Novel 3D printing bone fracture plate

Abstract

The invention provides a novel 3D printing bone fracture plate, and belongs to the technical field of medical instruments. The bone fracture plate is manufactured by adopting an additive manufacturing process and has a local reinforcing structure design aiming at a reinforcing area, and a 3D printing strategy of layer-by-layer energy density gradient change is adopted; the density and the mechanical property of a key part are remarkably improved, so that the compression resistance and the shear resistance of the bone fracture plate in a local area are greatly enhanced, the accurate matching with the bone of a patient is ensured, and the stability in the fracture healing process is favorably promoted; the design process based on the CT / MRI data of the patient ensures that the bone fracture plate can be produced in a customized mode according to individual differences, and the success rate of an operation and the recovery speed of the patient are increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical devices, and particularly relates to a novel 3D printed bone plate. Background Art

[0002] With the development of additive manufacturing, also known as 3D printing technology, new solutions have been provided for the field of medical devices, especially personalized medical products. 3D printing technology can customize the production of bone plates according to the CT or MRI image data of patients, so as to achieve a high degree of matching with the patient's bones and improve the treatment effect. In addition, by adjusting the printing parameters, local enhancement can be achieved in specific areas to enhance the mechanical properties of the bone plate, such as compressive and shear resistance, while optimizing the overall weight and rigidity, and reducing the negative impact caused by the mismatch with the elastic modulus of the human bone.

[0003] For patients undergoing distraction osteotomy surgery, after the bone plate is installed, there are often large blank areas in the distraction area, forming high-stress areas of the bone plate. And to fill these blanks, some doctors will choose to take bone from the patient's ilium for filling, while others choose not to perform any filling. Not filling may increase the risk of bone plate fracture, while taking bone from the ilium may cause damage to the bones in the healthy area of the patient. Summary of the Invention

[0004] The purpose of the present invention is to provide a novel 3D printed bone plate, aiming to solve the problem in the prior art that for patients undergoing distraction osteotomy surgery, after the bone plate is installed, there are often large blank areas in the distraction area, forming high-stress areas of the bone plate. And to fill these blanks, some doctors will choose to take bone from the patient's ilium for filling, while others choose not to perform any filling. Not filling may increase the risk of bone plate fracture, while taking bone from the ilium may cause damage to the bones in the healthy area of the patient.

[0005] To achieve the above purpose, the present invention provides the following technical solutions: A novel 3D printed bone plate, comprising: A bone plate, which is made by an additive manufacturing process and has a local enhancement structure design for the enhanced area. Through a 3D printing strategy with a gradient change in energy density layer by layer, the density is increased at key positions to form a gradient material structure, significantly enhancing the local compressive and shear resistance; Screw holes, which are opened on the surface of the bone plate; The local enhancement structure design includes an energy input strategy in the enhanced area. By adjusting the laser power, scanning speed, and layer thickness, the energy density is increased layer by layer in the enhanced area to form a density gradient; The enhanced region was fabricated into TC4-high material by laser melting of TC4 titanium alloy powder with a laser power of 300 - 400 W, a scanning speed of 800 - 1000 mm / s, and a layer thickness of 20 - 30 μm through 3D printing; The non-enhanced region was fabricated into TC4-low material by laser melting of TC4 titanium alloy powder with a laser power of 200 - 300 W, a scanning speed of 1100 - 1200 mm / s, and a layer thickness of 40 - 50 μm through 3D printing.

[0006] As a preferred embodiment of the present invention, the local enhanced structure design includes an energy input strategy in the enhanced region, where the energy density is gradually increased layer by layer in the enhanced region by adjusting the laser power, scanning speed, and layer thickness to form a density gradient.

[0007] As a preferred embodiment of the present invention, in the additive manufacturing, the printing parameters used in the enhanced region are controlled as a laser power of 300 - 400 W, a scanning speed of 800 - 1000 mm / s, and a layer thickness of 20 - 30 μm, and the printing parameters used in the non-enhanced region are controlled as a laser power of 200 - 300 W, a scanning speed of 1100 - 1200 mm / s, and a layer thickness of 40 - 50 μm.

[0008] As a preferred embodiment of the present invention, the design of the bone plate is based on the DICOM file generated from the patient's CT / MRI data. The shape after bone correction is simulated through 3D modeling software, and the position and angle of the enhanced region are planned to ensure precise matching with the patient's bone.

[0009] As a preferred embodiment of the present invention, the mechanical properties of the local enhanced region and the surrounding materials transition smoothly, avoiding stress concentration caused by sudden changes in rigidity. At the same time, the overall weight and rigidity are reduced, and the stress shielding effect caused by the mismatch of the elastic modulus with the human bone is reduced.

[0010] Compared with the prior art, the beneficial effects of the present invention are: 1. By adopting the additive manufacturing process and implementing the local enhanced structure design, especially applying the 3D printing strategy with a gradually changing energy density layer by layer in the enhanced region, the density and mechanical properties of the key parts are significantly improved in this new type of 3D printed bone plate. The compressive and shear resistance capabilities in the local region of the bone plate are enhanced, and precise matching with the patient's bone is ensured, which is beneficial to promoting the stability during the fracture healing process. Stress buffering characteristics: In the high-stress area of the local enhanced bone plate, the TC4-high material with a high elastic modulus is used at the osteotomy distraction site to provide rigid support to resist instantaneous impact loads and peak stresses during walking; the TC4-low material with a low elastic modulus is used in the fitting area to allow moderate elastic deformation to absorb the energy of cyclic loads.

[0011] 2. The local reinforcement structure of the bone plate achieves a smooth transition of mechanical properties with the surrounding materials, effectively avoiding the stress concentration problem caused by the sudden change of rigidity, and reducing the risk of complications that may occur during long-term use. At the same time, this design reduces the weight and rigidity of the overall device, which helps to reduce the stress shielding effect caused by the mismatch with the elastic modulus of the natural human bone, thereby promoting the normal growth and reconstruction of the bone. By optimizing the printing parameter control, it not only meets the needs of local reinforcement, but also takes into account the lightweight of the overall structure, making the bone plate more in line with the requirements of biocompatibility and providing better support for the patient's rehabilitation.

[0012] 3. Improved biomechanical compatibility: The gradient transition of the elastic modulus between the high stress area and the fitting area makes the overall modulus of the plate closer to the mechanical matching range of the cortical bone and the cancellous bone, the stress distribution is more uniform, and the elastic modulus of the fitting area is better matched with the bone, which effectively reduces the risk of stress shielding and accelerates the bone integration process.

[0013] 4. Optimized design of locally reinforced plates: This process uses precise gradient design and dynamic adaptability optimization strategies. The plates in high-stress areas are reinforced at the bone distraction sites to significantly improve the material's load-bearing performance. The non-reinforced process is retained in the fitting area to reduce the stress shielding effect. The locally reinforced plates perform best in core biomechanical indicators such as uniformity of stress distribution and bone surface adaptability. The elastic modulus has a gradient transition, and the low elastic modulus material allows moderate elastic deformation to absorb cyclic load energy, which can effectively meet the clinical needs of complex fracture surgery. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are used to provide an understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 It is a main perspective view of the present invention; Figure 2 This is a loading diagram of the bone plate in the present invention; Figure 3 It is a curve diagram for verifying the convergence of the equivalent elastic strain of the matching metal bone plate in the present invention; Figure 4 This is a graph showing the convergence verification results of the equivalent elastic strain and its percentage change in the present invention; Figure 5 It is a schematic diagram of the constraints and load loading in the present invention; Figure 6 is a material parameter diagram in the present invention; Figure 7 It is the mechanical test design drawing of the metal bone plate in the present invention; Figure 8 It is a comparison diagram of equivalent elastic strain in the present invention; Figure 9 It is the equivalent elastic strain analysis result diagram in the present invention; Figure 10 It is the equivalent stress comparison diagram in the present invention; Figure 11 It is the equivalent stress analysis result diagram in the present invention; Figure 12 It is the dynamic cantilever test result diagram in the present invention; Figure 13 It is the dynamic cantilever cyclic test curve diagram in the present invention; Figure 14 It is the static cantilever test result diagram in the present invention; Figure 15 It is the static cantilever test curve diagram in the present invention; Figure 16 It is the 3D printing scan power diagram of the bone plate in the present invention; Figure 17 It is the 3D printing scan speed diagram of the bone plate in the present invention; Figure 18 It is the layer thickness diagram of the 3D printing of the bone plate in the present invention.

[0015] In the figure: 1. Bone plate; 2. Screw hole. Specific embodiments

[0016] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0017] Embodiment 1

[0018] Please refer to Figures 1-18 , the present invention provides the following technical solutions: A novel 3D printed bone plate, comprising: Bone plate 1, which is made by an additive manufacturing process and has a local strengthening structure design for the strengthening area. Through a 3D printing strategy with a gradual change in energy density layer by layer, the density is increased at key parts to form a gradient material structure, significantly enhancing the local compressive and shear resistance capabilities; Screw hole 2, which is opened on the surface of bone plate 1; The local strengthening structure design includes an energy input strategy in the strengthening area. By adjusting the laser power, scan speed, and layer thickness, the energy density is gradually increased layer by layer in the strengthening area to form a density gradient; The enhanced area is made of TC4 titanium alloy powder by laser melting, with a laser power of 300 - 400 W, a scanning speed of 800 - 1000 mm / s, a layer thickness of 20 - 30 μm, and is fabricated into TC4-high material by 3D printing; The non-enhanced area is made of TC4 titanium alloy powder by laser melting, with a laser power of 200 - 300 W, a scanning speed of 1100 - 1200 mm / s, a layer thickness of 40 - 50 μm, and is fabricated into TC4-low material by 3D printing.

[0019] In a specific embodiment of the present invention, the bone plate 1 has a local enhanced structure design in the enhanced area, and the density and mechanical properties of key parts are improved through the strategy of energy density gradient change. Enhanced area: The parameter settings are a laser power of 300 - 400 W, a scanning speed of 800 - 1000 mm / s, and a layer thickness of 20 - 30 μm. In a way of increasing the energy density layer by layer, a density gradient is formed in the enhanced area, thereby significantly improving the compressive and shear resistance. Non-enhanced area: For areas that do not need to be enhanced, a lower laser power of 200 - 300 W, a higher scanning speed of 1100 - 1200 mm / s, and a larger layer thickness of 40 - 50 μm are used for printing to ensure the lightweight and economy of the overall structure. There are multiple screw holes 2 on the surface of the bone plate 1, and by inserting screws, it is used to fix the bone plate 1 to the bone. And the energy input strategy for the enhanced area is achieved by precisely adjusting the laser power, scanning speed, and layer thickness, ensuring the density and strength of the material at the key parts. Due to the gradient material structure design, it can better simulate the natural structure of the human bone and improve the compatibility with human tissues. Through the 3D printing strategy of layer-by-layer energy density gradient change, a gradient material structure is realized, enabling the bone plate 1 to have a significant improvement in local strength while ensuring the overall lightness. It can adjust the size and enhancement degree of the enhanced area according to the specific fracture situation of the patient to achieve personalized customization and improve the treatment effect. The additive manufacturing process is adopted. At the same time, personalized customization can reduce the number of surgeries and lower the treatment cost. This experiment is based on the standards of YY / T0342 - 2020 and YY / T1503 - 2016, and uses ANSYS Workbench2020 to establish a finite element model of the bone plate, simulate the mechanical response under the action of a compressive load, and extract the strain distribution data of different material properties. Among the three types of additive manufacturing bone plates: the maximum equivalent stress and strain of the locally enhanced bone plate are better than those of the non-enhanced bone plate, but slightly lower than those of the globally enhanced bone plate; the globally enhanced bone plate has too high an elastic modulus, while the elastic modulus of the bone is relatively low, which is easy to form stress shielding in the bone surface fitting area and affect the postoperative bone healing; Optimized design of the locally enhanced bone plate: This process adopts a precise gradient design and a dynamic adaptability optimization strategy; High-stress area: Implement enhancement processes on the bone plate at the bone distraction site to significantly improve the material's load-bearing performance; Fitting area: Retain the non-enhanced process to reduce the stress shielding effect; The locally enhanced bone plate performs optimally in core biomechanical indicators such as stress distribution uniformity and bone surface adaptability, and can effectively meet the clinical needs of complex fracture surgeries; Advantages of the locally enhanced bone plate: Embed 3D-printed bone plates of 3 specifications (non-enhanced, enhanced, locally enhanced) in the tooling in a specific manner, fix them on the testing machine, make the inner surface of the bone plate (the side in contact with the bone surface) face upward and parallel to the tabletop, place the bone plate so that the roller shaft contacts the inner surface of the bone plate, measure and record the distance a between the embedding interface and the center of the roller shaft (set to 20 mm), according to Figure 14 , Strength comparative analysis: In the static cantilever test, the average bending strength of the overall enhanced bone plate is 31.03 Nm, that of the locally enhanced bone plate is 26.9 Nm, and that of the non-enhanced bone plate is only 18.66 Nm. This shows that the overall enhanced bone plate significantly improves the static bending strength of the bone plate, with an obvious enhancement effect, while the effect of local enhancement is between that of overall enhancement and non-enhancement. Fatigue performance comparative analysis: In the dynamic cantilever test, 2 out of 3 samples of the non-enhanced bone plate fractured within one million cycles, while the samples of the overall enhanced and locally enhanced bone plates did not fracture, demonstrating the anti-fatigue performance of overall enhancement and local enhancement, enabling them to withstand more cycles of load without fracture. The overall enhancement and local enhancement processes have a positive impact on the mechanical properties of 3D-printed bone plates. In terms of static strength and dynamic fatigue performance, the overall enhanced bone plate performs the best, followed by the locally enhanced bone plate, while the non-enhanced bone plate is relatively weak. From the test results, the 3D-printed bone plates with overall enhancement and local enhancement are more advantageous in mechanical properties. The overall enhanced bone plate has a higher elastic modulus, which will cause stress shielding and affect postoperative bone recovery. The locally enhanced bone plate is more suitable for the actual medical application scenario and can better meet the requirements of the bone plate to resist static and dynamic loads during human use; Dynamic cantilever test: Set the hole distance to 17 mm, the roller shaft diameter to 10 mm, calibrate the axis of the test specimen to be perpendicular to the axis of the roller shaft, set the frequency to 10 Hz, and the R ratio to 0.1, and conduct a one-million-cycle test; Static cantilever test: Set the hole distance to 17 mm, the roller shaft diameter to 10 mm, and the loading rate to 0.04 mm / s, load until the bone plate fails, and record the relevant load and displacement data; The locally enhanced bone plate provides a new solution for the customized design of orthopedic implant devices by means of zonal performance regulation technology, taking into account both mechanical strength and adaptability.

[0020] For details, please refer to Figure 2, the design of the bone plate 1 is based on the DICOM file generated from the patient's CT / MRI data. The three-dimensional modeling software is used to simulate the shape of the bone after correction, and the position and angle of the enhanced area are planned to ensure precise matching with the patient's bone.

[0021] In this embodiment: During the design process, it is ensured that the bone plate 1 can achieve precise matching with the patient's bone. By adjusting the position and angle of the local enhanced structure to adapt to the unique anatomical structure of each patient, the treatment effect is maximized. The bone plate 1 designed based on the patient's specific CT / MRI data not only takes into account individual differences but also optimizes the position and angle of the enhanced area by precisely simulating the shape of the bone after correction. This personalized approach improves the success rate of treatment and patient satisfaction. The precisely matched bone plate 1 can better distribute stress, reduce the risk of postoperative complications, and promote a more natural bone healing process. By using the patient's own medical imaging data for design, it is ensured that the bone plate 1 can perfectly fit the patient's bone, provide the best support. The personalized design of the bone plate 1 can more accurately meet the treatment needs of patients, reduce the surgical risk, and enhance the treatment effect. Due to the high matching degree between the bone plate 1 and the patient's bone, the impact on surrounding tissues is reduced, which helps to accelerate postoperative recovery.

[0022] Specifically, please refer to Figures 16-18 , the mechanical properties of the local enhanced area and the surrounding materials transition smoothly, avoiding stress concentration caused by rigid mutation, while reducing the overall weight and rigidity, and reducing the stress shielding effect caused by the mismatch with the elastic modulus of the human bone.

[0023] In this embodiment: While ensuring that the local enhanced area has sufficient compressive and shear resistance, a smooth transition of the mechanical properties with the surrounding materials is achieved. This design not only effectively prevents stress concentration problems caused by rigid mutation but also reduces the weight and rigidity of the overall device, helping to reduce the occurrence of stress shielding effects. The design concept of smooth transition also takes into account the natural elastic modulus of the human bone, making the implant more in line with the biomechanical characteristics of human tissues, promoting a more natural healing process, reducing stress concentration problems that may be brought about by rigid mutation, improving the safety of the bone plate 1, not only enhancing the patient's comfort but also helping to improve the overall treatment effect.

[0024] Comparative Example 1 Please refer to Figures 8-11 , the present invention provides the following technical solution. The printing parameters of the non-enhanced bone plate are controlled as laser power 200 - 300W, scanning speed 1100 - 1200mm / s, and layer thickness 40 - 50μm.

[0025] This solution has; Defects of the non-enhanced bone plate; Fatigue failure risk: The equivalent strain and equivalent stress are the highest, and the plate shows obvious stress concentration in the high stress area. The stress and strain of the non-reinforced plate are the highest, indicating that its strength is relatively weak. When subjected to cyclic loads for a long time (such as the patient's gradual weight-bearing process), fatigue cracks are prone to propagate in the stress concentration area, resulting in a significantly higher risk of plate fracture than the locally enhanced plate. Micro-motion risk of the bone interface: Due to the highest equivalent strain, the interface between the plate and the bone is prone to small relative displacements (micro-motions) when subjected to stress, which may interfere with callus formation, prolong bone healing time, and even lead to nonunion. Comparative Example 2 See also Figures 8-11 The present invention provides the following technical solution: the printing parameters of the integrally enhanced bone plate are controlled as follows: laser power 300-400W, scanning speed 800-1000mm / s, and layer thickness 20-30μm.

[0026] The scheme exists; Overall enhancement of bone plate defects; Aggravated stress shielding effect: The equivalent strain and equivalent stress are the lowest, but due to its high elastic modulus, it may lead to stress shielding effect at the bone-plate interface and inhibit bone healing; Clinical operation limitations: The high elastic modulus makes the bone plate too rigid, and it is difficult to perform plastic micro-adjustments according to the bone anatomy during surgery, which may lead to insufficient fit between the bone plate and the bone surface, increase the risk of uneven force on the screws, and even cause micro-cracks inside the material due to forced shaping.

[0027] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A novel 3D printed bone plate, characterized in that: Comprising: An osteosynthesis plate (1), which is made by an additive manufacturing process and has a local reinforcement structure design for the reinforcement area. Through a 3D printing strategy with a gradual change in energy density layer by layer, the density is increased at key positions to form a gradient material structure, significantly enhancing the local compressive and shear resistance capabilities; Screw holes (2), which are opened on the surface of the osteosynthesis plate (1).

2. The novel 3D printing bone plate according to claim 1, wherein: The local reinforcement structure design includes an energy input strategy in the reinforcement area. By adjusting the laser power, scanning speed, and layer thickness, the energy density is gradually increased layer by layer in the reinforcement area to form a density gradient.

3. The novel 3D printing bone plate according to claim 2, wherein: In the additive manufacturing, the printing parameters used in the reinforcement area are controlled as follows: laser power 300 - 400W, scanning speed 800 - 1000mm / s, layer thickness 20 - 30μm, and the printing parameters used in the non-reinforcement area are controlled as follows: laser power 200 - 300W, scanning speed 1100 - 1200mm / s, layer thickness 40 - 50μm.

4. The novel 3D printing bone plate according to claim 3, characterized in that: The design of the osteosynthesis plate (1) is generated based on the DICOM file obtained from the patient's CT / MRI data. The morphology after bone correction is simulated through 3D modeling software, and the position and angle of the reinforcement area are planned to ensure precise matching with the patient's bone.

5. A novel 3D printed bone plate according to claim 4, characterized in that: The mechanical properties of the local reinforcement area and the surrounding materials have a smooth transition, avoiding stress concentration caused by sudden changes in rigidity. At the same time, the overall weight and rigidity are reduced, and the stress shielding effect caused by the mismatch with the elastic modulus of the human bone is reduced.

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