Multi-level composite spiral micro / nano fiber artificial ligament

Abstract

The utility model discloses a multi-level composite spiral type micro / nano-fiber artificial ligament which is formed by twisting micron-level or nano-level fibers made of biodegradable materials into fiber bundles in a multi-level mode, and the adjacent twisting levels are twisted in the opposite direction. A plurality of micron and nano channels which are composed of fiber bundles and have the physical induction characteristic are formed on the surface of the artificial ligament, the diameter of a single micro-nano fiber bundle ranges from 350 nm to 52 microns, and the diameter of the artificial ligament ranges from 1 mm to 5.5 mm. The diameter of the artificial ligament can be flexibly adjusted and controlled, diversified design of the ligament structure is achieved, and various ligament requirements are met. The mechanical property of the graft is similar to that of a human ligament, the graft can provide the function of a normal ligament and meet the requirement of normal physiological activities of people, the graft is good in biocompatibility, regenerated new ligaments are allowed to grow in after the graft is implanted into the human body, the graft is degradable, degradation products of the graft are harmless to the human body and can be discharged out of the body, and the effects of replacing damaged ligaments and promoting tissue regeneration and reconstruction can be achieved.

Description

Technical Field

[0001] This utility model belongs to the field of medical materials technology, and in particular relates to a multi-level composite spiral micro / nanofiber artificial ligament. Background Technology

[0002] Tendon and ligament injuries are among the most common musculoskeletal disorders, and the medical field has long been dedicated to solving the healing challenges of tendon-ligament injuries. Ligaments and tendons, composed of fibrous connective tissue, are crucial for joint movement and stability. Ligaments connect bones, while tendons connect muscles to bones. Because these tissues transmit high tensile forces, they must be strong, flexible, and stable. Alarmingly, with increasing life expectancy, the probability of adults developing tendon-related diseases will significantly increase, posing a serious challenge to the healthcare system.

[0003] Currently, autologous and allogeneic grafts are considered the best options for tendon and ligament reconstruction surgery because they are inherently bioactive and can promote cell proliferation and new tissue growth. However, they are often scarce and may pose potential risks, such as the ease with which the donor site can develop immune responses and spread of disease. Furthermore, the surgery is expensive and may lead to unexpected complications and secondary damage. Achieving strong and durable high-performance grafts remains an unmet need.

[0004] Biomimetic fiber membranes that mimic the structural changes of the natural tendon-bone interface are ideal scaffolds for tendon-bone tissue repair. Studies have shown that electrospinning technology can create structures that mimic the arrangement of natural fibers, and this has been extensively researched. Currently, there are many types of scaffolds, ligaments, and tendons used to prepare artificial biomimetic tendon-bone tissues, with varying manufacturing processes, such as the following patented technologies:

[0005] CN 114305792 A discloses a ligament regeneration scaffold with layer-by-layer induction properties, which is woven from yarns with different degradation cycles through multidimensional multi-layer textile forming. The nanofiber induction layer is prepared by electrospinning a composite spinning solution with a micron fiber reinforcement layer as the receiving substrate. The composite spinning solution contains polymer materials and bioactive components.

[0006] CN 113413236 A discloses a hollow artificial ligament, which is a tubular structure woven from braided threads. The artificial ligament has a cavity in the center for accommodating transplanted tissue. Large-pore meshes are provided between the braided threads. The pore size of the mesh is at least large enough to allow the transplanted tissue to fully contact the autologous tissue, which is beneficial for synovial growth, tissue vascularization, and provides a certain mechanical strength in the early tissue healing process.

[0007] CN 118390218 A discloses a weft yarn for artificial ligaments, its preparation method, and an artificial ligament. The artificial ligament has a cylindrical structure, with a first braided section, an intra-articular free filament section, and a second braided section sequentially connected along the axial direction. The intra-articular free filament section includes multiple weft yarns extending along the axial direction of the cylindrical structure. The fineness of the weft yarns is 1000D-3000D / 1-100F, and the mechanical strength of the weft yarns is 75-300N. This invention improves the mechanical strength of a single yarn forming the intra-articular free filament section of the artificial ligament, thereby reducing the number of yarns in the intra-articular free filament section. This solves the problem of knee joint synovitis caused by friction between the artificial ligament and debris during artificial ligament reconstruction, and also reduces the degree of adhesion between the free filament section and tissue, reducing the probability of adhesion. This addresses the clinical problems of inflammatory reactions and prolonged operation time caused by the difficulty in removing adhesions between free filaments and tissue during revision surgery.

[0008] As is well known in the medical field, the human body has eight ligaments: the knee ligament, inguinal ligament, coracoacromial ligament, radial and ulnar collateral ligaments of the elbow, ankle ligament, uterine ligament, and cruciate ligaments. The width, thickness, and mechanical requirements for providing stability to bones and other human tissues vary depending on the location of the ligament. Therefore, while the artificial ligament products prepared by the aforementioned patent have good biocompatibility, can promote cell proliferation and adhesion, and possess a certain degree of mechanical strength, their manufacturing process is complex, often involving woven mesh structures, resulting in high costs. Furthermore, the lack of structural diversity prevents flexible adjustment of the required shape and mechanical properties for different ligaments, hindering accurate matching to the physiological characteristics of ligaments in different parts of the body and making it difficult to achieve the actual function of artificial ligaments.

[0009] In summary, how to flexibly and controllably adjust the actual shape, structure, size, and mechanical strength of ligaments required for different parts of the human body while ensuring the basic biocompatibility and biodegradability of artificial ligaments, and to simulate the physiological properties and basic functions of ligaments in different parts of the human body to the greatest extent possible, so as to achieve diversified production, has become a problem that technicians in the field of medical materials artificial ligaments urgently need to solve. Summary of the Invention

[0010] In view of the shortcomings of the existing technology, the technical problem to be solved by this utility model is to provide a multi-level composite spiral micro / nanofiber artificial ligament with simple structure, flexible adjustment of structure and mechanical properties according to the needs of different joint tissues in the human body, and low cost.

[0011] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: a multi-level composite spiral micro / nanofiber artificial ligament, which is composed of micron- or nano-sized fibers made of biodegradable materials, which are twisted into fiber bundles through multiple stages. The adjacent twisting stages are twisted in opposite directions, forming a number of micron and nano channels with physical induction properties composed of fiber bundles on the surface of the artificial ligament. The diameter of a single micro / nanofiber bundle is 350nm-52μm, and the diameter of the artificial ligament is 1-5.5mm.

[0012] The aforementioned multi-level composite spiral micro / nanofiber artificial ligament is made of micron-sized fibers made of biodegradable materials through multi-level twisting. The number of micron-sized fiber bundles that make up the artificial ligament is 24-100, of which the diameter of a single micron-sized fiber bundle is 22-52μm, and the diameter of the artificial ligament is 1.5-5.5mm.

[0013] The aforementioned multi-level composite spiral micro / nanofiber artificial ligament comprises 24-40 micron-sized fiber bundles, each with a diameter of 22-28 μm. These bundles are formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with 4-6 S-twists, tertiary twisting with 3 or 4 Z-twists, and quaternary twisting with 2 S-twists. The primary twist is 50 twists / 10cm, the secondary twist is 35 twists / 10cm, the tertiary twist is 30 twists / 10cm, and the quaternary twist is 17.5 twists / 10cm. The diameter of the artificial ligament is 1.5-2.5 mm.

[0014] The aforementioned multi-level composite spiral micro / nanofiber artificial ligament comprises 80-100 micron-sized fiber bundles, each with a diameter of 43-52 μm. These bundles are formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with 5-10 S-twists, tertiary twisting with 2-4 Z-twists, and quaternary twisting with 4 or 5 S-twists. The primary twist is 50 twists / 10cm, the secondary twist is 35 twists / 10cm, the tertiary twist is 30 twists / 10cm, and the quaternary twist is 12 twists / 10cm. The diameter of the artificial ligament is 4.5-5.5 mm.

[0015] The aforementioned multi-level composite spiral micro / nanofiber artificial ligament is made of nanofibers made of biodegradable materials through multi-level twisting. The number of nanofiber bundles that make up the artificial ligament is 24-100, of which the diameter of a single nanofiber bundle is 350-780nm, and the diameter of the artificial ligament is 1-5mm.

[0016] The aforementioned multi-level composite spiral micro / nanofiber artificial ligament comprises 24-40 nanofiber bundles, each with a diameter of 350-450 nm. These bundles are formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with 4-6 S-twists, tertiary twisting with 3 or 4 Z-twists, and quaternary twisting with 2 S-twists. The primary twist is 50 twists / 10cm, the secondary twist is 35 twists / 10cm, the tertiary twist is 30 twists / 10cm, and the quaternary twist is 17.5 twists / 10cm. The diameter of the artificial ligament is 1-2 mm.

[0017] The aforementioned multi-level composite spiral micro / nanofiber artificial ligament comprises 80-100 nanofiber bundles, each with a diameter of 720-780 nm. These bundles are formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with 5-10 S-twists, tertiary twisting with 2-4 Z-twists, and quaternary twisting with 4 or 5 S-twists. The primary twist is 50 twists / 10cm, the secondary twist is 35 twists / 10cm, the tertiary twist is 30 twists / 10cm, and the quaternary twist is 12 twists / 10cm. The diameter of the artificial ligament is 4-5 mm.

[0018] The advantages of this novel multi-layered composite spiral micro / nanofiber artificial ligament are as follows: By employing biodegradable micro / nanofibers, single micro / nanofiber bundles are twisted and then subjected to a multi-layered reverse-direction composite twisting process. Alternating twisting directions (Z / S twist) effectively avoids excessive tilting caused by twisting fibers in a single direction, allowing for flexible control of the artificial ligament's diameter and achieving diversified ligament structure design and significantly enhanced mechanical properties. The multi-layered composite spiral micro / nanofiber artificial ligament structure obtained by this invention can maximize its excellent characteristics, improving the structural diversity of the composite yarn while also endowing it with more superior properties. Its mechanical properties are similar to those of human ligaments, providing the function of normal ligaments, meeting the needs of normal physiological activities, and exhibiting good biocompatibility. After implantation, it can assist in inducing ligament regeneration. The graft is biodegradable, and its degradation products are harmless to the human body and can be eliminated from the body, achieving the effects of replacing damaged ligaments and promoting tissue regeneration and reconstruction. Attached Figure Description

[0019] Figure 1 This is a physical image of the multi-level composite spiral micro / nanofiber artificial ligament of this utility model;

[0020] Figure 2 A schematic diagram illustrating the fabrication process of multi-level composite spiral micro / nanofiber artificial ligaments;

[0021] Figure 3 This is a diagram of the twisting test during the production of multi-level composite spiral micro / nanofiber artificial ligaments.

[0022] Figure 4 SEM image of the composite twisting steps from primary fiber bundles to quaternary fiber bundles in the artificial ligament of this utility model;

[0023] Figure 5 A diagram showing the diameter differences of fiber bundles at various levels that make up an artificial ligament.

[0024] Figure 6 The images shown are physical and SEM images of the multi-level composite spiral 36-strand nanofiber artificial ligament prepared in Example 5.

[0025] Figure 7 The images shown are physical and SEM images of the multi-level composite spiral-shaped 90-strand nanofiber artificial ligament prepared in Example 11.

[0026] Figure 8 Comparative test results of the mechanical properties of the 36-strand micron and nanofiber artificial ligaments prepared in Examples 2 and 5, respectively;

[0027] Figure 9 The graph shows a comparison of the mechanical properties of the 90-strand micron and nanofiber artificial ligaments prepared in Examples 8 and 11, respectively. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] In this utility model, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or working state, specifically the directions shown in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms "first," "second," "third," etc., are used merely as illustrative purposes and do not impose numerical requirements or establish an order. The term "multiple" means "two or more".

[0030] like Figure 1 , 2 As shown in Figures 3 and 4, a multi-level composite spiral micro / nanofiber artificial ligament is formed by multi-level twisting of micron- or nano-sized fibers made of biodegradable materials into fiber bundles. The adjacent twisting stages are twisted in opposite directions, that is, the spiral structure obtained by alternating the twisting directions (Z / S twist) of two adjacent twisting stages improves its flexibility and stability. Several micron and nano channels with physical induction properties composed of fiber bundles are formed on the surface of the artificial ligament. The diameter of a single micro / nanofiber bundle is 350nm-52μm, and the diameter of the artificial ligament is 1-5.5mm.

[0031] In artificial ligaments made from micron-sized fibers through multi-stage twisting, the number of micron-sized fiber bundles ranges from 24 to 100, with each individual bundle having a diameter of 22-52 μm and the overall diameter of the artificial ligament being 1.5-5.5 mm. Similarly, in artificial ligaments made from nano-sized fibers through multi-stage twisting, the number of nano-sized fiber bundles also ranges from 24 to 100, with each bundle having a diameter of 350-780 nm and the overall diameter of the artificial ligament being 1-5 mm.

[0032] The preparation method includes the following steps:

[0033] (1) A primary structure of a single micro / nanofiber bundle was prepared by twisting a single micro / nanofiber in the Z / S direction.

[0034] (2) The primary structure of several micro / nanofiber bundles obtained in step (1) is prepared by S / Z direction composite twisting to prepare the secondary structure of micro / nanofiber bundles.

[0035] (3) The secondary structures of several micro / nanofiber bundles obtained in step (2) are combined and twisted in the Z / S direction to prepare the tertiary structure of micro / nanofiber bundles.

[0036] (4) The three-level structure of several micro / nanofiber bundles obtained in step (3) is combined and twisted in the S / Z direction to prepare a four-level structure of micro / nanofiber bundles, namely a multi-level composite spiral micro / nanofiber artificial ligament.

[0037] In the fabrication of artificial ligaments composed of 24-40 micron- or nanofibers, the twisting direction of a single micro / nanofiber is Z-twist or S-twist, with a twist of 50 twists / 10cm. The secondary structure of the micro / nanofiber bundle contains 4-6 primary structure fiber bundles, twisted in an S- or Z-twist direction, with a twist of 35 twists / 10cm. The tertiary structure of the micro / nanofiber bundle contains 3 or 4 secondary structure fiber bundles, twisted in a Z- or S-twist direction, with a twist of 30 twists / 10cm. The artificial ligament structure of the micro / nanofiber contains 2 tertiary structure fiber bundles, twisted in an S- or Z-twist direction, with a twist of 17.5 twists / 10cm.

[0038] In the fabrication of artificial ligaments composed of 80-100 micron- or nanofibers, the twisting direction of a single micro / nanofiber is Z-twist or S-twist, with a twist of 50 twists / 10cm. The secondary structure of the micro / nanofiber bundle contains 5-10 primary structure fiber bundles, twisted in an S- or Z-twist direction, with a twist of 35 twists / 10cm. The tertiary structure of the micro / nanofiber bundle contains 2-4 secondary structure fiber bundles, twisted in a Z- or S-twist direction, with a twist of 30 twists / 10cm. The artificial ligament structure of the micro / nanofiber contains 4 or 5 tertiary structure fiber bundles, twisted in an S- or Z-twist direction, with a twist of 12 twists / 10cm.

[0039] The micron and nanofiber yarns used in this invention are made of biodegradable materials such as collagen, chitosan (CS), polylactic acid (PLA), polyglycolic acid (PGA), polyvinyl alcohol (PVA), polyacrylic acid (PAA), polycaprolactone (PCL), polylactide-glycolic acid (PGLA), polydioxanone (PPDO), and other natural or synthetic polymers to achieve their regeneration function.

[0040] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0041] 1. Prepare an artificial ligament composed of 24-40 micron fiber bundles for use as a rotator cuff ligament.

[0042] Example 1:

[0043] A multi-level composite spiral-shaped microfiber artificial ligament is composed of microfibers made of biodegradable materials, which are twisted into fiber bundles through multiple stages, with adjacent twisting stages twisting in opposite directions. Several micro-channels with physical induction properties, composed of fiber bundles, are formed on the surface of the artificial ligament. The artificial ligament consists of 24 microfiber bundles, each with a diameter of 28 μm, formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with four S-twists, tertiary twisting with three Z-twists, and quaternary twisting with two S-twists. The primary twist is 50 twists / 10cm, the secondary twist is 35 twists / 10cm, the tertiary twist is 30 twists / 10cm, and the quaternary twist is 17.5 twists / 10cm. The diameter of the artificial ligament is 1.5 mm.

[0044] The method for preparing this artificial ligament includes the following steps:

[0045] (1) A single microfiber is twisted in the Z direction with a twist of 50 twists / 10cm to prepare a primary structure of a single microfiber bundle;

[0046] (2) Select four micron fiber bundles as primary structures and perform S-direction composite twisting with a twist of 35 twists / 10cm to prepare micron fiber bundle secondary structures.

[0047] (3) Select three micron fiber bundle secondary structures and perform Z-direction composite twisting with a twist of 30 twists / 10cm to prepare micro / nano fiber bundle tertiary structures.

[0048] (4) Select two microfiber bundles with a three-level structure and perform S-direction composite twisting. The twisting degree is 17.5 twists / 10cm. Prepare a microfiber bundle with a four-level structure, namely a multi-level composite spiral type 24-strand microfiber artificial ligament.

[0049] Example 2:

[0050] A multi-level composite spiral-shaped microfiber artificial ligament is composed of microfibers made of biodegradable materials, which are twisted into fiber bundles through multiple stages, with adjacent twisting stages twisting in opposite directions. Several microchannels with physical induction properties, composed of fiber bundles, are formed on the surface of the artificial ligament. The artificial ligament consists of 36 microfiber bundles, each with a diameter of 25 μm, formed through four stages of twisting: a single Z-twist in the primary stage, six S-twists in the secondary stage, three Z-twists in the tertiary stage, and two S-twists in the quaternary stage. The primary twist is 50 twists / 10cm, the secondary twist is 35 twists / 10cm, the tertiary twist is 30 twists / 10cm, and the quaternary twist is 17.5 twists / 10cm. The diameter of the artificial ligament is 2.3 mm.

[0051] The method for preparing this artificial ligament includes the following steps:

[0052] (1) A single microfiber is twisted in the Z direction with a twist of 50 twists / 10cm to prepare a primary structure of a single microfiber bundle;

[0053] (2) Select 6 micron fiber bundles as primary structures and perform S-direction composite twisting with a twist of 35 twists / 10cm to prepare micron fiber bundle secondary structures.

[0054] (3) Select three micron fiber bundle secondary structures and perform Z-direction composite twisting with a twist of 30 twists / 10cm to prepare a micron fiber bundle tertiary structure.

[0055] (4) Select two microfiber bundles with a three-level structure and perform S-direction composite twisting. The twisting degree is 17.5 twists / 10cm. Prepare a microfiber bundle with a four-level structure, namely a multi-level composite spiral type 36-strand microfiber artificial ligament.

[0056] Example 3:

[0057] A multi-level composite spiral-shaped microfiber artificial ligament is composed of microfibers made of biodegradable materials, which are twisted into fiber bundles through multiple stages, with adjacent twisting stages twisting in opposite directions. Several micro-channels with physical induction properties, composed of fiber bundles, are formed on the surface of the artificial ligament. The artificial ligament consists of 40 microfiber bundles, each with a diameter of 22 μm, formed through four stages of twisting: a single Z-twist in the primary stage, five S-twists in the secondary stage, four Z-twists in the tertiary stage, and two S-twists in the quaternary stage. The primary twist is 50 twists / 10cm, the secondary twist is 35 twists / 10cm, the tertiary twist is 30 twists / 10cm, and the quaternary twist is 17.5 twists / 10cm. The diameter of the artificial ligament is 2.5 mm.

[0058] The method for preparing this artificial ligament includes the following steps:

[0059] (1) A single microfiber is twisted in the Z direction with a twist of 50 twists / 10cm to prepare a primary structure of a single microfiber bundle;

[0060] (2) Select 5 micron fiber bundles as primary structures and perform S-direction composite twisting with a twist of 35 twists / 10cm to prepare micron fiber bundle secondary structures.

[0061] (3) Select four micron fiber bundle secondary structures and perform Z-direction composite twisting with a twist of 30 twists / 10cm to prepare micron fiber bundle tertiary structures.

[0062] (4) Select two microfiber bundles with a three-level structure and perform S-direction composite twisting. The twisting degree is 17.5 twists / 10cm to prepare a microfiber bundle with a four-level structure, namely a multi-level composite spiral type 40-strand microfiber artificial ligament.

[0063] II. Preparation of artificial ligaments composed of 24-40 nanofiber bundles for use as rotator cuff ligaments.

[0064] Example 4:

[0065] A multi-level composite spiral nanofiber artificial ligament is formed by multi-level twisting of nanofibers made of biodegradable materials into fiber bundles, with adjacent twisting stages in opposite directions. Several nanochannels with physical induction properties, composed of fiber bundles, are formed on the surface of the artificial ligament. The artificial ligament consists of 24 nanofiber bundles, each with a diameter of 450 nm, formed through four levels of twisting: a single Z-twist in the primary stage, four S-twists in the secondary stage, three Z-twists in the tertiary stage, and two S-twists in the quaternary stage. The primary twist is 50 twists / 10 cm, the secondary twist is 35 twists / 10 cm, the tertiary twist is 30 twists / 10 cm, and the quaternary twist is 17.5 twists / 10 cm. The diameter of the artificial ligament is 1 mm.

[0066] The method for preparing this artificial ligament includes the following steps:

[0067] (1) Twist a single nanofiber in the Z direction with a twist of 50 twists / 10cm to prepare a primary structure of a single nanofiber bundle;

[0068] (2) Four nanofiber bundles were selected as primary structures and S-direction composite twisting was performed. The twisting degree was 35 twists / 10cm to prepare the secondary structure of nanofiber bundles.

[0069] (3) Select three nanofiber bundle secondary structures and perform Z-direction composite twisting with a twist of 30 twists / 10cm to prepare nanofiber bundle tertiary structures.

[0070] (4) Select two nanofiber bundles with a three-level structure and perform S-direction composite twisting with a twist of 17.5 twists / 10cm to prepare a nanofiber bundle with a four-level structure, namely a multi-level composite spiral type 24-strand nanofiber artificial ligament.

[0071] Example 5:

[0072] A multi-level composite spiral nanofiber artificial ligament is composed of nanofibers made of biodegradable materials, which are twisted into fiber bundles through multiple stages, with adjacent twisting stages twisting in opposite directions. Several nanochannels with physical induction properties, composed of fiber bundles, are formed on the surface of the artificial ligament. The artificial ligament consists of 36 nanofiber bundles, each with a diameter of 400 nm, formed through four stages of twisting: a single Z-twist in the primary stage, six S-twists in the secondary stage, three Z-twists in the tertiary stage, and two S-twists in the quaternary stage. The primary twist is 50 twists / 10 cm, the secondary twist is 35 twists / 10 cm, the tertiary twist is 30 twists / 10 cm, and the quaternary twist is 17.5 twists / 10 cm. The diameter of the artificial ligament is 1.5 mm.

[0073] The method for preparing this artificial ligament includes the following steps:

[0074] (1) Twist a single nanofiber in the Z direction with a twist of 50 twists / 10cm to prepare a primary structure of a single nanofiber bundle;

[0075] (2) Six nanofiber bundles were selected as primary structures and S-direction composite twisting was performed. The twisting degree was 35 twists / 10cm to prepare the secondary structure of nanofiber bundles.

[0076] (3) Select three nanofiber bundle secondary structures and perform Z-direction composite twisting with a twist of 30 twists / 10cm to prepare nanofiber bundle tertiary structures.

[0077] (4) Select two nanofiber bundles with a three-level structure and perform S-direction composite twisting. The twisting degree is 17.5 twists / 10cm to prepare a nanofiber bundle with a four-level structure, namely a multi-level composite spiral type 36-strand nanofiber artificial ligament.

[0078] Example 6:

[0079] A multi-level composite spiral nanofiber artificial ligament is composed of nanofibers made of biodegradable materials, which are twisted into fiber bundles through multiple stages, with adjacent twisting stages twisting in opposite directions. Several nanochannels with physical induction properties, composed of fiber bundles, are formed on the surface of the artificial ligament. The artificial ligament consists of 40 nanofiber bundles, each with a diameter of 350 nm, formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with five S-twists, tertiary twisting with four Z-twists, and quaternary twisting with two S-twists. The primary twist is 50 twists / 10 cm, the secondary twist is 35 twists / 10 cm, the tertiary twist is 30 twists / 10 cm, and the quaternary twist is 17.5 twists / 10 cm. The diameter of the artificial ligament is 2 mm.

[0080] The method for preparing this artificial ligament includes the following steps:

[0081] (1) Twist a single nanofiber in the Z direction with a twist of 50 twists / 10cm to prepare a primary structure of a single nanofiber bundle;

[0082] (2) Select five nanofiber bundles as primary structures and perform S-direction composite twisting with a twist of 35 twists / 10cm to prepare nanofiber bundle secondary structures.

[0083] (3) Four nanofiber bundle secondary structures were selected and Z-direction composite twisting was performed. The twisting degree was 30 twists / 10cm to prepare the nanofiber bundle tertiary structure.

[0084] (4) Select two nanofiber bundles with a three-level structure and perform S-direction composite twisting. The twisting degree is 17.5 twists / 10cm to prepare a nanofiber bundle with a four-level structure, namely a multi-level composite spiral type 40-strand nanofiber artificial ligament.

[0085] III. Prepare artificial ligaments composed of 80-100 micron fiber bundles for use as anterior cruciate ligaments of the knee joint.

[0086] Example 7:

[0087] A multi-level composite spiral-shaped microfiber artificial ligament is composed of microfibers made of biodegradable materials, which are twisted into fiber bundles through multiple stages, with adjacent twisting stages twisting in opposite directions. Several micro-channels with physical induction properties, composed of fiber bundles, are formed on the surface of the artificial ligament. The artificial ligament consists of 80 microfiber bundles, each with a diameter of 52 μm, formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with 5 S-twists, tertiary twisting with 4 Z-twists, and quaternary twisting with 4 S-twists. The primary twist is 50 twists / 10 cm, the secondary twist is 35 twists / 10 cm, the tertiary twist is 30 twists / 10 cm, and the quaternary twist is 12 twists / 10 cm. The diameter of the artificial ligament is 4.5 mm.

[0088] The method for preparing this artificial ligament includes the following steps:

[0089] (1) A single microfiber is twisted in the Z direction with a twist of 50 twists / 10cm to prepare a primary structure of a single microfiber bundle;

[0090] (2) Select 5 micron fiber bundles as primary structures and perform S-direction composite twisting with a twist of 35 twists / 10cm to prepare micron fiber bundle secondary structures.

[0091] (3) Select four micron fiber bundle secondary structures and perform Z-direction composite twisting with a twist of 30 twists / 10cm to prepare micro / nano fiber bundle tertiary structures.

[0092] (4) Four microfiber bundles were selected for the third-level structure and S-direction composite twisting was performed. The twisting degree was 12 twists / 10cm. The microfiber bundles were then prepared into a fourth-level structure, namely a multi-level composite spiral type 80-strand microfiber artificial ligament.

[0093] Example 8:

[0094] A multi-level composite spiral-shaped microfiber artificial ligament is composed of microfibers made of biodegradable materials, which are twisted into fiber bundles through multiple stages, with adjacent twisting stages twisting in opposite directions. Several micro-channels with physical induction properties, composed of fiber bundles, are formed on the surface of the artificial ligament. The artificial ligament consists of 90 microfiber bundles, each with a diameter of 45 μm, formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with 6 S-twists, tertiary twisting with 3 Z-twists, and quaternary twisting with 5 S-twists. The primary twist is 50 twists / 10 cm, the secondary twist is 35 twists / 10 cm, the tertiary twist is 30 twists / 10 cm, and the quaternary twist is 12 twists / 10 cm. The diameter of the artificial ligament is 5 mm.

[0095] The method for preparing this artificial ligament includes the following steps:

[0096] (1) A single microfiber is twisted in the Z direction with a twist of 50 twists / 10cm to prepare a primary structure of a single microfiber bundle;

[0097] (2) Select 6 micron fiber bundles as primary structures and perform S-direction composite twisting with a twist of 35 twists / 10cm to prepare micron fiber bundle secondary structures.

[0098] (3) Select three micron fiber bundle secondary structures and perform Z-direction composite twisting with a twist of 30 twists / 10cm to prepare micro / nano fiber bundle tertiary structures.

[0099] (4) Five microfiber bundles were selected for three-level structure and S-direction composite twisting was performed. The twisting degree was 12 twists / 10cm. A four-level structure of microfiber bundles was prepared, namely a multi-level composite spiral type 90-strand microfiber artificial ligament.

[0100] Example 9:

[0101] A multi-level composite spiral-shaped microfiber artificial ligament is composed of microfibers made of biodegradable materials, which are twisted into fiber bundles through multiple stages, with adjacent twisting stages twisting in opposite directions. Several micro-channels with physical induction properties, composed of fiber bundles, are formed on the surface of the artificial ligament. The artificial ligament consists of 100 microfiber bundles, each with a diameter of 43 μm, formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with 10 S-twists, tertiary twisting with 2 Z-twists, and quaternary twisting with 5 S-twists. The primary twist is 50 twists / 10 cm, the secondary twist is 35 twists / 10 cm, the tertiary twist is 30 twists / 10 cm, and the quaternary twist is 12 twists / 10 cm. The diameter of the artificial ligament is 5.5 mm.

[0102] The method for preparing this artificial ligament includes the following steps:

[0103] (1) A single microfiber is twisted in the Z direction with a twist of 50 twists / 10cm to prepare a primary structure of a single microfiber bundle;

[0104] (2) Select 10 micron fiber bundles as primary structures and perform S-direction composite twisting with a twist of 35 twists / 10cm to prepare micron fiber bundle secondary structures.

[0105] (3) Select two micron fiber bundle secondary structures and perform Z-direction composite twisting with a twist of 30 twists / 10cm to prepare micro / nano fiber bundle tertiary structures.

[0106] (4) Select 5 microfiber bundles of three-level structure and perform S-direction composite twisting. The twisting degree is 12 twists / 10cm to prepare microfiber bundle of four-level structure, namely multi-level composite spiral type 100-strand microfiber artificial ligament.

[0107] IV. Prepare an artificial ligament composed of 80-100 nanofiber bundles for use as an anterior cruciate ligament of the knee joint.

[0108] Example 10:

[0109] A multi-level composite spiral nanofiber artificial ligament is composed of nanofibers made of biodegradable materials, which are twisted into fiber bundles through multiple stages, with adjacent twisting stages twisting in opposite directions. Several nanochannels with physical induction properties, composed of fiber bundles, are formed on the surface of the artificial ligament. The artificial ligament consists of 80 nanofiber bundles, each with a diameter of 780 nm, formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with 5 S-twists, tertiary twisting with 4 Z-twists, and quaternary twisting with 4 S-twists. The primary twist is 50 twists / 10 cm, the secondary twist is 35 twists / 10 cm, the tertiary twist is 30 twists / 10 cm, and the quaternary twist is 12 twists / 10 cm. The diameter of the artificial ligament is 4 mm.

[0110] The method for preparing this artificial ligament includes the following steps:

[0111] (1) Twist a single nanofiber in the Z direction with a twist of 50 twists / 10cm to prepare a primary structure of a single nanofiber bundle;

[0112] (2) Select five nanofiber bundles as primary structures and perform S-direction composite twisting with a twist of 35 twists / 10cm to prepare nanofiber bundle secondary structures.

[0113] (3) Four nanofiber bundle secondary structures were selected and Z-direction composite twisting was performed. The twisting degree was 30 twists / 10cm to prepare the nanofiber bundle tertiary structure.

[0114] (4) Four nanofiber bundles were selected for the third-level structure and composite twisted in the S direction. The twisting degree was 12 twists / 10cm. The nanofiber bundles were then prepared into a fourth-level structure, namely a multi-level composite spiral type 80-strand nanofiber artificial ligament.

[0115] Example 11:

[0116] A multi-level composite spiral nanofiber artificial ligament is composed of nanofibers made of biodegradable materials, which are twisted into fiber bundles through multiple stages, with adjacent twisting stages twisting in opposite directions. Several nanochannels with physical induction properties, composed of fiber bundles, are formed on the surface of the artificial ligament. The artificial ligament consists of 90 nanofiber bundles, each with a diameter of 750 nm, formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with 6 S-twists, tertiary twisting with 3 Z-twists, and quaternary twisting with 5 S-twists. The primary twist is 50 twists / 10 cm, the secondary twist is 35 twists / 10 cm, the tertiary twist is 30 twists / 10 cm, and the quaternary twist is 12 twists / 10 cm. The diameter of the artificial ligament is 4.5 mm.

[0117] The method for preparing this artificial ligament includes the following steps:

[0118] (1) Twist a single nanofiber in the Z direction with a twist of 50 twists / 10cm to prepare a primary structure of a single nanofiber bundle;

[0119] (2) Six nanofiber bundles were selected as primary structures and S-direction composite twisting was performed. The twisting degree was 35 twists / 10cm to prepare the secondary structure of nanofiber bundles.

[0120] (3) Select three nanofiber bundle secondary structures and perform Z-direction composite twisting with a twist of 30 twists / 10cm to prepare nanofiber bundle tertiary structures.

[0121] (4) Five nanofiber bundles were selected for the third-level structure and composite twisted in the S direction. The twisting degree was 12 twists / 10cm. The nanofiber bundles were then prepared into a fourth-level structure, namely a multi-level composite spiral type 90-strand nanofiber artificial ligament.

[0122] Example 12:

[0123] A multi-level composite spiral nanofiber artificial ligament is formed by multi-level twisting of nanofibers made of biodegradable materials into fiber bundles, with adjacent twisting stages twisting in opposite directions. Several nanochannels with physical induction properties, composed of fiber bundles, are formed on the surface of the artificial ligament. The artificial ligament consists of 100 nanofiber bundles, each with a diameter of 720 nm, formed through four levels of twisting: primary twisting with a single Z-twist, secondary twisting with 10 S-twists, tertiary twisting with 2 Z-twists, and quaternary twisting with 5 S-twists. The primary twist is 50 twists / 10 cm, the secondary twist is 35 twists / 10 cm, the tertiary twist is 30 twists / 10 cm, and the quaternary twist is 12 twists / 10 cm. The diameter of the artificial ligament is 5 mm.

[0124] The method for preparing this artificial ligament includes the following steps:

[0125] (1) Twist a single nanofiber in the Z direction with a twist of 50 twists / 10cm to prepare a primary structure of a single nanofiber bundle;

[0126] (2) Ten nanofiber bundles were selected as primary structures and S-direction composite twisting was performed. The twisting degree was 35 twists / 10cm to prepare the secondary structure of nanofiber bundles.

[0127] (3) Select two nanofiber bundle secondary structures and perform Z-direction composite twisting with a twist of 30 twists / 10cm to prepare nanofiber bundle tertiary structures.

[0128] (4) Five nanofiber bundles were selected for the third-level structure and composite twisted in the S direction. The twisting degree was 12 twists / 10cm. The nanofiber bundles were then prepared into a fourth-level structure, namely a multi-level composite spiral type 100-strand nanofiber artificial ligament.

[0129] The performance test results of the multi-level composite spiral micro / nanofiber artificial ligament prepared according to this embodiment of the invention are as follows:

[0130] like Figure 5 As shown, the diameters of 50 yarns were randomly calculated, resulting in the following diameters: primary structure of multi-level composite spiral micro / nanofiber yarn bundle: 171.40±2.39μm; secondary structure: 555.53±12.88μm; tertiary structure: 969.78±27.99μm; and artificial ligament structure: 1610.45±36.36μm.

[0131] from Figure 4 , 6 As shown in the SEM images in Figure 7, the artificial ligament produced by the multi-strand Z / S twist alternating weaving method has the following characteristics: the yarns are of uniform thickness and neatly arranged, and there is no significant difference in the deflection angle of each twist direction, which can ensure that the yarn strength remains consistent when the artificial ligament structure breaks; the yarn cohesion is strong, and the combination of opposite twist directions can disperse its tension, allowing for flexible bending angles, resulting in a tight and uniform spatial structure and good tensile strength; in addition, as can be seen from the figures, through the alternating Z / S twist, the yarn orientation gradually increases with the twisting process. This weaving method can significantly improve the maximum breaking load strength and provide a certain mechanical strength during the early tissue healing process, thus meeting the mechanical requirements of artificial ligament regeneration and reconstruction.

[0132] Figure 8 The mechanical properties of 36-strand nanofiber yarn and 36-strand microfiber yarn spirally twisted are shown. The maximum load is 128.43 N, the Young's modulus is 487.85 ± 16.75 MPa, and the elongation at break is 30%-45%. Figure 9The mechanical properties of helically twisted 90-strand nanofiber yarn and 90-strand microfiber yarn are shown in the diagrams. The maximum load is 283.72 N, and the elongation at break is significantly improved. The mechanical property characterization diagrams clearly show that the diameter of the artificial ligament structure increases progressively with the increase of twisted yarn, and the breaking stress of the nanofiber yarn is significantly higher than that of the microfiber yarn. With the increase of strands, the load and elongation at break of the yarn increase accordingly. Under the premise that the anterior cruciate ligament bears the greatest stress when the knee joint of a healthy adult male is subjected to a posterior femoral load of 134 N and flexion is 30°, the preparation method provided by this invention produces an artificial ligament with mechanical properties close to and potentially exceeding those of an autologous anterior cruciate ligament, thus meeting the mechanical requirements of artificial ligament scaffolds. This weaving method, which involves multi-layered reverse twisting, alternating twisting directions (Z / S twist) between adjacent layers, and controllable twist and twist direction, effectively avoids the excessive tilting problem caused by single-direction fiber twisting. While improving mechanical properties, it creates micron and nanochannels with physical induction properties on the surface of the artificial ligament, giving it a tight and stable internal anisotropic spatial structure. Furthermore, the number of fiber bundles and the twist of the multi-strand yarns can be arbitrarily adjusted to meet the structural stability and flexibility requirements of the artificial ligament scaffold.

[0133] The anterior cruciate ligament (ACL) is one of the most important ligaments in the knee joint. It is composed of dense collagen fibers that bear tensile forces during knee flexion, extension, and rotation. The ACL's main function is to limit excessive anterior displacement of the tibia relative to the femur, while also providing stability during knee rotation and deceleration. Therefore, its biomechanical properties are crucial for knee joint function. When testing the mechanical properties of the ACL, researchers typically use tensile tests to determine parameters such as its elastic modulus, breaking strength, and elongation at break. The artificial ligament product obtained by the preparation method used in this invention exhibits good mechanical properties; with the increase in the number of strands, the load and elongation at break of the yarn increase accordingly. The mechanical property characterization diagram shows that, under the premise that the ACL bears the greatest stress at 30° flexion when the knee joint of a healthy adult male is subjected to a posterior femoral load of 134N, the following parameters are also considered: Figure 7 , 8 As shown, the 36-strand and 90-strand nanofiber artificial ligaments obtained in Embodiments 5 and 11 of this utility model have a maximum load of 283.72 N, a Young's modulus of 487.85 ± 16.75 MPa, and a breakage elongation of 40%-95%. Their mechanical properties are close to and may even surpass those of autologous anterior cruciate ligaments. They have a tight and stable spatial biomimetic structure that meets the complex anterior and posterior mechanical requirements and rotational stability of the knee joint.

[0134] The rotator cuff ligaments connect the acromioclavicular joint (between the scapula and clavicle) and the sternoclavicular joint (between the scapula and sternum). Among them, the coracoacromial ligament is one of the few strong triangular ligaments in the human body that connects the coracoid process of the scapula to the acromion, forming the so-called "coracoacromial arch." The main function of the coracoacromial ligament is to limit medial and superior dislocation of the humeral head. It acts as a barrier in the upper part of the shoulder joint, separating the subacromial bursa from the acromioclavicular joint. The coracoacromial ligament plays a crucial role in the stability of the shoulder joint, especially in cases of rotator cuff muscle tears. According to research, the coracoacromial ligament has an outer length of approximately 3.2 cm, a middle thickness of approximately 2 mm, and a tensile range generally between 127.8-200 N. Furthermore, the anatomy of the coracoacromial ligament is related to acromioplasty techniques, with fibrous bundles continuously attaching side-by-side around the acromion. Therefore, the coracoacromial ligament needs to possess high flexibility and a certain tensile strength. The artificial ligament product obtained by the preparation method of this utility model has the flexibility to rotate at any angle, and the diameter and thickness can be controlled. The fracture load reaches 300N, and it has a large number of nano- and micro-sized oriented channels similar to the structure of autologous ligaments. By selecting appropriate fiber diameter and twisting level, it can meet the mechanical requirements of the rotator cuff joint and fully satisfy the complex rotational stability function of the rotator cuff joint.

[0135] The inguinal ligament is a band of connective tissue that extends from the anterior superior iliac spine to the pubic tubercle, located at the junction of the abdomen and thigh. It primarily connects the pubis and hip bones and is an important structure in the groin region. The inguinal ligament is a relatively thick tissue, approximately 2-3.5 mm in diameter. The diameter of a single fiber bundle is normally about 10-40 μm, varying depending on individual differences and measurement methods. The inguinal ligament primarily performs the following functions:

[0136] ① Support function: The inguinal ligament provides support for the groin area by connecting the abdomen and thigh, keeping the abdominal organs in the correct position.

[0137] ② Limits range of motion: It restricts movement between the groin and pelvis, preventing overstretching and instability, and maintaining joint stability.

[0138] ③ Traction function: During walking and running, the inguinal ligament plays a traction role during muscle contraction, helping to maintain the coordination and efficiency of movement.

[0139] ④ Protective function: It helps protect the blood vessels and nerves in the groin area from mechanical damage.

[0140] Therefore, the inguinal ligament possesses high mechanical properties and must be strong enough to withstand the pressure of abdominal contents on the abdominal wall, especially during strenuous activity or lifting heavy objects. Its strength primarily depends on factors such as the ligament's thickness, shape, and tensile strength. The artificial ligament product prepared by this invention allows for flexible adjustment of the fiber strand count to achieve the required diameter range for the inguinal ligament. After twisting, the product exhibits a breaking elongation of 40%-95%, a Young's modulus of 50-500 MPa, and a compact internal spatial structure, thus meeting the requirements of the artificial inguinal ligament for maintaining the movement and stability of the lower limbs and abdomen. It is evident that this invention, by selecting appropriate fiber diameters and twist levels, can meet the structural, dimensional, and mechanical performance requirements for inguinal ligaments.

[0141] In summary, this invention is based on biodegradable micro / nanofibers, prepared by twisting single micron or nanofiber bundles and then performing multi-layered reverse-direction composite twisting. The resulting artificial ligament structure is an anisotropic hierarchical structure, where the number and twist of micro / nanofiber bundles in each layer can be arbitrarily adjusted. The twisting direction (Z / S twist) of adjacent layers alternates, effectively avoiding the excessive tilting caused by single-direction fiber twisting, which leads to a decrease in strength. This allows for flexible control of the diameter, structure, and mechanical properties of the artificial ligament, ensuring close connection and structural stability between layers. Therefore, it possesses good mechanical properties and slow degradation, without causing a decrease in the mechanical properties of the tissue-engineered ligament during degradation. The multi-level helical structure ensures that the ligament simultaneously maintains the anterior-posterior and complex rotational stability of the knee joint, shoulder joint, and other joints and tissues. Furthermore, the micron and nanochannels with physical induction properties formed on the surface of the artificial ligament facilitate cell overgrowth and better promote ligament regeneration, achieving a biomimetic effect of the artificial ligament scaffold and realizing the goal of promoting autologous healing between the graft and host. By using twisting technology, a material with good biocompatibility, excellent mechanical properties, a robust and reliable macroscopic structure, and a microscopic structure with biomimetic effects can be obtained. Furthermore, the preparation method is simple and controllable, and the cost is effectively controlled. Therefore, it has broad prospects for medical applications and high industrialization value.

[0142] Of course, the above description is not intended to limit the present utility model, nor is the present utility model limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present utility model should be protected by the present utility model.

Claims

1. A multi-level composite spiral-shaped micro / nanofiber artificial ligament, characterized in that: The artificial ligament is composed of micron- or nano-sized fibers made of biodegradable materials, which are twisted into fiber bundles through multiple stages. The twisting stages are twisted in opposite directions, forming several micron- and nano-channels with physical induction properties composed of fiber bundles on the surface of the artificial ligament. The diameter of a single fiber bundle is 350nm-52μm, and the diameter of the artificial ligament is 1-5.5mm.

2. The multi-level composite spiral micro / nanofiber artificial ligament according to claim 1, characterized in that: The artificial ligament is made of micron-sized fibers of biodegradable material through multi-stage twisting. The number of micron-sized fiber bundles that make up the artificial ligament is 24-100, of which the diameter of a single micron-sized fiber bundle is 22-52μm, and the diameter of the artificial ligament is 1.5-5.5mm.

3. The multi-level composite spiral micro / nanofiber artificial ligament according to claim 2, characterized in that: The artificial ligament consists of 24-40 micron-sized fiber bundles, each with a diameter of 22-28 μm. These bundles are formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with 4-6 S-twists, tertiary twisting with 3 or 4 Z-twists, and quaternary twisting with 2 S-twists. The primary twisting has a twist rate of 50 twists / 10cm, the secondary twisting has a twist rate of 35 twists / 10cm, the tertiary twisting has a twist rate of 30 twists / 10cm, and the quaternary twisting has a twist rate of 17.5 twists / 10cm. The diameter of the artificial ligament is 1.5-2.5 mm.

4. The multi-level composite spiral micro / nanofiber artificial ligament according to claim 2, characterized in that: The artificial ligament consists of 80-100 micron-sized fiber bundles, each with a diameter of 43-52 μm. These bundles are formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with 5-10 S-twists, tertiary twisting with 2-4 Z-twists, and quaternary twisting with 4 or 5 S-twists. The primary twisting has a twist rate of 50 twists / 10cm, the secondary twisting has a twist rate of 35 twists / 10cm, the tertiary twisting has a twist rate of 30 twists / 10cm, and the quaternary twisting has a twist rate of 12 twists / 10cm. The diameter of the artificial ligament is 4.5-5.5 mm.

5. The multi-level composite spiral micro / nanofiber artificial ligament according to claim 1, characterized in that: The artificial ligament is made of nanofibers of biodegradable material through multi-stage twisting. The number of nanofiber bundles that make up the artificial ligament is 24-100, with the diameter of a single nanofiber bundle being 350-780nm and the diameter of the artificial ligament being 1-5mm.

6. The multi-level composite spiral micro / nanofiber artificial ligament according to claim 5, characterized in that: The artificial ligament consists of 24-40 nanofiber bundles, each with a diameter of 350-450 nm. These bundles are formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with 4-6 S-twists, tertiary twisting with 3 or 4 Z-twists, and quaternary twisting with 2 S-twists. The primary twist has a twist rate of 50 twists / 10 cm, the secondary twist has a twist rate of 35 twists / 10 cm, the tertiary twist has a twist rate of 30 twists / 10 cm, and the quaternary twist has a twist rate of 17.5 twists / 10 cm. The diameter of the artificial ligament is 1-2 mm.

7. The multi-level composite spiral micro / nanofiber artificial ligament according to claim 5, characterized in that: The artificial ligament consists of 80-100 nanofiber bundles, each with a diameter of 720-780 nm. These bundles are formed through four stages of twisting: primary twisting with a single Z-twist, secondary twisting with 5-10 S-twists, tertiary twisting with 2-4 Z-twists, and quaternary twisting with 4 or 5 S-twists. The primary twist has a twist rate of 50 twists / 10cm, the secondary twist has a twist rate of 35 twists / 10cm, the tertiary twist has a twist rate of 30 twists / 10cm, and the quaternary twist has a twist rate of 12 twists / 10cm. The diameter of the artificial ligament is 4-5 mm.

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