Method for manufacturing cartilage carving model

Abstract

The invention relates to a method for producing a cartilage sculpture model, to a cartilage sculpture model produced thereby, and also to the use of silicone for producing a cartilage sculpture model. The method comprises the following steps of: 1) performing three-dimensional reconstruction on cartilage by using software to generate a three-dimensional data model of the cartilage; 2) printing an organosilicon material on a substrate to form a first layer using a 3D printer, such as an extrusion 3D printer or a material jet 3D printer, according to the data model of the cartilage obtained in step 1), 3) continuing to print the same or different organosilicon material as in step 2) on the first layer using the 3D printer to form a subsequent layer, and 4) curing the first layer and the subsequent layer, optionally by heating or irradiation, thereby obtaining the cartilage sculpture model. The manufactured cartilage, especially the costal cartilage model, highly reduces the cartilage performance in the mechanical property, and has improved carving hand feeling and appearance accuracy.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a cartilage sculpture model, in particular to a method for manufacturing a cartilage sculpture model by using a 3D printing technology. Background of the Invention

[0003] Cartilage, such as rib cartilage, is a commonly used tissue material in plastic surgery, and is often used in operations such as ear reconstruction and rhinoplasty. In these operations, the cartilage needs to be carved, and whether the carving effect is beautiful depends on the surgical skills and experience of the plastic surgeon. There are large individual differences in the commonly used rib cartilage. The properties and size of rib cartilage vary greatly between different ages, genders, and individuals, which increases the difficulty of carving rib cartilage.

[0004] In order to improve the carving effect of these cartilages, doctors need to practice and train on cartilage materials for many years. Existing carving materials include animal cartilage, cadaver cartilage and hard materials (such as soap, carrots, etc.), as well as silicone models for casting.

[0005] However, although animal cartilage is closer to real cartilage in terms of mechanics and subjective carving experience, its appearance is quite different from human cartilage and there is a risk of spreading diseases; while human cadaver cartilage is difficult to obtain and there are ethical risks. As for simulated materials such as soap and carrots, although they do not spread diseases or have ethical risks, they are far from natural cartilage in terms of mechanics, subjective carving experience and appearance.

[0006] In addition, the model cast by mold casting can achieve a certain degree of appearance and subjective carving experience close to human cartilage, but the mold casting method is suitable for large-scale repeated production of teaching aids with exactly the same shape and size. For costal cartilage with large variations in shape and size, personalized customization and preoperative simulation cannot be achieved.

[0007] In addition, these models are often inaccurate, the printed models may have large errors from the original CAD models, and they also lack the carving feel.

[0008] Therefore, in view of these existing technologies, there is an urgent need to develop a better method for manufacturing cartilage carving models, which enables the cartilage models to be manufactured at low cost and customized, and the cartilage models should highly restore the performance of rib cartilage in terms of mechanical properties, have improved carving feel and shape accuracy, thereby facilitating doctors' daily carving training and preoperative simulation. SUMMARY OF THE INVENTION

[0010] The purpose of the present invention is to provide a method for manufacturing a cartilage sculpture model, by which the above-mentioned purpose of the invention can be achieved.

[0011] Another object of the present invention is to obtain a cartilage sculpture model by the manufacturing method, which can particularly have improved carving feel and shape accuracy and is highly close to the performance of cartilage in terms of mechanical properties. DETAILED DESCRIPTION OF THE INVENTION

[0013] In one aspect, the present invention relates to a method for manufacturing a cartilage sculpture model, in particular by additive manufacturing, comprising the following steps:

[0014] 1) Using software to three-dimensionally reconstruct cartilage and generate a three-dimensional data model of the cartilage;

[0015] 2) printing the silicone material on the substrate to form a first layer using a 3D printer such as an extrusion 3D printer or a material jetting 3D printer according to the cartilage data model obtained in step 1),

[0016] 3) using the 3D printer to continue printing the same or different silicone material as in step 2) on the first layer to form subsequent layers, and

[0017] 4) Curing the first and subsequent layers, optionally by heating or irradiation, to obtain a cartilage sculpture model.

[0018] In another aspect, the present invention relates to a cartilage sculpture model, in particular a rib cartilage, made by the manufacturing method as described above. Such a cartilage sculpture model is made of organic silicon material.

[0019] The inventors of the present application have discovered that the cartilage sculpture model made of silicone material using the method of the present invention can not only be customized according to the conditions of different patients, but also have improved carving feel and appearance accuracy.

[0020] In addition, the inventors have found that in order to make the printed cartilage model very close to the real cartilage when engraved, the selected silicone material must have a Shore A hardness in the range of 60-95, such as 62-92 or 60-85, more preferably 67 to 80, and a Young's modulus in the range of 5-26 MPa, such as 8-20 MPa or 11-18 MPa. The cartilage model such as the rib cartilage model prepared by the printing method of the present invention using such silicone material can have an excellent suture tolerance of 7-18N, especially 9-16N such as 9.5-14N.

[0021] In the context of the present invention, "Shore A Hardness" is measured at 23° C. using a cured sample of a curable silicone material according to ASTM D2240. According to this method, the test sample is obtained by press curing at 150° C. for 2 hours (this is how the Shore A hardness is expressed in the briefing book).

[0022] In the context of the present invention, "Young's modulus" is measured according to the method adopted in the following document:

[0023] Wang X,Dong W,Wang H,You J,Zheng R,Xu Y,Fan F.Mechanical properties of extensive calcified costal cartilage:An experimental study.Heliyon.2023Feb15;9(2):e13656.doi:10.1016 / j.heliyon.2023.e13656.PMID:36865463;PMCID:PMC9970894.

[0024] In the present invention, the cartilage model is engraved to evaluate the engraving feel by feeling whether the material sticks to the knife and the sense of obstruction during the process. An important indicator in judging the engraving feel and the final feel is the suture tolerance, which is a characterization of the ability to maintain the suture and the firmness of the stent during the suture assembly process. In this application, "suture tolerance" can be measured according to the method described in the following literature:

[0025] Pensalfini, M., Meneghello, S., Lintas, V., Bircher, K., Ehret, AE, Mazza, E. The suture retention test, revisited and revised. Journal of the MechanicalBehavior of Biomedical Materials 2018;77:711-717.

[0026] 3D printing is often associated with a number of related technologies for manufacturing physical objects from computer-generated (such as computer-aided design (CAD)) data sources.

[0027] This disclosure is generally incorporated into ASTM Designation F2792-12a, “Standard Terminology for Additive Manufacturing Technologies Under this ASTM standard.”

[0028] A “3D printer” is defined as “a machine used for 3D printing” and “3D printing” is defined as “the production of objects by deposition of material using a print head, nozzle or other printer technology”.

[0029] "Additive Manufacturing (AM)" is defined as "the process of joining materials from 3D modal data, typically layer by layer, to produce an object, as opposed to subtractive manufacturing techniques". Synonyms related to and covered by 3D printing include additive manufacturing, additive process, additive technology, additive layer manufacturing, layer manufacturing, and freeform manufacturing. Additive Manufacturing (AM) may also be referred to as Rapid Prototyping (RP). As used herein, "3D Printing" is generally interchangeable with "Additive Manufacturing" and vice versa.

[0030] "Printing" is defined as depositing a material (here, the silicone composition) using a print head, nozzle, or other printer technology.

[0031] In this disclosure, "3D or three-dimensional article, object or component" refers to an article, object or component obtained by additive manufacturing or 3D printing as disclosed above.

[0032] Generally, all 3D printing processes have a common starting point, which is a computer-generated data source or program that can describe an object. In the method of the present invention, the first step is to use software to three-dimensionally reconstruct cartilage and generate a three-dimensional data model of the cartilage. In a specific embodiment, the three-dimensional data model of the shape and structure of the cartilage can be generated by a computer by scanning the cartilage required by the patient, such as a CT scan.

[0033] The computer-generated data model of the cartilage is then converted into a Standard Tessellation Language (STL) file format; however, other file formats may be used or used in addition. The file is typically read into 3D printing software, which takes the file and optional user input information to divide it into hundreds, thousands, or even millions of "slices." The 3D printing software typically outputs machine instructions, which may be in the form of G-codes, which are read by a 3D printer to build each slice. The machine instructions are transmitted to the 3D printer, which then builds the object layer by layer based on the slice information in the form of machine instructions. The thickness of these slices may vary.

[0034] An extrusion 3D printer is a 3D printer in which material is extruded through a nozzle, syringe, or orifice during the additive manufacturing process. Material extrusion is typically performed by extruding material through a nozzle, syringe, or orifice to print one cross-section of an object, which may be repeated for each subsequent layer. The extruded material bonds to the layer below it during the curing of the material.

[0035] In a preferred embodiment, the method for additively manufacturing a three-dimensional silicone cartilage model product uses an extrusion 3D printer. The silicone material is extruded through a nozzle. The nozzle can be heated to help distribute the addition cross-linkable silicone material.

[0036] The average diameter of the nozzles defines the thickness of the layer. In one embodiment, the diameter of the layer is 50-2000 μm, preferably 100-800 μm and most preferably 100-500 μm.

[0037] The addition cross-linkable silicone material dispensed through the nozzle can be supplied by a cartridge-like system. The cartridge may include one or more nozzles with associated one or more fluid reservoirs. A coaxial dual cartridge system with a static mixer and only one nozzle may also be used. The pressure will be adapted to the fluid to be dispensed, the associated nozzle average diameter and the printing speed.

[0038] The nozzle and / or build platform moves in the XY (horizontal plane) to complete a cross section of the object before moving in the Z (vertical) plane once a layer is completed. After each layer is printed on the X,Y working plane, the nozzle is displaced in the Z direction just far enough to apply the next layer in the X,Y working position. In this way, the object that becomes a 3D article is built one layer at a time from bottom to top.

[0039] With the aid of a print head, the silicone material is applied discontinuously in the form of individual drops at the desired locations of the working plane. The device and method for the stepwise production of 3D structures using a print head arrangement comprising at least one, preferably 2-200 print head nozzles allows the position-selective application of multiple materials where appropriate.

[0040] In a material 3D jetting printer, one or more reservoirs are subjected to pressure and connected to a metering nozzle via a metering line. There may be a device upstream or downstream of the reservoir that enables uniform mixing of the multi-component addition-crosslinkable silicone material and / or discharge of dissolved gases. There may be one or more jetting devices that operate independently of each other to construct articles from different silicone materials.

[0041] Individual metering nozzles can be precisely positioned in the x, y and z directions to allow precise spot deposition of silicone rubber drops onto a substrate or, in the subsequent formation of a molded part, onto an already deposited and optionally cured addition-crosslinking silicone material.

[0042] Typically, a 3D printer uses a dispenser, such as a nozzle or print head, for printing a specific curable silicone composition. Optionally, the dispenser can be heated before, during, and after dispensing the silicone composition. More than one dispenser can be used, each with independently selected properties.

[0043] In one embodiment, such methods can use support materials to build the object. If support materials are used to print the object, they are typically removed after the printing process is complete, leaving the finished object.

[0044] In a specific embodiment of the second step of the method of the present invention, a layer of a first addition-crosslinked silicone material is printed on a substrate according to the data model of the cartilage obtained in step 1), so that the layer is formed on the substrate. The substrate is not limited and can be any substrate. The substrate can support the 3D article during the manufacturing method of the 3D article, for example as a substrate plate of a 3D printer. The substrate can be rigid or flexible and can be continuous or discontinuous. The substrate itself can be supported, for example by a substrate table or plate, so that the substrate does not need to have rigidity. It can also be removable from the 3D article. Alternatively, the substrate can be physically or chemically bonded to the 3D article. In one embodiment, the substrate itself can be silicone.

[0045] In one embodiment of the third step of the method of the present invention, the subsequent layer is formed by printing a second silicone material onto the previous layer formed in the first step using an extrusion 3D printer or a material 3D jet printer. The extrusion 3D printer and the material 3D jet printer may be the same as or different from the extrusion 3D printer or the material 3D jet printer used in step 1).

[0046] The second addition-crosslinkable silicone material may be the same as or different from the first addition-crosslinkable silicone material.

[0047] In a fourth step, a cartilage model made of silicone material is obtained by completely curing the first and subsequent layers, optionally by heating or irradiation. Curing can be done at ambient temperature. Typically, ambient temperature refers to a temperature of 20-25°C.

[0048] Heating can be used to accelerate the curing of the layer. Thermal curing of the first and subsequent layers after printing can be carried out at a temperature of 50-200°C, preferably 60-100°C, so as to achieve full curing more quickly. In one embodiment, the printed cartilage product can be heated in two steps, for example, at a temperature of 50-110°C or 60-100°C for curing for 15 minutes-2 hours, such as 0.5-1.5 hours, and then at a temperature greater than 100-200°C, such as 110°C or 115°C-180°C or 150°C for curing for 5 minutes-1 hour, such as 10 minutes-0.5 hours.

[0049] In this document, the term "layer" may refer to a layer at any stage of the process, the first layer or preceding layer or a subsequent layer. The layers may each have various dimensions, including thickness and width. The thickness of the layers may be uniform or may vary. The average thickness is related to the thickness of the layer just after printing.

[0050] In one embodiment, the layers independently have a thickness of 10-3000 μm, preferably 50-2000 μm, more preferably 100-800 microns and more preferably 100-600 microns.

[0051] In a particular embodiment, no energy source such as heat or radiation is applied, preferably during or between steps 2) to 3), before printing at least 10 layers, preferably 20 layers.

[0052] Optionally, finally, the prepared cartilage article can be subjected to various post-processing schemes, which can greatly improve the surface quality of the printed article. For example, sanding is a common way to reduce or eliminate distinct layers on the model. Also, for example, spraying or coating the surface of the elastomeric article with heat or UV curable RTV or LSR silicone materials can be used to obtain a suitable smooth surface appearance.

[0053] Surface treatment can also be performed using lasers.

[0054] In an advantageous embodiment, the final cartilage product can be sterilized and disinfected by heating the object at >100°C or in a UV oven.

[0055] The present invention will be further illustrated by the following examples, which are however intended to illustrate and not to limit the present invention. Example

[0056] Preparation of costal cartilage carving model

[0057] Patients who are scheduled to undergo costal cartilage removal surgery will undergo a chest CT scan before surgery to assess whether they are suitable for costal cartilage removal surgery, and the CT data will be used as imaging data for three-dimensional reconstruction.

[0058] Use 3D reconstruction software such as Mimics to perform 3D reconstruction on the CT data of the patient's costal cartilage that needs to be removed and save the reconstructed CAD model in STL format. Use software to slice the STL model of the costal cartilage and plan the printing path.

[0059] The rib cartilage teaching aids were made on a silicone 3D printer S300 using self-prepared organic silicon materials as the main material. The 3D printing equipment is liquid extrusion molding, has a dual-nozzle extrusion printing function, and an automatic cut-off system, which can print the main body and auxiliary support materials; the printer extrusion nozzle has a Z-axis avoidance function. Here, a 0.4mm extrusion nozzle and appropriate process parameters are selected for parametric slicing.

[0060] The key process parameters are as follows: scanning speed is 15 mm / s, layer thickness is 0.2 mm, filling rate is 100%, and material supply rate is 80%.

[0061] After printing is completed, the printed silicone rib cartilage is placed in an 80°C oven for heating and curing for 30-60 minutes, and then heated to 120°C for heating and curing for 15 minutes to complete the curing and molding of the product. Finally, the cured product is taken out for support removal, water washing, and drying to obtain the final product.

[0062] The printing accuracy of the printed rib cartilage teaching aids was evaluated according to the following tests:

[0063] The printed rib cartilage teaching aids were CT scanned for 3D reconstruction, and then the obtained STL model was put into the software together with the initial STL model for 3D comparison to obtain the accuracy comparison data. Figure 1 shown.

[0064] Figure 1 The different shades of color in the middle represent the difference between the original rib cartilage CAD model and the CAD model reconstructed by scanning the printed rib cartilage teaching aid. On the right is the scale of the difference value, which is within the range of ±7mm. After multiple tests, the accuracy of the 3D printed rib cartilage model is about 95%.

[0065] In this embodiment, three kinds of silicone materials are prepared for printing, and the measured properties of the three kinds of silicone materials are as follows:

[0066] Young's modulus (MPa) Suture tolerance (N) Shore A Hardness Silicone formula 1 9.0 15.3 65 Silicone Formula 2 14.8 10.8 75 Silicone formula 3 19.7 8.5 80

[0067] After comparison and testing with real rib cartilage, it was found that there was no statistical difference between silicone formulas 2 and 3 and rib cartilage in terms of Young's modulus, while silicone formula 1 had a significant difference, but it was still within the allowable range; in terms of suture tolerance, there was no statistical difference between silicone formulas 1 and 2 and natural rib cartilage, while formula 3 had a significant difference, but it was still within the acceptable range; in terms of Shore A hardness, there was no significant statistical difference between formulas 2 and 3 and natural rib cartilage, and although formula 1 had a significant difference, it was still acceptable.

Claims

1. A method for manufacturing a cartilage sculpture model by additive manufacturing, comprising the following steps: 1) Using software to three-dimensionally reconstruct cartilage, especially costal cartilage, to generate a three-dimensional data model of the cartilage; 2) Printing the silicone material on the substrate using a 3D printer to form a first layer according to the three-dimensional data model of the cartilage obtained in step 1), 3) using the 3D printer to continue printing the same or different silicone material as in step 2) on the first layer to form subsequent layers, and 4) Curing the first and subsequent layers, optionally by heating or irradiation, to obtain a cartilage sculpture model.

2. The method according to claim 1, characterized in that In step 1), a three-dimensional data model of the shape and structure of the cartilage is generated by a computer by scanning the cartilage to be manufactured, such as a CT scan.

3. The method according to claim 1, characterized in that The printer is selected from an extrusion 3D printer or a material jetting 3D printer.

4. The method according to claim 1, characterized in that In step 4) the applied first and subsequent layers are cured by heating, preferably at a temperature of 50-200°C, preferably 60-100°C.

5. The method according to claim 1, characterized in that The silicone material has a Shore A hardness in the range of 60-95, such as 62-92 or 60-85, more preferably 67 to 80, and a Young's modulus in the range of 5-26 MPa, such as 8-20 MPa or 11-18 MPa.

6. A cartilage sculpture model made by the manufacturing method according to any one of claims 1 to 4, in particular a rib cartilage sculpture model.

7. The model according to claim 6, which has a suture resistance of 7-18N, in particular 9-16N.

8. Use of silicone materials in making cartilage sculpture models.

9. The use according to claim 8, characterized in that The silicone material has a Shore A hardness in the range of 60-95, such as 62-92 or 60-85, more preferably 67 to 80, and a Young's modulus in the range of 5-26 MPa, such as 8-20 MPa or 11-18 MPa.

10. Use according to claim 8 or 9, characterized in that The cartilage sculpture model was produced by additive manufacturing, which included the following steps: 1) Using software to three-dimensionally reconstruct cartilage and generate a three-dimensional data model of the cartilage; 2) printing the silicone material on the substrate to form a first layer using a 3D printer such as an extrusion 3D printer or a material jetting 3D printer according to the cartilage data model obtained in step 1), 3) using the 3D printer to continue printing the same or different silicone material as in step 2) on the first layer to form subsequent layers, and 4) Curing the first and subsequent layers, optionally by heating or irradiation, to obtain a cartilage sculpture model.

11. Use according to claim 10, characterised in that The cartilage is costal cartilage.

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