CN105678845A - 3D printing customized modeling method based on finite element analysis - Google Patents

Abstract

The invention discloses a 3D printing customized modeling method based on finite element analysis. Based on a human body 3D geographical statistical model, according to CT images, the method builds an accurate integrated model of prostheses, fixing parts and human tissues satisfying the special requirements of a patient. Through a finite element analysis method, mechanical deformation of a prosthesis inside a real human body is analyzed, so that scientific data are provided for scientific placement of the prosthesis, design of fixing part sizes, prosthesis carving and deformation under force, and evaluation, analysis and optimization of a prosthesis implanting surgery. Finally, supporting software which integrates automatic modeling and structure optimization of the prosthesis and is oriented to 3D printing is designed, and prosthesis model 3D printing is achieved. The invention provides a customized prosthesis model according with practical needs, and mechanical and availability analyses are conducted on the prosthesis model during the building process, so that the prosthesis model can be more suitable for the patient.

Description

3D based on finite element analysis prints personalized modeling method

Technical field

The invention belongs to Medical Image Processing and Virtual Reconstruction field, relate generally to a kind of personalized prosthese three-dimensional modeling method, be specifically related to a kind of 3D based on finite element analysis and print personalized modeling method.

Background technology

In 3D printing research, the most popular application is in biologic medical at present, and it is that current 3D printing technique is in one of the most successful technology of medical domain that 3D prints personalized orthopaedics implantation prosthese. In Orthopeadic Surgery, osteopathia damage state be various informative, vary, thus be accordingly used in the implant of bone defect healing also can only be individuation. And present stage China's artificial prosthesis manufacturer still produce in machining mode, the artificial prosthesis the inaccuracy that produce use every patient, the position of sound production of shortage science, stress, fixture, hollow out, deformation and Surgical Evaluation analysis, do not reach safety and precise and produce and install the artificial prosthesis being suitable for Individual Practical.

The three-dimensional modeling of medical image is to medical diagnosis on disease, Surgery Simulation, and location and the measurement of histoorgan all play important effect. By setting up the threedimensional model of human body damaged tissues, it is provided that being accurately positioned and registration data of area-of-interest, surgical simulation and surgical guidance are provided for doctor, reduce operation risk.

Finite element analysis is a kind of modern computing method developed rapidly for structure mechanics analysis, and its application on biomechanical analysis gets more and more. Along with the rise of 3D printing technique, finite element method obtains and is more widely applied. Foreign scholar, by finite element method is applied to the implant analysis of the 3D mandibular bone printed, improves the design of mandibular prostheses, thus improve the practical application effect of mandibular prostheses by finite element method.

Domestic at present still lack correlational study that 3D is printed, to the personalized three-dimensional modeling technique of damaged tissues and the prosthese mechanical analysis giving finite element method, cause obstruction to 3D printing technique in the application further of medical field.

Summary of the invention

For above-mentioned problems of the prior art, it is an object of the invention to, there is provided a kind of 3D based on finite element analysis to print personalized modeling method, it is achieved artificial prosthesis, fixture and tissue integrated modelling, the model built is analyzed and optimizes and print for 3D.

In order to realize above-mentioned task, the present invention by the following technical solutions:

A kind of 3D based on finite element analysis prints personalized modeling method, comprises the following steps:

Step one, to needing the skeleton part setting up artificial prosthesis to carry out three-dimensional reconstruction, obtains threedimensional model, this threedimensional model cuts and retains the model of part interested;

The CT data of subjects bones's defect part in the model of part interested according to the symmetry of skeleton or are fitted according to the form law of human body three-dimensional statistical model, obtain artificial prosthesis threedimensional model by step 2;

Step 3, design meets the fixture model that operation requires, and set up the tissue threedimensional model around damaged part, the tissue threedimensional model around artificial prosthesis threedimensional model, fixture model and damaged part is combined, obtains Integrated Model;

Step 4, processes the Integrated Model gridding obtained, generates FEM mesh;

Step 5, carries out contrast test, the accuracy of the integrated grid model that checking previous step is set up with normal human body, the model beyond error allowed band carries out again demonstration and design;

Step 6, applies different constraints and load simulated postoperative human body stressing conditions at different conditions to the Integrated Model after checking, and the optimizing research for model provides analytical data;

Step 7, is printed Integrated Model by 3D printing technique, obtains meeting the prosthese model of human body actual demand.

Further, the detailed process of step one includes:

Utilize MR or CT technology that human skeleton is carried out three-dimensional reconstruction, according to different CT values, CT image is carried out Threshold segmentation, on CT faultage image basis after singulation, be filtered, fill, utilize iso-surface patch or volume drawing to obtain the threedimensional model of skeleton; In the three-dimensional model, threedimensional model being cut, obtain the model of part interested after cutting, this part interested is the model comprising patient's defect.

Further, the detailed process of step 2 includes:

(1) the similar curved surface at bone damage position is found out

Situation 1: if damaged part can restore according to the symmetry of skeleton and obtain, just the direct antimere according to patient's human body determines similar curved surface;

Situation 2: if damaged part is bigger, it is impossible to restore according to skeleton symmetry, then can be obtained the similar curved surface of damaged part by the method for data base's matching; Here data base refers to the data base preserving normal human's skeleton three-dimensional data, therefrom selects to determine similar curved surface with the three-dimensional data of the damaged part place identical skeleton of skeleton;

(2) according to the similar curved surface found, cubic spline interpolation method is utilized to obtain toroidal function; Then artificial prosthesis threedimensional model is obtained.

Further, in step 2, the detailed process of (2) including:

Cubic spline interpoliation function representation is:

S_i(x)=a_i+b_i(x-x_i)+c_i(x-x_i)²+d_i(x-x_i)³

In above formula, i=0,1 ..., n-1; a_i,b_i,c_i,d_iRepresent 4n unknowm coefficient.

Similar curved surface suppose there is n+1 data point, be respectively as follows:

(x₀, y₀), (x₁, y₁), (x₂, y₂) ..., (x_n, y_n);

(2-1) material calculation h_i=x_i+1-x_i(i=0,1 ..., n-1), carry it into curvilinear function S_iIn (x);

(2-2) coefficient of cubic spline curve is calculated:

Have according to difference and seriality:

S_i(x_i)=y_i(i=0,1 ..., n-1)

Obtain:

a_i=y_i

According to S_i(x_i+1)=y_i+1(i=0,1 ..., n-1)

a_i+h_ib_i+h_i ²c_i+h_i ³d_i=y_i+1

Have according to differential seriality:

(x_i+1)=S_i+1′(x_i+1) (i=0,1 ..., n-1)

Then can release:

S_i′(x_i+1)=b_i+2c_i(x_i+1-x_i)+3d_i(x_i+1-x_i)²=b_i+2c_ih_i+3d_ih_i ²

S_i+1′(x_i+1)=b_i+1+2c_i(x_i+1-x_i+1)+3d_i(x_i+1-x_i+1)²=b_i+1

Thus can obtain:

b_i+2c_ih_i+3d_ih_i ²-b_i+1=0

According to differential seriality, have:

S_i"(x_i+1)=S_i+1"(x_i+1) (i=0,1 ..., n-1)

Can obtain:

2c_i+6h_id_i-2c_i+1==0

If $m_i={S_i}^{\′\′\left(x_i\right)}=2c_i,$ Then have:

$d_i=\frac{m_{i+1}-m_i}{6h_i}$

By c_i, d_iSubstitute into y_i+h_ib_i+h_i ²c_i+h_i ³d_i==y_i+1Can obtain:

$b_i=\frac{y_{i+1}-y_i}{h_i}-\frac{h_i}{2}{m}_i-\frac{h_i}{6}(m_{i+1}-m_i)$

By b_i, c_i, d_iSubstitute into b_i+2c_ih_i+3d_ih_i ²-b_i+1=0 (i=0,1 ..., n-1)

Matrix equation can be obtained:

$h_i{m}_i+2(h_i+h_{i+1})m_{i+1}+h_{i+1}{m}_{i+2}=6\[\frac{y_{i+2}-y_{i+1}}{h_{i+1}}-\frac{y_{i+1}-y_i}{h_i}\]$

(2-3) from similar curved surface, gather the multiple back end including curved surface head and the tail end points, substitute into above-mentioned matrix equation and solve, obtain the cubic spline interpoliation function solved;

(2-4) according to the cubic spline interpoliation function tried to achieve, bringing the three dimensional local information of damaged part damaged tissues except affected bone into, thus obtaining the curved surface after recovery, being artificial prosthesis threedimensional model.

The present invention compared with prior art has techniques below feature:

1. set up and meet patient personalized prosthese threedimensional model. On the basis of three-dimensional geometry statistical model, utilize the tissue of CT 3-dimensional reconstruction defect, set up the prosthese model meeting patient's particular demands, and on this basis, it is determined that the size of prosthese fixture and installation site.

2. pair borrowed structure design optimization. Simulation prosthese is implanting the Mechanical Form after in human body in advance, finds the defect existed in prosthese geometry in time. Prosthese stress in human body and deformation situation can be simulated well, thus reaching to find in advance the purpose of borrowed structure defect by finite element analysis technology.

3. improve 3D and print accuracy and the production efficiency of prosthese. Utilizing the result of study of personalized prosthese modeling technique and finite element method, design prints software kit with the 3D realized towards prosthetic designs, promotes that 3D printing technique is in the further application of medical field.

Accompanying drawing explanation

Fig. 1 is the holistic approach flow chart of the present invention;

The existing several spinal prosthesis of Fig. 2 and fixture; Wherein Fig. 2 (a) is vertebral body prosthese, the scanning figure that Fig. 2 (b) is spinal fixation elements; The illustraton of model that Fig. 2 (c) is spinal fixation elements;

Fig. 3 is the artificial intervertebral disk Finite element analysis results under different shape, wherein analysis chart during Fig. 3 (a) stress non-for intervertebral disc, analysis chart when Fig. 3 (b) is for intervertebral disc stress.

Detailed description of the invention

Modeling and the result optimizing problem that prosthese exists in design production and clinical operation process is printed in order to solve 3D, the present invention, based on human body three-dimensional statistical geometric model, sets up according to CT image and meets the artificial prosthesis accurately of patient's particular/special requirement, fixture and tissue Integrated Model; By finite element method, analyze prosthese and change at the Mechanical Form within real human body, provide science data for the position of sound production of science of prosthese, the design of fixture size, prosthese hollow out and stress and deformation and Using prosthesis operation criticism analysis optimization. Finally, the software kit towards 3D printing that integrated design prosthese automatic modeling and borrowed structure optimize, it is achieved 3D prints prosthese model.

Before the formulation carrying out this programme, inventor's distribution according to tissue position, select to have installed the position of prosthese, such as select spinal prosthesis as researching and analysing object, by with a line doctor exchange research, manufacturer cooperates with prosthese, understanding and the analysis to existing multiple prosthese, designing points according to different prostheses and the effect of prosthese fixture, provide fundamental basis for follow-up integrated modelling. If Fig. 2 is existing several spinal prosthesis and fixture.

Defer to technique scheme, as it is shown in figure 1, the invention provides a kind of 3D based on finite element analysis to print personalized modeling method, below in conjunction with accompanying drawing, technical scheme is carried out detailed displaying.

A kind of 3D based on finite element analysis prints personalized modeling method, comprises the following steps:

Step one, to needing the skeleton part setting up artificial prosthesis to carry out three-dimensional reconstruction, obtains threedimensional model, this threedimensional model cuts and retains the model of part interested;

This step, by the process to skeleton image, establishes corresponding 3-D view set, lays the foundation for setting up skeleton three-dimensional geometry form statistical model and finite element analysis. Detailed process is, utilize MR or CT technology that human skeleton is carried out three-dimensional reconstruction, according to different CT values, CT image is carried out Threshold segmentation, on CT faultage image basis after singulation, it is filtered, fills, utilize iso-surface patch or volume drawing to obtain the threedimensional model of skeleton; In the three-dimensional model, threedimensional model being cut, obtain the model of part interested after cutting, this part interested is the model comprising patient's defect, has the three-dimensional data of subjects bones's defect part in this section in model; It is thus desirable to this part is individually taken out, it is simple to follow-up research processes.

The CT data of subjects bones's defect part in the model of part interested according to the symmetry of skeleton or are fitted according to the form law of human body three-dimensional statistical model, obtain artificial prosthesis threedimensional model by step 2;

The basic handling thinking of this step is, model according to the part interested obtained in step one, comprise the part of subjects bones's defect in this model, and utilize the measurement database of a Morphological Model, finding the model data identical with the model of part interested wherein, this model data is to set up with healthy human skeleton model; The model data in the model of current part interested and data base is utilized to compare matching, it is possible to obtain the threedimensional model of defect part, i.e. the threedimensional model of artificial prosthesis. Specifically comprise the following steps that

(1) the similar curved surface at bone damage position is found out.

Situation 1: if damaged part can restore according to the symmetry of skeleton and obtain, just the direct antimere according to patient's human body determines similar curved surface (i.e. the curved-surface structure of defect). Referring here to, if the part of bone damage is smaller, and human skeleton majority is column structure, so can find out the position symmetrical with damaged part on skeleton, extract the three-dimensional data of this position, be fitted with damaged part, finally give the similar curved surface of damaged part. Such as, one section of skeleton is analogized to one section of cylinder, somewhere defect on cylindrical outer surface, then with this position find out with the cylinder of its symmetry on be separated by another position of 180 °, the three-dimensional data of this position is extracted from the three-dimensional data of cylinder, it is fitted with defect place, the curved surface of defect can be obtained.

Situation 2: if damaged part is bigger, it is impossible to restore according to skeleton symmetry, then can be obtained the similar curved surface of damaged part by the method for data base's matching. Here data base refers to the data base preserving normal human's skeleton three-dimensional data, therefrom selects to determine similar curved surface with the three-dimensional data of the damaged part place identical skeleton of skeleton, specific as follows:

Set up skeleton data base, data base gathers normal human's skeleton data under different age group.

Classification in data base includes: sex, age bracket, height, body weight, skeleton label etc.

Wherein skeleton label refers to and is numbered by the 206 of human body pieces of skeletons, the corresponding one piece of skeleton of each numbering. What gather emphatically is that impaired probability is higher, and human normal activity has the skeleton of material impact, for instance skull, vertebrae and bones of limbs.

Under same group of sex, age (section), height (section), body weight (section), the three-dimensional data of certain block skeleton is gathered from the normal human's sample meeting this set condition, normal human's sample collection many groups, thus obtain multiple three-dimensional datas of certain block skeleton under same sex (section), age (section), height (section), body weight (section), preserve after data are averaged, as the standard three-dimensional data of this block skeleton under this group sex, age (section), height (section), body weight (section).After the same method, different sexes three-dimensional data of certain block skeleton standard under all ages and classes, height, body weight can be obtained, store it in skeleton data storehouse; The defect part of subjects bones can establish similar curved surface by the three-dimensional data of the standard of corresponding skeleton in these group data identical with same age, height, sex, body weight. As without corresponding data, then selected age, height, sex, the immediate one group of data of body weight.

(2) according to the similar curved surface found, cubic spline interpolation is utilized to obtain toroidal function.

Cubic spline interpoliation function representation is:

S_i(x)=a_i+b_i(x-x_i)+c_i(x-x_i)²+d_i(x-x_i)³

In above formula, i=0,1 ..., n-1; a_i,b_i, c_i,d_iRepresent 4n unknowm coefficient.

Comparison similarity surface, suppose there is n+1 data point on similar curved surface, is respectively as follows:

(x₀, y₀), (x₁, y₁), (x₂, y₂) ..., (x_n, y_n);

(2-1) material calculation h_i=x_i+1-x_i(i=0,1 ..., n-1), carry it into curvilinear function S_iIn (x);

(2-2) coefficient of cubic spline curve is calculated:

Have according to difference and seriality:

S_i(x_i)=y_i(i=0,1 ..., n-1)

Obtain:

a_i=y_i

According to S_i(x_i+1)=y_i+1(i=0,1 ..., n-1)

a_i+h_ib_i+h_i ²c_i+h_i ³d_i=y_i+1

Have according to differential seriality:

(x_i+1)=S_i+1′(x_i+1) (i=0,1 ..., n-1)

Then can release:

S_i′(x_i+1)=b_i+2c_i(x_i+1-x_i)+3d_i(x_i+1-x_i)²=b_i+2c_ih_i+3d_ih_i ²

S_i+1′(x_i+1)=b_i+1+2c_i(x_i+1-x_i+1)+3d_i(x_i+1-x_i+1)²=b_i+1

Thus can obtain:

b_i+2c_ih_i+3d_ih_i ²-b_i+1=0

According to differential seriality, have:

S_i″(x_i+1)=S_i+1"(x_i+1) (i=0,1 ..., n-1)

Can obtain:

2c_i+6h_id_i-2c_i+1=0

If $m_i={S_i}^{\′\′\left(x_i\right)}=2c_i,$ Then have:

$d_i=\frac{m_{i+1}-m_i}{6h_i}$

By c_i, d_iSubstitute into y_i+h_ib_i+h_i ²c_i+h_i ³d_i=y_i+1Can obtain:

$b_i=\frac{y_{i+1}-y_i}{h_i}-\frac{h_i}{2}{m}_i-\frac{h_i}{6}(m_{i+1}-m_i)$

By b_i, c_i, d_iSubstitute into b_i+2c_ih_i+3d_ih_i ²-b_i+1=0 (i=0,1 ..., n-1)

Matrix equation can be obtained:

$h_i{m}_i+2(h_i+h_{i+1})m_{i+1}+h_{i+1}{m}_{i+2}=6\[\frac{y_{i+2}-y_{i+1}}{h_{i+1}}-\frac{y_{i+1}-y_i}{h_i}\]$

(2-3) from similar curved surface, gather the multiple back end including curved surface head and the tail end points, substitute into above-mentioned matrix equation and solve, obtain the cubic spline interpoliation function solved;

Owing to the span of i is it can be seen that have n-1 formula, but there is n+1 unknown quantity, so that the differential of two-end-point is any limitation as, adopt the restriction of free boundary, i.e. S "=0 at this. It is embodied as m₀=0 and m_n=0, then the matrix equation solved is:

(2-4) according to the cubic spline interpoliation function tried to achieve, bringing the three dimensional local information of damaged part damaged tissues except affected bone into, thus obtaining the curved surface after recovery, being artificial prosthesis threedimensional model.

Step 3, design meets the fixture model that operation requires, and set up the tissue threedimensional model around damaged part, the tissue threedimensional model around artificial prosthesis threedimensional model, fixture model and damaged part is combined, obtains Integrated Model;

Different defect, sclerotin attribute and the factor such as age and body weight, the fixture that prosthese is used and fixed position are different, it is therefore desirable to integrated modelling. After generation meets the artificial prosthesis threedimensional model of patient personalized demand, import the fixture threedimensional model of clinical this prosthese supporting, utilize patient CT data, adjust the specification size of fixture, according to the paired observation to actual normal human's skeletal structure, manually add and around damaged part, have the actual tissue contacted with skeleton, such as the muscle of defect, ligament etc., by them with the prosthese built according to correct spatial relationship combination, form Integrated Model. The meaning of integrated modelling is in that, different defect, sclerotin attribute and the factor such as age and body weight, the fixture that prosthese is used and fixed position are different, therefore, prosthese fixture and fixed position are chosen enough instance datas, contrast in conjunction with mechanical analysis, select the fixture that every kind of prosthese is suitable and fixed position.

Existing several prosthese and fixture are as shown in Figure 2. These borrowed structures existing, owing to being unified production, its contour structures and mechanical property all determine that. But skeleton defect, shape are different, the actual influence to human body is also different, does not have concordance and uniformity. Thus after existing prosthese and fixture be applied on human body, it is impossible to fully meet the demand of personalization, cause that the actual functional capability of prosthese can not effectively play, also make the normal activity of patient be restricted, and easily develop complications. Therefore for different bone defects situations, prosthese and anchor structure should be designed pointedly.

Step 4, processes the Integrated Model gridding obtained and sets a property, and generates FEM mesh;

The ScanFE module of Simpleware software provides outstanding stress and strain model function, it is possible to threedimensional model is converted into grid model, thus we rely on ScanFE module to carry out the structure of grid model. When model is imported ScanFE, threedimensional model can be smoothed by ScanFE, arranges stress and strain model attribute on this basis and it is carried out stress and strain model, divides attribute and includes the size of unit, type etc. Consider computer resource and the restriction of the time of calculating, it is necessary to adopt different unit sizes according to particular problem. After stress and strain model completes, when FEM mesh is derived from ScanFE, need to give the material properties that each tissue is different, Young's modulus and Poisson's ratio are commonly used to describe the material properties of object, Poisson's ratio is defined as material and is stretched or compresses the ratio of its transverse strain and longitudinal strain when deforming upon, and it is the elastic constant of reflection material transversely deforming. Forward strain can be produced when elastomeric material bears normal stress, when deformation quantity is not above the elastic limit of respective material, the Young's modulus that ratio is this material that definition normal stress strains with forward, the description of hypothesis of passing through according to individual character, and this will not change with direction. So different bone material is adopted the closedown of Persian year and Young's modulus to make a distinction by we, and the integrated grid model generated the most at last imports in finite element analysis software ANSYS and is analyzed.

Step 5, carries out contrast test, the accuracy of the integrated grid model that checking previous step is set up with normal human body, the model beyond error allowed band carries out again demonstration and design;

The human body of healthy volunteer is carried out measurement and the collection of related data, as lumbar vertebra is carried out integrated modelling, gather multiple indexs such as the vertebral body length of healthy volunteer, the body weight of volunteer, the volunteer spinal curvature degree under certain given pose, verified by the data of healthy human body and the data variation of model after prosthese is installed. By simulating the posture of healthy volunteer, finite element analysis software ANSYS is used to apply similar load on model, load and calculating solves, generating cloud atlas, obtain the displacement of load by observing cloud atlas clearly, curvature etc. changes, the data that the data variation of contrast finite element mechanical model and volunteer measure under given pose, utilize the theory of mathematical statistics, the effectiveness of model is proved, the model beyond error allowed band is carried out again demonstration and design. The purpose of this step and last step is in that, Integrated Model data for setting up have one to analyze process intuitively, by the analysis to its mechanical characteristic, contrast normal human is the situation of skeleton, tissue institute stress under same mechanical condition, can verify that the Integrated Model of foundation whether can practical requirement, as met, then can adopt this Integrated Model; Otherwise utilize analysis result for the data message improving offer necessity of model, can to instruct for choosing of mould shapes, material etc.

Step 6, applies different constraints and load simulated postoperative human body stressing conditions at different conditions to the Integrated Model after checking, and the optimizing research for model provides analytical data;

According to the Integrated Model after checking, with reference to postoperative human body real-life situations, set up the stressing conditions in different constraints and load hypothesized model prosthese human body after surgery, it is thus achieved that the stress cloud atlas of model.

Physical attribute for prosthese, such as geometric size, thickness, hollow out degree etc., simultaneously take account of length and the size of fixture, by control variate method, analyze the different factor impact on the biomechanics of Integrated Model, being illustrated in figure 3 the artificial intervertebral disk Finite element analysis results under different shape, wherein color does not exist together and represents that the stressing conditions at this position is different from surrounding; Can recognize, by image, the dynamics distribution situation that bone prosthesis bears under different stressing conditions intuitively, it is analyzed, for optimizing the design of prosthese model, thus constructing the borrowed structure being best suitable for patient demand.

Step 7, is printed Integrated Model by 3D printing technique, obtains meeting the prosthese model of human body actual demand.

Personalization prosthese modeling technique and finite element analysis function are attached to 3D print in software kit, are beneficial to the production of prosthese model.

Claims (4)

1. the 3D based on finite element analysis prints personalized modeling method, it is characterised in that comprise the following steps:

Step one, to needing the skeleton part setting up artificial prosthesis to carry out three-dimensional reconstruction, obtains threedimensional model, this threedimensional model cuts and retains the model of part interested;

The CT data of subjects bones's defect part in the model of part interested according to the symmetry of skeleton or are fitted according to the form law of human body three-dimensional statistical model, obtain artificial prosthesis threedimensional model by step 2;

Step 3, design meets the fixture model that operation requires, and set up the tissue threedimensional model around damaged part, the tissue threedimensional model around artificial prosthesis threedimensional model, fixture model and damaged part is combined, obtains Integrated Model;

Step 4, processes the Integrated Model gridding obtained, generates FEM mesh;

Step 5, carries out contrast test, the accuracy of the integrated grid model that checking previous step is set up with normal human body, the model beyond error allowed band carries out again demonstration and design;

Step 6, applies different constraints and load simulated postoperative human body stressing conditions at different conditions to the Integrated Model after checking, and the optimizing research for model provides analytical data;

Step 7, is printed Integrated Model by 3D printing technique, obtains meeting the prosthese model of human body actual demand.

2. the described 3D based on finite element analysis as claimed in claim 1 prints personalized modeling method, it is characterised in that the detailed process of step one includes:

Utilize MR or CT technology that human skeleton is carried out three-dimensional reconstruction, according to different CT values, CT image is carried out Threshold segmentation, on CT faultage image basis after singulation, be filtered, fill, utilize iso-surface patch or volume drawing to obtain the threedimensional model of skeleton; In the three-dimensional model, threedimensional model being cut, obtain the model of part interested after cutting, this part interested is the model comprising patient's defect.

3. the 3D based on finite element analysis as claimed in claim 1 prints personalized modeling method, it is characterised in that the detailed process of step 2 includes:

(1) the similar curved surface at bone damage position is found out

Situation 1: if damaged part can restore according to the symmetry of skeleton and obtain, just the direct antimere according to patient's human body determines similar curved surface;

Situation 2: if damaged part is bigger, it is impossible to restore according to skeleton symmetry, then can be obtained the similar curved surface of damaged part by the method for data base's matching; Here data base refers to the data base preserving normal human's skeleton three-dimensional data, therefrom selects to determine similar curved surface with the three-dimensional data of the damaged part place identical skeleton of skeleton;

(2) according to the similar curved surface found, cubic spline interpolation method is utilized to obtain toroidal function; Then artificial prosthesis threedimensional model is obtained.

4. the 3D based on finite element analysis as claimed in claim 3 prints personalized modeling method, it is characterised in that in step 2, the detailed process of (2) including:

Cubic spline interpoliation function representation is:

S_i(x)=a_i+b_i(x-x_i)+c_i(x-x_i)²+d_i(x-x_i)³

In above formula, i=0,1 ..., n-1; a_i, b_i, c_i, d_iRepresent 4n unknowm coefficient.

Similar curved surface suppose there is n+1 data point, be respectively as follows:

(x₀, y₀), (x₁, y₁), (x₂, y₂) ..., (x_n, y_n);

(2-1) material calculation h_i=x_i+1-x_i(i=0,1 ..., n-1), carry it into curvilinear function S_iIn (x);

(2-2) coefficient of cubic spline curve is calculated:

Have according to difference and seriality:

S_i(x_i)=y_i(i=0,1 ..., n-1)

Obtain:

a_i=y_i

According to S_i(x_i+1)=y_i+1(i=0,1 ..., n-1)

a_i+h_ib_i+h_i ²c_i+h_i ³d_i=y_i+1

Have according to differential seriality:

(x_i+1)=S_i+1(x_i+1) (i=0,1 ..., n-1)

Then can release:

S_i′(x_i+1)=b_i+2c_i(x_i+1-x_i)+3d_i(x_i+1-x_i)²=b_i+2c_ih_i+3d_ih_i ²S_i+1′(x_i+1)=b_i+1+2c_i(x_i+1-x_i+1)+3d_i(x_i+1-x_i+1)²=b_i+1

Thus can obtain:

b_i+2c_ih_i+3d_ih_i ²-b_i+1=0

According to differential seriality, have:

S_i′′(x_i+1)=S_i+1′′(x_i+1) (i=0,1 ..., n-1)

Can obtain:

2c_i+6h_id_i-2c_i+1=0

IfThen have:

By c_i, d_iSubstitute into y_i+h_ib_i+h_i ²c_i+h_i ³d_i=y_i+1Can obtain:

By b_i, c_i, d_iSubstitute into b_i+2c_ih_i+3d_ih_i ²-b_i+1=0 (i=0,1 ..., n-1)

Matrix equation can be obtained:

(2-3) from similar curved surface, gather the multiple back end including curved surface head and the tail end points, substitute into above-mentioned matrix equation and solve, obtain the cubic spline interpoliation function solved;

(2-4) according to the cubic spline interpoliation function tried to achieve, bringing the three dimensional local information of damaged part damaged tissues except affected bone into, thus obtaining the curved surface after recovery, being artificial prosthesis threedimensional model.