CN114053485B - Single cell structure for biological stent and application thereof - Google Patents

Abstract

The invention belongs to the technical field related to biomass structure, and more specifically relates to a unit cell structure used for a biological scaffold and its application. The unit cell structure is connected by a plurality of biconical rods to form a Diamond structure configuration, wherein the biconical rods include two circular frustums, and the bottoms of the two circular frustums overlap to form a shape with two small ends and a large middle, On the one hand, this shape reduces the rigidity and strength of the structure, avoiding the stress shielding effect of the biological scaffold, on the other hand, when the nutrient solution passes through the protruding part in the middle, a turbulent flow phenomenon is formed, the material flows quickly, and the metabolism is accelerated. The invention solves the technical problem that the traditional lattice structure design cannot simultaneously satisfy the mechanical and mass transfer performances and match the natural bones.

Description

A kind of unit cell structure for biological support and its application

technical field

The invention belongs to the technical field related to biomass structure, and more specifically relates to a unit cell structure used for a biological scaffold and its application.

Background technique

With the development of bioengineering technology, doctors have put forward urgent needs and requirements for bioscaffolds of surgical bone implants. Lattice structure is a new type of multifunctional metamaterial that has emerged with the rapid development of additive manufacturing technology in the field of material processing in recent years. It has the advantage of realizing the integration of material-structure-function.

The lattice structure has a high relative density. Through the design of the position, size and material distribution of the rods, the lattice structure has a relative density, elastic modulus, yield strength and mass transfer performance suitable for human bones, making it compatible with bone The missing part has a perfect fit to promote osteoblast proliferation and repair of the implant bioscaffold. In addition, human bones have non-uniform distribution of mechanical properties. Through the periodic/non-periodic arrangement of the lattice structure, the structural gradient can be designed to meet the mechanical performance requirements of relative density, elastic modulus and strength, but the gradient The designed components will have uneven permeability distribution, which will greatly reduce the mass transfer performance, especially the gradient layer with the highest relative density will greatly reduce its mass transfer performance. This is not only detrimental to bone repair, but also may produce a stress shielding effect, leading to failure of the implant and endangering human health.

Contents of the invention

In view of the above defects or improvement needs of the prior art, the present invention provides a unit cell structure for biological scaffolds and its application, through the design of the biconical rod structure of the unit cell structure and the overall unit cell structure structure In order to solve the technical problem that the traditional lattice structure design cannot satisfy the mechanical and mass transfer properties at the same time and match the natural bone.

In order to achieve the above object, according to one aspect of the present invention, there is provided a unit cell structure for a biological scaffold, characterized in that the unit cell structure is connected by a plurality of biconical rods to form a Diamond structure configuration, wherein, The biconical rod includes two circular frustums, and the bottoms of the two circular frustums overlap to form a shape with two small ends and a large middle. This shape reduces the rigidity and strength of the structure on the one hand, avoiding the stress shielding effect of the biological scaffold, and on the other hand On the one hand, when the nutrient solution passes through the protruding part in the middle, a turbulent flow phenomenon is formed, and the material flow speed is fast, which accelerates metabolism.

Further preferably, the diameter of the top surface of the truncated cone is d, the diameter of the bottom surface is D, and for the section between the bottom surface and the top surface, the change of the diameter gradually decreases in a linear or quadratic function.

Further preferably, the unit cell structure forms a derivative configuration of the Diamond structure by adjusting the diameter of the top surface and the diameter of the bottom surface of the biconical bar truncated.

Further preferably, the lattice structure is formed by 3D printing.

According to another aspect of the present invention, there is provided a biomass scaffold formed by arranging the above-mentioned unit cell structures periodically or aperiodically.

Further preferably, the biomass structure is preferably arranged between the bone and the bone tissue, so as to reduce the stiffness at the interface between the bone and the bone tissue.

Further preferably, the application of the biomass structure in human femoral stem, cancellous bone and cortical bone.

Generally speaking, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:

1. The lattice structure of the present invention includes a plurality of unit cells that are uniformly repeated or repeated in gradients, and each unit cell of the lattice structure is formed by connecting multiple biconical rods and nodes between multiple adjacent rods, It can reduce the stiffness and strength of the structure, thereby avoiding the stress shielding effect of the biological scaffold, and promoting the proliferation of osteoblasts in the bone; the protruding volume part of the middle area of the double cone rod, when the nutrient solution passes through, can form a turbulent flow phenomenon and accelerate osteogenesis Cell metabolism and restoration of bone defects;

2. The components of the biological scaffold lattice structure provided by the present invention have good structural mechanical properties and mass transfer properties with natural bones, and have stress consistency with the surrounding bone tissue of the transplanted site, and the coordinated regulation of mechanics and transfer properties The qualitative performance improves the reliability and safety of the implant;

3. Compared with the cylindrical biconical rod provided in the present invention, the reduction and controllability of the top surface diameter makes the mechanical properties of the biconical rod adjustable, and the adjustable bottom diameter makes it The mass transfer performance of the biconical rod can be adjusted;

4. The unit cell structure in the present invention adopts the Diamond configuration. As a lattice structure based on bending deformation, it has mechanical properties close to human bones, and the mechanical properties present orthotropic properties; in addition, the Diamond structure The rods inside the model are oblique rods with an angle of 54.5° with the bottom surface. This lattice structure composed of inclined rods is convenient for 3D printing.

Description of drawings

Fig. 1 is a schematic diagram of a bipyramidal Diamond unit cell constructed according to a preferred embodiment of the present invention;

Fig. 2 is the composition of the Diamond unit cell structure in different viewing directions of the biconical Diamond unit cell constructed according to the preferred embodiment of the present invention;

Fig. 3 is a schematic diagram of different taper bars constructed according to a preferred embodiment of the present invention;

Fig. 4 is the Diamond unit cell schematic diagram of the different tapers constructed according to the preferred embodiment of the present invention;

Fig. 5 is the bioscaffold structure that the bipyramidal Diamond unit cell composition that is constructed according to the preferred embodiment of the present invention obtains;

Fig. 6 is the comparison of the mass transfer permeability of different biconical Diamond bio-stent components constructed according to the preferred embodiment of the present invention;

Fig. 7 is a structural schematic diagram of a biconical rod constructed according to a preferred embodiment of the present invention;

Fig. 8 is a Diamond bioscaffold structure with stress shielding effect constructed according to a preferred embodiment of the present invention.

Throughout the drawings, the same reference numerals are used to designate the same elements or structures, wherein:

1-lattice multicellular structure, 2-unit cell structure, 3-biconical rod, 4-node, 11-traditional homogeneous structure.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

Referring to Fig. 1 to Fig. 5, the unit cell structure 2 provided by the present invention includes a plurality of biconical rods 3, as shown in Fig. 2, respectively in [001], [100] and [010] three Array distribution is carried out in each crystal direction (corresponding to X, Y and Z of the Cartesian coordinate system); on the other hand, a plurality of different topological shapes can also be formed by changing the diameter ratio of d and D in the rod 3 of the unit cell The Diamond unit cell configuration and the corresponding rod unit, in which their diameter ratios are 1/2, 1/3, 1/4, 1/5, 1/6, 1/10, respectively. In the design process of this different topological member, the relative position between members in the original type unit cell does not change, that is, the spatial position of node 4 remains unchanged. However, due to the increasing degree of convexity in the middle of the rod, the structural complexity of the unit cell increases, which improves the mass transfer performance of the support and has higher permeability characteristics; secondly, the position of node 4 is the stress concentration position, and its The reduced volume necessarily reduces the stress intensity and promotes strength matching with the implanted bone.

The multiple unit cell structures 2 are arranged periodically/non-periodically to form a lattice multicellular structure 1, that is, a biomass scaffold.

The biconical Diamond bioscaffold structure of this embodiment and the existing homogeneous rod Diamond bioscaffold structure with the same node spatial position and different rod diameters were tested for flow performance of permeability respectively. Specifically, seven groups of lattice structures were selected for flow performance testing, and the diameter ratios (d/D) of the rods 3 were 1, 1/2, 1/3, 1/4, 1/5, 1/6, 1/10, in detail, the diameter of the homogeneous rod 3 is 0.3mm; the diameter D of the biconical rod 3 is 0.3mm, and the diameters d are 0.15mm, 0.10mm, 0.075mm, 0.06mm, 0.05mm, 0.03 mm. The flow performance simulation test was carried out on the 7 lattice structures of the above 7 groups, and the permeability values obtained after the test are shown in Figure 6. In the figure: the abscissa is the ratio of different diameters, and the ordinate is the permeability. It can be seen from the simulation test results that under the same conditions, the permeability of the lattice structure of this embodiment is greatly improved, and from the view of the flow mass transfer cloud diagram, the lattice structure of the present invention has better flow at the pores. Speed, which means more efficient mass transfer capacity, basically overcomes the low mass transfer capacity of the homogeneous rod Diamond bio-scaffold structure and cannot meet the rapid repair of human bone cells, and can give full play to the mass transfer capacity of the bio-scaffold structure .

As shown in FIG. 7 , on the basis of the above solutions, in some preferred embodiments, the two ends of the biconical rod 3 have the smallest diameter, and the middle part between the two ends has the largest diameter.

Preferably, the diameter of the biconical rod 3 gradually decreases from the middle position to the ends on both sides, forming the largest diameter at the middle position and the smallest diameter at the two ends, that is, the diameter at any position in the middle region The dimensions are larger than the diameter at both ends and smaller than or equal to the diameter in the middle.

The change trend of the rod diameter decreasing from the middle to the end can be linear, quadratic function, etc., and the change trend is based on the requirements of mechanical properties and mass transfer performance. Preferably, the change trend is a linear function.

It should be noted that the diameter of the biconical rod in the present invention gradually changes in diameter in the direction perpendicular to the cross section, and the diameter of the two ends between the rods is smaller than that in the region from the middle to the two ends. diameter of.

In the above-mentioned Diamond unit cells, multiple lattice units 2 are arranged in an array of spatial Cartesian coordinate system, and there is a connection feature between adjacent units, and the connection mode between adjacent units is a common node 4, This periodic array arrangement method is the prior art of the lattice structure, and will not be repeated here.

The above-mentioned unit cell structure and its array method are applied to different biological scaffold parts, such as human femoral stem, cancellous bone and cortical bone.

As shown in Figure 8, a kind of bio-scaffold component comprising the lattice structure of the embodiment, the internal region of the component is a conventional traditional homogeneous structure 11, and the interface between "harder" bone and "softer" bone tissue is adopted Embodiment Biological scaffolds with a lattice structure, because the biconical lattice structure has low stiffness, so a biconical structure is designed between the bone tissue and the bone, which reduces the stiffness of the scaffold at the interface and weakens the stress shielding effect , improving the safety and reliability of the biological scaffold structure.

Preferably, the lattice structure unit cell in this embodiment is selected as a Diamond structure.

In addition, the composition of all biological scaffold components can be completed by 3D printing technology. The main process is as follows:

Design a bioscaffold component model that matches the implantation position, and use Materialize Magics software to discretize into layers, and import the discretized files into the 3D printing device.

3D printing equipment performs layer-by-layer printing processing. After each layer is completed, the substrate is lowered by one layer, and then the printing of the second layer is continued. In this order, layer by layer is superimposed until all discrete layers of the part are printed.

Take out the parts from the substrate, and if necessary, use post-processing such as shot peening and grinding to improve the surface quality of the component and improve the internal structure of the printed material.

In summary, the biconical Diamond structure design adopted in the present invention has the characteristics of continuous diameter change, which increases the complexity of the internal structure, thereby improving the mass transfer capacity of the biological scaffold structure; in addition, because the nodes have smaller The diameter overcomes the common stress shielding effect in biological scaffolds, and can perfectly match the interface physical properties of bone tissue and bone.

Those skilled in the art can easily understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (5)

1. A unit cell structure for biological support, characterized in that, the unit cell structure is connected by a plurality of biconical rods to form a Diamond structure configuration, wherein the biconical rods include two truncated cones, The bottoms of the two circular platforms overlap to form a shape with two small ends and a large middle. On the one hand, this shape reduces the rigidity and strength of the structure and avoids the stress shielding effect of the biological scaffold. On the other hand, when the nutrient solution passes through the protruding part in the middle , forming turbulence phenomenon, the material flow speed is fast, and the metabolism is accelerated. The diameter of the top surface of the circular table is d, the diameter of the bottom surface is D, and d/D is 1/5, 1/6 or 1/10. For the bottom and top surfaces Between the cross-sections, the tendency of the quadratic function of the variation of its diameter decreases gradually. 2. a kind of unit cell structure that is used for biological support as claimed in claim 1, is characterized in that, described unit cell structure forms the derivative structure of Diamond structure by adjusting the top surface diameter and the bottom surface diameter of biconical rod member conical truncated type. 3. A unit cell structure for a biological scaffold as claimed in claim 1, wherein the unit cell structure is formed by 3D printing. 4. A bioscaffold formed by using the unit cell structure according to any one of claims 1-3 in a periodic or non-periodic arrangement. 5. The bioscaffold according to claim 4, wherein the bioscaffold is arranged between the bone and the bone tissue, thereby reducing the stiffness at the interface between the bone and the bone tissue.

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