Cartilage repair scaffold

Abstract

The application relates to a cartilage repair bracket, which comprises subchondral bone and cartilage attached to the subchondral bone, the attachment mode comprising the use of sutures, biocompatible adhesives, porous absorbable polymer layers and / or absorbable fasteners, the subchondral bone comprises a multi-stage porous metal material, and the subchondral bone comprises a first surface and a second surface. The cartilage repair bracket has the advantages of good fusion, stable structure and the like.

Description

Technical Field

[0001] This invention relates to orthopedic implants, specifically a cartilage repair scaffold. Background Technology

[0002] Joint osteochondral defects caused by trauma or bone disease are clinically common, and their incidence has been increasing year by year in recent years due to the growing proportion of middle-aged and elderly people. Articular cartilage itself lacks nerve and blood vessel supply and contains very few cells, making it difficult for it to repair itself after injury. Once cartilage is damaged, it can affect the subchondral bone, leading to osteochondral defects. Due to the different biological characteristics of cartilage and subchondral bone, osteochondral repair is extremely challenging.

[0003] The applicant previously disclosed (CN108201635A) a scaffold for repairing subchondral bone of articular arthritis, wherein the scaffold is composed of a porous salt layer and a porous metal material layer from top to bottom, and the porous metal material layer is a gradient porous metal material layer.

[0004] Although the porous metal material in this patent employs a gradient structure, the gradient is mainly formed by layering through welding or powder sintering. The resulting porous material has interfaces between the gradient pores, failing to achieve true seamless integration. Furthermore, the gradient-distributed porous material prepared above does not achieve a multi-level pore distribution, has low three-dimensional pore connectivity, and its overall performance is still not ideal.

[0005] The applicant also disclosed (CN108201632A) a scaffold for articular cartilage repair, which uses a porous polymer material layer and a porous salt layer to biomimize articular cartilage. Although this polymer scaffold can replace articular cartilage, the most ideal scaffold is still one that uses natural cartilage tissue or cartilage formed by the growth of chondrocytes, and integrates with the body to the greatest extent.

[0006] Existing technologies for preparing scaffolds using natural cartilage suffer from several problems, including insufficient stability between the cartilage and subchondral bone, slow cartilage growth, and a tendency for cartilage dislocation. Subchondral bone is the primary source of blood vessels and nutritional support for cartilage, and high-quality subchondral bone is crucial for improving cartilage growth rate, regenerative capacity, and bonding properties.

[0007] Subchondral bone can be made of porous metal materials, which is conducive to bone tissue ingrowth and fusion. However, existing porous metal materials generally have low strength, insufficient load-bearing capacity, and insufficient permeability.

[0008] Currently, Chongqing Runze Company has independently developed a medical porous tantalum material whose product performance exceeds the international standard (ISO 13782-1996 Surgical implants—Metallic materials—Pure tantalum materials for surgical implants). However, as a medical orthopedic material used in the human body, the product still needs to be continuously improved in order to achieve the most ideal performance.

[0009] The applicant previously disclosed (CN108452385A) a multi-level porous material prepared by cross-weaving two diameters of polymer filaments into a mesh, simultaneously injecting slurry, and then sintering. This material has interconnected channels within its cavity walls and pores on its walls with diameters smaller than the pores enclosed by the cavity walls. The pore structure on the cavity walls is a multi-level porous structure graded according to the material's pore size, with at least two levels. The prepared porous tantalum material has an interconnected pore diameter of 550 μm, and the equivalent diameter of the interconnected channels within the cavity walls is 90 μm. The cavity walls have two levels of pores with diameters smaller than the pores enclosed by the cavity walls. The largest pore has a diameter of 20 μm, and on the cavity walls of the 20 μm pores are even smaller pores, i.e., the smallest level pores, with a diameter of 400 nm. The porous material prepared by this method can achieve rapid and uniform distribution of cells and tissue fluid within the porous material bulk. However, the method of cross-weaving polymer filaments into a web requires a relatively large diameter polymer filament. For small-diameter polymer filaments, the production operation and control of this method are quite difficult. The compressive strength of the multi-level porous material prepared in this patent is about 20 MPa. In order to meet the application of articular cartilage, the preparation process, pore structure, pore size distribution and cavity wall thickness of the multi-level porous material still need further improvement.

[0010] The applicant previously disclosed (CN108452386A) a porous tricalcium phosphate material prepared using polyurethane foam with an edge diameter of 25μm-50μm, achieving a compressive strength of 3.74MPa; and a porous niobium material prepared using polyurethane foam with an edge diameter of 50μm-90μm, achieving a compressive strength of 25.3MPa. The through-pore diameter was 300μm-600μm, the equivalent diameter of the channels penetrating the cavity wall was 40μm-70μm, and the first-order pores on the cavity wall had a diameter of 10μm-20μm. Smaller pores, i.e., minimum-order pores, with a diameter of 400nm-700nm, were also present on the cavity wall surrounding the 10μm-20μm pores. This patent used a foam impregnation method to prepare multi-level porous materials, but the pore structure and pore size distribution were still not sufficiently optimized. The two-level pores on the cavity wall limited the compressive strength, and it could only produce materials with a uniform porosity distribution, failing to adjust and fully simulate the morphology of bone tissue. Summary of the Invention

[0011] The purpose of this invention is to provide a cartilage repair scaffold that has advantages such as high biomimicry, good fusion, and stable structure.

[0012] The technical solution of this invention is as follows:

[0013] A cartilage repair scaffold includes subchondral bone and cartilage attached to the subchondral bone, the attachment method including using sutures, biocompatible adhesives, porous absorbable polymer layers and / or absorbable fasteners, the subchondral bone comprising a multi-level porous metallic material, and the subchondral bone including a first surface and a second surface.

[0014] The cartilage of the present invention can be any type of cartilage that is available or cartilage formed by the growth of chondrocytes; preferably, the cartilage can be cartilage formed in vitro; preferably, the cartilage can be cartilage cultured in a culture medium.

[0015] Preferably, chondrocytes are attached to the first surface of the subchondral bone via a biocompatible adhesive and / or a porous absorbable polymer layer, and the chondrocytes grow into cartilage in vitro. In this way, cartilage forms directly on the subchondral bone with a tight bond.

[0016] The porosity of the second surface of the subchondral bone is greater than that of the first surface. The porosity of the first surface is 20-45%, preferably 30-40%, and the porosity of the second surface is 75-95%, preferably 80-90%.

[0017] The porosity of multi-level porous metallic materials in subchondral bone is preferably distributed in a gradient pattern. This gradient distribution can be a gradient change along one direction or a three-dimensional gradient change. A three-dimensional gradient change refers to a change in multiple directions in three-dimensional space.

[0018] The gradient distribution of the present invention is a fusion structure of interface-free gradient holes.

[0019] The gradient distribution of this invention does not require connection by means of electric welding or other methods.

[0020] The gradient distribution of the present invention is an asymptotic gradient change, a non-asymptotic gradient change, or a combination of asymptotic and non-asymptotic gradient changes.

[0021] Non-gradient porosity refers to a sudden change in porosity, while gradual gradient porosity refers to a continuous change in porosity.

[0022] Optionally, the gradient distribution of the present invention can be a gradual gradient change, a non-gradual gradient change, or a combination of gradual and non-gradual gradient changes in multiple directions in three-dimensional space.

[0023] When the porosity gradient distribution is used, the radial thickness gradient of the cavity wall is preferred.

[0024] Optionally, porous metal materials with non-gradually varying porosity include 2-4 layers of multi-level porous metal structures with different porosities.

[0025] Optionally, in each layer of the porous metallic material with a non-gradually varying porosity, the porosity is either uniformly distributed or combined with a gradual gradient variation.

[0026] Preferably, the subchondral bone is a multi-level progressively porous material, with the porosity gradually increasing from the first surface to the second surface of the subchondral bone.

[0027] In the multi-level gradient porous material of this invention, the pores enclosed by the cavity walls are interconnected open pores. The cavity walls have an axially hollow structure and radial pores. The size of the open pores enclosed by the cavity walls is 50-850 μm, the size of the hollow pores in the cavity walls is 5-90 μm, and the size of the radial pores in the cavity walls is 0.2-15 μm. The distance between the radial pores in the cavity walls is 2-15 μm. The radial thickness of the cavity walls is 50-1000 μm. The first surface roughness of the multi-level gradient porous material is 1-5 μm, and the second surface roughness is 8-22 μm. The outer surface roughness of the cavity walls is 2-10 μm. The radial pores in the cavity walls are single-level pores. "Single-level" is relative to "multi-level," which refers to a specific multi-scale porous structure, while "single-level" means there are no multi-scale pores.

[0028] The axial hollow pores in the cavity wall of the multi-level gradient porous material are continuous internal pores.

[0029] The purity of the multi-gradient porous material of this invention is ≥99%; the mechanical properties of the porous metal material can be adjusted over a wide range by adjusting the process parameters, with a compressive strength of 30-90 (MPa) and an elastic modulus of 1.8-3.8 (GPa).

[0030] This invention improves the diffusion capacity of blood and nutrients in the subchondral bone by adjusting its porosity and pore structure, mimicking the morphology of the host bone tissue. The corresponding mechanical properties and elastic modulus of the subchondral bone match those of the host bone tissue, increasing the growth rate of chondrocytes on the subchondral bone, resulting in good fusion with the host bone and excellent overall performance.

[0031] The metals used in this invention include tantalum, niobium, or their alloys; tantalum is preferred. The subchondral bone is an integral structure.

[0032] The biocompatible adhesive of this invention may include fibrin and / or collagen; it may further include one or more chondrogenic molecules to further promote cartilage formation while firmly adhering to chondrocytes. This invention allows the biocompatible adhesive to be applied to the first surface of the subchondral bone, followed by adhesion of chondrocytes; the cartilage grown from the chondrocytes is less prone to dislocation from the subchondral bone.

[0033] The porous absorbable polymer can be polylactic acid / polyglycolic acid (PLA / PGA). This invention allows for coating or coupling a biocompatible porous absorbable polymer onto the first surface of the subchondral bone to form a biocompatible surface layer onto which chondrocytes can attach, promoting chondrocyte expansion and growth. The porosity of the porous absorbable polymer surface layer is 10-30%, with an average pore size of 1-10 μm.

[0034] Furthermore, a biocompatible adhesive can be first attached to the porous absorbable polymer surface layer, followed by the attachment of chondrocytes.

[0035] In this invention, the absorbable fastener can be a U-shaped nail or a thumbtack made of polylactic acid. The absorbable fastener allows for tight fixation between the cartilage and the subchondral bone.

[0036] Preferably, the first surface of the subchondral bone is processed with pits or grooves to promote chondrocyte attachment.

[0037] Preferably, the pit is hemispherical with a radius of 0.2-0.5 mm; the groove has a depth of 0.1-0.5 mm and a width of 0.5-1.5 mm.

[0038] Preferably, the area of ​​the pits or grooves is 20-60% of the area of ​​the first surface, more preferably 30-50%. Preferably, the pits or grooves are uniformly distributed.

[0039] Preferably, the subchondral bone has internal threads that can mate with a positioning device, the positioning device comprising a biocompatible metal or a biocompatible polymer, and the positioning device having external threads.

[0040] The subchondral bone of the present invention may also contain one or more cartilage-inducing molecules.

[0041] The cartilage-inducing molecules of this invention include growth factors, hydroxyapatite, etc.

[0042] The shape of the stent of the present invention can be cylindrical, wedge-shaped, truncated conical, or other shapes that match the implantation location.

[0043] The preparation method of the multi-level gradient porous material of the present invention is the foam impregnation method.

[0044] Specifically, the double-roller pressing foam impregnation method is adopted.

[0045] Specifically, a multi-level porous metal material with a gradient pore structure was prepared at low cost by using processes such as surface treatment, slurry impregnation, roller pressing, liquid film breaking, cross-linking curing, and three-stage sintering, while controlling the composition and proportion of the raw materials and the operating conditions of the preparation process.

[0046] The porosity distribution of the multi-level porous metal material of this invention is mainly achieved by adjusting the radial thickness distribution of the cavity wall. Specifically, the porosity distribution of the multi-level porous metal material is adjusted by changing the shape of the polymer scaffold and the distance between the rollers during rolling. Preferably, the rollers are arranged in parallel. When preparing a multi-level porous metal material with a progressively increasing porosity gradient, the polymer scaffold can be a structure where the distance between the two opposite sides in contact with the rollers gradually changes. When the distance between the two opposite sides gradually changes along one direction, a multi-level porous metal material with a progressively increasing porosity gradient along one direction can be prepared. When the distance between the two opposite sides gradually changes along multiple directions, a porous metal material with a progressively increasing porosity gradient (three-dimensional progressive gradient) along multiple directions can be prepared. Optionally, the polymer scaffold is a trapezoidal structure with two inclined sides. During rolling, the rollers can contact the two sides of the trapezoid, and through extrusion, the thickness distribution of the metal powder slurry layer on the inner surface of the polymer scaffold changes, thereby changing the thickness distribution of the cavity wall of the finally sintered porous metal material and causing a change in porosity. When preparing porous metal materials with a non-gradual gradient distribution (abrupt change) of porosity, the polymer scaffold can be a structure where the distance between the two opposite sides in contact with the rollers does not change gradually. When the distance between the two opposite sides changes non-gradually in one direction, a hierarchical porous metal material with a non-gradual gradient change in porosity in one direction can be prepared. When the distance between the two opposite sides changes non-gradually in multiple directions, a hierarchical porous metal material with a non-gradual gradient change in porosity in multiple directions (three-dimensional non-gradual gradient change) can be prepared. Optionally, the polymer scaffold can be convex, have multiple stepped shapes on the sides, etc. When preparing porous metal materials combining gradual and non-gradual gradient changes in porosity, the polymer scaffold can be a structure where the distance between the two opposite sides in contact with the rollers simultaneously exhibits both non-gradual and gradual changes. When the distance between the two opposite sides changes gradually and non-gradually in one direction, a hierarchical porous metal material combining gradual and non-gradual gradient changes in porosity in one direction can be prepared. When the distance between two opposite sides exhibits gradual and non-gradual changes, and these changes occur in multiple directions, multi-level porous metal materials combining three-dimensional gradual and non-gradual changes in porosity can be prepared.

[0047] The cartilage repair scaffold prepared by the present invention using the above-mentioned multi-level gradient porous material and cartilage (or chondrocytes) as the main materials has the advantages of high biomimicry, strong ability to integrate with bone tissue, high matching degree, strong bone regeneration ability, high connection stability, not easy to delaminate, not easy to dislocate, and long service life.

[0048] This invention, through the use of metal powders of specific sizes and polymer scaffolds, and precise control of the preparation process, yields a multi-level porous metal material that not only possesses excellent mechanical properties but also exhibits enhanced three-dimensional connectivity and fluid transport capacity due to the presence of axially and radially sized hollow pores in the cavity walls. The porous metal material contains at least two continuous channels: a three-dimensionally interconnected channel enclosed by the cavity walls and axially hollow pores within the cavity walls. When used as a cartilage repair scaffold, the porous metal material's high surface roughness increases the coefficient of friction with the host bone, improving early implantation stability. Furthermore, the porous metal material's strong permeability facilitates the transport of body fluids and nutrient cells within the material, promoting tissue growth and osteoconductivity. Attached Figure Description

[0049] Figure 1 Schematic diagram of a polymer support structure with a tiered platform;

[0050] Figure 2 A schematic diagram of a polymer scaffold with multiple stepped shapes on the side;

[0051] Figure 3 use Figure 2 A schematic diagram of the porosity distribution of a multi-level gradient porous metal material prepared by a polymer scaffold. Detailed Implementation

[0052] The preparation method of the multi-level gradient porous metal material of this invention can be as follows: Metal powder with a particle size of 5-20 μm is mixed with a dispersant aqueous solution and stirred evenly. While stirring, PVA aqueous solution, defoamer, and glyoxal are added sequentially to prepare a metal powder slurry. The polymer scaffold used has an edge diameter of 5-90 μm. After cleaning the surface of the polymer scaffold, it is immersed in the dispersant aqueous solution for surface treatment. After removal and drying, the surface-treated polymer scaffold is immersed in the metal powder slurry. The polymer scaffold is gently squeezed to ensure it fully absorbs the metal powder slurry. Once saturated, the polymer scaffold filled with metal powder slurry is removed and placed in a roller mill for rolling. During rolling, the distance between the rollers remains constant, squeezing out excess metal powder slurry. This process of immersion in slurry and roller rolling is repeated 3-5 times. The preform is then removed, and high-pressure gas is used to blow air onto the surface of the preform to break the surface liquid film. The preform is then left to stand in the air to allow the PVA in the preform to cross-link and solidify. This process allows for control of the pore size of the porous metal material. The metal powder slurry is fully filled into the polymer scaffold through roller extrusion, and excess slurry is removed. The cross-linking and curing process then solidifies the metal powder slurry, preventing agglomeration.

[0053] Then, the green body is placed in a vacuum drying oven to dry at a temperature of 60℃-80℃ for 4-6 hours. After drying, the green body is sintered under vacuum conditions by slowly raising the temperature from room temperature to 580-680℃ at a rate of 2-4℃ / min and holding for 6-8 hours. Then, the temperature is raised slowly to 1300-1600℃ at a rate of 2-4℃ / min and held for 6-8 hours. Then, the temperature is raised to 1800-2100℃ at a rate of 6-8℃ / min and held for 6-8 hours. Finally, the green body is cooled in the furnace.

[0054] For high-melting-point metals such as tantalum and niobium, this invention employs a three-stage sintering method. In the first stage, sintering at 580-680℃, the polymer scaffold, defoamer, and dispersant decompose and are removed through a vacuum system. In the second stage, sintering at 1300-1600℃, the porous metal material is pre-sintered and formed. In the third stage, sintering at 1800-2100℃, the porous metal material undergoes high-temperature sintering to further increase its mechanical strength. The high sintering temperature of this invention is well-matched with the hierarchical porous structure, resulting in porous metal materials with excellent mechanical properties.

[0055] The dispersant used in this invention is stearic acid, polyethylene glycol 400, or chitosan. Adding a dispersant to the metal powder slurry and surface-treating the polymer scaffold with the dispersant can ensure uniform dispersion of the metal powder. Even when using a polymer scaffold with a smaller ridge diameter, agglomeration of the metal powder can still be minimized, resulting in porous metal materials with high mechanical strength.

[0056] This invention, by appropriately controlling the heating rate and sintering temperature, creates continuous through-holes inside the cavity wall and pores of suitable diameter in the radial direction of the cavity wall, thereby increasing the mass transfer capacity.

[0057] The defoamer used in this invention is an organosilicon defoamer, preferably a trimethylsiloxy-terminated polydimethylsiloxane.

[0058] In one embodiment, the multi-level gradient porous metal material prepared by the present invention has a gradually changing porosity. The metal is tantalum. The porosity of one surface is 35%, the size of the openings enclosed by the cavity walls is 50-60 μm, the size of the hollow pores in the cavity walls is about 6 μm, the size of the radial pores in the cavity walls is 0.5-2 μm, the distance between the radial pores in the cavity walls is 2-5 μm, the radial thickness of the cavity walls is about 200 μm, the surface roughness is 2-5 μm, and the roughness of the outer surface of the cavity walls is 2-5 μm. The porosity of the opposite surface is 95%, the size of the openings enclosed by the cavity walls is 150-780 μm, the size of the hollow pores in the cavity walls is about 6 μm, the size of the radial pores in the cavity walls is 0.5-2 μm, the distance between the radial pores in the cavity walls is 2-5 μm, the radial thickness of the cavity walls is about 100 μm, the surface roughness is 15-20 μm, and the roughness of the outer surface of the cavity walls is 2-5 μm. In one embodiment, the porosity of the multi-level gradient porous metal material prepared by the present invention is a non-gradual gradient change. The metal is niobium. The multi-level gradient porous metal material is divided into an upper half and a lower half. The upper half provides a first surface with a porosity of 30%, and the lower half provides a second surface with a porosity of 70%. The length ratio of the upper half to the lower half is 1:1.5.

[0059] In one embodiment, the porosity of the multi-level gradient porous metal material prepared by the present invention is a non-gradual gradient change. The metal is a tantalum-niobium alloy. The multi-level gradient porous metal material is divided into an upper part and a lower part. The upper part provides a first surface with a porosity of 25%, and the lower part provides a second surface with a porosity of 90%. The length ratio of the upper part to the lower part is 1:3.

[0060] In one embodiment, the porosity of the multi-level gradient porous metal material prepared by the present invention changes non-gradually, and the polyurethane polymer scaffold has multiple stepped shapes on its sides, as shown in the schematic diagram. Figure 2 As shown. During rolling, the two sides of the roller contact support result in porous metal with a non-gradual porosity distribution. After the upper surface is cut into a regular shape along the longitudinal direction with flush edges, the porosity distribution is shown in the schematic diagram. Figure 3 As shown.

[0061] In one embodiment, the porosity of the multi-level gradient porous metal material prepared by the present invention is a non-gradual gradient change. The metal is tantalum. The multi-level gradient porous metal material is divided into an upper part, a middle part, and a lower part. The upper part provides a first surface with a porosity of 20-40%, the middle part has a porosity of 45-60%, and the lower part provides a second surface with a porosity of 75-90%. The length ratio of the upper, middle, and lower parts is 1:1.5 to 2:2.5 to 3.

[0062] In one embodiment, the first surface of the subchondral bone is machined with a pit, which is hemispherical with a radius of 0.3 mm.

[0063] In one embodiment, the first surface of the subchondral bone is machined with a groove having a depth of 0.4 mm and a width of 0.5 mm.

Claims

1. A cartilage repair scaffold, characterized in that: The device includes subchondral bone and cartilage attached to the subchondral bone. Attachment methods include using sutures, biocompatible adhesives, porous absorbable polymer layers, and / or absorbable fasteners. The subchondral bone comprises a multi-level porous metal material, including a first surface and a second surface. In the multi-level porous metal material, the pores enclosed by the cavity walls are interconnected open pores, the cavity walls are axially hollow, and the cavity walls have radial pores. The porosity of the multi-level porous metal material in the subchondral bone is gradient-distributed; the porosity gradient distribution is a radial thickness gradient change of the cavity walls. The multi-level porous metal material is prepared by the following method: Metal powder with a particle size of 5-20 μm is mixed with a dispersant aqueous solution and stirred until homogeneous. While stirring, PVA aqueous solution, defoamer, and glyoxal are added sequentially to prepare a metal powder slurry. A polymer scaffold with an edge diameter of 5-90 μm is used. After cleaning the surface of the polymer scaffold, it is immersed in the dispersant aqueous solution for surface treatment. The polymer scaffold is then removed and dried. After drying, the surface-treated polymer scaffold is immersed in the metal powder slurry, and the polymer scaffold is gently squeezed to ensure it fully absorbs the metal powder slurry. Once saturated, the slurry-filled material is removed from the slurry. The polymer scaffold is removed and then placed into a roller mill for pressing. During the pressing process, the distance between the rollers remains constant, extruding excess metal powder slurry. This process of impregnating with slurry and pressing with rollers is repeated 3-5 times. The preform is then removed, and high-pressure gas is used to blow air onto the surface of the preform to break the surface liquid film. It is then left to stand in the air to allow the PVA in the preform to cross-link and solidify. This process controls the porosity of the porous metal material. The roller extrusion process ensures that the metal powder slurry is fully filled inside the polymer scaffold and removes excess slurry. The cross-linking and solidification process solidifies the metal powder slurry, preventing agglomeration. Then, the green body is placed in a vacuum drying oven for drying at a temperature of 60℃-80℃ for 4-6 hours. After drying, the green body is sintered under vacuum conditions at a heating rate of 2-4℃ / min from room temperature to 580-680℃ and held for 6-8 hours. Then, the heating rate is increased to 1300-1600℃ at a heating rate of 2-4℃ / min and held for 6-8 hours. Then, the heating rate is increased to 1800-2100℃ at a heating rate of 6-8℃ / min and held for 6-8 hours. Finally, the green body is cooled in the furnace.

2. The cartilage repair scaffold according to claim 1, characterized in that: Cartilage refers to cartilage cultured in a culture medium.

3. The cartilage repair scaffold according to claim 1, characterized in that: Chondrocytes are attached to the first surface of subchondral bone using a biocompatible adhesive and / or a porous absorbable polymer layer, and the chondrocytes grow into cartilage in vitro.

4. The cartilage repair scaffold according to claim 1, characterized in that: The porosity of the second surface is greater than that of the first surface.

5. The cartilage repair scaffold according to claim 1, characterized in that: The porosity of the first surface is 20-45%, and the porosity of the second surface is 75-95%.

6. The cartilage repair scaffold according to claim 1, characterized in that: Metals include tantalum, niobium, or their alloys; Subchondral bone is an integral structure.

7. The cartilage repair scaffold according to claim 1, characterized in that: Biocompatible adhesives include fibrin and / or collagen; porous absorbable polymers are polylactic acid / polyglycolic acid; absorbable fasteners are U-shaped nails or thumbtacks made of polylactic acid.

8. The cartilage repair scaffold according to claim 1, characterized in that: The first surface of the subchondral bone is machined with pits or grooves.

9. The cartilage repair scaffold according to claim 8, characterized in that: The pit is hemispherical with a radius of 0.2-0.5 mm; The depth of the trench is 0.1-0.5mm and the width is 0.5-1.5mm.

10. The cartilage repair scaffold according to claim 1, characterized in that: The subchondral bone has internal threads that can be used with positioning devices.

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