CN113768668B

CN113768668B - Modeling method for designing personalized medical mandible model based on TPMS

Info

Publication number: CN113768668B
Application number: CN202111051374.2A
Authority: CN
Inventors: 王心彧; 宿玉成; 郑晓晓; 宋颐函; 孙子惠; 秦欣玉
Original assignee: Jiamusi University
Current assignee: Jiamusi University
Priority date: 2021-09-08
Filing date: 2021-09-08
Publication date: 2023-04-14
Anticipated expiration: 2041-09-08
Also published as: CN113768668A

Abstract

The invention discloses a modeling method for designing an individualized medical mandible model based on TPMS, which comprises the following steps: extracting data; reverse modeling; and (4) performing Boolean operation. Separating the mandible to be repaired by a threshold value according to the real image data of the mandible to be repaired of the patient, and carrying out reverse modeling after gridding treatment to obtain a corresponding solid model; boolean operation is carried out on a typical Gyroid structure in TPMS to obtain a bionic bone scaffold with the Gyroid structure, and the condyloid process of the bionic bone scaffold is solidified, so that the removal of subsequent 3D printing support is facilitated, the strength of the lower edge of the mandible to be repaired is enhanced, and a preset-thickness sheet tightly attached to the lower edge of the porous mandible is designed. The modeling method takes the TPMS structure as a unit cell, and performs porous design on the mandible to be repaired, so that the excellent mechanical property and biological property of the TPMS structure are organically combined with the bone scaffold, and the TPMS structure can become clinically effective bone scaffold design.

Description

Modeling method for designing personalized medical mandible model based on TPMS

Technical Field

The invention relates to the technical field of medical prosthesis, in particular to the technical field of implantable prosthesis, and particularly relates to a modeling method for designing an individualized medical mandible model based on TPMS.

Background

The repair and reconstruction of the defective medical prosthesis has been a research hotspot in the field of medical surgery, such as artificial total hip joints, artificial skull, mandible and the like; the following jaw bone restoration and reconstruction is an example of research hot spot of oral and maxillofacial surgery, and not only the form and facial contour of the medical prosthesis, but also the physiological function of the medical prosthesis is required to be restored. Currently, bone grafting is mainly relied on in the repair and reconstruction of the medical prosthesis defect, the application history of autologous bone grafting is long, the autologous bone grafting is still generally adopted clinically so far, and the autologous bone grafting is considered to be the best method for repairing the small-section bone defect at present; secondly, autologous massive bone grafts which are not vascularized in the oral cavity are also common, and in addition, autologous bone grafts with vascular pedicles can also repair the defects of the medical prosthesis, but the surgical damage is larger.

Therefore, the search for bionic substitutes of natural bones for bone transplantation is currently generally considered to be a more ideal treatment method.

In recent years, researchers find that some porous metals such as porous titanium, porous nickel titanium and the like are ideal substitutes for human bones, the porous structure can effectively promote bone ingrowth and osseointegration, and with the development of additive manufacturing technology, some designs related to porous medical prosthesis are developed.

In the related art, a three-cycle minimized Surface (TPMS) is a Surface that exhibits periodicity in three independent directions in a three-dimensional space, and has a characteristic that an average curvature is zero (also referred to as a minimized Periodic Surface). The TPMS can be infinitely expanded in three periodic directions, provides a model for accurately describing various physical structures in the natural and artificial world, and particularly can realize digital representation of porous structures. The minimized curved surface geometric shape structure is commonly existed in the nature, such as beetle, butterfly wing, animal skeleton, etc.

Therefore, how to apply the related technology TPMS to design a medical prosthesis becomes a new breakthrough, and how to overcome or optimize the above-mentioned problem of repair and reconstruction after the defect of the medical prosthesis in the prior art, practitioners of the same industry are in urgent need to solve.

Disclosure of Invention

The invention aims to provide a modeling method for designing an individual medical mandible model based on TPMS (tire pressure monitor System). The TPMS structure is used as a unit cell to carry out porous design on a medical prosthesis, so that the excellent mechanical property and biological property of the TPMS structure are organically combined with a bone scaffold, the TPMS is expected to be used as a clinically effective bone scaffold design, and a selection method is provided for the clinical modeling design of the scaffold; can avoid the problem of great surgical damage of the traditional medical prosthesis for repairing defects.

In order to achieve the purpose, the invention adopts the technical scheme that:

the embodiment of the invention provides a modeling method for designing an individualized medical mandible model based on TPMS, which comprises the following steps:

s10, acquiring image data of a mandible to be repaired corresponding to a patient, and preliminarily extracting a model of the mandible area to be repaired;

s20, performing reverse modeling according to the model of the mandible area to be repaired to obtain a corresponding entity model;

s30, selecting proper unit cell size, porosity and grid precision of the entity model to obtain a bionic bone scaffold with a Gyroid structure;

s40, setting different coordinate systems for the two entity models respectively, and performing Boolean operation intersection to obtain a mandible slice to be repaired with a preset thickness;

s50, designing a solid condyloid process structure and the remaining to-be-repaired mandible part of the Gyroid structure, and combining to obtain a bionic scaffold of the individualized Gyroid structure and the to-be-repaired mandible;

and S60, fitting the mandible slice to be repaired and the bionic support of the mandible to be repaired to obtain the personalized medical mandible model corresponding to the patient.

Further, the step S20 includes:

and carrying out reverse modeling on the model of the mandible area to be repaired through operations of smoothing and denoising, editing contour lines, constructing a surface patch and fitting the surface patch to obtain the STL-format solid model.

Further, the step S30 includes:

and (3) introducing the solid model into lattice designed based on Matlab, selecting proper unit cell size, porosity and grid precision, fitting the selected unit cell size, porosity and grid precision with the solid model in the step (S20), and deriving the porous bionic bone scaffold with the Gyroid structure.

Further, the step S40 includes:

setting a space coordinate system (0,0,0) of the solid model in the step S20 as a first model;

setting a space coordinate system (0, z) of the solid model in the step S20 as a second model;

performing Boolean operation intersection on the first model and the second model to obtain mandible fragments to be repaired;

and smoothing the mandible residual to be repaired to obtain the mandible residual with the thickness of z.

Further, the step S50 includes:

setting a cube, comparing sizes of the condyloid processes, extending to a sigmoid notch, performing Boolean operation on the cube and the solid model in the step S20, and deriving a solid condyloid process structure;

setting a cube again, comparing the sizes of condyloid processes, extending to a sigmoid notch, performing Boolean operation on the cube and the bionic bone scaffold with the Gyroid structure in the step S30, and deriving the remaining mandible part to be repaired of the Gyroid structure;

and combining the solid condyloid-process structure with the remaining mandible part to be repaired of the Gyroid structure to obtain the bionic scaffold of the mandible to be repaired, which has the personalized Gyroid structure.

Further, the step S60 includes:

and combining or performing Boolean operation intersection on the mandible slices to be repaired in the step S40 and the bionic scaffold of the mandible to be repaired in the step S50 to obtain an STL format file of the personalized medical mandible model corresponding to the patient.

Compared with the prior art, the invention has the following beneficial effects:

a modeling method for designing an individualized medical mandible model based on TPMS comprises the following steps: extracting data; reverse modeling; and performing Boolean operation. Separating the mandible to be repaired by a threshold value according to the real image data of the mandible to be repaired of the patient, and carrying out reverse modeling after gridding treatment to obtain a corresponding solid model; boolean operation is carried out on a typical Gyroid structure in TPMS to obtain a bionic bone scaffold with the Gyroid structure, and the condyloid process of the bionic bone scaffold is solidified, so that the removal of subsequent 3D printing support is facilitated, the strength of the lower edge of the mandible to be repaired is enhanced, and a preset-thickness sheet tightly attached to the lower edge of the porous mandible is designed. The modeling method takes the TPMS structure as a unit cell, and performs porous design on the mandible to be repaired, so that the excellent mechanical property and biological property of the TPMS structure are organically combined with the bone scaffold, the TPMS structure is expected to be used as a clinically effective bone scaffold design, and a selection method is provided for the clinical modeling design of the scaffold. In addition, the modeling method is not only suitable for total mandible replacement surgery, but also suitable for the design of segmental mandible resection stents after tumor cyst, trauma and other surgeries, and can also be used for TPMS design of bones of the whole body.

Drawings

Fig. 1 is a flowchart of a modeling method for designing a personalized medical mandible model based on TPMS according to an embodiment of the present invention.

Fig. 2 is a flowchart of a mandible model modeling method according to an embodiment of the present invention.

Fig. 3 is an effect diagram of a mandible model according to an embodiment of the present invention.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further explained by combining the specific embodiments.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "both ends", "one end", "the other end", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "connected," and the like are to be construed broadly, such as "connected," which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the related art, the TPMS describes the stent structure through a mathematical function, and the pore parameters can be adjusted by changing the parameters thereof, thereby realizing the change of the structure and mechanical properties of the stent. The continuous curved surface structure generated by the TPMS method has good topological optimization, and can provide better self-supporting property in the forming process of the selective laser melting process. The surface area to volume ratio is very high, and the TPMS stent with high specific surface area is helpful to enhance the adhesion, migration and proliferation of cells. Many cellular and biological functions such as ion exchange, oxygen diffusion and nutrient transport occur on their surfaces, and therefore, TPMS scaffolds can provide better biological signals for cells cultured thereon. Compared to a regular lattice structure support, an infinitely continuous surface with smooth joints ensures less stress concentration and higher mechanical properties. The TPMS function can more easily realize the change of the structural parameters, overcome the defects in the structural design of the traditional truss unit cell, and automatically obtain the porous bone scaffold digital model with a complex microstructure and a high-quality surface.

Referring to fig. 1, an embodiment of the present invention provides a modeling method for designing a personalized medical mandible model based on TPMS, including:

s10, acquiring image data of a mandible to be restored corresponding to a patient, and preliminarily extracting a model of the mandible area to be restored;

s40, respectively setting different coordinate systems for the two entity models, and performing Boolean operation intersection to obtain a mandible sheet to be repaired with a preset thickness;

s50, designing the remaining mandible parts to be repaired of the solid condyloid apophysis structure and the Gyroid structure, and combining to obtain a bionic scaffold of the mandible to be repaired, which is of an individualized Gyroid structure;

and S60, fitting the mandible slices to be repaired and the bionic scaffold of the mandible to be repaired to obtain the personalized medical mandible model corresponding to the patient.

In step S10, for example, CBCT data image data of the jaw bone of the patient is obtained, and the image data may be introduced into the miccis 19.0 software, for example, to perform a preliminary model extraction. The Mimics19.0 software is used as a medical image segmentation processing tool, and can help a user to simulate a three-dimensional medical image and rapidly segment the three-dimensional medical image, so that the high-precision three-mode simulation and the like of the image of a patient are performed, and the simulation function of the image such as MRI, three-dimensional ultrasound, MRI and the like is built in the software.

In the step S20, for example, the model preliminarily extracted in the step S10 is imported into the Geomagic Wrap2017 software, and is subjected to smooth denoising, contour line editing, surface patch constructing and surface patch fitting operations to perform reverse modeling, so as to obtain the entity model in the STL format.

The Geomagic Wrap is a 3D model data conversion application tool brought by Geomagic corporation, comprises point cloud and polygon editing functions and a powerful face making tool, and can automatically generate an accurate digital model by scanning point cloud according to any real part. Scanning data and 3D files were easily converted into perfect reverse engineering 3D models using Geomagic Wrap.

In step S30, a Gyroid structure is processed; and (5) importing the entity model in the STL format in the step (S20) into latticilt designed based on Matlab, selecting a proper unit cell structure, unit cell size, porosity and grid precision, fitting the unit cell structure, the unit cell size, the porosity and the grid precision, and deriving the porous medical prosthesis stent with the Gyroid structure.

In the step S40, designing a sheet; for example, 2 solid models in step S20 are introduced into Magics 23.0 software, and boolean operations are performed on intersection after a coordinate system is determined, so as to obtain a mandible slice to be repaired with a certain thickness (for example, 0.5 mm);

specifically, in STL file editing software such as Magics 23.0 software, the solid model of step S20 is imported, and a spatial coordinate system (0,0,0) is determined; and (5) importing the solid model in the step (S20) again, determining a space coordinate system (0,0,0.5), performing Boolean operation intersection on the two to obtain the mandible fragment to be repaired, manually dividing an unnecessary range such as a lifting part to delete the unnecessary range, keeping the sheet at the lower edge of the mandible to be repaired as far as possible, and performing smoothing treatment on the sheet to obtain the mandible sheet to be repaired with the thickness of 0.5 mm.

In step S50, in order to avoid soft tissue ingrowth during the healing process after opening the joint inferior cavity during a medical prosthesis replacement procedure (such as a mandibular replacement surgery or a joint replacement procedure), the condyloid process is solidified; for example, in Magics 23.0 software, a cube is set, the size of the condyloid process is compared, the condyle is extended to a sigmoid notch, and Boolean operation is performed on the condyle and the entity model in the step S20 to derive a solid condyloid process structure; according to the same principle, boolean operation is carried out on the cube and the bracket with the Gyroid structure in the step S30, and the remaining mandible part to be repaired of the Gyroid structure is led out; and carrying out 'merging parts' or 'Boolean operation intersection' on the two to obtain the mandible with the personalized Gyroid structure to be repaired.

In step S60, fitting data, unifying the mandible slices to be repaired in step S40 and the bionic scaffold to be repaired of the mandible in step S50, performing "merging parts" or "boolean operation intersection" to obtain the personalized medical prosthesis model of the mandible to be repaired corresponding to the patient, and deriving a final STL format file.

The modeling method of the personalized medical prosthesis model designed based on the TPMS, provided by the embodiment of the invention, firstly designs the medical prosthesis model based on the TPMS, and compared with the traditional modeling mode, the medical prosthesis model has the following advantages: (1) the TPMS function can more simply realize the change of the structural parameters, overcome the defects in the structural design of the traditional truss unit cell, and automatically obtain the porous bone scaffold digital model with a complex microstructure and a high-quality surface. (2) Compared to a regular lattice structure support, an infinite continuous surface with a smooth joint ensures less stress concentration and higher mechanical properties, and also has good topological optimization, providing self-support during printing. (3) The high specific surface area of the TPMS scaffold helps to enhance cell adhesion, migration and proliferation, providing better biological signals to cells cultured thereon. (4) The design of the porous structure reduces the elastic modulus and reduces stress shielding.

The following is a detailed description of the modeling of a patient's desired mandible medical prosthesis:

referring to fig. 2, a flowchart of a modeling method of a mandible model is shown, in the drawing, the NX-end osteotomy means that if not the entire mandible is replaced but only a part of the mandible needs to be replaced, an osteotomy design can be performed on an interested region in NX software. The method comprises the following specific steps:

1) And (3) importing CBCT data of one patient into Mimics19.0 software, performing threshold segmentation, and independently extracting data of the mandible to obtain a mandible triangle patch model.

2) And (3) introducing the mandible preliminarily extracted by the Mimics19.0 software into the Geomagic Wrap2017 software, and performing reverse modeling through operations of smoothing and denoising, contour line editing, surface sheet construction and surface sheet fitting to obtain the STL-format solid model. If not the entire mandible replacement, only a part of the mandible replacement is needed, then the interesting area can be derived after osteotomy design in NX software.

3) And (3) introducing the entity model into lattice designed based on Matlab by treating the Gyroid structure, selecting the Gyroid structure for filling, the unit cell size of 6mm, the porosity of 65% and the grid precision of 30%, fitting the Gyroid structure and the lattice, and deriving the porous mandible scaffold with the Gyroid structure.

4) In order to avoid the tilting deformation of a Gyroid mandible structure caused by the design without supports in the 3D printing process, the influence on the product quality caused by the support entering a porous structure, the convenient removal of subsequent supports and the enhancement of the strength of the lower edge of the mandible, the mandible sheet is designed. Importing the mandible solid model in the step 2) into Magics 23.0 software, and determining a space coordinate system (0,0,0); introducing the mandible solid model in the step 2) again, determining a space coordinate system (0,0,0.5), performing Boolean operation intersection on the two to obtain mandible fragments, manually dividing an unnecessary range such as a lifting part to delete the unnecessary range, keeping the slices at the lower edge of the mandible as much as possible, and performing smoothing treatment on the slices to obtain the mandible slices with the thickness of 0.5 mm;

5) To avoid soft tissue ingrowth during healing after opening the joint inferior cavity during the mandibular replacement surgery, the condyloid process was solidified. Setting a cube in Magics 23.0 software, comparing sizes of condyloid processes, extending to a sigmoid notch, performing Boolean operation on the cube and the solid mandible (solid model) in the step 2), and deriving a solid condyloid process structure; according to the same principle, boolean operation is carried out on the cube and the bracket with the Gyroid structure in the step 3), a unified coordinate system of the rest mandible parts with the Gyroid structure is derived, and the cube and the bracket with the Gyroid structure are subjected to 'merging part' or 'Boolean operation intersection' to obtain the mandible with the personalized Gyroid structure;

6) Fitting data, namely unifying a coordinate system of the mandible slices and the mandible with a Gyroid structure with a solidified condyle, performing 'merging parts' or 'Boolean operation intersection', and exporting a final STL format file; as shown with reference to fig. 3.

The invention is not only suitable for extracting the whole or part of the mandible, but also suitable for TPMS design of other metal prostheses of human bodies, and is also suitable for TPMS structures except Gyroid structures.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments illustrated above, which are merely illustrative of the principles of the present invention, and that various changes and modifications may be made without departing from the spirit and scope of the invention, such as by applying the method to a full-length skeletal poromeric design or by selecting a TPMS of a different construction, and such changes and modifications are intended to be within the scope of the claimed invention. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A modeling method for designing an individualized medical mandible model based on TPMS is characterized by comprising the following steps:

s60, fitting the mandible slices to be repaired and the bionic scaffold of the mandible to be repaired to obtain an individualized medical mandible model corresponding to the patient;

the step S40 includes:

setting a space coordinate system (0,0,0) as a first model for the solid model in the step S20;

smoothing the mandible residual to be repaired to obtain the mandible residual with the thickness of z;

the step S50 includes:

setting a cube, comparing the size of the condyloid process, extending to a sigmoid notch, performing Boolean operation on the cube and the entity model in the step S20, and deriving a solid condyloid process structure;

2. The modeling method for designing the personalized medical mandible model based on the TPMS as claimed in claim 1, wherein the S20 step comprises:

and carrying out reverse modeling on the model of the mandible area to be repaired through operations of smoothing and denoising, contour line editing, surface sheet construction and surface sheet fitting to obtain the entity model in the STL format.

3. The modeling method for designing a personalized medical mandible model based on TPMS as claimed in claim 1, wherein the S30 step comprises:

and (4) introducing the solid model into lattice designed based on Matlab, selecting proper unit cell size, porosity and grid precision, fitting the selected solid model with the solid model obtained in the step (S20), and deriving the porous bionic bone scaffold with the Gyroid structure.

4. The modeling method for designing the personalized medical mandible model based on the TPMS as claimed in claim 1, wherein the S60 step comprises: