A combined elastic artificial intervertebral disc

Abstract

The present invention discloses a combined elastic artificial intervertebral disc, comprising an upper end plate, a lower end plate, a capsule, and a multilayer nucleus pulposus structure composed of at least three layers of nucleus pulposus elastic rings; the inner diameter of each layer of nucleus pulposus elastic ring of the multilayer nucleus pulposus structure increases from the inside to the outside, the capsule is wrapped around the outer periphery of the outermost layer of nucleus pulposus elastic ring, and the nucleus pulposus elastic ring and the capsule are fixedly engaged between the upper end plate and the lower end plate; a gap is left between each layer of nucleus pulposus elastic ring, and the nucleus pulposus elastic rings of different layers do not contact during assembly and deformation. The present invention can effectively solve the technical problem that the existing artificial intervertebral disc has the risk of friction debris, and the technical problem that the mechanical properties of the artificial intervertebral disc in the prior art are not close to those of the normal intervertebral disc of the human body.

Description

Technical Field

[0001] The invention belongs to the technical field of artificial intervertebral discs and relates to a combined elastic artificial intervertebral disc. Background Art

[0002] Spinal degeneration caused by disc herniation or prolapse is a common disease. It is reported that the number of patients with cervical and lumbar diseases in my country has reached nearly 200 million, and the age of patients is showing a trend of getting younger. For more serious disc diseases, when conservative treatment is ineffective, surgical treatment is the only option. In recent years, a new type of spinal surgical treatment has emerged in clinical practice, which is to replace the diseased disc with an artificial disc that can be moved, which can achieve the effect of restoring and maintaining the mobility and stability of the surgical segment of the spine.

[0003] The structure of artificial intervertebral disc products currently on the market or products publicly reported in patent documents basically adopts a "ball and socket" friction hard support design. Specifically, the structure of artificial intervertebral disc can be divided into sliding friction type and elastic deformation type in terms of activity mode. Sliding friction type artificial intervertebral discs are mostly artificial intervertebral discs similar to ball and socket structures, such as the structures disclosed in patents CN1913846B and CN201977964U. This type of artificial intervertebral disc is generally made of metal or plastic materials, and movement is achieved through sliding friction between different components. Because it is made of metal or plastic materials, it cannot axially absorb shock and absorb the vibration of the spine. Due to friction movement, there is a long-term risk of friction and wear. Its biomechanical properties are also quite different from those of normal intervertebral discs. Elastic deformation type artificial intervertebral discs generally use a piece of elastic material as the nucleus pulposus, placed between two end plates made of metal or hard plastic, and use the deformation of the middle elastic nucleus pulposus to achieve movement. For example, patent CN 209316158U discloses an elastic nucleus pulposus composed of a butterfly spring group, patent CN 110025408A discloses an elastic nucleus pulposus made of metal rubber formed by metal wire stamping, and CN202027749U discloses an elastic nucleus pulposus made of elastomeric materials. Most of these nucleus pulposus materials are of a single material, while normal human intervertebral discs are composed of gel-like substances, annular fiber matrix, and fibers, and have anisotropic properties. Therefore, artificial intervertebral discs made of nucleus pulposus materials made of a single material are difficult to simulate the biomechanical properties of normal intervertebral discs. Patent CN 109381282A discloses an artificial intervertebral disc composed of an elastic support body with a middle hole and a support rod located in the middle hole. Its nucleus pulposus is composed of two component materials. Its effect of simulating the biomechanical properties of normal human intervertebral discs may be improved to a certain extent compared to a single material, but the effect is limited. At the same time, the friction interface and wear risk will increase between the support body and the support rod. It can be seen that the above elastically deformed intervertebral disc can achieve the shock-absorbing function, but there is still a risk of wear and the biomechanical properties are still quite different from those of normal intervertebral discs.

[0004] From the above, it can be seen that the mechanical properties of the artificial intervertebral disc structure disclosed in the prior art are quite different from the biomechanical properties of the normal cervical intervertebral disc. The clinical manifestations are mainly the increased range of motion of the implanted segment, which causes increased stress in the surrounding small joints and ligament tissues. The product has the risk of friction debris in long-term use and cannot effectively absorb external force shock. Therefore, how to achieve better shock absorption, reduce wear debris, and achieve mechanical properties close to those of normal human intervertebral discs has become a hot spot and difficulty in current research. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a combined elastic artificial intervertebral disc, one of the problems to be solved is to effectively solve the technical problem of the risk of grinding debris in the existing artificial intervertebral disc.

[0006] The second problem solved by the combined elastic artificial intervertebral disc of the present invention is to solve the technical difficulty that the mechanical properties of the artificial intervertebral disc in the prior art are not close to those of the normal intervertebral disc of the human body.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention discloses a combined elastic artificial intervertebral disc, comprising an upper end plate, a lower end plate, a capsule, and a multi-layer nucleus pulposus structure composed of at least three layers of nucleus pulposus elastic rings;

[0009] The inner diameter of each layer of the nucleus pulposus elastic ring of the multi-layer nucleus pulposus structure increases from the inside to the outside, the capsule is wrapped around the outer periphery of the outermost layer of the nucleus pulposus elastic ring, and the nucleus pulposus elastic ring and the capsule are fixedly engaged between the upper end plate and the lower end plate; a gap is left between each layer of the nucleus pulposus elastic ring, and during the assembly and molding process, the nucleus pulposus elastic rings between different layers do not contact each other.

[0010] Preferably, the nucleus pulposus elastic ring is made of an elastomeric material; the moduli of different layers of nucleus pulposus elastic rings are different, and the moduli decrease from the center to the periphery.

[0011] Preferably, the envelope is made of elastic material, and the surface of the envelope is smooth or provided with corrugated lines.

[0012] Preferably, the gaps between adjacent nucleus pulposus elastic rings are filled with a lubricating medium.

[0013] Preferably, the lubricating medium is gas or physiological saline.

[0014] Preferably, a matching structure for clamping and fixing a plurality of layers of nucleus pulposus elastic rings and capsules is provided on the surface of the upper end plate and the lower end plate that contacts the nucleus pulposus elastic ring.

[0015] Further preferably, the matching structure is a groove.

[0016] More preferably, the cross section of the groove is chamfered, T-shaped or corrugated.

[0017] Preferably, the cross-sectional curves of the nucleus pulposus elastic rings in different layers are the same or different, and the cross-sectional curve is a straight line, an arc line or a wavy line.

[0018] Preferably, spikes for contacting vertebrae are provided on the upper surface of the upper end plate and the lower surface of the lower end plate; and pure titanium coating or hydroxyapatite coating is coated on the upper surface of the upper end plate and the lower surface of the lower end plate.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The combined elastic artificial intervertebral disc disclosed by the present invention, firstly, has gaps between the elastic rings of the multiple layers of the nucleus pulposus structure constituting the artificial intervertebral disc, and they do not contact each other during normal use, assembly, and deformation, which can effectively avoid the generation of wear debris due to sliding friction; secondly, the outermost layers of the multiple layers of the nucleus pulposus elastic rings are provided with a capsule to avoid the risk of leakage of the wear debris generated. Thirdly, the structure is an assembled structure with simple processing and assembly processes, which can effectively reduce the manufacturing cost. The combined elastic artificial intervertebral disc of the present invention can effectively solve the technical problem of the risk of grinding debris in existing artificial intervertebral discs.

[0021] Furthermore, the nucleus pulposus elastic ring of the combined elastic artificial intervertebral disc of the present invention is a multi-layer gradient elastomer structure, which is composed of an elastomer material, and the modulus of the nucleus pulposus elastic rings in different layers is different, and the modulus decreases from the center to the periphery. It has been verified by experiments that it can achieve biomechanical properties similar to those of a normal intervertebral disc.

[0022] Furthermore, filling the gap between adjacent nucleus pulposus elastic rings with a lubricating medium can provide a certain lubrication for the movement and deformation of the nucleus pulposus material and reduce possible interface friction.

[0023] Furthermore, the nucleus pulposus elastic ring or capsule is fixed by means of grooves provided on the upper end plate and the lower end plate. The provision of the grooves not only facilitates the assembly and connection of the nucleus pulposus elastic ring, but also enables accurate positioning of different layers of nucleus pulposus elastic rings.

[0024] Furthermore, the cross section of the groove is chamfered, T-shaped or corrugated, because the rough surface makes it easier to firmly assemble the elastic ring of the nucleus pulposus or the capsule, making the fixation more stable.

[0025] Furthermore, the contact surfaces of the upper end plate and the lower end plate with the vertebrae are provided with spikes and are also coated with a pure titanium coating or a hydroxyapatite coating, which helps to achieve long-term fixation of the vertebrae after the artificial intervertebral disc is implanted. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is an exploded view of the structure of various parts of the artificial intervertebral disc according to the disclosed embodiment of the present invention.

[0027] Figure 2 This is an assembly diagram of the overall structure of an artificial intervertebral disc according to an embodiment of the present invention.

[0028] Figure 3 It is a cross-sectional view of the structure of the artificial intervertebral disc nucleus pulposus according to the embodiment disclosed in the present invention; wherein (a) is a cross-sectional schematic diagram; and (b) is a component schematic diagram.

[0029] Figure 4 Schematic diagram of different curved surfaces and different numbers of layers of the artificial intervertebral disc nucleus pulposus structure according to the disclosed embodiment of the present invention; wherein, (a) straight line; (b) curve; (c) wavy line; (d) four layers; (e) five layers.

[0030] Figure 5 Schematic diagrams of different curved surfaces of the contact surface between the nucleus pulposus and the end plate of the artificial intervertebral disc of the disclosed embodiment of the present invention; wherein (a) is a chamfered type; (b) is a partial enlarged view of A in the figure; (c) is a T-slot; (d) is a partial enlarged view of B in the figure; (e) is a corrugated type; (f) is a partial enlarged view of C in the figure;

[0031] Figure 6 This is a diagram of scoliosis deformation of an artificial intervertebral disc according to an embodiment of the present invention.

[0032] Figure 7 This is a comparison diagram of the mechanical properties of the artificial cervical intervertebral disc implemented in the present invention after being implanted in the vertebrae and applying the same torque.

[0033] Among them: 1-upper end plate; 2-outer layer of nucleus pulposus; 3-middle layer of nucleus pulposus; 4-inner layer of nucleus pulposus; 5-capsule; 6-lower end plate. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0035] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0036] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0037] like Figure 1 As shown, this embodiment provides a combined elastic artificial intervertebral disc, which is composed of an upper end plate 1, a lower end plate 6, a multi-layer nucleus pulposus composed of at least three layers of elastic rings, and a capsule 5. The multi-layer nucleus pulposus is composed of three or more layers of elastic rings, such as Figure 1 The outer layer 2, the middle layer 3, and the inner layer 4 of the nucleus pulposus shown have intervals between different layers, and the different layers do not contact each other during assembly and deformation. The nucleus pulposus is made of elastic material, and each layer of the elastic ring of the nucleus pulposus is made of a material with the same modulus. The modulus of the materials between different layers is different, and the modulus decreases from the inner layer to the outer layer. The different layers of the nucleus pulposus can be separated by gas or filled with physiological saline. The physiological saline is preferably used to lubricate the movement and deformation of the nucleus pulposus material to a certain extent and reduce the possible interface friction. The capsule 5 is wrapped around the outer layer 2 of the nucleus pulposus, wrapping the entire nucleus pulposus, and connected to the upper end plate 1 and the lower end plate 6. The capsule and the outermost layer of the nucleus pulposus are not in contact in structure, but may contact when the elastic ring is deformed. The surface of the capsule 5 is a smooth and flat film or a curved corrugated line, and the curved corrugated line is preferred. The upper end plate 1 and the lower end plate 6 are provided with a matching structure on the surface in contact with the nucleus pulposus, which can firmly clamp different nucleus pulposus layers and capsules to achieve a fixed assembly effect. The upper end plate 1 and the lower end plate 6 are provided with spikes on the contact surface with the vertebrae, which can realize timely fixation with the vertebrae after the artificial intervertebral disc is implanted. The upper end plate 1 and the lower end plate 6 are coated with pure titanium or hydroxyapatite coating on the contact surface with the vertebrae, which helps to realize the vertebrae growth after the artificial intervertebral disc is implanted and realize long-term fixation.

[0038] like Figure 2 As shown, the combined elastic artificial intervertebral disc of the present invention is assembled before surgical implantation, and then conveniently implanted between the vertebrae of the surgical segment in the form of a complete component.

[0039] like Figure 3As shown, there are gaps between different layers of the nucleus pulposus, and the modulus decreases from the inner layer 4 of the nucleus pulposus to the outer layer of the nucleus pulposus. The number of nucleus pulposus layers can be three or more. When the nucleus pulposus has four or more layers, the number of layers of the middle layer 3 of the nucleus pulposus is two or more. The nucleus pulposus material can be one or both of polyurethane and silicone rubber, and different layers can be the same material or different materials. The gradient elastic modulus of the nucleus pulposus is in the range of 0.05-150Mpa.

[0040] like Figure 4 As shown, the elastic rings of different layers of the nucleus pulposus can have different cross-sectional curves, which can be straight lines, Figure 4 As shown in Figure (a); it can be a concave arc, Figure 4 As shown in Figure (b); it can be a wavy line, Figure 4 As shown in Figure (c), different cross sections have different degrees of deformation and stress, and arc or wavy lines are relatively better. In addition, the number of nucleus pulposus layers is three or more, and the figure shows three and four layers ( Figure 4 (d)) and five layers ( Figure 4 (e) as shown in the figure.

[0041] See also Figure 5 The upper end plate 1 and the lower end plate 6 mentioned above are provided with a mating knot on the surface in contact with the nucleus pulposus. The mating structure can be a groove, and the cross-section of the groove can be chamfered (as shown in (a) and (b) in the figure), T-shaped (as shown in (c) and (d) in the figure) or corrugated (as shown in (e) and (f) in the figure), as well as other structures that are easy to firmly assemble the nucleus pulposus and the elastic membrane.

[0042] like Figure 6 As shown, during the deformation of the artificial intervertebral disc, different layers of the nucleus pulposus do not contact each other, and friction with each other will not cause wear debris. The nucleus pulposus and the capsule 5 will not fall out of the matching structure of the upper end plate 1 and the lower end plate 6, further reducing the risk of wear debris generation and leakage.

[0043] like Figure 7 As shown, it shows the biomechanical comparison between artificial intervertebral discs with different moduli of nucleus pulposus and normal intervertebral discs during flexion. Curve a is an artificial intervertebral disc containing a single low modulus nucleus pulposus, curve b is an artificial intervertebral disc containing two layers of gradient modulus nucleus pulposus, curve c is an artificial intervertebral disc containing three layers of gradient modulus nucleus pulposus, curve d is an artificial intervertebral disc containing four layers of gradient modulus nucleus pulposus, curve e is a normal intervertebral disc, and curve f is an artificial intervertebral disc containing a single high modulus. It can be seen from the biomechanical performance curves in the figure that the biomechanical curves of artificial intervertebral discs containing three and four layers of gradient modulus are the closest to the biomechanical curves of normal intervertebral discs. Therefore, gradient modulus intervertebral discs with three or more layers have more biomimetic performance than artificial intervertebral discs with single or two layers of nucleus pulposus.

[0044] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A combined elastic artificial intervertebral disc, characterized in that: The multi-layer nucleus pulposus structure comprises an upper end plate (1), a lower end plate (6), a capsule (5), and at least three layers of nucleus pulposus elastic rings; The inner diameter of each layer of the nucleus pulposus elastic ring of the multi-layer nucleus pulposus structure increases from the inside to the outside, the capsule (5) is wrapped around the outer periphery of the outermost layer of the nucleus pulposus elastic ring, and the nucleus pulposus elastic ring and the capsule (5) are fixedly engaged between the upper end plate (1) and the lower end plate (6); a gap is left between each layer of the nucleus pulposus elastic ring, and during the assembly and deformation process, the nucleus pulposus elastic rings of different layers do not contact each other; The nucleus pulposus elastic ring is made of an elastomeric material, and the moduli of different layers of nucleus pulposus elastic rings are different, and the moduli decrease from the center to the periphery; the gaps between adjacent nucleus pulposus elastic rings are filled with lubricating medium.

2. The combined elastic artificial intervertebral disc according to claim 1, characterized in that: The envelope (5) is made of an elastic material, and the surface of the envelope (5) is smooth or provided with corrugated lines.

3. The combined elastic artificial intervertebral disc according to claim 1, characterized in that: The lubricating medium is gas or physiological saline.

4. The combined elastic artificial intervertebral disc according to any one of claims 1 to 3, characterized in that: A matching structure for clamping and fixing a plurality of layers of nucleus pulposus elastic rings and a capsule (5) is provided on the surface of the upper end plate (1) and the lower end plate (6) that contacts the nucleus pulposus elastic ring.

5. The combined elastic artificial intervertebral disc according to claim 4, characterized in that: The matching structure is a groove.

6. The combined elastic artificial intervertebral disc according to claim 5, characterized in that: The cross section of the groove is chamfered, T-shaped or corrugated.

7. The combined elastic artificial intervertebral disc according to any one of claims 1 to 3, characterized in that: The cross-sectional curves of the elastic rings of the nucleus pulposus in different layers are the same or different, and the cross-sectional curves are straight lines, arc lines or wavy lines.

8. The combined elastic artificial intervertebral disc according to any one of claims 1 to 3, characterized in that: Spikes for contacting vertebrae are provided on the upper surface of the upper end plate (1) and the lower surface of the lower end plate (6); and pure titanium coating or hydroxyapatite coating is coated on the upper surface of the upper end plate (1) and the lower surface of the lower end plate (6).

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