3D printing type skull protection cap capable of enhancing protection

Abstract

The invention relates to 3D printing medical equipment. The 3D printing type skull protective cap capable of enhancing protection comprises a protective cap body which is formed in a 3D printing mode and matched with a skull defect part of a patient, and a soft cushion arranged between the edge of the bottom of the protective cap body and the head tissue of the human body. The soft cushion is also formed in a 3D printing mode. According to the protective cap, the soft cushion is additionally arranged below the protective cap body, the stress condition of the contact face with the head soft tissue of the human body can be well improved through the soft cushion, and the installation stability and the protection reliability of the protective cap body are improved. Through the soft cushion, the processing error gap objectively existing between the head soft tissue of the human body and the protective cap main body can be filled, the contact effectiveness between the head soft tissue of the human body and the protective cap main body is ensured, the condition of abnormal stress or stress concentration is improved, and the risk that the protective cap main body is out of position when subjected to external force is reduced.

Description

Technical Field

[0001] The present invention relates to the field of 3D printing medicine, and particularly to a 3D printed skull protection cap with enhanced protection. Background Art

[0002] In recent years, with the rapid popularization and application of 3D printing technology in the medical field, more and more hospitals and medical research institutions have gradually started to adopt 3D printing to form various customized instruments or protective devices to meet the needs of personalized and customized medicine. The skull protection cap is a protective device for severe cranial injuries with skull defects, which realizes external protection of intracranial tissues by wearing the protective device. Wearing the skull protection cap can provide anti-impact protection for intracranial tissues, make the intracranial tissues full, and quickly restore to the anatomical shape before injury, which is an important transitional stage for subsequent skull repair.

[0003] At present, the skull protection caps manufactured by traditional methods are not only expensive and have a long customization cycle, but also cannot truly and perfectly match the shape of the patient's cranial defect. They not only have insufficient protection, but also have poor aesthetics after wearing, and increasingly do not meet the development needs of modern medicine. This is mainly because in the production and manufacturing process of the skull protection cap prepared by traditional methods, only isolated parameters such as the shape of the protection cap and the position of the protection cap are mainly considered, without systematic mechanical property analysis. Its anti-bending and anti-torsion properties cannot be effectively guaranteed after wearing, resulting in certain deficiencies in the reliability of its protection after wearing; reducing the risk of hidden dangers during the wearing of the skull protection cap. Summary of the Invention

[0004] The purpose of the present invention is to provide a 3D printed skull protection cap with enhanced protection that has good protection performance and stable and reliable force.

[0005] To achieve the above-mentioned invention purpose, the technical solution adopted by the present invention is: a 3D printed skull protection cap with enhanced protection, including a protection cap main body formed by 3D printing and matching with the skull defect part of the patient, and a soft pad arranged between the bottom edge of the protection cap main body and the human head tissue; the soft pad is also formed by 3D printing.

[0006] Preferably, it further includes a fixing component for fixing the protection cap main body on the patient's head.

[0007] Preferably, the fixing component is a net bag worn on the patient's head.

[0008] Preferably, the fixing component is an elastic strap arranged on the edge of the protection cap main body.

[0009] Preferably, a beautifying layer is further provided on the outer surface of the protection cap body. The beautifying layer is a layer of flexible cloth adhesively fixed on the outer surface of the protection cap body and artificial hair pasted on the flexible cloth.

[0010] Preferably, an installation groove extending circumferentially along the soft pad is provided at a position on the edge of the bottom of the protection cap body opposite to the soft pad, and the soft pad is clamped in the installation groove.

[0011] Preferably, the manufacturing method of the protection cap body and the soft pad includes the following steps:

[0012] S1. Obtain the three-dimensional models of the cranial part before and after the operation of the patient;

[0013] S2. Smooth the surface defects of the three-dimensional models of the cranial part before and after the operation; generate corresponding NURBS surface models;

[0014] S3. Taking the skull defect range on the three-dimensional model of the cranial part after the operation as a reference, cut a block from the three-dimensional model of the cranial part before the operation as the protection cap model. The range of the protection cap model is determined by being able to cover the skull defect range after the operation, and adjust the thickness of the protection cap model;

[0015] S4. Align the cut protection cap model to the three-dimensional model of the cranial part after the operation, and reserve an annular gap for installing the soft pad between the bottom of the edge of the protection cap model and the human head soft tissue;

[0016] S5. Generate a soft pad model according to the shape of the annular gap. The soft pad model, the protection cap model and the three-dimensional model of the cranial part after the operation together form a three-dimensional model set of the cranial pad cap; smooth the surface defects of the three-dimensional model set of the cranial pad cap, and generate corresponding NURBS surface models;

[0017] S6. Import the smoothed three-dimensional model set of the cranial pad cap into Ansys software in X_T format, and perform finite element stress analysis on the three-dimensional model set of the cranial pad cap; and adjust the soft pad model according to the results of the finite element stress analysis to determine the optimization method of the soft pad model in the three-dimensional model set of the cranial pad cap;

[0018] S7. Import the protection cap model and the soft pad model of the optimized and adjusted three-dimensional model set of the cranial pad cap into a 3D printing device and form them by 3D printing.

[0019] The beneficial effects of the present invention are mainly reflected in:

[0020] 1. By adding a soft pad under the protection cap body, the soft pad can better improve the stress condition of the contact surface with the human head soft tissue, and enhance the installation stability and protection reliability of the protection cap body.

[0021] 2. The soft pad can fill the objectively existing machining error gap between the human head soft tissue and the main body of the protective cap, ensuring the effectiveness of the contact between the human head soft tissue and the main body of the protective cap, improving the abnormal stress or stress concentration situation, and reducing the risk of dislocation of the main body of the protective cap when subjected to external forces.

[0022] 3. The overall structure is compact and simple, which is conducive to reducing the overall manufacturing cost. The 3D printing method can greatly improve the production speed, which has a positive effect on reducing medical costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the three-dimensional model of the cranial part of the patient after the operation of the present invention;

[0024] Figure 2 It is a schematic diagram of the protective cap model of the present invention;

[0025] Figure 3 It is a schematic diagram of the soft pad model of the present invention;

[0026] Figure 4 It is a schematic diagram of the three-dimensional model set of the cranial pad cap of the present invention;

[0027] Figure 5 It is a comparison image of a certain patient treated with the cranial protective cap of the present invention;

[0028] Figure 6 It is the Von-Mises stress nephogram of the head and the cranial protective cap without the soft pad;

[0029] Figure 7 It is the Von-Mises stress nephogram of the head and the cranial protective cap with the soft pad. DETAILED DESCRIPTION OF THE INVENTION

[0030] The present invention discloses a 3D printing type cranial protective cap with enhanced protection, which mainly includes a main body of the protective cap formed by 3D printing and matching with the cranial defect part of the patient, and a soft pad arranged between the bottom edge of the main body of the protective cap and the human head soft tissue; the soft pad is also formed by 3D printing. In the present invention, the shape of the main body of the protective cap can be Figure 2 with reference to the 3D printed entity of the protective cap model 2 in Figure 3 and the shape of the soft pad can be with reference to the 3D printed entity of the soft pad model 3 in

[0031] The 3D printed main body of the protective cap and the soft pad are prepared through a finite element stress analysis process, with better overall protection performance and better installation reliability, and can effectively reduce the risks during wearing. The specific preparation method is detailed below.

[0031] By adding a soft pad, the soft pad can better improve the stress condition of the contact surface with the soft tissues of the human head, enhance the stability of the installation of the main body of the protective cap and the reliability of protection. At the same time, the soft pad can fill the objectively existing machining error gap between the soft tissues of the human head and the main body of the protective cap, ensure the effectiveness of the contact between the soft tissues of the human head and the main body of the protective cap, improve the abnormal stress or stress concentration, and reduce the risk of dislocation of the main body of the protective cap when subjected to external forces.

[0032] However, for the skull protective cap described in the present invention, in order to facilitate wearing, a fixing component is often also provided, and the fixing component is used to fix the main body of the protective cap on the patient's head. There are many specific forms or structural types of the fixing component. For example, the fixing component is a net bag worn on the patient's head, or the fixing component is an elastic strap provided on the edge of the main body of the protective cap. The fixing component is usually installed and used separately in the later stage after the skull protective cap is processed.

[0033] For some patients with high requirements for aesthetics, the present invention can also provide a beautifying layer on the outer surface of the main body of the protective cap. The beautifying layer is a layer of flexible cloth pasted and fixed on the outer surface of the main body of the protective cap, and a simulation hair pasted on the flexible cloth. By adding the beautifying layer, the overall appearance of the protective cap can fit the appearance of the normal human skull, reducing the psychological burden of the patient when wearing. In addition, since the present invention is provided with a soft pad, in order to ensure the stability of the installation between the soft pad and the main body of the protective cap, and the convenience of installation, a better method can also be that an installation groove extending along the circumference of the soft pad is provided at a position opposite to the soft pad at the bottom edge of the main body of the protective cap, and the soft pad is clamped in the installation groove.

[0034] Compared with the traditional 3D printing preparation method, the present invention particularly discloses a preparation method of a skull protective cap based on finite element stress analysis, which specifically includes the following steps:

[0035] S1. Obtain the three-dimensional models 1 of the patient's skull before and after surgery. First, obtain the standard DICOM format data of the patient before and after surgery. The source of the standard DICOM format data can be one or a combination of CT, MRI, and X-ray. Import the standard DICOM format data into the MIMICS 21.0 software of Materialise company, and reconstruct the skull and head soft tissue data of the patient through the MIMICS 21.0 software, and generate the three-dimensional models 1 of the patient's skull before and after surgery. As Figure 1 shown, it is the three-dimensional model 1 of the patient's skull after surgery, and most of the skull defects are caused by the need to release intracranial pressure during the operation. The three-dimensional model 1 of the patient's skull before surgery can be regarded as the shape before the skull defect.

[0036] S2. Smooth the surface defects of the preoperative and postoperative cranial three-dimensional model 1 to generate the corresponding NURBS surface model. In practical applications, export the cranial three-dimensional model 1 processed in step S1 in STL format and import it into the Geomagic Wrap 2021 software under the American company Raindrop. Using this software, smooth the surface defects of the cranial three-dimensional model 1, such as filling holes on the surface, repairing nail-like structures, and smoothing non-smooth surfaces. After processing, generate the corresponding NURBS surface model after smoothing.

[0037] S3. Using the skull defect range on the postoperative cranial three-dimensional model 1 as a reference, cut a block from the preoperative cranial three-dimensional model 1 as the protection cap model 2. The range of the protection cap model 2 should be able to cover the postoperative skull defect range, and adjust the thickness of the protection cap model 2, usually 4 mm.

[0038] S4. Align the cut protection cap model 2 to the postoperative cranial three-dimensional model 1 to verify the reliability of its coverage of the skull defect range. Reserve an annular gap for installing the soft pad model 3 between the bottom of the edge of the protection cap model 2 and the human head soft tissue. The thickness of the annular gap is generally 2 mm, and the width can be set to about 0.8 - 1.2 cm.

[0039] S5. Then, generate the soft pad model 3 according to the shape of the annular gap. The soft pad model 3, the protection cap model 2, and the postoperative cranial three-dimensional model 1 together form a cranial pad cap three-dimensional model set. Perform an overall secondary smoothing process on the surface defects of the cranial pad cap three-dimensional model set to generate the corresponding NURBS surface model. The smoothing method is equivalent to the previous smoothing method, which is to use geomagic software to fill, repair, and smooth the surface defects of the cranial pad cap three-dimensional model set. According to the actual situation, multiple processing methods can be used alone or in combination. After processing, generate the corresponding NURBS surface model after smoothing, that is, the NURBS surface model of the cranial pad cap three-dimensional model set.

[0040] S6. Import the smoothed cranial pad cap three-dimensional model set into Ansys software in X_T format for finite element stress analysis of the cranial pad cap three-dimensional model set. Finally, adjust the soft pad model 3 according to the results of the finite element stress analysis to determine the optimization method of the soft pad model 3 in the cranial pad cap three-dimensional model set.

[0041] In this step, the specific processing method can be as follows:

[0042] S6.1 Material Assignment: In the Ansys software, material properties are assigned to each part in the 3D model set of the cranial pad cap (including anatomical structures such as the skull and human head soft tissues; implants such as the protection cap model 2 and the soft pad model 3). When assigning material properties, the material characteristics of each solid element can be regarded as isotropic, continuous, and uniform. The specific materials and corresponding parameters can be selected by referring to existing common materials.

[0043] S6.2 Mesh Division Setting: Since the 3D model set of the cranial pad cap has an irregular shape, the second-order tetrahedral mesh elements (C3D10 elements) are used to divide the protection cap model 2, the soft pad model 3, and the human head soft tissues. And the appropriate number of mesh elements is determined through mesh sensitivity inspection.

[0044] S6.3 Contact Pair Setting: The contact surface between the soft pad model 3 and the protection cap model 2 is set as a bonded contact, and the contact surface between the soft pad model 3 and the human head soft tissues is set as a non-separating contact. It is assumed that there is no relative displacement between the contact surfaces of the remaining solid parts in the 3D model set of the cranial pad cap, and they are still set as bonded contacts.

[0045] S6.4 Boundary and Load Condition Setting: Fix the position at the very bottom of the head in the 3D model set of the cranial pad cap, that is, the constraint, which means fixing the 6 degrees of freedom in the three-dimensional space of the lower part of the head (neck). Simulate by applying a force of 50 N in the axial direction and a torque of 1.5 N·m on the surface of the protection cap model 2 to simulate the four working conditions of the 3D model of the cranial pad cap bending to the left, bending to the right, rotating to the left, and rotating to the right. And record the stress distribution on the contact surface between the human head soft tissues and the soft pad model 3 in the 3D model set of the cranial pad cap.

[0046] S6.5 Repeat steps S6.1 - S6.4. Among them, adjust the material parameters assigned to the soft pad model 3 to be the same as those of the protection cap model 2, and set the contact surface between the soft pad model 3 and the human head soft tissues as a bonded contact to serve as the cranial cap model set without the soft pad model 3, and record the stress distribution on the contact surface with the human head soft tissues under the four working conditions of bending to the left, bending to the right, rotating to the left, and rotating to the right under the same load conditions (applying a force of 50 N in the axial direction and a torque of 1.5 N·m on the surface of the protection cap model 2).

[0047] S6.6 Comparison: Compare the contact surface stress distribution results of the corresponding recorded non-cushion model 3 skull cap model set and the skull cap three-dimensional model set, and use the decrease in stress peak as the basis for judging whether the soft cushion model 3 improves abnormal stress or stress concentration. If the stress peak is reduced and the stress is uniform, it means that the stress condition is positively affected by adding the soft cushion model 3; in some extremely special cases, the stress peak is not significantly reduced and the improvement of stress uniformity is not very obvious, which means that the protective film body 2 and the soft tissue of the human head are well matched, and the shape of the periphery of the skull defect makes it have good reliability even without adding the soft cushion model 3. In this case, the soft cushion can be omitted according to the wishes of the patient and the patient's family to reduce the overall cost. However, the probability of this situation is low. According to comprehensive statistics, in more than 98% of the cases, the stress condition is effectively improved after adding the soft cushion model 3. At the same time, the present invention can also use the decrease in the stress peak as a basis for optimizing the cushion model 3, that is, by giving different material properties to the cushion model 3 and appropriately adjusting its thickness parameters, etc., its own stress condition can be improved to a certain extent and its performance can be enhanced. After reaching an optimization plan, different cushion materials can be selected for subsequent preparation based on the patient's wishes.

[0048] S7. Import the optimized and adjusted protective cap model 2 and soft cushion model 3 of the skull cap three-dimensional model set into a 3D printing device, and shape them by 3D printing to obtain the protective cap body and soft cushion, which are then delivered to the patient for use.

[0049] Application examples:

[0050] like Figure 5 As shown in the figure, the patient, Mr. Luo, male, 58 years old, was admitted to the hospital due to a car accident. The diagnosis was: 1. Right temporal lobe cerebral contusion, 2. Right frontotemporal and parietal acute subdural hematoma, 3. Traumatic subarachnoid hemorrhage, 4. Left parietal fracture, 5. Left parietal scalp laceration. The patient was diagnosed after a CT scan when he was admitted to the hospital. On the same day, he underwent emergency general anesthesia for "right frontotemporal and parietal subdural hematoma removal + right temporal lobe partial resection + artificial dura mater repair + bone craniotomy decompression + debridement and suture". After the operation, he was hospitalized for a long time and was discharged after his condition improved.

[0051] Before discharge, the patient had a missing skull after surgery, the right frontal temporoparietal skin flap collapsed significantly, and the right side of the head lacked bone protection. If he fell accidentally, he would be at high risk of traumatic cerebral hemorrhage. Therefore, the present invention was used to protect the skull defect. The process of making the protective cap is consistent with the above method.

[0052] Finite element analysis: Compare the contact surface stress distribution results of the corresponding recorded non-cushion model 3 skull cap model set and the skull cap 3D model set, and use the decrease in the stress peak as a basis for determining whether the soft pad improves the abnormal stress or stress concentration of the skull cap.

[0053] The comparison data such as Figure 6 and 7 are shown in

[0054] Figure 6 In , different colors represent different stress conditions. The red area is the distribution of the maximum stress value range, and the blue area is the distribution of the minimum stress value range. Taking the working condition of bending down to the left as an example, stress concentration is likely to occur at the connection between the head and the protective cap. The stress peak value of the head is 0.052273 Mpa, and the stress peak value of the protective cap is 1.3591 Mpa.

[0055] Figure 7 In , different colors represent different stress conditions. The red area is the distribution of the maximum stress value range, and the blue area is the distribution of the minimum stress value range. Taking the working condition of bending down to the left as an example, the stress peak value of the head is 0.064354 Mpa, the stress peak value of the protective cap is 0.72995 Mpa, and the stress peak value of the soft pad is 0.049382 Mpa.

[0056] It can be seen from the comparison that compared with the model without a soft pad, although the stress peak value of the head has increased, the stress peak value of the protective cap has decreased extremely significantly. It can be seen that the stress peak value has decreased, indicating that the soft pad can significantly improve the stress concentration phenomenon generated between the skull protective cap and the head, and it is suitable for assembling a soft pad.

[0057] After the model is verified by finite element, it is prepared by 3D printing technology and placed on the patient. Since the protective cap fits and completely covers the skin flap of the patient's skull defect, the patient is relatively satisfied with the comfort, ease of wearing, and hardness of the protective cap.

Claims

1. A 3D printed skull cap with enhanced protection, characterized in that: It includes a protective cap body formed by 3D printing and matching with the defective part of the patient's skull, and a soft pad arranged between the bottom edge of the protective cap body and the soft tissue of the human head; the soft pad is also formed by 3D printing.

2. The 3D printed skull protection cap with enhanced protection according to claim 1, characterized in that: Also included is a fixing assembly, which is used to fix the protective cap body on the patient's head.

3. The 3D printed skull cap with enhanced protection according to claim 2, characterized in that: The fixing component is a net bag worn on the patient's head.

4. The 3D printed skull cap with enhanced protection according to claim 3, characterized in that: The fixing component is an elastic band arranged on the edge of the protective cap body.

5. The 3D printed skull cap with enhanced protection according to claim 4, characterized in that: The outer surface of the protective cap body is also provided with a beautifying layer, which is a layer of flexible cloth pasted and fixed on the outer surface of the protective cap body, and simulated hair pasted on the flexible cloth.

6. The 3D printed skull cap with enhanced protection according to claim 5, characterized in that: The edge of the bottom of the protective cap body is provided with a mounting groove which is arranged at a position opposite to the soft cushion model and extends along the circumference of the soft cushion model, and the soft cushion model is clamped in the mounting groove.

7. The 3D printed skull cap with enhanced protection according to any one of claims 1 to 6, characterized in that: The method for manufacturing the protective cap body and the cushion model (3) comprises the following steps: S1. Obtain the patient's three-dimensional skull model before and after surgery (1); S2, smoothing the surface defects of the three-dimensional skull models (1) before and after surgery; generating corresponding NURBS surface models; S3. Using the skull defect range on the postoperative three-dimensional skull model (1) as a reference, cut a block from the preoperative three-dimensional skull model (1) as a protective cap model (2). The range of the protective cap model (2) is based on the range that can cover the postoperative skull defect range, and adjust the thickness of the protective cap model (2); S4, aligning the cut protective cap model (2) onto the postoperative three-dimensional skull model (1), and leaving an annular gap between the bottom of the edge of the protective cap model (2) and the soft tissue of the human head for installing the cushion model (3); S5. Generate a soft cushion model (3) according to the shape of the annular gap. The soft cushion model (3), the protective cap model (2) and the postoperative skull three-dimensional model (1) together form a skull cap three-dimensional model set; smooth the surface defects of the skull cap three-dimensional model set to generate a corresponding NURBS surface model; S6, importing the smoothed skull cap three-dimensional model set into the Ansys software in X_T format, and performing finite element stress analysis on the skull cap three-dimensional model set; and adjusting the soft cushion model (3) according to the result of the finite element stress analysis, and determining the optimization method of the soft cushion model (3) in the skull cap three-dimensional model set; S7, importing the protection cap model (2) and the soft cushion model (3) of the optimized and adjusted skull cap three-dimensional model set into a 3D printing device, and forming them by 3D printing.

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