CN113408174A - Skeleton model construction method and device, computer equipment and storage medium - Google Patents

Skeleton model construction method and device, computer equipment and storage medium Download PDF

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CN113408174A
CN113408174A CN202110720511.0A CN202110720511A CN113408174A CN 113408174 A CN113408174 A CN 113408174A CN 202110720511 A CN202110720511 A CN 202110720511A CN 113408174 A CN113408174 A CN 113408174A
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bone
geometric
physical parameters
boundary
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张维声
郭旭
王作伟
梅跃
张一可
蒋浚
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Dalian University of Technology
Xuanwu Hospital
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Dalian University of Technology
Xuanwu Hospital
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
    • G—PHYSICS
    • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
    • G16H—HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
    • G16H50/00—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics
    • G16H50/20—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics for computer-aided diagnosis, e.g. based on medical expert systems
    • G—PHYSICS
    • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
    • G16H—HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
    • G16H50/00—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics
    • G16H50/50—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics for simulation or modelling of medical disorders
    • G—PHYSICS
    • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
    • G16H—HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
    • G16H70/00—ICT specially adapted for the handling or processing of medical references
    • G16H70/60—ICT specially adapted for the handling or processing of medical references relating to pathologies
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2111/00—Details relating to CAD techniques
    • G06F2111/04—Constraint-based CAD
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces

Abstract

The embodiment of the invention discloses a bone model construction method, which comprises the following steps: obtaining a geometric model according to the scanning data of the skeleton of the patient, and setting physical parameters to obtain an original model; applying boundary conditions and loads to the original model, and carrying out simulation analysis to obtain boundary displacement data; setting different material parts in the geometric model as at least one isotropic material, and performing inversion calculation according to preset boundary conditions, loads and boundary displacement data to obtain physical parameters of the isotropic material; and giving the physical parameters of the isotropic material to the geometric model to obtain the bone model. According to the invention, by carrying out inversion calculation and reversely deducing physical parameters of the simplified model capable of representing the physiological and mechanical characteristics of the original model, the simplified bone model is further obtained, so that simulation analysis is carried out, and an accurate analysis result can be obtained under the condition of reducing the calculation amount of the simulation analysis. Further, a bone model construction apparatus, a computer device, and a storage medium are disclosed.

Description

Skeleton model construction method and device, computer equipment and storage medium
Technical Field
The invention relates to the technical field of skeleton model simulation, in particular to a skeleton model construction method, a skeleton model construction device, computer equipment and a storage medium.
Background
Clinically, spinal fusion is the main method for treating spinal diseases, and intervertebral fusion devices are widely applied to spinal fusion of cervical vertebrae and lumbar vertebrae. In the spinal fusion operation, the fusion cage has the advantages of realizing immediate postoperative stability, expanding and maintaining the intervertebral space height, promoting bone grafting fusion and the like, thereby being rapidly developed in clinical use. Meanwhile, the fusion failure phenomena of subsidence, displacement, no fusion and the like of the postoperative intervertebral fusion device caused by the mismatching of the standard specification of the intervertebral fusion device and the pathological environment of a patient also arouse more and more attention of people. Therefore, how to design the fusion cage in a targeted manner for the special pathological environment of each patient and realize the personalized customized service of the fusion cage has reference value on the academic research on the research of the biomechanics of the human spine and has important significance on promoting the development and progress of the intervertebral fusion.
The personalized customized fusion cage firstly needs a three-dimensional model of the diseased bone of a patient, designs and generates a fusion cage model according to the diseased bone model, and finally produces the fusion cage through means such as 3D printing. The bone model constructed by adopting the finite element method has the advantages of low cost, high repeatability, convenience for parametric research and the like, and is widely applied to the research of the biomechanics of the orthopedics department. When the individual medical treatment scheme is subjected to biomechanical evaluation based on finite element simulation, a required treatment area and related human bones near the required treatment area need to be modeled to research feasibility, effectiveness and the like of related treatment means. Because the real human skeleton is non-uniform material, the material properties of the end plate, nucleus pulposus, annulus fibrosus and other tissues are different, if the real parameters of the materials are completely adopted in the process of designing the fusion cage, although a relatively accurate simulation result can be obtained, the calculated amount can be greatly improved. Therefore, how to construct a model not only can make the simulation result accurate, but also can reduce the calculation amount of the simulation process, which is a problem to be solved urgently at present.
Disclosure of Invention
In view of the above, it is necessary to provide a bone model construction method, apparatus, computer device and storage medium, which can easily and efficiently obtain accurate simulation results from a constructed bone model.
A method of bone model construction, the method comprising:
performing geometric modeling according to the scanning data of the skeleton of the patient to obtain a geometric model, and setting corresponding physical parameters for different material parts in the geometric model to obtain an original model;
applying preset boundary conditions and loads representing the physiological mechanics of the patient skeleton to the original model, and performing simulation analysis to obtain boundary displacement data of the original model;
receiving the setting operation of an operator, setting the different material parts in the geometric model as at least one isotropic material according to the setting operation, and performing inversion calculation according to the preset boundary condition, the load and the boundary displacement data to obtain physical parameters of the isotropic material;
and assigning physical parameters of the isotropic material to the geometric model to obtain a skeleton model capable of representing the physiological and mechanical characteristics of the original model.
A bone model construction apparatus, the apparatus comprising:
the modeling module is used for carrying out geometric modeling according to the scanning data of the skeleton of the patient to obtain a geometric model, and setting corresponding physical parameters for different material parts in the geometric model to obtain an original model;
the problem correcting module is used for applying preset boundary conditions and loads representing the physiological mechanics of the skeleton of the patient to the original model, and performing simulation analysis to obtain boundary displacement data of the original model;
the inverse problem module is used for receiving the setting operation of an operator, setting the different material parts in the geometric model as at least one isotropic material according to the setting operation, and performing inversion calculation according to the preset boundary condition, the load and the boundary displacement data to obtain the physical parameters of the isotropic material;
and the assignment module is used for assigning the physical parameters of the isotropic material to the geometric model to obtain a bone model capable of representing the physiological and mechanical characteristics of the original model.
A computer device comprising a memory and a processor, the memory storing a computer program that, when executed by the processor, causes the processor to perform the steps of:
Performing geometric modeling according to the scanning data of the skeleton of the patient to obtain a geometric model, and setting corresponding physical parameters for different material parts in the geometric model to obtain an original model;
applying preset boundary conditions and loads representing the physiological mechanics of the patient skeleton to the original model, and performing simulation analysis to obtain boundary displacement data of the original model;
receiving the setting operation of an operator, setting the different material parts in the geometric model as at least one isotropic material according to the setting operation, and performing inversion calculation according to the preset boundary condition, the load and the boundary displacement data to obtain physical parameters of the isotropic material;
and assigning physical parameters of the isotropic material to the geometric model to obtain a skeleton model capable of representing the physiological and mechanical characteristics of the original model.
A computer-readable storage medium storing a computer program which, when executed by a processor, causes the processor to perform the steps of:
performing geometric modeling according to the scanning data of the skeleton of the patient to obtain a geometric model, and setting corresponding physical parameters for different material parts in the geometric model to obtain an original model;
Applying preset boundary conditions and loads representing the physiological mechanics of the patient skeleton to the original model, and performing simulation analysis to obtain boundary displacement data of the original model;
receiving the setting operation of an operator, setting the different material parts in the geometric model as at least one isotropic material according to the setting operation, and performing inversion calculation according to the preset boundary condition, the load and the boundary displacement data to obtain physical parameters of the isotropic material;
and assigning physical parameters of the isotropic material to the geometric model to obtain a skeleton model capable of representing the physiological and mechanical characteristics of the original model.
According to the bone model construction method, the device, the computer equipment and the storage medium, geometric modeling is performed according to the scanning data of the patient bone to obtain a geometric model, and corresponding physical parameters are set for different material parts in the geometric model to obtain an original model; applying preset boundary conditions and loads representing the physiological mechanics of the patient skeleton to the original model, and performing simulation analysis to obtain boundary displacement data of the original model; receiving the setting operation of an operator, setting the different material parts in the geometric model as at least one isotropic material according to the setting operation, and performing inversion calculation according to the preset boundary condition, the load and the boundary displacement data to obtain physical parameters of the isotropic material; and assigning physical parameters of the isotropic material to the geometric model to obtain a skeleton model capable of representing the physiological and mechanical characteristics of the original model. According to the invention, inversion calculation is carried out by a finite element updating method based on boundary displacement, and the shear modulus of the simplified bone model equivalent to the original model is reversely deduced according to the simulation analysis result of the positive problem of the original model, so that the simplified original model, namely the bone model, is obtained. The skeleton model can represent the mechanical property of the original model, and the simplified skeleton model is adopted for simulation analysis, so that an accurate analysis result can be obtained under the condition of reducing the calculation amount of the simulation analysis.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Wherein:
FIG. 1 is a flow diagram illustrating an implementation of a method for building a skeletal model according to an embodiment;
FIG. 2 is a graph comparing the cone rotation angle data of the simulation analysis results under various working conditions with the existing medical experimental data of the same type in one embodiment;
FIG. 3 is a flow chart illustrating an exemplary method for optimizing the design of a bone treatment device according to an embodiment;
FIG. 4 is a diagram illustrating an iterative optimization process for a method of moving deformable elements in one embodiment;
FIG. 5 is a flow diagram of solving an optimization problem using a mobile deformable element method in one embodiment;
FIG. 6 is an illustration of an optimal topology of an intervertebral cage according to one embodiment;
FIG. 7 is a flow chart illustrating an exemplary method of manufacturing the cage;
FIG. 8 is a block diagram showing the structure of a bone model building apparatus according to an embodiment;
FIG. 9 is a block diagram of an optimization system for a skeletal medical device in one embodiment;
FIG. 10 is a block diagram of an embodiment interbody cage manufacturing system;
FIG. 11 is a block diagram of a computer device in one embodiment.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, in one embodiment, a bone model construction method is provided, which specifically includes the following steps:
102, performing geometric modeling according to the scanning data of the skeleton of the patient to obtain a geometric model, and setting corresponding physical parameters for different material parts in the geometric model to obtain an original model.
Wherein, the bone of the patient refers to the bone part of the patient needing treatment, such as cervical vertebra, lumbar vertebra, femur, etc.; scanning around the bone part of the patient needing to be treated to obtain a large amount of scanning data, importing the scanning data into modeling software, then adopting a reverse engineering technology to perform operations such as filtering, interpolation, entity generation and the like on the two-dimensional section image obtained by scanning to establish a three-dimensional entity model, namely a geometric model, and then setting physical parameters of parts made of different materials in the geometric model to obtain an original model of the bone part of the patient needing to be treated.
In the illustrated embodiment of the present invention, the scan data is CT data, and the multi-scan CT data is used to construct a three-dimensional geometric model.
The geometric model is a model with a geometric shape and a connection relation, and has no material property and cannot be used for simulation calculation; the physical parameters refer to parameters of material properties, which are used for simulating real materials.
The original model is a finite element model with meshes divided, corresponding material attributes are set for units of different skeleton parts, accurate analysis data can be obtained when simulation analysis is carried out according to the original model, and in a general method, the original model is the basis for simulation analysis or other operations.
The human skeleton and the related parts thereof are various, and even the parts have a plurality of parts made of different materials, such as nucleus pulposus part and fiber ring part in intervertebral disc, so it can be understood that the calculation amount is very large when the medical problem is solved based on the original model, and especially when the model is fine or the calculation is complex, the calculation amount is greatly increased. The method simplifies different materials in the original model into one, two or more than two isotropic materials, and greatly simplifies the calculated amount because the isotropic material model is simple and has less physical parameters for representing the material properties and can be represented by only three parameters of elastic modulus, Poisson's ratio and shear modulus. The material properties of tissues such as ligaments and the like are not easy to measure, and compared with an original model in which tissues such as ligaments and the like generate mechanical response to the overall model, the simplified bone model can represent physiological mechanical characteristics and delete the tissues.
In one embodiment, the physical parameters of the isotropic material include two of shear modulus, elastic modulus, and poisson's ratio. Wherein the other physical parameter can be solved according to two physical parameters of shear modulus, elastic modulus and Poisson ratio.
And 104, applying preset boundary conditions and loads representing the physiological mechanics of the patient skeleton to the original model, and performing simulation analysis to obtain boundary displacement data of the original model.
The simulation analysis is carried out on the original model under the preset boundary condition and the load, the stress condition of the patient skeleton under the motion working condition corresponding to the preset load can be simulated, and the boundary displacement data of the original model under the preset boundary condition and the load is solved.
The boundary displacement data refers to the displacement of the model surface under the boundary condition and the load in the simulation analysis.
In order to solve the bone model capable of representing the physiological and mechanical characteristics of the original model, a positive problem of the original model needs to be solved, wherein the positive problem is to calculate boundary displacement data of the original model under a preset condition, then endow the boundary displacement data solved by the positive problem to a geometric model, set different material parts in the geometric model as at least one isotropic material, perform simulation analysis on the geometric model endowed with the boundary displacement data, the isotropic material, the preset boundary condition and the load by adopting the preset boundary condition and the load which are the same as those in the positive problem solving, and calculate physical parameters, including elastic modulus, shear modulus and poisson ratio, of the isotropic material of the bone model capable of representing the physiological and mechanical characteristics of the original model.
And 106, receiving a setting operation of an operator, setting the different material parts in the geometric model as at least one isotropic material according to the setting operation, and performing inversion calculation according to the preset boundary condition, the load and the boundary displacement data to obtain physical parameters of the isotropic material.
Here, the isotropic material refers to a material whose physical and chemical properties are not changed depending on the direction. The smaller the number of isotropic materials, the smaller the amount of calculation.
The physical parameters obtained by the inversion calculation refer to the physical parameters of the isotropic material of the bone model with the same mechanical performance characteristics under the same preset boundary conditions and loads. The same mechanical performance characteristics comprise the same boundary displacement as the original model and the same or similar original model surface and internal stress magnitude and distribution.
In one embodiment, the setting the different material portions in the geometric model to at least one isotropic material according to the setting operation further comprises: and simultaneously setting the poisson's ratio of each isotropic material.
It can be understood that when different material parts of different structures in the geometric model are simplified into an isotropic material, the obtained bone model capable of representing the physiological and mechanical characteristics of the original model is used as a calculation model of simulation, and the calculation amount is minimum. Of course, different material parts with different structures in the geometric model can be divided into a plurality of groups, each group is set to be an isotropic material, and the calculated amount is still greatly reduced compared with that when the original model is adopted for simulation.
Wherein when a portion in the model is set to a specific isotropic material, the poisson's ratio of the portion is also set at the same time.
In a general method, inverse problem calculation, that is, inversion calculation, of mechanical material distribution not only needs to measure boundary displacement, but also needs to measure internal displacement, but internal displacement is difficult to measure, or measurement accuracy is not enough, which easily causes a large error. The method is based on boundary displacement, and solves by adopting an optimization problem with constraint, so that the physical parameters of the isotropic material of the skeleton model which can represent the physiological and mechanical characteristics of the original model can be calculated.
The finite element updating method based on boundary displacement firstly converts an inverse problem into an optimization problem with constraints for solving, and the optimization formula is as follows:
Figure BDA0003136334700000051
and giving n groups of measurement boundary displacement data fields, minimizing the objective function pi, and solving to obtain the distribution of the shear modulus.
Wherein the first part of the objective function is a displacement dependent term: n is the number of data sets for which the boundary is shifted, N is the total number of cells on the boundary,
Figure BDA0003136334700000052
for the coefficients that are a component of the shape function,
Figure BDA0003136334700000053
the displacement is calculated for the ith set of finite elements,
Figure BDA0003136334700000054
the measured displacement for the ith group.
The second part of the objective function is a regularized correlation term, alpha is a regularization constant, and the size of the regularization term is controlled; n is a radical of nFor the total number of cells in the problem domain,
Figure BDA0003136334700000055
as a function of the node shear modulus,
Figure BDA0003136334700000056
simulating the shear modulus, displacement and hydrostatic pressure of the node as a difference function for a shape function; c is a constant, and the term can ensure that the target function does not have singularity in the derivation process.
And adopting corresponding optimization algorithms aiming at different objective functions to optimize the objective functions, continuously updating physical parameters in the fitting process, and stopping calculation and outputting the physical parameters obtained by inversion calculation when the objective functions are smaller than a given threshold value.
In one embodiment, during inversion calculation, the attribute of a model material is assumed to be an incompressible elastic material and is in a two-dimensional plane strain state, and an optimization algorithm is adopted to find a structural part shear modulus which enables a target function to be minimum according to known model displacement data; the objective function formula is as follows:
Figure BDA0003136334700000061
wherein F is an objective function, n is the number of data sets of boundary displacement,
Figure BDA0003136334700000062
is the total number of cells on the boundary,
Figure BDA0003136334700000063
is a unit node on the boundary and NnIs the total number of units of the structure.
Figure BDA0003136334700000064
And
Figure BDA0003136334700000065
the displacements are calculated and measured for the nodes on the ith set of boundaries respectively,
Figure BDA0003136334700000066
is the weight due to finite element interpolation;
Figure BDA0003136334700000067
omega represents the spatial region of the entire structure as a function of node shear modulus. c is a very small constant to ensure that the regularization term is differentiable, and α is the regularization constant to control the magnitude of the regularization term.
And 108, assigning physical parameters of the isotropic material to the geometric model to obtain a skeleton model capable of representing the physiological and mechanical characteristics of the original model.
The skeleton model is a uniform material model capable of representing the physiological and mechanical characteristics of an original model of a non-uniform material, and physical parameters obtained through inversion calculation are given to an isotropic material part in a geometric model, so that the skeleton model which is more simplified compared with the original model and capable of representing the physiological and mechanical characteristics of the original model is obtained.
The skeleton model construction method comprises the steps of carrying out geometric modeling according to scanning data of a patient skeleton to obtain a geometric model, and setting corresponding physical parameters for different material parts in the geometric model to obtain an original model; applying preset boundary conditions and loads representing the physiological mechanics of the patient skeleton to the original model, and performing simulation analysis to obtain boundary displacement data of the original model; receiving the setting operation of an operator, setting the different material parts in the geometric model as at least one isotropic material according to the setting operation, and performing inversion calculation according to the preset boundary condition, the load and the boundary displacement data to obtain physical parameters of the isotropic material; and assigning physical parameters of the isotropic material to the geometric model to obtain a skeleton model capable of representing the physiological and mechanical characteristics of the original model. According to the invention, inversion calculation is carried out by a finite element updating method based on boundary displacement, and the shear modulus of the simplified bone model equivalent to the original model is reversely deduced according to the simulation analysis result of the positive problem of the original model, so that the simplified original model, namely the bone model, is obtained. The skeleton model can represent the mechanical property of the original model, and the simplified skeleton model is adopted for simulation analysis, so that an accurate analysis result can be obtained under the condition of reducing the calculation amount of the simulation analysis.
In one embodiment, performing geometric modeling according to CT data of a patient's bone to obtain a geometric model, and setting corresponding physical parameters for different material portions in the geometric model to obtain an original model, includes: generating a geometric model from the CT data; and carrying out trimming and coupling operations on the geometric model, and setting corresponding physical parameters for each part made of different materials to obtain the original model.
The three-dimensional geometric model is generated according to two-dimensional CT data, the accuracy of the CT data needs to be ensured, and therefore the CT data needs to be preprocessed according to the modeling rules of modeling software to ensure that the generated geometric model can correspond to the real physiological and pathological conditions of the skeleton of a patient and not only to the scanning data.
After obtaining the geometric model, soft tissue parts or other parts which have strong interaction with bones need to be added, and existing parts are further divided, such as cortical bone and cancellous bone of a vertebral body part, nucleus pulposus and annulus fibrosus of a vertebral disc part and the like; therefore, the geometric model needs to be further modified, the geometric model and the added component model are coupled, and corresponding physical parameters are set for each different material part, so as to finally obtain an original model capable of accurately simulating the bone physiological and pathological conditions of the patient. The components that may need to be added are, for example, intervertebral discs, ligaments, cartilage endplates, posterior structures of vertebral bodies, articular process cartilage, joint capsules, etc., and the operator can determine whether the addition is needed according to the bone part to be treated and the corresponding treatment plan.
In one embodiment, the generating a geometric model from the CT data comprises: segmenting bone data from the CT data according to a preset gray value threshold; receiving an extraction range determined by an operator, and extracting target bone data from the bone data according to the extraction range; receiving filling processing operation of the operator on the target bone data to eliminate gray value deviation caused by CT scanning; and generating the geometric model according to the target bone data after filling processing.
The gray values of different tissues of a human body, which are expressed in scanning data due to different densities, are different, the gray values corresponding to the tissues with higher tissue densities are higher, the general fluctuation range of the gray values of the tissues with the same structure is smaller, and other soft tissues in close contact with bone tissues can be distinguished and extracted according to the gray value difference principle. In one embodiment, the modeling software is a Mimics software, the threshold range of the segmentation is set according to the gray value of the bone tissue, and the selected gray value range 160-.
Wherein, it is easy to understand that when simulation analysis and operation are performed, only the critical bone region to be treated is taken as a calculation object, so as to save calculation resources; therefore, after the bone data in the CT data is extracted, a key part is further extracted from the bone data as the target bone data, so as to improve the calculation speed of the subsequent modeling and simulation analysis.
When the scan data capable of accurately representing the bone condition of the patient is converted into a geometric model, the scan data is deviated due to different modeling rules, and therefore the scan data needs to be processed first. During scanning, the gray values of the scanned data obtained due to different tissue densities are different, and the gray value deviation in the target bone data can cause a plurality of cavities to be generated inside the generated geometric model, so that the contour lines of bones need to be extracted from the target bone data, and the inside of the contour line of each scanned data image is filled, so that the gray values of the target bones in the scanned data are consistent, and the inside of the established geometric model can be complete and seamless.
In one embodiment, the geometric model is a lumbar vertebral geometric model; the trimming and coupling operations on the geometric model and setting corresponding physical parameters for each different material part to obtain the original model comprise: smoothing and segmenting the geometric model; deriving intervertebral disc data according to the processed geometric model, and generating an intervertebral disc model according to the intervertebral disc data; determining ligament attachment points according to the geometric model, and generating a ligament model according to the ligament attachment points; and coupling the geometric model, the intervertebral disc model and the ligament model, and setting corresponding physical parameters for each part made of different materials to obtain the original model.
The generated geometric model is rough, and the surface of the geometric model needs to be subjected to smoothing treatment so as to facilitate subsequent calculation; in addition, the different structural parts adhered to each other in the geometric model need to be segmented, for example, two adjacent vertebrae should be independent structural parts in the model, but when the two parts are regarded as the same part for modeling when the scan data is converted into the geometric model, the two adhered vertebrae need to be segmented.
In the lumbar vertebra skeleton environment, intervertebral discs, ligaments and lumbar vertebrae have strong interaction, so that an original model capable of accurately simulating the physiological and pathological conditions of bones of a patient is generated, and the intervertebral discs and the ligament components are necessary model components; the density of the intervertebral disc and the ligament is similar to that of soft tissues around the vertebral body, and the extraction cannot be directly distinguished through gray values in scanning data, so that the intervertebral disc model and the ligament model are deduced and generated according to a spinal structure represented by a geometric model and attachment positions of various ligaments, and finally, the intervertebral disc model and the ligament model are coupled with the geometric model, and an original model is generated after corresponding physical parameters are set for each part made of different materials.
The method comprises the following steps of (1) deducing relevant data of an intervertebral disc according to upper and lower curved surface characteristics of upper and lower vertebrae, and generating an intervertebral disc model according to the relevant data of the intervertebral disc; ligament attachment points are determined through anatomical laws, medical research literature and example data, and then ligament models are generated according to the ligament attachment points.
After the geometric model is gridded, the setting of an operator on the geometric model is received, physical parameters are given to each model part, each model part is assembled, and contact setting and boundary condition setting are carried out to obtain an original model for subsequent numerical simulation.
In one embodiment, the deriving disc data from the processed geometric model, and generating a disc model from the disc data comprises: deducing the upper and lower curved surfaces of the intervertebral disc according to the contact surface between the vertebral body bones and the intervertebral disc in the geometric model; receiving nucleus pulposus position curves drawn by the operator on the upper and lower curved surfaces, and separating nucleus pulposus regions and annulus fibrosus regions of the upper and lower curved surfaces according to the nucleus pulposus position curves; generating the disc model from the upper and lower curved surfaces of the disc, the nucleus pulposus region and the annulus fibrosus region.
And deducing the characteristics of the upper and lower curved surfaces of the intervertebral disc according to the contact surface between the vertebral body bones and the intervertebral disc in the geometric model, and generating the upper and lower curved surfaces of the intervertebral disc by utilizing modeling software according to the characteristics of the upper and lower curved surfaces.
The intervertebral disc consists of nucleus pulposus and annulus fibrosus, the nucleus pulposus part is about forty percent of the total volume, and an operator can draw a nucleus pulposus position curve of the intervertebral disc according to anatomical characteristics so as to separate the nucleus pulposus part and the annulus fibrosus part of the intervertebral disc, thereby obtaining the intervertebral disc model.
After the intervertebral disc model is obtained, carrying out grid division on the geometric model and the assembled integral model of the intervertebral disc model, carrying out quality inspection on the divided model grids after the grids are divided, and deleting or trimming the grids with unqualified quality.
In one embodiment, the determining a ligament attachment point from the geometric model, establishing a ligament model from the ligament attachment point, further comprises: determining ligament attachment points according to the anatomical structure of the spinal tissue in the geometric model, and establishing ligaments according to the ligament attachment points; and receiving ligament attributes corresponding to the ligaments set by the operator, and generating a ligament model according to the ligaments and the ligament attributes.
Determining ligament attachment points according to ligament anatomy and the anatomical structure of spinal tissues in the geometric model, establishing corresponding ligaments after determining ligament types according to the ligament attachment points, and giving ligament attribute values corresponding to the ligament types to the ligaments; and forming a ligament model by all the established ligaments, and coupling the ligament model with the geometric model according to the ligament attachment points.
In one embodiment, the geometric model is an atlantoaxial geometric model; the trimming and coupling operation on the geometric model to obtain the original model further comprises: smoothing and segmenting the geometric model; determining the attribute of a finite element model of the atlantoaxial bone internal fixation system according to the size data of the atlantoaxial geometric model and a preset internal fixation system attribute table; establishing a model of the internal fixing system according to the attribute of the internal fixing system; and receiving the coupling point selected by the operator, and performing contact setting and assembly on the atlantoaxial geometric model and the internal fixation system model according to the coupling point to obtain the original model.
The atlantoaxial bone is divided into an atlas part and an axis part, and it can be understood that when the atlantoaxial is taken as a whole for simulation analysis, an internal fixing system part needs to be introduced to represent the atlantoaxial fixing condition of a patient, so that the simulation of the atlantoaxial stress of the patient is facilitated; the internal fixing system comprises a bow root screw, a fixing short plate and other parts, and physical parameters of the internal fixing system are determined by referring to materials selected by the screw and the fixing short plate.
The method comprises the steps of establishing an internal fixation system attribute table according to medical research literature and clinical screw selection specifications, presetting the internal fixation system attribute table in computer equipment, directly calling the internal fixation system attribute table when an atlantoaxial geometric model is generated, determining the attribute of the internal fixation system according to the size data of the atlantoaxial geometric model, establishing the attribute of the internal fixation system to establish the internal fixation system model, and assembling the internal fixation system model with the atlantoaxial geometric model to obtain an original model.
In one embodiment, the applying the preset boundary condition and the load characterizing the physiological mechanics of the patient's bone to the original model includes: applying preset constraint on the degree of freedom of a lower surface node of the lower skeleton in the original model to serve as boundary conditions; receiving a reference point selected by said operator above an upper bone of said original model; and applying the load to the reference point, wherein the load comprises an axial compression force and bending moments in different directions so as to simulate the working conditions of axial compression, forward bending, backward extension, lateral bending and torsional movement of the bone of the patient.
The purpose of applying the boundary conditions and the loads is to simulate the stress conditions of the bones of the patient under various motion conditions, so that in one embodiment, the stress conditions are determined according to physiological parameters of the body of the patient, such as height, weight and the like, and further the boundary conditions and the loads to be applied to the original model are determined.
The boundary condition is set by referring to the stress condition of the skeleton, and the aim is to restrict the node set on the lower surface of the model to be completely fixed, so that the model does not shift and rotate under the load condition, and the positive problem of the original model under the preset load is solved.
The method comprises the steps of setting a reference point above an upper skeleton of an original model, selecting all unit nodes on the upper surface of the upper skeleton as a node set, setting coupling connection of the reference point and the node set, and simulating a power transmission working condition of uniform stress of the skeleton under a preset load so as to solve a positive problem of the original model.
In one embodiment, the performing an inversion calculation according to the preset boundary condition, the load, and the boundary displacement data to obtain the physical parameters of the isotropic material includes: taking the geometric model with the set isotropic material as an object model for inversion calculation, and acquiring three-dimensional coordinates of each node of the object model and a connection relation between the nodes; writing the preset boundary condition, the load, the boundary displacement data, the three-dimensional coordinates of the nodes and the connection relation among the nodes into a format file for inversion calculation; taking the format file as an input file, taking the sum of a boundary displacement data related item and a regularization data related item as a target function, taking the target function smaller than a preset threshold value as a convergence condition, and performing inversion calculation according to the input file and a preset condition of an inversion calculation program; and when the objective function meets the convergence condition, obtaining the shear modulus of the isotropic material.
Wherein, as mentioned above, the geometric model of the isotropic material is set and the poisson's ratio of the isotropic material part is also set; therefore, the unknown physical parameters in the object model are only the shear modulus or the elastic modulus of the isotropic material, in the method, the shear modulus is obtained according to calculation, the elastic modulus is obtained according to the shear modulus and the Poisson ratio, and finally the physical parameters of the isotropic material part are determined.
And writing the preset boundary condition, the load, the boundary displacement data, the three-dimensional coordinates of the nodes and the connection relation among the nodes into a format file for inversion calculation.
In one embodiment, the preset conditions of the inversion calculation procedure include: setting the problem of inversion calculation as an incompressible plane problem; setting a regularization constant of the objective function, an initial value of an objective function variable, upper and lower parameter limits and the maximum iteration step number of the objective function.
After the problem of the inversion calculation is set as the problem of the incompressible plane, the corresponding calculation program of the incompressible plane problem can be called to perform the inversion calculation, so that the calculation speed is increased.
Wherein, the upper and lower limits of the parameter refer to the upper and lower limits of the shear modulus, and the maximum iteration step number refers to the maximum number of times of optimization iteration after the inverse problem is converted into the optimization problem; constraint conditions such as a regularization constant of the target function are preset, so that normal solving and normal ending of the inversion calculation process can be ensured, and the solving result is ensured not to have singularity.
In one embodiment, the calculation result data of the positive problem is arranged into a format which can be used for calculation, a plurality of different material parts in the geometric model are set to be an incompressible elastic material, and the Poisson ratio is set; setting a calculation program of the inverse problem as a calculation program of the problem of the incompressible elastic material, setting an objective function and related constraint conditions and convergence conditions, operating a Python program to write the data into an in-format file for inverse problem calculation, and calculating in the environment of a Linux system; importing the in file into an inversion program, calculating a target function, judging whether the result meets the set target function convergence condition, if so, ending iteration, outputting the shear modulus obtained by inversion calculation, and if not, continuing the iteration calculation; until the objective function meets the convergence condition or reaches the maximum iteration step number; and when the maximum iteration step number is reached, outputting the shear modulus calculated by the maximum iteration step number.
In one embodiment, the assigning physical parameters of the isotropic material to the geometric model to obtain a bone model capable of characterizing the physiological-mechanical characteristics of the original model includes: calculating to obtain an elastic modulus according to the shear modulus and the Poisson ratio of the isotropic material; and giving the elastic modulus and the shear modulus to a material part set as the isotropic material in the geometric model to obtain the bone model.
Wherein, because the isotropic material has less physical parameters, the material property of the isotropic material can be represented according to three physical parameters of Poisson ratio, shear modulus and elastic model, and the shear modulus and the elastic modulus are two material parameters which can be mutually converted, the shear modulus which is obtained by inverse calculation and is set as the different material parts of the isotropic material needs to be converted into the elastic modulus, then the corresponding shear modulus, elastic modulus of one or more isotropic materials and the Poisson ratio which is synchronously set when the isotropic material is set are given to the material parts which are set as different isotropic materials in the geometric model together, compared with the original model, the inhomogeneous material in the original model is simplified into one, two or more isotropic materials, and the simplified model which can represent the physiological and mechanical characteristics of the original model is obtained, i.e. a model of the bone.
In one embodiment, the original model and the bone model are finite element models of lumbar vertebrae, the finite element models comprise three structural parts, namely an upper vertebral body L1, a lower vertebral body L2 and an intervertebral disc, simulation analysis is carried out on the original model and the bone model under the same boundary conditions and loads, and the displacement of the simplified bone model and the displacement of the complete original model in three directions under the same boundary conditions are basically consistent (shown in table 1), so that the simplified bone model can represent the physiological and mechanical characteristics of the original model in the simulation analysis.
Figure BDA0003136334700000101
TABLE 1 Displacement comparison Table for original model and bone model
In the embodiment, the effectiveness of the simplified bone model is independently verified, the bone model is subjected to simulation analysis under different working conditions to obtain displacement data and corner change data of the bone model, and the displacement data and the corner change data are compared with experimental data of an existing medical experiment.
The displacement data and the comparison data of the bone model under the axial compression load are shown in table 2, the displacement data obtained by simulation analysis is approximately linear, and the displacement value is in the displacement variation range of the similar experiment and is close to the minimum displacement value in the result curve data of the similar Brown experiment. The fact proves that the simplified lumbar model established on the basis of the parameters obtained by inverse problem calculation can be used for simulating and analyzing the stress deformation condition of the real human lumbar under the axial compression condition.
Figure BDA0003136334700000102
TABLE 2 skeleton model axial load-displacement change table (mm)
The effectiveness of the skeleton model is verified by simulating the activity of the skeleton model under the conditions of anteflexion, extension, lateral bending and torsion motions. And analyzing the size and the variation trend of the turning angle of the vertebral body, and proving the effectiveness of the bone model in simulation analysis. When 500N axial compression force and 7.5Nm bending moment are applied, the mobility contrast data of the vertebral body under various working conditions is shown in FIG. 2, and it can be seen that the rotation angle measured by the simulation experiment in the embodiment is similar to the data of the similar experiment.
Therefore, according to the comparison result of the simulation data of the bone model and the original model and the comparison result of the simulation data of the existing medical research in the embodiment, the simplified bone model can represent the physiological and mechanical characteristics of the original model in the simulation analysis, is effective in the medical sense, and can be used for more complex operation and simulation analysis, such as the topology optimization design of a bone treatment instrument.
As shown in fig. 3, in an embodiment, there is provided an optimal design method of a bone treatment instrument, which specifically includes the following steps:
Step 302, determining the size of the bone medical instrument according to the position of the bone medical instrument to be implanted into the patient, taking the size of the bone medical instrument as the size of a design domain, and establishing a finite element model of the design domain according to the size of the design domain.
The bone medical instrument is a medical instrument which performs treatment in a patient body by an implantation method when treating bone diseases, and the implantation position of the bone medical instrument is determined by a treatment scheme formulated by a clinician; and determining the style and the size of the bone medical instrument according to the implantation position, the physiological and pathological data of the bone of the patient at the implantation position and the operation mode in the treatment scheme.
The design domain is a model space region of an optimization design, and the structure obtained in the design domain according to the design variables is continuously optimized by performing iterative computation on the design variables until the convergence conditions of a preset constraint function and a preset objective function are met, so that the optimal solution of the design variables is obtained, and the optimal structure is obtained.
It can be understood that the size of the bone medical instrument is matched with the physiological and pathological data of the bone of the patient at the implantation position, and the length, the width and the height indexes of the bone medical instrument selected clinically are referred to, so that the condition that the bone of the patient at the implantation position is too large or too small is avoided; the optimal design in the size range of the bone medical instrument can avoid the problem that the optimal design result is not matched with the actual physiological and pathological environment of a patient.
The method has the advantages that the method is low in cost, high in repeatability, convenient for parametric research and the like; in the meshing step of establishing the finite element model of the design domain, a smaller mesh size can be set so as to obtain a clearer and more detailed stress change condition.
And 304, assembling the design domain finite element model to a target bone model to obtain a design domain implantation model, wherein the target bone model is a finite element model established according to actual scanning data of the bone part to be treated of the patient.
The method comprises the steps of dividing a surface mesh and a body mesh of a finite element model of a design domain in modeling software, checking the quality of the mesh, setting the material property of the finite element model of the design domain, setting the contact, and the like, and finally selecting the finite element model of the design domain and a target skeleton model to assemble according to a preset implantation position to obtain the implantation model of the design domain.
It should be noted that the design domain finite element model is a simplified model established based on the size of the bone medical instrument, the sharp tooth structure of the surface contacting with the bone is omitted from the model, and the surface of the established model is flat and smooth. The function of the sharp teeth is to form fixation and prevent slippage between the bone medical instrument and the bone, so the contact property of the finite element model of the design domain and the target bone model is set as binding contact, thereby replacing the function of the surface sharp tooth structure.
It will be understood that the target bone model is a complete finite element model, and may be a non-uniform material model with different material properties for each model portion, for example, the original model constructed above, or a uniform material model equivalent to the non-uniform material model, for example, the simplified bone model constructed above, or of course, other models processed by the prior art that can be used as simulation calculations. The uniform material model equivalent to the non-uniform material model can obtain an accurate and effective simulation analysis result with less calculation amount.
Step 306, determining a topology optimization method, and receiving constraint conditions, objective functions, boundary conditions, loads and design variables set by an operator under an optimization framework of the topology optimization method, wherein the design variables are unit density, structural boundaries or structural parameters of the movable deformable component.
The existing optimization design method can be divided into size optimization, shape optimization and topology optimization, and the topology optimization can change not only the material layout of the structure but also the size and shape of the structure. Of the three optimization methods, the topology optimization technology aiming at seeking the optimal material distribution has become an important component of the modern structural design platform based on the creative design capability. Therefore, the method adopts a topological optimization means to carry out optimization design on the design domain so as to obtain the optimal topological structure of the bone medical instrument.
Different topological optimization methods comprise different optimization frames and optimization columns, so before solving the problem of the optimal topological structure, corresponding design variables, optimization structures and optimization columns need to be determined according to the topological optimization methods, and then constraint conditions, objective functions and the optimization columns are combined to obtain specific calculation columns. And the boundary conditions and the loads are applied to the design domain implantation model to simulate the motion conditions of the bone medical instrument after the bone medical instrument is implanted into the corresponding bone part, so as to calculate whether the structure of the bone medical instrument under the current design variables meets the constraint conditions and the objective function.
And 308, solving an optimization problem established according to the constraint condition, the objective function, the boundary condition, the load, the design variable and the design domain implantation model to obtain an optimal topological structure of the bone medical instrument.
The optimal solution of the solved optimization problem is a set of design variables which accord with constraint conditions and an objective function, the design variables and the structure of the bone medical instrument have a fixed corresponding relation, namely the design variables of the optimal solution correspond to the optimal topological structure, if the design variables are length, width and height, and the optimal solution is (1, 1, 1), the corresponding optimal topological structure is a cube with the side length of 1, and it can be understood that the design variables of the topological optimization method in practical application are much more complex.
According to the optimal design method of the bone medical instrument, firstly, the size of the bone medical instrument is determined according to the position of a patient to be implanted into the bone medical instrument, the size of the bone medical instrument is used as the size of a design domain, and a finite element model of the design domain is established according to the size of the design domain; assembling the design domain finite element model to a target skeleton model to obtain a design domain implantation model, wherein the target skeleton model is a finite element model established according to actual scanning data of the to-be-treated skeleton part of the patient; then determining a topological optimization method, and receiving constraint conditions, objective functions, boundary conditions, loads and design variables set by an operator under an optimization framework of the topological optimization method, wherein the design variables are unit density, structural boundaries or structural parameters of a movable deformable component; and solving an optimization problem established according to the constraint condition, the objective function, the boundary condition, the load, the design variable and the design domain implantation model to obtain the optimal topological structure of the bone medical instrument. According to the invention, the design domain model is assembled on the target skeleton model to be treated by the patient, and the topology optimization of the design domain model is carried out under the applied boundary condition and load, so that the optimal topology model conforming to the constraint condition and the target function is obtained, the problem that the standard skeleton medical instrument in the traditional scheme is not matched with the physiological and pathological conditions of the patient is solved, and the stability and the safety of the skeleton medical instrument during actual treatment are improved.
In one embodiment, the sizing the bone medical device based on a location in a patient where the bone medical device is to be implanted includes: according to the position of the bone medical instrument to be implanted into the patient, acquiring the size of the standard bone medical instrument implanted into the position in a general treatment scheme; comparing the space size of the position capable of accommodating the bone medical instrument with the size of the standard bone medical instrument to obtain a comparison result; and adjusting the size of the standard bone medical instrument according to the comparison result, and taking the adjusted size of the standard bone medical instrument as the size of the bone medical instrument so as to enable the size of the bone medical instrument to be matched with the physiological condition and the pathological condition of the bone to be treated of the patient.
After the implantation position is determined according to the treatment scheme, the size of a design domain is further determined by referring to the style and the size of standard bone medical instruments used at similar implantation positions in a common treatment scheme; and carrying out optimization design on the basis of the size of the standard skeleton medical instrument. On one hand, the standard skeleton medical instrument is an effective style and size which are medically verified, but is possibly not matched with the actual physiological and pathological conditions of a patient, and still has important reference value; on the other hand, because the existing supporting facilities, such as the holder and the trial body device, are adapted to the standard bone medical instrument, if the structure, the style or the size of the bone medical instrument obtained by the optimal design is too large different from the standard bone medical instrument, the difficulty of implantation treatment and the risk of operation are increased.
When the design domain finite element model is established, the size of the standard skeleton medical instrument cannot be directly adopted as the size of the design domain, and the design domain needs to be adjusted according to the actual physiological and pathological data of the skeleton of the patient so as to be matched with the actual physiological and pathological conditions of the patient.
In one embodiment, the patient has differences in the size of the left and right atlanto-axial lateral mass joint gaps, with the left side joint gap averaging 3.8mm and the right side averaging 3.0 mm. With reference to the measured left and right gap height values, the height value of the right design field was set to 4.3mm and the height value of the left design field was set to 3.5 mm. The height of the bone medical instrument is set to be slightly higher than the height of the gap, so that the overall biomechanical stability can be improved after the bone medical instrument is implanted, and the position fixation of the bone medical instrument is facilitated.
In one embodiment, after said obtaining the optimal topology of the bone medical device, the method further comprises: establishing a finite element model of the bone medical instrument according to the optimal topological structure; assembling the bone medical instrument finite element model to the target bone model to obtain a simulated treatment model; carrying out simulation analysis under preset boundary conditions and loads on the simulation treatment model, and evaluating the mechanical property of the finite element model of the bone medical instrument; and when the mechanical property meets the preset requirement, determining the usability of the finite element model of the bone medical instrument.
Before obtaining the optimal topological structure and manufacturing the bone medical instrument according to the optimal topological structure for medical use, validity verification is required; therefore, a finite element model of the bone medical instrument is established according to the optimal topological structure, and is assembled to a target bone model after conventional processing such as grid division, material attribute setting, grid quality inspection and the like, so as to perform mechanical analysis of simulation treatment as a whole.
And carrying out simulation analysis on the simulation treatment model under preset boundary conditions and loads to obtain stress distribution data of the bone medical instrument model, stress distribution data of the target bone model and displacement data of the bone medical instrument model, and evaluating the mechanical property of the finite element model of the bone medical instrument by taking the maximum stress borne by the bone medical instrument model and the target bone model and the maximum displacement of the bone medical instrument model as indexes for evaluating the anti-subsidence capacity.
And when the mechanical property meets the preset requirement, determining the effectiveness of the bone medical instrument finite element model, and manufacturing the bone medical instrument according to the bone medical instrument finite element model.
In one embodiment, when the design variable is cell density, the topological optimization method is a variable density method, a homogenization method or a progressive optimization method; when the design variable is a structural boundary, the topological optimization method is a level set method; when the design variable is a movable deformable component, the topological optimization method is a movable deformable component method.
The homogenization method comprises the steps of dividing a plurality of microstructures with units with holes in a design domain, carrying out topology optimization on a continuum, and representing the microstructures of empty holes, entities and holed entities by taking the hole size and hole azimuth angle of a microstructure unit cell as design variables; the homogenization method relaxes the material density by microstructure parameters so that the cell density can be continuously valued at [0,1], where the cell density is a function of the opening size.
The progressive optimization method is to make the remaining structure tend to be optimized by gradually deleting invalid material units, and the design variables are discrete unit densities, which are respectively 0 and 1, and represent the existence or nonexistence of the corresponding units.
The level set method is a structure body in which design variables are structural boundaries, which is described by an implicit level set function.
In one embodiment, when the topology optimization method is a variable density method, the design variable is a density value of each unit, and the solving an optimization problem established according to the constraint condition, the objective function, the boundary condition, the load, the design variable and the design domain implant model to obtain the optimal topology of the bone medical device comprises: calculating to obtain a unit stiffness matrix of the finite element model of the design domain according to the interpolation model of the variable density method and the current design variable, and combining the unit stiffness matrix into a total stiffness matrix; under the action of the boundary conditions and the loads, carrying out finite element analysis on the design domain finite element model in the design domain implantation model to obtain structural displacement data; calculating a function value and sensitivity of a constraint function in the objective function and the constraint condition according to the structural displacement data and the total stiffness matrix; taking the sensitivity and the function value as input conditions of a moving asymptote algorithm, solving and calculating the optimization problem, and updating the design variable; when the solution calculation result of the optimization problem does not accord with the convergence condition of the objective function, taking the updated design variable as the current design variable, and returning to the step of calculating the element stiffness matrix of the finite element model of the design domain according to the interpolation model of the variable density method and the current design variable; and when the solving calculation result of the optimization problem meets the convergence condition of the objective function, outputting the updated design variable to obtain the optimal topological structure of the bone medical instrument.
Wherein, the variable density method assumes the material density inside the unit as a constant, and the density of each unit of the finite element model is taken as the topological optimization method of the design variable during calculation; when the constraint conditions and the objective function are met, ending the iteration process, reserving units with the density larger than a set value, removing redundant units, and forming the optimal topology of the structure by the residual entity material units; for the interpolation model of the variable density method and the specific calculation formula of the moving asymptote algorithm (MMA algorithm), refer to the prior art.
In practical application, the optimization design of the variable density method can be directly carried out by a topological optimization functional module of modeling software. In one embodiment, the design domain finite element model and the target bone model are imported into the Abaqus software for optimal design. In order to obtain a bone medical instrument structure which meets the size constraint of the volume and the strength requirement, the flexibility of an optimized target structure is set to be minimum, the constraint condition is the volume upper limit of a solid material, and topology optimization design is carried out. The bone medical instrument structure which meets the structural rigidity requirement and is stressed uniformly under the volume constraint can be obtained.
In this embodiment, under global volume constraints, when developing a topology-optimized design of a bone medical instrument in a variable-density framework, the design variable is the material unit density ρ ═ (ρ ═ 1,ρ2,ρ3,…,ρn)TN is the number of units, corresponding extensionThe optimal flapping formula is:
Findρ＝(ρ1,ρ2,ρ3,…,ρn)T∈D
Figure BDA0003136334700000143
s.t.
Figure BDA0003136334700000141
KU＝F
0<ρmin≤ρi≤1,(i＝1,2,…,n)
where ρ isiThe value of the design variable for the material unit density, namely the topological optimization problem calculation is [ rho ]min,1]A continuous value in between, where pminThe value is typically a minimum value close to "0"; d is the entire structural design domain;
Figure BDA0003136334700000142
a volume upper limit value set for the fusion cage; v*Representing the volume of the fuser after topological optimization. C represents the overall flexibility of the fusion device, F represents an external load vector, and K and U represent an overall rigidity matrix and a displacement column vector of the structure respectively.
In one embodiment, when the topology optimization method is a mobile deformable component method, the design variables are structural parameters determining components in the mobile deformable component method, and the solving an optimization problem established according to the constraint conditions, the objective function, the boundary conditions, the load, the design variables and the design domain implant model to obtain an optimal topology of the bone medical device includes: under the action of the boundary conditions and the loads, carrying out finite element analysis on the design domain finite element model in the design domain implantation model to obtain analysis result data; calculating a topological description function value of a region of the finite element model of the design domain occupied by each component and a HerveSade function value corresponding to the topological description function value according to the analysis result data and the current design variable; calculating and generating a rigidity matrix and a quality matrix according to the topological description function value and the Hervesseld function value; calculating to obtain a function value and sensitivity of the target function and a constraint function in the constraint condition according to the rigidity matrix and the quality matrix; taking the sensitivity and the function value as input conditions of a moving asymptote algorithm, solving and calculating the optimization problem, and updating the design variable; when the calculation result of the optimization problem does not meet the convergence condition of the objective function, the updated design variable is used as the current design variable, and the step of calculating the topological description function value of the finite element model region of the design domain occupied by each component according to the analysis result data and the current design variable and the Hervesseld function value corresponding to the topological description function value is returned to be executed; and when the solving calculation result of the optimization problem meets the convergence condition of the objective function, outputting the updated design variable to obtain the optimal topological structure of the bone medical instrument.
The basic idea of the movable deformable component method optimization is to use a group of movable deformable components as basic components for completing structural optimization, as shown in fig. 4, in a given design domain, the basic components are freely moved, deformed, rotated, overlapped and covered and fused to realize structural topology change, the positions, the inclination angles, the lengths and the sizes of the components are changed in the optimization process, and the components are overlapped to form an optimal structural topology structure in the design domain when the optimization is finished.
The mobile deformable component method uses the displayed topological description function, so that the number of design variables is reduced, an optimized structure with explicit geometric parameters can be obtained, the optimized target can be more accurately geometrically set to control the size of the structure, the cooperative work with a CAD system is more convenient, and additive manufacturing means such as 3d printing and the like are facilitated.
In one embodiment, the bone medical device design employs a topological optimization formula as follows, selecting structural compliance as an objective function, and imposing constraints on the upper volume limit. The topological optimization formula corresponding to neglecting the volume force is as follows:
Find D,u(x)
Figure BDA0003136334700000151
s.t.
Figure BDA0003136334700000152
Figure BDA0003136334700000153
Figure BDA0003136334700000154
Figure BDA0003136334700000155
Figure BDA0003136334700000156
where D represents the entire design domain, Ω represents the entity domain, g jRepresenting the jth constraint function, t is the Neumann boundary F of the structuretThe force of the upper surface of the steel,
Figure BDA0003136334700000157
is Dirichlet boundary gammauAnd (3) is detected. Further, u and v are displacement fields and are defined in
Figure BDA0003136334700000158
Heuristic function of and satisfies
Figure BDA0003136334700000159
ε is the second order linear responseThe amount of the variation is.
Figure BDA00031363347000001510
(
Figure BDA00031363347000001511
And δ is the fourth and second unit tensors, respectively) is the fourth order elastic tensor of the isotropic material that constitutes the solid material[26]E is the Young's modulus of the material, v is the Poisson's ratio of the material,
Figure BDA00031363347000001512
is the volume upper bound value of the solid material.
For the design of bone medical devices, design variables when using the MMC method
Figure BDA0003136334700000162
Design variables for components that can determine structural layout
Figure BDA0003136334700000163
Wherein
Figure BDA0003136334700000161
Represents the center coordinate, the semi-axis length, the rotation angle and the thickness of the component of the ith component.
As shown in fig. 5, fig. 5 is a flowchart for solving an optimization problem by applying a movable deformable component method, because the established target skeleton model has an irregular shape and a complex structure and load condition, if the Python program is directly applied to analyze and calculate the whole model by using the movable deformable component method, the program processing workload is large and the time consumption is long. Therefore, simulation analysis of the complex model needs to be completed by using Abaqus software, simulation data such as stress strain, displacement, boundary information, contact, geometric volume elements and the like are obtained and are generated into an inp file, and then topology optimization design is performed on the structure by using Python language and adopting an explicit movable deformable component method.
The specific process of the topology optimization design is as follows: initializing a design variable D according to the simulation result data in the inp file and the initial design variableD, calculating a topological description function value χ of the area of the finite element model of the design domain occupied by each components(x) And Hervesseld function values H (χ) corresponding to said topology description function valuess(x) According to the topology description function value χ), then according to the topology description function value χs(x) And the Hervesseld function value H (χ)s(x) Computing a stiffness matrix K and a mass moment M, and computing an objective function value f according to the stiffness matrix K and the mass moment M0val and sensitivity, and a function value and sensitivity of a constraint function in the constraint condition; taking the sensitivity and the function value as input conditions of a mobile asymptote algorithm (MMA algorithm), solving and calculating the optimization problem, and updating the design variable; when the solving calculation result of the optimization problem does not accord with the convergence condition of the objective function, the updated design variable is used as the current design variable, and the topological description function value chi is recalculateds(x) And the Hervesseld function value H (χ)s(x) Performing an iterative loop; and stopping the calculation until the calculation result of the optimization problem meets the convergence condition of the objective function, and outputting the updated design variable. For a specific calculation formula of the moving asymptote algorithm, reference is made to the prior art.
In one embodiment, the bone medical device is an intervertebral cage; the constraints further include: bone graft fusion constraint; receiving constraint conditions set by an operator, comprising the following steps: and receiving the upper and lower limits of the stress borne by the bone grafting part of the interbody fusion cage set by the operator as the bone grafting fusion constraint, so that the stress borne by the bone grafting part meets the growth requirement of bone spurs, and the stress shielding of the bone grafting part by the fusion cage is avoided.
As shown in fig. 6, fig. 6 is an optimized topology of the intervertebral cage designed optimally in one embodiment, and a hollow space region of the intervertebral cage is called a bone grafting window, and is filled with bone grafting material to form a bone grafting part, and after the intervertebral cage is implanted into a patient, the bone grafting part is contacted with the bone of the patient, and the bony fusion is performed under appropriate stress stimulation.
The osseous fusion is the key of the intervertebral fusion and determines the success or failure of the operation, so that the upper and lower limits of the bearing stress of the bone grafting part can be restrained, and the stress of the bone grafting part is ensured to be in a proper range in the simulation process and practical application of the intervertebral fusion device structure obtained according to the optimized design.
In one embodiment, the constraints further include: constraining the outer contour; receiving constraint conditions set by an operator, comprising the following steps: and receiving the outer contour parameters of the bone medical instrument set by the operator as the outer contour constraint, so that the finally obtained optimal topology result can be adapted to the matching device of the existing bone medical instrument.
The result of the topology optimization design may be an irregular shape, which is not adapted to the existing kit of the bone medical device, and if the kit is formulated according to the optimal topology, the medical cost is greatly increased, while the surgical risk is increased by using the non-adapted kit, such as a holder or a trial device. Therefore, the outer contour of the optimized design result needs to be constrained to be adapted to the matching device of the standard bone medical instrument.
As shown in fig. 7, in one embodiment, there is provided an interbody cage manufacturing method applied to an interbody cage manufacturing system including an input device, a display device, a processor device, and a manufacturing device, wherein the input device, the display device, and the manufacturing device are respectively connected to the processor device; the method specifically comprises the following steps:
And 702, inputting the patient vertebra scanning data into the processor device by the input device, and modeling and simplifying the patient vertebra scanning data by the processor device to obtain a vertebra finite element simplified model.
The input device may be a computer device, or may be another device having both a calculation processing function and a medical scanning function. The processor device is a computer device.
The processor device establishes a vertebra original model according to the scanning data of the patient vertebra in modeling software, and obtains a vertebra finite element simplified model after simplifying the vertebra original model.
Step 704, the input device inputs the patient's vertebra physiopathological parameters and the treatment plan to the processor device, and the processor device establishes a finite element model of the intervertebral cage design domain according to the physiopathological parameters and the treatment plan.
The physiological and pathological parameters of the vertebrae of the patient refer to parameters of the vertebrae which can be directly measured, such as the number of the vertebrae, the size data of each vertebra, the average distance between two vertebrae, and the like, and derived pathological parameters, such as abnormal data which is derived as the intervertebral disc protrusion between the seventh vertebra and the eighth vertebra, and the like.
The treatment scheme is a treatment scheme which is made by a clinician according to the existing physiological and pathological parameters and comprises an implantation position, an implantation angle, a predicted size pattern and the like of the intervertebral fusion device.
The style and the size of the adopted interbody fusion cage can be determined according to the physiological and pathological parameters and the treatment scheme, a finite element model of a design domain of the interbody fusion cage is further established, and the individualized optimization design of the interbody fusion cage is carried out on the basis.
Step 706, the processor device establishes an optimization problem according to the physiological and pathological parameters, the finite element model of the designed domain of the interbody fusion cage and the finite element simplified model of the vertebra, and solves the optimization problem by adopting a preset topological optimization method to obtain an optimal topological structure.
Wherein, according to the physiological and pathological parameters, the property requirements of the interbody fusion cage can be determined, namely the constraint condition and the objective function in the optimization problem are determined; and continuously and iteratively calculating whether the intervertebral fusion device structure represented by the design variable meets the constraint condition and the objective function under the preset boundary condition and load.
And 708, the processor device establishes a finite element model of the interbody fusion cage according to the optimal topological structure, and transmits the finite element model of the interbody fusion cage to the display device for displaying, so that a clinician confirms the usability of the finite element model of the interbody fusion cage.
Wherein, the display device is a screen device, and can output images for a clinician to confirm the usability of the finite element model of the interbody fusion cage.
And judging whether the finite element model of the interbody fusion cage is available or not by a clinician according to whether the structure and the size of the finite element model of the interbody fusion cage meet the medical requirements and the requirements of a treatment scheme or not and according to simulation analysis data after the finite element model of the interbody fusion cage and the vertebral finite element simplified model are assembled.
Step 710, the processor device sends a manufacturing instruction to the manufacturing device after receiving the message that the clinician confirms that the finite element model of the interbody fusion cage is available, wherein the manufacturing instruction comprises the finite element model of the interbody fusion cage.
Wherein the clinician feeds back a confirmation message to the processor device after determining that the finite element model of the interbody cage is available.
By manufacturing device is meant, among other things, a device with additive manufacturing functionality, such as a 3D printer.
And 712, the manufacturing device manufacturing the intervertebral cage based on the finite element model of the intervertebral cage after receiving the manufacturing instruction.
Wherein, after the personalized interbody fusion cage is manufactured, the interbody fusion cage can be put into clinical use only after medical process treatment.
It is worth mentioning that the atlantoaxial anatomy structure is complex and has large variation, which causes difficulty in the design of the intervertebral fusion cage; in addition, the operation for placing the atlantoaxial lateral mass joint fusion cage is complex, and the surrounding important tissue structures can be damaged by carelessness, which also puts higher design requirements on the functionality and the applicability of the lateral mass intervertebral fusion cage. Compared with a standard interbody fusion cage, the interbody fusion cage obtained by adopting the topology optimization method enables a clinician to have more implantation positions and angle selections when formulating a treatment scheme, and can reduce the operation difficulty to a certain extent.
According to the manufacturing method of the interbody fusion cage, the scanning data of the patient vertebrae are input into the processor device through the input device, and the processor device carries out modeling and simplification according to the scanning data of the patient vertebrae to obtain a finite element simplified model of the vertebrae; the input device inputs the physiological and pathological parameters and the treatment scheme of the vertebra of the patient into the processor device, and the processor device establishes a finite element model of the design domain of the intervertebral fusion device according to the physiological and pathological parameters and the treatment scheme; the processor device establishes an optimization problem according to the physiological and pathological parameters, the intervertebral fusion device design domain finite element model and the vertebra finite element simplified model and solves the optimization problem by adopting a preset topological optimization method to obtain an optimal topological structure; the processor device establishes a finite element model of the interbody fusion cage according to the optimal topological structure, and transmits the finite element model of the interbody fusion cage to the display device for displaying, so that a clinician confirms the availability of the finite element model of the interbody fusion cage; the processor equipment sends a manufacturing instruction to the manufacturing equipment after receiving the message that the clinician confirms that the finite element model of the interbody fusion cage is available, wherein the manufacturing instruction comprises the finite element model of the interbody fusion cage; the manufacturing device, upon receiving the manufacturing instructions, manufactures the interbody cage based on the interbody cage finite element model. According to the invention, the design domain in the combined model of the vertebrae and the intervertebral fusion cage design domain is topologically optimized by a topological optimization method, so that an optimal intervertebral fusion cage structure meeting the physiological and pathological conditions of the patient and the requirements of a treatment scheme is obtained, and finally, the personalized intervertebral fusion cage matched with the physiological and pathological conditions of the patient is manufactured according to the optimal topological structure, so that the problem that the standard intervertebral fusion cage in the traditional scheme is not matched with the physiological and pathological conditions of the patient is solved, the safety and the stability of the intervertebral fusion cage are improved, and the treatment effect of the intervertebral fusion cage is improved.
In one embodiment, the processor device performs finite element modeling and simplification based on the patient vertebrae scan data to obtain a vertebrae finite element simplified model, including: the processor device carries out geometric modeling according to the scanning data of the skeleton of the patient to obtain a geometric model, and sets corresponding physical parameters for different material parts in the geometric model to obtain an original model; the processor equipment applies preset boundary conditions and loads representing the physiological mechanics of the skeleton of the patient to the original model, and performs simulation analysis to obtain boundary displacement data of the original model; the processor equipment receives the setting operation of an operator, sets the different material parts in the geometric model as at least one isotropic material according to the setting operation, and performs inversion calculation according to the preset boundary condition, the load and the boundary displacement data to obtain the physical parameters of the isotropic material; the processor device assigns physical parameters of the isotropic material to the geometric model to obtain a vertebral finite element simplified model.
The technical features of the processor device for modeling and simplifying according to the patient vertebra scanning data are consistent with the technical feature contents of the bone model construction method in the present specification, and are not described herein again.
In one embodiment, the processor device builds an intervertebral cage design domain finite element model based on the physiopathological parameters and the treatment plan, including: the processor equipment acquires the size of the standard bone medical instrument implanted at the position in a general treatment scheme according to the position of the bone medical instrument to be implanted into the patient in the treatment scheme; the processor equipment compares the space size of the position capable of accommodating the bone medical instrument with the size of the standard bone medical instrument to obtain a comparison result, wherein the space size of the position capable of accommodating the bone medical instrument is determined according to the physiological and pathological parameters; the processor equipment adjusts the size of the standard bone medical instrument according to the comparison result, and takes the adjusted size of the standard bone medical instrument as the size of the bone medical instrument so as to enable the size of the bone medical instrument to be matched with the physiological condition and the pathological condition of the bone to be treated of the patient; and the processor device takes the size of the bone medical instrument as the size of a designed domain of the intervertebral fusion cage, and establishes a finite element model of the designed domain of the intervertebral fusion cage according to the size of the designed domain of the intervertebral fusion cage.
The technical features of the finite element model of the designed domain of the intervertebral fusion cage established by the processor device according to the physiological and pathological parameters and the treatment scheme are consistent with the technical feature content of step 302 in the optimization method of the bone medical instrument in the present specification, and are not described herein again.
In one embodiment, the processor device establishes an optimization problem according to the physiopathological parameters, the finite element model of the designed domain of the interbody fusion cage and the finite element simplified model of the vertebrae, and solves the optimization problem by using a preset topological optimization method to obtain an optimal topological structure, including: the processor equipment assembles the intervertebral fusion cage design domain finite element model to the vertebra finite element simplified model to obtain a design domain implantation model; the processor device receives a constraint condition, an objective function, a boundary condition, a load and a design variable set by an operator under an optimization framework of the preset topological optimization method, wherein the constraint condition, the objective function, the boundary condition, the load and the design variable are set according to the physiological and pathological parameters and the preset topological optimization method; wherein the design variable is a cell density, a structural boundary, or a structural parameter of a moving deformable component; and the processor equipment solves an optimization problem established according to the constraint condition, the objective function, the boundary condition, the load, the design variable and the design domain implantation model to obtain the optimal topological structure of the interbody fusion cage.
The processor device establishes an optimization problem according to the physiological and pathological parameters, the finite element model of the designed domain of the interbody fusion cage and the simplified finite element model of the vertebrae, and solves the optimization problem by using a preset topological optimization method to obtain the technical characteristics of the optimal topological structure, which are consistent with the technical characteristics of the step 304 to the step 308 in the optimization method of the bone medical instrument in the specification and are not repeated here.
In one embodiment, the processor device establishes a finite element model of the interbody fusion cage according to the optimal topology and transmits the finite element model of the interbody fusion cage to the display device for display, including: the processor device establishes a finite element model of the interbody fusion cage according to the optimal topological structure; the processor equipment assembles the intervertebral fusion cage finite element model to the vertebra finite element simplified model to obtain a simulation treatment model; the processor equipment performs simulation analysis under preset boundary conditions and loads on the simulation treatment model, and evaluates the mechanical property of the finite element model of the bone medical instrument; and when the mechanical property meets the preset requirement, the processor device transmits the finite element model of the interbody fusion cage to the display device for displaying.
Before the optimal topological structure is obtained and the intervertebral fusion cage is manufactured according to the optimal topological structure and put into medical use, validity verification is required; therefore, the intervertebral fusion cage finite element model is established according to the optimal topological structure, and is assembled to the vertebra finite element simplified model after conventional processing such as grid division, material attribute setting, grid quality inspection and the like, and the mechanical analysis of simulation treatment is carried out as a whole.
And carrying out simulation analysis on the simulation treatment model under preset boundary conditions and loads to obtain stress distribution data of the interbody fusion cage model, stress distribution data of the vertebra finite element simplified model, stress distribution data of the bone grafting part and displacement data of the interbody fusion cage model, and evaluating the mechanical property of the interbody fusion cage finite element model by taking the maximum stress borne by the interbody fusion cage model, the bone grafting part and the vertebra finite element simplified model and the maximum displacement of the interbody fusion cage model as indexes for evaluating the subsidence prevention capacity.
In one embodiment, the traditional bullet-type fusion Cage model Cage D and the individualized intersomatic fusion Cage finite element model Cage E obtained by the optimization design are mechanically evaluated at the same time, the two models are assembled at the same position in the same atlantoaxial finite element model at the same angle, the same boundary conditions and loads are applied to the whole simulation treatment model, and the mechanical evaluation results are shown in table 3.
CageD CageE
Maximum stress value (MPa) of fusion cage 7.888 5.489
Maximum stress value of vertebral body (MPa) 3.221 3.034
Maximum stress value (MPa) of bone graft 0.7607 0.8440
Fusion cage displacement peak value (mm) 0.07102 0.07109
Model integral displacement peak value (mm) 0.1371 0.09745
TABLE 3 atlas and axis fusion device mechanics evaluation comparison table
As can be seen from the data in Table 3, the personalized cage CAGEE has a vertebral body portion maximum stress value of 3.034MPa, which is less than the vertebral body maximum stress value of 3.221MPa for a conventional cage implant; the peak value of the overall model displacement of the cageD implanted into the traditional cage is 0.1371mm, while the peak value of the overall model displacement of the cagE implanted into the traditional cage is 0.09745mm, and the peak value of the displacement of the implanted model of the traditional cage is obviously higher than that of the cagE implanted into the individually designed cage.
From more detailed stress distribution data, the stress distribution of the contact surface of the vertebral body and the fusion device is consistent with the stress distribution position of the fusion device, and the maximum stress is mainly distributed at the contact position of the edge of the fusion device. The personalized cage E is relatively uniform in stress distribution state, and stress concentration is not generated. The bone grafting volume of the traditional cage cageD is about 65.48%, and the bone grafting volume of the novel lateral mass cage is about 67.03% higher than that of the traditional cage. During the backward extension movement, the maximum stress is mainly distributed on the surface contacting with the vertebral body according to the stress distribution state of the bone grafting surfaces of the two lateral mass fusion devices, wherein the personalized fusion device cagE has larger bone grafting stress distribution area and more uniform stress distribution, and can stimulate the bone grafting of the stress distribution area to be fused with the vertebral body more quickly in a benign way.
It can be seen that, in the present embodiment, the individually designed intervertebral cage can improve the stability of the vertebral body and reduce the risk of subsidence of the intervertebral cage compared to the conventional intervertebral cage.
The preset requirements are set according to the existing medical research data, and whether the data of the mechanical evaluation result meet the expected treatment effect in the treatment scheme or not is judged by taking the existing medical research data as reference.
In one embodiment, the manufacturing device, upon receiving the manufacturing instruction, manufactures the interbody cage based on the interbody cage finite element model, comprising: the manufacturing equipment performs material increase manufacturing on the interbody fusion cage according to the finite element model of the interbody fusion cage to obtain an initial interbody fusion cage; and the manufacturing equipment is used for grinding, polishing and carrying out medical treatment on the initial interbody fusion cage according to preset medical requirements and process requirements to obtain the interbody fusion cage.
Among them, the interbody fusion cage is a medical instrument that needs to be implanted into a patient, and needs to be handled and stored by a special medical means to avoid complications caused by other factors.
As shown in fig. 8, in one embodiment, there is provided a bone model construction apparatus, the apparatus comprising:
The modeling module 810 is used for performing geometric modeling according to the scanning data of the skeleton of the patient to obtain a geometric model, and setting corresponding physical parameters for different material parts in the geometric model to obtain an original model;
a problem correcting module 820, configured to apply a preset boundary condition and a load representing the physiological mechanics of the patient's bone to the original model, and perform simulation analysis to obtain boundary displacement data of the original model;
an inverse problem module 830, configured to receive a setting operation of an operator, set the different material portions in the geometric model as at least one isotropic material according to the setting operation, and perform inversion calculation according to the preset boundary condition, the load, and the boundary displacement data to obtain physical parameters of the isotropic material;
and the assigning module 840 is used for assigning the physical parameters of the isotropic material to the geometric model to obtain a bone model capable of representing the physiological and mechanical characteristics of the original model.
As shown in FIG. 9, in one embodiment, there is provided a system for optimized design of a bone medical device, the system comprising:
a design domain module 910, configured to determine a size of the bone medical instrument according to a position of the patient where the bone medical instrument is to be implanted, use the size of the bone medical instrument as a size of a design domain, and establish a design domain finite element model according to the size of the design domain;
An assembling module 920, configured to assemble the design domain finite element model to a target bone model to obtain a design domain implantation model, where the target bone model is a finite element model established according to actual scanning data of the bone part of the patient to be treated;
a setting module 930, configured to determine a topology optimization method, and receive constraint conditions, objective functions, boundary conditions, loads, and design variables set by an operator under an optimization framework of the topology optimization method, where the design variables are cell densities, structural boundaries, or structural parameters of a movable deformable component;
and a topology optimization module 940 for solving an optimization problem established according to the constraint condition, the objective function, the boundary condition, the load, the design variable and the design domain implantation model to obtain an optimal topology structure of the bone medical instrument.
As shown in fig. 10, in one embodiment, there is provided an intervertebral cage manufacturing system comprising an input device 1010, a display device 1020, a processor device 1030, and a manufacturing device 1040, wherein the input device 1010, the display device 1020, and the manufacturing device 1040 are respectively connected with the processor device 1030; the system comprises:
The input device 1010 is used for inputting the patient vertebra scanning data into the processor device 1030, and the processor device 1030 is used for modeling and simplifying according to the patient vertebra scanning data to obtain a vertebra finite element simplified model;
the input device 1010 is further configured to input the patient's vertebra pathophysiological parameters and a treatment plan to the processor device 1030, the processor device 1030 is further configured to build an intervertebral cage design domain finite element model according to the pathophysiological parameters and the treatment plan;
the processor device 1030 is further configured to establish an optimization problem and solve the optimization problem by using a preset topological optimization method according to the physiological and pathological parameters, the finite element model of the designed domain of the interbody fusion cage and the finite element simplified model of the vertebra to obtain an optimal topological structure;
the processor device 1030 is further configured to establish a finite element model of the interbody fusion cage according to the optimal topology, and transmit the finite element model of the interbody fusion cage to the display device 1020 for displaying, so that a clinician confirms the usability of the finite element model of the interbody fusion cage;
the processor device 1030 is further configured to issue manufacturing instructions to the manufacturing device 1040 after receiving a message from the clinician confirming that the finite element model of the interbody cage is available, the manufacturing instructions including the finite element model of the interbody cage;
The manufacturing device 1040 is further configured to manufacture the interbody cage based on the interbody cage finite element model after receiving the manufacturing instructions.
In one embodiment, the processor device 1030 is configured to model and simplify from the patient vertebrae scan data to obtain a vertebrae finite element simplified model, including: the processor device 1030 is further configured to perform geometric modeling according to the scan data of the patient's bone to obtain a geometric model, and set corresponding physical parameters for different material parts in the geometric model to obtain an original model; the processor device 1030 is further configured to apply preset boundary conditions and loads representing the physiological mechanics of the patient's bones to the original model, and perform simulation analysis to obtain boundary displacement data of the original model; the processor device 1030 is further configured to receive a setting operation of an operator, set at least two different material portions in the geometric model as isotropic materials according to the setting operation, and perform inversion calculation according to the preset boundary condition, the load, and the boundary displacement data to obtain physical parameters of the isotropic materials; the processor device 1030 is further configured to assign physical parameters of the isotropic material to the geometric model, resulting in a finite element simplified model of the vertebra.
In one embodiment, the processor device 1030 is further configured to create an intervertebral cage design domain finite element model based on the physiopathological parameters and the treatment plan, including: the processor device 1030 is further configured to obtain, according to the position of the bone medical instrument to be implanted into the patient in the treatment plan, the size of the standard bone medical instrument implanted at the position in the general treatment plan; the processor device 1030 is further configured to compare the size of the space capable of accommodating the bone medical instrument with the size of the standard bone medical instrument to obtain a comparison result, wherein the size of the space capable of accommodating the bone medical instrument is determined according to the physiopathological parameter; the processor device 1030 is further configured to adjust the size of the standard bone medical instrument according to the comparison result, and use the adjusted size of the standard bone medical instrument as the size of the bone medical instrument, so that the size of the bone medical instrument is adapted to the physiological condition and the pathological condition of the bone to be treated of the patient; the processor device 1030 is further configured to establish a finite element model of the interbody cage design domain based on the dimensions of the interbody cage design domain using the dimensions of the bone medical instrument as the dimensions of the interbody cage design domain.
In one embodiment, the processor device 1030 is further configured to establish an optimization problem according to the physiopathological parameter, the finite element model of the designed domain of the interbody fusion cage, and the finite element simplified model of the vertebra, and solve the optimization problem by using a preset topology optimization method to obtain an optimal topology structure, including: the processor device 1030 is further configured to assemble the intervertebral cage design domain finite element model to the vertebrae finite element simplified model to obtain a design domain implant model; the processor device 1030 is further configured to receive constraints, objective functions, boundary conditions, loads and design variables set by an operator under an optimization framework of the preset topology optimization method, wherein the constraints, the objective functions, the boundary conditions, the loads and the design variables are set according to the physiopathological parameters and the preset topology optimization method; wherein the design variable is a cell density, a structural boundary, or a structural parameter of a moving deformable component; the processor device 1030 is further configured to solve an optimization problem established according to the constraint condition, the objective function, the boundary condition, the load, the design variable, and the design domain implant model to obtain an optimal topology structure of the intervertebral fusion cage.
FIG. 11 is a diagram illustrating an internal structure of a computer device in one embodiment. As shown in fig. 11, the computer device includes a processor, a memory, and a network interface connected by a system bus. Wherein the memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system and may further store a computer program, which, when executed by the processor, causes the processor to implement a bone model construction method or an optimal design method for a bone medical instrument. The internal memory may also have a computer program stored therein, which when executed by the processor, causes the processor to perform a bone model construction method or a bone medical device optimization design method. Those skilled in the art will appreciate that the architecture shown in fig. 11 is merely a block diagram of some of the structures associated with the disclosed aspects and is not intended to limit the computing devices to which the disclosed aspects apply, as particular computing devices may include more or less components than those shown, or may combine certain components, or have a different arrangement of components.
In an embodiment, a computer device is proposed, comprising a memory and a processor, the memory storing a computer program which, when executed by the processor, causes the processor to perform the steps of the above-described bone model construction method or bone medical instrument optimization design method.
In an embodiment, a computer-readable storage medium is proposed, in which a computer program is stored, which computer program is executed by a processor for performing the steps of the above-mentioned bone model construction method or bone medical instrument optimization design method.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a non-volatile computer-readable storage medium, and can include the processes of the embodiments of the methods described above when the program is executed. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A method of constructing a bone model, the method comprising:
performing geometric modeling according to the scanning data of the skeleton of the patient to obtain a geometric model, and setting corresponding physical parameters for different material parts in the geometric model to obtain an original model;
applying preset boundary conditions and loads representing the physiological mechanics of the patient skeleton to the original model, and performing simulation analysis to obtain boundary displacement data of the original model;
Receiving the setting operation of an operator, setting the different material parts in the geometric model as at least one isotropic material according to the setting operation, and performing inversion calculation according to the preset boundary condition, the load and the boundary displacement data to obtain physical parameters of the isotropic material;
and assigning physical parameters of the isotropic material to the geometric model to obtain a skeleton model capable of representing the physiological and mechanical characteristics of the original model.
2. A bone model construction method according to claim 1, characterized in that the physical parameters of the isotropic material comprise two of shear modulus, elastic modulus and poisson's ratio.
3. A bone model construction method according to claim 1, wherein said applying of preset boundary conditions and loads characterizing the biomechanics of the patient's bone to said original model comprises:
applying preset constraint on the degree of freedom of a lower surface node of the lower skeleton in the original model to serve as boundary conditions;
receiving a reference point selected by said operator above an upper bone of said original model;
and applying the load to the reference point, wherein the load comprises an axial compression force and bending moments in different directions so as to simulate the working conditions of axial compression, forward bending, backward extension, lateral bending and torsional movement of the bone of the patient.
4. A method of constructing a bone model according to claim 1, wherein said setting said different material portions in said geometric model as at least one isotropic material according to said setting operation, further comprises:
setting a poisson's ratio for each of the isotropic materials.
5. The method of constructing a bone model according to claim 4, wherein said performing an inversion calculation based on said predetermined boundary conditions, said load and said boundary displacement data to obtain physical parameters of said isotropic material comprises:
taking the geometric model with the set isotropic material as an object model for inversion calculation, and acquiring three-dimensional coordinates of each node of the object model and a connection relation between the nodes;
writing the preset boundary condition, the load, the boundary displacement data, the three-dimensional coordinates of the nodes and the connection relation among the nodes into a format file for inversion calculation;
taking the format file as an input file, taking the sum of a boundary displacement data related item and a regularization data related item as a target function, taking the target function smaller than a preset threshold value as a convergence condition, and performing inversion calculation according to the input file and a preset condition of an inversion calculation program;
And when the objective function meets the convergence condition, obtaining the shear modulus of the isotropic material.
6. A bone model construction method according to claim 5, characterized in that the preset conditions of the inversion calculation procedure include:
setting the problem of inversion calculation as an incompressible plane problem;
setting a regularization constant of the objective function, an initial value of an objective function variable, upper and lower parameter limits and the maximum iteration step number of the objective function.
7. A bone model construction method according to claim 5, wherein said assigning physical parameters of said isotropic material to said geometric model, resulting in a bone model capable of characterizing the biomechanical characteristics of said original model, comprises:
calculating to obtain an elastic modulus according to the shear modulus and the Poisson ratio of the isotropic material;
and giving the elastic modulus and the shear modulus to a material part set as the isotropic material in the geometric model to obtain the bone model.
8. A bone model construction apparatus, characterized in that the apparatus comprises:
the modeling module is used for carrying out geometric modeling according to the scanning data of the skeleton of the patient to obtain a geometric model, and setting corresponding physical parameters for different material parts in the geometric model to obtain an original model;
The problem correcting module is used for applying preset boundary conditions and loads representing the physiological mechanics of the skeleton of the patient to the original model, and performing simulation analysis to obtain boundary displacement data of the original model;
the inverse problem module is used for receiving the setting operation of an operator, setting the different material parts in the geometric model as at least one isotropic material according to the setting operation, and performing inversion calculation according to the preset boundary condition, the load and the boundary displacement data to obtain the physical parameters of the isotropic material;
and the assignment module is used for assigning the physical parameters of the isotropic material to the geometric model to obtain a bone model capable of representing the physiological and mechanical characteristics of the original model.
9. A computer-readable storage medium, storing a computer program which, when executed by a processor, causes the processor to carry out the steps of the method according to any one of claims 1 to 7.
10. A computer device comprising a memory and a processor, the memory storing a computer program that, when executed by the processor, causes the processor to perform the steps of the method according to any one of claims 1 to 7.
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