wedge-type locking units are evenly distributed circumferentially along the axial through hole; the protruding tops of the wedges are all located on the same plane, and the plane is perpendicular to the axis of the axial through hole; the cross-sectional shape of the wedge perpendicular to its extension direction is triangular or trapezoidal.

[0010] Preferably, the wedge includes a locking surface and a guide ramp. The locking angle α of the locking surface satisfies: 0° < α ≤ 20°; the guide angle β of the guide ramp satisfies: 20° ≤ β ≤ 40°; and β – α > 5°.

[0011] Preferably, in each wedge-type locking unit, the locking surfaces of all wedges are parallel to each other and are configured to engage simultaneously with the locking engagement structure of the lifting unit.

[0012] Preferably, the one-way locking part is connected to the main body part through an elastic beam. The axial length of the elastic beam is less than the axial length of the one-way locking part, and the one-way locking part can generate radial elastic deformation through the elastic beam.

[0013] This invention, by incorporating an elastic beam, allows the one-way locking part to undergo radial elastic deformation along most of its axial length, rather than just at the connection point. This not only ensures smooth engagement and disengagement between the wedge and the lifting unit locking mechanism but also distributes deformation stress more evenly across the axial range of the one-way locking part, effectively preventing stress concentration and improving the fatigue life and reliability of the locking mechanism.

[0014] Preferably, the main body is made of a biocompatible polymer material, and the elastic modulus of the polymer material is lower than that of the titanium alloy.

[0015] Preferably, the polymeric material includes polyetheretherketone or polyphenylene ether nitrile ketone.

[0016] Preferably, the outer side of the end of the main body is provided with a mounting surface that mates with the fixing hole of the bone plate. The mounting surface is a conical surface or a spherical curved surface. When the mounting surface is a conical surface, its taper ratio is 1:5 to 1:10.

[0017] Preferably, the assembly surface is provided with an elastic damping coating for absorbing micro-motion energy.

[0018] Preferably, the bone-side fixation member includes a sleeve body, a radial expansion portion disposed at the first end of the sleeve body, the radial expansion portion including a radial expansion structure, and the radial expansion structure being connected to the flexible connection structure of the lifting unit; The radial expansion section includes an axial groove arranged along the axial direction of the sleeve body. The length of the axial groove is less than the length of the sleeve body. The radial expansion structure is a radial expansion lobe formed by dividing the axial groove. The radial expansion lobe can expand radially.

[0019] Preferably, the axial length of the segmented structure of the elastic expansion flap is relatively long, with its distal end fixedly connected to the bone, and the remaining part can be micro-moved. The axial length of the segmented structure needs to be maintained within a reasonable range, so that in addition to the length fixed to the bone at the end, at least 1 / 3 of the length needs to be reserved, and this part of the length structure is elastic.

[0020] Preferably, the number of segmented structures is more than six-segment structures, and a wider axial groove can also be provided, so that even if the bone plate fitting is fixed to the bone plate and the distal end of the bone-side fixation component is in a fixed state, the connection position between the bone-side fixation component and the bone is still a flexible connection structure.

[0021] Preferably, the outer circumference of the sleeve body is provided with an outer wall thread, the thread depth of which is 0.3-0.8mm and the pitch is 1.5-2.2mm. The outer wall thread is used to provide initial anti-rotation capability before final lifting and anchoring.

[0022] Preferably, the bone plate fitting is provided with a mounting part, the mounting part is provided with an inner polygonal hole, the corresponding end of the bone side fixation member is provided with a mounting fitting part, and the mounting fitting part is provided with an outer polygonal shaft segment that matches the inner polygonal hole of the mounting part; The diameter of the inscribed circle of the inner polygonal hole is larger than the diameter of the circumscribed circle of the outer polygonal shaft segment, so that when the outer polygonal shaft segment extends into the inner polygonal hole, there is a uniform circumferential clearance in the radial direction after the two are assembled, allowing a small amount of radial relative displacement. Furthermore, in the pulled-locked state, the bottom end face of the inner polygonal hole is the axial abutment surface, and the end face of the outer polygonal shaft segment can fit with the bottom end face of the inner polygonal hole to transmit axial pressure.

[0023] Preferably, the number of axial grooves is 2-9, and the multiple axial grooves are evenly distributed along the circumference of the sleeve body.

[0024] Preferably, the skeletal fixation device is made of a biodegradable material, including at least one of polylactic acid (PLA), polyglycolic acid (PGA), polylactic-co-glycolic acid copolymer (PLGA), chitosan, silk protein, or magnesium alloy.

[0025] Preferably, the lifting unit includes a flexible connecting structure disposed at a first end, a locking engagement structure disposed at a second end, and an intermediate connecting structure connecting the flexible connecting structure and the locking engagement structure. The flexible connection structure includes a conical structure, the outer periphery of which is provided with a conical surface, which is connected to a radial expansion portion for pressing against and expanding the radial expansion portion during axial movement; The locking engagement structure includes a linear groove unit, which comprises a plurality of continuously and evenly distributed linear grooves arranged along the axial direction. The linear grooves are used to engage with the one-way locking part to achieve one-way locking.

[0026] Preferably, the distal inner side of the skeletal fixation member is provided with a limiting protrusion, and the distal end of the lifting unit is provided with a limiting structure that cooperates with the limiting protrusion; the limiting protrusion and the limiting structure cooperate to prevent the lifting unit from accidentally dislodging from the distal end after it is fully inserted into the skeletal fixation member.

[0027] Preferably, the lifting unit is a solid rod structure integrally machined, and the cross-section of the lifting unit is a regular shape; the cross-section of the lifting unit is at least one regular shape selected from circles, rectangles, and regular polygons, and at least one side is provided with a flat surface for machining straight grooves.

[0028] The linear groove unit is arranged along the axial direction of the lifting unit, and the axial length of the linear groove unit is greater than the axial length of the one-way locking part to ensure that there are continuous locking points within the lifting stroke. The bearing surface of the linear groove and the locking surface of the one-way locking part are a planar contact fit structure that fits each other.

[0029] Furthermore, the present invention also provides a method for using bone plate fastening screws, comprising the following steps: S1. Insert the bone fixation piece into the pre-drilled bone through hole. S2. Align the fixation holes of the bone plate with the implanted bone fixation device, and then place the bone plate fitting into the fixation holes of the bone plate to initially position it. S3. Place one end of the lifting unit with the locking engagement structure on the outside and the other end with the flexible connection structure on the inside. The lifting unit is pre-fixed to the bone side fixation piece. Pass the inside of the lifting unit through the hollow interior of the bone side fixation piece until the flexible connection structure is completely inserted into the radial expansion part of the bone side fixation piece. The lifting unit and the bone side fixation piece are then simultaneously inserted into the bone through hole. S4. Clamp the outer end of the lifting unit, and then apply a continuous pulling force to make the flexible connection structure of the lifting unit press against the radial expansion part, causing it to expand radially and press against the bone hole wall; while the locking fit structure of the lifting unit contacts the one-way locking part of the bone plate fitment, and they mesh with each other to achieve axial locking. S5. Control the lifting force according to usage requirements to achieve preset tension and automatic locking.

[0030] Compared with the prior art, the embodiments of the present invention provide a bone plate fastening screw for a stable connection and a method for using it. The present invention has the following beneficial effects: 1. This invention abandons the traditional rigid threaded locking method, and achieves anchoring by driving the radial expansion part through the lifting unit, and locks it through the one-way locking part; there is no rigid friction pair such as threads that slide continuously relative to each other, thus eliminating the possibility of metal or polymer debris generated by friction from the mechanical structure principle.

[0031] 2. The fixation system of this invention possesses multi-level flexibility: 1) Radial flexibility: The radial expansion flap of the bone-side fixation member can elastically expand and contract with the radial deformation of the bone hole wall; 2) Interface flexibility: The elastic coating or low-modulus material body on the mating surface of the bone plate can absorb axial micro-movements between the bone plate and the bone; 3) Locking flexibility: The surface contact engagement between the wedge and the rack allows for a small amount of elastic slippage. Through the synergy of these three aspects, the fixation system can conform to the physiological micro-movements of the bone, transforming them into benign mechanical stimuli that promote healing, rather than destructive forces that lead to loosening and inflammation.

[0032] 3. This invention improves surgical operability and fixation reliability. 1) Simplified operation: The surgeon only needs to perform a single lifting action to simultaneously complete bone anchoring, bone plate clamping, and system locking, greatly improving surgical efficiency; 2) The virtual coplanar design of the wedge top ensures that multiple teeth are simultaneously and evenly stressed; its large-area planar contact with the rack ensures uniform stress distribution, excellent fatigue resistance, and stepless adjustment and stable maintenance of locking tension; 3) The shallow thread and tool interface design at the proximal end of the bone-side fixation member enables convenient and stable pre-positioning, laying the foundation for subsequent expansion anchoring. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the main structure of one embodiment of the present invention; Figure 2 This is a schematic diagram of the system connection during use according to one embodiment of the present invention; Figure 3 For the present invention Figure 1 A cross-sectional view along the AA direction; Figure 4 This is a three-dimensional structural diagram of a bone plate mating component according to one embodiment of the present invention; Figure 5 This is an axial sectional view of a bone plate fitting according to one embodiment of the present invention; Figure 6 For the present invention Figure 5A magnified schematic diagram of the local structure at point B; Figure 7 This is a three-dimensional structural diagram of one embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of a bone-side fixation member according to one embodiment of the present invention; Figure 9 This is a schematic diagram of the structure of one embodiment of the bone-side fixation mounting and mating part of the present invention; Figure 10 This is a schematic diagram of the external wall thread structure of one embodiment of the present invention; Figure 11 This is a schematic diagram of the lifting unit according to one embodiment of the present invention; Figure 12 This is a schematic diagram of the structure of a linear groove unit according to one embodiment of the present invention; Figure 13 This is a schematic diagram of the cross-sectional shape of an embodiment of the locking and engaging structure of the lifting unit of the present invention; Figure 14 This is a schematic diagram of the connection state of the bone plate fastening screws in one embodiment of the present invention.

[0035] Explanation of symbols in the diagram: 1. Bone plate mating parts; 11. One-way locking part; 12. Mounting part; 121. Mounting hole; 13. Main body; 14. Wedge-type locking unit; 141. Wedge; 142. Locking surface; 143. Guide slope; 15. Elastic beam; 16. Assembly surface; 2. Skeletal side fixation component; 21. Radial expansion part; 211. Radial expansion structure; 212. Axial groove; 213. Radial expansion flap; 22. Sleeve body; 23. Mounting mating part; 24. External wall thread; 25. Limiting protrusion; 3. Lifting unit; 31. Flexible connection structure; 311. Conical surface; 32. Locking fit structure; 321. Straight groove unit; 322. Straight groove; 323. Bearing surface; 324. Passing surface; 33. Intermediate connection structure; 4. Bone plate; 5. Skeleton. Detailed Implementation

[0036] To make the technical problem to be solved, the technical solution, and the beneficial effects of this application clearer, the following describes in further detail a bone plate fastening screw and its usage method provided in this application, in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0037] Example 1 Please see Figure 1 , Figure 2The present invention provides a bone plate fastening screw, including a bone plate fitting 1 and a bone side fixation member 2. A lifting unit 3 is connected between the bone plate fitting 1 and the bone side fixation member 2. Through the lifting action of the lifting unit 3, the radial expansion anchoring of the bone side and the axial compression and locking between the bone plate fitting 1 and the bone side fixation member 2 are realized simultaneously. The bone plate fitting 1 is provided with an axial through hole for the lifting unit 3 to pass through, and a one-way locking part 11 is provided on the hole wall of the axial through hole. The bone-side fixation member 2 is a hollow tubular structure, and the bone-side fixation member 2 includes a radial expansion portion 21; The lifting unit 3 is axially movable and passes through the inner periphery of the bone plate fitting 1 and the bone side fixation member 2. The lifting unit 3 includes a flexible connecting structure 31 at the distal end and a locking fitting structure 32 at the proximal end. The flexible connecting structure 31 cooperates with the radial expansion part 21, and the locking fitting structure 32 cooperates with the one-way locking part 11. By lifting the lifting unit 3 towards the proximal end, the radial expansion part 21 can be synchronously driven to expand to anchor to the bone, and the locking fitting structure 32 can be engaged with the one-way locking part 11, thereby fastening the bone plate 4 to the bone 5.

[0038] This invention provides a securely connected bone plate fastening screw. A lifting unit 3 connects the bone plate fitting 1 and the bone-side fixation member 2 to the bone 5, thus fixing the bone plate 4 to the bone 5. The flexible connection structure 31 of the lifting unit 3 engages with the radial expansion portion 21 of the bone-side fixation member 2, allowing the radial expansion portion 21 to expand and closely adhere to the inner wall of the bone 5. This not only avoids rigid contact but also ensures a stable and reliable connection without relative displacement wear. The outer wall of the bone-side fixation member can undergo slight radial expansion and contraction with bone deformation, and the bone plate fitting 1 can adapt to the axial deformation of the bone. All three components work together to achieve flexible adaptation. The flexible interlocking of the one-way locking portion 11 of the bone plate fitting 1 and the locking engagement structure 32 of the lifting unit 3 locks in a manner that allows for slight displacement without thread wear, reducing friction debris and resolving complications such as inflammation and foreign body reactions caused by debris in existing technologies.

[0039] The bone plate fastening screw provided in this embodiment of the invention provides a new structure that is different from traditional threaded fixation through the separately set bone plate mating part 1, bone side fixation part 2 and lifting unit 3 connecting the two. Firstly, the fastening screw structure simplifies the surgical procedure. The surgeon can first implant the bone-side fixator into the bone, then place the bone plate fitting on the bone plate, and finally complete the bone anchoring, bone plate clamping, and system locking simultaneously with a single lifting action, improving surgical efficiency and controllability. Secondly, a flexible fixation mechanism is established. The radial expansion anchoring method driven by the lifting unit 3, as well as the elastic or surface contact fit between the bone-side fitting and the bone plate, can absorb and adapt to the physiological micro-movements between the bone and the bone plate, transforming harmful friction into elastic deformation. Thirdly, it avoids the rigid friction between traditional threaded pairs, eliminating the structural basis for metal or polymer debris, and reducing the risk of postoperative complications such as inflammation and loosening. Finally, the modular design of this invention facilitates clinical selection, allowing for flexible matching of bone-side fixators 2 and bone plate fittings 1 of different sizes or materials according to the bone quality and bone plate type of different patients.

[0040] In this embodiment, the distal and proximal portions are defined as follows: the end furthest from the doctor is the distal end, and the end closest to the doctor is the proximal end.

[0041] In this embodiment, as Figure 2 As shown, the bone plate fitting 1 is connected to the fixation hole on the bone plate 4, and the bone-side fixation 2 is connected to the bone 5. The lifting unit 3 not only achieves a stable connection between the three but also achieves initial fixation of the bone plate 4 and the bone 5. This embodiment provides a pull-out flexible bone fastening device that can effectively adapt to the micro-movements of the bone under physiological load, simplifying the surgical procedure. The doctor only needs to perform a single lifting action to simultaneously complete multiple fixation steps, significantly improving surgical efficiency and reliability.

[0042] like Figure 3 , Figure 4 As shown, the bone plate fitting 1 includes a main body 13, the interior of which is provided with an axial through hole. A one-way locking part 11 is provided on the hole wall of the axial through hole. The one-way locking part 11 is adapted to and connected to the locking fit structure 32 of the lifting unit 3. The one-way locking part 11 includes at least one wedge-type locking unit 14 arranged axially along the axial through hole. The wedge-type locking unit 14 includes a plurality of continuously and evenly distributed protruding wedges 141.

[0043] Specifically, in this embodiment, the bone plate fitting 1 is an overall conical sleeve structure. The one-way locking part 11 is located inside the main body 13, and the wedge-type locking unit 14 is a plurality of radial protrusions on the inner wall of the axial through hole. The protrusions cooperate with the corresponding grooves on the outer wall of the lifting unit 3 to form a locking fit structure. They cooperate and fit together to form a one-way locking structure, which is used to restrict the axial movement of the fastening nail, effectively prevent the lifting unit 3 from swaying or jamming during the locking process, and ensure the linearity and stability of the movement.

[0044] The wedge-type locking unit 14 includes a plurality of protruding wedge structures arranged radially along the main body 13. The plurality of wedges 141 are evenly distributed and continuously progressively arranged along the axial direction to form a progressive locking system that can provide multiple locking positions. It is connected to the locking engagement structure 32 of the lifting unit 3 and engages with each other, thereby providing a continuous, multiple locking point. This allows the doctor to make stepless adjustments and tension control during the lifting process. Moreover, the doctor can pull the lifting unit to the most ideal tension state according to the feel or instrument reading.

[0045] In this embodiment, as Figures 4-6 As shown, each wedge 141 includes a locking surface 142 and a guide ramp 143. The locking surface 142 is the proximal end face of the wedge 141, which is the "working surface" that performs the locking function. The locking angle α of the locking surface 142 is the angle between the normal direction of the ramp towards the proximal end and the axial direction of the lifting unit 3 towards the proximal end. The range of the locking angle is: 0° ≤ α ≤ 20°. The guide ramp 143 is the distal end face of the wedge 141, which is the guide surface that ensures unidirectional passage. The guide angle β of the guide ramp 143 is the angle between the normal direction of the ramp towards the distal end and the axial direction of the lifting unit 3 towards the distal end. The range of the guide angle is: 20° ≤ β ≤ 40°, and satisfies: α < β, and β - α > 5°.

[0046] In this embodiment, the design principles for the locking angle and guide angle of each wedge 141 are as follows: When α = 0°, the locking surface 142 is perpendicular to the axis of the lifting unit 3, which theoretically provides the strongest self-locking capability. However, it requires a greater elastic deformation force during engagement and disengagement, and places stricter requirements on the material.

[0047] When α > 0°, the locking surface 142 becomes a small slope. In the locked state, the force F exerted on the lifting unit 3 towards the distal end can be decomposed into a normal force Fn perpendicular to the slope and a component force Fs parallel to the slope. The direction of Fs is towards the interior of the slope, attempting to "press" the wedge 141 deeper into the groove, thereby creating a self-increasing effect and making the locking more secure.

[0048] The smaller the angle α, the more significant the self-increasing effect and the more reliable the locking. However, if α is too small (e.g., close to 0°), the manufacturing precision requirement is high and the guidance may be affected. α = 20° ensures the reliability of the locking and prevents the component force Fs from pointing outward due to an excessively large angle, thus creating a "slippage" tendency.

[0049] While ensuring that the wedge 141 can slide smoothly out of the groove, the guide angle should be increased as much as possible to reduce sliding resistance. The larger the β angle, the greater the radial component of the force exerted by the near end face of the groove on the guide ramp 143 when the lifting unit 3 moves towards the proximal end. This can more effectively force the wedge 141 to undergo radial elastic deformation, thus easily "climbing" out of the current groove. The significant difference between the β angle and the α angle can geometrically and physically distinguish between the "locked" and "passing" states, ensuring the reliability of different actions.

[0050] Furthermore, as a preferred embodiment, the locking angle α of the wedge block 141 is 8°, and the inclined surface is reinforced to have high hardness and wear resistance; the guide angle β is 35°, and the difference between the two is 27°, which is much greater than 5°, ensuring unidirectional passage and separation of locking.

[0051] Furthermore, in the locked state, the locking surface 142 and the corresponding bearing surface of the groove of the locking engagement structure 32 of the lifting unit 3 are parallel to each other, thereby ensuring that the two structures are in surface contact rather than line contact or point contact when locked, which greatly increases the contact area, reduces local pressure, and improves the durability and fatigue resistance of the locking structure.

[0052] In this embodiment, two independent wedge-type locking units 14 are provided in the circumferential direction along the axial through hole. The two wedge-type locking units 14 are evenly distributed in the circumferential direction along the axial hole. Each wedge-type locking unit 14 includes four evenly distributed wedges 141. The cross-section of each wedge 141 is approximately triangular. The four wedges 141 extend continuously and are evenly distributed in the axial direction to form a four-level locking. Thus, when the lifting unit 3 is connected to the wedges 141, there are four clear and graded locking positions, thereby realizing the step-by-step control of tension.

[0053] Furthermore, the protruding tops of the wedges 141 in all wedge-type locking units 14 are precisely machined to be located on the same plane parallel to the axis of the axial through hole. In this embodiment, the protruding tops of the wedges 141 refer to the innermost radial side of the wedges 141, and the locking surfaces 142 of different wedges 141 in the same circumferential group of wedge-type locking units 14 are parallel to each other, as are the guide slopes 143. The axial extension direction of the wedges 141 is a straight line, which not only simplifies the structure and makes manufacturing easier, but also ensures consistent interaction with the linearly arranged matching grooves of the lifting unit 3, resulting in smooth movement without jamming. This ensures that when the lifting unit 3 is inserted, its linearly arranged grooves can simultaneously and uniformly contact and engage with all the wedges 141, avoiding sequential engagement, instantaneous off-center loading, or movement interference caused by height or angle deviations. This structurally guarantees the smoothness and stability of the locking process, providing the operator with a clear and consistent operating feel.

[0054] Furthermore, as a preferred embodiment, the cross-section of each wedge 141 is approximately triangular or trapezoidal, and its ends may be designed with rounded corners.

[0055] Furthermore, as a preferred embodiment, 1-6 wedge-type locking units 14 can be evenly distributed along the circumferential direction of the axial through hole. The arrangement of a single locking unit is suitable for low loads or small bones, while two or more locking units are suitable for medium to high loads or larger bones. Their even distribution along the circumferential direction of the axial hole can form a symmetrical locking force. In use, it is preferable to set 3 or 4 units, which results in more uniform force distribution, strong mechanical stability, and lower processing difficulty. This can effectively prevent the lifting unit from swaying or jamming during the locking process, ensuring the linearity and stability of the movement. Moreover, when the lifting unit 3 moves upward, the bearing surfaces 323 of each groove on its locking mating structure 32 can simultaneously contact the tops of all wedges 141, ensuring that all wedges begin elastic deformation and bear load at the same moment. This fundamentally avoids instantaneous uneven loading, abnormal noise, or jamming caused by asynchronous contact, making the doctor's lifting operation smooth, consistent, and linear.

[0056] In a preferred embodiment of the present invention, the one-way locking part 11 protrudes from the wall of the axially penetrating hole and is adapted to engage with the locking engagement structure 32 of the lifting unit 3. The one-way locking part 11 includes at least one wedge-type locking unit 14, which extends axially along the axially penetrating hole and includes a plurality of protruding wedges 141 continuously distributed axially along the axially penetrating hole. By connecting the one-way locking part 11 and the locking engagement structure of the lifting unit 3 to form an engagement pair, not only is reliable one-way locking and stepless tension adjustment achieved, but also the locking force is transmitted through surface contact, resulting in uniform stress distribution. This avoids fretting wear or structural fatigue caused by stress concentration, significantly improving fatigue resistance and long-term stability.

[0057] Furthermore, such as Figure 5 As shown, the one-way locking part 11 is connected to the main body part 13 through the elastic beam 15, and the axial length of the elastic beam 15 is less than the axial length of the one-way locking part 11.

[0058] Specifically, each wedge-type locking unit 14 is connected to the outer peripheral main body 13 via an elastic beam 15. The distal end of the wedge-type locking unit 14 is connected to the elastic beam 15, and the proximal end of the wedge-type locking unit 14 is suspended and has a gap with the main body 13. The wedge 141 has the ability to deform elastically in the radial direction, so that the deformation of the elastic beam 15 can be used to provide the radial movement space required by the wedge 141, providing the basis for the realization of the one-way locking function.

[0059] Furthermore, such as Figure 4 , Figure 5 As shown, the elastic beam 15 is a slender cantilever beam structure formed on the main body 13, with one end integrally connected to the main body 13 and the other end bearing the wedge-type locking unit 14.

[0060] In this embodiment, the axial length of the elastic beam 15 is designed to be less than the axial length of the wedge-type locking unit 14 it supports, so that when the locking engagement structure 32 of the lifting unit 3 interacts with the wedge 141, the radial displacement of the wedge 141 is mainly provided by the bending deformation of the wedge-type locking unit 14 itself within its longer axial range, while the elastic beam 15 mainly serves as a hinge and support.

[0061] This embodiment provides several advantages by using the elastic beam 15 to provide the deformation mode of the wedge-type locking unit 14: First, it allows multiple wedges 141 to deform in a coordinated manner, ensuring smooth and unhindered engagement / disengagement with the groove of the lifting unit 3; Second, it allows deformation and stress to be more evenly distributed along the entire length of the wedge-type locking unit 14, significantly reducing the risk of stress concentration at the root of the elastic beam 15, thereby greatly improving the cyclic load resistance and long-term reliability of the entire one-way locking mechanism; Third, the relatively short elastic beam 15 has relatively high stiffness, which helps maintain the precise geometric position of the one-way locking part 11 in the unloaded state.

[0062] In this embodiment, as Figure 4 , Figure 5As shown, the outer side of the end of the main body 13 is provided with an assembly surface 16 that mates with the corresponding fixing hole of the bone plate 4. The assembly surface 16 has a conical structure, which contacts and mates with the corresponding conical fixing hole on the bone plate 4. The assembly surface 16 and the conical hole on the bone plate 4 mate to form a "Mohs taper" connection. When the lifting unit 3 is pulled in and the fastening pin is tightened, the entire fastening pin system generates axial pressure. The conical surface mating can produce two key functions: First, it generates a radial component force, causing the bone plate material to produce a small elastic deformation, wrapping the bone plate mating part 1, forming static friction, and preventing the bone plate mating part 1 from rotating or coming out relative to the bone plate 4 when there is no resistance force when there is no relative sliding between the contact surfaces; Second, it generates an axial component force, pressing the bone plate 4 onto the surface of the bone 5, initially fitting and achieving initial stability. Compared to the point or line contact method of the current threaded connection, the surface contact method of this embodiment results in a more uniform stress distribution, which greatly reduces the risk of fracture of the bone plate 4 due to stress concentration; at the same time, it makes the force distribution more stable and reliable, further improving the fixation effect.

[0063] Specifically, in this embodiment, the tapered surface of the assembly surface 16 has a taper of 1:8, and the tapered surface is polished to have a high degree of smoothness, so as to form a tight surface contact and self-locking fit with the corresponding 1:8 tapered fixing hole on the bone plate 4, resulting in a stable connection.

[0064] Furthermore, as a preferred embodiment, the taper of the conical surface of the mounting surface 16 is designed to be in the range of 1:5 to 1:10. Too small a taper (e.g., 1:20) may result in insufficient self-locking force, while too large a taper (e.g., 1:3) may cause the head to sink excessively into the bone plate hole, leading to stress concentration in the bone plate 4 or installation difficulties. By selecting a taper of 1:5 to 1:10, sufficient axial locking force can be provided while ensuring a moderate installation depth and forming a large surface contact with the bone plate 4.

[0065] Furthermore, in a preferred embodiment, both the mounting surface 16 and the fixing hole mating surface on the bone plate 4 are conical or spherical curved surfaces. This is to allow for a large-area geometric fit and surface contact with the corresponding fixing holes machined on the bone plate 4. When the lifting unit 3 is tightened and applies an axial clamping force to the entire system, the normal pressure generated between the mounting surface and the bone plate hole can be decomposed into axial and radial components. The axial component stably presses the bone plate 4 onto the surface of the bone 5; the radial component creates a tight press-fit between the bone plate mating part 1 and the bone plate 4, forming a static friction self-locking mechanism that effectively resists rotation and disengagement. Moreover, the designed mounting surface provides a basis for subsequent application of an elastic damping coating or the use of a low-elasticity modulus material, together forming a flexible interfacial layer that absorbs physiological micro-movements between the bone plate and the bone.

[0066] In this embodiment, the bone plate fitting 1 is integrally manufactured using polymer materials, such as polyphenylene ether ketone (PPENK), polyarylether sulfone ketone (PPESK), medical grade polyether ether ketone (PEEK), or composite materials of the above materials and carbon fiber.

[0067] Specifically, the main body 13 is made of a biocompatible polymer material, the elastic modulus of which is lower than that of titanium alloy. The polymer material includes polyetheretherketone (PEEK) or polyphenylene ether ketone (PPENK).

[0068] In this embodiment, the main body 13 is made of PEEK, PPENK, or their carbon fiber composite materials. The elastic modulus of these polymer materials (the elastic modulus of PEEK carbon fiber composite materials can be controlled to be 15-30 GPa) is much lower than that of titanium alloys used for bone plates or traditional screws (approximately 110 GPa), and is closer to that of cortical bone (approximately 10-20 GPa). The main body 13 can thus act as a built-in stress buffer. When the bone bears load, the load is transferred to the bone plate mating member 1 through the bone plate 4. The slight elastic deformation of the material of the bone plate mating member 1 can absorb and redistribute part of the stress, reducing or avoiding the "stress shielding" effect common in pure metal systems, and reducing the risk of osteoporosis and refracture caused by the bone not being under stress.

[0069] Furthermore, as a preferred embodiment of the present invention, to further optimize the interfacial mechanical properties, an elastic damping coating can be added to the aforementioned assembly surface 16, for example, a medical silicone rubber coating with a thickness of 0.1-0.2 mm. By providing the elastic coating, the assembly surface 16 can undergo minute deformation when pressed against the fixation hole of the bone plate 4, absorbing the relative displacement between the bone plate 4 and the bone 5 and avoiding rigid friction. When physiological micro-movements of several micrometers to tens of micrometers occur between the bone 5 and the bone plate 1, the elastic coating can absorb and dissipate this energy through its own shear deformation and compressive deformation, rather than converting it into hard friction and wear particles between the bone plate hole and the fixation device. This allows for better filling of the microscopic gaps between the bone plate mating part 1 and the fixation hole of the bone plate 4, forming a tight interface. This helps inhibit the ingrowth of fibrous connective tissue and reduces the probability of difficulty in removal due to fibrous encapsulation later. Moreover, through the dynamic damping effect, it can attenuate the vibrations generated by the bone during the patient's daily activities such as walking, providing a more stable mechanical environment for bone healing.

[0070] Furthermore, such as Figure 5 , Figure 7As shown, the bone plate fitting 1 has a mounting part 12, which is located at the distal end of the main body 13 and at the end near the bone-side fixator. The mounting part 12 has a mounting hole 121. After the final fastening screw is tightened, it is connected to the end of the bone-side fixator 2 through the mounting hole 121. The proximal end of the bone-side fixator 2 is inserted into the mounting hole 121, thereby further transforming the bone plate fitting 1 and the bone-side fixator 2, which are connected by tension through the lifting unit 3, into a single connected unit.

[0071] Specifically, as a preferred embodiment of the present invention, such as Figure 5 As shown, the mounting hole 121 provided in the mounting part 12 is an inner polygonal hole structure, and the inner polygonal hole is a regular polygon structure.

[0072] Furthermore, as a preferred embodiment, the connection between the mounting hole 121 and the end of the bone-side fixator 2 can be a clearance fit. Preferably, the two can move radially freely or have a relatively large gap. The large gap between the inner wall of the mounting hole 121 and the outer wall of the end of the bone-side fixator 2 allows for axial contact only, thus achieving a better flexible connection. The structure of the mounting hole 121 can be a regular hexagonal interface structure, and the specific shape and size of the mounting hole and the mounting structure at the end of the bone-side fixator can also be flexibly adjusted according to actual usage requirements.

[0073] In this embodiment, as Figure 3 As shown, the bone-side fixation member 2 fixes the bone side of the fastening nail. The bone-side fixation member 2 is connected to the lifting unit 3. The radial expansion part 21 provided on the bone-side fixation member 2 converts the axial movement of the lifting unit 3 into controllable radial expansion, so as to achieve close fit of the bone and enhance the fixation stability.

[0074] Specifically, such as Figure 8 , Figure 9 As shown, the bone-side fixation member 2 includes a sleeve body 22 with a circular cross-section. A radial expansion portion 21 is provided at the first end of the sleeve body 22, which is located away from the bone plate 4. The second end of the sleeve body 22 is provided with an installation mating portion 23 that is adapted to and connected to the installation portion 12 of the bone plate mating member 1. The installation mating portion 23 at the proximal end of the bone-side fixation member 2 can be inserted into and snapped into the installation hole 121.

[0075] In this embodiment, the mounting mating part 23 is provided with an outer polygonal shaft segment that is adapted to the inner polygonal hole of the mounting part 12. The outer polygonal shaft segment is provided at the proximal end of the bone-side fixation member 2. The outer polygonal shaft segment preferably has the same regular polygonal structure as the inner polygonal hole.

[0076] The diameter of the inscribed circle of the inner polygonal hole is larger than the diameter of the circumscribed circle of the outer polygonal shaft segment. This allows for a uniform circumferential clearance in the radial direction after the outer polygonal shaft segment is inserted into the inner polygonal hole, which allows for a small amount of radial relative displacement. Furthermore, in the lifting and locking state, the bottom end face of the inner polygonal hole is an axial abutment surface, and the end face of the outer polygonal shaft segment can fit against the bottom end face of the inner polygonal hole to transmit axial pressure.

[0077] Furthermore, as a preferred embodiment, both the outer polygonal shaft segment and the inner polygonal hole are regular hexagonal structures; that is, the inner polygonal hole is an inner hexagonal hole structure, and the polygonal shaft segment is an outer hexagonal prism structure. The regular hexagonal structure achieves the best balance between ease of machining and structural compactness.

[0078] Furthermore, as a preferred embodiment, the inscribed circle diameter of the inner polygonal hole of the mounting part 12 is D1, and the circumscribed circle diameter of the outer polygonal shaft segment of the mounting mating part 23 is D2. D1 is greater than D2, and the difference between D1 and D2 is in the range of 0.1 mm to 1.0 mm.

[0079] Furthermore, the radial expansion section 21 includes a radial expansion structure 211 and an axial groove 212 arranged along the axial direction of the sleeve body 22. The radial expansion structure 211 is connected to the flexible connection structure 31 of the lifting unit 3. Both the radial expansion structure 211 and the axial groove 212 are arranged along the axial direction of the sleeve body 22, and the axial groove 212 divides the end structure of the sleeve body 22 into the radial expansion structure 211. The radial expansion structure 211 is a radial expansion petal 213 formed by dividing the axial groove, and the radial expansion petal 213 can expand radially. When the expansion surface of the flexible connection structure 31 at the distal end of the lifting unit 3 moves upward and squeezes into the inner wall of the petal, a bending moment is applied to the root of the radial expansion petal 213, forcing the radial expansion petal 213 to bend outward around its root, and the tip of the petal warps outward radially, so that the sleeve body 22 can be adapted to bone holes of different diameters.

[0080] In this embodiment, the axial groove 212 is a groove or slot structure opened along the axial direction of the sleeve body 22. The axial groove 212 is a long rectangular structure. The length of the axial groove 212 is less than the length of the sleeve body 22. At least two axial grooves 212 are provided circumferentially at the end of the sleeve body 22. The axial groove 212 divides the far end of the sleeve body 22 into several independent "petal" structures. The number of axial grooves 212 matches the number of "petals" set in the radial expansion petals 213, and the shape of the radial expansion petals 213 is formed by the division of the axial grooves 212.

[0081] Specifically, the end of the sleeve body 22 is provided with four axial grooves 212 of equal length and evenly distributed along the circumference. The radial expansion lobe 213 is divided into four identical independent lobe structures by the axial grooves. It is elastic and can bend and rebound. When an external load is applied to the end of the sleeve body 22, this load generates a concentrated bending moment in the root region of the radial expansion lobe 213, forcing the entire radial expansion lobe 213 to undergo a controllable elastic bending deformation toward the radially outward around its root.

[0082] In this embodiment, the length of the axial groove 212 is approximately one-third of the total length of the sleeve body 22. The limitation of the length range of the axial groove 212 can restrict radial elastic deformation to the lower part of the sleeve, while the middle and front sections of the sleeve body 22 can maintain a complete circular tube structure. This not only ensures the overall rigidity and guidance during the implantation process, allowing doctors to easily and accurately place the fixation device into the bone hole, but also limits the controllable radial elastic deformation to the distal end of the sleeve, providing a stress-concentrated bending root for the radial expansion flap 213, making the radial expansion action consistent and controllable, while avoiding the risk of overall stiffness reduction and fatigue fracture caused by excessively long grooves.

[0083] Furthermore, each radial expansion flap 213 has a small chamfer on its outer end to facilitate initial insertion into the bone hole.

[0084] In this embodiment, the expansion amplitude of the radial expansion flap 213 is not unlimited, but within a certain numerical range. Its maximum value is determined by the length of the axial groove 212, the thickness of the flap, and the material properties. The limited expansion setting not only ensures the strength of the fixation, but also reduces the splitting damage to the bone caused by excessive expansion. Through the macroscopic interlocking of multiple radial expansion flaps 213 with the trabeculae, rather than the simple compression of the cortex by traditional screws, the sleeve body 22 can form a good anchoring effect with the osteoporotic bone.

[0085] Furthermore, as a preferred embodiment, the number of axial grooves 212 can be set to 2-9, with multiple axial grooves 212 evenly distributed along the circumference of the sleeve body 22. The more axial grooves 212 are provided, the smaller the width of each lobe of the radial expansion lobe 213, the easier it is to bend and deform, and the smaller the required lifting force, but the rigidity of each lobe will be relatively reduced.

[0086] Therefore, in practical use, it is necessary to balance the ease of expansion and the anchoring strength. It is preferable to set 3, 4 or 6 axial grooves 212. When there are two axial grooves 212, the radial expansion petals 213 are composed of two symmetrical petals, which form a "I" shape after expansion. When there are three axial grooves 212, the radial expansion petals 213 are composed of three evenly distributed petals, which form a triangular distribution after expansion and have excellent stability. When there are four axial grooves 212, the radial expansion petals 213 are composed of four symmetrical petals, which form a cross or square shape after expansion and can provide balanced radial support force.

[0087] Furthermore, as a preferred embodiment of the present invention, the radial expansion flap 213 provided in the radial expansion portion 21 can also adopt an elastic expansion flap structure, which realizes radial outward expansion. The elastic expansion flap can expand outward under pressure, thereby increasing the radial dimension.

[0088] Specifically, the segmented structure of the elastic expansion flap is made of elastic material, with a relatively long axial length. Its distal end is fixedly connected to the bone, while the remaining part can be micro-moved. When the distal part of the radial expansion flap 213 undergoes elastic bending deformation under the driving action of the lifting unit 3 and presses against the bone wall to achieve anchoring, its proximal part (i.e. the end close to the bone plate fitting 1) still remains a "flexible connecting segment" that can be freely elastically deformed.

[0089] In this embodiment, the axial length of the flap structure needs to be maintained within a reasonable range, so that, in addition to the length fixed to the bone at the end, the axial length of the proximal flexible connecting section of the radial expansion flap 213 after anchoring must account for at least 1 / 3 of its total working length. This part of the flap body, which is rigidly pressed against the bone wall, acts as a built-in elastic tuning structure, allowing the rod of the bone-side fixation member 2 to undergo slight radial displacement or bending within the bone hole without rigidly transmitting stress to the already anchored distal end or the bone plate mating member 1.

[0090] Furthermore, in actual use, the number of segments of the elastic expansion valve can be set according to the differentiated needs of the actual surgical scenario. The number of segments can be adjusted according to different surgical sites, operational requirements, or individual patient differences. By flexibly setting the number of segments, the elastic expansion valve can better match the actual surgery in terms of its shape and tissue compatibility and functional stability after expansion.

[0091] In this embodiment, the number of axial grooves 212 is set to be relatively large, preferably more than 6, and usually 8-12. Multiple subdivided radial expansion lobes 213 together form an approximately "cage-like" or "mesh-like" elastic structure, thus making the number of lobed structures preferably more than six-lobed structures. The advantages of this structural design are: The increased number of segments allows the anchoring force and subsequent adaptive deformation energy to be more evenly distributed over a larger circumferential area of ​​the bone pore wall, reducing local pressure and avoiding damage to osteoporotic bones. The reduced width of a single segment significantly reduces its bending stiffness, making it easier for the entire radial expansion section 21 to undergo coordinated elastic deformation when subjected to lateral forces, thus improving overall compliance. The multi-lobed structure forms a continuous, distributed, elastic interface that can better conform to the irregular shape of the bone hole.

[0092] Furthermore, in a preferred embodiment of the present invention, a wider axial groove 212 can be provided between the radial expansion flaps. The wider groove provides more space for the independent deformation of each radial expansion flap 213, reduces the mutual interference of deformation between flaps, and ensures that each segmented structure can move freely within its elastic range, further releasing internal stress. Even if the bone plate mating part 1 and the bone plate 4 are tightly fitted, and the distal end of the bone-side fixation part 2 is firmly anchored to the bone 5 through the radial expansion flap 213, there is still a "flexible buffer zone" with significant elastic deformation capability in the force transmission path between the two, that is, the rod part of the bone-side fixation part 2 and the proximal part of the radial expansion flap 213.

[0093] The above design ensures that the entire fixation system is not an absolutely rigid whole from the bone plate to the bone, allowing for minor, necessary deformations. This avoids excessive constraints on bone healing caused by rigid connections and reduces stress concentration between the fixation components and the bone, thus lowering the risk of postoperative complications. When the bone bends, twists, or undergoes axial compression due to physiological activities, the resulting minor deformations and energy can be absorbed and dissipated by this "flexible buffer" through the elastic bending deformation of its multi-lobed structure. This maintains a macroscopically stable fixation relationship between the bone plate 4 and the bone 5, while achieving a dynamic, low-stress adaptation at the microscopic mechanical level through the built-in flexible structure of this invention. This fundamentally avoids the contradiction between stress shielding and interfacial fretting corrosion in traditional rigid fixation, providing an ideal mechanical environment for bone healing.

[0094] In this embodiment, the mounting fitting part 23 is located on the side of the sleeve body 22 near the bone plate 4. The mounting fitting part 23 is the mounting structure at the end of the sleeve body 22. Its structure can be set as an external hexagon, external octagon, or other structures. The mounting fitting part 23 can not only provide a force application point for cooperation with the matching hexagonal wrench and other installation tools when the lifting unit 3 is not inserted, so as to initially and gently screw or press the sleeve body 22 into the pre-drilled hole of the bone 5 to obtain an initial, non-tight positioning; at the same time, after the lifting unit 3 is inserted and the lifting operation is performed and locked, it can be adapted and connected to the mounting hole 121 at the end of the bone plate fitting part 1.

[0095] Furthermore, such as Figure 10 As shown, in a preferred embodiment, the outer circumferential side of the second end of the sleeve body 22 is provided with an outer wall thread 24. The outer wall thread 24 is a shallow thread, and its thread depth is less than that of a standard cortical bone screw to reduce cutting and damage to the cortical bone. Its pitch can be greater than that of a standard cortical bone screw to facilitate rapid screwing in and obtaining sufficient initial holding force. By providing the outer wall thread 24, anti-rotational stability can be provided before the lifting unit 3 starts working, rather than bearing the main axial load.

[0096] Specifically, the outer wall thread 24 can be set in the front and middle areas away from the axial groove 212, or evenly distributed along the outer periphery of the sleeve body 22 according to actual usage requirements. In this embodiment, by setting the outer wall thread 24, it can play a guiding role, guiding the sleeve body 22 to enter the bone hole more smoothly when installing the sleeve body, especially when installing cortical bone with high density; it can also play an initial anti-rotation role, providing a certain anti-rotation ability before the lifting unit 3 is tightened and anchored, preventing the sleeve body 22 from rotating in the hole; and it can also achieve auxiliary holding, when used in the cancellous bone area, the outer wall thread 24 can engage with the bone trabeculae, providing additional initial holding force to prevent dislodgement.

[0097] Furthermore, as a preferred embodiment, the thread depth of the outer wall thread 24 is 0.3 mm to 0.8 mm; the pitch is 1.5 mm to 2.2 mm.

[0098] Furthermore, the mounting mating part 23 at the proximal end of the sleeve body 22, the outer wall thread 24, and the axial grooves 212 of a specific number and length at the distal end are designed as a whole to simplify surgical operations and ensure the reliability of final anchoring. During the operation, the surgeon first drives the mounting mating part 23 with a tool (such as a hex wrench) and, with the guidance and anti-rotation effect of the outer wall thread 24, conveniently and securely pre-positions the bone-side fixator 2 in the bone channel. This step achieves initial positioning and temporary fixation. Subsequently, under the action of the lifting unit 3, the radial expansion flaps 213 formed by the axial grooves 212 at the distal end undergo controllable and uniform radial expansion. The pre-positioned connection at the proximal end is a prerequisite for ensuring that each expansion flap at the distal end can deform symmetrically and synchronously, thereby achieving uniform anchoring; conversely, reliable expansion anchoring at the distal end can provide long-term stable mechanical support for the proximal connection structure.

[0099] Furthermore, as a preferred embodiment, the skeletal fixation member 2 is made of medical-grade titanium alloy and has a hollow tubular structure with uniform wall thickness.

[0100] In this embodiment, as Figure 3As shown, the lifting unit 3 is a solid rod structure manufactured in one piece. By adopting a solid rod structure manufactured in one piece, the lifting unit 3 ensures its overall rigidity and dimensional stability when subjected to lifting force, avoiding loosening or deformation that may occur due to connection or assembly. The lifting unit 3 dynamically connects the bone plate fitting 1 and the bone side fixation member 2. The lifting unit 3 is dynamically connected to the one-way locking part 11 of the bone plate fitting 1 through the locking fitting structure 32, and the lifting unit 3 is dynamically connected to the radial expansion part 21 of the bone side fixation member 2 through the flexible connection structure 31.

[0101] Specifically, such as Figure 11 As shown, the lifting unit 3 includes a flexible connecting structure 31 disposed at the first end, a locking engagement structure 32 disposed at the second end, and an intermediate connecting structure 33 connecting the flexible connecting structure 31 and the locking engagement structure 32.

[0102] In this embodiment, the flexible connection structure 31 is disposed on the bone side and inside the sleeve body 22. The flexible connection structure 31 includes a conical structure, and the outer periphery of the conical structure is provided with a conical surface 311. The conical surface 311 is connected to the radial expansion portion 21 of the bone side fixation member 2 and is used to press against and expand the radial expansion portion 21 when moving axially. The outer periphery of the conical surface 311 is an expansion surface structure. The conical surface can provide a smooth and continuously changing diameter, so that the expansion of the radial expansion petal 213 at the end of the sleeve body 22 is a gradual and controllable process, avoiding step-like impact and allowing the doctor to obtain a good feel.

[0103] Furthermore, the taper of the conical surface 311 is set within a reasonable range, approximately between 5° and 25°. As an expansion structure, its smooth surface ensures that the radial expansion flaps 213 can be smoothly opened. A smaller taper setting means a longer ramp and a longer axial distance, resulting in less radial expansion within the same lifting stroke, but requiring less effort and allowing for more precise control. Conversely, a larger taper setting results in a shorter axial distance, allowing for greater expansion in a shorter stroke, but requiring a larger lifting force. In practical use, the taper size can be set as needed, and the expansion surface on the outer periphery of the conical structure can also be a sphere, a parabolic surface, or other curved surfaces that can generate radial force components.

[0104] In this embodiment, as Figure 11 , Figure 12 As shown, the locking engagement structure 32 is provided at the end of the bone plate. The locking engagement structure 32 includes a linear groove unit 321 that engages with the one-way locking part 11. The linear groove unit 321 includes a plurality of linear grooves 322 that are continuously and evenly distributed and arranged along the axial direction. The linear grooves 322 are used to engage with the one-way locking part 11 to achieve one-way locking.

[0105] The linear groove unit 321 is provided with several linear grooves 322, which are continuously and evenly distributed along the axial direction of the lifting unit 3, forming a precise rack-like structure. The depth, width, and tooth pitch of the linear grooves 322 match the wedge 141 of the one-way locking part 11, and the axial length of the linear groove unit 321 is greater than the axial length of the one-way locking part 11. The bearing surface 323 of the linear groove 322 and the locking surface 142 of the one-way locking part 11 are mutually fitted planar contact structures, and the linear groove unit 321 and the one-way locking part 11 are connected by surface contact. Designing the axial length of the linear groove unit 321 to be greater than the axial length of the one-way locking part 11 provides sufficient and continuous locking position selection for tension adjustment during surgery, ensuring continuous locking points within the lifting stroke and allowing doctors to make stepless adjustments.

[0106] Furthermore, each straight groove 322 includes a load-bearing surface 323 disposed at the far end and a passage surface 324 disposed at the near end. The geometry and angle of each load-bearing surface 323 are matched with the locking surface 142 of the wedge 141 to ensure that the maximum contact area and efficient force transmission are maintained when they are engaged. The passage surface 324 of the straight groove 322 can also be set as an inclined structure, and its angle works in conjunction with the guide inclined surface 143 of the wedge 141 to guide the smooth sliding of the wedge 141.

[0107] In this embodiment, the bearing surface 323 of each groove of the straight groove 322 is set as an 8° inclined plane that is completely parallel to the locking surface 142 of each wedge 141, thereby ensuring ideal surface contact when locking; the through surface 324 of each groove is set as a 35° inclined plane that is adapted to and parallel to the guide inclined plane 143 of each wedge 141. In actual use, the specific inclined plane angle can be adjusted according to the actual angle of the wedge 141.

[0108] In this embodiment, the intermediate connecting structure 33 is a cylindrical structure disposed between the straight groove unit 321 and the conical structure, which serves as a transition and connection. The cylindrical structure is easy to process and has uniform stress distribution.

[0109] Furthermore, as a preferred embodiment, the lifting unit 3 has a regular cross-section, with its front end being a columnar structure, the middle being a cylindrical structure, and the rear end being a conical structure, which facilitates practical use.

[0110] Furthermore, in a preferred embodiment of the present invention, the lifting unit 3 and the bone plate mating component 1 are made of the same biocompatible material. This design contributes to the uniformity of material biocompatibility and may bring benefits in terms of processing synergy. Preferred identical materials include, but are not limited to, polyphenylene ether ketone (PPENK), PPESK, and ultra-high molecular weight polyethylene (UHMWPE). Those skilled in the art will understand that, depending on different mechanical properties and biocompatibility requirements, different material combinations may be used; for example, the lifting unit 3 may use a metal alloy to ensure strength, while the bone plate mating component 1 may use a polymer material or composite material to provide interfacial flexibility.

[0111] Furthermore, such as Figure 13 As shown, in order to ensure that the load-bearing surface 323 of the straight groove 322 can form a stable and large-area surface contact with the locking surface 142 of the one-way locking part 11, the lifting unit 3 is provided with a local section of the straight groove unit 321, and its cross-section preferably adopts multiple shapes that can provide a flat load-bearing surface. Figure 13 Several possible cross-sectional shapes are shown. The cross-sectional shape of the lifting unit 3 can be rectangular, square, or semi-circular with a flat surface. The lifting unit 3 has at least one flat surface and a straight groove 322 is provided on at least one flat surface. Preferably, in actual use, the lifting unit 3 may include at least two opposing flat surfaces and at least two straight grooves 322 are provided on the opposing flat surfaces, such as a rectangular or square cross-section. Furthermore, depending on the number and layout of the wedge-type locking units 14 in the bone plate mating member 1, the straight grooves 322 can be provided on one or more sides of the lifting unit 3 along the circumference. When there are multiple wedge-type locking units 14 and they are distributed circumferentially, the straight grooves 322 can be respectively provided on the corresponding sides of the lifting unit 3 to achieve simultaneous engagement with each wedge.

[0112] Furthermore, in a preferred embodiment, the bottom end of the lifting unit 3, after penetrating the cortex distal to the bone, is a smooth dome structure. The smooth curved surface avoids sharp corners, significantly reducing mechanical stimulation and wear on surrounding soft tissues (tendons, nerves, blood vessels). This structurally cuts off the source of mechanical stimulation / wear, preventing the development of local chronic inflammation and pain. Moreover, in the superficial subcutaneous area, the smooth end allows the soft tissue covering it to slide freely, reducing postoperative tissue adhesion and discomfort during movement, and lowering the risk of postoperative complications.

[0113] Furthermore, such as Figure 3 , Figure 14As shown, the distal end of the bone-side fixation member 2 is provided with a one-way limiting structure that can restrict the axial movement of the lifting unit 3. The one-way limiting structure is provided with a limiting protrusion 25, which is an anti-dislodgement protrusion structure. During the assembly and operation stage from the insertion of the lifting unit 3 into the bone-side fixation member 2 until the final lifting and locking, it prevents the lifting unit 3 from accidentally dislodging from the distal end of the bone-side fixation member 2, thus ensuring the continuity and reliability of the surgical operation.

[0114] Specifically, such as Figure 3 As shown, in this embodiment, the limiting protrusion 25 is provided on the inner wall of the bottom end of the bone-side fixation member 2. The limiting protrusion 25 engages with the outer periphery of the end of the lifting unit 3 for limitation. By limiting the connection between the limiting protrusion 25 and the far end of the lifting unit 3, axial movement is prevented, so that the lifting unit 3 cannot be detached from the bottom of the bone-side fixation member 2.

[0115] Furthermore, as one preferred embodiment, such as Figure 14 As shown, the limiting protrusion 25 is located at the bottom of the bone-side fixation member 2. The limiting protrusion 25 is a wedge-shaped structure arranged around its circumference. The outer periphery of the end of the lifting unit 3 is provided with a groove structure that matches the wedge protrusion. By engaging the limiting protrusion 25 with the groove, the distal end of the lifting unit 3 is locked, achieving one-way locking and restricting the axial movement of the lifting unit 3.

[0116] The structure of this invention utilizes biocompatible polymer materials, features a smooth end design, and reduces the generation of metal wear particles, all of which enhance the biocompatibility of the device and lower the incidence of postoperative acute and chronic pain and inflammation. Furthermore, both the bone plate fitting 1 and the bone side fixation component 2 are made of titanium alloy, and the main structure of the lifting unit 3 is made of carbon fiber composite PEEK material with a silicone rubber elastic coating, making it suitable for adult long bone fractures.

[0117] This invention provides a simple and efficient pull-out flexible bone fixation device with stable structure and easy operation, suitable for bone plate fixation of most fractures. It comprises three core structures: a bone plate fitting 1 (serving as the head), a sleeve-shaped bone-side fixation component 2, and a lifting unit 3. These three components achieve fixation between the bone plate and the bone through a non-threaded flexible fit. Before implantation, one end of the flexible connecting structure 31 of the lifting unit 3 is pre-placed within the radial expansion portion 21 of the bone-side fixation component 2, forming a pre-assembled component. The integrated lifting unit 3 and bone-side fixation component 2 are simultaneously implanted into a pre-drilled bone through-hole, serving as the bone-side anchor point for the entire device. The bone plate fitting 1 is placed within the corresponding fixation hole of the bone plate 4, serving as the interface on the bone plate side. The lifting unit 3 connects the bone plate fitting 1 and the bone-side fixation component 2.

[0118] When the lifting unit 3 is pulled proximally (i.e., away from the bone), the conical structure at the distal end of the lifting unit 3 is squeezed between the radial expansion flaps 213 of the bone-side fixation member 2, forcing the radial expansion flaps 213 to undergo large radial and outward deformation, thereby tightly gripping the bone hole wall and forming a strong mechanical interlock. During the pulling process of the lifting unit 3, its locking engagement structure 32 interacts with the one-way locking part 11 of the bone plate engagement member 1. Once the lifting force loosens or the bone slightly moves and attempts to push the lifting unit 3 back (towards the end away from the operator), the locking mechanism formed by the locking engagement structure 32 and the one-way locking part 11 will be triggered instantly, locking the lifting unit and preventing it from retracting, thereby maintaining the tension established on the lifting unit 3 and ensuring the stability of the fixation. Finally, by mechanically connecting (e.g., by pressing, snapping, or threading) the mounting hole 121 at the end of the bone plate fitting 1 to the outer polygonal shaft segment structure near the end of the bone side fixation member 2, the bone plate fitting 1, the bone side fixation member 2, and the tightened lifting unit 3 are integrated into a whole, thus completing the final fixation of the bone plate 4 and the bone 5.

[0119] Example 2 This invention provides a bone plate fastening screw, whose basic composition, connection relationship, and working principle are the same as those of Embodiment 1. This embodiment is specifically optimized for osteoporosis patients, cancellous bone areas near joints, or biological fixation scenarios with extremely high requirements for micromotion absorption. The main differences between this embodiment and Embodiment 1 are as follows.

[0120] In this embodiment, the main body of the bone plate fitting 1 is made of carbon fiber reinforced polyether ether ketone (CF / PEEK). By adding carbon fiber, the strength and stiffness of the PEEK material are significantly improved, making it more suitable for complex stress parts or osteoporotic environments that require higher mechanical strength.

[0121] In this embodiment, the locking angle α of each wedge 141 of the one-way locking part 11 is adjusted to 5° and the guide angle β is adjusted to 30°. The smaller locking angle α brings a stronger self-locking effect, which is suitable for osteoporotic bones with poor holding force and ensures the locking effect.

[0122] In this embodiment, the distal end of the sleeve body 22 of the bone side fixation member 2 is provided with six axial grooves 212 and six narrower, more flexible radial expansion petals 213. Compared with the four-petal structure set in embodiment 1, the width of each radial expansion petal 213 in the six-petal structure is narrower, making it easier to bend and deform under the same lifting force. The required expansion force is smaller, which can avoid excessive compression of fragile trabeculae. Moreover, more contact petals make the anchoring force distribution more even and dispersed, providing a more stable holding force in low-density bones.

[0123] In this embodiment, since the implanted structure is mainly used in the cancellous bone environment and the six-flap design can provide excellent initial grip, the threaded design on the outer wall of the sleeve body is omitted. The sleeve body 22 is still provided with an external hexagonal structure at one end near the bone plate 4, which is used to insert the pre-drilled hole by pressing rather than screwing during implantation, further reducing the cutting and trauma to the bone tissue.

[0124] Furthermore, in this embodiment, the arrangement of the unspecified parts of the connecting bone plate fastening screw structure can be the same as in Embodiment 1, or those skilled in the art can make adaptive modifications based on Embodiment 1. The specific structural shape and quantity of each component can be adapted and adjusted according to the adjustment requirements of the actual use conditions, thereby adapting to different use conditions. A suitable structural design method can be selected according to the actual needs of the patient.

[0125] Example 3 This invention provides a bone plate fastening screw. The basic composition, connection relationship and working principle of this embodiment are the same as those of Embodiment 1 or Embodiment 2. This embodiment optimizes the interface based on Embodiment 1 or Embodiment 2.

[0126] In this embodiment, a 0.15mm thick medical-grade silicone rubber elastic coating is uniformly coated on the mounting surface 16 at the end of the bone plate mating component 1 using plasma spraying or dip coating processes. This coating acts as a micro-motion absorber and damping layer. After fixation, when a small relative displacement or vibration occurs between the bone plate 4 and the bone 5, the soft silicone rubber layer can absorb and dissipate this energy through its own elastic deformation, rather than generating hard friction and wear particles like in metal-to-metal (or rigid polymer) contact. This effectively reduces stress concentration and potential inflammatory response at the fixation interface, providing a better mechanical environment for bone healing. The coating and the CF / PEEK material body in this embodiment together constitute a dual flexible mechanism of material buffering and interface damping.

[0127] Example 4 This invention provides a bone plate fastening screw, whose basic structure and connection relationship are the same as those in Embodiment 1. The main difference is that in this embodiment, the bone side fixation member 2 is made of a biodegradable polymer material, such as poly-L-lactic acid (PLLA) or racemic polylactic acid (PDLLA).

[0128] In this embodiment, since the bone-side fixation member 2 mainly relies on the elastic expansion of the radial expansion flap 213 to form a macroscopic interlock with the bone, rather than relying on the thread shear force of the traditional screw for fixation, its absolute shear strength requirement for the material is relatively low, and the biodegradable polymer material with a modulus similar to that of the bone can fully meet its mechanical requirements for initial fixation and early bone healing.

[0129] Specifically, the advantage of using biodegradable materials for the bone fixation component 2 in this embodiment is that after fulfilling its fixation function, the bone fixation component 2 can gradually degrade in the body through hydrolysis and other processes, and be absorbed or excreted by the body's metabolism. This fundamentally avoids the need for secondary removal surgery due to long-term implantation, reducing patient pain and surgical risks. Moreover, its degradation cycle can be designed by selecting different biomaterials or adjusting molecular weight, crystallinity, etc., to match the bone healing time of different locations.

[0130] Furthermore, the biodegradable polymeric material used in this embodiment may include at least one of polylactic acid (PLA), polyglycolic acid (PGA), polylactic acid-glycolic acid copolymer (PLGA), chitosan, or silk protein.

[0131] Furthermore, as a preferred embodiment, the skeletal fixation component 2 can also be made of biodegradable magnesium alloys or other biomaterials. Magnesium alloys possess suitable strength and good biocompatibility, and their elastic modulus is close to that of human cortical bone, which can reduce stress shielding effects. Moreover, in the physiological environment within the body, magnesium alloys gradually corrode and degrade, and the degradation products have good biocompatibility. By selecting appropriate magnesium alloy components and processing techniques, the degradation rate of the skeletal fixation component 2 can be controlled, allowing it to maintain structural integrity and provide reliable support during the critical period of bone healing. Subsequently, it can be gradually degraded and absorbed. Furthermore, the magnesium ions released during the degradation process of the magnesium alloy have a biological effect that promotes bone healing, combining multiple advantages such as fixation, absorbability, and repair promotion.

[0132] Example 5 This invention provides a method for using bone plate fastening screws, including the following steps: S1. Insert the bone fixation piece 2 into the pre-drilled bone through hole; S2. Align the fixation hole of the bone plate 4 with the implanted bone fixation piece 2, and then place the bone plate fitting piece 1 into the fixation hole of the bone plate 4 to initially position it. S3. The lifting unit 3 is provided with one end of the locking and engaging structure 32 on the outside and one end of the flexible connecting structure 31 on the inside. The lifting unit 3 is pre-fixed to the bone side fixation member 2. The inside of the lifting unit 3 is passed through the hollow interior of the bone side fixation member 2 until the flexible connecting structure 31 is completely inserted into the radial expansion part 21 of the bone side fixation member 2. The lifting unit 3 and the bone side fixation member 2 are simultaneously inserted into the bone through hole. S4. Clamp the proximal end of the lifting unit 3, and then apply a continuous pulling force to make the flexible connecting structure 31 of the lifting unit 3 press against the radial expansion part 21, causing it to undergo radial elastic expansion and press against the bone hole wall; while the locking engagement structure 32 of the lifting unit 3 contacts the one-way locking part 11 of the bone plate engagement part 1, and they mesh with each other to achieve axial locking. S5. Control the lifting force according to usage requirements to achieve preset tension and automatic locking.

[0133] To address the problems in existing technologies where bone plates and screws are rigidly connected via threads, leading to relative displacement during limb movement, frictional debris generation, and postoperative complications, this invention provides a pull-out bone plate fastening screw and its usage method. The fastening device not only achieves initial strong fixation between the bone plate and bone, but also, through a controllable flexible connection structure, effectively adapts to the micro-movements generated by the bone under physiological load, transforming them into benign stimuli that promote bone healing rather than destructive forces that lead to fixation failure. Simultaneously, the structure simplifies the surgical procedure; the surgeon only needs to perform a single pulling motion to simultaneously complete multiple fixation steps, significantly improving surgical efficiency and reliability.

[0134] In this embodiment, the bone-side fixation member 2 is fixed to the bone 5 through elastic expansion, and the lifting unit 3 is locked to the bone plate mating member 1 through a one-way locking structure. This facilitates surgical operation; simply pulling the lifting unit 3 expands the radial expansion flap 213 of the bone-side fixation member 2, thus fixing the bone-side fixation member 2 to the bone 5 and securing the lifting unit 3 to the bone plate mating member 1. The elastic connection between the lifting unit 3 and the bone plate mating member 1 absorbs minor displacements between the bone 5 and the bone plate 4, avoiding rigid friction between the bone plate mating member 1 and the bone plate 4. This ensures fixation stability while eliminating friction debris and reducing the risk of postoperative complications.

[0135] Example 6 This invention discloses a method for using the bone plate fastening screw provided in Embodiment 1, comprising the following steps: S1. Preparation and Skeletal Drilling First, prepare for the implantation of the device by routinely exposing and reducing the fracture site of the patient, selecting a suitable bone plate 4 and placing it on the surface of the bone 5. Corresponding to the position of the fixation hole of the bone plate 4, use the matching drill bit and guide to drill a through hole in the bone 5 with a diameter matching the bottom diameter of the thread of the bone side fixation member 2. Then, a tap can be used (if the bone is hard) to perform the tapping operation.

[0136] S2, Implanted bone fixation device and lifting unit The pre-assembled bone side fixation component 2 and the lifting unit 3 are implanted as a single unit. Specifically: Using a medical-grade hexagonal wrench, insert the external hexagonal structure at the end of the bone-side fixation piece 2. Then, align the bone end of the sleeve body 22 with the bone hole and gently rotate the wrench to screw the sleeve body 22 into the bone hole. The specific depth of screwing should be such that the non-external hexagonal structure at the end of the sleeve body 22 is exposed on the bone surface. At this point, the sleeve body 22 is initially fixed by its outer wall thread 24, but the radial expansion flap 213 at its end is in its original contracted state and has not yet expanded, thus not forming a final anchor.

[0137] S3, Install the bone plate fitting and bone plate. like Figure 2 , Figure 14 As shown, align the conical fixation hole of the bone plate 4 with the implanted bone side fixation member 2, and then insert the conical surface of the bone plate mating member 1 into the fixation hole of the bone plate 4 to initially position it.

[0138] S4, Perform the lifting operation. Clamp the smooth part protruding from the end of the locking and engaging structure of the lifting unit, and apply a lifting force F to the outward end.

[0139] S5, coordinated operation of all components of the fastener S501, Bone Side Fixation Movement Under the lifting force F of the lifting unit 3, the lifting unit 3 moves outward, and the expansion structure of its internal flexible connection structure 31 moves outward relative to the bone side fixation member 2, like a wedge, forcibly squeezing into the inner wall of the four radial expansion petals 213, causing the four radial expansion petals 213 to undergo uniform, radially outward elastic bending deformation around their roots. The outer surface of the radial expansion petals 213 presses against the wall of the outer bone hole, generating huge radial pressure and tissue interlocking, thereby firmly "anchoring" the sleeve body 22 in the bone. This process converts the axial movement of the lifting unit 3 into the radial expansion and fixation of the sleeve body 22.

[0140] S502, Bone plate mating parts operation As the lifting unit 3 moves outward relative to the bone plate mating part 1, the one-way locking part 11 inside the bone plate mating part 1 activates. The through surface 324 of the straight groove 322 of the lifting unit 3 contacts the guide slope 143 of the wedge 141 and applies a radially inward force. Due to the elasticity of the PEEK material and the design of the β angle, the wedge 141 is easily pressed against the inner wall of the axial hole, undergoing elastic deformation and thus sliding out of the currently engaged groove. As the lifting unit 3 continues to move outward, the wedge 141 resets under the action of elastic restoring force and prepares to engage with the next straight groove 322. During this process, the doctor can hear a continuous, crisp "click" sound (usually three to four sounds), which is the sound produced when the wedge 141 slides through the groove, providing the doctor with clear auditory feedback that the device is working properly and the locking level is increasing.

[0141] S503, Mutual Synergy The continuous lifting force is transmitted through the lifting unit 3. On the one hand, it causes the radial expansion flap 213 of the bone-side fixation member 2 to expand and anchor to the bone 5. On the other hand, it pulls the bone plate mating member 1 outward, pressing the outer hexagonal shaft segment of the bone-side fixation member 2 into the mounting hole 121 at the end of the bone plate mating member 1, thus connecting the bone plate mating member 1 with the bone-side fixation member 2 and preventing the outer hexagonal shaft segment from being exposed and in contact with the bone. At the same time, under the action of the pulling force, the conical surface of the bone plate mating member 1 fits more and more tightly with the conical hole of the bone plate 4, ultimately forming a strong conical self-locking and pressing the bone plate 4 tightly onto the surface of the bone 5.

[0142] S6, Achieve preset tension and automatic locking. Stop pulling when the lifting force reaches the preset value of the instrument, or when the doctor judges by touch that the bone plate has completely adhered to the bone and can no longer be moved.

[0143] At this point, when the lifting stops, the elastic restoring force of the bone attempts to push the lifting unit 3 inward, while the locking surface 142 of the wedge 141, under the action of the elastic force, immediately engages tightly with the distal bearing surface of the groove. Because angle α is acute and very small, a strong self-tightening effect is generated, forming an irreversible mechanical interference, like a ratchet, preventing any retraction of the lifting unit 3. Thus, the device establishes and maintains a stable, continuous fixed tension within the body, maintaining the locked state.

[0144] S7, Trimming Finally, at the surface position close to the outer end of the bone plate fitting 1, cut off the excess outer end portion of the lifting unit 3.

[0145] S8, Close the incision After routine irrigation and suturing of the incision, the surgery was completed.

[0146] The device and its usage method provided in this embodiment complete three key functions—bone anchoring, plate clamping, and unidirectional locking—in a single, simple lifting motion. The device is suitable for most cortical and cancellous bones. The plate fitting 1 provides excellent stress buffering, ensuring reliable fixation of the entire system. By simplifying multiple steps such as screwing in, applying pressure, and locking into a single lifting motion, the operation process is greatly streamlined, shortening surgical time. The multi-level locking mechanism allows for stepless tension adjustment, giving surgeons greater control freedom.

[0147] Furthermore, the method of using the bone plate fastening screw provided in Embodiment 2 of the present invention has basically the same surgical steps as that in Embodiment 5, but has the following characteristics due to design improvements: Bone fixation implantation: Since the sleeve body 22 has no external thread, its hexagonal structure can be pressed into the hole pre-drilled in the cancellous bone area using a tool, making the operation gentler and causing less damage to bone tissue.

[0148] Lifting sensation: Due to the presence of the silicone rubber coating, the bone plate mating part 1 and the bone plate 4 have a certain "buffering sensation" when finally locked together, rather than a pure rigid impact sensation.

[0149] Postoperative biomechanical properties: The device of this invention is a flexible fixation system. The elastic coating effectively absorbs the interface micro-movements and vibrations generated by daily activities (such as walking), while the six radial expansion flaps 213 structure at the end of the sleeve body 22 form an "expansion cage" type stable anchor in the cancellous bone, which has significant beneficial effects on promoting secondary bone healing and preventing stress shielding bone atrophy.

[0150] This invention provides a stable and easy-to-use bone plate fastening screw and its application method. It changes the traditional screw method, which relies passively on the friction between the threads and the bone for fastening. This invention uses an active expansion flap to create an active mechanical interlock, resulting in more stable and reliable fixation. Furthermore, the system's embedded elastic elements, such as coatings, materials, and radial expansion flaps, absorb micro-movements, transforming harmful friction into beneficial elastic deformation and creating an ideal mechanical environment that promotes secondary bone healing. This invention employs a non-threaded flexible connection structure, without any threads. A lifting unit connects the bone plate fittings and bone-side fixation components into a single unit, completing the fixation of the bone plate to the bone. The flexible connection structure of the lifting unit is connected to the radial expansion part of the bone-side fixation component, which expands the radial expansion part and fits tightly against the inner wall of the bone. This not only avoids rigid contact but also ensures a stable and reliable connection without relative displacement wear. The outer wall of the bone-side fixation component can produce a slight radial expansion and contraction with bone deformation. The radial expansion flap structure at the end can adapt to the axial deformation of the bone, and the slight sliding of the reverse teeth of the bone plate mating component can absorb lateral displacement. The three work together to achieve flexible adaptation. There is no relative displacement between the bone plate and the bone during limb movement, avoiding the wear problem of threaded / rigid structures in the prior art.

[0151] This invention achieves an elastic fit between the sleeve body and the bone, and the bone plate mating component is bonded to the bone plate through an elastic coating, both avoiding rigid contact. The one-way locking part of the bone plate mating component and the locking engagement structure of the lifting unit allow for slight displacement with no thread wear, reducing friction debris and solving complications such as inflammation and foreign body reactions caused by debris in existing technologies. Moreover, the anchoring effect formed by the radial expansion flap on the bone side fixation component has a pull-out resistance far superior to that of traditional screws in osteoporotic bones. The circumferentially uniform distribution of multiple flaps also provides extremely strong anti-rotational stability. The elastic expansion of the sleeve body exerts uniform compressive force on the bone (pressure ≤5MPa), solving the problem of bone fracture caused by threaded insertion in existing technologies. The large-area conical contact between the bone plate mating component 1 and the bone plate 4, and the extensive contact between the flap and the bone, all ensure uniform stress distribution, greatly reducing the risk of complications such as bone plate fracture and screw (sleeve) cutout.

[0152] Furthermore, this invention abandons the traditional rigid threaded locking method, achieving anchoring through the lifting unit 3 driving the radial expansion part 21, and locking through the one-way locking part 11; there are no rigid friction pairs such as threads that continuously slide relative to each other, thus eliminating the possibility of metal or polymer debris generated by friction from a mechanical structural principle. Moreover, the fixation system of this invention has multi-level flexibility: 1) Radial flexibility: the radial expansion flap of the bone-side fixation member 2 can elastically expand and contract with the radial deformation of the bone hole wall; 2) Interface flexibility: the elastic coating or low-modulus material body on the assembly surface of the bone plate mating member 1 can absorb the axial micro-movement between the bone plate and the bone; 3) Locking flexibility: the surface contact engagement between the wedge and the rack allows for a small amount of elastic slippage. Through the synergy of these three aspects, the fixation system can conform to the physiological micro-movement of the bone, transforming it into a mechanical environment conducive to bone healing rather than a destructive force that leads to loosening and inflammation.

[0153] This invention improves surgical operability and fixation reliability. 1) Simplified operation: The surgeon only needs to perform a single lifting action to simultaneously complete bone anchoring, bone plate clamping, and system locking, significantly improving surgical efficiency; 2) The virtual coplanar design of the wedge top ensures that multiple teeth are simultaneously and evenly stressed; its large-area planar contact with the rack ensures uniform stress distribution, excellent fatigue resistance, and stepless adjustment and stable maintenance of locking tension; 3) The shallow thread and tool interface design at the proximal end of the bone-side fixation member enables convenient and stable pre-positioning, laying the foundation for subsequent expansion anchoring.

[0154] In the description of this invention, it should be understood that terms such as “length”, “width”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, and “outer” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0155] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0156] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A bone plate fastening screw, comprising a bone plate mating component and a bone side fixation component, characterized in that, A lifting unit is connected between the bone plate fitting and the bone side fixation component; The bone plate fitting is provided with an axial through hole for the lifting unit to pass through, and a one-way locking part is provided on the hole wall of the axial through hole. The bone-side fixation member is a hollow tubular structure, and the bone-side fixation member includes a radially expanded portion; The lifting unit is axially movable and passes through the inner circumference of the bone plate fitting and the bone side fixation member. The lifting unit includes a flexible connecting structure at the distal end and a locking fitting structure at the proximal end. The flexible connecting structure engages with the radial expansion portion, and the locking fitting structure engages with the one-way locking portion. By lifting the lifting unit proximally, the radial expansion portion can be synchronously driven to expand to anchor to the bone, and the locking fitting structure can be engaged with the one-way locking portion, thereby securing the bone plate to the bone.

2. The bone plate fastening screw according to claim 1, characterized in that, The bone plate fitting includes a main body, the interior of which is provided with an axial through hole, and the one-way locking part protrudes from the hole wall of the axial through hole for fitting and engaging with the locking structure of the lifting unit. The one-way locking part includes at least one wedge-type locking unit, which extends axially along the axial through hole, and the wedge-type locking unit includes a plurality of protruding wedges that are continuously distributed axially along the axial through hole.

3. The bone plate fastening screw according to claim 2, characterized in that, The number of wedge-type locking units is 1 to 6. When the number of wedge-type locking units is greater than 1, the wedge-type locking units are evenly distributed circumferentially along the axial through hole. The protruding tops of the wedges are all located on the same plane, and the plane is perpendicular to the axis of the axial through hole. The cross-sectional shape of the wedge perpendicular to its extension direction is triangular or trapezoidal. Preferably, the wedge includes a locking surface and a guide ramp, wherein the locking angle α of the locking surface satisfies: 0° < α ≤ 20°; the guide angle β of the guide ramp satisfies: 20° ≤ β ≤ 40°; and β – α > 5°; Preferably, in each of the wedge-type locking units, the locking surfaces of all the wedges are parallel to each other and are configured to engage simultaneously with the locking engagement structure of the lifting unit.

4. The bone plate fastening screw according to claim 2, characterized in that, The one-way locking part is connected to the main body part through an elastic beam. The axial length of the elastic beam is less than the axial length of the one-way locking part. The one-way locking part can generate radial elastic deformation through the elastic beam.

5. A bone plate fastening screw according to claim 2, characterized in that, The main body is made of a biocompatible polymer material, and the elastic modulus of the polymer material is lower than that of titanium alloy. Preferably, the polymeric material includes polyetheretherketone or polyphenylene ether nitrile ketone; Preferably, the outer side of the end of the main body is provided with a mounting surface that mates with the fixing hole of the bone plate. The mounting surface is a conical surface or a spherical curved surface. When the mounting surface is a conical surface, its taper ratio is 1:5 to 1:

10. Preferably, the mounting surface is provided with an elastic damping coating for absorbing micro-motion energy.

6. The bone plate fastening screw according to claim 1, characterized in that, The bone-side fixation member includes a sleeve body, and the radial expansion portion is disposed at the first end of the sleeve body. The radial expansion portion includes a radial expansion structure, and the radial expansion structure is connected to the flexible connection structure of the lifting unit. The radial expansion portion includes an axial groove disposed along the axial direction of the sleeve body, the length of the axial groove being less than the length of the sleeve body, and the radial expansion structure being a radial expansion lobe formed by dividing the axial groove, the radial expansion lobe being capable of radial expansion; Preferably, the number of axial grooves is 2-9, and the plurality of axial grooves are evenly distributed along the circumference of the sleeve body; Preferably, the skeletal fixation device is made of a biodegradable material, which includes at least one of polylactic acid, polyglycolic acid, polylactic-co-glycolic acid copolymer, chitosan, silk protein, or magnesium alloy.

7. The bone plate fastening screw according to claim 6, characterized in that, The outer circumference of the sleeve body is provided with an outer wall thread, the thread depth of which is 0.3-0.8mm and the pitch is 1.5-2.2mm. The outer wall thread is used to provide initial anti-rotation capability before final lifting and anchoring. Preferably, the bone plate fitting is provided with a mounting part, the mounting part is provided with an inner polygonal hole, the corresponding end of the bone side fixation member is provided with a mounting fitting part, and the mounting fitting part is provided with an outer polygonal shaft segment; The diameter of the inscribed circle of the inner polygonal hole is larger than the diameter of the circumscribed circle of the outer polygonal shaft segment; The bottom end face of the inner polygonal hole is an axial abutment surface, which can abut against the end face of the outer polygonal shaft segment.

8. A bone plate fastening screw according to any one of claims 1-7, characterized in that, The lifting unit includes a flexible connecting structure at a first end, a locking engagement structure at a second end, and an intermediate connecting structure connecting the flexible connecting structure and the locking engagement structure. The flexible connection structure includes a conical structure, the outer periphery of which is provided with a conical surface, the conical surface being connected to the radial expansion portion, for pressing against and expanding the radial expansion portion during axial movement; The locking engagement structure includes a linear groove unit, which includes a plurality of continuously and evenly distributed linear grooves arranged along the axial direction. The linear grooves are used to engage with the one-way locking part to achieve one-way locking. Preferably, the distal inner side of the bone-side fixation member is provided with a limiting protrusion, and the distal end of the lifting unit is provided with a limiting structure that cooperates with the limiting protrusion; the limiting protrusion and the limiting structure cooperate to prevent the lifting unit from accidentally dislodging from the distal end after it is fully inserted into the bone-side fixation member.

9. A bone plate fastening screw according to claim 8, characterized in that, The lifting unit is a solid rod structure integrally machined, and the cross-section of the lifting unit is a regular shape; The linear groove unit is arranged along the axial direction of the lifting unit, and the axial length of the linear groove unit is greater than the axial length of the one-way locking part. The bearing surface of the linear groove and the locking surface of the one-way locking part are a planar contact fit structure that fits each other.

10. A method of using a bone plate fastening screw as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Insert the bone fixation piece into the pre-drilled bone through hole. S2. Align the fixation holes of the bone plate with the implanted bone fixation device, and then place the bone plate fitting into the fixation holes of the bone plate to initially position it. S3. The lifting unit is positioned with one end having a locking mechanism on the outside and the other end having a flexible connection mechanism on the inside. The lifting unit is pre-fixed to the bone-side fixation member. The inside of the lifting unit is passed through the hollow interior of the bone-side fixation member until the flexible connection mechanism is fully inserted into the radial expansion portion of the bone-side fixation member. The lifting unit and the bone-side fixation member are then simultaneously inserted into the bone through hole. S4. Clamp the outer end of the lifting unit, and then apply a continuous pulling force to make the flexible connection structure of the lifting unit press against the radial expansion part, causing it to expand radially and press against the bone hole wall; while the locking fit structure of the lifting unit contacts the one-way locking part of the bone plate fitment, and they mesh with each other to achieve axial locking. S5. Control the lifting force according to usage requirements to achieve preset tension and automatic locking.

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