A skull implant and a method for preparing the same

Abstract

The present invention relates to a skull implant and a preparation method thereof, comprising: establishing a three-dimensional defect model of a patient through digital medical imaging technology, and performing customized design of a skull repair system to obtain a skull prototype; performing a skull plate interface porous structure design on the skull prototype, generating a longitudinally penetrating pore structure perpendicular to the human body contact surface at the skull and human body contact surface by a method of offset curved surface and array removal, and obtaining a skull model; performing 3D printing on the skull model, using polyetheretherketone or modified polyetheretherketone, the print head temperature is 350℃-500℃, and the thermal atmosphere temperature of the printing chamber is 90℃-250℃. The skull implant obtained by the preparation method perfectly matches the skull defect site of the patient, has a smooth surface, and can be closely combined with human tissue, which is conducive to postoperative bone regeneration, thereby solving the problems of poor prosthesis adaptability, postoperative toxic reactions, poor fusion, and long-term implant failure risk in skull plate replacement surgery.

Description

Technical Field

[0001] The invention relates to the technical field of medical devices, in particular to a skull implant and a preparation method thereof. Background Art

[0002] Millions of surgeries are performed worldwide every year to replace skull plates. Autologous and allogeneic bone are the gold standard for skull defect treatment; however, due to the shortage of bone supply and the difficulty in adapting and molding, other biomaterials are forced to be used in large quantities in the surgical field to replace the shortage of autologous or allogeneic bone sources. Among them, skull defect prosthesis products made of titanium metal materials, polyetheretherketone (PEEK) materials, and bioceramic materials through machining, injection molding, sintering, etc. have been widely used in clinical practice, but the current existing technologies for skull repair products still have the following disadvantages:

[0003] First, metal skull implants have difficulty meeting biomechanical requirements. In particular, stress shielding around implants is a common problem, which can occur at the interface between metal and bone and lead to surrounding bone loss. In addition, metal-based implants may corrode surrounding tissues and cause cytotoxic reactions by releasing metal ions into the host body.

[0004] Second, PEEK material is highly hydrophobic, making it difficult to form good bone tissue adhesion at the surface interface. Currently, the main way to solve this problem is surface modification, but the modification process is prone to change the properties of the base material, and the surface modification coating and other technologies have poor bonding performance with the base, which is easy to fall off, resulting in the risk of long-term implant failure of the product after surgery.

[0005] 3. Bioceramics have excellent biological activity and chemical properties similar to natural human bones, and are gradually being valued by the market. However, the low mechanical strength and brittleness of large-area ceramics limit their application in bone repair.

[0006] Fourth, the current manufacturing methods are mainly subtractive methods such as machining and injection molding. There are problems such as limited raw material specifications, large amounts of material waste caused by cutting, single nature of molded samples, expensive fixtures and molds and long cycles. They cannot adapt to the complex customized products of medical batch manufacturing with complex curvatures.

[0007] 5. The existing machined and injection molded products have smooth surfaces, which can also make it difficult for osteoblasts to adhere, differentiate, and proliferate, resulting in a lack of space for bone tissue regeneration, making it difficult to achieve bone regeneration and good interface integration. Summary of the invention

[0008] The purpose of the present invention is to overcome the problems existing in the existing skull implants and provide a method for preparing the skull implants. The skull implants produced can achieve personalized and precise shaping of the patient, can improve the matching degree with the surrounding tissues of the defective part of the patient, perfectly match the physiological curvature and size of the patient's maxillofacial region, and the porous structure ensures that the implant is not easy to slip or loosen after implantation, and can achieve the characteristics of close combination with the surrounding bone tissue. At the same time, it ensures that the support is easy to remove and is not easy to cause residue in the solid part of the part.

[0009] The specific plan is as follows:

[0010] A method for preparing a skull implant comprises the following steps:

[0011] (1) Use digital medical imaging technology to establish a three-dimensional defect model of the patient and customize the design of the skull repair system to obtain a skull prototype;

[0012] (2) Designing a porous structure of the skull plate interface for the skull prototype, generating a porous structure at the contact surface between the skull and the human body by using an offset curved surface and array removal method to obtain a skull model;

[0013] (3) 3D printing is performed on the skull model using polyetheretherketone or modified polyetheretherketone material, with a print head temperature of 350°C-500°C and a printing chamber hot atmosphere temperature of 90°C-250°C, and printing is performed in the following order:

[0014] First, a support column for supporting the skull implant is printed, wherein the support column is determined according to the placement angle of the skull model, and the support column is formed in the gap between the skull model and the printing base plate after the skull model is placed;

[0015] Then, the skull implant is printed on the support column, and the filling and skull contour are printed layer by layer, that is, the skull contour is printed first, and then the solid part and the porous part are filled between the contours, and the porous part is a plurality of array holes combined to form a ring around the solid part; during the printing process, the printing material is extruded through the print nozzle and then retracted, and the retraction speed of the retraction action is 1500-1800mm / min, the nozzle is lifted 0.2-1mm during retraction, and retracted 4-7mm, and then extruded again after retraction to compensate 0.2-1mm, and the sliding distance is 0.1-1mm;

[0016] Finally, the supports and burrs of the printed object are removed to obtain a skull implant with a solid interior and a porous osteosynthesis surface.

[0017] Furthermore, the digital medical imaging technology described in step (1) adopts CT scanning, and the layer thickness of the layered scanning data should not be greater than 1 mm; the establishment of the three-dimensional defect model is through the image threshold segmentation algorithm, setting the grayscale threshold, separating the skull defect model area, and generating a three-dimensional data format file composed of a triangular patch structure.

[0018] Furthermore, the customized design of the skull repair system in step (1) includes symmetrically mirroring the 3D model data of the patient's defective part, filling the intact area into the corresponding defective area in a mirrored manner, and completing the edge and position matching of the skull through a combination of Boolean operations, translation, rotation and redesign.

[0019] Furthermore, the pore size of the pore structure in step (2) is in the range of 200-2000um, the thickness of the pore wall is in the range of 300um-800um, and the longitudinal depth of the pore size is 1-2mm.

[0020] Furthermore, the modified polyetheretherketone in step (3) is a mixture of polyetheretherketone and biphasic calcium phosphate ceramic, wherein the mass ratio of the biphasic calcium phosphate ceramic is 0-50%, preferably 10%-20%;

[0021] Optionally, the aperture specification of the printing nozzle is 0.1-1 mm, preferably 0.2 mm-0.6 mm;

[0022] Optionally, the printing layer thickness is 0.1-0.3 mm, preferably 0.15-0.2 mm;

[0023] Optionally, the extrusion ratio of the printing nozzle is 0.8-1.

[0024] Furthermore, in step (3), the skull model is placed at an angle of ≤45° between the skull model and the printing base plate, and the print head is controlled to be perpendicular to the printing base plate and move at a distance of ≥5 mm away from the printing base plate to generate an array of support columns. Preferably, the length of the support columns is ≥1 mm and the width is ≥1 mm.

[0025] Optionally, the bottom filling rate of the support column is controlled to be 40%-60%, and the top filling rate is controlled to be 80%-100%.

[0026] Furthermore, the printing nozzle performs reciprocating printing in one direction, so that the distance between the top surface of the support column and the bottom surface of the skull model is 0.3-0.5 mm, thereby completing the printing of the support column.

[0027] Furthermore, in step (3), when printing the skull implant, the solid part is filled with a filling rate of 60%-100%, the overlapping rate of the outline filling is 30%-50%, and the number of shells is 1-3 layers;

[0028] Optionally, the porous part is formed by using a three-dimensional porous array design model in combination with a filling strategy and material feed control. The filling strategy is a path planning for 3D printing material accumulation, so that the material accumulation path runs along the model of the porous structure design. The material feed control is to precisely control the extrusion feeding and withdrawal of the material through a gear mechanism, and cooperate with the path planning to accurately accumulate the material on the porous designed structure.

[0029] Furthermore, in step (3), supports and burrs are removed when the temperature of the printed object is 50-150°C, preferably 80-120°C.

[0030] The present invention also protects the skull implant prepared by the skull implant preparation method.

[0031] Beneficial effects:

[0032] In the present invention, a three-dimensional defect model of the patient is established through digital medical imaging technology, and a customized design of the skull repair system is performed to obtain a skull prototype that can better match the patient's skull shape. Polyetheretherketone or modified polyetheretherketone is used as a printing material to accelerate bone exchange after implantation, improve the healing speed of patient tissues, and solve the problems of interface contact bone loss and toxic reactions caused by metal ion release in metal skull implants.

[0033] Furthermore, the present invention designs a porous structure of the skull plate interface for the skull prototype, and generates a pore structure, i.e. a hollow part, at the contact surface between the skull and the human body by means of offset curved surface and array removal, which can provide space for bone growth after surgery, accelerate bone exchange, increase the healing speed of patient tissues, and improve postoperative recovery effects.

[0034] Furthermore, the present invention forms a combination of solid parts and hollow parts through layer printing to obtain an excellent texture structure, which can effectively promote the adhesion, differentiation and proliferation of osteoblasts and improve the skull repair effect.

[0035] In summary, the skull implant obtained by the preparation method of the present invention perfectly matches the skull defect of the patient, has a smooth surface, and can be tightly integrated with human tissue, which is beneficial to postoperative bone regeneration, thereby solving the problems of poor adaptability, postoperative toxic reactions, and long-term implant failure risks in skull plate replacement surgery, and has excellent market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings will be briefly introduced below. Obviously, the accompanying drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0037] Figure 1 is a process flow chart provided by one embodiment of the present invention;

[0038] Figure 2 is an image grayscale threshold segmentation map provided by an embodiment of the present invention;

[0039] Figure 3 It is a design drawing of a personalized skull plate provided by one embodiment of the present invention;

[0040] Figure 4 is a schematic diagram of a solid portion of a skull implant provided by one embodiment of the present invention;

[0041] Figure 5 is a schematic diagram of a porous portion of a skull implant provided by an embodiment of the present invention;

[0042] Figure 6 is an offset curved surface diagram of a skull implant provided by one embodiment of the present invention;

[0043] Figure 7 is a schematic diagram of a multi-hole array in a skull implant provided by an embodiment of the present invention;

[0044] Figure 8 A figure after triangular facet data conversion provided by an embodiment of the present invention;

[0045] Fig. 9 It is a support column design and slice preview diagram of a skull implant provided by one embodiment of the present invention;

[0046] Fig.10 It is a schematic diagram of the internal filling structure of a skull implant provided by one embodiment of the present invention;

[0047] Fig.11 It is a schematic diagram of a solid part performing non-return empty walking provided by an embodiment of the present invention;

[0048] Fig.12 It is a schematic diagram of a porous part performing non-return emptying provided by an embodiment of the present invention;

[0049] Fig.13 The invention is a finished skull implant provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0050] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. In the examples, those without specifying specific techniques or conditions are carried out according to the techniques or conditions described in the literature in this area or according to the product specification. Those without specifying the manufacturer of reagents or instruments used are all conventional products that can be obtained commercially. In the following examples, if not clearly stated, "%" refers to weight percentage.

[0051] Example 1

[0052] A method for preparing a skull implant, the process flow is as follows Figure 1 As shown, the main steps include: based on the clinical needs of medical institutions, reconstructing the patient's three-dimensional defect model through digital medical imaging technology and customizing the skull repair system, adding corresponding process support structures, setting optimized melt extrusion deposition process parameters, processing the debugged printing model data by slicing layer by layer and transmitting it to the equipment, using polyetheretherketone (PEEK) and biphasic calcium phosphate (BCP) physically mixed and filled filaments for 3D printing, removing supports and burrs after molding, and finally forming a customized skull implant with a solid interior and porous bone interface.

[0053] The specific steps include:

[0054] (1) Use digital medical imaging technology to establish a three-dimensional defect model of the patient and customize the design of the skull repair system to obtain a skull prototype;

[0055] (2) Designing a porous structure of the skull plate interface for the skull prototype, generating a longitudinally penetrating pore structure perpendicular to the human body contact surface at the skull contact surface with the human body by using an offset curved surface and array removal method, thereby obtaining a skull model;

[0056] (3) 3D printing is performed on the skull model using polyetheretherketone or modified polyetheretherketone, with a print head temperature of 350°C-500°C and a printing chamber hot atmosphere temperature of 90°C-250°C, and printing is performed in the following order:

[0057] First, a support column for supporting a skull implant is printed, wherein the support column is determined according to the placement angle of the skull model, and the support column is formed in the gap between the skull model and the printing base plate after placement, and the bottom filling rate of the support column is controlled to be 40%-60%, and the top surface filling rate is controlled to be 80%-100%;

[0058] Then, a skull implant is printed on the support column, and a filling and skull contour printing and molding method is adopted, that is, the skull contour is printed first, and then a solid part and a pore structure are formed by filling between the contours, the solid part is filled with a filling rate of 60%-100%, the overlap rate of the contour and the filling is 30%-50%, and the number of shells is 1-3 layers, so as to obtain a molded object;

[0059] Finally, the supports and burrs are removed from the molded product to obtain a skull implant with a solid interior and a porous osteosynthesis surface.

[0060] The following is a detailed description of each step:

[0061] In step (1), the thickness of the thin-layer CT scan image data of the patient should be no greater than 1 mm, preferably 0.1-0.5 mm, so as to obtain sufficient data for the next step of model building.

[0062] The three-dimensional defect model is segmented by an image threshold algorithm by setting a suitable grayscale threshold such as Figure 2 , separate the skull defect model area and produce a three-dimensional data format with a triangular patch structure.

[0063] The customized design of the skull repair system is mainly achieved by symmetrically processing the 3D model data of the defective part of the patient, filling the intact area into the corresponding defective area in a mirrored manner, and completing the edge and position matching of the customized product through Boolean operations, translation, rotation, redesign, etc. Figure 3 shown.

[0064] In step (2), the skull prototype is subjected to a skull plate interface porous structure design, and a regular porous structure suitable for bone ingrowth is designed at the skull plate bone grafting interface. Specifically, a through-pore structure with a longitudinal depth of 1-2 mm is generated at the contact surface between the skull and the human body by means of an offset curved surface and array removal method. The porous structure is a square opening with a pore size ranging from 200 to 2000 um and a pore wall thickness ranging from 300 um to 800 um. The overall structure is as follows: Figures 4 to 8 shown.

[0065] In step (3), 3D printing is performed on the skull model, using polyetheretherketone (PEEK) or modified polyetheretherketone, preferably modified polyetheretherketone, and bioceramic biphasic calcium phosphate (BCP) to modify polyetheretherketone to improve the biocompatibility of the material. The modified material overcomes the biological inertness of the PEEK material and the low mechanical properties and brittleness of the bioceramic material, thereby obtaining a material with comprehensive mechanical and biological properties. Preferably, the content range of BCP can be between 0% and 50%, and the preferred content range is between 10% and 20%, which can obtain excellent comprehensive mechanical and biocompatibility properties.

[0066] The print head temperature is 350℃-500℃, and the print chamber thermal atmosphere temperature is 20℃-250℃. At the above temperatures, the print head and chamber thermal atmosphere temperature are conducive to ensuring stable crystallization during the printing process, improving the interlayer bonding performance of the product, and preventing the delamination phenomenon caused by poor interlayer bonding that is common in FDM printing.

[0067] First, print the support column for supporting the skull implant. The support design of the skull model is generated when the overhang angle is ≤45°, that is, the angle between the skull model and the printing base is ≤45°. The print head performs unidirectional reciprocating printing, the bottom filling rate is 40%-60%, the offset distance between the skull model and the top surface of the support column is generally 0.3-0.5mm, the top surface of the support column has 1-3 dense support layers, and the top surface filling rate of the support column is 80%-100%, so as to ensure the integrity and smoothness of the skull repair product at the support interface and have good removability, such as Fig. 9 shown.

[0068] Preferably, the skull model is placed at an angle with a maximum projection area on the base plate, and is moved perpendicular to the base plate and at a distance of ≥5 mm away from the base plate to generate a square support column with a length and width of ≥1 mm.

[0069] The skull implant is printed on top of the support column. The key printing parameters include printing layer thickness, nozzle temperature, chamber atmosphere temperature, printing layer thickness, filling strategy, etc. For example, the printing layer thickness is 0.1-0.3mm, and the aperture specifications of the melt extrusion nozzle are 0.2mm, 0.4mm, and 0.6mm. Using 0.2mm thickness and 0.4mm nozzle is conducive to improving the printing efficiency of the product while ensuring good interlayer bonding. The extrusion ratio is set to 0.8-1.

[0070] The skull implant is mainly divided into a solid part and a porous part, wherein the solid part corresponds to the main body of the skull plate and the porous part corresponds to the bone bonding interface. It should be noted that the solid part must have a hole structure, which is mainly for drainage to prevent the risk of implant failure caused by fluid accumulation at the skull repair site, and can also be used for dura mater suspension threading.

[0071] The solid part of the skull implant is filled with a filling rate of 60%-100%, with a filling strategy in the form of a 45° / 45° grid. The overlap rate between the shell and the filling is 30%-50%, and the number of shells is set to 1-3 layers, which can provide a certain degree of elasticity for the 3D printed skull implant while ensuring the overall mechanical properties.

[0072] The main body of the skull plate has high requirements for surface finish and integrity, so filling + multi-layer contour molding can be used to ensure the quality of the outer surface, such as Fig.10 As shown. The molten extrusion 3D printing FDM technology (full name: Fused Deposition Modeling) generally transmits materials through gears, and controls the extrusion and retraction of materials to achieve precise molding of solid and porous structural parts.

[0073] The porous structure printing of skull implants requires leakage control. Fig.11 and Fig.12 As shown, the extruded wire is retracted in stages, that is, the retraction speed is 1500-1800mm / min, the nozzle is lifted 0.2-1mm during retraction, 4-7mm is retracted, and the extrusion compensation is 0.2-1mm after retraction, and the sliding distance is 0.1-1mm. Retraction can avoid overflow and wire drawing when the material moves at the transition position of the porous structure during printing, and ensure the permeability of the porous structure in the XY direction.

[0074] Finally, the molded object is de-supported and deburred. After printing is completed, the sample can be removed from the bottom plate of the equipment at around 50-150°C, preferably at around 100°C. It is easy to peel off as a whole with less residue. The remaining burrs can be removed one by one by a tool to finally form a product.

[0075] Example 2

[0076] This embodiment is improved on the basis of embodiment 1, and the specific steps are as follows:

[0077] A three-dimensional defect model of the patient is established through digital medical imaging technology, and a customized design of the skull repair system is performed to obtain a skull prototype; the skull prototype is subjected to a skull plate interface porous structure design, and a longitudinally penetrating pore structure perpendicular to the human body contact surface is generated at the skull contact surface with the human body by using the offset curved surface and array removal method to obtain a skull model. The skull implant is 94mm long and 88mm wide. There are multiple holes on the side of the skull implant around the bone connection. The square porous structure is 0.6mm long and wide, with a hole wall thickness of 0.6mm, a matrix arrangement distribution, and a depth of 2mm.

[0078] The designed skull implant model was printed, and a mixture of polyetheretherketone and biphasic calcium phosphate ceramic (content 20wt%) was used as the printing material. The print head diameter was selected to be 0.4mm, the extrusion ratio was 0.9, the printing temperature was 485℃, the ambient temperature was 230℃, and the layer height was 0.2mm. The skull implant includes a solid part and a porous part, wherein the solid part is evacuated without backflow, and the porous part is backflowed. The backflow speed of the backflow is 1500mm / min, the nozzle is lifted by 0.5mm during backflow, 5mm is backflowed, and 0.5mm is extruded again after backflow to compensate, and the sliding distance is 0.5mm.

[0079] First print the support column to make a solid support along the bottom outer contour of the skull implant, with a minimum support height of 5mm. The length and width of the support column are set to 2mm, and it is automatically generated when the overhang angle is less than 45°, with a horizontal offset of 0.5mm, and a support bottom filling rate of 40%; the top surface has 3 dense support layers with a filling rate of 80%.

[0080] Then print the skull implant, with a filling rate of 90% for the solid part of the skull implant, a filling angle of 45° / 45°, an overlap rate of 30% between the shell and the filling, and the number of shells set to 1 layer.

[0081] After printing, when the temperature drops to 100°C, the part and the support are removed from the base plate and the support is removed from the part at the same time to obtain a skull implant with a smooth surface.

[0082] Example 3

[0083] This embodiment is improved on the basis of embodiment 1, and the specific steps are as follows:

[0084] A three-dimensional defect model of the patient is established through digital medical imaging technology, and a customized design of the skull repair system is performed to obtain a skull prototype; the skull prototype is subjected to a skull plate interface porous structure design, and a longitudinally penetrating pore structure perpendicular to the human body contact surface is generated at the skull contact surface with the human body by using the offset curved surface and array removal method to obtain a skull model. The skull implant is 94mm long and 88mm wide. There are multiple holes on the side of the skull implant around the bone connection. The square porous structure is 0.6mm long and wide, with a hole wall thickness of 0.6mm, a matrix arrangement distribution, and a depth of 2mm.

[0085] The designed skull implant model was printed, and a mixture of polyetheretherketone and biphasic calcium phosphate ceramic (content 10wt%) was used as the printing material, wherein the print nozzle diameter was selected to be 0.2mm, the extrusion ratio was: 0.9, the printing temperature was 380℃, the ambient temperature was 120℃, and the layer height was 0.2mm. The skull implant includes a solid part and a porous part, wherein the solid part is idling without retraction, and the porous part is retracting, and the retraction speed of the retraction action is 1700mm / min, the nozzle is lifted 0.2mm during retraction, 4mm is retracted, and 0.2mm is extruded again after retraction to compensate, and the sliding distance is 0.2mm.

[0086] First print the support column to make a solid support along the bottom outer contour of the skull implant, with a minimum support height of 5mm. The length and width of the support column are set to 1.5mm, and it is automatically generated when the overhang angle is less than 45°, with a horizontal offset of 0.5mm, and a support bottom filling rate of 40%; the top surface has 3 dense support layers with a filling rate of 80%.

[0087] Then print the skull implant, with a filling rate of 60% for the solid part of the skull implant, a filling angle of 45° / 45°, an overlap rate of 30% between the shell and the filling, and the number of shells set to 1 layer.

[0088] After printing, when the temperature drops to 100°C, the part and the support are removed from the base plate and the support is removed from the part at the same time to obtain a skull implant with a smooth surface.

[0089] Example 4

[0090] This embodiment is improved on the basis of embodiment 1, and the specific steps are as follows:

[0091] A three-dimensional defect model of the patient is established through digital medical imaging technology, and a customized design of the skull repair system is performed to obtain a skull prototype; the skull prototype is subjected to a skull plate interface porous structure design, and a longitudinally penetrating pore structure perpendicular to the human body contact surface is generated at the skull contact surface with the human body by using the offset curved surface and array removal method to obtain a skull model. The skull implant is 94mm long and 88mm wide. There are multiple holes on the side of the skull implant around the bone connection. The square porous structure is 0.6mm long and wide, with a hole wall thickness of 0.6mm, a matrix arrangement distribution, and a depth of 2mm.

[0092] The designed skull implant model was printed, and a mixture of polyetheretherketone and biphasic calcium phosphate ceramic (content 20wt%) was used as the printing material. The print head diameter was 1mm, the extrusion ratio was 0.9, the printing temperature was 410℃, the ambient temperature was 150℃, and the layer height was 0.2mm. The skull implant includes a solid part and a porous part, wherein the solid part is evacuated without backflow, and the porous part is backflowed. The backflow speed of the backflow is 1800mm / min, the nozzle is lifted 1mm during backflow, 6mm is backflowed, and 1mm is extruded again after backflow to compensate, and the sliding distance is 0.8mm.

[0093] First print the support column to make a solid support along the bottom outer contour of the skull implant, with a minimum support height of 5mm. The length and width of the support column are set to 3mm, and it is automatically generated when the overhang angle is less than 45°, with a horizontal offset of 0.5mm, and a support bottom filling rate of 50%; the top surface has 3 layers of dense support layers with a filling rate of 90%.

[0094] Then print the skull implant, with a 100% filling rate for the solid part of the skull implant, a filling angle of 45° / 45°, a 50% overlap between the shell and the filling, and the number of shells set to 1 layer.

[0095] After printing, when the temperature drops to 100°C, the part and the support are removed from the base plate and the support is removed from the part at the same time to obtain a skull implant with a smooth surface.

[0096] Example 5

[0097] This embodiment is improved on the basis of embodiment 1, and the specific steps are as follows:

[0098] A three-dimensional defect model of the patient is established through digital medical imaging technology, and a customized design of the skull repair system is performed to obtain a skull prototype; the skull prototype is subjected to a skull plate interface porous structure design, and a longitudinally penetrating pore structure perpendicular to the human body contact surface is generated at the skull contact surface with the human body by using the offset curved surface and array removal method to obtain a skull model. The skull implant is 94mm long and 88mm wide. There are multiple holes on the side of the skull implant around the bone connection. The square porous structure is 0.6mm long and wide, with a hole wall thickness of 0.6mm, a matrix arrangement distribution, and a depth of 2mm.

[0099] The designed skull implant model was printed, and a mixture of polyetheretherketone and biphasic calcium phosphate ceramic (content 20wt%) was used as the printing material, wherein the print nozzle diameter was selected to be 0.5mm, the extrusion ratio was: 0.9, the printing temperature was 450℃, the ambient temperature was 90℃, and the layer height was 0.2mm. The skull implant includes a solid part and a porous part, wherein the solid part is idling without retraction, and the porous part is retracting, and the retraction speed of the retraction action is 1600mm / min, the nozzle is lifted 0.8mm during retraction, 4mm is retracted, and 0.4mm is extruded again after retraction to compensate, and the sliding distance is 0.4mm.

[0100] First print the support column to make a solid support along the bottom outer contour of the skull implant, with a minimum support height of 5mm. The length and width of the support column are set to 2mm, and it is automatically generated when the overhang angle is less than 45°, with a horizontal offset of 0.5mm, and a support bottom filling rate of 60%; the top surface has 3 dense support layers with a filling rate of 100%.

[0101] Then print the skull implant, with a filling rate of 90% for the solid part of the skull implant, a filling angle of 45° / 45°, an overlap rate of 40% between the shell and the filling, and the number of shells set to 1 layer.

[0102] After printing, when the temperature drops to 100°C, the part and the support are removed from the base plate and the support is removed from the part at the same time to obtain a skull implant with a smooth surface.

[0103] Comparative Example 1

[0104] This example refers to Example 2. Under the same other conditions, after adjusting the internal ambient temperature of the 3D printing equipment chamber from 230°C to less than 80°C, the color of the 3D printed product is dark and translucent. In this state, the PEEK material is in an amorphous state, and the strength of the final product is much weaker than that of the crystalline product. The product printing process shows obvious delamination and warping. As the 3D printing process proceeds, the product warping will become more and more serious until the printing process can no longer proceed.

[0105] Comparative Example 2

[0106] This embodiment refers to Embodiment 2. When other conditions are the same, the porous part is retracted at a speed of 1500 mm / min and 5 mm is retracted. The porous part is changed to not retracting or retracting at a speed of less than 1000 mm / min and 1 mm is retracted. Because at the starting end of the porous structure, the material feed amount (extrusion & retraction) and feed speed (extrusion & retraction) do not match the printing rate, the material overflows significantly at the starting end, the open space of the porous part is clogged, burrs occur, and the connectivity of the porous structure is affected.

[0107] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0108] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0109] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a skull implant, characterized in that: The following steps are involved: (1) Use digital medical imaging technology to establish a three-dimensional defect model of the patient and customize the design of the skull repair system to obtain a skull prototype; (2) Designing a porous structure of the skull plate interface for the skull prototype, generating a porous structure at the contact surface between the skull and the human body by using an offset curved surface and array removal method to obtain a skull model; (3) 3D printing is performed on the skull model using polyetheretherketone or modified polyetheretherketone material, with a print head temperature of 350°C-500°C and a printing chamber hot atmosphere temperature of 90°C-250°C, and printing is performed in the following order: First, a support column for supporting the skull implant is printed, wherein the support column is determined according to the placement angle of the skull model, and the support column is formed in the gap between the skull model and the printing base plate after the skull model is placed; Then, the skull implant is printed on the support column, and the filling and skull contour are printed layer by layer, that is, the skull contour is printed first, and then the solid part and the porous part are filled between the contours, and the porous part is a plurality of array holes combined to form a ring around the solid part; during the printing process, the printing material is extruded through the print nozzle and then retracted, and the retraction speed of the retraction action is 1500-1800mm / min, the nozzle is lifted 0.2-1mm during retraction, and retracted 4-7mm, and then extruded again after retraction to compensate 0.2-1mm, and the sliding distance is 0.1-1mm; Finally, the supports and burrs of the printed object are removed to obtain a skull implant with a solid interior and a porous osteosynthesis surface.

2. The method for preparing the skull implant according to claim 1, characterized in that: The digital medical imaging technology described in step (1) adopts CT scanning, and the layer thickness of the layered scanning data should not be greater than 1 mm; the establishment of the three-dimensional defect model is through the image threshold segmentation algorithm, setting the grayscale threshold, separating the skull defect model area, and generating a three-dimensional data format file composed of a triangular patch structure.

3. The method for preparing the skull implant according to claim 1 or 2, characterized in that: The customized design of the skull repair system in step (1) includes symmetrically mirroring the 3D model data of the patient's defective part, filling the intact area into the corresponding defective area in a mirrored manner, and completing the edge and position matching of the skull through a combination of Boolean operations, translation, rotation and redesign.

4. The method for preparing the skull implant according to claim 1, characterized in that: The pore size of the pore structure in step (2) is between 200-2000um, the thickness of the pore wall is between 300um-800um, and the longitudinal depth of the pore size is 1-2mm.

5. The method for preparing the skull implant according to claim 1, characterized in that: The modified polyetheretherketone in step (3) is a mixture of polyetheretherketone and biphasic calcium phosphate ceramics, wherein the mass proportion of the biphasic calcium phosphate ceramics is 10%-20%.

6. The method for preparing the skull implant according to claim 5, characterized in that: The mass ratio of the biphasic calcium phosphate ceramic in the modified polyetheretherketone in step (3) is 10%-20%.

7. The method for preparing the skull implant according to claim 5, characterized in that: The aperture specification of the printing nozzle is 0.1-1 mm.

8. The method for preparing the skull implant according to claim 7, characterized in that: The aperture specification of the printing nozzle is 0.2mm-0.6mm.

9. The method for preparing the skull implant according to claim 5, characterized in that: In step (3), the printing layer thickness of the skull implant is 0.1-0.3 mm.

10. The method for preparing the skull implant according to claim 9, characterized in that: In step (3), the printing layer thickness of the skull implant is 0.15-0.2 mm.

11. The method for preparing a skull implant according to claim 5, characterized in that: The extrusion ratio of the printing nozzle is 0.8-1.

12. The method for preparing the skull implant according to claim 1, characterized in that: The skull model is placed at an angle of ≤45° between the skull model and the printing base plate in step (3). The print head is controlled to be perpendicular to the printing base plate and to move at a distance of ≥5 mm away from the printing base plate to generate an array of support columns.

13. The method for preparing the skull implant according to claim 12, characterized in that: The length of the support column is ≥1mm, and the width is ≥1mm.

14. The method for preparing the skull implant according to claim 12, characterized in that: In step (3), the bottom filling rate of the support column is controlled to be 40%-60%, and the top filling rate is controlled to be 80%-100%.

15. The method for preparing the skull implant according to any one of claims 12 to 14, characterized in that: The printing nozzle performs reciprocating printing in one direction, so that the distance between the top surface of the support column and the bottom surface of the skull model is 0.3-0.5 mm, thereby completing the printing of the support column.

16. The method for preparing the skull implant according to claim 1, characterized in that: In step (3), the skull implant is printed, the solid part is filled with a filling rate of 60%-100%, the overlapping rate of the outline filling is 30%-50%, and the number of shells is 1-3 layers.

17. The method for preparing the skull implant according to claim 16, characterized in that: The porous part in step (3) is formed by using a three-dimensional porous array design model in combination with a filling strategy and material feed control. The filling strategy is a path planning for 3D printing material accumulation, so that the material accumulation path runs along the model of the porous structure design. The material feed control is a precise control of the extrusion feed and retraction of the material through a gear mechanism, and in combination with the path planning, the material is accurately accumulated on the porous designed structure.

18. The method for preparing a skull implant according to claim 1, characterized in that: In step (3), when the temperature of the printed object is 50-150° C., supports and burrs are removed.

19. The method for preparing a skull implant according to claim 18, characterized in that: In step (3), when the temperature of the printed object is 80-120° C., supports and burrs are removed.

20. A skull implant prepared by the method for preparing a skull implant according to any one of claims 1 to 19.

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