Absorbable orthopedic implant and preparation method thereof

Abstract

The present invention provides an absorbable orthopedic implant and a preparation method thereof. The absorbable orthopedic implant comprises a multi-layer gradient structure: a core body, a first set of braided structures, and a second set of braided structures. The core body is an inner layer structure formed by polyester / or unidirectional / multidirectional continuous fiber pre-impregnated resin composite wire material / or sheet material; the first set of braided structures is sleeved on the outside of the core body, and continuous fiber pre-impregnated resin composite wire material / or tape material is used to form a mesh body through weaving / or winding; the second set of braided structures is sleeved on the outside of the first set of braided structures, and polyester sheets / or wires are used to form a preform through winding / or weaving; wherein, the first set of braided structures is at least one, and at least the outermost first set of braided structures is covered with the second set of braided structures. The absorbable orthopedic implant of the present invention has excellent mechanical properties, and the degradation rate can be adjusted, and there is no implant failure and late adverse reaction phenomenon.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of medical devices, and in particular to an absorbable orthopedic implant and a preparation method thereof. Background Art

[0002] In the medical field, orthopedic implants, such as bone screws, are mostly made of metal materials and their alloys, such as titanium alloys and stainless steel. Metal bone screws can promote bone healing and exhibit excellent mechanical properties such as high strength and good toughness, but they also have obvious defects: 1) The stiffness of metal materials is much higher than that of human bones, resulting in a stress shielding effect, and according to Wolff's law, there is a risk of bone degeneration; 2) Metal materials may release toxic metal ions and microparticles under physiological corrosion and wear, causing tissue inflammatory reactions; 3) Metal materials will block radiation therapy in cancer cases; 4) Metal materials (such as stainless steel, cobalt chromium, etc.) may cause biocompatibility issues related to corrosion and sensitization reactions; 5) Metal materials are radiopaque, and artifacts exist in CT and MRI, limiting the observation of the healing process; 6) The material is non-degradable, and the patient needs to undergo a secondary surgery to remove it after recovery, which is painful, and the cavity left after the bone screw is removed also has the risk of fracture. Therefore, non-metallic implants made of lighter and softer materials that still have sufficient strength to bear the load are a better choice.

[0003] Polymers and their composite materials are also commonly used to manufacture medical implants. Patent CN105167830B discloses a composite implant, which includes a threaded bone fixation screw made of carbon fiber composite polyetheretherketone (PEEK), including a core and a threaded connection layer. The core includes relatively straight and elongated fibers in a polymer matrix; the threaded connection layer includes fibers wound at a pitch matching the threaded connection of the screw. Some scholars have found through clinical experiments that carbon fiber reinforced PEEK right distal palm fracture surgery caused erosive tendon synovitis, accompanied by tendon stump decay, mainly due to the black carbon fiber being swallowed into multinucleated giant cells. Carbon fiber is used as an implant in clinical practice and there is a risk of causing acute or chronic inflammatory reactions, and because the material used is not bioabsorbable, it still requires secondary surgery to remove it or replace it due to the life of the implant itself during clinical application.

[0004] At present, absorbable polymers and their composite materials have been used to manufacture absorbable implants. Commonly used absorbable polymers, bioactive glass particles, hydroxyapatite powder, glass fiber and other reinforced absorbable polymer composite materials are mostly prepared by injection molding or 3D printing, and the glass fibers are mostly chopped glass fibers. The strength and stiffness of these composite materials are mostly lower than cortical bone, and their performance decays rapidly after degradation in the body, and they cannot meet the performance requirements of implants in load-bearing parts. Therefore, continuous fiber reinforced polymer composites have great application prospects in the field of medical implant products due to their performance advantages and absorbable characteristics, such as:

[0005] Patent CN107106210A discloses a medical implant comprising a plurality of layers, each layer comprising a polymer and a plurality of continuous reinforcing fibers. The patent relates to a threaded implant, wherein two complete composite material layers are wrapped around a tube using a hot air blower so that the layers adhere to each other and form a two-layer biocomposite tube, the biocomposite tube is cut into two thin sheets, and the thin sheets are pressed against each other using a hot steel block.

[0006] Patent CN112675365A discloses a method for preparing high-strength absorbable bone nails. Modified glass fibers are pulled and immersed in a polylactic acid organic mixed solution, dried to obtain a polylactic acid film, and stacked to obtain a plate; the plate is immersed in a polylactic acid organic mixed solution, and the bone nail is obtained after cleaning and cutting.

[0007] However, the above method introduces an organic solution during the preparation process, and it is impossible to determine whether the organic solution will remain in the polylactic acid film after drying, which poses certain risks; the bone nail structure is obtained by cutting, and the fibers in the cut section are exposed. After the bone nail is implanted in the human body, the exposed fibers serve as a fast channel for the capillary action of body fluids, which destroys the interface between the fibers and the polylactic acid matrix in a short time, causing a significant attenuation of the mechanical properties of the bone nail, and there is a certain risk in its safe use during fracture healing; in addition, the entire preparation process is manual, and human factors have a greater impact on the quality stability of the product, and it is impossible to achieve industrial mass production, which has certain limitations. Summary of the invention

[0008] The invention provides an absorbable orthopedic implant which is absorbable in the human body, has simple process and good material performance, and a preparation method thereof.

[0009] In order to solve the above technical problems, an embodiment of the present invention provides an absorbable orthopedic implant, comprising:

[0010] The core body is an inner layer structure formed by polyester / or unidirectional / multidirectional continuous fiber pre-impregnated resin composite wire material / or sheet material, and the composite wire material is made by a specific process;

[0011] The first braided structure is sleeved on the outside of the core body and is formed by weaving or winding continuous fiber pre-impregnated resin composite wire or tape to form a mesh;

[0012] The second braided structure is sleeved on the outside of the first braided structure and is made of polyester sheets and / or wires to form a preform by winding and / or weaving;

[0013] The preform is subjected to heat shaping, cutting and molding treatment to obtain an orthopedic implant; wherein, the number of inner layer structures is 0-n, n is a positive integer, the number of the first set of braided structures is at least 1, and at least the outermost first set of braided structures is covered with the second set of braided structures.

[0014] In some embodiments, the core is prepared by a continuous fiber and polyester material composite through a melt impregnation pultrusion process / or a melt impregnation pultrusion sheet layer stacking process, and the composite material ratio can be designed according to mechanical requirements, the core fiber mass fraction is between 0-95%, and the core diameter or / length and width should be ≥0.1mm;

[0015] In some embodiments, the first braided structure is woven with continuous fiber pre-impregnated resin composite wires, or wound with continuous fiber pre-impregnated resin composite tapes, and the fiber mass fraction of the wires / tapes is between 0-95%.

[0016] In some embodiments, the second braided structure is made of polyester sheets and / or wires and is formed into a preform by winding and / or weaving.

[0017] In some embodiments, the core includes but is not limited to a solid core and / or a hollow core.

[0018] In some embodiments, the reinforcing fibers in the continuous fiber pre-impregnated resin composite material wire and / or tape include but are not limited to carbon fiber, glass fiber, basalt fiber, etc., and the fiber content is between 0% and 90%; the linear density of the continuous fiber is any value or combination within 20tex-2400tex, and the continuous fiber pre-impregnated resin composite material wire and / or tape is a first set of braided structures, which is arranged on the outside of the core body by weaving and / or winding to achieve tight weaving or winding, and the porosity range is between 0-80%.

[0019] In some embodiments, the second braided structure is composed of polyester sheets and / or filaments, which can be homopolymers, copolymers or blends, formed by one or more polymers, wherein the bioabsorbable polyester can be a natural material or a synthetic material, including but not limited to, the bioabsorbable polyester includes but is not limited to polylactide (PLA), poly-L-lactide (PLLA), poly-DL-lactide (PDLLA) polyglycolide (PGA), polylactide glycolic acid (PLGA), polycaprolactone (PCL), poly(L-lactide-co-caprolactone) (PLLA-PCL) and combinations thereof, and the polyester sheets and / or filaments are the second braided structure, which is arranged outside the first braided structure by winding and / or weaving.

[0020] In some embodiments, the diameter of the absorbable orthopedic implant formed by the core, the first set of braided structures, and the second set of braided structures is not less than 0.3 mm, and can be customized to a larger size as needed (for practical applications and optimization considerations, the recommended diameter range is maintained at 0.3 mm-20 mm); the length is not less than 6 mm, and can be extended to a longer size as needed.

[0021] In some embodiments, the absorbable orthopedic implant is formed by a preform formed by an initial core, a first set of braided structures, and a second set of braided structures, which is subjected to heat shaping, cutting, and molding. The diameter of the preform is positively correlated with the diameter of the implant, and the inner core structure can be 0.

[0022] Another embodiment of the present invention also provides a method for preparing an absorbable orthopedic implant, which comprises:

[0023] Obtaining materials for preparing a core body, a first set of braided structures, and a second set of braided structures, wherein the materials for preparing the core body include composite wires, the materials for preparing the first set of braided structures include continuous fiber pre-impregnated resin composite wires / or tapes, and the materials for preparing the second set of braided structures include polyester sheets / or wires;

[0024] Preparing a core inner layer structure based on the polyester / or unidirectional / multidirectional continuous fiber pre-impregnated resin composite wire material / or sheet material;

[0025] Based on the continuous fiber pre-impregnated resin composite wire material / or tape, a first set of braided structures is formed by weaving / or winding outside the core; based on the polyester / or composite sheet / or wire material, a second set of braided structures is formed by winding / or weaving outside the first set of braided structures to form a preform;

[0026] The preform is heated, shaped, cut and molded to obtain an absorbable orthopedic implant.

[0027] In some embodiments, the continuous fiber pre-impregnated resin composite wire material / or tape is braided / or wound outside the core to form a first braided structure, including:

[0028] The continuous fiber pre-impregnated resin composite material wire material or tape is installed on a weaving spindle or a winding turntable, and the spindle or the turntable is controlled to run according to a preset track, so that the continuous fiber pre-impregnated resin composite material wire material or tape can be pressed and woven or wound at an angle on the surface of the core body to form one or more layers of the first braided structure;

[0029] Based on the polyester sheet material / wire material, a second braided structure is formed by winding / or weaving outside the first braided structure to form a preform, including: obtaining polyester pellets, and melt-extruding / calendering / or forming the polyester pellets to form a uniform sheet material / wire material. The sheet material / wire material and the first braided structure are mounted on the braiding spindle / or winding turntable, and the spindle / or turntable is controlled to run according to a preset track, so that the resin sheet material / wire material can be formed outside the first braided structure in a one-pressing and one-weaving / or angled winding manner to form a preform of the implant.

[0030] In some embodiments, the preform is subjected to heating, shaping, cutting, and molding to obtain an absorbable orthopedic implant, including:

[0031] The preform is heated to a target temperature, wherein the temperature parameters of the heating zone are set within a temperature range of 170° C. to 300° C.;

[0032] The heated preform is pressed and cooled by two grooved rollers arranged opposite to each other to obtain a profile preform with a regular cross section, sufficient fiber impregnation and a smooth surface;

[0033] The rod preform is cut into target lengths and placed in a preset mold cavity for heating and pressurizing for target durations, wherein the heating temperature ranges from 130° C. to 200° C. and the pressurizing pressure ranges from 2 MPa to 50 MPa;

[0034] The bone screw is obtained by cooling and demoulding.

[0035] In some embodiments, including but not limited to solid screws, hollow screws, full-thread screws, semi-thread screws, gate nails, intramedullary nails, pedicle screws, bone pins and other implants, the implants can be various thread structures, ring tooth structures, taper structures, inverted tooth structures, etc., as well as head-protecting brackets, connecting rods, adjustment rods and other rod-shaped implants. Based on the disclosure of the above embodiments, it can be known that the beneficial effects of the embodiments of the present invention include that the absorbable orthopedic implants use continuous fiber pre-impregnated resin composite wires / or strips, and are prepared in combination with polyester wires / or strips with excellent mechanical properties, good bone formation ability, and adjustable degradation rate. Implants can effectively avoid implant failure and late adverse reactions.

[0036] During the preparation process of the absorbable orthopedic implant preform, since there is only the last heating process, the heating process is less and the time is short, so the physical, chemical and mechanical properties of the material are better than those of the material in the existing preparation scheme including multiple processes, the influence of temperature on the matrix performance is reduced, and the polymer chain scission caused by long-term degradation of the prepared implant after entering the human body is avoided, the viscosity and molecular weight of the final product are improved, the degradation performance of the product during bone healing is enhanced, and the probability of nail breakage and nail removal during clinical use is reduced.

[0037] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0038] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 It is a schematic diagram of the cross-sectional structure of the absorbable bone screw in an embodiment of the present invention.

[0041] Figure 2 FIG. 4 is another schematic cross-sectional view of the absorbable bone screw in the embodiment of the present invention.

[0042] Figure 3 Schematic diagram of the cross-sectional morphology of the core body in an embodiment of the present invention.

[0043] Figure 4Schematic diagram of the cross-sectional morphology of the sleeve braided layer in an embodiment of the present invention.

[0044] Figure 5 This is a distribution diagram of the internal fiber orientation of the bone screw in the embodiment of the present invention under MicroCT.

[0045] Figure 6 Schematic diagram of the braiding angle between the bone screw thread and the external braided layer in an embodiment of the present invention,

[0046] Figure 7 The present invention is a flowchart of a method for preparing an absorbable bone screw according to an embodiment of the present invention.

[0047] Figure 8 It is a schematic diagram of the set-coding structure in an embodiment of the present invention.

[0048] Fig. 9 The figure is a process flow chart of the bone screw in the heating and pressurizing stages according to the embodiment of the present invention.

[0049] Fig.10 4 is a structural diagram of a grooved pressing roller in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but are not intended to limit the present invention.

[0051] It should be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the following description should not be considered as limiting, but merely as an example of an embodiment. Other modifications within the scope and spirit of the present disclosure will occur to those skilled in the art.

[0052] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the general description of the present disclosure given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

[0053] These and other characteristics of the invention will become apparent from the following description of a preferred form of embodiment given as a non-limiting example, with reference to the accompanying drawings.

[0054] It should also be understood that, although the invention has been described with reference to some specific examples, those skilled in the art will be able to realize many other equivalent forms of the invention that have the characteristics recited in the claims and are therefore within the scope of protection defined thereby.

[0055] The above and other aspects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0056] Specific embodiments of the present disclosure are described hereinafter with reference to the accompanying drawings; however, it should be understood that the disclosed embodiments are merely examples of the present disclosure, which may be implemented in a variety of ways. Well-known and / or repeated functions and structures are not described in detail to avoid obscuring the present disclosure with unnecessary or redundant details. Therefore, the specific structural and functional details disclosed herein are not intended to be limiting, but merely serve as a basis and representative basis for the claims to teach those skilled in the art to use the present disclosure in a variety of ways with substantially any suitable detailed structure.

[0057] This specification may use the phrases "in one embodiment," "in another embodiment," "in a further embodiment," or "in other embodiments," all of which may refer to one or more of the same or different embodiments according to the present disclosure.

[0058] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0059] like Figure 1 , Figure 2 and Figure 3 As shown, an embodiment of the present invention provides an absorbable bone screw, comprising:

[0060] The core 1 is a rod-shaped body made of composite material wire;

[0061] A first braided structure 2 is sleeved outside the core 1, wherein the first braided structure 2 is a mesh formed by weaving or winding continuous glass fiber pre-impregnated resin composite wire or tape;

[0062] A second set of braided structures 3 is set outside the first set of braided structures 2, and the second set of braided structures 3 is formed by calendering a polyester film sheet;

[0063] There is at least one first set of braided structures 2, and at least one second set of braided structures 3. At least the outermost first set of braided structures 2 is covered with the second set of braided structures 3.

[0064] For example, both the first set of braided structures 2 and the second set of braided structures 3 can be braided in multiple layers according to the needs. For example, the braiding order can be a layer of glass fiber layer and a layer of polyester layer, that is, a layer of the first set of braided structures 2 and a layer of the second set of braided structures 3, and the two sets of braided structures are arranged alternately, and the number of alternations is not limited. Or it can also be multiple layers of glass fiber layers and a layer of resin layer, that is, multiple layers of the first set of braided structures 2 are provided with a layer of the second set of braided structures 3, and the two sets of braided structures can also be arranged alternately based on this many-to-one form, and the number of alternations is not limited. The second set of braided structures 3 in this embodiment is set to avoid the wear of the glass fiber, that is, the first set of braided structures 2, to achieve the infiltration and wrapping of the glass fiber layer to form a smooth surface. Therefore, no matter how the first set of braided structures 2 and the second set of braided structures 3 are set, it must be ensured that the outermost layer of the bone screw must be a polyester silk braided layer, that is, the second set of braided structures 3.

[0065] In this embodiment, the total number of the sleeve braided structure can be 2-10 layers, preferably 2-5 layers, that is, a total of 2 to 5 layers of sleeve braided structure are set. For example, as an optional embodiment, the volume fraction of the glass fiber of the continuous glass fiber reinforced polyester absorbable bone nail is in the range of 5%-50%, and the volume fraction of the corresponding polyester matrix is ​​in the range of 50%-95%. Moreover, the mass fraction of the continuous fiber of the core 1 in the overall fiber after sleeve braiding is in the range of 0%-90%, and preferably the fiber mass fraction of the core 1 is 45%-65%.

[0066] Furthermore, the materials used for the sleeve-braided structure in this embodiment include glass fiber and polyester. Both raw materials are easy to obtain and easy to prepare, which provides convenience for the mass production of bone screws.

[0067] Based on the above content, it can be seen that the beneficial effects of this embodiment include that the absorbable bone screw is prepared by combining continuous glass fiber and polyester composite material, has excellent mechanical properties, good bone forming ability, and the degradation rate is controllable, which can effectively avoid implant failure and late adverse reactions. In addition, the screw thread area of ​​the absorbable bone screw obtained by molding is filled with fiber to ensure the structural strength of the screw thread and avoid screw thread damage and nail removal / retraction problems during use.

[0068] In practical applications, the product structure of the absorbable bone screw includes but is not limited to solid screws, hollow screws, full-thread screws, semi-thread screws, gate-shaped screws, intramedullary nails, pedicle screws, bone pins and other orthopedic implants, as well as connecting rods, adjustment rods and other rod-shaped implants. Specifically, in this embodiment, the absorbable bone screw has a diameter range of 0.3 mm-15 mm and a length range of 6 mm-420 mm. Of course, there is no specific limitation, and it can also be matched and adjusted according to actual needs.

[0069] When preparing the core 1, the core 1 includes a solid core 1 and a hollow core 1. The cross-sectional morphology thereof can be referred to Figure 3 The composite material wire is made by pultrusion of molten polyester impregnated continuous fibers, the diameter of the core 1 is any value within the range of 0.1 mm to 13 mm, and when the core 1 is made of the composite material wire, the fiber bundles in the composite material wire can be one bundle or multiple bundles.

[0070] Furthermore, the polyester substrate and continuous glass fiber in the bone nail preparation material are both biodegradable. Among them, the glass fiber in the continuous glass fiber pre-impregnated resin composite material wire and / or tape is absorbable bioactive glass fiber, and the linear density of the continuous glass fiber pre-impregnated resin composite material wire and / or tape is any value within the range of 20tex-2400tex, preferably any value within the range of 100tex-400tex. The continuous glass fiber pre-impregnated resin composite material wire and / or tape are then woven and / or wound to form a first set of braided structures, and the braiding density can be flexibly determined according to the glass fiber content requirements. The cross-sectional morphology of the first braided layer in this embodiment is referenced to Figure 4 shown.

[0071] The polyester film sheet is a homopolymer or a copolymer, and can also be a blend, including a random copolymer, a block copolymer or a graft copolymer. The bioabsorbable polyester can be a natural material or a synthetic material. For example, the bioabsorbable polyester includes but is not limited to PLA, PLLA, PDLLA, PGA, PLGA, PCL, PLLA-PCL and combinations thereof. That is, the polyester film sheet is formed by one or more polymers.

[0072] Similarly, the polyester film sheet is formed into a second braided structure by calendering, and the specific calendering layer can be determined according to the actual mechanical requirements. For the prepared bone nail, the internal fiber orientation distribution is observed by MicroCT. Figure 5 As shown, for the screw thread and the braiding angle of the outer sheath, please refer to Figure 6 shown.

[0073] Furthermore, in this embodiment, after the core body 1 is prepared, the first set of braided structures 2 and the second set of braided structures 3 are arranged in sequence. At this time, the structure in which the first set of braided structures 2 and the second set of braided structures 3 are arranged outside the core body 1 is a preform, and the preform is further processed through a process to form an absorbable bone nail, that is, the bone nail is formed by the preform formed by the core body 1, the first set of braided structures 2, and the second set of braided structures 3 in the initial state after being heated, cut, and molded.

[0074] In a specific application, the diameter and length of the bone screw need to be determined in advance, so as to restrict the preparation of the preform based on the diameter and length.

[0075] As an optional embodiment, the diameter of the bone nail formed by the core body 1, the first sleeve braiding structure 2, and the second sleeve braiding structure 3 is any value within the range of 0.3 mm to 15 mm, and the length is any value within the range of 6 mm to 420 mm.

[0076] like Figure 7 As shown, another embodiment of the present invention also provides a method for preparing an absorbable bone nail, comprising:

[0077] S1: obtaining materials for preparing a core body, a first set of braided structures, and a second set of braided structures, wherein the materials for preparing the core body include composite material wires, the materials for preparing the first set of braided structures include continuous glass fiber pre-impregnated resin composite material wires and / or tapes, and the materials for preparing the second set of braided structures include polyester film sheets;

[0078] S2: preparing a core body based on the composite wire material;

[0079] S3: forming a first braided structure based on the continuous glass fiber pre-impregnated resin composite wire material / or tape outside the core by weaving / winding;

[0080] S4: forming a second set of braided structures based on the polyester film sheet outside the first set of braided structures by calendering to form a preform;

[0081] S5: heating, shaping, cutting and molding the preform.

[0082] Get the bone nail.

[0083] Specifically, the step of obtaining materials for preparing the second set of braided structures includes:

[0084] S6: obtaining polyester pellets;

[0085] The polyester pellets are subjected to melt extrusion to obtain an initial polyester film sheet;

[0086] Further, in an optional embodiment, if Figure 8 As shown, a first braided structure is formed by weaving / or winding a continuous glass fiber pre-impregnated resin composite wire material / or tape outside the core body, including:

[0087] S7: adjusting the angle of the spindle based on the first pattern to be wound;

[0088] S8: installing a continuous glass fiber pre-impregnated resin composite material wire material or tape on the spindle, and controlling the spindle to run along a preset track, so that the continuous glass fiber pre-impregnated resin composite material wire material or tape can form one or more layers of the first braided structure on the surface of the core body in a one-press-one-weave / angle-winding manner;

[0089] The method of forming a second woven structure based on the polyester film sheet outside the first woven structure by calendering to form a preform comprises:

[0090] S9: obtaining polyester pellets;

[0091] S10: The polyester pellets are melt-extruded, and the molten polymer flow is guided to the casting head of the casting machine, extruded through the slit of the casting head and rapidly cooled to form a uniform film. The film and the first set of braided structures are placed in a mold, and pressure and heat are applied by a molding machine to shape the film material into a preform of a bone screw in the mold.

[0092] In this embodiment, the spindle running track and angle are adjustable. By adjusting the number of spindles or the running track, weaving and / or winding of different pattern shapes can be achieved. Moreover, while preparing different pattern shapes, the overall uniformity of the knitted structure can be ensured, that is, the structure of any area is uniform.

[0093] Optionally, when the sleeve braided structure is woven, the surface density of the sleeve braided structure can be adjusted, and it can be tightly woven or wound, or a certain amount of porosity can be retained. The surface density parameter can be adjusted according to the product performance requirements. For example, the porosity range is between 0% and 80%. In this embodiment, it is preferred that the first sleeve braided structure and the second sleeve braided structure are tightly woven, and the porosity range is within 0%-10%.

[0094] Furthermore, the preform is subjected to heating, shaping, cutting and molding to obtain a bone nail, comprising:

[0095] S11: heating the preform to a target temperature;

[0096] S12: The heated preform is subjected to pressurization and cooling treatment by two grooved rollers arranged opposite to each other, so as to obtain a rod preform with a regular cross section, sufficient fiber impregnation and a smooth surface;

[0097] S13: cutting the rod preform into a target length, and placing it into a preset mold cavity for a target length of time for heating and pressurizing;

[0098] S14: Cooling and demoulding to obtain the bone screw.

[0099] For example, Fig. 9 and Fig.10As shown, the preform is heated to a molten state by a heating area, and the molten preform is pressurized and cooled by a grooved roller located at the outlet of the heating area, thereby preparing a rod preform with a rounded cross section, good fiber impregnation, smooth surface and no exposed fibers. Among them, the heating area can be an integrated heater, or it can be formed by multiple heaters arranged in sections. In addition, for the heating temperature, only one temperature parameter can be set, or a temperature gradient can be set to heat based on the temperature gradient. The temperature parameter set in the heating area in this embodiment is within the temperature range of 170°C-300°C, and one or more temperature sections can be selected within the temperature range for the temperature gradient, for example, 1-5, preferably 2-3. The grooved rollers are two rollers arranged opposite to each other, each of which is provided with a groove, and the diameter of the groove ranges from 0.3mm to 15mm. The number of rollers can be 1-5 pairs, preferably 2-3 pairs. After the above process, the preform with good impregnation and smooth and round surface can be obtained by implementing an online one-time heating and pressurizing process in this embodiment, reducing the pre-impregnation in advance, the impregnation after weaving, or the heating process when weaving a multi-layer sleeve braided structure, which not only simplifies the process steps, but also reduces the influence of thermal history on material properties. After obtaining the rod preform, the rod preform can be processed by a traction device, cut to a fixed length using a tool, and then placed in a mold for heating and pressurizing treatment. After cooling and demolding, a bone nail product can be obtained. In this embodiment, when the heating treatment is performed in the mold, the heating temperature ranges from 130°C to 200°C, and the pressurizing pressure ranges from 2MPa to 50MPa.

[0100] The absorbable bone screw in this embodiment can obtain a preform with good impregnation and smooth and round surface after only one heating and pressurizing process in the preparation process, which reduces the process steps of pre-impregnation of the preparation material in advance, impregnation after weaving, or heating during the weaving of the multi-layer braided structure in the previous scheme, greatly simplifies the process steps, and reduces the influence of thermal history on material properties. That is, in the preparation process of the absorbable bone screw preform, since there is only one final heating process, the polyester wire material is subjected to fewer heating processes and the time is short, so that the physical and chemical and mechanical properties of the material are better than those of the material under the existing preparation scheme including multiple processes, and the influence of temperature on the matrix performance is reduced, and the polymer chain scission phenomenon caused by long-term degradation after the prepared bone screw is implanted in the human body can be effectively avoided, the viscosity and molecular weight of the final product are improved, the degradation performance of the product during bone healing is enhanced, and the probability of nail breakage and nail removal during clinical use is reduced.

[0101] In order to better describe the solution of the above embodiment, the following is explained in conjunction with specific application examples:

[0102] A single bundle of 1200tex continuous glass fiber is used as reinforcement, and polylactic acid pellets are used as the matrix and melt-extruded at 220°C. The continuous glass fiber is fully impregnated in the die head and pultruded through a die to obtain a core wire with a diameter of 2mm, also known as the core body.

[0103] Polylactic acid pellets are put into an extruder, and after melt extrusion, they are stretched by a pulling roller and then heated in an oven at a heating temperature of 80°C. They are then stretched by a second pulling roller, wherein the rotation speeds of the two pulling rollers are the same or different. In this embodiment, the rotation speed of the first pulling roller is 3m / min, and the rotation speed of the second pulling roller is 9m / min. After the above stretching, a polylactic acid filament with a stretching multiple of 3 and a diameter of 0.3mm is obtained and wound up.

[0104] A single bundle of 100tex continuous glass fiber pre-impregnated resin composite wire is used as the first outer braiding layer, that is, the first braiding structure. A total of 8 spindles are set up, which run according to the preset motion track. The surface of the core wire is braided into a net in a one-press-one manner to achieve tight weaving. The surface texture is as follows Figure 4 shown.

[0105] A polylactic acid film sheet with a thickness of 0.3 mm is used as the outer second sheathing layer, namely the second sheathing structure.

[0106] The rod preform was cut into 15mm lengths and placed in the mold cavity. The temperature was set to 170℃ and the pressure was 8MPa. The mold was closed, heated, and pressurized for 5 minutes. After cooling to room temperature, the mold was demolded to obtain an absorbable bone screw. The mechanical properties of the prepared continuous fiber sleeve reinforced bone screw and the polylactic acid self-reinforced bone screw were tested, and the data obtained were as follows:

[0107] Bone Screw Type Continuous fiber braided reinforced bone nail Polylactic acid self-reinforced bone screw Maximum shear load (N) 485.06 195.3 Maximum torque (Nm) 0.34 0.18

[0108] The above embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. An absorbable orthopedic implant, characterized in that: include: The core body is an inner layer structure formed by polyester / or unidirectional / multidirectional continuous fiber pre-impregnated resin composite wire material / or sheet material, and the composite wire material is made by a specific process; The first braided structure is sleeved on the outside of the core body and is formed by weaving or winding continuous fiber pre-impregnated resin composite wire or tape to form a mesh; The second braided structure is sleeved on the outside of the first braided structure and is made of polyester sheets and / or wires to form a preform by winding and / or weaving; The preform is subjected to heat shaping, cutting and molding treatment to obtain an orthopedic implant; wherein, the number of inner layer structures is 0-n, n is a positive integer, the number of the first set of braided structures is at least 1, and at least the outermost first set of braided structures is covered with the second set of braided structures.

2. The method for preparing the absorbable orthopedic implant according to claim 1, characterized in that: The core is prepared by a composite of continuous fiber and polyester material through a melt impregnation pultrusion process / or its melt impregnation pultrusion layer layer stacking and other molding processes. The composite material ratio can be designed according to mechanical requirements. The core fiber mass fraction is between 0-95%, and the core diameter or / length and width should be ≥0.1mm.

3. The method for preparing the absorbable orthopedic implant according to claim 1, characterized in that: The first braided structure is woven by continuous fiber pre-impregnated resin composite wire material, or wound by continuous fiber pre-impregnated resin composite tape material, and the fiber mass fraction of the wire material / tape material is between 0-95%.

4. The method for preparing the absorbable orthopedic implant according to claim 1, characterized in that: The second braided structure is made of polyester sheets and / or wires and is formed into a preform by winding and / or braiding.

5. The absorbable orthopedic implant according to claim 1, characterized in that: The core includes but is not limited to a solid core and / or a hollow core.

6. The absorbable orthopedic implant according to claim 1, characterized in that: The reinforcing fibers in the continuous fiber pre-impregnated resin composite material wire and / or tape include but are not limited to degradable fibers such as glass fiber and basalt fiber, and the fiber content is between 0% and 90%; the linear density of the continuous fiber is any value or combination within 20tex-2400tex, and the continuous fiber pre-impregnated resin composite material wire and / or tape is a first set of braided structures, which can be braided or wound on the outside of the core body through weaving and / or winding to achieve tight weaving or winding, and the porosity range is between 0-80%.

7. The absorbable orthopedic implant according to claim 1, characterized in that: The second braided structure is composed of polyester sheets and / or filaments, which can be homopolymers, copolymers or blends, formed by one or more polymers, wherein the bioabsorbable polyester can be a natural material or a synthetic material, including but not limited to, the bioabsorbable polyester includes but is not limited to polylactide (PLA), poly-L-lactide (PLLA), poly-DL-lactide (PDLLA) polyglycolide (PGA), polylactide glycolic acid (PLGA), polycaprolactone (PCL), poly(L-lactide-co-caprolactone) (PLLA-PCL) and combinations thereof, and the polyester sheets and / or filaments are the second braided structure, which is arranged outside the first braided structure by winding and / or weaving.

8. The absorbable orthopedic implant according to claim 1, characterized in that: The diameter of the absorbable orthopedic implant formed by the core, the first set of braided structures, and the second set of braided structures is not less than 0.3 mm, and can be customized to a larger size as needed (for practical application and optimization considerations, the recommended diameter range is maintained at 0.3 mm-20 mm); the length is not less than 6 mm, and can be extended to a longer size as needed.

9. The absorbable orthopedic implant according to claim 8, characterized in that: The absorbable orthopedic implant is formed by a preform formed by an initial core, a first set of braided structures, and a second set of braided structures, which is subjected to heat shaping, cutting, and molding. The diameter of the preform is positively correlated with the diameter of the implant, and the inner core structure can be 0.

10. A method for preparing an absorbable orthopedic implant, characterized in that: include: Obtaining materials for preparing a core body, a first set of braided structures, and a second set of braided structures, wherein the materials for preparing the core body include composite wires, the materials for preparing the first set of braided structures include continuous fiber pre-impregnated resin composite wires / or tapes, and the materials for preparing the second set of braided structures include polyester sheets / or wires; Preparing a core inner layer structure based on the polyester / or unidirectional / multidirectional continuous fiber pre-impregnated resin composite wire material / or sheet material; Based on the continuous fiber pre-impregnated resin composite wire material / or tape, a first set of braided structures is formed by weaving / or winding outside the core; based on the polyester / or composite sheet / or wire material, a second set of braided structures is formed by winding / or weaving outside the first set of braided structures to form a preform; The preform is heated, shaped, cut and molded to obtain an absorbable orthopedic implant.

11. The method for preparing the absorbable orthopedic implant according to claim 10, characterized in that: Based on the continuous fiber pre-impregnated resin composite wire material / or tape outside the core, a first braided structure is formed by weaving / or winding, including: The continuous fiber pre-impregnated resin composite material wire material or tape is installed on a weaving spindle or a winding turntable, and the spindle or the turntable is controlled to run according to a preset track, so that the continuous fiber pre-impregnated resin composite material wire material or tape can be pressed and woven or wound at an angle on the surface of the core body to form one or more layers of the first braided structure; Based on the polyester sheet material / wire material, a second braided structure is formed by winding / or weaving outside the first braided structure to form a preform, including: obtaining polyester pellets, and melt-extruding / calendering / or forming the polyester pellets to form a uniform sheet material / wire material. The sheet material / wire material and the first braided structure are mounted on the braiding spindle / or winding turntable, and the spindle / or turntable is controlled to run according to a preset track, so that the resin sheet material / wire material can be formed outside the first braided structure in a one-pressing and one-weaving / or angled winding manner to form a preform of the implant.

12. The method for preparing the absorbable orthopedic implant according to claim 10, characterized in that: The preform is subjected to heating, shaping, cutting and molding to obtain an absorbable orthopedic implant, comprising: The preform is heated to a target temperature, wherein the temperature parameters of the heating zone are set within a temperature range of 170° C. to 300° C.; The heated preform is pressed and cooled by two grooved rollers arranged opposite to each other to obtain a profile preform with a regular cross section, sufficient fiber impregnation and a smooth surface; The rod preform is cut into target lengths and placed in a preset mold cavity for heating and pressurizing for target durations, wherein the heating temperature ranges from 130° C. to 200° C. and the pressurizing pressure ranges from 2 MPa to 50 MPa; The bone screw is obtained by cooling and demoulding.

13. The preparation method described in the claim is described in the specification as being generally applicable to orthopedic implants, including but not limited to solid screws, hollow screws, fully threaded screws, semi-threaded screws, gate-type nails, intramedullary nails, pedicle screws, bone needles and other implants. The implants may be various thread structures, annular tooth structures, tapered structures, inverted tooth structures, etc., as well as rod-shaped implants such as head-protecting brackets, connecting rods, and adjusting rods.

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