Artificial cervical intervertebral disc based on biological bionic structure

Abstract

The invention relates to the technical field of artificial prostheses, and discloses an artificial cervical intervertebral disc based on a biological bionic structure, which comprises an upper end plate, a lower end plate and an elastomer core arranged between the upper end plate and the lower end plate, the elastomer core comprises a front annulus fibrosus, a nucleus pulposus and a rear annulus fibrosus; the front fiber ring is composed of an outer side fiber layer, a middle transition layer, an inner side fiber layer and front collagenous fibers located among the fiber layers. The artificial cervical intervertebral disc can be more naturally matched with the physiological movement mode of vertebrae after being implanted by adopting differentiated arrangement of front and rear fibrous rings, gradient dip angle design of collagenous fibers, elastic deformation characteristics of nucleus pulposus and material combination with different elastic moduli; the irregular-shaped end plate is more attached to the cervical vertebra hook process joint and adapts to multi-direction complex movement.

Description

Technical Field

[0001] This invention relates to the field of artificial prosthesis technology, and in particular to an artificial cervical intervertebral disc based on a biomimetic structure. Background Technology

[0002] With the accelerating aging of society and the increasing proportion of people working at desks for long periods, the incidence of cervical spondylosis is showing a year-on-year upward trend. Artificial cervical disc replacement surgery can relieve nerve compression while preserving the physiological motor function of the cervical spine, helping to maintain normal mobility and stability of adjacent segments, reducing pressure on adjacent segments, lowering the incidence of new lesions in adjacent segments, and enabling patients to return to a normal life earlier after surgery. However, currently, the artificial cervical disc prostheses used clinically in China mainly rely on imports, and the materials are mostly metal, which are prone to artifacts in postoperative imaging examinations (especially MR imaging), thus affecting imaging evaluation. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by proposing an artificial cervical intervertebral disc based on a biomimetic structure.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: An artificial cervical intervertebral disc based on a biomimetic structure includes a superior endplate, a inferior endplate, and an elastic core disposed between the superior and inferior endplates. The elastic core includes an anterior annulus fibrosus, a nucleus pulposus, and a posterior annulus fibrosus. The anterior annulus fibrosus is composed of an outer fibrous layer, a middle transition layer, and an inner fibrous layer, as well as anterior collagen fibers located between the fibrous layers. The posterior annulus fibrosus is composed of a posterior fibrous layer and equidistant posterior collagen fibers arranged perpendicularly and parallel to each other between the fibrous layers. The nucleus pulposus is elliptical and occupies 50%-60% of the top-view area of ​​the elastic core. Both the superior and inferior endplates are arc-shaped structures with both ends curving outwards and upwards, with both ends extending upwards to form pointed tips. The superior and inferior endplates are in contact with the surface of the elastic core. The upper endplate has an upper endplate fixing tooth on the side away from the elastomer core, and the lower endplate has a lower endplate fixing tooth on the side away from the elastomer core.

[0005] Preferably, the rear fiber ring is a ring-shaped structure with uniform thickness.

[0006] Preferably, the anterior annulus fibrosus has an arc-shaped structure, with the thickness in the middle of the anterior annulus fibrosus being greater than the thickness at both ends, and both the anterior and posterior annulus fibrosus surround and enclose the nucleus pulposus.

[0007] Preferably, the procollagen fibers include: procollagen I fibers, procollagen II fibers, and procollagen III fibers, which are distributed sequentially along the thickness direction of the anterior limiting ring and intertwine with each other in the midline region to form a fiber cross-linking structure.

[0008] Preferably, the procollagen fibers and posterior collagen fibers are cylindrical.

[0009] Preferably, the pre-III collagen fibers disposed in the outer fiber layer branch downward and outward from the upper end at the midline, and the distribution pattern of the pre-III collagen fibers spreading outward towards the outer side makes the angle between the pre-III collagen fibers and the surface of the outer fiber layer gradually increase from the midline to both sides, and the two sides are symmetrically distributed. The tilt angle range is 0°-65°, with the tilt angle at the centerline being 0° and the tilt angle at the outermost edge being 65°.

[0010] Preferably, the pre-II collagen fibers are located between the outer fiber layer and the intermediate transition layer, and the pre-I collagen fibers are located between the intermediate transition layer and the inner fiber layer. The two ends of the pre-II and pre-I collagen fibers extend upward from the lower outer end and towards the middle, gradually converging along the midline and intertwining in the middle region. The inclination angle between the pre-II collagen fibers and the surface of the intermediate transition layer, and the inclination angle between the pre-I collagen fibers and the surface of the inner fiber layer, both gradually decrease from the outermost edge to the middle and are symmetrically distributed on both sides. The inclination angle ranges from 45° to 65°, with the inclination angle near the midline being 45° and the inclination angle at the outermost edge being 65°.

[0011] Preferably, the upper endplate, lower endplate, upper endplate fixing teeth, and lower endplate fixing teeth are all graphene nanosheet-reinforced conductive polyetheretherketone composite materials; the front fiber ring and the rear fiber ring are polyurethane polymer materials with different elastic moduli; and the core is a thermoplastic polyurethane rubber material.

[0012] Preferably, the upper surface of the upper endplate, the lower surface of the lower endplate, the surface of the upper endplate fixing teeth, and the surface of the lower endplate fixing teeth are all coated with a composite antibacterial coating containing 0.5 wt% silver ions and hydroxyapatite by plasma spraying.

[0013] The beneficial effects of this invention are as follows: 1. This invention, by mimicking the tissue structure and configuration of a biological intervertebral disc, enables the artificial cervical intervertebral disc to coordinate with the natural movement of the vertebrae during movements such as flexion, extension, lateral bending, axial rotation, and translation, thereby improving overall movement matching. It can reproduce the structure and material properties of the human cervical intervertebral disc, allowing the artificial cervical intervertebral disc to more naturally match the physiological movement of the vertebrae after implantation.

[0014] 2. This invention replicates the overall structure of the cervical intervertebral disc. Its frontal structure has an upward extension at both ends (similar to the corresponding relationship of the shape in the natural cervical spine structure). The overall irregular shape design is more in line with the physiological shape of the upper and lower endplates of the cervical spine, making the arrangement of the anterior and posterior annulus fibrosus and fibrous tissue more suitable for the movement of the uncinate process joint of the cervical spine. It can realize physiological activities such as flexion and extension, lateral bending, axial rotation and translation of the cervical spine. The overall shape is more in line with the anatomical shape of the uncinate process joint of the cervical spine, which is conducive to realizing multi-directional movement.

[0015] 3. In this invention, the anterior collagen fibers at different locations are set with differentiated inclination angles, while the posterior collagen fibers are arranged vertically and interwoven in the central region, creating a gradient distribution of the fibrous annulus from the outside in. This structure facilitates the elastic deformation of the nucleus pulposus and allows for the adjustment of the mechanical properties of different regions of the artificial cervical intervertebral disc, thereby achieving anisotropy in its internal distribution, improving the physiological motion matching degree after implantation, and contributing to the zonal regulation of the intervertebral disc's mechanical properties.

[0016] 4. The structural differences and symmetrical layout of the annulus fibrosus before and after the present invention enable the nucleus pulposus to undergo favorable elastic deformation under stress; different levels of collagen fibers and fibrous layers exhibit different tensile responses under stress, thereby simulating the dispersion and buffering of external pressure within the natural intervertebral disc.

[0017] 5. The anterior annulus fibrosus, posterior annulus fibrosus, and nucleus pulposus are made of polyurethane and rubber materials with different elastic moduli, giving the overall structure good elasticity and energy absorption properties, which helps to resist the impact of cervical spine movement and improve post-implantation stability.

[0018] 6. Both the upper and lower endplates are made of graphene-reinforced polyetheretherketone (PEEK) materials, and are coated with an antibacterial composite coating containing silver ions and hydroxyapatite. This coating balances antibacterial and bone integration properties, helps reduce artifacts in CT scans, improves the accuracy of imaging diagnosis, and makes postoperative image assessment clearer. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of an artificial cervical intervertebral disc based on a biomimetic structure proposed in an embodiment of the present invention; Figure 2 This is a top view of the overall structure of an artificial cervical intervertebral disc based on a biomimetic structure proposed in an embodiment of the present invention; Figure 3 This is a top view of the elastomeric core in an artificial cervical intervertebral disc based on a biomimetic structure, as proposed in an embodiment of the present invention. Figure 4 This is a schematic diagram of the medial fibrous layer 203-1 and anterior I collagen fiber 203-4I in an artificial cervical intervertebral disc based on a biomimetic structure proposed in an embodiment of the present invention. Figure 5 This is a schematic diagram of the intermediate transition layer 203-2 and the anterior II collagen fiber 203-4Ⅱ in an artificial cervical intervertebral disc based on a biomimetic structure proposed in an embodiment of the present invention; Figure 6 This is a schematic diagram of the lateral fibrous layer 203-3 and the anterior III collagen fiber 203-4Ⅲ in an artificial cervical intervertebral disc based on a biomimetic structure proposed in an embodiment of the present invention; Figure 7 This is a schematic diagram of the posterior fibrous annulus fibrosus of an artificial cervical intervertebral disc based on a biomimetic structure, as proposed in an embodiment of the present invention.

[0020] In the diagram: 101-Upper endplate fixing tooth; 1-Upper endplate; 2-Elastomer core; 3-Lower endplate; 301-Lower endplate fixing tooth; 201-Posterior annulus fibrosus; 201-1-Posterior fibrous layer; 201-2-Posterior collagen fiber; 202-Nucleus pulposus; 203-Anterior annulus fibrosus; 203-1-Medial fibrous layer; 203-2-Intermediate transition layer; 203-3-External fibrous layer; 203-4-Anterior collagen fiber; 203-4Ⅰ-Anterior I collagen fiber; 203-4Ⅱ-Anterior II collagen fiber; 203-4Ⅲ-Anterior III collagen fiber. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] In one embodiment, refer to Figures 1 to 7 An artificial cervical intervertebral disc based on a biomimetic structure includes a superior endplate 1, a inferior endplate 3, and an elastic core 2 disposed between the superior endplate 1 and the inferior endplate 3. The elastic core 2 includes an anterior annulus fibrosus 203, a nucleus pulposus 202, and a posterior annulus fibrosus 201. The anterior annulus fibrosus 203 is composed of an outer fibrous layer 203-3, an intermediate transition layer 203-2, and an inner fibrous layer 203-1, as well as anterior collagen fibers 203-4 located between the fibrous layers. The posterior annulus fibrosus 201 is composed of a posterior fibrous layer 201-1 and an anterior collagen fiber 203-4 located between the fibrous layers along the thickness of the fibrous layer. It consists of equidistantly arranged post-collagen fibers 201-2 arranged perpendicularly and parallel to each other; the nucleus pulposus 202 is elliptical and accounts for 50%-60% of the top view area of ​​the elastomer core 2; the front view of the upper endplate 1 and the lower endplate 3 are both arc-shaped structures with both ends curving outward and upward. Both ends of the upper endplate 1 and the lower endplate 3 extend upward to form a tip. The curvature of the upper endplate 1 is the same as the curvature of the lower surface of the adjacent upper cone, and the curvature of the lower endplate 3 is the same as the curvature of the upper surface of the adjacent lower cone. The upper endplate 1 and the lower endplate 3 are in contact with the surface of the elastomer core 2. The upper endplate 1 has an upper endplate fixing tooth 101 on the side away from the elastic core 2, and the lower endplate 3 has a lower endplate fixing tooth 301 on the side away from the elastic core 2. The upper endplate 1 and the lower endplate 3 are fixed to the vertebral body by the upper endplate fixing tooth 101 and the lower endplate fixing tooth 301 to prevent displacement. The contact surfaces of the upper surface of the upper endplate 1 and the lower surface of the lower endplate 3 with the vertebral body are stably connected to achieve axial force transmission.

[0023] In a preferred embodiment of the present invention, the rear fiber ring 201 is a ring-shaped structure with uniform thickness.

[0024] In a preferred embodiment of the present invention, the anterior annulus fibrosus 203 has an arc-shaped structure, the thickness of the middle part of the anterior annulus fibrosus 203 is greater than the thickness of the two ends, and both the anterior annulus fibrosus 203 and the posterior annulus fibrosus 201 surround and wrap around the nucleus pulposus 202.

[0025] In a preferred embodiment of the present invention, the pre-collagen fiber 203-4 includes: pre-I collagen fiber 203-4Ⅰ, pre-II collagen fiber 203-4Ⅱ and pre-III collagen fiber 203-4Ⅲ, which are distributed sequentially along the thickness direction of the pre-limiting ring and intertwine with each other in the midline region to form a fiber cross-linking structure.

[0026] In a preferred embodiment of the present invention, the pre-collagen fiber 203-4 and the post-collagen fiber 201-2 are cylindrical.

[0027] In a preferred embodiment of the present invention, the front III collagen fibers 203-4III disposed in the outer fiber layer 203-3 branch downward and outward from the upper end at the midline. The distribution of the front III collagen fibers that diffuse outward towards the outer side results in the angle between the front III collagen fibers 203-4III and the surface of the outer fiber layer 203-3 gradually increasing from the midline to both sides, and the two sides are symmetrically distributed. The tilt angle range is 0°-65°, with the tilt angle at the centerline being 0° and the tilt angle at the outermost edge being 65°.

[0028] In a preferred embodiment of the present invention, the front II collagen fiber 203-4Ⅱ is located between the outer fiber layer 203-3 and the intermediate transition layer 203-2, and the front I collagen fiber 203-4Ⅰ is located between the intermediate transition layer 203-2 and the inner fiber layer 203-1. The two ends of the front II collagen fiber 203-4Ⅱ and the front I collagen fiber 203-4Ⅰ extend upward from the lower end of the outer side and towards the middle, gradually converging along the midline direction and intertwining with each other in the middle region. The inclination angle between the front II collagen fiber 203-4Ⅱ and the surface of the intermediate transition layer 203-2, and the inclination angle between the front I collagen fiber 203-4Ⅰ and the surface of the inner fiber layer 203-1, both gradually decrease from the outermost side to the middle and are symmetrically distributed on both sides. The inclination angle ranges from 45° to 65°, with the inclination angle near the midline being 45° and the inclination angle at the outermost side being 65°.

[0029] In a preferred embodiment of the present invention, the upper endplate 1, the lower endplate 3, the upper endplate fixation tooth 101, and the lower endplate fixation tooth 301 are all graphene nanosheet-reinforced conductive polyetheretherketone composite materials; specifically, 2 wt% graphene nanosheets are added to the polyetheretherketone matrix by melt blending, which improves the conductivity of the material, promotes the conduction of electrical signals of adjacent vertebral cells, and accelerates bone integration based on matching medical material production standards.

[0030] In a preferred embodiment of the present invention, the anterior fiber ring 203 and the posterior fiber ring 201 are polyurethane polymer materials with different elastic moduli. In order to ensure the fatigue resistance of the anterior fiber ring 203, and since the posterior fiber ring 201 accounts for a smaller proportion, in order to prevent the nucleus pulposus 202 from detaching from the posterior side, the elastic modulus of the posterior fiber ring 201 material is selected to be higher than that of the anterior fiber ring 203.

[0031] In a preferred embodiment of the present invention, the nucleus pulposus 202 is a thermoplastic polyurethane rubber material, which has the advantages of good elasticity and strong shock absorption.

[0032] In a preferred embodiment of the present invention, the upper surface of the upper endplate 1, the lower surface of the lower endplate 3, the surface of the upper endplate fixing teeth 101, and the surface of the lower endplate fixing teeth 301 are all coated with a composite antibacterial coating containing 0.5 wt% silver ions and hydroxyapatite by plasma spraying. Specifically, hydroxyapatite powder and 0.5 wt% silver ion antibacterial powder are uniformly mixed and sprayed at high speed onto the pretreated structural surface using plasma spraying. After cooling, a dense composite coating is formed, which ensures that the coating is firmly bonded to the endplate substrate and effectively resists the impact during cervical spine movement. At the same time, the 0.5 wt% silver ions can avoid the cytotoxicity caused by excessive silver ions, meet the ISO 22196 antibacterial standard, and ensure biocompatibility between the artificial cervical intervertebral disc and adjacent vertebrae after implantation.

[0033] The overall structural design is adapted to the movement requirements of the cervical uncinate process joint, enabling the cervical spine to perform various movements such as flexion and extension, lateral bending, axial rotation and translation, and coupled movements. When the cervical spine moves, the vertical load is first transmitted through the upper endplate 1 and the lower endplate 3 to the interior of the elastic core 2 in the middle. The nucleus pulposus 202 in the elastic core 2 deforms accordingly with the movement of the cervical spine under stress. This deformation will exert a compressive effect on the surrounding anterior annulus fibrosus 203 and posterior annulus fibrosus 201. Since the anterior and posterior annulus fibrosus are composed of multiple fiber layers (inner fiber layer 203-1, intermediate transition layer 203-2, and outer fiber layer 203-3) and collagen fibers (anterior collagen fibers 203-4 and posterior collagen fibers 201-2) at different locations, the deformation of the nucleus pulposus 202 will cause the fiber layers and collagen fibers at different locations to be compressed to different degrees, thereby causing each collagen fiber to produce different tensile effects under stress.

[0034] The medial fibrous layer 203-1 and the posterior fibrous layer 201-1 are arranged differently, and this structural difference helps the nucleus pulposus 202 to achieve elastic deformation under stress. At the same time, the collagen fibers inside the annulus fibrosus have different inclination angles. The differentiated design of fiber inclination angles allows the mechanical properties of different regions of the annulus fibrosus to be controlled, thereby forming an anisotropic distribution of mechanical properties inside the artificial cervical intervertebral disc.

[0035] Through the above structure, the artificial cervical intervertebral disc can provide similar support and deformation capacity as the natural cervical intervertebral disc in different directions and under different movement states after implantation, so that it can more naturally match the physiological movement law of the vertebrae in actual use.

[0036] This invention replicates the structure and configuration of a biological cervical intervertebral disc, employing differentiated arrangement of the anterior and posterior annulus fibrosus, gradient tilt design of collagen fibers, elastic deformation characteristics of the nucleus pulposus, and combinations of materials with different elastic moduli. This allows the artificial cervical intervertebral disc to more naturally match the physiological movement of the vertebrae after implantation. The irregularly shaped endplate better conforms to the uncinate process joints of the cervical vertebrae, accommodating complex movements in multiple directions. By utilizing the structural and distributional differences between the anterior and posterior collagen fibers, the mechanical properties of different regions can be regulated, thereby achieving anisotropic mechanical characteristics. Furthermore, the use of graphene-reinforced materials in the upper and lower endplates, combined with an antibacterial coating containing silver ions and hydroxyapatite, enhances biocompatibility and reduces artifacts during CT scans, thus improving the accuracy of imaging interpretation.

[0037] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An artificial cervical intervertebral disc based on a biomimetic structure, characterized in that, It includes an upper endplate (1), a lower endplate (3), and an elastomeric core (2) disposed between the upper endplate (1) and the lower endplate (3); the elastomeric core (2) includes an anterior annulus fibrosus (203), a nucleus pulposus (202), and a posterior annulus fibrosus (201); the anterior annulus fibrosus (203) is composed of an outer fibrous layer (203-3), an intermediate transition layer (203-2), an inner fibrous layer (203-1), and anterior collagen fibers (203-4); the posterior annulus fibrosus (201) It consists of a posterior fiber layer (201-1) and equidistantly arranged posterior collagen fibers (201-2); the nucleus pulposus (202) is elliptical and accounts for 50%-60% of the top view area of ​​the elastomer core (2); the upper endplate (1) and the lower endplate (3) are both arc-shaped structures with both ends curving outward and upward, and both ends of the upper endplate (1) and the lower endplate (3) extend upward to form tips, and the upper endplate (1) and the lower endplate (3) are in contact with the surface of the elastomer core (2); The upper end plate (1) has an upper end plate fixing tooth (101) on the side away from the elastomer core (2), and the lower end plate (3) has a lower end plate fixing tooth (301) on the side away from the elastomer core (2).

2. The artificial cervical intervertebral disc based on a biomimetic structure according to claim 1, characterized in that, The rear fiber ring (201) is a ring-shaped structure with uniform thickness.

3. The artificial cervical intervertebral disc based on a biomimetic structure according to claim 2, characterized in that, The anterior annulus fibrosus (203) is an arc-shaped structure. The thickness of the middle part of the anterior annulus fibrosus (203) is greater than the thickness of both ends. Both the anterior annulus fibrosus (203) and the posterior annulus fibrosus (201) surround and enclose the nucleus pulposus (202).

4. The artificial cervical intervertebral disc based on a biomimetic structure according to claim 3, characterized in that, The procollagen fiber (203-4) includes: proI collagen fiber (203-4Ⅰ), proII collagen fiber (203-4Ⅱ) and proIII collagen fiber (203-4Ⅲ).

5. The artificial cervical intervertebral disc based on a biomimetic structure according to claim 4, characterized in that, The procollagen fibers (203-4) and posterior collagen fibers (201-2) are cylindrical.

6. The artificial cervical intervertebral disc based on a biomimetic structure according to claim 5, characterized in that, The anterior III collagen fibers (203-4Ⅲ) arranged in the outer fiber layer (203-3) branch downward and outward from the upper end at the midline. The distribution pattern of the anterior III collagen fibers spreading outward further outward results in the angle between the anterior III collagen fibers (203-4Ⅲ) and the surface of the outer fiber layer (203-3) increasing from the midline to both sides, and the distribution is symmetrical on both sides. The tilt angle range is 0°-65°, with the tilt angle at the centerline being 0° and the tilt angle at the outermost edge being 65°.

7. The artificial cervical intervertebral disc based on a biomimetic structure according to claim 6, characterized in that, The pre-II collagen fiber (203-4Ⅱ) is located between the outer fiber layer (203-3) and the intermediate transition layer (203-2), and the pre-I collagen fiber (203-4Ⅰ) is located between the intermediate transition layer (203-2) and the inner fiber layer (203-1). The two ends of the pre-II collagen fiber (203-4Ⅱ) and the pre-I collagen fiber (203-4Ⅰ) extend upward from the lower end of the outer side and towards the middle, converging along the outer side towards the midline and finally intertwining in the middle region. The inclination angle between the pre-II collagen fiber (203-4Ⅱ) and the surface of the intermediate transition layer (203-2), and the inclination angle between the pre-I collagen fiber (203-4Ⅰ) and the surface of the inner fiber layer (203-1) both decrease from the outermost side to the middle and are symmetrically distributed on both sides. The inclination angle ranges from 45° to 65°, with the inclination angle near the midline being 45° and the inclination angle at the outermost side being 65°.

8. The artificial cervical intervertebral disc based on a biomimetic structure according to claim 7, characterized in that, The upper endplate (1), lower endplate (3), upper endplate fixing teeth (101), and lower endplate fixing teeth (301) are all graphene nanosheet-reinforced conductive polyether ether ketone composite materials; the front fiber ring (203) and rear fiber ring (201) are polyurethane polymer materials with different elastic moduli; the core (202) is a thermoplastic polyurethane rubber material.

9. The artificial cervical intervertebral disc based on a biomimetic structure according to claim 8, characterized in that, The upper surface of the upper end plate (1), the lower surface of the lower end plate (3), the surface of the upper end plate fixing tooth (101), and the surface of the lower end plate fixing tooth (301) are all coated with a composite antibacterial coating containing 0.5wt% silver ions and hydroxyapatite by plasma spraying.

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