In-vivo degradable anastomosis nail and preparation method thereof

Abstract

The invention relates to an anastomosis nail capable of being degraded in vivo and a preparation method thereof, the anastomosis nail is of a U-shaped structure and comprises a cross beam and two nail legs located at the two ends of the cross beam; the anastomosis nail is made of magnesium alloy, and the magnesium alloy is prepared from, by weight, 1%-2% of Al, 1%-1.5% of Zn, 0.5%-1.2% of Mn, 0.1%-0.6% of Ca and the balance Mg. The anastomosis nail is formed by processing a magnesium alloy wire, and the diameter of the magnesium alloy wire for manufacturing the anastomosis nail is 0.2 mm-0. 6mm. The anastomosis nail can meet the mechanical property requirement of soft tissue in an anastomosis body and the requirement of wound healing, and has a good technical effect.

Description

Technical Field

[0001] This invention relates to the field of medical devices, and in particular to a biodegradable anastomotic staple and its preparation method. Background Technology

[0002] Anastomosis staples are widely used surgical instruments for suturing incisions. They are convenient, quick, and simple to operate, significantly shortening operation time, reducing trauma and bleeding, effectively reducing surgical complications, and improving the safety of surgical procedures. Currently, the materials used for anastomosis staples in surgery are mainly inert metals such as titanium and titanium alloys. These are non-biodegradable in the body and remain permanently as foreign bodies, potentially impacting the patient's future life.

[0003] Magnesium is one of the most important elements in the human body, participating in numerous enzymatic reactions and acting as an activator for over 300 enzymes. The average magnesium content in a normal adult body is reported to be approximately 21-28 grams, with over 50% found in bone tissue, 35-40% in soft tissue, and about 1% in serum. Magnesium is the fourth most abundant cation in the human body, and within cells, Mg²⁺ is considered the second most abundant. Mg²⁺ ions play a crucial role in cellular function, regulating muscle excitability and improving cardiac metabolism. Research by the Chinese Nutrition Society indicates that adult men and women require approximately 350 mg and 300 mg of magnesium daily, respectively, with a tolerable daily intake of up to 700 mg. Therefore, magnesium alloys offer high biocompatibility as biomedical materials. Because magnesium is chemically reactive, magnesium alloy implants will automatically degrade during long-term implantation in the human body, releasing non-toxic metal ions and creating a local alkaline environment. This effectively inhibits bacterial adsorption, promotes wound healing, and avoids the inflammatory reactions caused by the release of toxic ions from commonly used titanium alloy and other medical metal implants. Although biomedical magnesium alloys show great promise, their practical clinical application is currently limited. This is mainly because biodegradable medical implants (such as bone screws, cardiac stents, and anastomotic staples) have strict requirements for the comprehensive mechanical properties of the materials. They not only need sufficient strength to serve as structural components but also good deformation capacity to be processed into thin rods, wires, and nail-shaped medical devices. Currently, many institutions at home and abroad are researching the preparation methods of medical magnesium alloy anastomotic staples. Patent application publication number CN111434791A improves the strength of the local bending points of the anastomotic staple through annealing treatment, preventing breakage during preparation. However, this only satisfies the mechanical properties of the anastomotic staple but does not investigate whether the degradation rate of the anastomotic staple meets the requirements for wound healing. Foreign patent US2017 / 0056007A1 discloses a method of covering part (but not all) of the surface of a nail with a bioabsorbable polymer. The portion of the nail not covered by the bioabsorbable polymer is absorbed at a faster rate, while the portion covered is absorbed at a slower rate. This method is difficult to manufacture and not easily implemented. Therefore, there is an urgent need to develop a medical magnesium alloy that is easy to manufacture and whose strength and degradation rate of the anastomotic staple meet clinical requirements. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0005] A biodegradable anastomotic staple, the staple having a U-shaped structure including a crossbeam and two staple legs located at both ends of the crossbeam; the staple is made of magnesium alloy, the composition of which, by weight percentage, is: 1-2% Al, 1-1.5% Zn, 0.5-1.2% Mn, 0.1-0.6% Ca, with the balance being Mg; the staple is made of magnesium alloy wire, the diameter of which is also the diameter of the staple, is 0.2mm-0.6mm.

[0006] Furthermore, the diameter is 0.23 mm.

[0007] Furthermore, the angle between the nail leg and the crossbeam is 90°-100°, the length of the crossbeam is 2.6mm-10mm, and the height of the nail leg is 2.0mm~5.5mm.

[0008] Furthermore, the top of the spike leg is designed with a sloping structure, with an included angle of 30°~40°.

[0009] The preparation method of the anastomotic staple is as follows: various metals are mixed and melted into liquid metal, the slag is removed, and the metal is cast into magnesium alloy ingots. After heat treatment, the magnesium alloy ingots are extruded and drawn in multiple passes to make wire. After annealing, the wire is made into anastomotic staples.

[0010] Furthermore, under the protection of argon gas, an alloy consisting of 1-2% Al, 1-1.5% Zn, 0.5-1.2% Mn, 0.1-0.6% Ca, and the balance Mg by weight is melted into a liquid metal at a high temperature of 650℃-1250℃. After static filtration to remove slag, the molten metal is cast into magnesium alloy ingots. After heat treatment at 400℃ for 8 hours, multiple extrusion drawing is performed at a drawing temperature of 350℃, with a single-pass drawing deformation of 20%-30% and a drawing speed of 20 mm / s. Finally, wires with a diameter of 0.2-0.6 mm are produced and annealed at 200℃ for 60 minutes. The obtained magnesium alloy wires are then processed into matching staples using a staple-making machine.

[0011] Furthermore, it is melted into liquid metal at high temperatures of 660℃-850℃.

[0012] The technical solution of this application has the following beneficial effects:

[0013] 1. The staples of this application have good mechanical strength and deformation capacity.

[0014] 2. The staples of this application have good suture strength and pressure resistance.

[0015] 3. The anastomotic staples of this application have good degradation ability.

[0016] 4. The anastomosis staple processing method of this application is simple and easy to implement. Attached Figure Description

[0017] The above is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] Figure 1 This is a schematic diagram of the anastomosis staple structure of the present invention;

[0019] Figure 2 These are actual images of the anastomotic staples of the present invention before and after anastomosis.

[0020] Figure reference numerals: 101 Screw, 102 Crossbeam, 103 Sloping structure at the top of the screw, R1 Angle between the crossbeam and the screw, R2 Inclination angle of 103. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] A biodegradable anastomotic staple, the staple having a U-shaped structure including a crossbeam and two staple legs located at both ends of the crossbeam; the staple is made of magnesium alloy, the composition of which, by weight percentage, is: 1-2% Al, 1-1.5% Zn, 0.5-1.2% Mn, 0.1-0.6% Ca, with the balance being Mg; the staple is processed from magnesium alloy wire, and the diameter of the magnesium alloy wire used to make the staple, which is also the diameter of the staple, is 0.2mm-0.6mm. Preferably, the diameter is 0.23mm.

[0024] The angle between the nail leg and the crossbeam is 90°-100°, the length of the crossbeam is 2.6mm-10mm, and the height of the nail leg is 2.0mm-5.5mm. The top of the nail leg has a sloping structure with an angle of 30°-40°, which is conducive to penetrating tissue.

[0025] Magnesium is an essential trace element for human metabolism, with an average magnesium content of about 21-28 grams in a normal adult body. Magnesium alloys have excellent biocompatibility, can degrade in the human body, and the degradation product Mg2+ is non-toxic and will not cause inflammation or allergic reactions. Excess magnesium ions can also be metabolized and excreted through the kidneys without cumulative effects. Magnesium alloys are ideal medical implant materials.

[0026] Regarding the selection of trace elements, the addition of aluminum (Al) can improve the high-temperature mechanical properties of magnesium alloys. However, Al is a non-essential trace element for the human body and its metabolic capacity is relatively weak. Therefore, to ensure high-temperature mechanical properties while minimizing its impact on human health, the recommended Al content in magnesium alloy products is 1%-2%. Excessive Al may have adverse effects on the human body, while insufficient Al has minimal impact on high-temperature mechanical properties. Manganese (Mn) is one of the essential trace elements for the human body. The adult human body contains approximately 10-30 mg of manganese. Manganese and manganese ions play an important role in human health, acting as activators of various enzymes and participating in the activation of over 100 enzymes. It is closely related to the synthesis of sugars, amino acids, proteins, cholesterol, and fat metabolism. Adding manganese to magnesium alloys can significantly improve the alloy's corrosion resistance, refine grain size, improve room-temperature mechanical properties, and enhance formability during extrusion, while also being beneficial to human health. Zinc (Zn) is an essential trace element for the human body, playing a vital role in maintaining life activities. Zn regulates the body's immune function, maintains normal male physiological functions, promotes normal development in children, and promotes ulcer healing. Adding a certain amount of zinc to magnesium alloys helps mitigate the adverse effects of impurities such as Fe and Ni on the corrosion resistance of magnesium alloys and can form a protective film on the surface of the magnesium alloy. Calcium (Ca) is an essential element for the human body; appropriate addition can improve the biosafety of medical magnesium alloys and enhance the antioxidant capacity of the melt surface. In summary, the aluminum alloy of this application, in addition to Mg, incorporates Al, Zn, Mn, and Ca elements. Experiments have shown that while ensuring benefits to the human body, the magnesium alloy also possesses good performance. The composition of the magnesium alloy is selected as follows: 1-2% Al, 1-1.5% Zn, 0.5-1.2% Mn, 0.1-0.6% Ca, with the balance being Mg.

[0027] The preparation method of the anastomotic staple is as follows: various metals are mixed and melted into liquid metal, the slag is removed, and the metal is cast into magnesium alloy ingots. After heat treatment, the magnesium alloy ingots are extruded and drawn in multiple passes to make wire. After annealing, the wire is made into anastomotic staples.

[0028] Specifically, under the protection of argon gas, an alloy containing 1-2% Al, 1-1.5% Zn, 0.5-1.2% Mn, 0.1-0.6% Ca, and the balance Mg by weight is melted into a liquid metal at a high temperature of 660℃-1250℃. After standing and filtering to remove slag, the molten metal is cast into magnesium alloy ingots. After heat treatment at 400℃ for 8 hours, it undergoes multiple extrusion drawing at a temperature of 350℃, with a single-pass deformation of 20%-30% and a drawing speed of 20 mm / s. Finally, wires with a diameter of 0.2-0.6 mm are produced and annealed at 200℃ for 60 minutes. The obtained magnesium alloy wires are then processed into various specifications of matching nails using a nail-making machine.

[0029] Example

[0030] Magnesium alloy wires were prepared using the method described above, with the following weight percentages: Mg + 1.6%Al + 1.5%Zn + 0.8%Mn + 0.2%Ca, Mg + 1.8%Al + 1.5%Zn + 0.8%Mn + 0.2%Ca, and Mg + 1.6%Al + 1.5%Zn + 0.5%Mn + 0.25%Ca, respectively.

[0031] The mechanical properties of magnesium alloy wire were tested: tensile strength, yield strength, and elongation. The obtained magnesium alloy wire was processed into anastomotic staples of various specifications using a stapler, and then inserted into corresponding models of anastomotic devices. The staple formation, suture strength, and anastomotic pressure resistance were tested by inserting test tissue into the gastrointestinal tract. All results met the standard requirements. The in vivo degradation period was also tested through animal experiments. The results are shown in the table below. Serial Number Magnesium alloy composition Tensile strength / MPa Yield strength / MPa Elongation / % In vivo degradation cycle / day 1 Mg + 1.6Al + 1.5Zn + 0.8Mn + 0.2Ca 300 270 14 180 2 Mg + 1.8Al + 1.5Zn + 0.8Mn + 0.2Ca 310 275 15 180 3 Mg + 1.6Al + 1.5Zn + 0.5Mn + 0.25Ca 285 262 12 180

[0032] The above examples demonstrate that by optimizing the proportions of the various components of the magnesium alloy and controlling the molding process parameters, the processed magnesium alloy staples meet the requirements for the mechanical properties of the soft tissue within the anastomosis and the requirements for wound healing.

[0033] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the invention disclosed in the specification and embodiments. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the claims.

[0034] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A biodegradable anastomotic staple, the staple having a U-shaped structure, including a crossbeam and two staple legs located at both ends of the crossbeam; the staple is made of magnesium alloy, the composition of which, by weight percentage, is: 1-2% Al, 1-1.5% Zn, 0.5-1.2% Mn, 0.1-0.6% Ca, with the balance being Mg; the staple is made of magnesium alloy wire, the diameter of which is also the diameter of the staple is 0.2mm-0.6mm.

2. The anastomosis staple as described in claim 1, characterized in that, The diameter is 0.23 mm.

3. The anastomotic staple as described in claim 1, characterized in that, The angle between the nail leg and the crossbeam is 90°-100°, the length of the crossbeam is 2.6mm-10mm, and the height of the nail leg is 2.0mm~5.5mm.

4. The stapler as described in any one of claims 1-3, characterized in that, The top of the spike leg is designed with a sloping structure, with an included angle of 30°~40°.

5. The method for preparing the anastomotic staple according to any one of claims 1-4, characterized in that, Various metals are mixed and smelted into liquid metal, the slag is removed, and the mixture is cast into magnesium alloy ingots. The magnesium alloy ingots are then heat-treated and subjected to multiple extrusion and drawing processes to produce wire. The wire is then annealed to produce staples.

6. The method for preparing the anastomotic staple as described in claim 5, characterized in that, Under argon protection, an alloy containing 1-2% Al, 1-1.5% Zn, 0.5-1.2% Mn, 0.1-0.6% Ca, and the balance Mg by weight is melted into a liquid metal at a high temperature of 650℃-1250℃. After standing and filtering to remove slag, the molten metal is cast into magnesium alloy ingots. After heat treatment at 400℃ for 8 hours, it undergoes multiple extrusion drawing at a temperature of 350℃, with a single-pass deformation of 20%-30% and a drawing speed of 20 mm / s. Finally, wires with a diameter of 0.2-0.6 mm are produced and annealed at 200℃ for 60 minutes. The obtained magnesium alloy wires are then processed into staples using a staple-making machine.

7. The method for preparing the anastomotic staple as described in claim 6, characterized in that, It is melted into liquid metal at high temperatures of 660℃-850℃.

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