Woven-knitted sectional type colorectum nickel-titanium alloy stent and preparation method thereof

Abstract

The invention belongs to the technical field of biomedical textile products, and relates to a woven-knitted sectional type colorectum nickel-titanium alloy stent and a preparation method thereof.The stent comprises a stent main section, and the two ends of the stent main section are sequentially connected with a first bent flexible supporting section, a second bent flexible supporting section and a stent end section respectively; the stent main section, the first bending flexible supporting section, the second bending flexible supporting section and the stent end section are all obtained through a knitting process, and the adjacent sections are connected through the knitting process; during preparation, one metal wire is adopted, one stent end section, one second bending flexible supporting section, one first bending flexible supporting section, one stent main section, the other first bending flexible supporting section, the other second bending flexible supporting section and the other stent end section are woven in sequence, and the stent is obtained through integral forming. During preparation, a sectional knitting-weaving forming technology is adopted, and required bending flexibility is provided; the prepared stent has excellent anti-migration effect and bending flexibility.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of biomedical textile products, and relates to a braiding-knitting segmented colorectal nickel-titanium alloy stent and a preparation method thereof. BACKGROUND

[0002] Colorectal cancer causes the tumor to continuously proliferate in the intestinal wall, resulting in complete or incomplete obstruction of the patient. Such patients need emergency intestinal decompression to avoid abdominal distension, intestinal wall circulation disorders, and the like.

[0003] Implantation of a colorectal stent becomes an auxiliary therapy for the intestinal tract to fully decompress and recover for surgery. Not only can it quickly relieve the patient's colorectal obstruction and alleviate their pain, but it can also bring hope for the patient's physical and mental recovery and even the next step of surgical treatment. Recently, in the preparation of colorectal stents, metals and alloys have been proven to be effective in promoting stent expansion. Currently, the material used in colorectal stents is generally a nickel-titanium memory alloy material, which is usually in a braided structure so that the stent can maintain good radial support when it deforms with the natural bending and peristalsis of the intestinal tract. However, according to existing reports, the existing metal stents have limitations, such as restenosis caused by migration of more than 1 cm from the implanted position. Theoretical studies have shown that the main cause of stent migration is the radial support performance of the stent, followed by the bending flexibility of the stent. Therefore, due to the lack of these two characteristics, clinical investigation and research have reported that the incidence of complications such as migration and perforation after implantation of the stent using the existing technology is as high as 15-20 %, which greatly affects the treatment effectiveness of the patient.

[0004] Many reports indicate that, in order to ensure that the implanted colorectal stent is stable and fixed in the body without migration, the existing technology uses a method of greatly increasing the edge diameter of the stent. However, this method easily causes serious complications such as perforation, which endangers the life safety of the patient. Currently, the textile processes used to prepare intestinal stents mainly include knitting and braiding, both of which have their advantages and limitations. Braided stents have strong self-expanding properties and are easy to expand the intestinal tract, but they are easily deformed under external force, which can lead to migration of the stent. In addition, the diameter of the stent in the bending area may be reduced, which can reduce the stability of the stent and thus weaken the treatment effect. In contrast, knitted stents have good bending flexibility and high radial stiffness, but they have poor self-expanding properties. Therefore, there are limitations in using a single process for preparation.

[0005] Patent US9861506B2 discloses a wire fully braided structure stent for reducing the perforation rate, which does not take into account the segmented radial performance and bending flexibility. Patent WO 2015 / 174730 A1 discloses a stent manufacturing method for expansion, which forms a hollow cylinder by braiding metal wires as a first main body part, forms a second main body part by braiding metal wires and surrounding the hollow cylinder of the first main body part, integrally forms the expansion part of both ends of the first main body part and the second main body part and coats; however, this patent does not explain how to avoid stent displacement.

[0006] The stents of the prior art can indeed achieve bending flexibility and radial support to some extent, but often need to trade off between the two characteristics, and it is difficult to achieve the optimal balance of both performances.

[0007] For example, document 1 (Evaluation of mechanical properties of self-expanding metal stents for optimization of tracheal collapse in dogs[J]. Canadian Journal of Veterinary Research, 2022, 86(3): 188-193.) once evaluated the radial support of 6 different commercially available colorectal stents, and the test results showed that the radial strength of the stents was 0.45 N / mm 2 , the maximum was 1.22 N / mm 2 , and the radial strength of most stents was between 0.7~1.0 N / mm 2 ; the bending stiffness value was 6.6 N·m. In addition, another study published in document 2 (Laasch H U, Milward G D, Edwards D W. ‘Radial force’ of colonic stents: A parameter without consistency, definition or standard[J]. International Journal of Gastrointestinal Intervention, 2020, 9(3): 99-105.) in 2020 also tested 4 different stents, and the report showed that the radial support of these stents was in the range of 0.56~1.15 N / mm2; the bending stiffness value was 6.6 N·m.

[0008] A 2019 study in Digestive Endoscopy examined seven commercially available stents and found that the minimum bending stiffness of the stents was 0.022 N·m and the maximum was 0.081 N·m. In addition, a 2018 study reported in Literature 3 (Super-Flexible Through-the-Scope Self-Expandable Metallic Stent Insertion for the Management of Malignant Tortuous Hepatic or Splenic Flexure Colonic Obstruction [J]. Chinese Medical Journal, 2018, 131(11): 1381-1384.) also mentioned that the bending stiffness values of six different models of commercially available colorectal stents were between 0.027 N·m and 0.112 N·m; the radial strength was between 2.47 and 6.02 N / mm 2 .

[0009] Therefore, it is of great significance to study a braiding-knitting segmented colorectal nickel-titanium alloy stent and its preparation method to solve the problems existing in the prior art. SUMMARY

[0010] The purpose of the present application is to solve the problems existing in the prior art and provide a braiding-knitting segmented colorectal nickel-titanium alloy stent and its preparation method.

[0011] To achieve the above-mentioned purpose, the technical solutions adopted by the present application are as follows:

[0012] A braiding-knitting segmented colorectal nickel-titanium alloy stent, the nickel-titanium alloy stent material is relatively suitable for use in related clinical treatment for unblocking pipeline obstruction due to its self-expanding property and good mechanical strength. The nickel-titanium alloy stent is a tubular structure, which includes a stent main segment, the two ends of the stent main segment are connected in turn with a first curved flexible support segment, a second curved flexible support segment and a stent end segment; when performing minimally invasive treatment stent implantation, the tubular structure is beneficial to firmly attaching the expanded stent to the target site. The stent has good flexibility, radial strength and self-expandability;

[0013] The stent main segment, the first curved flexible support segment, the second curved flexible support segment and the stent end segment are obtained by braiding process, and the adjacent segments are connected by knitting process;

[0014] The stent main section and the stent end section are cylindrical structures, the first curved flexible support section and the second curved flexible support section are circular table structures, the first curved flexible support section and the second curved flexible support section are connected through the small ends to form a V-shaped structure (i.e. the generatrix of the first curved flexible support section and the second curved flexible support section form a certain angle with each other), and the V-shaped structure is formed by the stent main section and each stent end section through mutual nesting of two coils; when the stent is bent, the angle of the V-shaped structure formed by the mutual nesting of the coils can be changed, thereby giving the stent good bending compliance.

[0015] The radial strength of the stent main section is 4-10 N / mm 2 , the radial strength of the stent end section is greater than that of the stent main section, and preferably the radial strength of the stent end section is 1.5 times that of the stent main section; the radial strength of the stent, especially at the flange section (i.e. the stent end section), plays a crucial role in maintaining the position of the stent and resisting the migration of the stent. In clinical applications, increasing the diameter of the stent has the risk of causing the stent to pierce the wall of the intestinal cavity. Therefore, increasing the diameter of the flange section to enhance the anti-migration ability without significantly increasing the diameter of the stent body is a good method (i.e. appropriately increasing the diameter of the flange section without increasing the diameters of the remaining sections), which can maximize the overall radial strength of the stent while reducing the risk of damage to the surrounding tissues. To achieve the radial strength of the stent end section greater than that of the stent main section, one is to control the length of the stent end section to be less than the length of the main section, and the other is to make the weaving of the stent end section more compact than that of the main section, which corresponds to an increase in weaving density, so that the stent can more evenly disperse the load when compressed, reducing the possibility of local deformation, thereby enhancing the resistance of the stent to the compression load.

[0016] Preferably, the nickel-titanium alloy wires on the stent main section are woven at equal intervals, and the helix angle is 60°; the helix angle of the nickel-titanium alloy wires on the two curved flexible support sections is 45°, so as to increase the friction with the colon wall and improve the radial support force.

[0017] As a preferred technical solution:

[0018] The length of the stent end section is 10-20 mm, which is determined according to the required fixed size of the intestinal site, and the longer the flange part, the better the fixing effect; the length of the stent main section is 30-40 mm, i.e. the length of the tumor or the stenosis part, and intestinal stenosis is one of the common complications of inflammatory bowel disease, and the stenosis part refers to the site where the intestinal stenosis occurs.

[0019] The opening angle of the V-shaped structure formed by the connection of the first curved flexible support section and the second curved flexible support section is 50°-130°.

[0020] The braiding-knitting segmented colorectal nickel-titanium alloy stent has a braiding density of 3-5 / cm for the stent end section, and the braiding density of the stent end section is 1-1.5 times that of the main section of the stent.

[0021] The braiding-knitting segmented colorectal nickel-titanium alloy stent has a braiding-knitting segmented colorectal nickel-titanium alloy stent.

[0022] The braiding-knitting segmented colorectal nickel-titanium alloy stent has a braiding-knitting segmented colorectal nickel-titanium alloy stent.

[0023] The braiding-knitting segmented colorectal nickel-titanium alloy stent has a braiding-knitting segmented colorectal nickel-titanium alloy stent.

[0024] As a preferred technical solution:

[0025] The braiding-knitting segmented colorectal nickel-titanium alloy stent has a braiding-knitting segmented colorectal nickel-titanium alloy stent.

[0026] (1) Preparation of the mold;

[0027] The mold is formed by connecting a cylinder I, a circular table I, a circular table II, a cylinder II, a circular table III, a circular table IV and a cylinder III in sequence; wherein the diameter of the cylinder I, the large end diameter of the circular table I, the large end diameter of the circular table II, the diameter of the cylinder II, the large end diameter of the circular table III, the large end diameter of the circular table IV and the diameter of the cylinder III are equal, the small end diameter of the circular table I, the small end diameter of the circular table II, the small end diameter of the circular table III and the small end diameter of the circular table IV are equal; one end of the cylinder I is fixedly connected with the large end of the circular table I, the small end of the circular table I is fixedly connected with the small end of the circular table II, and the large end of the circular table II is fixedly connected with one end of the cylinder II; the other end of the cylinder II is fixedly connected with the large end of the circular table III, the small end of the circular table III is fixedly connected with the small end of the circular table IV, and the large end of the circular table IV is fixedly connected with one end of the cylinder III;

[0028] Along the axial direction of the mold, the peripheral surface of the mold is provided with i thread hole groups, each thread hole group including j thread holes, and the j thread holes are uniformly distributed along the circumferential direction of the mold; wherein, the cylinder I is provided with a thread hole group, the cylinder II is provided with b thread hole groups, the cylinder III is provided with c thread hole groups, the connecting part of the circular table I and the circular table II is provided with 1 thread group, and the connecting part of the circular table III and the circular table IV is provided with 1 thread group; among the a thread hole groups provided on the cylinder I, one thread hole group is located at the connecting part of the cylinder I and the circular table I; among the b thread hole groups provided on the cylinder II, one thread hole group is located at the connecting part of the cylinder II and the circular table II, and one thread hole group is located at the connecting part of the cylinder II and the circular table III; a+b+c+2=i, j≥9;

[0029] All the thread holes on the mold are respectively and individually screw-connected with a screw, and the thread holes on the mold are arrayed distributed;

[0030] (2) Preparation of the support end section corresponding to the cylinder I;

[0031] Record a thread hole on a thread hole group as the first thread hole, and the last thread hole in the clockwise direction from the first thread hole is the jth thread hole; record the thread hole group farthest from the cylinder III on the cylinder I as the first thread hole group, and the last thread hole group in the direction from the cylinder I to the cylinder III from the first thread hole group is the ith thread hole group; wherein, the screw corresponding to the yth thread hole of the xth thread hole group is marked as screw-x-y, 1≤x≤i, 1≤y≤j;

[0032] Fix one end of a metal wire on the screw-a-1, and the other end of the metal wire is wound back and forth around one screw corresponding to the first thread hole group and one screw corresponding to the a th thread hole group; both the screw corresponding to the first thread hole group and the screw corresponding to the a th thread hole group are wound by the metal wire once;

[0033] Wherein, the winding rule of the end of the metal wire after being fixed on the screw-a-1 is: when y takes any value, the metal wire first winds around the screw-1-y, then winds around the screw-a-f(y+d+1), and then winds around the screw-1-f(y+e+1); d is the number of screws between the two adjacent screws on the first thread hole group and the a th thread hole group that are first wound by the metal wire along the circumferential direction; e is the number of screws between the two adjacent screws on the first thread hole group or the a th thread hole group that are first wound by the metal wire;

[0034] The expression of the function f(k) is:

[0035] f(k)=(k-j)×θ(k-j)+k×[1-θ(k-j)];

[0036] θ(G) is a step function, when G>0, θ(G) is 1, when G≤0, θ(G) is 0;

[0037] Wherein, j is an odd number, e≥3, j≥2e+2, d

[0038] When the metal wire is wound on the screw-a-1 (the end of the metal wire is fixed on the screw-a-1 and is not counted as winding), the support end section corresponding to the cylinder I is prepared;

[0039] (3) Preparation of the second curved flexible support section corresponding to the circular table I;

[0040] After the metal wire is wound on the screw-a-1 in step (2), the metal wire is wound on a screw corresponding to the a+1th threaded hole group and a screw corresponding to the ath threaded hole group back and forth; the screw corresponding to the a+1th threaded hole group and the screw corresponding to the ath threaded hole group are both wound by the metal wire once;

[0041] Wherein, the winding rule of the metal wire after being wound on the screw-a-1 is: when y takes any value, the metal wire is first wound on the screw-(a+1)-y, then wound on the screw-a-f(y+1), and then wound on the screw-(a+1)-f(y+2);

[0042] When the metal wire passes through a screw corresponding to the ath threaded hole group each time, the metal wire passes through the coil formed by the support end section corresponding to the cylinder I at the screw;

[0043] After the screw corresponding to the a+1th threaded hole group and the screw corresponding to the ath threaded hole group are both wound by the metal wire once, when the metal wire is wound on the screw-a-1 again, the second curved flexible support section corresponding to the circular table I is prepared;

[0044] (4) Preparation of the first curved flexible support section corresponding to the circular table II;

[0045] After the metal wire is wound on the screw-a-1 in step (3), the metal wire is first wound on the screw-(a+2)-2, and then wound on a screw corresponding to the a+1th threaded hole group and a screw corresponding to the a+2th threaded hole group back and forth; the screw corresponding to the a+1th threaded hole group and the screw corresponding to the a+2th threaded hole group are both wound by the metal wire once;

[0046] Wherein, the winding rule of the metal wire after being wound on the screw-(a+2)-2 is: when y takes any value, the metal wire is first wound on the screw-(a+1)-y, then wound on the screw-(a+2)-f(y+1), and then wound on the screw-(a+1)-f(y+2);

[0047] Each time the metal wire passes through a screw corresponding to the (a+1)th thread hole group, the metal wire passes through the coil formed by the second curved flexible support section corresponding to the circular platform I at the screw;

[0048] When the screw corresponding to the (a+1)th thread hole group and the screw corresponding to the (a+2)th thread hole group are both wound by the metal wire once, and the metal wire is wound again on the screw-(a+1)-1, the first curved flexible support section corresponding to the circular platform II is prepared;

[0049] (5) Preparation of the support main section corresponding to the circular column II;

[0050] After the metal wire of step (4) is wound around the screw-(a+1)-1, it is first wound around the screw-(a+b+1)-5, and then wound around the screw-(a+2)-9, and then wound back and forth around a screw corresponding to the (a+2)th thread hole group and a screw corresponding to the (a+b+1)th thread hole group; the screw corresponding to the (a+2)th thread hole group and the screw corresponding to the (a+b+1)th thread hole group are both wound by the metal wire once;

[0051] Wherein, the winding rule after the metal wire is wound around the screw-(a+2)-9 is: when y takes any value, the metal wire is first wound around the screw-(a+2)-y, and then wound around the screw-(a+b+1)-f(y+m), and then wound around the screw-(a+2)-f(y+2m);

[0052] Wherein, m-1 is the number of screws between two adjacent screws wound by the metal wire in sequence on the (a+2)th thread hole group and the (a+b+1)th thread hole group; 2m-1 is the number of screws between two adjacent screws wound by the metal wire in sequence on the (a+2)th thread hole group or the (a+b+1)th thread hole group; 2m-1≥7;

[0053] Each time the metal wire passes through a screw corresponding to the (a+2)th thread hole group, the metal wire passes through the coil formed by the first curved flexible support section corresponding to the circular platform II at the screw;

[0054] When the screw corresponding to the (a+2)th thread hole group and the screw corresponding to the (a+b+1)th thread hole group are both wound by the metal wire once, and the metal wire is wound again on the screw-(a+2)-1, the support main section corresponding to the circular column II is prepared;

[0055] (6) Preparation of the first curved flexible support section corresponding to the circular platform III;

[0056] After the wire of step (5) is wound around screw-(a+b+1)-3, the wire is wound around screw-(a+b+2)-2 first, then around screw-(a+b+1)-3, and then back and forth around one screw corresponding to the a+b+2th threaded hole group and one screw corresponding to the a+b+1th threaded hole group; both the screw corresponding to the a+b+2th threaded hole group and the screw corresponding to the a+b+1th threaded hole group are wound by the wire once;

[0057] wherein, after the wire is wound around screw-(a+b+1)-3, the winding rule is that when y takes any value, the wire is wound around screw-(a+b+1)-y first, then around screw-(a+b+2)-f(y+1), and then around screw-(a+b+1)-f(y+2);

[0058] each time the wire passes through one screw corresponding to the a+b+2th threaded hole group, the wire passes through the loop formed by the main section of the support corresponding to the cylindrical II at the screw;

[0059] After both the screw corresponding to the a+b+1th threaded hole group and the screw corresponding to the a+b+2th threaded hole group are wound by the wire once, when the wire is wound around screw-(a+b+1)-1 again, the first curved flexible support section corresponding to the circular truncated cone III is prepared;

[0060] (7) Preparation of the second curved flexible support section corresponding to the circular truncated cone IV;

[0061] After the wire of step (6) is wound around screw-(a+b+1)-1, the wire is wound around screw-(a+b+3)-3 first, then around screw-(a+b+2)-4, and then back and forth around one screw corresponding to the a+b+3th threaded hole group and one screw corresponding to the a+b+2th threaded hole group; both the screw corresponding to the a+b+3th threaded hole group and the screw corresponding to the a+b+2th threaded hole group are wound by the wire once;

[0062] wherein, after the wire is wound around screw-(a+b+2)-4, the winding rule is that when y takes any value, the wire is wound around screw-(a+b+2)-y first, then around screw-(a+b+3)-f(y+1), and then around screw-(a+b+2)-f(y+2);

[0063] each time the wire passes through one screw corresponding to the a+b+2th threaded hole group, the wire passes through the loop formed by the first curved flexible support section corresponding to the circular truncated cone III at the screw;

[0064] When the screw corresponding to the a+b+3th thread hole group and the screw corresponding to the a+b+2th thread hole group are both wound by the wire once, the wire is wound onto the screw-(a+b+3)-1, and the second curved flexible support section corresponding to the circular truncated cone IV is prepared;

[0065] (8) Preparation of the bracket end section corresponding to the circular cylinder III;

[0066] After the wire of step (7) is wound around the screw-(a+b+3)-1, it is first wound around the screw-(a+b+c+2)-3, then wound around the screw-(a+b+3)-5, and then wound back and forth around one screw corresponding to the a+b+c+2th thread hole group and one screw corresponding to the a+b+3th thread hole group; the screw corresponding to the a+b+c+2th thread hole group and the screw corresponding to the a+b+3th thread hole group are both wound by the wire once;

[0067] wherein, after the wire is wound around the screw-(a+b+3)-5, the winding rule is that when y takes any value, the wire is first wound around the screw-(a+b+3)-y, then wound around the screw-(a+b+c+2)-f(y+q), and then wound around the screw-(a+b+3)f(y+2q);

[0068] wherein, q-1 is the number of screws between two adjacent screws corresponding to the a+b+c+2th thread hole group and the a+b+3th thread hole group that are wound by the wire in sequence, and 2q-1 is the number of screws between two adjacent screws corresponding to the a+b+c+2th thread hole group or the a+b+3th thread hole group that are wound by the wire in sequence, and 2q-1≥3;

[0069] When the wire passes through one screw corresponding to the a+b+3th thread hole group each time, the wire passes through the loop formed at the screw by the second curved flexible support section corresponding to the circular truncated cone IV;

[0070] When the screw corresponding to the a+b+c+2th thread hole group and the screw corresponding to the a+b+3th thread hole group are both wound by the wire once, the wire is wound onto the screw-(a+b+3)-1 again, and the bracket end section corresponding to the circular cylinder III is prepared;

[0071] (9) The end of the wire is fixed on the bracket end section corresponding to the circular cylinder III, and the structure preparation of the braiding-knitting segmented colonic nickel-titanium alloy stent is completed;

[0072] (10) After the product of step (9) and the mold are washed, dried and heat set together, the mold is removed, and one end of the wire fixed on the screw-a-1 in step (2) is fixed on the bracket end section corresponding to the circular cylinder I, thereby preparing the braiding-knitting segmented colonic nickel-titanium alloy stent.

[0073] It should be noted that in the braiding process of the first curved flexible support section and the second curved flexible support section of the stent, that is, the connection between cylinder I and circular truncated cone I, the connection between circular truncated cone I and circular truncated cone II, the connection between circular truncated cone II and cylinder II, the connection between cylinder II and circular truncated cone III, the connection between circular truncated cone III and circular truncated cone IV, and the connection between circular truncated cone IV and cylinder III, the metal wire is not simply wound around the screw, but needs to be wound through the metal wire previously wound around the corresponding screw, so as to realize the coil structure of the first curved flexible support section and the second curved flexible support section.

[0074] The preparation method of the braiding-knitting segmented colorectal nickel-titanium alloy stent as described above, the temperature of the heat treatment is 475-500 DEG C, and the time is 20-25 min.

[0075] The preparation method of the braiding-knitting segmented colorectal nickel-titanium alloy stent as described above, 3 ≤ a ≤ 5, 5 ≤ b ≤ 12, 3 ≤ c ≤ 5, 12 ≤ j ≤ 32, 3 ≤ d ≤ 5, 1 ≤ e ≤ 3, 7 ≤ 2m-1 ≤ 21, 3 ≤ 2q-1 ≤ 5.

[0076] The preparation method of the braiding-knitting segmented colorectal nickel-titanium alloy stent as described above, in the mold, the diameter of cylinder I is 22-30 mm, and the small end diameter of circular truncated cone I is 16-20 mm.

[0077] Invention principle:

[0078] The braiding-knitting segmented colorectal nickel-titanium alloy stent provided by the application has the following advantages: the "V" shaped structure can increase the bending flexibility of the two ends and the middle main body of the stent through the mutual hooking of the coils, and when the stent expands to form a stable structure at the narrow part of the intestine, the sliding locking effect of the coils can prevent the stent from migrating. Specifically, the "V" shaped structure of the stent allows the stent to smoothly slide and approach each other at the part where the coils are hooked to each other, thereby realizing better bending flexibility of the stent. In addition, the "V" shaped structure provides a second advantage: it helps to lock the stent in place and resist the migration of the stent caused by the peristalsis of the intestinal lumen. The bending and sliding of the stent can be realized by adjusting the angle of the coil hooking part. In general, compared with direct braiding connection or mutual connection of single coils, the "V" shaped structure can more effectively improve the bending compliance and anti-migration performance of the stent through the sliding and locking of the coil part.

[0079] The arrangement and configuration of different segments adopted by the present application make the segments of the stent have different radial compression properties, which can reduce the discomfort of the patient caused by the excessive expansion of the stent at the stenosis. Specifically, the compression property of each segment can be enhanced by increasing the number of braided wires or shortening the length of the segment. The number of braided wires is proportional to the radial strength, and the length of the segment is inversely proportional to the radial property. Compared with other ordinary intestinal stents which uniformly expand the stenosis part by self-expansion, the radial self-expansion size of each segment part is controllable, which can be adjusted according to the stenosis condition of the patient's intestine, and the discomfort of the patient during the self-expansion of the stent is minimized. In addition, the good self-expansion performance of the flange segment of the segmented design can effectively prevent the stent from being offset due to the compression of the flange.

[0080] The segmented structure design adopted by the present application, through its specific geometric and structural characteristics, makes the stent realize the combination of excellent flexibility and radial support property. In addition, in terms of material selection, the selected nickel-titanium alloy wire has excellent mechanical properties and shape memory effect, which can ensure that the stent realizes the required flexibility and radial support.

[0081] (1) Radial support property:

[0082] ① The radial support property of the braided segment is determined by the comprehensive resistance encountered when the alloy wires slide relative to each other. By controlling the friction force (Fr) and the number of overlaps (n) between the alloy wires, the radial compression force of the stent can be adjusted, which is specifically represented as:

[0083] ;

[0084] ② The radial support property of the knitted segment depends not only on the sliding friction of the overlapping alloy wires, but also on the bending of the knitted loops to pull the wires closer and reduce the radius. During the process of compressing the stent to achieve the minimum radius, the bending strength of the metal wires will add extra force to the stent to achieve greater radial strength. Specifically represented as:

[0085] + ;

[0086] The radial support property of the entire segmented stent is provided by the above two parts, as shown in Figure 15 .

[0087] Compared with the prior art, the present application has the following differences:

[0088] (1) Integrating two structures (knitting and braiding) into a single stent (i.e. Figure 6 and Figure 7 , Figure 5 where h, j, k and m are the connection points of the two structures);

[0089] (2) Each segment exists independently to form a stent: the stent is designed in segments, and different segments are designed to achieve specific functions.

[0090] (3) Connection of each segment: each segment is prepared by knitting, and the specific connection between segments is knitting technology, which is crucial to the overall function and stability of the stent.

[0091] (4) Design at the junction of each segment: the minimum diameter of the junction is considered in the design to facilitate the stent to maintain structural stability in the maximum bending activity. This is due to the range of motion allowed by the loops at junctions h, j, k, and m. Figure 5

[0092] The segmented design of the stent allows each segment to move and deform independently to some extent without significantly affecting adjacent segments. Adjacent segments only have an impact when the deformation of adjacent segments is large enough to exert pressure, thereby enhancing the anti-migration performance of the stent.

[0093] The loop gap in the connection between segments of the stent design allows the loops to slide and bend. In addition, the stent is knitted from a continuous alloy wire. This continuous alloy wire knitting design, combined with the loop sliding gap, facilitates the independent movement of each segment of the stent, significantly enhancing the overall anti-migration performance of the stent. The sliding gap of the loop is the size of the loop formed during knitting, i.e., the formation of a knitted loop can form a sliding gap; existing knitted stents can achieve anti-migration function, but their anti-migration only exists in the radial direction. The "V-shaped" structure obtained by the "knitting + knitting" method used in this invention has better bending flexibility and adaptability to the intestinal structure, and its anti-migration performance is better.

[0094] As shown in Figure 19 , the load conversion of the force applied at a has little effect on the last segment g, which is due to the slow transmission of force by alloy wire and loop deformation, which cannot be achieved in continuous knitting or knitted stents.

[0095] The segmented stent design presented in this invention aims to integrate segments with different radial support performance and diameter sizes into one body, with each segment designed with independent and specialized bending flexibility and radial support.

[0096] ​An ideal colorectal stent has good anti-migration, self-expanding, high bending flexibility, high radial stiffness and other properties, which can support and expand the intestine, and adapt to the natural bending of the intestine, thereby effectively relieving colorectal obstruction. According to the segmented colorectal nickel-titanium alloy stent provided by the application, the tubular fabric is knitted and connected after being knitted by segmenting a nickel-titanium alloy wire. The stent can be placed in the intestinal stenosis section from the endoscope through a guide wire and released, thereby generating a continuous expansion force to support the intestinal stenosis section, so that the stenosis section recovers. It also has good radial support performance and flexibility, which makes up for the design defects of existing commercial colorectal stents, thereby quickly relieving the obstruction symptoms and reducing the risk of migration and perforation.

[0097] Advantages:

[0098] (1) The preparation method of the knitted-segmented colorectal nickel-titanium alloy stent of the application connects the edges (flanges) of the two ends of the stent and the main body segment of the stent in the form of interlocking knitted loops, forms a "V-shaped" structure, and gives the stent a certain bending flexibility. By controlling the knitting angle (spiral angle) of the main body part and the "V-shaped" structure of the stent, the radial support of the stent can be controlled as needed.

[0099] (2) The preparation method of the knitted-segmented colorectal nickel-titanium alloy stent of the application uses segmented knitting- weaving forming technology, which avoids the problem that the flexibility and radial support of a single stent preparation process cannot be satisfied at the same time. Without sacrificing the radial support of the stent, the required bending flexibility is provided, allowing the stent to bend naturally in the colorectum, and ensuring the normal function of the stent.

[0100] (3) The knitted-segmented colorectal nickel-titanium alloy stent of the application has a larger diameter at the two end flanges, which plays a role in resisting migration of the stent. At the same time, the design of increasing the radial strength and bending flexibility of the stent can make the stent fit the intestine better, and also reduce the risk of migration and perforation.

[0101] (4) The knitted-segmented colorectal nickel-titanium alloy stent prepared by the application improves its radial strength without significantly increasing the diameter of the stent.

[0102] (5) The knitted-segmented colorectal nickel-titanium alloy stent prepared by the application has good anti-migration performance, which effectively reduces the incidence of complications after intestinal stent implantation. BRIEF DESCRIPTION OF DRAWINGS

[0103] Figure 1 It is a perspective view of the segmented component of the knitted-segmented colorectal nickel-titanium alloy stent.

[0104] Figure 2 Perspective view of a braided-knitted segmented colorectal nitinol stent; where p is the braided intersection of the main stent segment, j is the connection point of the first curved flexible support segment of the upper end and the main stent segment.

[0105] Figure 3 Cross-sectional view of a braided-knitted segmented colorectal stent.

[0106] Figure 4 Cross-sectional view of a braided-knitted segmented colorectal stent in an enteroscope guide tube.

[0107] Figure 5 Schematic diagram of the connection points of each segment of the stent; where h is the connection point of the upper end segment of the stent and the second curved flexible support segment of the upper end, i is the connection point of the first curved flexible support segment of the upper end and the second curved flexible support segment of the upper end, j is the connection point of the first curved flexible support segment of the upper end and the main stent segment, k is the connection point of the main stent segment and the first curved flexible support segment of the lower end, l is the connection point of the second curved flexible support segment of the lower end and the first curved flexible support segment of the lower end, m is the connection point of the second curved flexible support segment of the lower end and the lower end segment of the stent, o is the connection point of the first curved flexible support segment of the lower end and the second curved flexible support segment of the lower end, and p is the braided intersection of the main stent segment.

[0108] Figure 6 Schematic diagram of the braided portion structure of the stent; where A is the braided segment.

[0109] Figure 7 Schematic diagram of the knitted portion structure of the stent; where B is the knitted segment.

[0110] Figure 8 “V-shaped” structure of the connection point.

[0111] Figure 9 Connection between different segments.

[0112] Figure 10 Braiding method diagram of the curved flexible support segment of the stent; red lines represent a knitted loop, and yellow lines represent the knitted direction of the metal wire in the curved flexible support segment of the stent.

[0113] Figure 11 Overall organization braiding diagram of the stent.

[0114] Figure 12 Braiding mold diagram.

[0115] Figure 13 Schematic diagram of the connection of each segment of the stent.

[0116] Figure 14 Front view of the mold.

[0117] Figure 15 For radial support performance analysis of each part of the stent; wherein A is the braided section, and B is the knitted section.

[0118] Figure 16 For the load applied before deformation of adjacent sections and the freedom of the coil when sliding.

[0119] Figure 17 For the coil configuration of the knitted part of the stent in different states.

[0120] Figure 18 For the bending flexibility comparison chart of the stent of the present application and the existing ordinary stent; wherein, Figure 18 (a) is a detail view of the bending flexible support section of the stent of the present application, Figure 18 (b) is a detail view of the bending degree of the metal monofilament of the bending flexible support section of the stent of the present application, Figure 18 (c) is a detail view of the bending degree of the metal monofilament of the bending flexible support section of the existing ordinary stent.

[0121] Figure 19 For the anti-migration performance principle of the stent.

[0122] Wherein, 1 is the end section of the stent, 2 is the second bending flexible support section, 3 is the first bending flexible support section, 4 is the main section of the stent, 5 is the mutually nested coil structure, 6 is the smallest diameter of the stent, 7 is the joint bending connection part, 8 is the largest diameter of the end section of the stent, 14 is the stent delivery system, and 15 is the braided-knitted segmented colorectal nickel-titanium alloy stent. DETAILED DESCRIPTION

[0123] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. In addition, it should be understood that after reading the content taught by the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope of the claims attached to the present application.

[0124] The performance indicators in the examples and comparative examples of the present application involve the following test methods:

[0125] Radial strength: the standard test method is derived from ASTM F3067-14(2021), which is used to evaluate the radial load bearing capacity of cylindrical vascular stents under pressure. This test must be carried out in an in vitro environment, is only applicable to regular cylindrical stent structures, and the measurement unit is the international standard unit (SI).

[0126] Resistance to migration: The standard test method is derived from ASTM F3067-14 (2021) and indirectly assesses the ability of the stent to resist radial deformation and axial displacement in vivo through a radial strength test. The method relies on the hysteresis and permanent set of the radial load-deformation curve to judge the resistance to migration performance. The test must be performed in vitro, at standard temperature, using SI units.

[0127] Flexural compliance: The standard test method is derived from ASTM F2606-08 (2021) and measures the flexibility and stiffness of the stent system during bending using a three-point bending test method. The test requires a test span to outer diameter ratio of no less than 4:1 to ensure that the dominant deformation is bending rather than compression or shear. The test must be performed in SI units, and force-displacement or moment-curvature data are recorded for evaluation of the compliance.

[0128] A preparation method of a braided-knitted segmented colorectal nickel-titanium alloy stent, the specific steps are as follows:

[0129] (1) Preparation of the mold;

[0130] As shown in Figure 12 , Figure 14 , the mold is formed by connecting a cylinder I, a circular truncated cone I, a circular truncated cone II, a cylinder II, a circular truncated cone III, a circular truncated cone IV and a cylinder III in sequence; wherein the diameter of the cylinder I, the large end diameter of the circular truncated cone I, the large end diameter of the circular truncated cone II, the diameter of the cylinder II, the large end diameter of the circular truncated cone III, the large end diameter of the circular truncated cone IV and the diameter of the cylinder III are equal, and the small end diameter of the circular truncated cone I, the small end diameter of the circular truncated cone II, the small end diameter of the circular truncated cone III and the small end diameter of the circular truncated cone IV are equal; one end of the cylinder I is fixedly connected with the large end of the circular truncated cone I, the small end of the circular truncated cone I is fixedly connected with the small end of the circular truncated cone II, and the large end of the circular truncated cone II is fixedly connected with one end of the cylinder II; the other end of the cylinder II is fixedly connected with the large end of the circular truncated cone III, the small end of the circular truncated cone III is fixedly connected with the small end of the circular truncated cone IV, and the large end of the circular truncated cone IV is fixedly connected with one end of the cylinder III; in the mold, the diameter of the cylinder I is 22-30 mm, and the small end diameter of the circular truncated cone I is 16-20 mm;

[0131] Along the axial direction of the mold, the peripheral surface of the mold is provided with i thread hole groups, each thread hole group including j thread holes, and the j thread holes are uniformly distributed along the circumferential direction of the mold; wherein, the cylinder I is provided with a thread hole group, the cylinder II is provided with b thread hole groups, the cylinder III is provided with c thread hole groups, the connecting part of the circular table I and the circular table II is provided with 1 thread group, and the connecting part of the circular table III and the circular table IV is provided with 1 thread group; among the a thread hole groups provided on the cylinder I, one thread hole group is located at the connecting part of the cylinder I and the circular table I; among the b thread hole groups provided on the cylinder II, one thread hole group is located at the connecting part of the cylinder II and the circular table II, and one thread hole group is located at the connecting part of the cylinder II and the circular table III; a+b+c+2=i; wherein, 3 ≤ a ≤ 5, 5 ≤ b ≤ 12, 3 ≤ c ≤ 5, and 12 ≤ j ≤ 32;

[0132] All the thread holes on the mold are respectively and individually screw-connected with a screw, and the thread holes on the mold are arrayed distributed;

[0133] (2) Preparation of the support end section corresponding to the cylinder I;

[0134] A thread hole on a thread hole group is recorded as the first thread hole, and the last thread hole in the clockwise direction from the first thread hole is recorded as the jth thread hole; the thread hole group farthest from the cylinder III on the cylinder I is recorded as the first thread hole group, and the last thread hole group in the direction from the cylinder I to the cylinder III from the first thread hole group is recorded as the ith thread hole group; wherein, the screw corresponding to the yth thread hole of the xth thread hole group is marked as screw-x-y, 1 ≤ x ≤ i, and 1 ≤ y ≤ j;

[0135] One end of a metal wire is fixed on the screw-a-1, and the other end is wound back and forth around one screw corresponding to the first thread hole group and one screw corresponding to the a th thread hole group; both the screw corresponding to the first thread hole group and the screw corresponding to the a th thread hole group are wound by the metal wire once; the metal wire is a nickel-titanium alloy wire with a diameter of 0.28 mm;

[0136] Wherein, the winding rule of the metal wire after being fixed on the screw-a-1 is that: when y takes any value, the metal wire first winds around the screw-1-y, then winds around the screw-a-f(y+d+1), and then winds around the screw-1-f(y+e+1); d is the number of interval screws between the two adjacent screws on the first thread hole group and the a th thread hole group that are wound by the metal wire in sequence along the circumferential direction; e is the number of interval screws between the two adjacent screws on the first thread hole group or the a th thread hole group that are wound by the metal wire in sequence; wherein, 3 ≤ d ≤ 5, and 1 ≤ e ≤ 3;

[0137] The expression of the function f(k) is:

[0138] f(k) = (k - j) x Θ(k - j) + k x [1 - Θ(k - j)];

[0139] Θ(G) is a step function, Θ(G) is 1 when G > 0, and Θ(G) is 0 when G≤0;

[0140] Wherein, j is an odd number, e≥3, j≥2e+2, d<e;

[0141] When the metal wire is wound on the screw-a-1 (the end of the metal wire is fixed on the screw-a-1 and is not counted as winding), the corresponding support end segment of the cylinder I is obtained;

[0142] (3) Preparation of the second curved flexible support segment corresponding to the circular table I;

[0143] After the metal wire is wound around the screw-a-1 in step (2), it is wound back and forth around one screw corresponding to the a+1th threaded hole group and one screw corresponding to the ath threaded hole group; both the screw corresponding to the a+1th threaded hole group and the screw corresponding to the ath threaded hole group are wound once by the metal wire;

[0144] Wherein, the winding rule of the metal wire after being wound on the screw-a-1 is: when y takes any value, the metal wire is first wound around the screw-(a+1)-y, then around the screw-a-f(y+1), and then around the screw-(a+1)-f(y+2);

[0145] When the metal wire passes through one screw corresponding to the ath threaded hole group each time, the metal wire passes through the coil formed at the screw by the support end segment corresponding to the cylinder I;

[0146] After both the screw corresponding to the a+1th threaded hole group and the screw corresponding to the ath threaded hole group are wound once by the metal wire, when the metal wire is wound on the screw-a-1 again, the second curved flexible support segment corresponding to the circular table I is obtained;

[0147] (4) Preparation of the first curved flexible support segment corresponding to the circular table II;

[0148] After the metal wire in step (3) is wound around the screw-a-1, it is first wound on the screw-(a+2)-2, and then wound back and forth around one screw corresponding to the a+1th threaded hole group and one screw corresponding to the a+2th threaded hole group; both the screw corresponding to the a+1th threaded hole group and the screw corresponding to the a+2th threaded hole group are wound once by the metal wire;

[0149] Wherein, the winding rule of the metal wire after being wound on the screw-(a+2)-2 is: when y takes any value, the metal wire is first wound around the screw-(a+1)-y, then around the screw-(a+2)-f(y+1), and then around the screw-(a+1)-f(y+2);

[0150] each time the wire passes through a screw corresponding to the (a+1)th thread hole group, the wire passes through a loop formed by the second curved flexible support section corresponding to the circular truncated cone I at the screw;

[0151] when the screw corresponding to the (a+1)th thread hole group and the screw corresponding to the (a+2)th thread hole group are both wound by the wire once, and the wire is wound onto the screw-(a+1)-1 again, a first curved flexible support section corresponding to the circular truncated cone II is prepared;

[0152] (5) preparation of a support main section corresponding to the circular cylinder II;

[0153] after the wire in step (4) is wound around the screw-(a+1)-1, the wire is first wound around the screw-(a+b+1)-5, then wound around the screw-(a+2)-9, and then wound back and forth around a screw corresponding to the (a+2)th thread hole group and a screw corresponding to the (a+b+1)th thread hole group; the screw corresponding to the (a+2)th thread hole group and the screw corresponding to the (a+b+1)th thread hole group are both wound by the wire once;

[0154] wherein, after the wire is wound around the screw-(a+2)-9, the winding rule is that when y takes any value, the wire is first wound around the screw-(a+2)-y, then wound around the screw-(a+b+1)-f(y+m), and then wound around the screw-(a+2)-f(y+2m);

[0155] wherein, m-1 is the number of screws between two adjacent screws that are wound by the wire in sequence on the (a+2)th thread hole group and the (a+b+1)th thread hole group; 2m-1 is the number of screws between two adjacent screws that are wound by the wire in sequence on the (a+2)th thread hole group or the (a+b+1)th thread hole group; 7≤2m-1≤21;

[0156] each time the wire passes through a screw corresponding to the (a+2)th thread hole group, the wire passes through a loop formed by the first curved flexible support section corresponding to the circular truncated cone II at the screw;

[0157] when the screw corresponding to the (a+2)th thread hole group and the screw corresponding to the (a+b+1)th thread hole group are both wound by the wire once, and the wire is wound onto the screw-(a+2)-1 again, a support main section corresponding to the circular cylinder II is prepared;

[0158] (6) preparation of a first curved flexible support section corresponding to the circular truncated cone III;

[0159] After the wire of step (5) is wound around screw-(a+b+1)-3, the wire is wound around screw-(a+b+2)-2 first, then around screw-(a+b+1)-3, and then back and forth around one screw corresponding to the a+b+2th threaded hole group and one screw corresponding to the a+b+1th threaded hole group; both the screw corresponding to the a+b+2th threaded hole group and the screw corresponding to the a+b+1th threaded hole group are wound by the wire once;

[0160] wherein, after the wire is wound around screw-(a+b+1)-3, the winding rule is that when y takes any value, the wire is wound around screw-(a+b+1)-y first, then around screw-(a+b+2)-f(y+1), and then around screw-(a+b+1)-f(y+2);

[0161] each time the wire passes through one screw corresponding to the a+b+2th threaded hole group, the wire passes through the loop formed by the main section of the support corresponding to the cylindrical II at the screw;

[0162] After both the screw corresponding to the a+b+1th threaded hole group and the screw corresponding to the a+b+2th threaded hole group are wound by the wire once, when the wire is wound around screw-(a+b+1)-1 again, the first curved flexible support section corresponding to the circular truncated cone III is prepared;

[0163] (7) Preparation of the second curved flexible support section corresponding to the circular truncated cone IV;

[0164] After the wire of step (6) is wound around screw-(a+b+1)-1, the wire is wound around screw-(a+b+3)-3 first, then around screw-(a+b+2)-4, and then back and forth around one screw corresponding to the a+b+3th threaded hole group and one screw corresponding to the a+b+2th threaded hole group; both the screw corresponding to the a+b+3th threaded hole group and the screw corresponding to the a+b+2th threaded hole group are wound by the wire once;

[0165] wherein, after the wire is wound around screw-(a+b+2)-4, the winding rule is that when y takes any value, the wire is wound around screw-(a+b+2)-y first, then around screw-(a+b+3)-f(y+1), and then around screw-(a+b+2)-f(y+2);

[0166] each time the wire passes through one screw corresponding to the a+b+2th threaded hole group, the wire passes through the loop formed by the first curved flexible support section corresponding to the circular truncated cone III at the screw;

[0167] When the screw corresponding to the a+b+3th thread hole group and the screw corresponding to the a+b+2th thread hole group are both wound by the wire once, the wire is wound on the screw-(a+b+3)-1, and the second curved flexible support section corresponding to the circular truncated cone IV is prepared;

[0168] (8) Preparation of the stent end section corresponding to the circular cylinder III;

[0169] After the wire of step (7) is wound around the screw-(a+b+3)-1, it is first wound around the screw-(a+b+c+2)-3, then wound around the screw-(a+b+3)-5, and then wound back and forth around one screw corresponding to the a+b+c+2th thread hole group and one screw corresponding to the a+b+3th thread hole group; the screw corresponding to the a+b+c+2th thread hole group and the screw corresponding to the a+b+3th thread hole group are both wound by the wire once;

[0170] wherein, after the wire is wound on the screw-(a+b+3)-5, the winding rule is that when y takes any value, the wire is first wound around the screw-(a+b+3)-y, then wound around the screw-(a+b+c+2)-f(y+q), and then wound around the screw-(a+b+3)f(y+2q);

[0171] wherein, q-1 is the number of screws between two adjacent screws corresponding to the a+b+c+2th thread hole group and the a+b+3th thread hole group that are wound by the wire in sequence, and 2q-1 is the number of screws between two adjacent screws corresponding to the a+b+c+2th thread hole group or the a+b+3th thread hole group that are wound by the wire in sequence; 3≤2q-1≤5;

[0172] When the wire passes through one screw corresponding to the a+b+3th thread hole group each time, the wire passes through the loop formed at the screw by the second curved flexible support section corresponding to the circular truncated cone IV;

[0173] When the screw corresponding to the a+b+c+2th thread hole group and the screw corresponding to the a+b+3th thread hole group are both wound by the wire once, the wire is wound on the screw-(a+b+3)-1 again, and the stent end section corresponding to the circular cylinder III is prepared;

[0174] (9) The end of the wire is fixed on the stent end section corresponding to the circular cylinder III, and the structure preparation of the braiding-knitting segmented colonic nickel-titanium alloy stent is completed.

[0175] (10) After the product of step (9) and the mold are heat set at a temperature of 475-500 ℃ for 20-25 min, the mold is removed, and one end of the wire fixed on the screw-a-1 in step (2) is fixed on the stent end section corresponding to the circular cylinder I, thereby preparing the braiding-knitting segmented colonic nickel-titanium alloy stent.

[0176] As Figures 1-2 shown, the final prepared braiding-knitting segmented colo-nic nickel-titanium alloy stent tubular structure includes a stent main section 4, two ends of the stent main section 4 are connected with a first curved flexible support section 3, a second curved flexible support section 2 and a stent end section 1 in sequence respectively; the stent main section 4, the first curved flexible support section 3, the second curved flexible support section and the stent end section 1 are all obtained by braiding process, and the adjacent sections are connected by knitting process; the stent main section 4 and the stent end section 1 are cylindrical structures, the first curved flexible support section 3 and the second curved flexible support section 2 are circular truncated cone structures, the first curved flexible support section 3 and the second curved flexible support section 2 are connected to form a V-shaped structure through their small ends, and the V-shaped structure is formed by the stent main section 4 and each stent end section 1 through two loops nesting with each other; the opening angle of the V-shaped structure formed by the first curved flexible support section and the second curved flexible support section is 50°~130°; the radial strength of the stent main section is 4~10 N / mm 2 , the radial strength of the stent end section is greater than that of the stent main section; the length of the stent end section is 10~20 mm, and the length of the stent main section is 30~40 mm; the braiding density of the stent end section is 3~5 / cm, and the braiding density of the stent end section is 1~1.5 times that of the stent main section.

[0177] The preparation method of the braiding-knitting segmented colo-nic nickel-titanium alloy stent will be described below by using specific examples, and the specific steps are as follows:

[0178] Example 1

[0179] The preparation method of the braiding-knitting segmented colo-nic nickel-titanium alloy stent, the parameters are specifically selected as follows: the diameter of the cylinder I is 22 mm, and the small end diameter of the circular truncated cone I is 16 mm; a=4, b=7, c=4, i=17, j=13, m=5, q=2, and the overall braiding structure of the stent is shown in Figure 11 , and the specific steps are as follows:

[0180] (1) Preparation of the stent end section corresponding to the cylinder I;

[0181] One end of a metal wire is fixed on the screw-4-1,

[0182] and then passes through-1-3, -4-5, -1-7, -4-9, -1-11, -4-13, -1-2, -4-4, -1-6, -4-8, -1-10, -4-12, -1-1, -4-3, -1-5, -4-7, -1-9, -4-11, -1-13, -4-2, -1-4, -4-6, -1-8, -4-10, -1-12, -4-1 in sequence, so as to obtain the stent end section corresponding to the cylinder I; wherein d=1, e=3.

[0183] (2) Preparation of the second curved flexible support section corresponding to the circular truncated cone I;

[0184] After the metal wire in step (1) passes through the screw-4-1, it is wound around -5-2, -4-3, -5-4, -4-5, -5-6, -4-7, -5-8, -4-9, -5-10, -4-11, -5-12, -4-13, -5-1, -4-2, -5-3, -4-4, -5-5, -4-6, -5-7, -4-8, -5-9, -4-10, -5-11, -4-12, -5-13, -4-1 in sequence, thereby obtaining the second curved flexible support section corresponding to the circular truncated cone I;

[0185] (3) Preparation of the first curved flexible support section corresponding to the circular truncated cone II;

[0186] After the metal wire in step (2) passes through the screw-4-1, it is wound around -6-2, -5-3, -6-4, -5-5, -6-6, -5-7, -6-8, -5-9, -6-10, -5-11, -6-12, -5-13, -6-1, -5-2, -6-3, -5-4, -6-5, -5-6, -6-7, -5-8, -6-9, -5-10, -6-11, -5-12, -6-13, -5-1 in sequence, thereby obtaining the first curved flexible support section corresponding to the circular truncated cone II;

[0187] (4) Preparation of the main support section corresponding to the circular cylinder II;

[0188] After the metal wire in step (3) passes through the screw-5-1, it is wound around -12-6, -6-11, -12-3, -6-8, -12-13, -6-5, -12-10, -6-2, -12-7, -6-12, -12-4, -6-9, -12-1, -6-6, -12-11, -6-3, -12-8, -6-13, -12-5, -6-10, -12-2, -6-7, -12-12, -6-4, -12-9, -6-1 in sequence, thereby obtaining the main support section corresponding to the circular cylinder II;

[0189] (5) Preparation of the first curved flexible support section corresponding to the circular truncated cone III;

[0190] The metal wire of step (4) is wound around screw-6-1, and then successively around -13-2, -12-3, -13-4, -12-5, -13-6, -12-7, -13-8, -12-9, -13-10, -12-11, -13-12, -12-13, -13-1, -12-2, -13-3, -12-4, -13-5, -12-6, -13-7, -12-8, -13-9, -12-10, -13-11, -12-12, -13-13, -12-1, thereby obtaining the first curved flexible support segment corresponding to the circular truncated cone III;

[0191] (6) Preparation of the second curved flexible support segment corresponding to the circular truncated cone IV;

[0192] The metal wire of step (5) is wound around screw-12-1, and then successively around -14-2, -13-3, -14-4, -13-5, -14-6, -13-7, -14-8, -13-9, -14-10, -13-11, -14-12, -13-13, -14-1, -13-2, -14-3, -13-4, -14-5, -13-6, -14-7, -13-8, -14-9, -13-10, -14-11, -13-12, -14-13, -13-1, thereby obtaining the second curved flexible support segment corresponding to the circular truncated cone IV;

[0193] (7) Preparation of the support end segment corresponding to the cylinder III;

[0194] The metal wire of step (6) is wound around screw-14-1, and then successively around -17-3, -14-5, -17-7, -14-9, -17-11, -14-13, -17-2, -14-4, -17-6, -14-8, -17-10, -14-12, -17-1, -14-3, -17-5, -14-7, -17-9, -14-11, -17-13, -14-2, -17-4, -14-6, -17-8, -14-10, -17-12, -14-1, thereby obtaining the support end segment corresponding to the cylinder III;

[0195] (8) The end of the metal wire is fixed on the support end segment corresponding to the cylinder III, thereby completing the preparation of the structure of the braiding-knitting segmented colorectal nickel-titanium alloy stent.

[0196] (9) After the product of step (8) and the mold are heat set at a temperature of 500 ℃ for 25 min, the mold is removed, and one end of the metal wire fixed on screw-3-1 in step (1) is fixed on the support end segment corresponding to the cylinder I, thereby obtaining the braiding-knitting segmented colorectal nickel-titanium alloy stent.

[0197] The finally prepared braiding-knitting segmented colorectal nickel-titanium alloy stent tubular structure comprises a stent main section, and first and second curved flexible support sections and stent end sections connected in sequence at both ends of the stent main section; the stent main section, the first and second curved flexible support sections and the stent end sections are obtained by braiding, and adjacent sections are connected by knitting; the stent main section and the stent end sections are cylindrical structures, the first and second curved flexible support sections are circular table structures, the first and second curved flexible support sections are connected by small ends to form a V-shaped structure, and the V-shaped structure is formed by mutual nesting of the stent main section and each stent end section through two loops; the V-shaped structure formed by the first curved flexible support section and the second curved flexible support section has an opening angle of 50°; the radial strength of the stent main section is 4.47 N / mm 2 , the radial strength of the stent end section is 6.02 N / mm 2 ; the length of the stent end section is 15 mm, and the length of the stent main section is 40 mm; the braiding density of the stent end section is 3 / cm, and the braiding density of the stent end section is 1.2 times that of the stent main section.

[0198] The anti-migration test uses a silica gel tube with a length of 10 mm and the same structure size to test the experimental sample and the control sample, and the results show that the force required for the braiding-knitting segmented colorectal nickel-titanium alloy stent (i.e. the experimental sample) to migrate is increased by 19.3% compared with the commercial stent (CDT2006, i.e. the control sample), and when the stent end section and the two curved flexible support sections are deformed to produce a 10 mm displacement caused by pulling, the other part of the relative end section, i.e. the main section, is still in the original position, and the anti-migration performance is good.

[0199] The bending flexibility test results show that the bending flexibility of the braiding-knitting segmented colorectal nickel-titanium alloy stent (i.e. the experimental sample) is increased by 9.6% compared with the commercial stent (i.e. the control sample), and the bending flexibility is good.

[0200] The diameter of 0.28 mm medical nickel-titanium alloy wire is segmented on the designed stent knitting mold, and the tubular fabric is made alternately by each root, so that it forms a stable structure. The diameter of the different segment mold is the same as the inner diameter of the colon stent to be prepared, each segment is prepared in order, and the structure of adjacent segments is different. The stent end segment 1 is the key part to ensure the fixation of the stent, the diameter is the largest, up to 22 mm, the stent main segment 4 is the main segment of the stent for expanding the obstruction, the diameter is 18 mm, the first curved flexible support segment and the second curved flexible support segment 2 can provide the bending flexibility of the stent end segment 1 and the stent main segment 4, the minimum diameter of the joint between the first curved flexible support segment 3 and the second curved flexible support segment 2 is 16 mm. The nickel-titanium alloy wire on each spool wound with nickel-titanium alloy wire is 12 equally spaced, the helix angle and the tension of the nickel-titanium alloy wire are controlled according to the required radial support performance, the helix angle of the stent end segment 1 and the stent main segment 4 is 60°, the helix angle of the first curved flexible support segment 3 and the second curved flexible support segment 2 is 45°, each segment will be knitted in turn, and tensioned to the screw of the adjacent segment.

[0201] As shown in Figure 2 and Figure 3 , the first curved flexible support segment 3 and the second curved flexible support segment 2 are connected by knitting at the minimum diameter of the stent 6 to form a loop 13, which can provide radial support performance and bending flexibility to the stent main segment; the joint curved connection part 7 between the first curved flexible support segment 3 and the maximum diameter of the stent end segment 8 is made by knitting, which can resist migration; the length of the stent main segment 4 depends on the length of the colon obstruction in the patient's body, and the segmented tubular fabric is made by knitting method, and the whole structure is connected by knitting process. The stent end segment 1 is not affected by the load of the intermediate segment, has good fatigue resistance, and provides radial support performance; the stent main segment 4 can maintain good external radial force when bending with intestinal peristalsis compared with continuous knitting. The first curved flexible support segment 3 not only prevents the lumen from slipping at the second curved flexible support segment 2, but also helps the bending flexible connection of the stent end segment 1 and the second curved flexible support segment 2. Similarly, the second curved flexible support segment 2 also provides a bending flexible connection between the first curved flexible support segment 3 and the stent main segment 4, and prevents slipping at the first curved flexible support segment 3. The two curved flexible support segments provide bending flexibility while reducing radial support performance to avoid perforation; the prepared fabric is washed, dried together with the mandrel, and then heat treated at 500°C to obtain a knitted-knitted segmented colon nickel-titanium alloy stent; due to the segmented design, each segment has different radial support performance and diameter, and the stent prepared by the above method can integrate the required bending flexibility and radial support performance.

[0202] As shown in Figure 13As shown, a single nickel-titanium alloy wire is woven back and forth from top to bottom along the mold designed in this invention. Starting from the upper end section, the nickel-titanium alloy wire is hooked around the end section screw and the end section connecting section screw every other screw (i.e., the braided part of the bracket end section). The end section connecting section screw and the first curved flexible support section, the first curved flexible support section and the second curved flexible support section, the second curved flexible support section and the main section of the bracket are hooked in the same way, that is, every other screw. Unlike before, when these three hooking nodes α, β and γ are woven from bottom to top, they are presented in the form of knitted loops (i.e., cross hooking). The braiding method of the main section of the bracket is the same as that of the end section.

[0203] The resulting braided-knitted segmented colorectal nickel-titanium alloy stent exhibits significantly greater radial compressive strength at stent end segment 1, by 20.4%, compared to an equivalent fully braided stent of the same size and number of wires.

[0204] like Figure 4 As shown, under colonoscopy guidance, a guidewire is inserted along the gap of the mass, and then the stent delivery system 14 is pushed in. After confirming that the stent has passed through the narrowed segment and exceeded the upper edge of the mass by 2-3 cm, the braided-knitted segmented colorectal nickel-titanium alloy stent 15 prepared by the above method is released. After the stent is delivered to the target site, it will generate a continuous expansion force to support the narrowed part of the intestine, restoring patency to the narrowed part. This stent also has bending flexibility, reducing the occurrence of perforation. After the obstruction is relieved, surgical treatment can continue.

[0205] The above-mentioned "V-shaped" structural design is as follows: Figure 8 As shown, this is achieved by changing the diameter at the connection points of different support segments. The diameters of each segment are different, with connection points i and l having smaller diameters (e.g., ...). Figure 5 As shown, the first flexible support segment 3 and the second flexible support segment 2 are connected by knitted loops to form a "V-shaped" structure that is concave inward. This structure can improve the bending flexibility between the larger segments of the stent (i.e., the stent end segment 1 and the stent main segment 4), reducing the risk of stent migration or deformation. The targeted "V-shaped" segment connection design proposed in this invention is a key feature for enhancing the overall bending flexibility of the intestinal stent and generating a continuous and gentle radial expansion force to solve intestinal stenosis.

[0206] In addition to the "arrangement and configuration of each segment", the entire support structure of this invention can be made from a single monofilament, and the monofilament can extend to different segments to achieve interconnection, such as... Figure 9 As shown. In Figure 5 In the process, while completing the weaving of each segment, the monofilament performs coil weaving and cyclic reversal at connection points such as h, i, j, k, l, and m, and then proceeds to weave the next segment.

[0207] The braiding-knitting segmented colorectal nickel-titanium alloy stent of the present application has the following advantages:

[0208] (1) "V-shaped" structure: the "V-shaped" structure proposed by the present application can increase the bending flexibility of the stent at both ends and the middle main stent through the interlocking loops, and when the stent expands to form a stable structure at the intestinal stenosis, the sliding locking effect of the loops can prevent the stent from migrating;

[0209] As shown in Figure 16 , the "V-shaped" structure helps to maximize the curvature limit of the stent extension, thereby forming an outer curvature during bending. Within this bending length range, the bending load comes entirely from the frictional sliding of the loops and the extension of the V-shaped to the inverted n-shaped, resulting in elastic extension, and the two looped loops at the loop connection can be hook-shapedly connected to each other and laterally extended by 5 mm, thus having better bending flexibility.

[0210] (2) Interlocking of knitted loops: when the stent is bent, the loop ends of the outer side (u) and the inner side (v) of the stent slide relative to each other until the outer side loops hook the contact point (z) and cannot continue to slide, reaching their respective limits, so that the sliding limit is increased and the flexibility is enhanced;

[0211] (3) Compared with the prior art, as shown in Figure 10 , the stent proposed by the present application has different radial strengths at different segments, and the edge (flange segment) part has greater strength than the main part (main segment). With the shortening of the length, the radial strength of the main part is greater. For an intestinal stent, as the length of the stent main part is shortened, its radial strength is significantly enhanced, because the short stent structure is more stable and is less prone to axial buckling or local instability, and the stress distribution is more uniform and the structural rigidity is stronger under radial loading. Therefore, the stent with shorter length exhibits higher strength in resisting radial compression. The length of the stent main segment depends on the size of the intestinal obstruction or stenosis tissue in the body. When the stent is bent, the angle of the V-shaped structure formed by the interlocking loops (i.e., the interlocking loop structure 5) can be changed, and the loop gap allows the loops to slide and bend, giving the stent good bending compliance and significantly enhancing the anti-migration performance of the stent as a whole;

[0212] (4) The arrangement and configuration of different segments used in the present application make each segment of the stent have different radial compression performance, which can reduce the discomfort of the patient caused by excessive expansion of the stent at the stenosis.

[0213] As shown in Figure 17As shown, the loop shape of the stent knitted part in different states is shown, the loop of the stent has a large gap in the normal state, the migration resistance of the stent is mainly realized through the friction resistance of two intersection points of the loop, and when the stent is bent, the loops slide relative to each other, the gap between the loops becomes small, the loops are hooked, and the sliding resistance in the radial direction of the stent is generated, thereby significantly enhancing the migration resistance of the stent.

[0214] As Figure 18 shown, it is a bending flexibility comparison diagram of the stent of the present application and the existing ordinary stent, wherein ①, is the outer bending arc corresponding to the "V" shaped structure of the stent of the present application when the stent is bent, and the inner bending arc, 、 is a simple structure model of the stent of the present application and a simple structure model of the ordinary stent on the market, 、 is the inner and outer bending degree of the connection between the end section and the main section of the stent of the present application, 、 is the inner and outer bending degree of the connection between the end section and the main section of the ordinary stent, by and 、 and , it can be directly observed that the "V" shaped structure constructed by the stent knitting method of the present application gives the stent a larger bending angle, that is, gives the stent a better bending compliance.

Claims

1. A braided-knitted segmented colonic nitinol stent, in a tubular structure, characterized in that: The stent main section is connected with a first curved flexible support section, a second curved flexible support section and a stent end section in sequence at both ends of the stent main section. The stent main section, the first curved flexible support section, the second curved flexible support section and the stent end section are obtained by knitting process, and adjacent sections are connected by knitting process. The stent main section and the stent end section are cylindrical structures, and the first curved flexible support section and the second curved flexible support section are circular truncated cone structures. The radial strength of the main section of the stent is 4-10 N / mm 2 The radial strength of the end section of the stent is greater than that of the main section of the stent.

2. The braided-knitted segmented colonic Nitinol stent according to claim 1, characterized in that, The length of the stent end section is 10-20 mm, and the length of the stent main section is 30-40 mm.

3. The braided-knitted segmented colonic Nitinol stent of claim 1, wherein, The opening angle of the V-shaped structure formed by the first curved flexible support section and the second curved flexible support section is 50-130°.

4. The braided-knitted segmented colonic Nitinol stent of claim 2, wherein, The knitting density of the stent end section is 3-5 / cm, and the knitting density of the stent end section is 1-1.5 times that of the stent main section.

5. The braided-knitted segmented colonic Nitinol stent of claim 1, wherein, The material of the braided-knitted segmented colorectal nickel-titanium alloy stent is a metal wire.

6. The braided-knitted segmented colonic Nitinol stent of claim 5, wherein, The metal wire is a nickel-titanium alloy wire.

7. A method of making a braided-knitted segmented colonic nitinol stent according to any one of claims 1 to 6, characterized in that: The braided-knitted segmented colorectal nickel-titanium alloy stent is integrally formed by braiding a stent end section, a second curved flexible support section, a first curved flexible support section, a stent main section, another first curved flexible support section, another second curved flexible support section and another stent end section in sequence.

8. The method of manufacturing a braided-knitted segmented colonic nitinol stent according to claim 7, wherein, The specific steps are as follows: (1) Preparation of the mold; The mold is formed by connecting a cylinder I, a circular truncated cone I, a circular truncated cone II, a cylinder II, a circular truncated cone III, a circular truncated cone IV and a cylinder III in sequence; wherein the diameter of the cylinder I, the large end diameter of the circular truncated cone I, the large end diameter of the circular truncated cone II, the diameter of the cylinder II, the large end diameter of the circular truncated cone III, the large end diameter of the circular truncated cone IV and the diameter of the cylinder III are equal, the small end diameter of the circular truncated cone I, the small end diameter of the circular truncated cone II, the small end diameter of the circular truncated cone III and the small end diameter of the circular truncated cone IV are equal; one end of the cylinder I is fixedly connected with the large end of the circular truncated cone I, the small end of the circular truncated cone I is fixedly connected with the small end of the circular truncated cone II, and the large end of the circular truncated cone II is fixedly connected with one end of the cylinder II; the other end of the cylinder II is fixedly connected with the large end of the circular truncated cone III, the small end of the circular truncated cone III is fixedly connected with the small end of the circular truncated cone IV, and the large end of the circular truncated cone IV is fixedly connected with one end of the cylinder III; Along the axial direction of the mold, the peripheral surface of the mold is provided with i threaded hole groups, each threaded hole group including j threaded holes, and the j threaded holes are uniformly distributed along the circumferential direction of the mold; wherein the cylindrical I is provided with a threaded hole group, the cylindrical II is provided with b threaded hole groups, the cylindrical III is provided with c threaded hole groups, the connection part of the circular table I and the circular table II is provided with 1 threaded group, and the connection part of the circular table III and the circular table IV is provided with 1 threaded group; Among the a threaded hole groups provided on the cylindrical I, one threaded hole group is located at the connection part of the cylindrical I and the circular table I; Among the b threaded hole groups provided on the cylindrical II, one threaded hole group is located at the connection part of the cylindrical II and the circular table II, and one threaded hole group is located at the connection part of the cylindrical II and the circular table III; a+b+c+2=i, j≥9; All threaded holes on the mold are respectively and individually screw fixedly connected with a screw, and the threaded holes on the mold are arrayed; (2) Preparation of the support end section corresponding to the cylindrical I; Record a threaded hole on a threaded hole group as the first threaded hole, and the last threaded hole in the clockwise direction from the first threaded hole is the jth threaded hole; Record the threaded hole group farthest from the cylindrical III on the cylindrical I as the first threaded hole group, and the last threaded hole group in the direction from the cylindrical I to the cylindrical III from the first threaded hole group is the ith threaded hole group; wherein the screw corresponding to the yth threaded hole of the xth threaded hole group is marked as screw-x-y, 1≤x≤i, 1≤y≤j; One end of a metal wire is fixed on the screw-a-1, and the other end is wound back and forth around one screw corresponding to the first threaded hole group and one screw corresponding to the ath threaded hole group; The screw corresponding to the first threaded hole group and the screw corresponding to the ath threaded hole group are both wound by the metal wire once. Wherein, the winding rule of the end of the metal wire after being fixed on the screw-a-1 is: when y takes any value, the metal wire first winds around the screw-1-y, then winds around the screw-a-f(y+d+1), and then winds around the screw-1-f(y+e+1); d is the number of screws spaced between the two adjacent screws on the first threaded hole group and the ath threaded hole group that are first wound by the metal wire along the circumferential direction; e is the number of screws spaced between the two adjacent screws on the first threaded hole group or the ath threaded hole group that are first wound by the metal wire; The expression of function f(k) is: f(k)=(k-j)×θ(k-j)+k×[1-θ(k-j)]; θ(G) is a step function, θ(G) is 1 when G>0, and θ(G) is 0 when G≤0; Wherein, j is an odd number, e≥3, j≥2e+2, and d When the metal wire is wound on the screw-a-1, the support end section corresponding to the cylindrical I is prepared; (3) Preparation of the second curved flexible support section corresponding to the circular table I; After the metal wire is wound around the screw-a-1 in step (2), it is wound back and forth around one screw corresponding to the a+1th threaded hole group and one screw corresponding to the ath threaded hole group; The screw corresponding to the a+1th threaded hole group and the screw corresponding to the ath threaded hole group are both wound by the metal wire once. Wherein, the winding rule of the metal wire after winding around the screw-a-1 is: when y takes any value, the metal wire first winds around the screw-(a+1)-y, then winds around the screw-a-f(y+1), and then winds around the screw-(a+1)-f(y+2); When the metal wire passes through the screw corresponding to the first flexible support segment of the cylindrical column I each time, the metal wire passes through the coil formed by the bracket end segment corresponding to the cylindrical column I at the screw; When the screw corresponding to the first flexible support segment of the cylindrical column I and the screw corresponding to the second flexible support segment of the cylindrical column I are both wound by the metal wire once, the metal wire is wound around the screw-a-1 again, that is, the second flexible support segment of the cylindrical column I is prepared; (4) Preparation of the first flexible support segment of the circular column II; After the metal wire in step (3) winds around the screw-a-1, it first winds around the screw-(a+2)-2, and then winds back and forth around the screw corresponding to the a+1 th thread hole group and the screw corresponding to the a+2 th thread hole group; the screw corresponding to the a+1 th thread hole group and the screw corresponding to the a+2 th thread hole group are both wound by the metal wire once; Wherein, the winding rule of the metal wire after winding around the screw-(a+2)-2 is: when y takes any value, the metal wire first winds around the screw-(a+1)-y, then winds around the screw-(a+2)-f(y+1), and then winds around the screw-(a+1)-f(y+2); When the metal wire passes through the screw corresponding to the first flexible support segment of the cylindrical column I each time, the metal wire passes through the coil formed by the bracket end segment corresponding to the cylindrical column I at the screw; When the screw corresponding to the first flexible support segment of the cylindrical column I and the screw corresponding to the second flexible support segment of the cylindrical column I are both wound by the metal wire once, the metal wire is wound around the screw-a-1 again, that is, the second flexible support segment of the cylindrical column I is prepared; (5) Preparation of the bracket main segment corresponding to the cylindrical column II; After the metal wire in step (4) winds around the screw-(a+1)-1, it first winds around the screw-(a+b+1)-6, and then winds around the screw-(a+2)-11, and then winds back and forth around the screw corresponding to the a+2 th thread hole group and the screw corresponding to the a+b+1 th thread hole group; the screw corresponding to the a+2 th thread hole group and the screw corresponding to the a+b+1 th thread hole group are both wound by the metal wire once; Wherein, the winding rule of the metal wire after winding around the screw-(a+2)-11 is: when y takes any value, the metal wire first winds around the screw-(a+2)-y, then winds around the screw-(a+b+1)-f(y+m), and then winds around the screw-(a+2)-f(y+2m); Wherein, m-1 is the number of screws between the two adjacent screws that are wound by the metal wire in the a+2 th thread hole group and the a+b+1 th thread hole group in sequence; 2m-1 is the number of screws between the two adjacent screws that are wound by the metal wire in the a+2 th thread hole group or the a+b+1 th thread hole group in sequence; 2m-1≥7; When the metal wire passes through the screw corresponding to the first flexible support segment of the cylindrical column I each time, the metal wire passes through the coil formed by the bracket end segment corresponding to the cylindrical column I at the screw; When the screw corresponding to the a+2th screw hole group and the screw corresponding to the a+b+1th screw hole group are both wound by the wire once, and the wire is wound on the screw-(a+2)-1 again, the first curved flexible support section corresponding to the circular cylinder II is prepared; (6) Preparation of the first curved flexible support section corresponding to the circular table III; After the wire of step (5) is wound on the screw-(a+2)-1, it is first wound on the screw-(a+b+2)-2, and then wound on the screw-(a+b+1)-3, and then wound back and forth on one screw corresponding to the a+b+2th screw hole group and one screw corresponding to the a+b+1th screw hole group; the screw corresponding to the a+b+2th screw hole group and the screw corresponding to the a+b+1th screw hole group are both wound by the wire once; Wherein, the winding rule after the wire is wound on the screw-(a+b+1)-3 is: when y takes any value, the wire is first wound on the screw-(a+b+1)-y, and then wound on the screw-(a+b+2)-f(y+1), and then wound on the screw-(a+b+1)-f(y+2); When the screw corresponding to the a+2th screw hole group and the screw corresponding to the a+b+1th screw hole group are both wound by the wire once, and the wire is wound on the screw-(a+2)-1 again, the first curved flexible support section corresponding to the circular cylinder II is prepared; (6) Preparation of the first curved flexible support section corresponding to the circular table III; After the wire of step (5) is wound on the screw-(a+2)-1, it is first wound on the screw-(a+b+2)-2, and then wound on the screw-(a+b+1)-3, and then wound back and forth on one screw corresponding to the a+b+2th screw hole group and one screw corresponding to the a+b+1th screw hole group; the screw corresponding to the a+b+2th screw hole group and the screw corresponding to the a+b+1th screw hole group are both wound by the wire once; Wherein, the winding rule after the wire is wound on the screw-(a+b+2)-3 is: when y takes any value, the wire is first wound on the screw-(a+b+2)-y, and then wound on the screw-(a+b+3)-f(y+1), and then wound on the screw-(a+b+2)-f(y+2); When the screw corresponding to the a+2th screw hole group and the screw corresponding to the a+b+1th screw hole group are both wound by the wire once, and the wire is wound on the screw-(a+2)-1 again, the first curved flexible support section corresponding to the circular cylinder II is prepared; (6) Preparation of the first curved flexible support section corresponding to the circular table III; After the wire of step (5) is wound on the screw-(a+2)-1, it is first wound on the screw-(a+b+2)-2, and then wound on the screw-(a+b+1)-3, and then wound back and forth on one screw corresponding to the a+b+2th screw hole group and one screw corresponding to the a+b+1th screw hole group; the screw corresponding to the a+b+2th screw hole group and the screw corresponding to the a+b+1th screw hole group are both wound by the wire once; Wherein, the winding rule after the wire is wound on the screw-(a+b+2)-3 is: when y takes any value, the wire is first wound on the screw-(a+b+2)-y, and then wound on the screw-(a+b+3)-f(y+1), and then wound on the screw-(a+b+2)-f(y+2); When the screw corresponding to the a+2th screw hole group and the screw corresponding to the a+b+1th screw hole group are both wound by the wire once, and the wire is wound on the screw-(a+2)-1 again, the first curved flexible support section corresponding to the circular cylinder II is prepared; (8) Preparation of the bracket end section corresponding to the circular cylinder III; After the metal wire in step (7) is wound around the screw-(a+b+3)-1, the metal wire is first wound around the screw-(a+b+c+2)-3, then wound around the screw-(a+b+3)-5, and then wound back and forth around one screw corresponding to the a+b+c+2 th screw hole group and one screw corresponding to the a+b+3 th screw hole group; the screw corresponding to the a+b+c+2 th screw hole group and the screw corresponding to the a+b+3 th screw hole group are both wound by the metal wire once; wherein, after the metal wire is wound around the screw-(a+b+3)-5, the winding rule is that when y takes any value, the metal wire is first wound around the screw-(a+b+3)-y, then wound around the screw-(a+b+c+2)-f(y+q), and then wound around the screw-(a+b+3)-f(y+2q); wherein, q-1 is the number of screws between two adjacent screws corresponding to the a+b+c+2 th screw hole group and the a+b+3 th screw hole group that are wound by the metal wire in sequence, 2q-1 is the number of screws between two adjacent screws corresponding to the a+b+c+2 th screw hole group or the a+b+3 th screw hole group that are wound by the metal wire in sequence, and 2q-1≥3; when the metal wire passes through one screw corresponding to the a+b+3 th screw hole group each time, the metal wire passes through the loop formed by the second curved flexible support segment corresponding to the circular truncated cone IV at the screw; after the screw corresponding to the a+b+c+2 th screw hole group and the screw corresponding to the a+b+3 th screw hole group are both wound by the metal wire once, when the metal wire is wound around the screw-(a+b+3)-1 again, the bracket end segment corresponding to the cylinder III is obtained; (9) fixing the end of the metal wire on the bracket end segment corresponding to the cylinder III to complete the preparation of the braiding-knitting segmented colonic nickel-titanium alloy stent structure; (10) after the product of step (9) and the mold are heat set, the mold is removed, and one end of the metal wire fixed on the screw-a-1 in step (2) is fixed on the bracket end segment corresponding to the cylinder I, thereby obtaining the braiding-knitting segmented colonic nickel-titanium alloy stent.

9. The method of claim 8, wherein the braided-knitted segmented colonic Nitinol stent is prepared by the steps of: The temperature of the heat treatment is 475-500℃, and the time is 20-25 min.

10. The method of claim 9, wherein the braided-knitted segmented colonic Nitinol stent is prepared by the steps of: 3≤a≤5, 5≤b≤12, 3≤c≤5, 12≤j≤32, 3≤d≤5, 1≤e≤3, 7≤2m-1≤21, and 3≤2q-1≤5.

11. The method of claim 10, wherein the braided-knitted segmented colonic Nitinol stent is prepared by the steps of: In the mold, the diameter of the cylinder I is 22-30 mm, and the small end diameter of the circular truncated cone I is 16-20 mm.

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