Degradable knee cavity repair stent and preparation method thereof

Abstract

The application discloses a degradable knee joint cavity repairing support and a preparation method thereof, and is used for anastomosis repair of ruptured ligament and tendon in a knee joint cavity. The support is a whole integrated coaxial hollow tubular structure, comprising two suture tubes arranged symmetrically left and right, and a contraction tube integrally connected between the two suture tubes. The application provides a degradable knee joint cavity repairing support and a preparation method thereof, and has a self-adaptive mechanical correction function, and can radically cure postoperative tendon relaxation defects. The application innovatively designs a three-section coaxial tubular structure, and relies on controllable degradation contraction characteristics of the material of the middle contraction tube to continuously output uniform and stable axial contraction tension in a key tendon healing period, actively corrects the tendon which is postoperative compensation hyperplasia, lengthened and relaxed to the middle part, and solves problems of insufficient ligament tension, knee joint shaking, forcelessness and the like after traditional tendon suture from the root, and greatly improves ligament repair precision and postoperative joint stability.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials technology, and in particular to a biodegradable intra-articular repair scaffold for the knee joint and its preparation method. Background Technology

[0002] Intra-articular repair is a minimally invasive repair method for soft tissue injuries such as tendons and ligaments within the knee joint cavity. It involves connecting, fixing, and reinforcing the damaged tissue within the original space of the joint cavity. Utilizing a repair carrier adapted to the cavity's morphology, it conforms to the physiological structure of the body's own tissues to achieve wound repair, eliminating the need for extensive dissection of surrounding tissues. This reduces trauma to the body, promotes natural fusion and regeneration of damaged tissues, and restores normal joint biomechanical function and stability.

[0003] Anterior cruciate ligament rupture of the knee joint is a common sports injury. The mainstream repair method is arthroscopic tendon suturing and ligament reconstruction surgery, which achieves ligament structural repositioning and functional restoration by suturing and fixing the two ends of the ruptured tendon.

[0004] However, during the actual implementation process, the applicant discovered the following problems with the patent: In practical applications, conventional tendon sutures rely solely on sutures for fixation, which can easily lead to tendon hyperplasia and laxity, causing joint instability, abnormal movement, and increasing the risk of injury recurrence. Furthermore, existing rigid supports are difficult to fuse, easily causing rejection and resulting in poor healing effects. Existing connecting devices have poor structural adaptability, lack tension adjustment function, and are mostly non-degradable, requiring a second surgery. Currently, there is a lack of dedicated repair stents that can be fused, adaptively adjust tension, and are completely degradable.

[0005] Therefore, it is necessary to propose a biodegradable intra-articular repair scaffold for the knee joint and its preparation method, so as to provide a new technical solution to solve the above-mentioned technical problems. Summary of the Invention

[0006] Therefore, it is necessary to provide a biodegradable intra-articular knee joint repair scaffold and its preparation method to address the above-mentioned technical problems, in order to solve the technical problems of tendon hyperplasia and elongation, laxity and weakness, inability to auto-fusion, non-degradable scaffold, and inconvenient intraoperative suturing after existing knee joint ligament and tendon repair surgery, and to provide a biodegradable intra-articular knee joint repair scaffold and its preparation method.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A biodegradable intra-articular repair stent for the knee joint, which is applied to biomedical materials.

[0008] The biodegradable intra-articular repair stent of the knee joint specifically includes a protective plate for anastomosing and repairing ruptured ligaments and tendons within the knee joint cavity. The stent is an integral coaxial hollow tubular structure, including two symmetrically arranged suture tubes and an integrally connected shrink tube between the two suture tubes. The two suture tubes and the shrink tube are hollow and coaxially arranged. Both the suture tube and the shrink tube are made of biodegradable biomedical composite material that can penetrate and fuse with the body's own tendons.

[0009] As a preferred embodiment of the biodegradable intra-articular repair stent of the knee joint provided by the present invention, the suture tube has multiple sets of through-hole suture fixation holes evenly arrayed on its wall, the suture fixation holes having a diameter of 0.3-0.5mm and a spacing of 1-1.5mm.

[0010] As a preferred embodiment of the biodegradable intra-articular repair stent for the knee joint provided by the present invention, the suture tube and the shrink tube are designed with differentiated structural parameters and porosity. The wall thickness of the suture tube is smaller than that of the shrink tube, the porosity of the suture tube is 60%-70%, and the porosity of the shrink tube section is 40%-50%. The shrink tube has a denser and tougher structure than the suture tube section, and its degradation rate is slower than that of the suture tube.

[0011] As a preferred embodiment of the biodegradable intra-articular repair stent for the knee joint provided by the present invention, the suture tube is made of a highly fusion-compatible composite material, with collagen and hyaluronic acid as the main functional modified components. The shrink tube is made of a high-toughness shrinkable composite material, with PLGA as the main matrix component.

[0012] As a preferred embodiment of the biodegradable intra-articular repair stent of the knee joint provided by the present invention, the stent adopts a flexible tubular structure design, and the overall texture is flexible and deformable. The stent has fluid tolerance and is not prone to swelling, deformation, cracking and structural collapse in the knee joint fluid infiltration environment.

[0013] As a preferred embodiment of the biodegradable intra-articular repair stent of the knee joint provided by the present invention, the shrink tube has stable adaptive axial shrinkage characteristics and can continuously generate uniform and stable axial shrinkage force during the slow degradation of the material.

[0014] As a preferred embodiment of the biodegradable intra-articular repair stent provided by the present invention, the stent can gradually complete the all-round degradation as the tendon tissue heals.

[0015] A preferred embodiment of a method for preparing a biodegradable intra-articular repair stent for the knee joint.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a biodegradable intra-articular knee joint repair stent with adaptive mechanical correction function, which can cure postoperative tendon laxity defects. The invention innovatively designs a three-segment coaxial tubular structure. Relying on the controllable degradation and contraction characteristics of the material of the middle contraction tube, it can continuously output uniform and stable axial contraction force during the critical healing period of tendon of 2-6 months. It actively and precisely tightens and corrects the postoperative compensatory hyperplasia, lengthening and laxity of tendon towards the middle, fundamentally solving the problems of insufficient ligament tension, knee joint wobbling and weak force after traditional tendon suture, and greatly improving the accuracy of ligament repair and postoperative joint stability.

[0017] This invention provides a biodegradable intra-articular repair stent for the knee joint, which is convenient and efficient to operate at medium speed and is suitable for minimally invasive clinical surgical scenarios. The invention has evenly distributed precision suture holes at both ends of the suture tube. Compared with the traditional non-porous tubular repair structure, it can quickly complete suture threading and tendon alignment and fixation, which greatly reduces the operation difficulty of arthroscopic minimally invasive surgery, shortens the operation time, reduces intraoperative tissue trauma, and meets the needs of clinical batch minimally invasive repair surgery. It is highly practical.

[0018] This invention provides a method for preparing a biodegradable intra-articular repair scaffold for the knee joint. The structure and process are innovative and adapted to clinical needs. The structure of this invention focuses on postoperative tendon correction and tissue fusion. Through material formulation and one-piece molding process, the degradation rate, contraction tension and fusion speed of the scaffold can be precisely controlled. It is suitable for knee ligament repair surgery of different age groups and different degrees of injury, with wide clinical applicability and strong practicality. Attached Figure Description

[0019] To more clearly illustrate the solutions in this invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of a biodegradable intra-articular repair stent for the knee joint provided by the present invention; Figure 2 This is a schematic cross-sectional view of the AA section of a biodegradable intra-articular repair stent for the knee joint provided by the present invention. Figure 3 This invention provides a flowchart of the preparation process of biodegradable functional composite materials in a method for preparing a biodegradable intra-articular repair stent for the knee joint. Figure 4The flowchart illustrates the preparation process of a three-section hollow stent tube for a biodegradable intra-articular repair stent provided by this invention.

[0021] The markings in the diagram are explained as follows: 1. Support; 2. Shrink tube; 3. Suture tube; 4. Suture fixation hole. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present invention, 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0023] This invention provides a biodegradable intra-articular repair stent for the knee joint and its preparation method.

[0024] For details, please refer to Figure 1 , Figure 2 A biodegradable intra-articular repair stent and its preparation method specifically include anastomosis repair of ruptured ligaments and tendons in the intra-articular cavity of the knee joint. The stent (1) is an integral coaxial hollow tubular structure, including two suture tubes (3) arranged symmetrically on the left and right, and a shrink tube (2) integrally connected between the two suture tubes (3). The two suture tubes (3) and the shrink tube (2) are hollow and coaxially arranged. Both the suture tube (3) and the shrink tube (2) are made of biomedical composite materials that are biodegradable and can be integrated with autologous tendons.

[0025] This invention provides a biodegradable intra-articular repair stent for the knee joint, which has an adaptive mechanical correction function and can cure postoperative tendon laxity defects. This invention innovatively designs a three-segment coaxial tubular structure. Relying on the controllable degradation and contraction characteristics of the material of the middle contraction tube (2), it can continuously output uniform and stable axial contraction force during the critical healing period of the tendon of 2-6 months. It actively tightens and corrects the postoperative compensatory hyperplasia, lengthening and laxity of the tendon towards the middle, and solves the problems of insufficient ligament tension, knee joint wobbling and weak force after traditional tendon suture from the root, greatly improving the accuracy of ligament repair and postoperative joint stability.

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0027] Example 1: Please refer to Figures 1-2A biodegradable intra-articular repair stent for the knee joint is provided in this embodiment. The stent is a coaxial hollow cylindrical tube with a total length adapted to the conventional size for repairing cruciate ligament injuries of the knee joint and an inner diameter adapted to the size of human tendon insertion. The stent 1 consists of symmetrical suture tubes 3 on the left and right sides and an integrated shrink tube 2 in the middle. The three sections are seamlessly connected and hollow inside.

[0028] The suture tube 3 has evenly distributed circular suture holes 4 on its walls, with a diameter of 0.3-0.5 mm and a spacing of 1-1.5 mm, facilitating the rapid passage of surgical sutures during surgery. This allows for tight binding and fixation of the support 1 to the proximal and distal ends of the ruptured tendon. The suture tube 3 uses a high-porosity formula with a porosity of 60%-70%, which allows for rapid absorption of tissue fluid and adhesion of tendon cells after implantation, achieving rapid fusion with the autologous tendon. The middle contraction tube 2 has a thicker wall than the suture tube 3, a porosity of 40%-50%, and a stronger structural toughness. Its degradation cycle is longer than that of the suture tube 3. After implantation, the suture tube gradually completes tissue fusion and slowly degrades within one to three months, firmly fixing the tendons on both sides. The contraction tube segment continuously maintains structural integrity and continuously generates uniform axial contraction force during the critical tendon healing period of 2-6 months. It gradually stretches and tightens the loose tendon, corrects tendon lengthening defects, and maintains normal ligament tension. After the tendon is fully healed and matured, the contraction tube segment gradually and completely degrades and is absorbed.

[0029] Example 2: Please refer to Figures 3-4 A method for preparing a biodegradable intra-articular repair scaffold for the knee joint: S1. Preparation of biodegradable composite substrate: By weight, take 60-70 parts of PLGA, 15-20 parts of chitosan, 8-12 parts of collagen, and 3-5 parts of hyaluronic acid. After mixing, add 0.5-1 parts of bio-crosslinking agent and a trace amount of tendon fusion promoting factor. Place in a low-temperature constant temperature stirring tank and stir at low speed at 30-40℃ for 2-3 hours. Combine with ultrasonic dispersion for 30 minutes to ensure uniform mixing of raw materials. Then, vacuum degassing was performed for 40 minutes to remove air bubbles from the slurry, resulting in a uniform, fine, and impurity-free composite slurry. Among them, the suture section slurry increases the ratio of collagen and hyaluronic acid to improve fusion performance; the shrinkage section slurry increases the PLGA ratio to improve structural toughness and long-term shrinkage degradation performance.

[0030] S2. Integrated injection molding: A three-section coaxial precision mold is used to inject two different ratios of composite slurry into the corresponding areas of the mold. Low temperature and low pressure injection molding ensures that the coaxiality error of the three sections is ≤0.02mm, and the internal hollow channels are smooth and unobstructed. After molding, a complete tubular support blank is obtained.

[0031] S3. Post-processing modification: Using a precision laser drilling device, uniform suture holes are processed on the suture tube sections at both ends. The molded scaffold is placed in a low-temperature vacuum environment for 24 hours for shaping, followed by aseptic freeze-drying to remove residual moisture. Finally, plasma surface hydrophilic modification is performed to improve the scaffold cell adhesion and tissue fusion ability.

[0032] S4. Sterilization and Packaging: The modified scaffold is sterilized with ethylene oxide and vacuum-sealed in a sterile environment to obtain the finished biodegradable intra-articular repair scaffold based on the above structural design.

[0033] Example 2: The method for preparing a biodegradable intra-articular repair scaffold provided in Example 2 has been further optimized, specifically, as follows: Figure 3 , Figure 4 As shown, this embodiment addresses the repair scenario of severe cruciate ligament tears, high postoperative laxity risk, and high patient activity demands. It optimizes the ratio of the two-component slurry and the preparation process parameters to improve the mechanical strength and long-term tensile stability of the contractile segment, while retaining the rapid tissue fusion performance of the suture segment. This creates a gradient fit with Embodiment 2, covering clinical needs of different injury degrees. The specific preparation steps are as follows: S1. Precise preparation of highly stable differentiated two-component composite slurry: Two sets of functional slurries are prepared according to the mass ratio to meet the needs of severe damage repair; High-fusion slurry for suture segments: PLGA 55 parts, chitosan 18 parts, collagen 18 parts, hyaluronic acid 8 parts, bio-crosslinking agent 0.8 parts, and trace amounts of tendon fusion-promoting factor. This significantly increases the proportion of collagen and hyaluronic acid, further accelerating cell adhesion and tissue fusion, making it suitable for tendon healing scenarios with large wounds. High-stability shrinkage slurry for shrinkage sections: 78 parts PLGA, 12 parts chitosan, 6 parts collagen, 2 parts hyaluronic acid, and 1.2 parts bio-crosslinking agent. Increasing the proportion of PLGA matrix and the amount of crosslinking agent enhances the crosslinking density of the material, improves the overall structural toughness and fatigue resistance of the scaffold, and extends the effective mechanical maintenance cycle. After preparation, the mixture is placed in a 35℃ constant temperature mixing tank and stirred at low speed for 3 hours, ultrasonically dispersed for 40 minutes, and vacuum degassed for 50 minutes to completely eliminate air bubbles inside the slurry and ensure the homogeneity and stability of the slurry.

[0034] S2. High-precision differentiated integrated injection molding: Using the same three-section coaxial precision mold, the mold temperature is strictly controlled at 28℃ and the injection pressure is 0.3MPa, which is lower than the injection pressure of the basic embodiment. This avoids stress residue in the high solids content slurry. Two sets of differentiated slurries are precisely injected in sections to form a three-section hollow tubular support in one piece. The coaxiality error is strictly controlled to ≤0.02mm. The molding wall thickness parameters are optimized. The wall thickness of the stitched tube section is 0.25mm and the porosity is 65%. The wall thickness of the shrink tube section is 0.45mm and the porosity is 42%. Compared with the basic embodiment, the density of the shrink tube section structure is further improved, ensuring long-term stable shrinkage performance.

[0035] S3, Enhanced post-processing modification technology: Using laser precision drilling technology, uniform suture holes with a diameter of 0.4mm and a spacing of 1.2mm are processed in the suture tube segment, taking into account both suture strength and tissue fusion area; Extend the low-temperature vacuum setting time to 30 hours to completely eliminate the internal stress of the support during molding and avoid subsequent deformation failure; The aseptic freeze-drying time was adjusted to 12 hours to retain the material activity to the greatest extent. The duration of plasma surface modification treatment is increased to enhance the hydrophilicity and cell adhesion properties of the scaffold surface, thus meeting the need for rapid healing of severely injured tendons.

[0036] S4. Aseptic Sterilization and Graded Packaging: Low-temperature ethylene oxide sterilization process is adopted to avoid the risk of failure of highly active materials. The sterilization time is appropriately extended to ensure the medical sterility level.

Claims

1. A biodegradable intra-articular repair stent for the knee joint, used for the anastomosis and repair of ruptured ligaments and tendons within the knee joint cavity, characterized in that: The support (1) is an integral coaxial hollow tubular structure, including two suture tubes (3) arranged symmetrically on the left and right, and a shrink tube (2) integrally connected between the two suture tubes (3). The two suture tubes (3) and the shrink tube (2) are hollow and coaxially arranged. Both the suture tube (3) and the shrink tube (2) are made of biomedical composite materials that are biodegradable and can be integrated with autologous tendons.

2. The biodegradable intra-articular repair stent of the knee joint according to claim 1, characterized in that, The suture tube (3) has multiple sets of through-hole suture fixing holes (4) evenly arranged on its tube wall. The diameter of the suture fixing holes (4) is 0.3-0.5 mm and the spacing between the holes is 1-1.5 mm.

3. The biodegradable intra-articular repair stent of the knee joint according to claim 2, characterized in that, The suture tube (3) and the shrink tube (2) are designed with differentiated structural parameters and porosity. The wall thickness of the suture tube (3) is smaller than that of the shrink tube (2). The porosity of the suture tube (3) is 60%-70%, and the porosity of the shrink tube section (2) is 40%-50%. The shrink tube (2) has a denser structure and higher structural toughness than the suture tube segment, and its degradation rate is slower than that of the suture tube (3).

4. The biodegradable intra-articular repair stent of the knee joint according to claim 3, characterized in that, The suture tube (3) is made of a highly fusion-compatible composite material with collagen and hyaluronic acid as the main functional modification components; The shrink tube (2) is made of a high-toughness shrinkable composite material with PLGA as the main matrix component.

5. A biodegradable intra-articular repair stent for the knee joint according to claim 4, characterized in that, The stent (1) adopts a flexible tubular structure design and is flexible and deformable. The stent (1) has fluid tolerance and is not prone to swelling, deformation, cracking and structural collapse in the knee joint fluid immersion environment.

6. The biodegradable intra-articular repair stent of the knee joint according to claim 1, characterized in that, The shrink tube (2) has stable adaptive axial shrinkage characteristics and can continuously generate uniform and stable axial shrinkage force during the slow degradation of the material.

7. The biodegradable intra-articular repair stent of the knee joint according to claim 1, characterized in that, The scaffold (1) can be gradually degraded in all directions as the tendon tissue heals.

8. A method for preparing a biodegradable intra-articular repair stent for the knee joint, used to prepare the biodegradable intra-articular repair stent for the knee joint as described in any one of claims 1-7, characterized in that: Includes the following steps: S1. Preparation of differentiated biodegradable composite slurry: Using PLGA, chitosan, collagen and hyaluronic acid as core raw materials, combined with bio-crosslinking agents and tendon fusion promoting factors, composite slurries suitable for suture segments and composite slurries suitable for shrinkage segments are prepared respectively. S2. Three-section integrated injection molding: Using a high-precision coaxial three-section mold, two different composite slurries are injected in sections, and low-temperature and low-pressure integrated injection molding is performed to obtain a tubular support blank with three coaxial sections, hollow and through, and regular structure. S3. Precision drilling and modification: Laser precision drilling is performed on the two end suture tube segments to form a uniform array of suture holes; The scaffold undergoes a series of processes, including low-temperature vacuum shaping, aseptic freeze-drying, and plasma surface hydrophilic modification, to eliminate internal stress during molding and improve tissue adhesion and cell adhesion. S4. Sterilization and Packaging: Low-temperature ethylene oxide sterilization is used, followed by vacuum packaging in a sterile environment to obtain a finished biodegradable intra-articular repair stent for the knee joint. Among them, by adjusting the mass ratio of each raw material, the molding wall thickness, porosity and process parameters, the degradation cycle, tissue fusion speed and axial shrinkage tension of the suture tube segment and shrinkage tube segment can be differentially controlled.

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