CN115715716A - Cranial implant and preparation method thereof - Google Patents

Abstract

The invention relates to a cranial implant and a method for making the same, comprising: establishing a three-dimensional defect model of a patient by a digital medical imaging technology, and carrying out customized design on a skull repairing system to obtain a skull embryonic form; designing a skull plate interface porous structure for a skull prototype, and generating a longitudinally penetrating pore structure vertical to a human body contact surface at the position of the skull in contact with the human body by a method of offset curved surface and array removal to obtain a skull model; 3D printing is carried out on the skull model, polyether-ether-ketone or modified polyether-ether-ketone is adopted, the temperature of a printing nozzle is 350-500 ℃, and the temperature of the thermal atmosphere of a printing chamber is 90-250 ℃. The cranial implant obtained by the preparation method is perfectly matched with the skull defect part of a patient, has smooth surface, can be tightly combined with human tissues, and is beneficial to postoperative bone regeneration, so that the problems of poor prosthesis adaptability, postoperative toxic reaction, poor fusion, long-term implantation failure risk and the like existing in skull plate replacement surgery are solved.

Description

A kind of skull implant and preparation method thereof

technical field

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

Background technique

Millions of surgeries are performed worldwide each year for skull plate replacements. Autograft and allograft are the gold standard for the treatment of skull defects; however, due to insufficient supply of bone source and difficulty in adapting to shape, other biomaterials are widely used in the field of surgery to replace the shortage of autologous or allogeneic bone source, among which titanium Metal materials, polyetheretherketone (PEEK) materials, and bioceramic materials have been widely used in clinical practice for skull defect prostheses made of materials such as machining, injection molding, and sintering. The product still has the following disadvantages:

1. It is difficult for metal skull implants to meet the 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 loss of surrounding bone. In addition, metal-based implants may corrode surrounding tissues and cause cytotoxic responses by releasing metal ions into the host.

2. PEEK material exhibits strong hydrophobicity, and it is difficult to form good bone tissue adhesion on the surface interface. At present, the main way to solve this problem is surface modification, but the modification process of surface modification can easily lead to changes in the properties of the matrix material, and surface modification coatings and other technologies have poor bonding performance with the matrix, and are easy to fall off, resulting in long-term implantation of products after surgery. risk of failure.

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

4. The current manufacturing methods are mainly machining, injection molding and other material reduction methods. There are problems such as limited raw material specifications, a large amount of material waste caused by cutting processing, single nature of molding samples, expensive fixtures and molds, and long cycle times. , unable to adapt to complex medical batch manufacturing of complex customized products.

5. The surface of the existing machined and injection-molded products is smooth, which also easily causes osteoblasts to be difficult to adhere, differentiate, and proliferate, and lacks space for bone tissue regeneration, making it difficult to achieve bone regeneration and good interface integration.

Contents of the invention

The purpose of the present invention is to overcome the existing problems of the existing skull implants, and provide a preparation method of the skull implants. The matching degree of the surrounding tissue perfectly matches the physiological curvature and size of the patient's maxillofacial, and the porous structure ensures that the implant is not easy to slip off and loosen after implantation, and can achieve a tight combination with the surrounding bone tissue. At the same time, ensure that the support is easy to remove, and it is not easy to cause residues on the solid part of the part.

The specific plan is as follows:

A preparation method for a skull implant, comprising the following steps:

(1) Establish a three-dimensional defect model of the patient through digital medical imaging technology, and conduct a customized design of the skull repair system to obtain the prototype of the skull;

(2) Carry out the porous structure design of the skull plate interface on the skull prototype, and generate a pore structure by offsetting curved surfaces and array removal methods at the contact surface between the skull and the human body to obtain a skull model;

(3) 3D printing is performed on the skull model, using polyetheretherketone or modified polyetheretherketone material, the temperature of the printing nozzle is 350°C-500°C, the temperature of the hot atmosphere in the printing chamber is 90°C-250°C, according to Print in the following order:

First print the support column for supporting the skull implant, the support column is determined according to the placement angle of the skull model, and the support column is formed at the gap between the skull model and the printing base after placement;

Then, print the cranial implant on the support column, adopt the method of filling and printing the skull outline layer by layer, that is, first print the skull outline, and then fill between the outlines to form a solid part and a porous part, and the porous part A plurality of array holes are combined to form a ring on the periphery of the solid part; during the printing process, the printing material is extruded through the printing nozzle to perform a retraction action, and the retraction speed of the retraction action is 1500-1800mm/min, When withdrawing, lift the nozzle by 0.2-1mm, withdraw by 4-7mm, and then extrude compensation by 0.2-1mm after withdrawing, and the sliding distance is 0.1-1mm;

Finally, the supports and burrs of the printed object were removed to obtain a skull implant with a solid interior and a porous bone interface.

Further, 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 1mm; the establishment of the three-dimensional defect model adopts the algorithm of image threshold segmentation, sets the gray threshold, and the skull The defect model area is separated, and a 3D data format file composed of triangular mesh structures is generated.

Further, the customized design of the skull repair system in step (1) includes, by performing symmetrical mirroring processing on the 3D model data of the patient's defect part, filling the intact part into the corresponding defect region in a mirroring manner, and Through the combination of Boolean operation, translation, rotation and redesign, the matching of the edge and position of the skull is completed.

Further, the pore structure in step (2) has a pore diameter range of 200-2000um, a pore wall thickness of 300um-800um, and a pore longitudinal depth of 1-2mm.

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

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

Optionally, the thickness of the printing layer is 0.1-0.3mm, preferably 0.15-0.2mm;

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

Further, the placement angle of the skull model in step (3) is such that the included angle between the skull model and the printing base is ≤45°, and the direction of the printing nozzle is controlled to be perpendicular to the printing base and away from the printing base. The bottom plate is moved at a distance of ≥5 mm to generate the support columns in an array, preferably, the length of the support columns is ≥1 mm and the width is ≥1 mm;

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

Further, the printing nozzle prints reciprocally 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.

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

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

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

The present invention also protects the skull implant prepared by the preparation method of the skull implant.

Beneficial effect:

In the present invention, the three-dimensional defect model of the patient is established through digital medical imaging technology, and the customized design of the skull repair system is carried out to obtain the prototype of the skull, which can better match the shape of the patient's skull. As a printing material, it can accelerate bone exchange after implantation, improve the healing speed of patient tissues, and solve the problem of bone loss caused by interface contact with metal skull implants and toxic reactions caused by the release of metal ions.

Furthermore, the present invention designs the porous structure of the skull plate interface on the skull prototype, and generates a pore structure, that is, a hollow part, which can be used for bone ingrowth after surgery, through offset curved surfaces and array removal methods at the contact surface between the skull and the human body. Provide space, accelerate bone exchange, improve the healing speed of patient tissues, and improve the postoperative recovery effect.

Furthermore, the present invention combines the solid part and the hollow part by layer printing to obtain an excellent texture structure, which can effectively promote the adhesion, differentiation and proliferation of osteoblasts, and improve the effect of skull repair.

In short, the skull implant obtained by the preparation method of the present invention perfectly matches the patient's skull defect, has a smooth surface, and can be closely combined with human tissue, which is beneficial to postoperative bone regeneration, thereby solving the problem of skull plate replacement surgery. Poor adaptability, postoperative toxicity, long-term implantation failure risk and other problems have excellent market application prospects.

Description of drawings

In order to illustrate the technical solution of the present invention more clearly, the accompanying drawings will be briefly introduced below. Apparently, the accompanying drawings in the following description only relate to some embodiments of the present invention, rather than limiting the present invention.

Fig. 1 is the process flow chart that an embodiment of the present invention provides;

Fig. 2 is an image grayscale threshold segmentation diagram provided by an embodiment of the present invention;

Fig. 3 is a design diagram of a personalized skull plate provided by an embodiment of the present invention;

Fig. 4 is a schematic diagram of a solid part of a skull implant provided by an embodiment of the present invention;

Fig. 5 is a schematic diagram of the porous part of the skull implant provided by one embodiment of the present invention;

Fig. 6 is an offset curved surface view of a skull implant provided by an embodiment of the present invention;

Fig. 7 is a schematic diagram of a porous array in a skull implant provided by an embodiment of the present invention;

Fig. 8 is a graph after conversion of triangular patch data provided by an embodiment of the present invention;

Fig. 9 is a support column design and slice preview of a skull implant provided by an embodiment of the present invention;

Fig. 10 is a schematic diagram of an internal filling structure in a skull implant provided by an embodiment of the present invention;

Fig. 11 is a schematic diagram of a solid part provided by an embodiment of the present invention for non-return pumping and empty walking;

Fig. 12 is a schematic diagram of non-return evacuation of the porous part provided by an embodiment of the present invention;

Fig. 13 is a finished skull implant provided by an embodiment of the present invention.

Detailed ways

Preferred embodiments of the present invention will be described in more detail below. Although preferred embodiments of the present invention are described below, it should be understood that the present invention can be embodied in various forms and should not be limited by the embodiments set forth herein. If no specific technique or condition is indicated in the examples, it shall be carried out according to the technique or condition described in the literature in this field or according to the product specification. The reagents or instruments used were not indicated by the manufacturer, and they were all commercially available conventional products. In the following examples, if not explicitly stated, "%" refers to percentage by weight.

Example 1

A method for preparing a skull implant. The process flow is shown in Figure 1. The main steps include: based on the clinical needs of the medical institution, reconstructing the three-dimensional defect model of the patient through digital medical imaging technology and performing a customized design of the skull repair system. Add the corresponding process support structure, set the optimized melt extrusion deposition process parameters, and process the debugged printing model data by layer-by-layer slicing and transfer to the device, using polyether ether ketone (PEEK) and biphasic phosphoric acid Calcium (BCP) physically mixed and filled filaments are used for 3D printing. After molding, the supports and burrs are removed, and finally a customized skull implant with a solid interior and a porous bone interface is formed.

Specifically include the following steps:

(1) Establish a three-dimensional defect model of the patient through digital medical imaging technology, and conduct a customized design of the skull repair system to obtain the prototype of the skull;

(2) Carry out the porous structure design of the skull plate interface on the skull prototype, and generate a longitudinally penetrating pore structure perpendicular to the human body contact surface through the method of offset curved surface and array removal at the contact surface of the skull and human body, and obtain the skull model ;

(3) Perform 3D printing on the skull model, using polyether ether ketone or modified polyether ether ketone, the temperature of the printing nozzle is 350°C-500°C, the temperature of the hot atmosphere in the printing chamber is 90°C-250°C, according to the following Print in order:

Firstly, print the support column for supporting the skull implant, the support column is determined according to the placement angle of the skull model, the support column is formed in the gap between the skull model and the printing base after the placement, and the control The bottom filling rate of the support column is 40%-60%, and the top filling rate is 80%-100%;

Then, the cranial 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 pore structure are formed by filling between the contours. The solid part Filling is carried out with a filling rate of 60%-100%, the overlapping rate of outline and filling is 30%-50%, and the number of shells is 1-3 layers to obtain a molding;

Finally, the supports and burrs were removed from the molding to obtain a skull implant with a solid interior and a porous bone interface.

Each step is described in detail below:

In step (1), the slice thickness of the patient's thin-slice CT scan image data should be no more than 1 mm, preferably 0.1-0.5 mm, so as to obtain enough data for the next step to establish a model.

The three-dimensional defect model, through the image threshold segmentation algorithm, sets the appropriate gray threshold as shown in Figure 2, separates the skull defect model area, and produces a three-dimensional data format with a triangular patch structure.

The customized design of the skull repair system is mainly through symmetrical processing of the 3D model data of the patient's defect part, filling the intact part into the corresponding defect region in the form of a mirror image, and performing Boolean operations, translation, rotation, redesign, etc. The edge and position matching of customized products can be completed in this way, as shown in Figure 3.

In step (2), the porous structure of the skull plate interface is designed for the skull prototype, and a regular porous structure suitable for bone ingrowth is designed at the bone interface of the skull plate. And the method of array removal generates a 1-2mm longitudinally deep penetrating pore structure, the porous structure is a square opening, the pore diameter range is between 200-2000um, and the thickness of the pore wall is between 300um-800um. The overall structure is shown in Figure 4～ 8.

In step (3), 3D printing is performed on the skull model, using polyetheretherketone (PEEK) or modified polyether ether ketone, preferably using modified polyether ether ketone, and using bioceramic biphasic calcium phosphate (BCP) The polyether ether ketone is modified 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 of BCP can be in the range of 0%-50%, preferably in the range of 10%-20%, so as to obtain excellent comprehensive properties of mechanical and biocompatibility.

The temperature of the print nozzle is 350°C-500°C, and the temperature of the thermal atmosphere in the printing chamber is 20°C-250°C. Under the above temperature, the temperature of the print head and the thermal atmosphere of the chamber is conducive to ensuring stable crystallization during the printing process and improving the interlayer bonding of the product. performance, preventing delamination caused by poor bonding between layers that is common in FDM printing methods.

Firstly, the support column for supporting the skull implant is printed, the support design of the skull model, and the support is generated when the overhang angle is ≤45°, that is, the included angle between the skull model and the printing base plate is ≤45°. The printing nozzle performs reciprocating printing in one direction, 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, and the dense support layer on the top surface of the support column is 1-3 layers. The filling rate of the top surface of the support column is 80%-100%, so as to ensure the integrity and smoothness of the cranial repair product at the support interface and to have better detachability, as shown in Figure 9.

Preferably, the placement angle of the skull model is based on the largest projected area of the base plate, and moves 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 ≥1 mm.

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

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 osseointegration interface. It should be noted that the solid part needs to have a pore structure. This part of the pore structure is mainly for drainage, to prevent the risk of implant failure caused by fluid accumulation at the skull repair site, and it can also be used for dural suspension threading.

The solid part of the skull implant is filled with a filling rate of 60%-100%, the filling strategy is in the form of a 45°/45° grid, the overlapping rate of the shell and the fill 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.

Because the main body of the skull plate has high requirements on surface finish and integrity, filling + multi-layer contour molding can be used to ensure the quality of the outer surface, as shown in Figure 10. Melt extrusion 3D printing FDM technology (full name Fused Deposition Modeling, Fused Deposition Modeling) generally transmits materials through gears, and achieves precise molding of solid and porous structures by controlling the extrusion and retraction of materials.

The printing of the porous structure of the skull implant needs to control material leakage, as shown in Figure 11 and Figure 12. The extruded wire is withdrawn in stages, that is, the withdrawal speed is 1500-1800mm/min, and the nozzle is raised by 0.2 when withdrawing. -1mm, retract 4-7mm, squeeze out after retracting to compensate 0.2-1mm, slide distance 0.1-1mm. The retraction can avoid the overflow and drawing of the material when the material moves at the transition position of the porous structure during the printing process, and ensure the permeability of the porous structure in the XY direction.

Finally, remove the supports and burrs from the molded object. After printing, the sample can be removed from the bottom plate of the equipment at about 50-150°C, preferably at about 100°C. The knives are removed one by one to form the final product.

Example 2

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

Establish a three-dimensional defect model of the patient through digital medical imaging technology, and carry out the customized design of the skull repair system to obtain the prototype of the skull; design the porous structure of the skull plate interface on the prototype of the skull, and use the offset curved surface on the interface between the skull and the human body And the method of array removal to generate a longitudinally penetrating pore structure perpendicular to the human body contact surface to obtain a skull model. The length of the skull implant is 94mm and the width is 88mm. There are pores on the side of the skull implant around the bone joint, the length and width of the square porous structure: 0.6mm, the wall thickness of the holes is 0.6mm, arranged in a matrix, and the depth is 2mm.

The designed skull implant model is used for printing, and the mixture of polyether ether ketone and biphasic calcium phosphate ceramics (20wt%) is used as the printing material. The diameter of the printing nozzle is 0.4mm, the extrusion ratio is 0.9, and the printing temperature is 485 °C, the ambient temperature is 230 °C, and the layer height is 0.2mm. The cranial implant includes a solid part and a porous part, wherein the solid part performs empty walking without retraction, and the porous part performs retraction action. The retraction speed of the retraction action is 1500mm/min, and the nozzle is lifted by 0.5mm during withdrawal. Withdraw 5mm, then extrude to compensate 0.5mm, slide distance 0.5mm.

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

Then print the skull implant, the solid part of the skull implant has a filling rate of 90%, the filling angle is 45°/45°, the overlap rate of the shell and filling is 30%, and the number of shells is set to 1 layer.

After printing, when the temperature was lowered to 100°C, the part and support were removed from the base plate and the support was removed from the part at the same time to obtain a smooth skull implant.

Example 3

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

Establish a three-dimensional defect model of the patient through digital medical imaging technology, and carry out the customized design of the skull repair system to obtain the prototype of the skull; design the porous structure of the skull plate interface on the prototype of the skull, and use the offset curved surface on the interface between the skull and the human body And the method of array removal to generate a longitudinally penetrating pore structure perpendicular to the human body contact surface to obtain a skull model. The length of the skull implant is 94mm and the width is 88mm. There are pores on the side of the skull implant around the bone joint, the length and width of the square porous structure: 0.6mm, the wall thickness of the holes is 0.6mm, arranged in a matrix, and the depth is 2mm.

The designed skull implant model is used for printing, and the mixture of polyether ether ketone and biphasic calcium phosphate ceramics (content 10wt%) is used as the printing material. The diameter of the printing nozzle is 0.2mm, the extrusion ratio is 0.9, and the printing temperature is 380 ℃, ambient temperature 120 ℃, layer height 0.2mm. The cranial implant includes a solid part and a porous part, wherein the solid part performs empty walking without retraction, and the porous part performs retraction action. The retraction speed of the retraction action is 1700mm/min, and the nozzle is lifted by 0.2mm during withdrawal. Withdraw 4mm, then extrude to compensate 0.2mm, and slide distance 0.2mm.

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

Then print the skull implant, the solid part of the skull implant has a filling rate of 60%, the filling angle is 45°/45°, the overlap rate of the shell and filling is 30%, and the number of shells is set to 1 layer.

After printing, when the temperature was lowered to 100°C, the part and support were removed from the base plate and the support was removed from the part at the same time to obtain a smooth skull implant.

Example 4

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

Establish a three-dimensional defect model of the patient through digital medical imaging technology, and carry out the customized design of the skull repair system to obtain the prototype of the skull; design the porous structure of the skull plate interface on the prototype of the skull, and use the offset curved surface on the interface between the skull and the human body And the method of array removal to generate a longitudinally penetrating pore structure perpendicular to the human body contact surface to obtain a skull model. The length of the skull implant is 94mm and the width is 88mm. There are pores on the side of the skull implant around the bone joint, the length and width of the square porous structure: 0.6mm, the wall thickness of the holes is 0.6mm, arranged in a matrix, and the depth is 2mm.

Print with the designed skull implant model, the mixture of polyetheretherketone and biphasic calcium phosphate ceramics (content 20wt%) is used as the printing material. The diameter of the printing nozzle is 1mm, the extrusion ratio is 0.9, and the printing temperature is 410°C , the ambient temperature is 150°C, and the layer height is 0.2mm. The skull implant consists of a solid part and a porous part, wherein the solid part performs empty walking without retraction, and the porous part performs retraction action. The withdrawal speed of the withdrawal action is 1800mm/min. When withdrawing, the nozzle is lifted by 1mm, and the retraction Pump 6mm, then squeeze out to compensate 1mm, and the sliding distance is 0.8mm.

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

Then print the skull implant, the solid part of the skull implant has a filling rate of 100%, the filling angle is 45°/45°, the overlap rate of the shell and filling is 50%, and the number of shells is set to 1 layer.

After printing, when the temperature was lowered to 100°C, the part and support were removed from the base plate and the support was removed from the part at the same time to obtain a smooth skull implant.

Example 5

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

Establish a three-dimensional defect model of the patient through digital medical imaging technology, and carry out the customized design of the skull repair system to obtain the prototype of the skull; design the porous structure of the skull plate interface on the prototype of the skull, and use the offset curved surface on the interface between the skull and the human body And the method of array removal to generate a longitudinally penetrating pore structure perpendicular to the human body contact surface to obtain a skull model. The length of the skull implant is 94mm and the width is 88mm. There are pores on the side of the skull implant around the bone joint, the length and width of the square porous structure: 0.6mm, the wall thickness of the holes is 0.6mm, arranged in a matrix, and the depth is 2mm.

The designed skull implant model is used for printing, and the mixture of polyether ether ketone and biphasic calcium phosphate ceramics (content 20wt%) is used as the printing material. The diameter of the printing nozzle is 0.5mm, the extrusion ratio is 0.9, and the printing temperature is 450 ℃, the ambient temperature is 90 ℃, and the layer height is 0.2mm. The cranial implant includes a solid part and a porous part, wherein the solid part performs empty walking without retraction, and the porous part performs retraction action. The retraction speed of the retraction action is 1600mm/min, and the nozzle is lifted by 0.8mm during withdrawal. Withdraw 4mm, then extrude to compensate 0.4mm, and slide distance 0.4mm.

Print the support column first, and make a solid support along the bottom outer contour of the skull implant. The minimum height of the support is 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°, the horizontal offset is 0.5mm, and the filling rate of the support bottom is 60%; the dense support layer on the top surface has 3 layers, and the filling rate is 100%.

Then print the skull implant, the solid part of the skull implant has a filling rate of 90%, the filling angle is 45°/45°, the overlap rate of the shell and filling is 40%, and the number of shells is set to 1 layer.

After printing, when the temperature was lowered to 100°C, the part and support were removed from the base plate and the support was removed from the part at the same time to obtain a smooth skull implant.

Comparative example 1

This embodiment refers to Embodiment 2. Under other conditions being the same, after adjusting the ambient temperature inside the 3D printing equipment chamber from 230°C to <80°C, the color of the 3D printed product is dark and transparent. State PEEK material is in an amorphous state, and the strength of the final product is much weaker than that of crystalline products. The product printing process has obvious delamination and warping deformation. As the 3D printing process progresses, the product warping deformation will become more and more serious until the printing process cannot continue.

Comparative example 2

This embodiment refers to Example 2. Under the same conditions as other conditions, the porous part is retracted. The retraction speed of the retraction is 1500mm/min, and the retraction is 5mm. The porous part is changed to no retraction. Or perform retraction, but the retraction speed of the retraction action is less than 1000mm/min, and the retraction is 1mm, because at the beginning and end of the porous structure, the feed rate of the material (extrusion & retraction) and the feed speed (squeeze Out & back) does not match the printing rate, resulting in obvious overflow of the material at the beginning and end, clogging of the opening space of the porous part, burrs and other phenomena, and the connectivity of the porous structure is affected.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention. These simple modifications All belong to the protection scope of the present invention.

In addition, it should be noted that the various specific technical features described in the above specific implementation manners may be combined in any suitable manner if there is no contradiction. In order to avoid unnecessary repetition, various possible combinations are not further described in the present invention.

In addition, various combinations of different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

Claims (10)

1. A method of preparing a cranial implant, comprising: the method comprises the following steps:

(1) Establishing a three-dimensional defect model of a patient by a digital medical imaging technology, and carrying out customized design on a skull repairing system to obtain a skull embryonic form;

(2) Designing a skull-bone plate interface porous structure for the skull prototype, and generating a pore structure at the contact surface part of the skull and a human body by a method of offset curved surface and array removal to obtain a skull model;

(3) 3D printing is carried out on the skull model, a polyether-ether-ketone or modified polyether-ether-ketone material is adopted, the temperature of a printing spray head is 350-500 ℃, the temperature of a hot atmosphere of a printing chamber is 90-250 ℃, and printing is carried out according to the following sequence:

firstly, printing a support column for supporting a cranial implant, wherein the support column is determined according to the placement angle of the cranial model, and the support column is formed at a gap between the placed cranial model and a printing bottom plate;

then, printing a cranial implant above the supporting column, and adopting a mode of filling and skull contour layer by layer printing and molding, namely firstly printing the skull contour, and then filling and forming a solid part and a porous part between the contours, wherein the porous part is formed by combining a plurality of arrayed holes and forms a ring shape on the periphery of the solid part; in the printing process, a printing material is extruded by a printing nozzle and then is pumped back, the pumping back speed of the pumping back action is 1500-1800mm/min, the nozzle is lifted by 0.2-1mm during pumping back, the pumping back is 4-7mm, the extrusion compensation is carried out again by 0.2-1mm after pumping back, and the sliding distance is 0.1-1mm;

and finally, removing the support and the burr of the printing object to obtain the cranial implant with a solid inner part and a porous bone-knitting surface interface.

2. The method of preparing a cranial implant according to claim 1, wherein: CT scanning is adopted in the digital medical imaging technology in the step (1), and the thickness of a layered scanning data layer is not more than 1mm; the three-dimensional defect model is established by setting a gray threshold through an algorithm of image threshold segmentation, dividing a skull defect model region, and generating a three-dimensional data format file consisting of a triangular patch structure.

3. Method for the preparation of a cranial implant according to claim 1 or 2, characterized in that: the customized design of the skull repairing system in the step (1) comprises the steps of carrying out symmetrical mirror image processing on 3D model data of the defect part of the patient, filling the intact area part into the corresponding defect area in a mirror image mode, and completing the edge and position matching of the skull in a mode of combining Boolean operation, translation, rotation and redesign.

4. The method of making a cranial implant according to claim 1, wherein: in the step (2), the pore diameter range of the pore structure is between 200 and 2000um, the thickness of the pore wall is between 300um and 800um, and the longitudinal depth of the pore diameter is 1 to 2mm.

5. The method of preparing a cranial implant according to claim 1, wherein: the modified polyetheretherketone in the 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%;

optionally, the aperture specification of the printing nozzle is 0.1-1mm, preferably 0.2-0.6 mm;

optionally, the print layer has a thickness of 0.1 to 0.3mm, preferably 0.15 to 0.2mm;

optionally, the extrusion magnification of the printing nozzle is 0.8-1.

6. The method of preparing a cranial implant according to claim 1 or 5, wherein: in the step (3), the placing angle of the skull model is that the included angle between the skull model and the printing bottom plate is not more than 45 degrees, the printing spray head is controlled to move towards the direction perpendicular to the printing bottom plate and at a distance of not less than 5mm away from the printing bottom plate to generate the array-type support pillars, preferably, the length of each support pillar is not less than 1mm, and the width of each support pillar is not less than 1mm; 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%.

7. The method of preparing a cranial implant according to claim 6, wherein: and the printing nozzle performs unidirectional reciprocating printing, so that the distance between the top surface of the support column and the bottom surface of the skull model is 0.3-0.5mm, and the printing of the support column is completed.

8. The method of making a cranial implant according to claim 1, wherein: printing the cranial implant in the step (3), wherein the solid part is filled by adopting a 60-100% filling rate, the overlapping rate of contour filling is 30-50%, and the number of shells is 1-3 layers;

optionally, the porous part is molded by matching a three-dimensional porous array design model with a filling strategy and material feeding control, the filling strategy is a path plan for 3D printing material accumulation, the accumulation path of the material runs along the model designed by the porous structure, the material feeding control is precise control of extrusion feeding and back pumping of the material through a gear mechanism, and the material is accurately accumulated on the structure designed by the porous structure by matching with the path plan.

9. The method of making a cranial implant according to claim 1, wherein: in the step (3), the support and the burr are removed when the temperature of the printing object is 50-150 ℃, preferably 80-120 ℃.

10. A cranial implant prepared by the method of preparing a cranial implant according to any one of claims 1-9.

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