Auxiliary assessment method and device for damaged mandible

Abstract

The present invention discloses an auxiliary evaluation method and device for a damaged mandible, comprising an image acquisition module for acquiring CT images of the damaged mandible; a mandibular fracture model construction module for constructing a mandibular fracture model based on the CT images; a numerical analysis model construction module for constructing a numerical analysis model based on the mandibular fracture model; a mathematical model construction module for the damaged mandible for constructing a mathematical model of the fixed position and angle of the titanium plate after mandibular fracture repair based on the numerical analysis model; and an evaluation module for evaluating the quality of mandibular fracture repair based on the mathematical model. The present invention can quickly construct a model of a damaged mandibular fracture, and the constructed evaluation model is accurate. The obtained titanium plate is installed in a reasonable and reliable position and angle on the mandible, avoiding stress concentration and secondary human damage after installation.

Description

Technical Field

[0001] The present invention belongs to the technical field of damaged mandibular fracture model assessment, and relates to an auxiliary assessment method and device for damaged mandibular fracture. Background Art

[0002] With rising health awareness and the deepening integration of medicine and engineering, surgical treatment options are evolving towards higher efficiency and precision. The mandible, the only movable bone in the face, is located in the lower part of the face and is the largest bone in the face. It is prone to fractures in various accidents, accounting for 23%-42% of facial fractures. These fractures can affect patients' chewing, biting, and other physiological functions. Facial defects can also place a psychological burden on patients and reduce their quality of life.

[0003] Mandibular fractures can be treated with conservative treatment or open surgery. Conservative treatment avoids the trauma of surgery, but requires the installation of a traction device on the patient's face. This treatment method has a long recovery time and restricts the patient's daily life. Another method is a strong internal fixation technique that uses titanium plates to fix the fracture position. The fracture is exposed through surgery and fixed with titanium plates. This method has a short treatment cycle and a high success rate. However, the fixation of titanium plates is often based on the doctor's clinical experience and lacks theoretical guidance. At the same time, the metal mechanical properties of titanium plates differ greatly from those of bone tissue, which can easily cause stress concentration. This may cause stress conflict between the titanium plate and the bone after fixation, causing the titanium plate to loosen or even break, resulting in secondary surgery, increasing the patient's pain and treatment time. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an auxiliary evaluation method and device for a damaged mandible, so as to solve the technical problems existing in the prior art.

[0005] The technical solution adopted by the present invention is: an auxiliary assessment method for damaged mandible, the method comprising the following steps:

[0006] S1: Acquire CT images related to the damaged mandible;

[0007] S2: Based on the CT image of the damaged mandible obtained in S1, an initial model of the mandible was established using the Mimics medical image processing platform. The surface of the initial model was optimized using the reverse engineering processing platform. The optimized initial model was used to simulate the mandibular fracture model in 3D design software, and the titanium plate was assembled with the mandible.

[0008] S3: Constructing a numerical analysis model of the mandible: The mandibular fracture model obtained by assembling the titanium plate and the mandible obtained in S2 is imported into the simulation computing platform Abaqus for simulation analysis to complete the construction of the numerical analysis model of the mandible;

[0009] S4: Construct a mathematical model of the damaged mandible: Based on the data of the numerical analysis model obtained in S3, construct a mathematical model of the titanium plate fixation position and angle after mandibular fracture repair;

[0010] S5: Evaluate the restoration quality based on the mathematical model.

[0011] In S1, a medical image CT device was used to collect CT images related to the mandible, which were grayscale images with a size of 604×640 and a layer thickness of 0.25 mm.

[0012] When a medical image CT device scans, it scans from the cervical spine to the upper eye socket and then saves the image in DICOM format.

[0013] The specific method in S2 is: import the CT image into the Mimics medical image processing platform, check that there are no errors in the horizontal, coronal and sagittal planes, generate the corresponding mask according to the bone threshold pre-set by the software, extract the facial bones, and then use regional growing to remove the parts not connected to the mandible, and then use the mask editing tool to erase the remaining parts connected to the mandible, and finally generate the initial three-dimensional model. The initial model has a large number of triangles, and there are defects such as burrs, and damage on the surface of the model. It is imported into the reverse engineering processing platform Geomagic and enters the polygon processing stage. In this stage, the triangular facets are optimized, nails and redundant triangular faces are deleted, and the surface of the model is smoothed, smoothed, partially ground and repaired. The quality of the triangular mesh can be achieved for constructing the surface. The requirements of the patch; after the triangular patch repair is completed, the surface mesh is divided. The model needs to be divided into blocks, and the surface is fitted into a rectangle according to the structural characteristics of the model. The corresponding feature boundaries are arranged on the model. After the feature boundary is constructed, the surface of the constructed model will be divided into several parts, and the model will construct the surface patch according to the constructed feature boundary. However, at this time, the surface patch has a small surface patch angle and height corner point, and the surface cannot be successfully constructed. The surface patch needs to be moved and added in the constructed feature boundary to finally achieve a more regular surface patch structure. Finally, the fitted surfaces are merged to reduce the number of surfaces and converted into a commonly used 3D model format. Boolean operations are performed in the 3D design software platform to construct cortical bone and cancellous bone, simulate various fractures, and add titanium plates to the model to simulate the fracture of the titanium plate and the model.

[0014] The specific method in S3 is as follows: the 3D model format is exported in X_T format in the 3D design software platform, and the X_T format is imported into the simulation calculation platform Abaqus. The material properties of titanium alloy, cortical bone, and cancellous bone are established. Flexible springs are used to replace the masseter, temporalis, lateral pterygoid, and medial pterygoid muscles required for mandibular movement. The size of the network is determined by successively reducing the mesh size and increasing the mesh density.

[0015] The specific method in S4 is as follows: the fracture site is defined as the fracture line, the fracture line is taken as the 0° line, the counterclockwise angle is the positive angle, the grid, load, and boundary conditions are controlled to be consistent, only the fixed angle of the titanium plate is changed, a simulation experiment is performed every 5°, and the stress and displacement of the mandible, and the stress and displacement of the titanium plate are collected; according to the principle that the closer the determination coefficient is to 1, the closer the root mean square is to 0, and the scatter plot of the function, the mathematical model of the fixed angle and the stress and displacement of the mandible, and the stress and displacement of the titanium plate are obtained, the mid-perpendicular line of the wound is taken as the zero line, the zero line is defined as the positive direction toward the molar area, and the zero line is defined as the negative direction toward the mandibular bottom, the grid, load, and boundary conditions are controlled to be consistent, only the fixed position of the titanium plate is changed, and a simulation experiment is performed every 1 mm from -9 to 9, and the stress and displacement of the mandible, and the stress and displacement of the titanium plate are also collected; according to the principle that the closer the determination coefficient is to 1, the closer the root mean square is to 0, and the scatter plot of the function, the mathematical model of the fixed angle position of the titanium plate and the stress and displacement of the mandible, and the stress and displacement of the titanium plate are obtained.

[0016] The variation law of mandibular stress y1 with the change of titanium plate fixation angle x is obtained:

[0017]

[0018] Where: k0, a i 、b i 、k i and g i To pass Figure 10 The coefficient value obtained by fitting the scatter plot data of the angle and mandibular stress simulation experiment, x represents the fixed angle of the titanium plate, and y1 represents the mandibular stress corresponding to a certain fixed angle x;

[0019] As the titanium plate fixation angle x changes, the mandibular displacement y2 changes:

[0020]

[0021] Where: a i ′, b i ′,k i ′ and γ i ' is passed Figure 11 The coefficient value obtained by fitting the scatter plot data of the angle and mandibular displacement simulation experiment, x represents the fixed angle of the titanium plate, y2 represents the mandibular displacement corresponding to a certain fixed angle x, i = 1-4;

[0022] As the fixed angle x of the titanium plate changes, the change law of the titanium plate stress y3 is:

[0023]

[0024] Where: k0″, ai ″, b i ″,k i ″ and γ i ″To pass Figure 12 The coefficient value obtained by fitting the scatter data of the angle and titanium plate stress simulation experiment, x represents the fixed angle of the titanium plate, y3 represents the stress value of the titanium plate corresponding to a certain fixed angle x, i = 1-4;

[0025] As the fixed angle x of the titanium plate changes, the change law of the titanium plate displacement y4 is:

[0026]

[0027] Where: a i ″′,b i ″′,k i ″′ is the coefficient value obtained by fitting the 13-angle and titanium plate displacement simulation experimental data graph, x represents the fixed angle of the titanium plate, y4 represents the titanium plate displacement corresponding to a certain fixed angle x, and i=1-2.

[0028] As the titanium plate fixation position x1 changes, the change pattern of mandibular stress y5 is as follows:

[0029]

[0030] Where: and To pass Figure 15 The coefficient value obtained by fitting the scatter data of the distance and mandibular stress simulation experiment, x1 represents the fixed position of the titanium plate, and y5 represents the mandibular stress corresponding to a certain fixed position x1;

[0031] As the titanium plate fixation position x1 changes, the mandibular displacement y6 changes:

[0032]

[0033] Where: and To pass Figure 16 The coefficient values ​​obtained by fitting the scatter plot data of the distance and mandibular displacement simulation experiment, i = 1-2, x1 represents the fixed position of the titanium plate, and y7 represents the mandibular displacement corresponding to a certain fixed position 1;

[0034] As the fixed position x1 of the titanium plate changes, the change law of the titanium plate stress y8 is:

[0035]

[0036] Where: and for Figure 17The coefficient value obtained by fitting the scatter data of the distance and titanium plate stress simulation experiment. x1 represents the fixed position of the titanium plate, and y7 represents the stress of the titanium plate corresponding to a certain fixed position x1. As the fixed position x1 of the titanium plate changes, the change law of the titanium plate displacement y is:

[0037]

[0038] Where: and for Figure 17 The coefficient value obtained by fitting the scatter data graph of the distance and titanium plate stress simulation experiment, x1 represents the fixed position of the titanium plate, and y8 represents the displacement of the titanium plate corresponding to a certain fixed position x1.

[0039] An auxiliary assessment device for damaged mandible, comprising:

[0040] An image acquisition module, used for acquiring CT images of the damaged mandible;

[0041] Mandibular fracture model construction module, which constructs a three-dimensional mandibular fracture model repaired with titanium plates and mandible based on CT images;

[0042] The numerical analysis model construction module uses the simulation computing platform to construct a numerical analysis model based on the mandibular fracture model;

[0043] A mathematical model construction module for the damaged mandible, which constructs a mathematical model of the titanium plate fixation position and angle after mandibular fracture repair based on the numerical analysis model and the data obtained from the numerical analysis model;

[0044] Evaluation module: Based on the corresponding function relationship of the mathematical model, it is mapped into the relationship between color partitions and the corresponding titanium plate fixation position and angle, and the quality of mandibular fracture repair is evaluated through color partitions.

[0045] Beneficial effects of the present invention: Compared with the prior art, the effects of the present invention are as follows:

[0046] 1) The evaluation method obtained by the present invention can quickly construct a model of damaged mandibular fractures. The constructed evaluation model is accurate, and the obtained titanium plate is installed in the mandibular at a reasonable and reliable position and angle, avoiding stress concentration and secondary human damage after installation;

[0047] 2) Through the CT machine, it is possible to quickly obtain a CT image of the damaged mandible, and based on the 3D reconstruction function of the CT image, a 3D model of the damaged mandible is constructed to obtain an initial model. The 3D model constructed based on the CT data and the medical image processing platform is relatively rough, with defects such as spots, burrs, and burrs on the surface. With the help of the Mimics medical image processing platform, surface optimization and surface merging are performed. Due to the differences in size and characteristics of each patient's body parts, traditional implants or orthoses are often difficult to fit completely, resulting in unsatisfactory protection and rehabilitation effects during use. However, in the Mimics medical image processing platform of the reverse engineering processing platform, the corresponding model can be easily built, and a fully fitting implant can be designed, greatly improving the level of personalization and precision of the implant. After the resection of the mandibular lesion, the design of a personalized mandibular osteotomy guide can be completed to ensure the precise repair of the mandibular defect;

[0048] 3) The restored 3D model is analyzed using finite element analysis technology to obtain a mathematical module that simulates the stress magnitude, distribution, and displacement changes of the mandible when subjected to external force. The restored 3D model is evaluated based on these changes, and the evaluation is reasonable and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of the process implementation of the present invention;

[0050] Figure 2 This is the initial three-dimensional model of the mandible;

[0051] Figure 3 It is a defect map of the initial three-dimensional model surface;

[0052] Figure 4 It is the surface patch of the initial three-dimensional model and the trimmed model;

[0053] Figure 5 is the surface fitting diagram of the initial three-dimensional model;

[0054] Figure 6 The initial three-dimensional model constructs the cortical bone and cancellous bone maps;

[0055] Figure 7 This is the assembly diagram of the initial three-dimensional model mandible and titanium plate;

[0056] Figure 8 It is the determination diagram of the mandibular boundary conditions of the initial three-dimensional model;

[0057] Figure 9 These are the stress and displacement cloud maps of the mandible and titanium plate at 25°, including: (a) stress cloud map of the mandible at 25°; (b) displacement cloud map of the mandible at 25°; (c) stress cloud map of the titanium plate at 25°; (d) displacement cloud map of the titanium plate at 25°;

[0058] Figure 10 is the graph of angle and jaw stress;

[0059] Figure 11 is a graph of angle and jaw displacement;

[0060] Figure 12 is the angle and titanium plate stress curve;

[0061] Figure 13 is a graph of angle and titanium plate displacement;

[0062] Figure 14 The stress and displacement cloud diagrams of the mandible and titanium plate at the zero line, including (a) stress cloud diagram of the mandible at the zero line; (b) displacement cloud diagram of the mandible at the zero line; (c) stress cloud diagram of the titanium plate at the zero line; (d) displacement cloud diagram of the titanium plate at the zero line;

[0063] Figure 15 is the graph of distance and jaw stress;

[0064] Figure 16 is a graph of distance and jaw displacement;

[0065] Figure 17 is a graph of distance and titanium plate stress;

[0066] Figure 18 is a graph of distance and titanium plate displacement;

[0067] Figure 19 This is an example diagram, in which (a) the position of the titanium plate in the top view in CT; (b) the position of the titanium plate in the side view in CT; (c) the position of the titanium plate in the three-dimensional model; and (d) the measured position of the titanium plate. DETAILED DESCRIPTION

[0068] The present invention will be further described below with reference to specific embodiments.

[0069] Example 1: A method for assisting the assessment of damaged mandible, the process is as follows Figure 1 As shown, medical equipment is used to capture CT images of the mandible. An initial 3D model of the mandible is constructed using a medical modeling platform. The model surface is optimized using a reverse engineering processing platform. The optimized model is then used in a 3D design platform to create a fracture model and assemble the titanium plate with the mandible. For common mandibular angle fractures, simulation analysis is used to understand the biomechanical properties of the mandible, collect data, and explore the mathematical model of the relationship between the titanium plate, the mandible, and the stress and displacement of the titanium plate at different fixation positions and angles. The appropriateness of the titanium plate fixation position and angle is then qualitatively determined. The repair tool displays different colors when the user slides to select the titanium plate fixation position and angle.

[0070] Step 1: Use professional medical equipment to acquire CT images of the mandible. The acquired grayscale images are 604×640 pixels with a slice thickness of 0.25 mm. Use professional medical equipment to acquire CT images of the mandible. The acquired grayscale images are 640×640 pixels with a slice thickness of 0.25 mm. Specifically, to ensure the integrity of the mandible, the CT machine scans from the cervical spine to the upper orbit. The images are then saved in DICOM format for easy transfer between different devices.

[0071] Step 2: Use a multi-platform collaborative method to construct a three-dimensional model of the mandible. The CT image containing the mandible obtained in step 1 is used to build an initial model of the mandible using the Mimics medical image processing platform. The surface of the initial model is optimized using the reverse engineering processing platform Geomagic. The mandibular fracture is simulated in the conventional three-dimensional design software SolidWorks, and the titanium plate and mandible are assembled. The CT image is imported into the Mimics medical image processing platform. After checking that there are no errors in the horizontal, coronal, and sagittal planes, the corresponding mask is generated according to the bone threshold value pre-set by the software [226,3071]. Because the threshold value of the mandible is the same as that of the entire facial tissue, the entire facial skeleton will be extracted. Then, regional growth is used to remove the parts that are not connected to the mandible. Because the condyle of the mandible is connected to the maxilla, the mask editing tool is also used to erase the remaining parts connected to the mandible. Finally, the initial three-dimensional model is generated, as shown in the figure. Figure 2 The initial model created using Mimics is stored in STL format. The STL format is a shell model composed of triangular faces. The number of triangular faces is huge, and the model surface also has defects such as burrs, breakage, etc. Figure 3 As shown, it is imported into the reverse engineering processing platform Geomagic and enters the polygon processing stage. In this stage, the triangular facets are optimized, spikes and redundant triangular faces are deleted, and the surface of the model is smoothed, smoothed, partially polished, and holes are repaired. This process has extremely little impact on the shape of the model and can make the quality of the triangular mesh meet the requirements for constructing surface patches. After the triangular facets are repaired, the surface mesh is divided. The model needs to be divided into blocks, and the corresponding feature boundaries are arranged on the model according to the structural characteristics of the model and the requirement that the surface fitting is preferably rectangular. After the feature boundary is constructed, the surface of the constructed model will be divided into several parts, and the model will construct the surface patch based on the constructed feature boundary. However, at this time, the surface patch has a small angle and height corner point, and the surface cannot be successfully constructed. It is also necessary to move and add surface patches in the constructed feature boundary to finally achieve a more regular surface patch structure, as shown in the figure. Figure 4 As shown, the fitted surfaces are finally merged to reduce the number of surfaces and converted into a commonly used three-dimensional model format, such as Figure 5 Then, the cancellous bone is constructed by offsetting, and the cortical bone is constructed by Boolean operation in the 3D design software platform SolidWorks. The cortical bone and cancellous bone are fused together by inserting parts, as shown in the figure. Figure 6 Model various fractures, design titanium nail holes on the mandible, and complete the design and assembly of titanium plates, as shown in Figure 7 As shown, it lays the foundation for the construction of subsequent numerical analysis models and also provides a vivid expression for the formulation of surgical plans.

[0072] Step 3: Construct a numerical analysis model of the mandible. Import the model obtained in step 2 into the simulation calculation platform Abaqus, set the material and boundary conditions of the mandible, perform simulation analysis, and complete the construction of the numerical analysis model of the mandible. In the three-dimensional design platform, export this assembly in X_T format, and import it into the simulation calculation platform Abaqus by importing parts. Then establish the three material properties of titanium alloy, cortical bone, and cancellous bone. The elastic modulus of titanium alloy is 120000, the elastic modulus of cortical bone is 13700, and the elastic modulus of cancellous bone is 1370. The Poisson's ratio is 0.3, and the material properties are assigned to the corresponding parts. The loading method is concentrated stress to simulate single-point occlusion. The titanium nail and the titanium nail hole on the mandible are set as binding constraints, friction constraints are used at the fracture wound, and flexible springs are used to replace the masseter, temporalis, lateral pterygoid, medial pterygoid and other muscles necessary for mandibular movement, and the condylar protrusion is rigidly fixed, such as Figure 8 As shown in Figure 2, the size of the network is determined by successively reducing the grid size and increasing the grid density.

[0073] Step 4: Construct a mathematical model of the damaged mandible. According to the operation in step 3, collect data experimentally, find the relationship between the data, and construct a mathematical model of the fixed position and angle of the titanium plate after mandibular fracture repair. Define the fracture site as the fracture line, with the fracture line as the 0° line and the counterclockwise angle as the positive angle. Keep the grid, load, boundary conditions and other variables consistent. Only change the fixed angle of the titanium plate. Perform a simulation experiment every 5° from 25° to 155°. Figure 9 As shown, the stress-displacement diagram at 25° collects the stress and displacement of the mandible and the stress and displacement of the titanium plate. According to the principle that the closer the coefficient of determination is to 1, the closer the root mean square is to 0, and the scatter plot of the function is as follows Figure 10-13 As shown, the titanium plate fixation angle and mandibular stress are shown in formula 1, the titanium plate fixation angle and mandibular displacement are shown in formula 2, the titanium plate fixation angle and titanium plate stress are shown in formula 3, and the titanium plate fixation angle and titanium plate displacement are shown in formula 4.

[0074]

[0075]

[0076]

[0077]

[0078] The vertical line of the wound is taken as the zero line. The zero line is defined as the positive direction toward the molar area and the zero line is defined as the negative direction toward the mandibular bottom. The grid, load, and boundary conditions are controlled to be consistent. Only the fixed position of the titanium plate is changed. The simulation experiment is performed every 1mm from -9 to 9. Figure 14 As shown, it is the stress and displacement cloud diagram of the mandible and titanium plate at the zero line. The stress and displacement of the mandible and the stress and displacement of the titanium plate are also collected. According to the principle that the closer the coefficient of determination is to 1, the closer the root mean square is to 0, and the scatter diagram of the function is as follows Figure 15-18 As shown, the titanium plate fixed position and mandibular stress are obtained as shown in Formula 5, the titanium plate fixed position and mandibular displacement are shown in Formula 6, the titanium plate fixed position and titanium plate stress are shown in Formula 7, and the titanium plate fixed position and titanium plate displacement are shown in Formula 8.

[0079] y5=6.74-0.5221cos(0.3506x1)-0.0391sin(0.3506x1)+0.6213cos(0.7012x1)+0.0715sin(0.7012x1)-0.0444cos(1.0518x1)+0.122 6sin(1.0518x1)+0.113cos(1.4024x1)-0.0927sin(1.4024x1)-0.2037cos(2.1036x1)-0.1737sin(2.4542x1)+0.0984cos(2.8048x1) (5)

[0080]

[0081] y7=2.268-0.0367cos(0.3221x1)-0.01sin(0.3221x1)-0.02414sin(0.6442x1)+0.03399cos(0.9663x1)-0.03031sin(0.9663x1)+0.04406cos(1.2884x1)+0.0435sin(1.2884x1)-0.01213cos(1.6105x1)+0.0086sin(1.6105x1)+0.043cos(1.9326x1)+0.0432sin(1.933x1)-0.02058cos(2.2547x1)-0.0163sin(2.255x1)+0.0075cos(2.5768x1)-0.2322sin(2.5768x1) (7)

[0082] y8=1.632-0.0265cos(0.2735x1)+0.0124sin(0.2735x1)+0.0047cos(0.547x1)-0.019sin(0.547x1)+0.0112sin(0.8205x1)+0.00613cos(1.094x1)-0.0075sin(1.094x1)+0.0079sin(1.3675x1) (8)

[0083] Step 5: Evaluate the mandibular restoration model based on the mathematical model from Step 4: Based on the mathematical model obtained in Step 4, a mandibular assisted restoration evaluation module was designed using MATLAB. Specifically, the module qualitatively categorizes the appropriateness of the titanium plate fixation position and angle. When the user slides to select the titanium plate fixation position and angle, the restoration tool displays different colors, facilitating practical operation. The user interface for the "Mandibular Restoration Assistance Tool" is designed, including two buttons: "Titanium Plate Fixation Position" and "Titanium Plate Fixation Angle." The menu bar includes the "File," "Exit," and "About" tabs. The "File" tab also allows users to jump to any sub-interface. Clicking "Titanium Plate Fixation Angle" on the main interface or the "File" tab on the titanium plate fixation angle sub-interface displays the titanium plate fixation angle sub-interface. The menu bar of this interface displays jaw stress, jaw displacement, titanium plate stress, and titanium plate displacement. Clicking the corresponding tab switches interfaces, and clicking Exit returns the user to the main interface. Key controls include sliders, editable numeric fields, instrument panels, and static text fields. The slider is for user interaction. Users slide the slider to select a value, and the value will also be displayed in the editable value box above the slider. At the same time, when sliding the slider, the pointer of the instrument panel will rotate accordingly. When the pointer stays in the red area, it means that the angle of titanium plate fixation is not appropriate; when the pointer stays in the yellow area, it means that the angle of titanium plate fixation is acceptable; when the pointer stays in the green area, it means that the angle of titanium plate fixation is appropriate. This three-level design is very necessary because of the individual differences in mandibles and different fracture conditions. Doctors can make choices within the yellow and green areas based on clinical experience, which enhances flexibility.

[0084] Click on "Titanium Plate Fixed Position" on the main interface or the titanium plate fixed position under the "File" tab, and the interface will enter the titanium plate fixed position sub-interface. The layout design of the main menu and controls of this interface is similar to the titanium plate fixed angle sub-interface. The value is also selected by sliding the slider, and the pointer will point to different areas. When the pointer stays in the red area, it means that the titanium plate fixed position is inappropriate; when the pointer stays in the yellow area, it means that the titanium plate fixed position is acceptable; when the pointer stays in the green area, it means that the titanium plate fixed position is appropriate. After clicking the "Exit" button, a prompt box will appear. The default operation is not to exit to avoid user misoperation. If you do not continue to exit, you can switch interfaces for operation. The two sub-interfaces of titanium plate fixed angle and titanium plate fixed position are used to assist doctors in determining the titanium plate fixed position.

[0085] However, these analyses involve multiple processing platforms and require a certain level of engineering background knowledge. This can be a long learning curve for physicians, who are the intended users. For physicians without an engineering background, conducting multiple simulations followed by data analysis is not optimal, and is both time-consuming and laborious, making it difficult to implement in practice. Therefore, a mandibular assisted prosthesis tool with a simple user interface was developed to facilitate its use in clinical practice.

[0086] Example 2: An auxiliary assessment device for damaged mandible, comprising:

[0087] An image acquisition module, used for acquiring CT images of the damaged mandible;

[0088] Mandibular fracture model construction module, which constructs a three-dimensional mandibular fracture model repaired with titanium plates and mandible based on CT images;

[0089] The numerical analysis model construction module uses the simulation computing platform to construct a numerical analysis model based on the mandibular fracture model;

[0090] A mathematical model construction module for the damaged mandible, which constructs a mathematical model of the titanium plate fixation position and angle after mandibular fracture repair based on the numerical analysis model and the data obtained from the numerical analysis model;

[0091] Evaluation module: Based on the corresponding function relationship of the mathematical model, it is mapped into the relationship between color partitions and the corresponding titanium plate fixation position and angle, and the quality of mandibular fracture repair is evaluated through color partitions.

[0092] The implementation methods of each of the above modules are implemented using the corresponding methods in Example 1. The above-mentioned evaluation device can quickly construct a model of damaged mandibular fractures. The constructed evaluation model is accurate, and the obtained titanium plate is installed in a reasonable and reliable position and angle on the mandibular bone, avoiding stress concentration and preventing secondary human damage after installation.

[0093] Model application effect: a case of mandibular angle fracture ( Figure 19 ), the case has been surgically fixed by the doctor using a titanium plate. The postoperative CT data was collected and compared with the model calculation results. Figure 19 (a) (b) in the figure shows the position of titanium plate fixation in medical clinic in CT image. In order to facilitate the measurement of the position of titanium plate fixation, a three-dimensional model is established in Mimics, such as Figure 19 As shown in (c), the position where the titanium plate is fixed is measured and marked according to the figure, as shown in Figure 19As shown in (d), the illustrated dimensions are approximately 6.09 times the actual jaw size. This indicates that the distance between the titanium plate and the midline is 35.88 / 6.09 = 5.89 mm. Based on the mathematical model constructed in this invention, the stress value of placing the titanium plate at this location is less than 1 / 3 of the maximum stress, which is determined to be a feasible placement area based on the mathematical model. The calculated results are consistent with the physician's experience. The angle between the fracture line and the titanium plate is 88.61°. Based on the model calculations, the stress value of placing the titanium plate at this angle is also less than 1 / 3 of the maximum stress, which is determined to be a feasible placement area based on the mathematical model. The calculated results are consistent with the physician's experience, demonstrating that the constructed mathematical model can be used to assist physicians in surgical planning.

[0094] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for assisting in the assessment of damaged mandible, characterized by: The method comprises the following steps: S1: Acquire CT images related to the damaged mandible; S2: Based on the CT image of the damaged mandible obtained in S1, an initial model of the mandible was established using the Mimics medical image processing platform. The surface of the initial model was optimized using the reverse engineering processing platform. The optimized initial model was used to simulate the mandibular fracture model in 3D design software, and the titanium plate was assembled with the mandible. S3: Constructing a numerical analysis model of the mandible: The mandibular fracture model obtained by assembling the titanium plate and the mandible obtained in S2 is imported into the simulation computing platform Abaqus for simulation analysis to complete the construction of the numerical analysis model of the mandible; S4: Construct a mathematical model of the damaged mandible: Based on the data of the numerical analysis model obtained in S3, construct a mathematical model of the titanium plate fixation position and angle after mandibular fracture repair; S5: Assessment of restoration quality based on mathematical models; The specific method in S4 is: the fracture site is defined as the fracture line, the fracture line is taken as the 0° line, the counterclockwise angle is the positive angle, the grid, load, and boundary conditions are controlled to be consistent, only the fixed angle of the titanium plate is changed, a simulation experiment is performed every 5°, and the stress and displacement of the mandible, and the stress and displacement of the titanium plate are collected; according to the principle that the closer the determination coefficient is to 1, the closer the root mean square is to 0, and the scatter plot of the function, the mathematical model of the fixed angle and the stress, displacement of the mandible, and the stress and displacement of the titanium plate is obtained, the mid-perpendicular line of the wound is taken as the zero line, the zero line is defined as the positive direction toward the molar area, and the zero line is defined as the negative direction toward the mandibular bottom, the grid, load, and boundary conditions are controlled to be consistent, only the fixed position of the titanium plate is changed, a simulation experiment is performed every 1 mm from -9 to 9, and the stress and displacement of the mandible, and the stress and displacement of the titanium plate are also collected; according to the principle that the closer the determination coefficient is to 1, the closer the root mean square is to 0, and the scatter plot of the function, the mathematical model of the fixed angle position and the stress, displacement of the mandible, and the stress and displacement of the titanium plate is obtained.

2. The auxiliary assessment method for damaged mandible according to claim 1, characterized in that: In S1, a medical image CT device was used to collect CT images related to the mandible, which were grayscale images with a size of 604×640 and a layer thickness of 0.25 mm.

3. The auxiliary assessment method for damaged mandible according to claim 1, characterized in that: When a medical image CT device scans, it scans from the cervical spine to the upper eye socket and then saves the image in DICOM format.

4. The auxiliary assessment method for damaged mandible according to any one of claims 1 to 3, characterized in that: The specific method in S2 is as follows: import the CT image into the Mimics medical image processing platform, check that there are no errors in the horizontal, coronal and sagittal planes, generate the corresponding mask according to the bone threshold value pre-set by the software, extract the facial bones, and then use regional growing to remove the parts not connected to the mandible, and then use the mask editing tool to erase the remaining parts connected to the mandible, and finally generate the initial 3D model, which is imported into the reverse engineering processing platform Geomagic and enters the polygon processing stage, in which the triangular facets are optimized, spikes and redundant triangular faces are deleted, the surface of the model is smoothed, localized, and voids are repaired, and the triangular mesh quality can be improved. Requirements for constructing surface patches; after the triangular patch repair is completed, the surface mesh is divided. The model needs to be divided into blocks, and the surface is fitted into a rectangle based on the structural characteristics of the model. The corresponding feature boundaries are arranged on the model. After the feature boundaries are constructed, the surface of the constructed model will be divided into several parts, and the model will construct surface patches based on the constructed feature boundaries. The surface patches also need to be moved and added within the constructed feature boundaries to eventually achieve a regular surface patch structure. Finally, the fitted surfaces are merged and converted into a commonly used three-dimensional model format. Boolean operations are performed in the three-dimensional design software platform to construct cortical bone and cancellous bone, simulate various fractures, and add titanium plates to the model to simulate the fracture of the titanium plate and the model.

5. The auxiliary assessment method for damaged mandible according to claim 4, characterized in that: The specific method in S3 is as follows: the 3D model format is exported in X_T format in the 3D design software platform, and the X_T format is imported into the simulation calculation platform Abaqus. The material properties of titanium alloy, cortical bone, and cancellous bone are established. Flexible springs are used to replace the masseter, temporalis, lateral pterygoid, and medial pterygoid muscles required for mandibular movement. The size of the network is determined by successively reducing the mesh size and increasing the mesh density.

6. The auxiliary assessment method for damaged mandible according to claim 1, characterized in that: The variation law of mandibular stress y1 with the change of titanium plate fixation angle x is obtained: Where: k0, a i 、b i 、k i and γ i is the coefficient value obtained by fitting, x represents the fixed angle of the titanium plate, y1 represents the mandibular stress corresponding to a certain fixed angle x; As the titanium plate fixation angle x changes, the mandibular displacement y2 changes: Where: a i ′, b i ′,k i ′ and γ i ′ is the coefficient value obtained by fitting, x represents the fixed angle of the titanium plate, y2 represents the mandibular displacement corresponding to a certain fixed angle x, i = 1-4; As the fixed angle x of the titanium plate changes, the change law of the titanium plate stress y3 is: Where: k0″, a i ″, b i ″,k i ″ and γ i ″ is the coefficient value obtained by fitting, x represents the fixed angle of the titanium plate, y3 represents the stress value of the titanium plate corresponding to a certain fixed angle x, i = 1-4; As the fixed angle x of the titanium plate changes, the change law of the titanium plate displacement y4 is: Where: a i ″′,b i ″′,k i ″′ is the coefficient value obtained by fitting, x represents the fixed angle of the titanium plate, y4 represents the displacement of the titanium plate corresponding to a certain fixed angle x, and i=1-2.

7. The auxiliary assessment method for damaged mandible according to claim 1, characterized in that: As the titanium plate fixation position x1 changes, the change pattern of mandibular stress y5 is as follows: Where: and is the coefficient value obtained by fitting, x1 represents the fixed position of the titanium plate, and y5 represents the mandibular stress corresponding to a certain fixed position x1; As the titanium plate fixation position x1 changes, the mandibular displacement y6 changes: Where: and is the coefficient value obtained by fitting, i = 1-2, x1 represents the fixed position of the titanium plate, y7 represents the mandibular displacement corresponding to a certain fixed position 1; As the fixed position x1 of the titanium plate changes, the change law of the titanium plate stress y8 is: Where: and is the coefficient value obtained by fitting, x1 represents the fixed position of the titanium plate, y7 represents the stress of the titanium plate corresponding to a certain fixed position x1, and the change law of the titanium plate displacement y as the fixed position x1 of the titanium plate changes: Where: and is the coefficient value obtained by fitting, x1 represents the fixed position of the titanium plate, and y8 represents the displacement of the titanium plate corresponding to a fixed position x1.

8. An auxiliary assessment device for damaged mandible, characterized by: include, An image acquisition module, used for acquiring CT images of the damaged mandible; Mandibular fracture model construction module, which constructs a three-dimensional mandibular fracture model repaired with titanium plates and mandible based on CT images; The numerical analysis model construction module uses the simulation computing platform to construct a numerical analysis model based on the mandibular fracture model; A mathematical model construction module for the damaged mandible, which constructs a mathematical model of the titanium plate fixation position and angle after mandibular fracture repair based on the numerical analysis model and the data obtained from the numerical analysis model; The mathematical model construction method is as follows: the fracture site is defined as the fracture line, the fracture line is taken as the 0° line, the counterclockwise angle is the positive angle, the grid, load, and boundary conditions are controlled to be consistent, only the fixed angle of the titanium plate is changed, a simulation experiment is performed every 5°, and the stress and displacement of the mandible, and the stress and displacement of the titanium plate are collected; according to the principle that the closer the determination coefficient is to 1, the closer the root mean square is to 0, and the scatter plot of the function, the mathematical model of the fixed angle and the stress and displacement of the mandible, and the stress and displacement of the titanium plate is obtained, the median perpendicular line of the wound is taken as the zero line, the zero line is defined as the positive direction toward the molar area, and the zero line is defined as the negative direction toward the mandibular bottom, the grid, load, and boundary conditions are controlled to be consistent, only the fixed position of the titanium plate is changed, a simulation experiment is performed every 1 mm from -9 to 9, and the stress and displacement of the mandible, and the stress and displacement of the titanium plate are also collected; according to the principle that the closer the determination coefficient is to 1, the closer the root mean square is to 0, and the scatter plot of the function, the mathematical model of the fixed angle position and the stress and displacement of the mandible, and the stress and displacement of the titanium plate is obtained; Evaluation module: Based on the corresponding function relationship of the mathematical model, it is mapped into the relationship between color partitions and the corresponding titanium plate fixation position and angle, and the quality of mandibular fracture repair is evaluated through color partitions.

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