CN106227993B - A kind of union dynamic process simulation method based on Biological Mechanism - Google Patents

Abstract

A method for simulating the dynamic process of fracture healing based on a biological mechanism. The invention relates to a method for simulating the dynamic process of fracture healing based on a biological mechanism. The purpose of the present invention is to solve the disadvantage that the existing fracture healing dynamic process model cannot comprehensively simulate the complex relationship among the dynamic change of callus shape, mechanical environment change and biological environment change in the fracture healing process. 1. Establishment of a three-dimensional geometric model; 2. Carry out grid division; 3. Establish a biomechanical model of bone and callus; 4. Determine the initial parameters of the simulation and apply loads and boundary conditions; For abnormal blood supply unit, if it is a normal blood supply area, then execute 6, if it is an abnormal blood supply area, then execute 7; 6. Establish a deterministic mathematical model for a normal blood supply area; 7. Establish fuzzy mathematics for an abnormal blood supply area Model; 8. Establish the simulation process of fracture healing according to 6 and 7. The invention is used in the field of biomedical engineering.

Description

A simulation method for the dynamic process of fracture healing based on biological mechanism

technical field

The invention relates to a method for simulating the dynamic process of fracture healing based on biological mechanism.

Background technique

In fact, not all fractures can be repaired, sometimes there will be non-repair or delayed repair, delayed union or non-union of fractures will cause pain in the affected limb, dysfunction, and cause unemployment for patients. Due to the large number of fracture accidents per year, fractures The number of people with delayed or non-healing is considerable, and the resulting socioeconomic burden will be substantial. Fracture delayed union or nonunion is affected by specific geometric factors, mechanical factors, and biological factors. Therefore, the research on the fracture healing process and its influence on the speed and quality of fracture healing has been receiving much attention, and some achievements have been made. However, due to the limitations of research methods and the complexity of the fracture process, which cannot be directly observed, although the research in this field has been improving, there are still about 5% to 10% of fractures with delayed union or nonunion due to various reasons.

At present, there is a lack of computer simulation models that can accurately express the complex process of fracture healing. First of all, the deterministic relationship between mechanical factors and fracture process has not been established; the mechanical environment and biological environment are not fully considered in the same simulation model. Double impact; did not solve the simulation modeling problem from the perspective of establishing an individualized model for specific patients, the geometric model and biomechanical material settings were too simplified, which affected the simulation results of the model; did not comprehensively consider the dynamic changes in the shape of the callus during the fracture healing process, The dynamic simulation of the complex relationship between the mechanical environment change and the biological environment change in the computer.

Contents of the invention

The purpose of the present invention is to solve the shortcoming that the existing fracture healing dynamic process model cannot comprehensively simulate the complex relationship between the dynamic change of the callus shape, the mechanical environment change and the biological environment change in the fracture healing process, and propose a biological The dynamic process simulation method of fracture healing based on the scientific mechanism.

A method for simulating the dynamic process of fracture healing based on biological mechanisms is implemented in the following steps:

Step 1, the establishment of three-dimensional geometric model;

Step 2, importing the obtained three-dimensional geometric model into meshing software for meshing;

Step 3, establishing a biomechanical model of bone and callus on the basis of grid division;

Step 4, on the basis of the biomechanical model of bone and callus, determine the initial parameters of the simulation and apply the load and boundary conditions;

Step 5. Carry out the simulation design of the dynamic change of callus shape on the basis of step 4. For the reserved units, divide them into normal blood supply units and abnormal blood supply units according to blood supply parameter values;

A blood supply parameter value of 100% is a normal blood supply area, and a blood supply parameter value less than 100% is an abnormal blood supply area. If it is a normal blood supply area, perform step 6, and if it is an abnormal blood supply area, perform step 7;

Step 6. Establish a deterministic mathematical model of bone density and cartilage density over time in different initial bone internal stress environments in normal blood supply areas;

Step 7, establishing the fuzzy mathematical model of the abnormal blood supply area, the fuzzy mathematical model of the abnormal blood supply area includes membership degree and fuzzy control rules;

Step 8: Establish a fracture healing simulation process according to Steps 6 and 7.

The beneficial effects of the present invention are:

The research goal of the present invention is to realize the modeling and simulation of the dynamic process of fracture healing based on the biological mechanism, and the simulation system has complexity, dynamic characteristics, individual characteristics and reliability. By establishing the definite mathematical relationship between the initial fracture internal mechanical parameters and the stiffness value of the fracture healing process, a simulation model that can reflect the influencing factors of the mechanical environment is realized; The fuzzy criterion of the relationship realizes the simulation model that can reflect the influence of the biological environment; the dynamic mechanical calculation is realized by the finite element method, the dynamic update of the bone healing process in the abnormal blood supply area is realized by the fuzzy logic controller, and the calculation of the stress distribution and the critical The choice of stress enables dynamic updating of the callus shape.

Use of the invention:

(1) By building a computer simulation system for the dynamic process of fracture healing, the system can be used as a simulation test platform for the evaluation and optimal design of various internal fixation devices that meet the biomechanical requirements of the human body; Test and analysis of the impact of healing speed and quality; conduct research to find effective ways to avoid fractures; due to the scalability of the simulation model, this platform can also analyze and study some biological factors that affect the bone healing process.

(2) By constructing a computer simulation system for the dynamic process of fracture healing, the prediction of the complex fracture healing process can be realized, which can provide guidance for doctors to formulate correct surgical plans, thereby improving the success rate of surgery, improving the quality of fracture healing, and effectively reducing fracture nonunion and To help fracture healers return to a healthy life through effective treatment and reduce the resulting social and economic burden.

(3) The simulation model established in the computer can be used to carry out repeated experimental research, without the need for real biological experiments, saving time, improving efficiency, saving costs, and avoiding humanitarian disputes.

Features of the invention:

(1) Traditional studies on the influence of mechanical environment on fracture healing process mainly focus on testing the influence of different mechanical environments on fracture healing speed and final callus stiffness through mechanical tests, most of which are qualitative studies, not from a quantitative perspective To explore this problem with the purpose of obtaining a definite mathematical model, the present invention establishes a deterministic mathematical model of fracture internal stress and fracture stiffness based on the idea of biomathematics.

(2) The influence of blood supply status is rarely considered in traditional bone healing process simulation models, and there is no research on adding blood supply reconstruction parameters as dynamic variables to the simulation model. In areas with poor blood supply environment, callus formation will The instability of the mechanical environment will limit the regeneration of blood vessels. The bone healing process is a complex process affected by various factors such as the mechanical environment and the biological environment. The present invention describes the complex process of fracture healing through fuzzy control rules. Revascularization was incorporated into the simulation model as a dynamic variable.

(3) The research work of traditional fracture healing simulation is kept at a static or research level that only embodies less dynamic variables. The present invention, by introducing the concept of critical stress, links the stress characteristics with the biological characteristics of callus formation. The deterministic mathematical model of internal stress and fracture stiffness and the fuzzy control rules of blood supply reconstruction can finally realize the computer simulation of dynamic bone healing process that can simultaneously express the change of callus shape, the change of callus material properties and the process of blood supply reconstruction.

By comparing the simulation results with the experimental data, it can be concluded that the fracture healing dynamic process simulation system based on biological mechanisms can continuously update the changes of various parameters in the fracture healing process through effective calculations, and accurately simulate fracture healing.

Description of drawings

Figure 1a is a schematic diagram of the expansion strain membership function;

Figure 1b is a schematic diagram of the distortion strain membership function;

Figure 1c is a schematic diagram of the degree of membership function of blood, cartilage, and bone density;

Figure 1d is a schematic diagram of the membership function of adjacent units;

Fig. 1e is a schematic diagram of membership degree function of blood change amount;

Figure 1f is a schematic diagram of the membership function of cartilage density;

Figure 1g is a schematic diagram of the bone density membership function;

Fig. 2 is the simulation roadmap of fracture healing dynamic process of the present invention;

Fig. 3a is a diagram of the tissue transformation process of the present invention;

Figure 3b is a diagram of the process of vascular tissue transformation in the present invention;

Fig. 4 is the schematic diagram of applied load and boundary conditions of the present invention;

Fig. 5a shows the schematic diagram of the simulation results and experimental data of the inter-fracture displacement (i.e. interosseous mobility)) of the 2mm stable group as a function of time;

Fig. 5b is a schematic diagram of the simulation results and experimental data of the inter-fracture displacement (that is, the interosseous motion)) of the 3 mm unstable group as a function of time.

detailed description

Embodiment 1: A method for simulating the dynamic process of fracture healing based on biological mechanisms in this embodiment is specifically carried out in accordance with the following steps:

Step 1, the establishment of three-dimensional geometric model;

Step 2, importing the obtained three-dimensional geometric model into meshing software for meshing;

Step 3, establishing a biomechanical model of bone and callus on the basis of grid division;

Step 4, on the basis of the biomechanical model of bone and callus, determine the initial parameters of the simulation and apply the load and boundary conditions;

Step five, on the basis of step four, carry out the simulation design of the dynamic change of callus shape;

Step 6. Establish a deterministic mathematical model of bone density and cartilage density over time in different initial bone internal stress environments in normal blood supply areas;

Step 7, establishing the fuzzy mathematical model of the abnormal blood supply area, the fuzzy mathematical model of the abnormal blood supply area includes membership degree and fuzzy control rules;

Step 8: Establish a fracture healing simulation process according to Steps 6 and 7.

Specific embodiment two: the difference between this embodiment and specific embodiment one is: the establishment of the three-dimensional geometric model in the step one; the specific process is:

Using the segmentation-based 3D medical image surface reconstruction algorithm to reconstruct the 3D surface of the image to obtain a 3D geometric model;

The image is obtained by imaging equipment CT, and the data storage format is DICOM.

The process of constructing the solid model from the surface model is to construct the surface list of the solid model from the triangular slice sequence of the surface model and the upper and lower bottom surfaces, and construct the vertex list of the solid model from the vertex sequence of the surface model, and simultaneously establish the body, ring, edge and half edge The linked list and the pointing relationship of the nodes in each linked list. The solid construction process expressed by the boundary model is realized by a series of Euler operations. The basic Euler operations include the following 5 pairs of reciprocal inverses: MVFS, MEV, MEF, MEKR, KFMRH; KVFS, KEV, KEF, KEMR, MFKRH. Among them, M represents structure, K represents deletion, and S, E, V, F, R, H represent body, edge, vertex, face, ring and hole respectively.

Other steps and parameters are the same as those in Embodiment 1.

Specific embodiment three: the difference between this embodiment and specific embodiment one or two is: the three-dimensional geometric model obtained in the described step 2 is imported into the grid division software to carry out grid division; the specific process is:

Because the grid division software will generate a lot of data, the present invention only needs node coordinates and unit numbers, imports the obtained 3D geometric model into MATLAB for preprocessing, only extracts the target data, and generates the required data for subsequent finite element calculations based on the target data. Two files of unit number and node coordinates;

The two files of the unit number and node coordinates are files in txt text format;

The node coordinate file contains three columns of data, and the three columns of data represent the spatial coordinate values of each node;

The unit number file contains four columns of data, which are the node serial numbers of the four nodes of each unit.

Other steps and parameters are the same as those in Embodiment 1 or Embodiment 2.

Specific embodiment four: this embodiment is different from one of specific embodiments one to three: in the step 3, the biomechanical model of bone and callus is established on the basis of grid division; the specific process is:

Aiming at the mechanical properties of bone and callus, the constitutive equations of linear elastic materials and nonlinear materials are established by using the method of continuum mechanics, and the mechanical properties of biological tissues are described by the potential energy function of bone and callus by Green's method;

Bone is a linear elastic material, and the elastic potential energy W(X) is a quadratic function of the infinitesimal strain tensor:

In the formula, λ, μ are Lame constants, E _L is the linear strain tensor;

The formula for calculating the unit stress of a linear elastic material is:

{ε}=[S]·{σ},

In the formula, {σ} is the element stress of linear elastic material, {ε} is the strain of linear elastic material, and [S] is the flexibility matrix;

In the formula, E ₁₂ and E ₃ are the modulus of elasticity, ν ₁₃ and ν ₁₂ are Poisson's ratios, μ ₁₃ is the shear modulus, which is a material engineering constant, and 1, 2, and 3 represent the radial and tangential directions of the bone, respectively. and axial;

The callus is a nonlinear elastic material, and the elastic potential energy W is expressed as:

In the formula: I ₁ and I ₂ are the first and second principal invariants of strain tensor respectively, β and C ₁ are material constants respectively;

The calculation formula of nonlinear elastic material element stress is:

dσ = D _T dε,

In the formula, dσ is the element stress of the nonlinear elastic material, dε is the element strain of the nonlinear elastic material, and D _T is the tangent elastic matrix;

The tangent elasticity matrix D _T is:

where E is the Green strain tensor.

Other steps and parameters are the same as those in Embodiments 1 to 3.

Embodiment 5: This embodiment is different from Embodiment 1 to Embodiment 4 in that: in the step 4, on the basis of the biomechanical model of bone and callus, the initial parameters of the simulation and the applied load and boundary conditions are determined; the specific process for:

Set the initial blood supply parameters and initial tissue characteristic parameters of each unit according to the actual fracture status of the patient, and add loads and boundary conditions according to the determined fracture fixation method;

There are two ways to add loads and boundary conditions, one is to apply displacement, and the other is to apply force.

If the material is rigid or the boundary material is harder than the material we are studying, such a contact collision can be simulated by applying a given displacement at a series of vertices; Spring force to model.

Other steps and parameters are the same as in one of the specific embodiments 1 to 4.

Embodiment 6: The difference between this embodiment and one of Embodiments 1 to 5 is that in the step 5, the simulation design of the dynamic change of the callus shape is carried out on the basis of the step 4, and for the retained units, according to the blood supply parameters The value is divided into normal blood supply unit and abnormal blood supply unit; blood supply parameter value 100% is a normal blood supply area, blood supply parameter value less than 100% is an abnormal blood supply area, if it is a normal blood supply area, go to step 6 , if it is an area with abnormal blood supply, go to step 7;; the specific process is:

By setting the critical stress value, according to the state of mechanical distribution, when the unit stress is greater than or equal to the critical stress value, the unit is the unit that needs to be retained; when the unit stress is greater than or equal to the critical stress value, the unit is the unit absorbed by the tissue;

For the retained units, they are divided into normal blood supply units and abnormal blood supply units according to the value of blood supply parameters;

A blood supply parameter value of 100% is a normal blood supply area, and a blood supply parameter value less than 100% is an abnormal blood supply area. If it is a normal blood supply area, perform step 6, and if it is an abnormal blood supply area, perform step 7;

The critical stress is calculated by multiplying the maximum third principal strain ε _3,max with a coefficient e, critical stress = eε _3,max .

The mechanical calculation of the whole simulation process is also based on the finite element idea to design the solution model; the low stress vector of granulation tissue is used to define the space distribution of the callus, and due to the existence of soft tissue, a large range of motion within the fracture can be generated, which is determined by This may produce a larger callus, and the ratio of the maximum allowable amount of compressive strain to strength was used to determine callus shape and size.

Other steps and parameters are the same as one of the specific embodiments 1 to 5.

Embodiment 7: This embodiment is different from Embodiment 1 to Embodiment 6 in that: the value of the coefficient e is between 0-1.

Other steps and parameters are the same as one of the specific embodiments 1 to 6.

Embodiment 8: The difference between this embodiment and one of Embodiments 1 to 7 is that in the step 6, the certainty of bone density and cartilage density over time in different initial bone internal stress environments is established. Mathematical model; the specific process is:

Preliminary analysis of the internal relationship between fracture internal stress and bone healing speed; in the statistical analysis, select the material data that meet the requirements, and establish the relationship curve between the healing time and the change of bone density and cartilage density; the normal blood supply area in different initial bone Under the stress environment, the deterministic mathematical model of bone density and cartilage density changing with time is:

f(t)=a(t ^m -1)+1

f'(t)=a'(t ^m' -1)+1

In the formula, a, a' are the coefficients of the blood supply area under different initial bone internal stresses; m, m' are the indices of the blood supply area under different initial bone internal stresses; f(t) is the bone density, f'( t) is cartilage density, and t is time.

Material data collation, statistics and comparative research;

The research data meeting the following conditions were selected for analysis: fractures or corresponding areas with little vascular injury (100% hyperemia); bone density, cartilage density and movement in the fracture were recorded during the test; the internal stress of the initial fracture was known or Obtained through calculation in step 3; the experimental research is continuous, and the results of at least 7 weeks have been counted; the fracture mode and location are similar. Classify and analyze the test, and classify the existing test data or newly designed test data by stress size, fixing method, measurement method, measurand, and gap;

The experimental materials generally record the displacement within 8 weeks, that is, the changes in the movement within the fracture. By establishing the relationship between the movement within the fracture and the changes in bone density and cartilage density, the test materials are unified, and the unified unit and measurement standard are determined at the same time. These are the basis for comparative analysis of data, and each group of experimental data is analyzed separately to find out the rules and characteristics.

The main steps to establish the empirical formula are: a. According to the sorted data table, select the appropriate coordinates, draw the data line or scatter diagram; b. judge the functional relationship according to the shape of the line or scatter diagram, and establish the regression equation; c. According to the regression equation, undetermined constants are obtained, and the correlation test is carried out.

Other steps and parameters are the same as one of the specific embodiments 1 to 7.

Specific embodiment nine: the difference between this embodiment and one of the specific embodiments one to eight is: the fuzzy mathematical model of the abnormal blood supply area is established in the step seven, and the fuzzy mathematical model of the abnormal blood supply area includes membership degree and fuzzy Control rules; the specific process is:

Step 71, establishing a membership function;

Using the three tissue concentration variables of hyperemia, cartilage density, and bone density, the hyperemia of adjacent units, the bone density of adjacent units, and two mechanical stimuli of expansion strain and distortion strain as fuzzy inputs, the tissue differentiation process is described through 21 fuzzy control rules ;Using the changes in hyperemia, bone density, and cartilage density as output; first establish the linguistic values of 7 input and 3 output linguistic variables, and then establish based on the results of histological experiments and cell culture experiments as shown in Figure 1a, Figure 1b, The membership functions shown in Figure 1c, Figure 1d, Figure 1e, Figure 1f, and Figure 1g;

Set the language values of 7 input and 3 output language variables, and establish the membership function;

The 7 inputs are hyperemia, cartilage density, bone density, hyperemia of adjacent units, bone density of adjacent units, expansion strain, and distortion strain;

The 3 outputs are the change of hyperemia, the change of bone density, and the change of cartilage density;

Step seventy-two, establishing fuzzy control rules;

The fuzzy control rules mainly describe the tissue transformation process in the healing process. These rules are the basis of the fuzzy model. This study uses the statement description of if A and B then C, and its main form is shown in Table 1.

Rules 1-4 are revascularization, specifically called:

The stimulation of the hematoma regenerates capillaries at the fracture site. Capillary regeneration is the process of generating new blood vessels from existing blood vessels, and produces biological effects under the control of mechanics to induce vascular reconstruction;

Rules 5 and 6 are intramembranous ossification, specifically called:

Intramembranous ossification is an osteogenic way of bone growth, especially when there is no cartilage formation during osteogenesis, intramembranous ossification is a direct transformation form of connective tissue into bone tissue; in the early stage, bone marrow mesenchymal stem cells begin to Proliferation gathers, angiogenesis activity increases, and capillaries begin to grow; bone marrow mesenchymal stem cells develop into osteoblasts and begin to produce osteoid; at the same time, osteoid begins to mineralize at the same rate; Osteocytes promote the formation of new osteoid; osteoblasts gradually become bone cells. This type of osteogenesis occurs only under the conditions of stable mechanical environment and sufficient blood supply, and the adjacent units have high bone density.

Rules 7-9 are for the formation of cartilage, specifically called:

In the case of poor fixation, greater movement of the broken end of the fracture, and insufficient blood supply, the mesenchymal cells in the tissue around the broken end will differentiate into chondrocytes, and then produce cartilage.

Rules 10-13 are the cartilage calcification process, specifically called:

After cartilage callus is formed, osteoblasts synthesize and secrete collagen, proteoglycan and glycoprotein under high stress stimulation to form the organic matter of bone;

Collagen solution gradually aggregates into collagen fibers, and is surrounded by matrix together with osteoblasts, and calcification occurs gradually; this process occurs independently of blood supply.

Rules 14 and 15 are the cartilage ossification process, which is specifically called:

In the calcified area of cartilage, the gradual diffusion of nutrients is hindered, the chondrocytes are gradually apoptotic, the calcified matrix is gradually degraded, and angiogenesis factors are released. At this time, a large number of capillaries and osteoblasts invade, and the mineralized cartilage matrix gradually produces a Ossification occurs in bone; therefore, fully calcified cartilage can undergo ossification only under the condition of good blood supply; in this model, fully calcified cartilage is expressed with high bone density and low cartilage density. The rules predicted not only an increase in bone density but also a decrease in cartilage density by the same amount.

In addition to the callus differentiation process under normal conditions, rules 16-21 are bone tissue atrophy or The blood supply, bone density and cartilage density remain unchanged when the conditions for inducing bone tissue differentiation are not produced;

The organizational transformation process mainly described by fuzzy rules is shown in Figure 2;

Other steps and parameters are the same as those in Embodiments 1 to 8.

Embodiment 10: The difference between this embodiment and one of Embodiments 1 to 9 is that in Step 8, the simulation process of fracture healing is established according to Step 6 and Step 7; the specific process is called:

After the finite element model is established, solve the finite element model to obtain the unit stress. When the unit stress is greater than or equal to the critical stress value, the unit is the unit that needs to be retained. When the unit stress is greater than or equal to the critical stress value, the unit is the unit absorbed by the tissue;

For the retained units, they are divided into normal blood supply units and abnormal blood supply units according to the value of blood supply parameters;

A blood supply parameter value of 100% is a normal blood supply area, and a blood supply parameter value of less than 100% is an abnormal blood supply area;

If it is a normal blood supply unit, update its state through a deterministic mathematical model of bone density and cartilage density in the normal blood supply area over time;

If it is an abnormal blood supply unit, the change of blood supply information and the update of bone tissue characteristics are determined through the fuzzy mathematical model;

After completion, repeat steps 1 to 8; until the last callus is generated, there are no more absorbable units; (by deleting the edges and redundant nodes of the corresponding grid units); the specific implementation steps are shown in Figure 3a and Figure 3b :

The finite element model includes a three-dimensional geometric model, grid division, biomechanical model, load and boundary conditions, and initial simulation parameters.

Adopt the following examples to verify the beneficial effects of the present invention:

Embodiment one:

In this embodiment, a method for simulating the dynamic process of fracture healing based on biological mechanisms is specifically prepared according to the following steps:

To simulate the healing of metatarsal fractures in sheep, a load of F=500N is applied to the top of the model, assuming that this is enough to meet the maximum force that the metatarsals may bear during normal walking of sheep. The bottom part is a fixed constraint part, and its degrees of freedom are all 0, including displacement in three directions and rotation in three directions. The placement of the external fixture makes the model only have axial displacement, and the degrees of freedom in other directions are all zero. Fig. 4 is a schematic diagram of the applied load and fixation constraints of the three-dimensional external fixation transverse osteotomy model. The elastic modulus of bone is 4000, and Poisson's ratio is 0.36. The elastic modulus of cartilage is 200, and Poisson's ratio is 0.45. Table 2 shows the selection of initial blood supply parameters and material performance parameters; Figure 5a and Figure 5b are 2mm gaps respectively Simulation results for the stable case and the unstable case with a 3mm gap.

Table 2 Selection of initial blood supply parameters and material performance parameters

The present invention can also have other various embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations are all Should belong to the scope of protection of the appended claims of the present invention.

Claims (10)

1. a kind of union dynamic process simulation method based on Biological Mechanism, it is characterised in that：One kind is based on biology The union dynamic process simulation method of mechanism is specifically what is followed the steps below：

Step 1: the foundation of 3-D geometric model；

Step 2: obtained 3-D geometric model to be imported into mesh generation software to the division for carrying out grid；

Step 3: setting up bone and the biomechanical model of poroma on the basis of the division of grid；

Step 4: on the basis of bone and the biomechanical model of poroma, it is determined that emulation initial parameter and application load and perimeter strip Part；

Step 5: the design of Simulation of poroma shape dynamic change is carried out on the basis of step 4, for the unit of reservation, foundation Blood supply parameter value divides into normal blood supply unit and improper blood supply unit；

Blood supply parameter value 100% is normal blood supply region, and it is improper blood supply region that blood supply parameter value, which is less than 100%, if Normal blood supply region then performs step 6, if improper blood supply region then performs step 7；

Step 6: setting up normal blood supply region under different initial internal stress of bone environment, bone density, cartilage density are changed over time Deterministic mathematical model；

Step 7: setting up the fuzzy mathematical model in improper blood supply region, the fuzzy mathematical model in improper blood supply region includes Degree of membership and fuzzy control rule；

Step 8: setting up the simulation process of union according to step 6 and step 7.

2. a kind of union dynamic process simulation method based on Biological Mechanism according to claim 1, its feature exists In：The foundation of 3-D geometric model in the step one；Detailed process is：

Three-dimensional surface reconstruct is carried out to image using the 3 d medical images resurfacing algorithm based on segmentation, three-dimensional geometry is obtained Model；

Described image is obtained by image documentation equipment CT, and data memory format is DICOM.

3. a kind of union dynamic process simulation method based on Biological Mechanism according to claim 2, its feature exists In：Obtained 3-D geometric model is imported into mesh generation software to the division for carrying out grid in the step 2；Specific mistake Cheng Wei：

Obtained 3-D geometric model is imported into MATLAB and pre-processed, target data is only extracted, according to target data Generate two files of element number and node coordinate required for follow-up FEM calculation；

Described two files of element number and node coordinate are the file of txt text formattings；

Node coordinate file includes three column datas, and three column datas represent the spatial value of each node respectively；

Element number file includes four column datas, and four column datas are respectively the node ID of four nodes of each unit.

4. a kind of union dynamic process simulation method based on Biological Mechanism according to claim 3, its feature exists In：Bone and the biomechanical model of poroma are set up in the step 3 on the basis of the division of grid；Detailed process is：

The constitutive equation of linear elastic materials, nonlinear material is set up using continuum mechanics theory, using green method, is passed through Bone and the potential-energy function of poroma carry out describing mechanical；

Bone is linear elastic materials, and elastic potential energy W (X) is the quadratic function of infinitesimal strain tensor：

<mrow> <mi>W</mi> <mrow> <mo>(</mo> <mi>X</mi> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <mi>&amp;lambda;</mi> <mn>2</mn> </mfrac> <msup> <mrow> <mo>(</mo> <msub> <mi>trE</mi> <mi>L</mi> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>+</mo> <msubsup> <mi>&amp;mu;trE</mi> <mi>L</mi> <mn>2</mn> </msubsup> </mrow>

In formula, λ, μ is Lame (Lame) constant, E_LFor linear strain tensor；

Linear elastic materials element stress calculation formula is：

{ ε }=[S] { σ },

In formula, { σ } is linear elastic materials element stress, and { ε } strains for linear elastic materials unit, and [S] is flexibility matrix；

<mrow> <mo>&amp;lsqb;</mo> <mi>S</mi> <mo>&amp;rsqb;</mo> <mo>=</mo> <mfenced open = "[" close = "]"> <mtable> <mtr> <mtd> <mfrac> <mn>1</mn> <msub> <mi>E</mi> <mn>12</mn> </msub> </mfrac> </mtd> <mtd> <mrow> <mo>-</mo> <mfrac> <msub> <mi>v</mi> <mn>12</mn> </msub> <msub> <mi>E</mi> <mn>12</mn> </msub> </mfrac> </mrow> </mtd> <mtd> <mrow> <mo>-</mo> <mfrac> <msub> <mi>v</mi> <mn>31</mn> </msub> <msub> <mi>E</mi> <mn>3</mn> </msub> </mfrac> </mrow> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mrow></mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mo>-</mo> <mfrac> <msub> <mi>v</mi> <mn>12</mn> </msub> <msub> <mi>E</mi> <mn>12</mn> </msub> </mfrac> </mrow> </mtd> <mtd> <mfrac> <mn>1</mn> <msub> <mi>E</mi> <mn>12</mn> </msub> </mfrac> </mtd> <mtd> <mrow> <mo>-</mo> <mfrac> <msub> <mi>v</mi> <mn>31</mn> </msub> <msub> <mi>E</mi> <mn>3</mn> </msub> </mfrac> </mrow> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mn>0</mn> </mtd> <mtd> <mrow></mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mo>-</mo> <mfrac> <msub> <mi>v</mi> <mn>13</mn> </msub> <msub> <mi>E</mi> <mn>12</mn> </msub> </mfrac> </mrow> </mtd> <mtd> <mrow> <mo>-</mo> <mfrac> <msub> <mi>v</mi> <mn>13</mn> </msub> <msub> <mi>E</mi> <mn>12</mn> </msub> </mfrac> </mrow> </mtd> <mtd> <mfrac> <mn>1</mn> <msub> <mi>E</mi> <mn>3</mn> </msub> </mfrac> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mrow></mrow> </mtd> </mtr> <mtr> <mtd> <mrow></mrow> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mfrac> <mn>1</mn> <msub> <mi>&amp;mu;</mi> <mn>12</mn> </msub> </mfrac> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mrow></mrow> </mtd> </mtr> <mtr> <mtd> <mrow></mrow> </mtd> <mtd> <mn>0</mn> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mfrac> <mn>1</mn> <msub> <mi>&amp;mu;</mi> <mn>13</mn> </msub> </mfrac> </mtd> <mtd> <mrow></mrow> </mtd> </mtr> <mtr> <mtd> <mrow></mrow> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mrow></mrow> </mtd> <mtd> <mfrac> <mn>1</mn> <msub> <mi>&amp;mu;</mi> <mn>13</mn> </msub> </mfrac> </mtd> </mtr> </mtable> </mfenced> </mrow>

In formula, E₁₂For the modulus of elasticity for radially and tangentially forming plane of bone, E₃For the axial modulus of elasticity of bone, ν₁₃For The Poisson's ratio of the radial and axial formation plane of bone, ν₁₂For the Poisson's ratio for radially and tangentially forming plane of bone, ν₃₁For bone The Poisson's ratio for axially and radially forming plane of bone, μ₁₃For the modulus of shearing of the radial and axial formation plane of bone, μ₁₂For bone The modulus of shearing for radially and tangentially forming plane of bone, E₁₂、E₃、ν₁₃、ν₁₂、ν₃₁、μ₁₃、μ₁₂For material engineering constant, 1,2,3 point The radial direction of bone, tangential and axial direction are not represented；

Poroma is nonlinear elastic material, and elastic potential energy W is expressed as：

<mrow> <mi>W</mi> <mo>=</mo> <msub> <mi>C</mi> <mn>1</mn> </msub> <msup> <mi>e</mi> <mrow> <mi>&amp;beta;</mi> <mrow> <mo>(</mo> <msub> <mi>I</mi> <mn>1</mn> </msub> <mo>-</mo> <mn>3</mn> <mo>)</mo> </mrow> </mrow> </msup> <mo>-</mo> <mfrac> <mrow> <msub> <mi>C</mi> <mn>1</mn> </msub> <mi>&amp;beta;</mi> </mrow> <mn>2</mn> </mfrac> <mrow> <mo>(</mo> <msub> <mi>I</mi> <mn>2</mn> </msub> <mo>-</mo> <mn>3</mn> <mo>)</mo> </mrow> </mrow>

In formula：I₁、I₂It is first, second main invariant of strain tensor, β, C respectively₁It is material constant respectively；

Nonlinear elastic material element stress calculation formula is：

D σ=D_TD ε,

In formula, d σ are nonlinear elastic material element stress, and d ε strain for nonlinear elastic material unit, D_TFor tangential elasticity square Battle array；

Tangential elasticity matrix D_TFor：

<mrow> <msub> <mi>D</mi> <mi>T</mi> </msub> <mo>=</mo> <mfrac> <mrow> <msup> <mo>&amp;part;</mo> <mn>2</mn> </msup> <mi>W</mi> </mrow> <mrow> <mo>&amp;part;</mo> <msup> <mi>E</mi> <mn>2</mn> </msup> </mrow> </mfrac> </mrow>

In formula, E is Green strain tensor.

5. a kind of union dynamic process simulation method based on Biological Mechanism according to claim 4, its feature exists In：In the step 4 on the basis of bone and the biomechanical model of poroma, it is determined that emulation initial parameter and application load and side Boundary's condition；Detailed process is：

The initial blood supply parameter of each unit, initial structure characterisitic parameter are set according to the actual fracture condition of patient, according to the bone of determination Roll over fixed form, addition load and boundary condition；

The method that addition load and boundary condition have two kinds of applications, one is to apply displacement, and two be applying power.

6. a kind of union dynamic process simulation method based on Biological Mechanism according to claim 5, its feature exists In：The design of Simulation of poroma shape dynamic change is carried out in the step 5 on the basis of step 4, for the unit of reservation, Normal blood supply unit and improper blood supply unit are divided into according to blood supply parameter value；Blood supply parameter value 100% is normal blood supply area Domain, it is improper blood supply region that blood supply parameter value, which is less than 100%, if normal blood supply region then performs step 6, if Improper blood supply region then performs step 7；Detailed process is：

By setting critical stress value, when element stress is more than or equal to critical stress value, the unit that unit retains for needs, when When element stress is more than or equal to critical stress value, unit is the unit being absorbed by tissue；

For the unit of reservation, normal blood supply unit and improper blood supply unit are divided into according to blood supply parameter value；

Blood supply parameter value 100% is normal blood supply region, and it is improper blood supply region that blood supply parameter value, which is less than 100%, if Normal blood supply region then performs step 6, if improper blood supply region then performs step 7；

Limit stress=e ε_3,max

In formula, ε_3,maxFor maximum 3rd principal strain, e is coefficient.

7. a kind of union dynamic process simulation method based on Biological Mechanism according to claim 6, its feature exists In：The value of the coefficient e is between 0-1.

8. a kind of union dynamic process simulation method based on Biological Mechanism according to claim 7, its feature exists In：Normal blood supply region is set up in the step 6 under different initial internal stress of bone environment, bone density, cartilage density are with the time The deterministic mathematical model of change；Detailed process is：

Set up healing time and bone density, the relation curve of cartilage variable density；Then normal blood supply region is in different initial bones Under ambient stress, the deterministic mathematical model that bone density, cartilage density are changed over time is：

F (t)=a (t^m-1)+1

F ' (t)=a ' (t^m′-1)+1

In formula, a, a ' are coefficient of the blood supply region under different initial internal stress of bone；M, m ' are blood supply region in different initial bones Index under internal stress；F (t) is bone density, and f ' (t) is cartilage density, and t is the time.

9. a kind of union dynamic process simulation method based on Biological Mechanism according to claim 8, its feature exists In：The fuzzy mathematical model in improper blood supply region, the fuzzy mathematical model in improper blood supply region are set up in the step 7 Including degree of membership and fuzzy control rule；Detailed process is：

Step 7 one, set up membership function；

The Linguistic Value of 7 inputs, 3 output language variables is set, membership function is set up；

7 inputs are hyperemia, cartilage density, bone density, the hyperemia of adjacent cells, the bone density of adjacent cells, expansion strain, abnormal Become strain；

3 are output as congested knots modification, the knots modification of bone density, the knots modification of cartilage density；

Step 7 two, set up fuzzy control rule；

Regular 1-4 is reconstructing blood vessel, and detailed process is：

The stimulation of hemotoncus causes the capillary regeneration of fracture, and capillary regeneration is that new blood is produced from already present blood vessel The process of pipe, and produce biological effect and induction of vascular under the regulation and control of mechanics and rebuild；

Rule 5 and regular 6 is intermembranous ossification, and detailed process is：

Intermembranous ossification is the direct reformulationses that connective tissue changes osteogenic tissue；Initial stage, mesenchymal stem cells MSCs starts to increase Aggregation is grown, angiogenic activity increase, capillary starts to increase；Mesenchymal stem cells MSCs and then to develop into skeletonization thin Born of the same parents, start to produce osteoid；Meanwhile, osteoid starts with identical speed mineralising；In bone surface, generated newly by Gegenbaur's cell Osteoid；And Gegenbaur's cell becomes osteocyte；

Regular 7-9 is the formation of cartilage, and detailed process is：

In fracture site activity, in the case that blood supply is not enough, it is thin that the mesenchymal cell in broken ends of fractured bone tissue can be divided into cartilage Born of the same parents, then produce cartilage；

Regular 10-13 is cartilaginous calcification process, and detailed process is：

After the cartilage callus grades are formed, Gegenbaur's cell synthesizes under stress stimulation and secrets out of procollagen, proteoglycan and glycoprotein, structure The organic matter of skeletonization；

Procollagen aggregates into collagenous fibres, and is surrounded with Gegenbaur's cell by matrix, occurs calcification；

Rule 14,15 is chondral ossification process, and detailed process is：

In zone of calcifying cartilage, nutriment occur obstacle, articular chondrocyte apoptosis, calcified matrix degraded, release angiogenic growth because Son, now, capillary and Gegenbaur's cell intrusion, the cartilage matrix of mineralising produce osteoid, occur ossified phenomenon；Therefore, exist Under conditions of blood supply, the cartilage of complete calcification could ossify；

Regular 16-21 is is 4%~8%, -4%~-8% in expansion strain, under the loading environment of distortion strain 14%~20% It is constant that caused bone tissue atrophy or no generation induce blood supply, bone density, the cartilage density kept during bone tissue differentiation condition.

10. a kind of union dynamic process simulation method based on Biological Mechanism according to claim 9, its feature exists In：The simulation process of union is set up in the step 8 according to step 6 and step 7；Detailed process is：

After FEM model is established, solution to model calculation is carried out to FEM model, element stress is drawn, when element stress is big When equal to critical stress value, unit is needs the unit retained, and when element stress is more than or equal to critical stress value, unit is The unit being absorbed by tissue；

For the unit of reservation, normal blood supply unit and improper blood supply unit are divided into according to blood supply parameter value；

Blood supply parameter value 100% is normal blood supply region, and it is improper blood supply region that blood supply parameter value, which is less than 100%,；

If normal blood supply unit, qualitative mathematics really are changed over time by normal blood supply region bone density and cartilage density Its state of model modification；

If improper blood supply unit, by fuzzy mathematical model determine blood supply information change and bone tissue characteristic more Newly；

After the completion of repeat step one to step 8；There is no absorbable unit for poroma generation end to the last；

The FEM model includes 3-D geometric model, mesh generation, biomechanical model, load and boundary condition, emulation Initial parameter.