Bone nail capable of loading coating and coating mold thereof
By designing load-coated bone nails and coating molds, the problems of bone nonunion and femoral head necrosis in the treatment of femoral neck fractures in the prior art are solved, and the strong internal fixation and bone repair of the fracture are achieved, and the healing rate is improved. and reduce necrosis rate and ensure stable and convenient removal of bone nails.
Patent Information
- Application Number
- CN202411278379.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-12
- Publication Date
- 2024-12-06
AI Technical Summary
In the prior art, when treating femoral neck fractures, closed reduction hollow pressurized screw internal fixation surgery is difficult to achieve strong internal fixation of the fracture and precise implantation of bone repair materials at the same time, resulting in postoperative nonunion and femoral head necrosis.
A load-coated bone nail is designed, including two parts: the bone nail body and the coating. The bone nail body is a semi-thread hollow pressurized nail, and is equipped with a hollow channel and a reverse self-tapping section. The coating section is used for loading. Bone repair material, combined with coating mold, facilitates the production and application of bioactive coatings, ensuring the structural strength and operational convenience of bone nails.
It realizes the strong internal fixation of fractures and the precise implantation of bone repair materials without increasing trauma and prolonging the surgical time, which improves the postoperative fracture healing rate and reduces the femoral head necrosis rate, and the bone nails are healed after healing. Can be taken out smoothly.
Smart Images
Figure CN119074190A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of orthopedic medical devices, and more specifically relates to a bone nail capable of bearing a coating and a coating mold thereof. Background Art
[0002] Femoral neck fractures are very common in clinical practice. Young and middle-aged patients with femoral neck fractures and some elderly patients with femoral neck fractures require internal fixation treatment. Among them, closed reduction and hollow compression screw internal fixation is the most widely used because of its low trauma, simple operation, and the ability to change the configuration or number of bone screws according to needs.
[0003] A large number of studies have shown that good reduction, reliable internal fixation, and minimal surgical injury are important guarantees for a good prognosis of femoral neck fractures. Although closed reduction and hollow compression screw internal fixation have the above characteristics, there is still a high probability of nonunion and femoral head necrosis after surgery. During open reduction and internal fixation, some scholars use several internal fixation devices for combined fixation, implant materials that promote bone repair at the fracture end, and even use vascularized bone flap transplantation to promote bone healing and reduce the risk of femoral head necrosis. However, there are disadvantages such as long operation time, heavy bleeding, and large trauma, and the problem of postoperative nonunion and femoral head necrosis has not been completely solved. Although implanting bone repair materials at the fracture end is one of the effective methods to promote bone healing, closed reduction and hollow compression screw internal fixation does not expose the femoral neck fracture end, the incision is extremely small and far from the fracture end, and it is very difficult to accurately implant bone repair materials at the fracture end.
[0004] If hollow compression screws can be loaded with materials that promote bone repair, the closed reduction and hollow compression screw internal fixation of femoral neck fractures can simultaneously complete the strong internal fixation of the fracture and the precise implantation of bone repair materials, thereby improving the treatment effect without increasing trauma or prolonging the operation time. However, the currently commonly used hollow compression screws in clinical practice are difficult to effectively load bone repair materials.
[0005] Therefore, some scholars have adopted the design of opening side holes on hollow screws, and perfusing bioactive materials that can promote bone healing through the hollow tubes, allowing them to diffuse to the outside through the side holes to achieve the purpose of promoting bone healing. However, the setting of side holes reduces the structural strength of the bone screws, and when the bone screws are locked into the bones, they are prone to breakage due to excessive shear force; and bone growth into the side holes will increase the difficulty of removing the bone screws. Summary of the invention
[0006] In view of this, the present invention provides a bone nail capable of loading a coating and a coating mold thereof, which are used to treat femoral neck fractures, aiming to solve problems such as postoperative nonunion and femoral head necrosis. The nail has the advantages of high structural strength, convenient operation, stable bone setting and the ability to load bone repair materials.
[0007] In order to achieve the above object, the present invention adopts the following technical solution:
[0008] A bone screw capable of carrying a coating, comprising a bone screw body and a coating; the bone screw body is a semi-threaded hollow compression screw, and a hollow channel is arranged at the central axis of the bone screw body; the bone screw body is provided with a nail head, a front smooth rod, a transition section, a coating section, a reverse self-tapping section, a rear threaded rod and a tip self-tapping section in sequence from top to bottom; the thread minor diameter of the front smooth rod is the same as that of the rear threaded rod; the transition section is a region where the front smooth rod transitions to the coating section, and the outer diameter gradually decreases to reduce stress concentration; the outer diameter of the coating section is smaller than the outer diameter of the front smooth rod, and is used to carry a coating made of bone repair active material; a reverse self-tapping tooth mouth is arranged at the upper end of the reverse self-tapping section for removing the bone screw after bone healing; the tip self-tapping section is arranged at the lower end of the bone screw body, and a positive self-tapping tooth mouth is arranged at the end to ensure that the bone screw self-taps into the bone.
[0009] Furthermore, the outer diameter of the nail head is larger than the major diameter of the thread of the rear threaded rod; a hexagon socket joint is provided on the countersunk head at the upper end of the nail head, and a positioning pin guide slope is provided inside the nail head below the hexagon socket joint, connecting the hexagon socket joint and the hollow channel.
[0010] Furthermore, an upper annular inclined surface with an angle of 30° with the vertical surface where the central axis of the bone screw body is located is provided on one side of the reverse self-tapping section close to the coating section; a plurality of groups of upper reverse vertical surfaces and upward slope surfaces are provided on the outer surface of the reverse self-tapping section in the circumferential direction; each group of upper reverse vertical surfaces and upward slope surfaces, together with the upper annular inclined surface, constitute a reverse self-tapping tooth mouth for reverse cutting of bone.
[0011] Furthermore, the angle between the extended line of the line connecting the projection point of the intersection line of the upper reverse vertical surface and the minor diameter surface of the threaded rod at the rear section on the horizontal plane and the projection point of the central axis of the bone screw body on the horizontal plane and the projection line of the upper reverse vertical surface on the horizontal plane is 15°; the angle between the upward slope surface and the vertical plane where the central axis of the bone screw body is located is 30°.
[0012] Furthermore, the thread of the rear threaded rod starts from the lower end of the bone screw body; the thread height of the last circle at the upper end of the rear threaded rod gradually decreases to be flush with the surface of the minor diameter of the thread of the rear threaded rod; the last two circles of thread at the upper end of the rear threaded rod are provided with a cutting edge whose opening direction is consistent with the thread direction.
[0013] Furthermore, the lower end surface of the bone screw body is a horizontal surface, forming a lower top surface; the side wall of the hollow channel is obliquely cut upward to the outside to form a bottom inclined surface (18), and the angle between the bottom inclined surface (18) and the lower top surface (19) is 20°; the tip self-tapping section is provided with a plurality of groups of lower inclined surfaces, lower slope surfaces and lower positive vertical surfaces in the circumferential direction on the outer surface; the lower inclined surfaces, lower slope surfaces and lower positive vertical surfaces in each group, together with the lower top surface and the bottom inclined surface, constitute the positive self-tapping tooth mouth; the lower inclined surface is formed from the surface of the minor diameter of the threaded rod of the rear section toward the The hollow channel is beveled 30° downward to reduce the thickness of the tip tube wall; the downward slope surface connects the lower positive vertical surface and the lower bevel surface, and the angle between it and the horizontal plane is 60°, and it tends to cut a little tube wall into the hollow channel to form a notch; the extended line of the line between the projection point of the intersection of the lower positive vertical surface and the inner wall of the hollow channel on the horizontal plane and the projection point of the central axis of the bone screw body on the horizontal plane, and the projection line of the lower positive vertical surface on the horizontal plane, has an angle of 15°; the angle between the bottom bevel surface and the lower top surface is 20°.
[0014] A coating mold for a bone nail capable of bearing a coating, comprising a module A and a module B arranged relatively to each other, wherein the butt joint surfaces are both provided with a plurality of grooves with semicircular cross-sections; the diameter of the grooves is the same as the outer diameter of the front smooth rod, and the length is greater than the length of the coating segment; when the module A and the module B are butt jointed, the grooves correspond to synthetic circular holes; the coating segment is placed in the circular hole, and the gap between the coating segment and the grooves is filled with a bone repair material as a coating.
[0015] Furthermore, two limiting pins and two limiting holes are respectively arranged on both sides of the docking surface of the module A and the module B; the limiting pins correspond to the positions of the limiting holes, and the limiting pins are embedded in the limiting holes when the module A and the module B are docked.
[0016] Furthermore, two adjacent side surfaces of the short side of the docking surface of module A are provided with a snap base, and a curved snap is rotatably connected to the snap base; a cross bar at the upper end of the snap is arranged parallel to the groove; a plurality of fine horizontal lines are arranged on the opposite surface of the docking surface of module B, and the horizontal lines are arranged parallel to the groove; when module A is docked with module B, the cross bar at the upper end of the snap is frictionally matched with the horizontal lines.
[0017] The beneficial effects of the present invention are:
[0018] The bone screw of the present invention has space and ability to load bone repair active materials, and can be used to make coatings. Because the bone repair active materials used to make the coatings are mostly absorbable, the coatings will be replaced by new bone after bone healing, forming a "bone wall" that hinders the removal of the screws, making the position of the bone screw more stable, and the reverse self-tapping structure can ensure the smooth removal of the bone screws; the coating mold is a convenient tool for making coatings, and some bone tissue engineering technologies can be used to make fast-curing sustained-release coatings with bone repair activity, which can achieve "made-to-use" coatings during surgery. When closed reduction hollow pressurized screw internal fixation is used to treat femoral neck fractures, strong internal fixation of fractures and precise implantation of bone repair materials can be completed simultaneously, taking into account the advantages of minimally invasive, rapid, efficient and convenient, and achieving the purpose of improving postoperative fracture healing rate and reducing postoperative femoral head necrosis rate. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.
[0020] Figure 1 It is a schematic diagram of the overall structure of the bone screw of the present invention.
[0021] Figure 2 It is a top view of the bone screw of the present invention.
[0022] Figure 3 It is a cross-sectional view of the bone screw of the present invention.
[0023] Figure 4 for Figure 1 Middle AA section view.
[0024] Figure 5 It is a partial enlarged view of the reverse self-tapping section of the bone screw of the present invention.
[0025] Figure 6 It is a bottom view of the bone screw of the present invention.
[0026] Figure 7 It is a partial enlarged view of the tip self-tapping section of the bone screw of the present invention.
[0027] Figure 8 It is the front view of the A module in the coating mold of the present invention.
[0028] Fig. 9 It is a side view of a module in the coating mold of the present invention.
[0029] Fig.10 It is the front view of module B in the coating mold of the present invention.
[0030] Fig.11 This is the main view of the coating mold of the present invention after the A and B modules are connected.
[0031] Fig.12 It is a top view of the coating mold of the present invention after the A and B modules are docked.
[0032] Fig.13 This is a diagram showing the coating mold in use according to the present invention.
[0033] Fig.14 This is a diagram showing the use status of the bone screw capable of loading a coating according to the present invention.
[0034] Among them, in the figure:
[0035] 1-nail head; 2-front smooth rod; 3-transition section; 4-coated section; 5-reverse self-tapping section; 6-rear threaded section; 7-tip self-tapping section; 8-locating needle guide slope; 9-hexagon socket joint; 10-hollow channel; 11-upper reverse vertical surface; 12-blade edge; 13-upper annular slope; 14-upper slope surface; 15-lower slope surface; 16-lower slope surface; 17-lower reverse vertical surface; 18-bottom slope surface; 19-lower top surface; 20-groove; 21-round hole; 22-buckle base; 23-buckle; 24-limiting nail; 25-transverse line; 26-limiting hole; 27-gap; 28-fracture line. DETAILED DESCRIPTION
[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0037] It should be noted that when a component is referred to as being "fixed on" or "disposed on" another component, it may be directly or indirectly located on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The directions or positions indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the accompanying drawings and are only for the convenience of description and cannot be understood as limitations on the present technical solution. The terms "first" and "second" are only used for the convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Several" means two or more, unless otherwise clearly and specifically defined.
[0038] Please see attached Figure 1-7The present invention provides a bone screw capable of bearing a coating, comprising a bone screw body and a coating; the bone screw body is a semi-threaded hollow pressure screw, which is provided with a nail head 1, a front smooth rod 2, a transition section 3, a coating section 4, a reverse self-tapping section 5, a rear threaded rod 6 and a tip self-tapping section 7 in sequence from top to bottom.
[0039] The outer diameter of the nail head 1 is larger than the major diameter of the thread of the rear threaded rod 6, which can provide good pressurization performance and reduce the risk of the entire bone screw sinking into the femoral neck bone. The upper countersunk head of the nail head 1 is provided with a hexagon socket joint 9, and a positioning needle guide inclined surface 8 is provided inside the nail head 1 below the hexagon socket joint 9, connecting the hexagon socket joint 9 with the hollow channel 10 at the central axis of the bone screw body. When the positioning needle is inserted into the nail head 1 from above, it can quickly slide into the hollow channel 10.
[0040] The outer diameter of the front smooth rod 2 is the same as the thread minor diameter of the rear threaded rod 6, which can reduce the swing of the bone screw in the bone channel. The transition section 3 is an annular slope, which is the transition area from the front smooth rod 2 to the coating section 4, connecting the front smooth rod 2 and the coating section 4. The gradually decreasing outer diameter can disperse the stress concentration caused by the sudden decrease in diameter.
[0041] The coating section 4 is located between the transition section 3 and the reverse self-tapping section 5. The outer diameter of the coating section 4 is smaller than the outer diameter of the front smooth rod 2, and is used to load the coating made of bone repair active material; the surface of the coating section 4 is set to a rough surface, which can increase the adhesion stability of the coating; the coating thickness is the difference between the outer diameter radius of the coating section 4 and the front smooth rod 2.
[0042] The length and position of the coating segment 4 can be adjusted according to the total length of the bone nail to ensure that the coating segment 4 can span the fractured end of the femoral neck and simultaneously complete the strong internal fixation of the fracture and the precise implantation of the bone repair material.
[0043] The coating section 4 may also be constructed in other ways, for example, firstly making a porous hydroxyapatite scaffold in the coating section 4 and then filling it with a bioactive material that promotes bone repair.
[0044] The reverse self-tapping section 5 is provided with a reverse self-tapping thread opening at the upper end; the reverse self-tapping section 5 is provided with an upper annular inclined surface 13 with an angle of 30° with the vertical plane where the central axis of the bone screw body is located on the side close to the coating section 4, which can reduce the stress concentration caused by the diameter change and also reduce the resistance when the screw is removed. The reverse self-tapping section 5 is provided with multiple groups of upper reverse vertical surfaces 11 and upper slope surfaces 14 along the circumferential direction on the outer surface, and each group of upper reverse vertical surfaces 11 and upper slope surfaces 14, together with the upper annular inclined surface 13, constitutes a reverse self-tapping thread opening for reverse cutting of bone, ensuring smooth removal of the bone screw. The angle between the projection point of the intersection of the upper reverse vertical surface 11 and the threaded minor diameter surface of the rear section threaded rod 6 on the horizontal plane and the projection point of the central axis of the bone screw body on the horizontal plane is 15°; the angle between the upper slope surface 14 and the vertical plane where the central axis of the bone screw body is located is 30°. On each reverse self-tapping tooth, the connection line between the upper reverse vertical surface 11 and the upper annular inclined surface 13 and the connection line between the upper reverse vertical surface 11 and the surface of the screw form a cutting edge, so that the reverse self-tapping tooth can smoothly cut bone.
[0045] When the bioactive coating is replaced by new bone, a "bone wall" will be formed that hinders the removal of the bone screws. The reverse self-tapping teeth can cut the "bone wall" when removing the bone screws after the bone heals, allowing the bone screws to be removed smoothly after the bone heals.
[0046] The thread of the rear threaded rod 6 starts from the lower end of the bone screw body, with a tooth height of 1.25mm, a thread pitch of 3mm, and 7 turns of thread; the thread height of the last turn at the upper end of the rear threaded rod 6 gradually decreases to be flush with the surface of the thread minor diameter of the rear threaded rod 6, forming a strong bite with the bone, and cooperating with the nail head 1 to provide good pressurization performance; the last two turns at the upper end of the rear threaded rod 6 are provided with a cutting edge 12 with an opening direction consistent with the thread direction, which can cooperate with the reverse self-tapping thread to increase the ability to remove the bone screw after bone healing.
[0047] The tip self-tapping section 7 is arranged at the lower end of the bone screw body, which is modified from the lower part of the rear section threaded rod 6, and a positive self-tapping thread opening is arranged at the end; the lower end surface of the bone screw body is a horizontal plane, forming a lower top surface 19; a bottom inclined surface 18 is formed by obliquely cutting from the hollow channel 10 to the outside and upward; the angle between the bottom inclined surface 18 and the lower top surface 19 is 20°; the tip self-tapping section 7 is provided with a plurality of groups of lower inclined surfaces 15, lower slope surfaces 16 and lower positive vertical surfaces 17 along the circumferential direction on the outer surface; the lower inclined surfaces 15, lower slope surfaces 16 and lower positive vertical surfaces 17 in each group, together with the lower top surface 19 and the bottom inclined surface 18, constitute the positive self-tapping thread opening; the lower inclined surface 15 is obliquely cut 30° downward from the surface of the thread minor diameter of the rear section threaded rod 6 toward the hollow channel 10, and is used to reduce the thickness of the tip tube wall, and can reduce the tip wall thickness to about 0.5mm, which can significantly reduce the resistance encountered when the bone screw is screwed into the bone. The downslope surface 16 connects the lower positive vertical surface 17 and the lower inclined surface 15, and the angle between it and the horizontal plane is 60°, and it is inclined to cut a little tube wall into the hollow channel to form a notch; the angle between the projection point of the intersection line of the lower positive vertical surface 17 and the inner wall of the hollow channel 10 on the horizontal plane and the projection point of the central axis of the bone screw body on the horizontal plane and the projection line of the lower positive vertical surface 17 on the horizontal plane is 15°. In each positive self-tapping mouth, the connection line of the lower reverse vertical surface 17 and the lower inclined surface 15 forms a blade edge to ensure that the bone screw can be smoothly screwed into the bone.
[0048] Please refer to the attached Figure 8-13 The present invention provides a bone screw coating mold for assisting coating adhesion; the coating mold includes a module A and a module B, the two modules are arranged opposite to each other, and the butt joint surfaces are provided with a plurality of grooves 20 with a semicircular cross section, the diameter of which is the same as the outer diameter of the front smooth rod 2, and the length is greater than the length of the coating section 4; the surface of the groove 20 is smoothed. The module A is butt jointed with the module B so that the groove 20 corresponds to a synthetic circular hole 21, which can be closely matched with the outer surface of the front smooth rod 2; the coating section 4 is placed in the circular hole 21, and the gap 27 between the groove 20 and the coating section 4 is filled with bone repair material to form a coating, the surface of which is flat and flush with the outer surface of the front smooth rod 2.
[0049] Two limiting pins 24 and two limiting holes 26 are respectively arranged on both sides of the docking surface of the A module and the B module; the limiting pins 24 are adapted to the positions of the limiting holes 26, and the limiting pins 24 can be embedded in the limiting holes 26. After the A module and the B module are docked, the limiting pins 24 are embedded in the limiting holes 26, so that the grooves 20 on the two modules can be accurately docked to avoid the generation of gaps that affect the shape of the coating.
[0050] The two adjacent sides of the short side of the docking surface of the A module are provided with a buckle base 22, and the buckle base 22 is rotatably connected with a buckle 23 bent into a "J" shape; the upper end cross bar of the buckle 23 is arranged in parallel with the groove 20; and the opposite surface of the docking surface of the B module is provided with a number of fine horizontal stripes 25, and the horizontal stripes 25 are arranged in parallel with the groove 20. After the A module is docked with the B module, the buckle 23 rotates to turn the cross bar over the B module and frictionally cooperate with the horizontal stripes 25, so that the buckle 23 can fasten the B module from both sides to avoid accidental loosening, and can provide a pressurizing effect for the coating production, ensuring that the coating surface is flat and flush with the outer surface of the front smooth rod 2, thereby reducing the friction between the coating and the bone surface and preventing the coating from falling off. After pressurization, the bone repair material is solidified and dried, and then demoulding is performed to obtain a bone nail loaded with a bioactive coating.
[0051] The method for making the coated bone nail and the coating mold of the present invention is as follows: using a chitosan solution of a certain concentration, adding a certain amount of rhBMP-2 according to demand, fully stirring, adding it to the self-setting calcium phosphate bone cement in an appropriate proportion, and fully stirring again to form a dough-stage bone repair material; selecting a new bone nail of suitable length, and evenly coating the coating section 4 with the dough-stage bone repair material; Fig.13 As shown, a bone screw coated with bone repair material is placed inside the groove of module A, so that part of the front smooth rod 2, the entire coating section 4 and part of the reverse self-tapping section 5 are embedded in the groove 20, and the thread of the rear threaded rod 6 is prevented from being embedded in the groove 20, so that excess bone repair material can overflow along the reverse self-tapping teeth of the reverse self-tapping section 5; press both ends of the bone screw to make the front smooth rod 2 fit the groove 20, and remove excess bone repair material on both sides of the groove 20; cover module B and press; if the A and B molds cannot fit, it means that excess bone repair material has overflowed, remove the B mold and remove the excess bone repair material on both sides of the groove 20 again (this step may need to be repeated 1-2 times); cover module B, so that the limiting nail 24 is embedded in the limiting hole 26, and the buckle 23 is rotated to make it frictionally fit and buckle with the transverse pattern 25 to press and shape the bone screw and the repair material; demold after the coating is cured, and the resulting coating has good biocompatibility, absorbability, sustained release, and the function of promoting bone repair.
[0052] Please see attached Fig.14 When the bone screw capable of loading the coating of the present invention is used, the conventional steps of closed reduction hollow compression screw internal fixation of femoral neck fracture are followed. After the proximal lateral cortex of the femur is opened along the positioning needle, the bone screw loaded with the coating is screwed into the bone, so that the coating segment 4 crosses the fracture line 28 to connect the two bone segments; after the bone heals, the coating will be replaced by new bone to form a "bone wall" that hinders the removal of the bone screw; when the bone screw is removed, the bone screw is rotated in the opposite direction, and the new "bone wall" is broken by the reverse self-tapping structure, so that the bone screw can be removed smoothly and a smaller wound can be ensured.
[0053] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.
[0054] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A bone screw capable of bearing a coating, characterized in that: The bone screw body comprises a bone screw body and a coating; the bone screw body is a semi-threaded hollow pressure screw, and a hollow channel (10) is arranged at the central axis of the bone screw body; the bone screw body is provided with a nail head (1), a front smooth rod (2), a transition section (3), a coating section (4), a reverse self-tapping section (5), a rear threaded rod (6) and a tip self-tapping section (7) in sequence from top to bottom; The thread diameters of the front smooth rod (2) and the rear threaded rod (6) are the same; the transition section (3) is the transition area from the front smooth rod (2) to the coating section (4), and the outer diameter gradually decreases to reduce stress concentration; the outer diameter of the coating section (4) is smaller than the outer diameter of the front smooth rod (2), and is used to load the coating made of bone repair active material; the upper end of the reverse self-tapping section (5) is provided with a reverse self-tapping tooth mouth for removing the bone screw after bone healing; the tip self-tapping section (7) is provided at the lower end of the bone screw body, and the end is provided with a positive self-tapping tooth mouth to ensure that the bone screw self-taps into the bone.
2. A bone screw capable of bearing a coating according to claim 1, characterized in that: The outer diameter of the nail head (1) is larger than the major diameter of the thread of the rear threaded rod (6); a hexagon socket joint (9) is provided on the countersunk head at the upper end of the nail head (1); a positioning pin guide inclined surface (8) is provided inside the nail head (1) below the hexagon socket joint (9) to connect the hexagon socket joint (9) and the hollow channel (10).
3. The bone screw capable of bearing a coating according to claim 1, characterized in that: An upper annular inclined surface (13) having an angle of 30° with the vertical surface where the central axis of the bone screw body is located is arranged on the side of the reverse self-tapping section (5) close to the coating section (4); a plurality of groups of upper reverse vertical surfaces (11) and upward slope surfaces (14) are arranged on the outer surface of the reverse self-tapping section (5) along the circumferential direction; each group of upper reverse vertical surfaces (11) and upward slope surfaces (14), together with the upper annular inclined surface (13), constitutes a reverse self-tapping tooth mouth for reverse cutting of bone.
4. A bone screw capable of bearing a coating according to claim 3, characterized in that: The angle between the projection point of the intersection of the upper reverse vertical surface (11) and the minor diameter surface of the thread of the rear threaded rod (6) on the horizontal plane and the projection point of the central axis of the bone screw body on the horizontal plane and the extended line of the line connecting the projection line of the upper reverse vertical surface (11) on the horizontal plane is 15°; the angle between the upward slope surface (14) and the vertical plane where the central axis of the bone screw body is located is 30°.
5. The bone screw capable of bearing a coating according to claim 1, characterized in that: The thread of the rear threaded rod (6) starts from the lower end of the bone screw body; the thread height of the last circle of the upper end of the rear threaded rod (6) gradually decreases to be flush with the surface of the thread diameter of the rear threaded rod (6); the last two circles of the thread at the upper end of the rear threaded rod (6) are provided with a cutting edge (12) whose opening direction is consistent with the thread direction.
6. The bone screw capable of bearing a coating according to claim 1, characterized in that: The lower end surface of the bone screw body is a horizontal surface, forming a lower top surface (19); a bottom inclined surface (18) is formed by obliquely cutting from the side wall of the hollow channel (10) to the outside and upward, and the angle between the bottom inclined surface (18) and the lower top surface (19) is 20 degrees; the tip self-tapping section (7) is provided with a plurality of groups of lower inclined surfaces (15), lower slope surfaces (16) and lower positive vertical surfaces (17) along the circumferential direction on the outer surface; the lower inclined surfaces (15), lower slope surfaces (16) and lower positive vertical surfaces (17) in each group, together with the lower top surface (19) and the bottom inclined surface (18), constitute the positive self-tapping tooth opening; the lower inclined surface (15) is formed from the The surface of the threaded minor diameter of the rear threaded rod (6) is inclined 30° downward toward the hollow channel (10) to reduce the thickness of the tip tube wall; the downward slope (16) connects the lower positive vertical surface (17) and the lower inclined surface (15), and the angle between it and the horizontal plane is 60°, and it is inclined to cut a small amount of the tube wall in the hollow channel to form a notch; the angle between the projection point of the intersection of the lower positive vertical surface (17) and the inner wall of the hollow channel (10) on the horizontal plane and the extended line of the line connecting the projection point of the central axis of the bone screw body on the horizontal plane and the projection line of the lower positive vertical surface (17) on the horizontal plane is 15°.
7. A coating mold for a bone nail capable of bearing a coating according to any one of claims 1 to 6, characterized in that: The invention comprises a module A and a module B which are arranged opposite to each other, and the butt joint surfaces are both provided with a plurality of grooves (20) with a semicircular cross section; the diameter of the groove (20) is the same as the outer diameter of the front smooth rod (2), and the length is greater than the length of the coating section (4); when the module A and the module B are butt jointed, the groove (20) corresponds to a synthetic circular hole (21); the coating section (4) is placed in the circular hole (21), and the gap (27) between the coating section (4) and the groove (20) is filled with a bone repair material as a coating.
8. The coating mold for a bone nail capable of bearing a coating according to claim 7, characterized in that: Two limiting pins (24) and two limiting holes (26) are respectively arranged on both sides of the docking surface of the module A and the module B; the limiting pins (24) correspond to the positions of the limiting holes (26), and when the module A and the module B are docked, the limiting pins (24) are embedded in the limiting holes (26).
9. The coating mold for a bone nail capable of bearing a coating according to claim 7, characterized in that: The two adjacent side surfaces of the short side of the docking surface of the A module are provided with a buckle base (22), and a curved buckle (23) is rotatably connected to the buckle base (22); the upper end cross bar of the buckle (23) is arranged parallel to the groove (20); the opposite surface of the docking surface of the B module is provided with a plurality of fine horizontal stripes (25), and the horizontal stripes (25) are arranged parallel to the groove (20); when the A module is docked with the B module, the upper end cross bar of the buckle (23) and the horizontal stripes (25) are frictionally matched.