A method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis

Abstract

The present invention provides a method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis, comprising: making a shape memory alloy sheet into a shape memory alloy wire based on a metal drawing process; winding the shape memory alloy wire into a shape memory alloy spring through a spring making process; winding the shape memory alloy spring into a quasi-cylindrical elastomer in a cylindrical cavity of a first mold by a flat stacking winding method; pressing, heating, and heat-insulating the quasi-cylindrical elastomer in sequence to form a solid quasi-cylindrical elastomer; pressing, heating, and heat-insulating the solid quasi-cylindrical elastomer in sequence to form a second elliptical cylindrical nucleus pulposus prosthesis, wherein the porosity of the second elliptical cylindrical nucleus pulposus prosthesis is greater than 80%; and after cooling the second elliptical cylindrical nucleus pulposus prosthesis, pressing it with a deformation amount of not less than 30% to form a shape memory alloy artificial nucleus pulposus prosthesis. The method solves the technical problems of artificial nucleus pulposus prostheses in the prior art, such as large elastic modulus, poor mechanical properties, poor antioxidant ability, poor wear resistance, and large volume.

Description

Technical Field

[0001] The present invention relates to the technical field of medical implant devices, and in particular to a method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis. Background Art

[0002] In modern society, most people spend long periods of time in front of computers, leading to an increasing incidence of lumbar disc herniation. Lumbar disc herniation primarily refers to a series of symptoms caused by rupture of the annulus fibrosus and bulging of the nucleus pulposus, which compresses and irritates one or both sciatic nerves at the corresponding level.

[0003] Nucleus pulposus replacement is an effective method for treating lumbar disc herniation, and the ideal artificial nucleus pulposus must meet the following requirements: 1. It has good biocompatibility and biodurability, will not degrade or produce rejection reactions in the body, and has low wear and low consumption; 2. The stiffness and mobility of the prosthesis are within the normal physiological range, and can withstand endurance fatigue tests and will not be squeezed out in the body; 3. It can resist stress, maintain the height of the intervertebral space and have a buffering effect; 4. It has good compliance, moderate hardness, and can maintain its shape while evenly transmitting stress; 5. It is easy to implant, with a shape and size that matches the normal nucleus pulposus space; 6. It has a liquid pump function, which can increase the nutrient supply to the remaining nucleus pulposus and the inner annulus fibrosus, so that the annulus fibrosus maintains its biomechanical strength.

[0004] At present, artificial nucleus pulposus prostheses still have the following problems: first, the elastic modulus is too high, which affects the patient's daily life; second, the manufacturing material is high molecular polymer, which leads to poor mechanical properties, antioxidant ability and wear resistance of the artificial nucleus pulposus prosthesis. Long-term use cannot guarantee the effectiveness of use and easily produces debris, causing pain to patients; third, the artificial nucleus pulposus prosthesis is large in size and easily damages the annulus fibrosus during surgical implantation. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis, so as to solve the technical problems of artificial nucleus pulposus prosthesis in the prior art, such as large elastic modulus, poor mechanical properties, poor antioxidant ability, poor wear resistance and large size.

[0006] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0007] A method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis is provided, and the method comprises the following steps:

[0008] Based on the metal drawing process, the shape memory alloy sheet is made into a shape memory alloy wire with a desired diameter;

[0009] Through a spring making process, the shape memory alloy wire is wound into a shape memory alloy spring;

[0010] A shape memory alloy spring is wound into a quasi-cylindrical elastic body in a cylindrical cavity of a first mold by a flat superposition winding method, wherein the flat superposition winding method is as follows: the first end of the shape memory alloy spring is flatly laid on the center of the bottom surface of the cylindrical cavity, the second end of the shape memory alloy spring is wound in a quasi-helical shape toward the cavity wall of the cylindrical cavity with the central axis of the cylindrical cavity as the center, until the shape memory alloy spring covers the bottom surface of the cylindrical cavity to form a first flat spring layer, the second end of the shape memory alloy spring is raised and wound inward in a quasi-helical shape along the cavity wall of the cylindrical cavity toward the central axis of the cylindrical cavity until a second flat spring layer is formed, and the above winding process is repeated until the shape memory alloy spring is wound to form an Nth flat spring layer, where N is a natural number greater than 1, and the plurality of spring coils of the upper flat spring layer are all located in the middle of the plurality of pitch spaces of the lower flat spring layer, and the N layers of the flat spring layers constitute the quasi-cylindrical elastic body;

[0011] placing the first mold and the quasi-cylindrical elastomer into a stamping device, pressing the quasi-cylindrical elastomer into a preliminary solid quasi-cylindrical elastomer, placing the preliminary solid quasi-cylindrical elastomer and the first mold together in an air furnace, heating to 37° C. and keeping the temperature to shape into a solid quasi-cylindrical elastomer;

[0012] placing the solid cylindrical elastic body into the elliptical cylindrical cavity of the second mold, and using the punching equipment to press the solid cylindrical elastic body into a first elliptical cylindrical nucleus pulposus prosthesis;

[0013] placing the first elliptical cylindrical nucleus pulposus prosthesis and the second mold together in the air furnace, heating to 37° C. and keeping the temperature to shape into a second elliptical cylindrical nucleus pulposus prosthesis, wherein the porosity of the second elliptical cylindrical nucleus pulposus prosthesis is greater than 80%;

[0014] The second elliptical cylindrical nucleus pulposus prosthesis is cooled by liquid nitrogen, and is pressed into a shape memory alloy artificial nucleus pulposus prosthesis by the punching device with a set deformation amount, wherein the set deformation amount is not less than 30%.

[0015] In a method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis according to an embodiment of the present application, the method of manufacturing a shape memory alloy sheet into a shape memory alloy wire having a desired diameter based on a metal drawing process includes the following steps:

[0016] Placing the shape memory alloy plate in the air furnace, setting the temperature of the air furnace to 900° C., solution treating the plate for 2 hours, and performing wire cutting on the solution treated shape memory alloy plate to obtain a first shape memory alloy wire with a diameter of 0.8 mm;

[0017] Immersing the first end of the first shape memory alloy wire in a corrosion solution at a uniform speed for 5-30 minutes to obtain a second shape memory alloy wire, wherein the corrosion solution is a mixed solution of hydrofluoric acid, nitric acid, and water, and the ratio of the hydrofluoric acid, nitric acid, and water is 1:4:20;

[0018] The second shape memory alloy wire is subjected to several cold drawing and slitting processes using a drawing device to obtain a shape memory alloy wire having a desired diameter, wherein the deformation of the second shape memory alloy wire is less than 20% in each cold drawing process, and after each cold drawing process, the second shape memory alloy wire is subjected to an annealing stress relief treatment at 400° C. for 2 minutes.

[0019] In the method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis described in an embodiment of the present application, the drawing device includes a diameter reducing device, a front straightening device, a drawing die, a traction device, a rear straightening device and a slitting device;

[0020] The diameter-changing device is used to unify the diameter of the second shape memory alloy wire;

[0021] The front straightening device is used to perform a first straightening on the second shape memory alloy wire;

[0022] The drawing die is used to provide a through-die hole for the second shape memory alloy wire, and the through-die hole is used to change the diameter of the second shape memory alloy wire when the second shape memory alloy wire is subjected to a cold drawing process;

[0023] The pulling device is used to clamp and draw one end of the second shape memory alloy wire passing through the drawing die;

[0024] The slitting device is used to cut the second shape memory alloy wire that has been subjected to multiple cold drawing processes to reach an expected diameter, so as to obtain the shape memory alloy wire that meets the expected diameter.

[0025] In the method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis described in an embodiment of the present application, the spring-making process of winding the shape memory alloy wire into a shape memory alloy spring includes the following steps:

[0026] Using an automatic spring winding machine, winding the shape memory alloy wire on a spring winding die to form a primary shape memory alloy spring;

[0027] The primary shape memory alloy spring and the spring winding mold are placed together in the air furnace, heated to 37° C. and kept warm to form the shape memory alloy spring.

[0028] In the method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis according to an embodiment of the present application, before cooling the second elliptical cylindrical nucleus pulposus prosthesis using liquid nitrogen and pressing the second elliptical cylindrical nucleus pulposus prosthesis into a shape memory alloy artificial nucleus pulposus prosthesis with a set deformation amount using the stamping equipment, the method further includes:

[0029] The structural mechanical properties of the second elliptical cylindrical nucleus pulposus prosthesis were measured using a tensile testing machine.

[0030] In the method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis described in an embodiment of the present application, the diameter of the shape memory alloy wire that meets the expected diameter is defined as D, and D≤0.7 mm is satisfied.

[0031] In the method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis described in an embodiment of the present application, the spring pitch of the shape memory alloy spring is defined as h, and h satisfies 0.4 mm ≤ h ≤ 0.6 mm.

[0032] In the method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis described in an embodiment of the present application, the height of the second elliptical cylindrical nucleus pulposus prosthesis is defined as H, and H satisfies 5mm≤H≤9mm.

[0033] In the method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis described in an embodiment of the present application, the short axis length of the elliptical cylindrical cavity of the second mold is 12 mm, and the long axis length of the elliptical cylindrical cavity of the second mold is 25 mm.

[0034] In the manufacturing method of a shape memory alloy artificial nucleus pulposus prosthesis described in an embodiment of the present application, the material of the shape memory alloy plate is one of titanium-nickel alloy, titanium-nickel-zirconium alloy, titanium-nickel-hafnium alloy, titanium-nickel-iron alloy, titanium-nickel-copper alloy, titanium-nickel-copper-aluminum alloy, copper-aluminum-manganese alloy, copper-aluminum-nickel alloy, copper-zinc-aluminum alloy, iron-nickel-cobalt-titanium alloy, iron-nickel-cobalt-aluminum alloy or iron-manganese-silicon alloy.

[0035] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0036] It can be seen from the above technical scheme that the embodiment of the present application provides a method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis. By using shape memory alloy to manufacture the artificial nucleus pulposus prosthesis, the technical problem in the prior art that the mechanical properties, oxidation resistance and wear resistance of the artificial nucleus pulposus prosthesis are poor due to the material of the artificial nucleus pulposus prosthesis being a high molecular polymer is solved. The shape memory alloy spring is wound into a quasi-cylindrical elastomer in the cylindrical cavity of the first mold by a flat superposition winding method, and the quasi-cylindrical elastomer is made into a solid quasi-cylindrical elastomer by using a stamping device and an air furnace. The solid quasi-cylindrical elastomer is made into a second elliptical cylindrical nucleus pulposus prosthesis by using a stamping device, a second mold and an air furnace. The porosity of the second elliptical cylindrical nucleus pulposus prosthesis is greater than 80%, which solves the technical problem of the artificial nucleus pulposus prosthesis in the prior art that the elastic modulus is too high. The second elliptical cylindrical nucleus pulposus prosthesis is pressed into a smaller shape memory alloy artificial nucleus pulposus prosthesis by cooling and compressing, which solves the technical problem in the prior art that the artificial nucleus pulposus prosthesis is large in size and easily damages the annulus fibrosus during surgical implantation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief introduction to the drawings required for the description of the embodiments. The drawings are not intended to be drawn to scale, and for the sake of clarity, not every component will be labeled in each figure. The drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without inventive work. Among them:

[0038] Figure 1 This is a flow chart of a method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis according to an embodiment of the present application.

[0039] Figure 2 This is a finished product picture of the shape memory alloy artificial nucleus pulposus prosthesis according to an embodiment of the present application.

[0040] Figure 3 Schematic diagram of the center connection lines of several spring coils of the flat spring layer according to an embodiment of the present application.

[0041] Figure 4 This is a schematic structural diagram of a shape memory alloy artificial nucleus pulposus prosthesis implanted into the annulus fibrosus of an intervertebral disc according to an embodiment of the present application.

[0042] Figure 5 This is a schematic structural diagram of the drawing equipment according to an embodiment of the present application.

[0043] Figure 6 This is a schematic structural diagram of the second mold of an embodiment of the present application.

[0044] Figure 7This is a load-displacement curve diagram of the second elliptical cylindrical nucleus pulposus prosthesis according to an embodiment of the present application.

[0045] Figure 8 FIG. 1 is a stress-strain curve diagram of the second elliptical cylindrical nucleus pulposus prosthesis according to an embodiment of the present application.

[0046] Description of reference numerals:

[0047] 110-Vertebral body 120-Annulus fibrosus 130-Shape memory alloy artificial nucleus pulposus prosthesis

[0048] 210-diameter reducing device 220-front straightening device 230-drawing die

[0049] 240-Post-straightening device 250-Slitting device

[0050] 310- Center lines of several spring coils in a flat spring layer

[0051] 410- front of mold 420- rear of mold DETAILED DESCRIPTION

[0052] The embodiment of the present application provides a method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis to manufacture a shape memory alloy artificial nucleus pulposus prosthesis, which can solve the technical problems of artificial nucleus pulposus prostheses in the prior art, such as large elastic modulus, poor mechanical properties, poor antioxidant ability, poor wear resistance and large size.

[0053] In view of this, the concept of the embodiment of the present application is to use shape memory alloy to make an artificial nucleus pulposus prosthesis, thereby solving the technical problem in the prior art that the artificial nucleus pulposus prosthesis is made of a high molecular polymer, resulting in poor mechanical properties, oxidation resistance and wear resistance of the artificial nucleus pulposus prosthesis. The shape memory alloy spring is wound into a quasi-cylindrical elastomer in the cylindrical cavity of the first mold by a flat overlapping winding method, and the quasi-cylindrical elastomer is made into a solid quasi-cylindrical elastomer by using a stamping equipment and an air furnace. The solid quasi-cylindrical elastomer is made into a second elliptical cylindrical nucleus pulposus prosthesis by using a stamping equipment, a second mold and an air furnace. The porosity of the second elliptical cylindrical nucleus pulposus prosthesis is greater than 80%, which solves the technical problem in the prior art that the elastic modulus of the artificial nucleus pulposus prosthesis is too high. The second elliptical cylindrical nucleus pulposus prosthesis is pressed into a smaller shape memory alloy artificial nucleus pulposus prosthesis by cooling and compressing, which solves the technical problem in the prior art that the artificial nucleus pulposus prosthesis is large in size, which makes the annulus fibrosus easily damaged during surgical implantation.

[0054] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0055] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply 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 application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0056] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0057] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0058] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art will appreciate the application of other processes and / or the use of other materials.

[0059] The present invention provides a method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis. Figures 1 to 8 As shown, a method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis is used to manufacture a shape memory alloy artificial nucleus pulposus prosthesis, and the method comprises the following steps:

[0060] Step S10: Based on a metal drawing process, the shape memory alloy sheet is made into a shape memory alloy wire having a desired diameter.

[0061] In certain embodiments, the step of forming a shape memory alloy wire having a desired diameter from a shape memory alloy sheet using a metal drawing process comprises the following steps:

[0062] Step S101: placing the shape memory alloy plate in the air furnace, setting the temperature of the air furnace to 900° C., performing solution treatment for 2 hours, and performing wire cutting on the solution treated shape memory alloy plate to obtain a first shape memory alloy wire with a diameter of 0.8 mm.

[0063] Among them, the material of the shape memory alloy plate is one of titanium-nickel alloy, titanium-nickel-zirconium alloy, titanium-nickel-hafnium alloy, titanium-nickel-iron alloy, titanium-nickel-copper alloy, titanium-nickel-copper-aluminum alloy, copper-aluminum-manganese alloy, copper-aluminum-nickel alloy, copper-zinc-aluminum alloy, iron-nickel-cobalt-titanium alloy, iron-nickel-cobalt-aluminum alloy or iron-manganese-silicon alloy. Preferably, the material of the shape memory alloy plate is titanium-nickel alloy, which has more stable performance. The titanium-nickel alloy includes the following components by mass percentage: titanium-44%, nickel-56%. The thickness of the shape memory alloy plate is 1.5 mm.

[0064] Step S102: immersing the first end of the first shape memory alloy wire into a corrosive solution at a uniform speed for 5-30 minutes to obtain a second shape memory alloy wire.

[0065] The corrosive liquid is used to corrode impurities on the surface of the first end of the first shape memory alloy wire and clean the surface. The corrosive liquid is a mixed solution of hydrofluoric acid, nitric acid and water. The ratio of hydrofluoric acid, nitric acid and water is 1:4:20. The length of the first end of the first shape memory alloy wire is 20 mm to 50 mm. Preferably, the immersion time is 20 minutes. The first end of the second shape memory alloy wire is the end cleaned by the corrosive liquid.

[0066] Step S103: Using a drawing device, the second shape memory alloy wire is subjected to several cold drawing processes and one slitting process to obtain a shape memory alloy wire having an expected diameter, wherein in each cold drawing process of the second shape memory alloy wire, the deformation of the second shape memory alloy wire is less than 20%, and after each cold drawing process, the second shape memory alloy wire is subjected to an annealing stress relief treatment at 400°C / 2 min.

[0067] Specifically, the drawing equipment includes a diameter reducing device 210, a front straightening device 220, a drawing die 230, a traction device, a rear straightening device 240 and a slitting device 250. The diameter reducing device 210, the front straightening device 220, the drawing die 230, the rear straightening device 240 and the slitting device 250 are distributed in a straight line. When in use, the first end of the second shape memory alloy wire is passed through the diameter reducing device 210. The diameter reducing device 210 is used to unify the diameter of the second shape memory alloy wire. After the second shape memory alloy wire passes through the diameter reducing device 210, it enters and passes through the front straightening device 220. The front straightening device The straightening device 220 is used to straighten the second shape memory alloy wire for the first time. After passing through the front straightening device 220, the second shape memory alloy wire passes through the through-die hole of the drawing die 230. The drawing die 230 is used to provide the through-die hole for the second shape memory alloy wire. When the second shape memory alloy wire is cold drawn, the through-die hole is used to change the diameter of the second shape memory alloy wire. The pulling device is used to clamp and pull the first end of the second shape memory alloy wire passing through the through-die hole of the drawing die 230 until the second shape memory alloy wire is completely straightened. The second shape memory alloy wire after drawing is passed through the drawing die 230, and passes through the rear straightening device 240. The rear straightening device 240 is used to perform a second straightening on the second shape memory alloy wire after drawing. The slitting device 250 is used to cut the second shape memory alloy wire that has reached the expected diameter after multiple cold drawing processes to obtain the shape memory alloy wire that meets the expected diameter. Each time the second shape memory alloy wire is cold drawn, it passes through the diameter reducing device 210, the front straightening device 220, the drawing die 230, the traction equipment and the rear straightening device 240, and the second shape memory alloy wire After each cold drawing process of the second shape memory alloy wire, the second shape memory alloy wire is placed in the air furnace for annealing and stress relief treatment at 400°C / 2 minutes to prevent the second shape memory alloy wire from generating microcracks and wire breakage during the next cold drawing process. After the last cold drawing process is completed and the annealing and stress relief treatment at 400°C / 2 minutes is performed to obtain the second shape memory alloy wire with the expected diameter, the slitting device 250 cuts the second shape memory alloy wire with the expected diameter to obtain a shape memory alloy wire with the expected diameter.

[0068] Among them, the diameter of the shape memory alloy wire that meets the expected diameter is D, and D≤0.7mm, to avoid the diameter of the shape memory alloy wire being too large, which leads to an excessively large elastic modulus of the shape memory alloy artificial nucleus pulposus prosthesis. Preferably, D can be 0.3mm, 0.5mm, or 0.7mm.

[0069] Step S20: Winding the shape memory alloy wire into a shape memory alloy spring through a spring making process.

[0070] In certain embodiments, the spring-making process of winding the shape memory alloy wire into a shape memory alloy spring includes the following steps:

[0071] Step S201: using an automatic spring winding machine to wind the shape memory alloy wire on a spring winding die to form a primary shape memory alloy spring.

[0072] Step S202: placing the primary shape memory alloy spring and the spring winding mold together in the air furnace, heating them to 37° C. and keeping them warm to shape them into the shape memory alloy spring.

[0073] In which, the primary shape memory alloy spring is kept warm in the air furnace for 10-30 minutes, the spring middle diameter of the shape memory alloy spring is 5 mm, the spring pitch of the shape memory alloy spring is h, and the h satisfies 0.4 mm ≤ h ≤ 0.6 mm. If the h is too small, the elastic modulus of the shape memory alloy artificial nucleus pulposus prosthesis is too large, and if the h is too large, the structure of the shape memory alloy artificial nucleus pulposus prosthesis is too loose. Preferably, the h can be 0.4 mm, 0.5 mm, or 0.6 mm. The number of coils of the shape memory alloy spring is M. This embodiment provides three preferred options of the shape memory alloy springs. When the D is 0.3 mm, the h is 0.4 mm, and the M is 100 coils. When the D is 0.5 mm, the h is 0.5 mm, and the M is 120 coils. When the D is 0.7 mm, the h is 0.6 mm, and the M is 140 coils.

[0074] Step S30: Winding the shape memory alloy spring into a cylindrical elastic body in the cylindrical cavity of the first mold by a flat superposition winding method, wherein the flat superposition winding method is as follows: the first end of the shape memory alloy spring is flatly laid on the center of the bottom surface of the cylindrical cavity, and the second end of the shape memory alloy spring is wound in a spiral shape toward the cavity wall of the cylindrical cavity with the central axis of the cylindrical cavity as the center, until the shape memory alloy spring covers the bottom surface of the cylindrical cavity to form a first layer of flat elastic body. The spring layer is formed by raising the second end of the shape memory alloy spring and winding it inward in a spiral shape along the wall of the cylindrical cavity toward the central axis of the cylindrical cavity until a second flat spring layer is formed. The above winding process is repeated until the shape memory alloy spring is wound to form an Nth flat spring layer, where N is a natural number greater than 1, and the multiple spring coils of the upper flat spring layer are all located in the middle of the multiple pitch spaces of the lower flat spring layer. The N layers of the flat spring layers constitute the quasi-cylindrical elastomer.

[0075] The center line 310 of the plurality of spring coils of each flat spring layer is spiral-shaped, and the plane in which it is located is parallel to the bottom surface of the cylindrical cavity. The diameter of the cylindrical cavity is 20 mm. The pitch space refers to the space between any two adjacent spring coils in the shape memory alloy spring. In this embodiment, preferably, N can be 2 or 3. When the number M of spring coils of the shape memory alloy spring is 100, N is 2. The flat superposition winding method is specifically as follows: the first end of the shape memory alloy spring is flatly laid on the center of the bottom surface of the cylindrical cavity, and the second end of the shape memory alloy spring is flatly laid on the bottom surface of the cylindrical cavity. The central axis of the cylindrical cavity is taken as the center and the spring is wound in a quasi-helical shape toward the cavity wall of the cylindrical cavity until the shape memory alloy spring covers the bottom surface of the cylindrical cavity to form a first flat spring layer. The second end of the shape memory alloy spring is raised and wound inward in a quasi-helical shape along the cavity wall of the cylindrical cavity toward the central axis of the cylindrical cavity until a second flat spring layer is formed. The plurality of spring coils of the second flat spring layer are all located in the middle of the plurality of pitch spaces of the first flat spring layer. The first flat spring layer and the second flat spring layer constitute the quasi-cylindrical elastic body. When the spring coils of the shape memory alloy spring When the number M is 120 turns or 140 turns, N is 3, and the flat superposition winding method is specifically as follows: the first end of the shape memory alloy spring is flatly laid on the center of the bottom surface of the cylindrical cavity, and the second end of the shape memory alloy spring is wound in a spiral shape toward the cavity wall of the cylindrical cavity with the central axis of the cylindrical cavity as the center, until the shape memory alloy spring covers the bottom surface of the cylindrical cavity to form a first flat spring layer, the second end of the shape memory alloy spring is raised and wound inward in a spiral shape along the cavity wall of the cylindrical cavity toward the central axis of the cylindrical cavity until a second flat spring layer is formed, and the shape memory alloy spring is wound in a spiral shape. The second end of the shape memory alloy spring continues to rise upward, and is wound in a spiral shape toward the cavity wall of the cylindrical cavity from the central axis of the cylindrical cavity with the central axis of the cylindrical cavity as the center, until the shape memory alloy spring is wound to form a third flat spring layer. The several spring coils of the third flat spring layer are all located in the middle of the several pitch spaces of the second flat spring layer, and the several spring coils of the second flat spring layer are all located in the middle of the several pitch spaces of the first flat spring layer. The first flat spring layer, the second flat spring layer and the third flat spring layer constitute the quasi-cylindrical elastomer.

[0076] Step S40: Place the first mold and the cylindrical elastomer into a stamping device, press the cylindrical elastomer into a preliminary solid cylindrical elastomer, place the preliminary solid cylindrical elastomer and the first mold together in an air furnace, heat them to 37°C and keep them warm to shape them into a solid cylindrical elastomer.

[0077] In which, the preliminary solid cylindrical elastomer is kept warm in the air furnace for 10-30 minutes, preferably 20 minutes, and the stamping equipment is a precision press. When the D is 0.3 mm, the h is 0.4 mm, and the M is 100 turns, the height of the solid cylindrical elastomer is 8 mm. When the D is 0.5 mm, the h is 0.5 mm, and the M is 120 turns, the height of the solid cylindrical elastomer is 10 mm. When the D is 0.7 mm, the h is 0.6 mm, and the M is 140 turns, the height of the solid cylindrical elastomer is 12 mm.

[0078] Step S50: placing the solid cylindrical elastomer into the elliptical cylindrical cavity of the second mold, and using the punching equipment to press the solid cylindrical elastomer into a first elliptical cylindrical nucleus pulposus prosthesis.

[0079] Among them, the second mold includes a mold front part 410 and a mold rear part 420, and the mold front part 410 and the mold rear part 420 are detachably connected. The end of the mold front part 410 close to the mold rear part 420 and the end of the mold rear part 420 close to the mold front 410 are both provided with semi-elliptical grooves. When the mold front part 410 and the mold rear part 420 are fitted together, the two semi-elliptical grooves form an elliptical cylindrical cavity of the second mold. The short axis length of the elliptical cylindrical cavity of the second mold is 12 mm, and the long axis length of the elliptical cylindrical cavity of the second mold is 25 mm. When in use, first separate the front part 410 of the mold and the rear part 420 of the mold, place the solid cylindrical elastomer in the middle of the front part 410 and the rear part 420 of the mold, close the front part 410 and the rear part 420 of the mold to form a first elliptical cylindrical nucleus pulposus prosthesis with an uncompressed height, and place the first elliptical cylindrical nucleus pulposus prosthesis with an uncompressed height and the second mold into the stamping equipment to press it into the first elliptical cylindrical nucleus pulposus prosthesis.

[0080] Step S60: placing the first elliptical cylindrical nucleus pulposus prosthesis and the second mold together in the air furnace, heating to 37° C. and keeping the temperature to shape into a second elliptical cylindrical nucleus pulposus prosthesis, wherein the porosity of the second elliptical cylindrical nucleus pulposus prosthesis is greater than 80%.

[0081] In which, the first elliptical cylindrical nucleus pulposus prosthesis is kept warm in the air furnace for 10-30 minutes, the height of the second elliptical cylindrical nucleus pulposus prosthesis is H, and the H satisfies 5mm≤H≤9mm. Preferably, when the height of the solid cylindrical elastomer is 8mm, the height of the second elliptical cylindrical nucleus pulposus prosthesis is 5mm, when the height of the solid cylindrical elastomer is 10mm, the height of the second elliptical cylindrical nucleus pulposus prosthesis is 7mm, and when the height of the solid cylindrical elastomer is 12mm, the height of the second elliptical cylindrical nucleus pulposus prosthesis is 9mm, to correspond to different patients with lumbar disc heights of 5mm~7mm, 7mm~9mm and above 9mm.

[0082] Step S70: Using a tensile testing machine, measuring the structural mechanical properties of the second elliptical cylindrical nucleus pulposus prosthesis.

[0083] Among them, in this embodiment, taking the second elliptical cylindrical nucleus pulposus prosthesis with a height of 7 mm as an example, the maximum recoverable strain of the second elliptical cylindrical nucleus pulposus prosthesis is 45%, the stiffness is 2.1N / mm~3.07N / mm, and the elastic modulus is 1.47MPa~2.16MPa. Subsequently, tests are conducted when the strain of the second elliptical cylindrical nucleus pulposus prosthesis is 15%, 25%, 35% and 45%, respectively. Combined with the experimental data, the following is obtained: Figure 7 The load-displacement curve of the second elliptical cylindrical nucleus pulposus prosthesis shown in FIG. Figure 8 The stress-strain curve diagram of the second elliptical cylindrical nucleus pulposus prosthesis is shown.

[0084] Step S80: using liquid nitrogen to cool the second elliptical cylindrical nucleus pulposus prosthesis, and pressing the second elliptical cylindrical nucleus pulposus prosthesis into a shape memory alloy artificial nucleus pulposus prosthesis with a set deformation amount by the stamping equipment, wherein the set deformation amount is not less than 30%.

[0085] In this embodiment, the second elliptical cylindrical nucleus pulposus prosthesis does not need to be removed from the second mold. The second elliptical cylindrical nucleus pulposus prosthesis and the second mold are directly cooled to 15°C. The second elliptical cylindrical nucleus pulposus prosthesis and the second mold are then placed in a stamping machine. The deformation of the second elliptical cylindrical nucleus pulposus prosthesis is set to 30%, and the stamping machine is started to press the second elliptical cylindrical nucleus pulposus prosthesis into a shape memory alloy artificial nucleus pulposus prosthesis. The shape memory alloy artificial nucleus pulposus prosthesis is stored in an environment below 37°C. Based on the one-way memory effect of the shape memory alloy, the second elliptical cylindrical nucleus pulposus prosthesis is pressed into a smaller shape memory alloy artificial nucleus pulposus prosthesis through cooling and compression. The reduced volume of the artificial nucleus pulposus prosthesis facilitates surgical implantation without damaging the annulus fibrosus. After the shape memory alloy artificial nucleus pulposus prosthesis is implanted in the human body, the temperature of the shape memory alloy artificial nucleus pulposus prosthesis gradually reaches the human body temperature of 37°C. The shape memory alloy artificial nucleus pulposus prosthesis transforms from martensite to an austenite parent phase, and the shape of the shape memory alloy artificial nucleus pulposus prosthesis returns to the shape of the second elliptical cylindrical nucleus pulposus prosthesis, meeting the patient's usage requirements.

[0086] In summary, the embodiment of the present application provides a method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis. By using shape memory alloy to manufacture the artificial nucleus pulposus prosthesis, the technical problem in the prior art that the artificial nucleus pulposus prosthesis is made of a high molecular polymer, resulting in poor mechanical properties, oxidation resistance and wear resistance of the artificial nucleus pulposus prosthesis. The shape memory alloy spring is wound into a quasi-cylindrical elastomer in the cylindrical cavity of the first mold by a flat overlapping winding method, the quasi-cylindrical elastomer is made into a solid quasi-cylindrical elastomer by using a stamping device and an air furnace, and the solid quasi-cylindrical elastomer is made into a second elliptical cylindrical nucleus pulposus prosthesis by using a stamping device, a second mold and an air furnace. The porosity of the second elliptical cylindrical nucleus pulposus prosthesis is greater than 80%, which solves the technical problem in the prior art that the elastic modulus of the artificial nucleus pulposus prosthesis is too high. The second elliptical cylindrical nucleus pulposus prosthesis is pressed into a smaller shape memory alloy artificial nucleus pulposus prosthesis by cooling and compressing, which solves the technical problem in the prior art that the artificial nucleus pulposus prosthesis is large in size, which makes the annulus fibrosus easily damaged during surgical implantation.

[0087] The above is a detailed introduction to the method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis provided in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis, which is used to manufacture a shape memory alloy artificial nucleus pulposus prosthesis, characterized in that: The method comprises the following steps: Based on the metal drawing process, the shape memory alloy sheet is made into a shape memory alloy wire with a desired diameter; Through a spring making process, the shape memory alloy wire is wound into a shape memory alloy spring; A shape memory alloy spring is wound into a quasi-cylindrical elastic body in a cylindrical cavity of a first mold by a flat superposition winding method, wherein the flat superposition winding method is as follows: the first end of the shape memory alloy spring is flatly laid on the center of the bottom surface of the cylindrical cavity, the second end of the shape memory alloy spring is wound in a quasi-helical shape toward the cavity wall of the cylindrical cavity with the central axis of the cylindrical cavity as the center, until the shape memory alloy spring covers the bottom surface of the cylindrical cavity to form a first flat spring layer, the second end of the shape memory alloy spring is raised and wound inward in a quasi-helical shape along the cavity wall of the cylindrical cavity toward the central axis of the cylindrical cavity until a second flat spring layer is formed, and the above winding process is repeated until the shape memory alloy spring is wound to form an Nth flat spring layer, where N is a natural number greater than 1, and the plurality of spring coils of the upper flat spring layer are all located in the middle of the plurality of pitch spaces of the lower flat spring layer, and the N layers of the flat spring layers together constitute the quasi-cylindrical elastic body; placing the first mold and the quasi-cylindrical elastomer into a stamping device, pressing the quasi-cylindrical elastomer into a preliminary solid quasi-cylindrical elastomer, placing the preliminary solid quasi-cylindrical elastomer and the first mold together in an air furnace, heating to 37° C. and keeping the temperature to shape into a solid quasi-cylindrical elastomer; placing the solid cylindrical elastic body into the elliptical cylindrical cavity of the second mold, and using the punching equipment to press the solid cylindrical elastic body into a first elliptical cylindrical nucleus pulposus prosthesis; placing the first elliptical cylindrical nucleus pulposus prosthesis and the second mold together in the air furnace, heating to 37° C. and keeping the temperature to shape into a second elliptical cylindrical nucleus pulposus prosthesis, wherein the porosity of the second elliptical cylindrical nucleus pulposus prosthesis is greater than 80%; The second elliptical cylindrical nucleus pulposus prosthesis is cooled by liquid nitrogen, and is pressed into a shape memory alloy artificial nucleus pulposus prosthesis by the punching device with a set deformation amount, wherein the set deformation amount is not less than 30%.

2. The method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis according to claim 1, characterized in that: The method of manufacturing a shape memory alloy wire having a desired diameter from a shape memory alloy sheet based on a metal drawing process comprises the following steps: Placing the shape memory alloy plate in the air furnace, setting the temperature of the air furnace to 900° C., solution treating the plate for 2 hours, and performing wire cutting on the solution treated shape memory alloy plate to obtain a first shape memory alloy wire with a diameter of 0.8 mm; Immersing the first end of the first shape memory alloy wire in a corrosion solution at a uniform speed for 5-30 minutes to obtain a second shape memory alloy wire, wherein the corrosion solution is a mixed solution of hydrofluoric acid, nitric acid, and water, and the ratio of the hydrofluoric acid, nitric acid, and water is 1:4:20; The second shape memory alloy wire is subjected to several cold drawing and slitting processes using a drawing device to obtain a shape memory alloy wire having a desired diameter, wherein the deformation of the second shape memory alloy wire is less than 20% in each cold drawing process, and after each cold drawing process, the second shape memory alloy wire is subjected to an annealing stress relief treatment at 400° C. for 2 minutes.

3. The method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis according to claim 2, characterized in that: The drawing equipment includes a diameter reducing device, a front straightening device, a drawing die, a pulling device, a rear straightening device and a slitting device; The diameter-changing device is used to unify the diameter of the second shape memory alloy wire; The front straightening device is used to perform a first straightening on the second shape memory alloy wire; The drawing die is used to provide a through-die hole for the second shape memory alloy wire, and the through-die hole is used to change the diameter of the second shape memory alloy wire when the second shape memory alloy wire is subjected to a cold drawing process; The pulling device is used to clamp and draw one end of the second shape memory alloy wire passing through the drawing die; The slitting device is used to cut the second shape memory alloy wire that has been subjected to multiple cold drawing processes to reach an expected diameter, so as to obtain the shape memory alloy wire that meets the expected diameter.

4. The method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis according to claim 1, wherein: The spring making process of winding the shape memory alloy wire into a shape memory alloy spring comprises the following steps: Using an automatic spring winding machine, winding the shape memory alloy wire on a spring winding die to form a primary shape memory alloy spring; The primary shape memory alloy spring and the spring winding mold are placed together in the air furnace and heated to 37° C. and kept warm to form the shape memory alloy spring.

5. The method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis according to claim 1, characterized in that: Before cooling the second elliptical cylindrical nucleus pulposus prosthesis by using liquid nitrogen and pressing the second elliptical cylindrical nucleus pulposus prosthesis into a shape memory alloy artificial nucleus pulposus prosthesis with a set deformation amount by using the stamping equipment, the method further includes: The structural mechanical properties of the second elliptical cylindrical nucleus pulposus prosthesis were measured using a tensile testing machine.

6. The method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis according to claim 1, wherein: The diameter of the shape memory alloy wire that meets the expected diameter is defined as D, and D≤0.7 mm is satisfied.

7. The method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis according to claim 1, characterized in that: The spring pitch of the shape memory alloy spring is defined as h, and h satisfies 0.4 mm ≤ h ≤ 0.6 mm.

8. The method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis according to claim 1, characterized in that: The height of the second elliptical cylindrical nucleus pulposus prosthesis is defined as H, and H satisfies 5mm≤H≤9mm.

9. The method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis according to claim 1, wherein: The minor axis length of the elliptical cylindrical cavity of the second mold is 12 mm, and the major axis length of the elliptical cylindrical cavity of the second mold is 25 mm.

10. The method for manufacturing a shape memory alloy artificial nucleus pulposus prosthesis according to claim 1, characterized in that: The material of the shape memory alloy plate is one of titanium-nickel alloy, titanium-nickel-zirconium alloy, titanium-nickel-hafnium alloy, titanium-nickel-iron alloy, titanium-nickel-copper alloy, titanium-nickel-copper-aluminum alloy, copper-aluminum-manganese alloy, copper-aluminum-nickel alloy, copper-zinc-aluminum alloy, iron-nickel-cobalt-titanium alloy, iron-nickel-cobalt-aluminum alloy or iron-manganese-silicon alloy.

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