Anti-fatigue fracture bionic intervertebral disc
Technical Field
The invention relates to a fatigue fracture resistant bionic intervertebral disc, and belongs to the technical field of medical instruments.
Background
The intervertebral disc is an important part of the spine of a human body, and with the increase of the age, the gradual aging or damage of the intervertebral disc of the human body can cause single-segment or multi-segment intervertebral disc degenerative diseases, so that continuous pain is caused, the intervertebral disc becomes one of main skeletal muscular system diseases in the world, the life quality of a patient is seriously influenced, and a heavy economic burden is brought to the family of the patient. Currently, disc replacement is an effective method for treating degenerative disc disease, and has the functions of maintaining intervertebral height, preserving segment motion capability and reducing adjacent joint degeneration.
The traditional artificial intervertebral disc product mainly comprises an upper end plate, a lower end plate and a core, wherein the core and the upper end plate are connected in a ball-and-socket joint mode, and the motion characteristics of human intervertebral discs can be simulated by utilizing the characteristics of the joints. Compared with the human biological intervertebral disc, the human biological intervertebral disc has the motion characteristic of 6 degrees of freedom, and the traditional artificial intervertebral disc product only has partial motion characteristic.
Meanwhile, the upper end plate, the core and the lower end plate of the traditional artificial intervertebral disc are mostly rigid members, and the contact mode of the core and the upper end plate and the contact mode of the core and the lower end plate are mainly rigid contact, so that the stress concentration of the contact surface is easily caused in the reciprocating motion process, and the phenomenon of fatigue fracture is caused, so that the service life of the traditional artificial intervertebral disc is short, and the problems of adverse accidents or secondary operations and the like are caused. Therefore, the demand for designing a bionic intervertebral disc with high fatigue strength is urgent, and the effective prolonging of the service life and the period of the bionic intervertebral disc in vivo is one of the key problems which need to be solved urgently in the development of the traditional artificial intervertebral disc.
Disclosure of Invention
In order to solve the problems of the traditional artificial intervertebral disc products, the invention aims to provide a bionic intervertebral disc capable of resisting fatigue fracture; meanwhile, the human intervertebral disc has the 6-freedom-degree motion characteristic of the human intervertebral disc.
In order to achieve the purpose, the invention takes the human biological intervertebral disc as a blue book and is inspired according to the gradient characteristic of the human biological intervertebral disc.
The biological intervertebral disc of the human body is in the long-term natural selection and evolution process, the tissue structure, material characteristics and performance of the biological intervertebral disc are continuously optimized and improved, the biological intervertebral disc is composed of nucleus pulposus and fibrous ring, the main component of the nucleus pulposus is proteoglycan gel substance with more water content, the biological intervertebral disc is rich in elasticity and has lower rigidity, the main component of the fibrous ring is collagen, the inner layer has lower rigidity according to the hardness classification of the material, and compared with the outer layer of the inner layer, the biological intervertebral disc has higher rigidity. The biological intervertebral disc has gradient characteristics through a special tissue structure and material properties of soft and hard layering, and shows high excellent fatigue fracture resistance in the complex reciprocating motion process of a human body. The biological intervertebral disc realizes the optimized distribution of local mechanical properties by utilizing the gradient characteristics, effectively avoids stress concentration, thereby improving the fatigue fracture resistance and providing a good idea for the design of the bionic intervertebral disc.
Based on the gradient characteristics of the human biological intervertebral disc, the invention adopts the following technical scheme:
a bionic intervertebral disc resisting fatigue fracture is composed of an upper end plate, a lower end plate and a core, wherein one end of the core is fixed to the lower portion of the upper end plate, and the other end of the core is fixed to the upper portion of the lower end plate.
The core comprises a nucleus pulposus and an annulus fibrosus, the nucleus pulposus being composed of a polymeric material; the fiber ring is a functional gradient material and is formed by polymerizing two or more polymer materials with different moduli.
The elastic modulus of the outer surface of the fiber ring is the largest, the elastic modulus of the inner surface of the fiber ring is the smallest, and the elastic modulus of the fiber ring gradually decreases from the outer surface to the inner surface and changes in a continuous gradient manner.
The modulus of elasticity of the inner surface of the annulus is equal to the modulus of elasticity of the outer surface of the nucleus pulposus.
The overall configuration of the upper end plate, the core and the lower end plate is D-shaped.
The upper end plate and the lower end plate are both provided with spikes.
The upper end plate, the lower end plate and the spikes are all made of polymer materials. The polymer material can be selected from ultra-high molecular weight polyethylene or polyether-ether-ketone or thermoplastic polyurethane elastomer rubber.
The upper part of the upper end plate, the lower part of the lower end plate and the outer surface of the sharp thorn are provided with a titanium coating, a hydroxyapatite coating or a calcium carbonate coating, and the coating material can also be other bioactive materials.
Compared with the traditional artificial intervertebral disc product, the invention has the following beneficial effects:
1. through core deformation, the upper end plate and the lower end plate generate relative motion, 6-degree-of-freedom motion characteristics of flexion, extension, lateral bending, rotation, translation and the like of the human intervertebral disc can be simulated, and the problem that the traditional artificial intervertebral disc only has partial motion characteristics is solved.
2. The core has the gradient characteristic similar to that of human body biological intervertebral, the elastic modulus is in continuous gradient change, compared with the traditional artificial intervertebral disc product, the gradient has better fatigue fracture resistance, and the stress concentration can be effectively avoided in the long-term reciprocating motion process and under the same condition, so that the service life of the product is prolonged. Meanwhile, the overall configuration of the upper end plate, the core and the lower end plate is similar to a D shape and is close to the shape of a human biological intervertebral disc, the stress area is increased, stress concentration is avoided, and the anti-fatigue strength of the product can be improved.
3. The spikes help to maintain the stability of the product and the titanium coating helps to be biocompatible with the vertebrae.
Drawings
FIG. 1 is a schematic view of the structure of the present invention.
FIG. 2 is a schematic diagram of the core structure of the present invention.
Fig. 3 is a schematic diagram of a core variation of the present invention.
In the figure: 10-upper end plate; 20-a core; 21-nucleus pulposus; 22-fiber ring; 30-lower end plate; 40-spike.
Detailed Description
As shown in fig. 1, the bionic intervertebral disc resisting fatigue fracture comprises an upper end plate 10, a core 20 and a lower end plate 30, wherein one end of the core 20 is fixed at the lower part of the upper end plate 10, and the other end of the core 20 is fixed at the upper part of the lower end plate 30.
As shown in fig. 2, the core 20 is composed of a nucleus pulposus 21 and an annulus fibrosus 22, and the nucleus pulposus 21 is a thermoplastic polyurethane elastomer rubber material; the fiber ring 22 is a functional gradient material and is formed by polymerizing two or more thermoplastic polyurethane elastomer rubber materials with different moduli, the elastic modulus of the outer surface of the fiber ring 22 is the largest, the elastic modulus of the inner surface of the fiber ring 22 is the smallest, the elastic modulus of the fiber ring 22 gradually decreases from the outer surface to the inner surface and is in continuous gradient change, the elastic modulus of the inner surface of the fiber ring 22 is equal to the elastic modulus of the outer surface of the nucleus pulposus 21, under the action of alternating load, a low elastic modulus area of the core 20 can generate relatively large deformation, the deformation of a high elastic modulus area is small, and in the long-term reciprocating motion process and under the same condition, the load can be absorbed and dispersed to the periphery by using flexibility, so that the.
The upper end plate 10, the core 20 and the lower end plate 30 are D-shaped in overall configuration, the shape of the upper end plate, the core 20 and the lower end plate is close to the shape of a human biological intervertebral disc, the stress area is increased, stress concentration is avoided, and the fatigue resistance of the product is improved.
As shown in figure 3, the upper end plate 10 and the lower end plate 30 can generate relative motion by deforming the core 20, so that the motion characteristics of 6 degrees of freedom such as flexion, extension, lateral bending, rotation, translation and the like of the human intervertebral disc are simulated, and the problem that only part of the motion characteristics of the traditional artificial intervertebral disc are reserved is solved.
The upper end plate 10 and the lower end plate 30 are provided with spikes 40, which is beneficial to maintaining the stability of the product.
The upper end plate 10, the lower end plate 30 and the spikes 40 are made of polymer materials. The polymer material can be selected from ultra-high molecular weight polyethylene or polyether-ether-ketone or thermoplastic polyurethane elastomer rubber.
The upper part of the upper end plate 10, the lower part of the lower end plate 30 and the outer surface of the spine 40 are coated with titanium coating or hydroxyapatite coating or calcium carbonate coating to promote the regeneration and fusion of vertebrae.