Intramedullary nail and manufacturing method thereof

Abstract

The invention provides an intramedullary nail and a manufacturing method of the intramedullary nail, the intramedullary nail is made of silk protein, the intramedullary nail comprises a skeleton and a plurality of fiber layers formed on the skeleton, and each fiber layer is pressurized and fixed through silk protein liquid. According to the intramedullary nail and the manufacturing method of the intramedullary nail, the silk protein is adopted as a raw material to manufacture the intramedullary nail, so that the intramedullary nail can be automatically degraded in a human body, the nail taking process is omitted, and harm to the human body is reduced; according to the intramedullary nail, the skeleton is formed firstly, and then the multiple fiber layers are formed, so that the intramedullary nail is higher in mechanical strength, higher in supporting effect, higher in fatigue resistance and controllable in degradation rate.

Description

Technical Field

[0001] The invention relates to an intramedullary nail and a method for manufacturing the intramedullary nail. Background Art

[0002] As an internal fixation device for long bone fractures, traditional metal materials (stainless steel, titanium alloy) are difficult to meet the long-term clinical application needs due to poor biocompatibility, the need for secondary surgery to remove, and stress shielding. The rigidity modulus of metal materials is much higher than that of human bones, resulting in an imbalance in the stress distribution in the bone regeneration area, which may cause inflammatory reactions and osteoporosis.

[0003] Silk protein-based materials have become an ideal alternative due to their excellent biocompatibility, degradability and flexibility. Studies have shown that silk protein materials can promote bone cell growth and improve the microenvironment of fracture healing, and their flexibility can reduce the stress shielding effect.

[0004] However, the existing silk protein intramedullary nails have insufficient mechanical properties, and their bending strength is only equivalent to 15% to 30% of the human tibia, which cannot meet the load-bearing requirements of heavy patients. In addition, the degradation rate of silk protein is uncontrollable and can only gradually degrade after a period of time after the fracture has recovered. It cannot begin to degrade as the fracture recovers, nor can it gradually and naturally stress the fracture area and accelerate fracture recovery.

[0005] In view of this, it is necessary to improve the existing method for making intramedullary nails to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to provide an intramedullary nail and a method for making the intramedullary nail, so as to solve the problems of insufficient strength and uncontrollable degradation rate of existing silk protein.

[0007] To achieve the above object, the present invention provides an intramedullary nail, which is made of silk protein and includes a skeleton and multiple fiber layers formed on the skeleton, and each fiber layer is fixed by pressurizing with silk protein liquid.

[0008] As a further improvement of the present invention, different drugs are added into each fiber layer of the intramedullary nail.

[0009] As a further improvement of the present invention, the skeleton includes a main body and a plurality of branches.

[0010] The present invention also provides a method for manufacturing an intramedullary nail, the method comprising the following steps: S1: Collect human data and design intramedullary nails; S2: Design a skeleton mold and use silk protein liquid to pour into the skeleton mold to form a skeleton; S3: Spinning silk protein on the skeleton surface to form a fiber layer; S4: designing an intramedullary nail mold, placing the skeleton with the fiber layer in step S3 into the intramedullary nail mold, and using silk protein liquid to pour into the intramedullary nail mold to complete pressurized fixation of the fiber layer; S5: repeating steps S3 and S4 to spin to form multiple fiber layers, and pressurizing and fixing the multiple fiber layers respectively until the intramedullary nail is manufactured.

[0011] As a further improvement of the present invention, the spinning method in step S3 is an electrostatic spinning method.

[0012] As a further improvement of the present invention, in step S3, the fiber layer is divided into at least a fast degradation layer close to the skeleton and a slow degradation layer far away from the skeleton, the fiber diameter of the fast degradation layer is smaller than the fiber diameter of the slow degradation layer, and the spinning voltage of the fast degradation layer is lower than the spinning voltage of the slow degradation layer.

[0013] As a further improvement of the present invention, in step S3, the spinning voltage of the fast degradation layer is in the range of 5-10 kV, and the spinning voltage of the slow degradation layer is in the range of 15-30 kV.

[0014] As a further improvement of the present invention, in step S5, the spinning voltage of the woven fiber layer in the repeated step S3 is gradually increased from the inside to the outside.

[0015] As a further improvement of the present invention, the fiber layer formed in step S3 is added with drugs, and the fiber layer formed in step S3 repeated in step S5 is added with different drugs.

[0016] As a further improvement of the present invention, in step S4, drugs are added to the silk protein solution, and in step S5, different drugs are added to the silk protein solution in step S4 which is repeated.

[0017] As a further improvement of the present invention, the method for manufacturing the intramedullary nail further includes step S6 after step S5: grinding, polishing, cleaning and inspecting the manufactured intramedullary nail.

[0018] As a further improvement of the present invention, the method for making the intramedullary nail further includes step S7: making a nail hole.

[0019] The beneficial effects of the present invention are as follows: the intramedullary nail and the method for making the intramedullary nail of the present invention use silk protein as a raw material to make the intramedullary nail, so that the intramedullary nail can be self-degraded in the human body, eliminating the nail removal process and reducing damage to the human body; by first forming a skeleton and then forming multiple fiber layers, the intramedullary nail has higher mechanical strength, stronger supporting effect, higher fatigue resistance, and a controllable degradation rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 It is a schematic diagram of the structure of the intramedullary nail of the present invention; Figure 2 It is a schematic structural diagram of the skeleton of the intramedullary nail of the present invention; Figure 3 is a schematic diagram of the intramedullary nail of the present invention forming a fiber layer on the skeleton; Figure 4 is a method schematic diagram of step S3 of the method for manufacturing an intramedullary nail of the present invention; Figure 5 is a method schematic diagram of step S4 of the method for manufacturing an intramedullary nail of the present invention; Figure 6 It is a flow chart of the method for manufacturing the intramedullary nail of the present invention. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0022] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] like Figure 1 As shown, the intramedullary nail of the present invention is made of silk protein, and the intramedullary nail includes a skeleton and multiple fiber layers formed on the skeleton, and each fiber layer is pressurized and fixed by silk protein liquid.

[0025] Silk protein has good compatibility with the human body, so that the intramedullary nail can degrade itself in the human body, eliminating the nail removal process and reducing harm to the human body.

[0026] The skeleton includes a main body and multiple branches, and the lengths of the multiple branches are different, corresponding to the thickness of different areas of the intramedullary nail. The branches are longer in thick areas and shorter in thin areas. The design and manufacturing process of the intramedullary nail of this embodiment refer to both heart tissue and tree trunks, and the principle of the manufactured product is similar to human tissue (bone attached to muscle). The skeleton of this embodiment integrates the principle of bionics. In the design, it fully draws on the flexibility and adaptability of heart tissue, as well as the firmness and growth characteristics of tree trunks, giving the intramedullary nail excellent biocompatibility, mechanical properties and functional adaptability.

[0027] Different drugs are added to each fiber layer of the intramedullary nail. The drugs here can be osteoinductive units to enhance bone growth, or they can be anti-inflammatory substances to avoid inflammation during fracture repair. And adding different substances to different layers can deal with different situations. The drugs will be released after the designated silk fiber layer is dissolved, that is, the drug can be released in a controlled manner.

[0028] The intramedullary nail of the present invention has a stronger supporting effect and higher fatigue resistance.

[0029] The intramedullary nail is manufactured by adopting a manufacturing method of an intramedullary nail.

[0030] The method for making an intramedullary nail comprises the following steps: S1: Collect human data and design intramedullary nails; S2: Design a skeleton mold and use silk protein liquid to pour into the skeleton mold to form a skeleton; S3: Spinning silk protein on the skeleton surface to form a fiber layer; S4: designing an intramedullary nail mold, placing the skeleton with the fiber layer in step S3 into the intramedullary nail mold, and using silk protein liquid to pour into the intramedullary nail mold to complete pressurized fixation of the fiber layer; S5: repeating steps S3 and S4 to spin to form multiple fiber layers, and pressurizing and fixing the multiple fiber layers respectively until the intramedullary nail is manufactured; S6: grinding, polishing, cleaning and inspecting the manufactured intramedullary nail; S7: Make nail holes.

[0031] In step S1, the intramedullary nail is made using real human body data. Its inclination angle is adjusted by referring to the real data, generally between 5-10°. It is divided into a primary locking nail hole and a secondary locking nail hole. The primary locking nail hole is generally set at the head and has an inclination angle, which plays an anti-rotation role after the locking screw is placed here. The secondary locking nail hole is generally set at the bottom, and the angle is set according to the situation, generally perpendicular to the axis of the intramedullary nail.

[0032] The spinning method in step S3 is electrospinning. The manufacturing principle is to control the direction and diameter of the fiber by adjusting the voltage of the electrospinning machine during electrospinning.

[0033] In step S3, the fiber layer is divided into at least a fast degradation layer close to the skeleton and a slow degradation layer far from the skeleton, the fiber diameter of the fast degradation layer is smaller than the fiber diameter of the slow degradation layer, wherein the spinning voltage of the fast degradation layer is lower than the spinning voltage of the slow degradation layer. The slow degradation layer has a larger fiber diameter, so it can achieve slow degradation, and has a good supporting effect before the fracture position is completely healed.

[0034] In step S3, the spinning voltage of the fast-degrading layer is in the range of 5-10 kV, and the spinning voltage of the slow-degrading layer is in the range of 15-30 kV.

[0035] Moreover, in step S5, the spinning voltage of the woven fiber layer in the repeated step S3 gradually increases from the inside to the outside. It should be emphasized that the spinning voltages of the fast degradation layer and the slow degradation layer are gradually increased from the inside to the outside. First, the internal fast degradation layer is made, and the voltage range of the electrospinning machine is relatively low during the production. For example, first use 5kV to make a layer of fiber on the surface of the skeleton, and then use 5.5kV to make the second layer of fiber, and so on. The voltage gradient is determined by how many layers of fiber you want to make. The fiber diameter of the fast degradation layer is smaller, so it can be degraded quickly. The fiber diameter of the slow degradation layer is larger and more compact, and the voltage range is 15-30kV.

[0036] As the fracture recovers and gradually degrades, its supporting strength gradually decreases with the recovery process. The fracture area can continuously and gradually increase the load-bearing force, helping the function of the fracture site to recover more naturally. Specifically, the silk protein fibers on the outside have a larger diameter and density, and it can be determined that they will gradually begin to degrade after the initial recovery of the fracture. Then, after the coarse fibers on the outside are degraded, the fracture has basically recovered at this time, and the fine fibers inside degrade faster and can be degraded in a very short period of time. The skeleton will continue to maintain the supporting strength of the entire nail during the degradation process to avoid uneven stress distribution due to fiber degradation.

[0037] In order to produce multiple layers of silk protein fibers with inconsistent arrangement directions, step S3 increases the support strength and controllable degradation rate. Such an arrangement imitates the arrangement of myocardial fibers in the heart. Because the heart is composed of multiple layers of myocardial fibers with different arrangements, the myocardial fibers arranged in different directions are intertwined with each other, just like building an intricate network structure. This structure gives the heart good stability, making it less likely to deform in shape. Therefore, by setting step S3, the obtained intramedullary nail has better stability. In addition, the present invention can adjust the direction of the fiber to enhance the stress of the intramedullary nail in different areas. During production, it is only necessary to adjust the voltage of the electrospinning machine to change the direction of the fiber (the voltage can be continuously changed), and the adjustment is more convenient.

[0038] The fiber layer formed in step S3 is added with drugs, and the fiber layer formed in step S3 repeated in step S5 is added with different drugs. Since multiple fiber layers are provided and each fiber layer is independently spun, the effect of adding different drugs to different fiber layers can be achieved.

[0039] The purpose of step S4 is to perform pressurized fixation, which is to pressurize and fix the produced silk protein fibers on the skeleton. The specific process is to place the skeleton after electrospinning inside the intramedullary nail mold, and then pour the silk protein solution from the silk protein main pouring port of the upper mold. The silk protein solution will be poured into the corresponding intramedullary nail area from the silk protein sub-pouring port, and pressurize from the main pouring port to enhance the contact between the solutions.

[0040] In addition to adding drugs in step S3, different drugs are added to the silk protein solution in step S4 repeated in step S5. Drugs can be added in two steps or in one step. In step S3, drugs can be added. Here, the drugs can be dissolved in the silk protein solution and then spun, or the drugs can be sprinkled on the limiting layer after the fiber layer is made, and then the silk protein solution is poured to cover the drugs; in step S4, drugs are added, and the drugs are directly mixed with the silk protein solution and then poured.

[0041] In addition, in this embodiment, multiple fiber layers are provided, which allows the intramedullary nail to carry a variety of drugs, ensuring that different drugs are released at different times, thereby increasing the versatility of the intramedullary nail.

[0042] Step S5, taking the nail out of the mold after solidification is complete, and repeating the electrospinning and pressurizing and fixing operations until the preliminary production of the intramedullary nail is completed.

[0043] After the intramedullary nail is initially manufactured, that is, when the intramedullary nail has reached the expected diameter, it is necessary to perform grinding in step S6 to eliminate the minor flaws, protrusions and unevenness on the surface of the intramedullary nail one by one. The grinding process requires the use of high-precision grinding equipment and fine sandpaper, following the grinding sequence from coarse to fine. First, use coarse sandpaper to initially grind off the more obvious rough parts, and then switch to fine sandpaper for fine grinding to make the surface of the intramedullary nail smoother. During the grinding period, the grinding force and speed must be strictly controlled to avoid deviations in the diameter of the intramedullary nail due to excessive grinding, which affects its fit with the medullary cavity.

[0044] After grinding, the intramedullary nail is cleaned in all aspects. An ultrasonic cleaner is used to completely remove metal debris, abrasive particles and other impurities remaining on the surface of the nail body during the grinding process to ensure that the surface of the intramedullary nail is clean and free of dirt.

[0045] Subsequently, the intramedullary nail is surface polished by electrochemical polishing or mechanical polishing to further improve the surface smoothness of the intramedullary nail and reduce its surface roughness. This not only helps to reduce the friction damage to the surrounding tissues after the intramedullary nail is implanted in the human body, but also enhances its corrosion resistance and prolongs its service life.

[0046] After polishing, the intramedullary nail must undergo strict quality inspection. High-precision measuring instruments are used to detect whether key dimensions such as diameter and length meet the standards. An electron microscope is used to observe the surface microstructure to check for defects such as microcracks generated during the grinding or polishing process.

[0047] There are two ways to make the nail holes in step S7. One is to use a specific rod to fix it on the frame before making it, and then perform subsequent operations. After making it, the rod is removed, and the reserved space is the designated nail hole. If this method is adopted, step S7 is not limited to be performed after step S6.

[0048] Another way is to use a punching tool to drill holes after the production is completed. It should be noted that the holes are drilled in sequence using drill bits with increasing diameters. First, a small diameter drill bit is used to drill the positioning hole, and then a drill bit with increasing diameter is used to expand the diameter of the nail hole. This can avoid problems such as nail hole cracking. If this method is used, step S7 needs to be performed after step S6.

[0049] The intramedullary nail and the method for making the intramedullary nail of the present invention adopt silk protein as the raw material to make the intramedullary nail, so that the intramedullary nail can be self-degraded in the human body, eliminating the nail removal process and reducing harm to the human body; by first forming a skeleton and then forming multiple fiber layers, the intramedullary nail has higher mechanical strength, stronger supporting effect, higher fatigue resistance and controllable degradation rate.

[0050] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An intramedullary nail, characterized in that: The intramedullary nail is made of silk protein and comprises a skeleton and multiple fiber layers formed on the skeleton, and each fiber layer is fixed by pressurizing with silk protein liquid.

2. The intramedullary nail according to claim 1, characterized in that: Different drugs are added into each fiber layer of the intramedullary nail.

3. The intramedullary nail according to claim 1, characterized in that: The skeleton includes a main body and a plurality of branches.

4. A method for manufacturing an intramedullary nail, characterized in that: The method for making the intramedullary nail comprises the following steps: S1: Collect human data and design intramedullary nails; S2: Design a skeleton mold and use silk protein liquid to pour into the skeleton mold to form a skeleton; S3: Spinning silk protein on the skeleton surface to form a fiber layer; S4: designing an intramedullary nail mold, placing the skeleton with the fiber layer in step S3 into the intramedullary nail mold, and using silk protein liquid to pour into the intramedullary nail mold to complete pressurized fixation of the fiber layer; S5: repeating steps S3 and S4 to spin to form multiple fiber layers, and pressurizing and fixing the multiple fiber layers respectively until the intramedullary nail is manufactured.

5. The method for manufacturing an intramedullary nail according to claim 4, characterized in that: The spinning method in step S3 is electrostatic spinning.

6. The method for manufacturing an intramedullary nail according to claim 5, characterized in that: In step S3, the fiber layer is divided into at least a fast degradation layer close to the skeleton and a slow degradation layer far from the skeleton, the fiber diameter of the fast degradation layer is smaller than the fiber diameter of the slow degradation layer, and the spinning voltage of the fast degradation layer is lower than the spinning voltage of the slow degradation layer.

7. The method for manufacturing an intramedullary nail according to claim 6, characterized in that: In step S3, the spinning voltage of the fast-degrading layer is in the range of 5-10 kV, and the spinning voltage of the slow-degrading layer is in the range of 15-30 kV.

8. The method for manufacturing an intramedullary nail according to claim 5, characterized in that: In step S5, the spinning voltage of the woven fiber layer in the repeated step S3 is gradually increased from the inside to the outside.

9. The method for manufacturing an intramedullary nail according to claim 4, characterized in that: The fiber layer formed in step S3 is added with a drug, and the fiber layer formed in step S3 repeated in step S5 is added with a different drug.

10. The method for manufacturing an intramedullary nail according to claim 4, characterized in that: In step S4, drugs are added to the silk protein solution, and in step S5, different drugs are added to the silk protein solution in step S4 which is repeated.

11. The method for manufacturing an intramedullary nail according to claim 4, characterized in that: The method for manufacturing the intramedullary nail further comprises step S6 after step S5: grinding, polishing, cleaning and inspecting the manufactured intramedullary nail.

12. The method for manufacturing an intramedullary nail according to claim 11, characterized in that: The method for manufacturing the intramedullary nail further comprises step S7: making a nail hole.

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