Three-dimensional space displacement loading method for active contraction and relaxation of female pelvic floor levator ani muscle

Abstract

The invention discloses a three-dimensional space displacement loading method for active contraction and relaxation of female pelvic floor levator ani muscles, and belongs to the field of medical imaging technology, female pelvic floor medicine and biomechanics research. The method comprises the following steps: acquiring MRI (Magnetic Resonance Imaging) images of the same woman in resting, Valsalva and anal contraction states, and correcting the position of the levator ani muscle under the three-state MRI images by utilizing medical image software Mimics; on the basis of the calibrated three-state MRI image, position characteristic parameters of the levator ani muscle in a three-dimensional space are obtained, and the form displacement difference among the three states is calculated. A pelvic floor three-dimensional finite element model in a resting state is constructed, a levator ani muscle bearing surface node set is divided, and biomechanical characteristics of levator ani muscles in different functional states can be quantitatively analyzed by applying a three-dimensional space displacement load to the levator ani muscle surface node set. According to the method, imaging and biomechanics are combined, and three-dimensional space dynamic mechanical characterization of the active contraction and relaxation functional state of pelvic floor muscles is achieved.

Description

Technical Field

[0001] The present invention relates to a three-dimensional spatial displacement load method for active contraction and relaxation of the female pelvic floor levator ani muscles, and belongs to the research fields of medical imaging technology, female pelvic floor medicine and biomechanics. Background Art

[0002] Pelvic floor dysfunction (PFD), such as urinary incontinence and pelvic organ prolapse, severely impacts women's quality of life, with incidence increasing significantly with age. Studying the biomechanical properties of the levator ani muscles, a core muscle group that maintains pelvic floor stability, in both contracted and relaxed states is crucial for understanding the pathogenesis of PFD and optimizing treatment options.

[0003] Existing research on the mechanical properties of the levator ani muscle faces significant limitations. Currently, there are no mechanical modeling methods for its active contraction and relaxation. Regarding detection methods, while traditional ultrasound imaging offers real-time capabilities, its resolution is low, making it difficult to accurately capture subtle morphological changes in the levator ani muscle. While magnetic resonance imaging (MRI) can provide high-resolution images, existing methods are mostly limited to static structural analysis, lacking systematic research on the active dynamic behavior and dynamic changes of the levator ani muscle in different functional states (such as resting, Valsalva maneuver, and anal contraction). Regarding mechanical analysis, most studies rely on empirical formulas or simplified models, failing to fully consider individual differences and the nonlinear mechanical behavior of the muscle in multiple states, resulting in discrepancies between biomechanical analysis results and actual physiological conditions. Furthermore, existing finite element simulation methods often employ preset fixed parameters in the two-dimensional sagittal plane during load application, making it impossible to achieve personalized three-dimensional spatial modeling and accurate analysis based on real physiological data. In summary, existing technologies struggle to meet the demand for high-precision, dynamic, and personalized analysis of the three-dimensional morphological changes and biomechanical properties of the active contraction and relaxation of the female pelvic floor levator ani muscle. Summary of the Invention

[0004] This invention aims to investigate the three-dimensional biomechanical properties of the female pelvic floor levator ani muscle during its evolution from resting state to active contraction and relaxation. It innovatively proposes a loading method for the three-dimensional morphological changes of the levator ani muscle during active contraction and relaxation. By establishing a standardized calibration system based on resting-state MRI images, the method accurately corrects for three-dimensional image deviations caused by changes in body position during functional states such as Valsalva and ani contraction, effectively eliminating measurement errors caused by positional changes and significantly improving the consistency and reliability of multi-state imaging data. This enhances the scientific and rigorous nature of biomechanical analysis results and lays a solid data foundation for in-depth exploration of the physiological and mechanical mechanisms of the levator ani muscle. Conventional biomechanical analysis methods for the female pelvic floor levator ani muscle often use simplified models or empirical parameters for load simulation, failing to accurately reflect the active dynamic characteristics of the levator ani muscle during its true physiological states, including resting, active contraction, and relaxation. The existing art lacks a systematic study of the quantitative relationship between the morphological changes and mechanical responses of the levator ani muscle during multiple active contraction and relaxation states, making it difficult for the analysis results to effectively guide the clinical diagnosis and treatment of pelvic floor dysfunction (PFD). The present invention aims to overcome the aforementioned technical deficiencies by providing a three-dimensional spatial displacement load method for the active contraction and relaxation of the female pelvic floor levator ani muscles based on multi-state MRI imaging data. By precisely measuring the three-dimensional spatial morphological and positional characteristics of the levator ani muscles in different functional states, conducting in-depth analysis of morphological variations, and constructing a three-dimensional spatial displacement value consistent with physiological characteristics, this method achieves high-precision quantitative analysis of the three-dimensional spatial morphological changes and biomechanical properties of the active contraction and relaxation of the levator ani muscles, providing reliable technical support for the study of the pathogenesis, clinical diagnosis, and optimization of treatment options for PFD.

[0005] The technical solution adopted by the present invention is: a three-dimensional spatial displacement load method for active contraction and relaxation of the female pelvic floor levator ani muscles, characterized by the following steps:

[0006] Step 1: Using magnetic resonance imaging technology, high-precision MRI images are obtained for the same woman at rest, in Valsalva position, and with the bladder kept consistently full over the same period of time.

[0007] Step 2: Based on the MRI images obtained in step 1 at rest, Valsalva, and anal contraction, the medical imaging software Mimics was used to manually correct the deviations in the Valsalva and anal contraction images due to changes in body position using the resting-state image as a reference. The software's image analysis tool was then used to depict the morphological contours of the levator ani muscles in the three states on the sagittal plane of the MRI images.

[0008] Step 3: In the medical imaging software Mimics, select sagittal 2D images corresponding to the resting state, Valsalva state, and anal contraction state. Combined with the calibrated horizontal and vertical reference lines, use measurement tools to obtain the spatial position characteristic parameters of the levator ani muscle in the three states. Based on the obtained parameters, further analyze the morphological changes between different states to construct the load-bearing surface node set displacement of the levator ani muscle mechanical characteristics.

[0009] Step 4: Using the resting-state MRI image acquired in Step 1, the medical imaging modeling software Mimics is used as the data source. Image segmentation and feature extraction techniques are used to obtain the contour data of each organ in the pelvic floor support system. This data set is then imported into professional 3D modeling software. Surface reconstruction and solid modeling are performed based on the vectorized contour information to complete the construction of the 3D geometric models of each pelvic floor organ.

[0010] Step 5: Based on the three-dimensional geometric models of the pelvic floor organs obtained in step 4, professional ABAQUS finite element software is used to construct a high-precision three-dimensional pelvic floor finite element model through meshing, material property assignment, and boundary condition setting operations. The displacement of the load-bearing surface node set constructed in step 3 is applied to the levator ani muscle model. Through finite element simulation technology, the displacement load of the levator ani muscle in different functional states of rest, Valsalva, and anal contraction is simulated, and the distribution law of stress, strain, and displacement mechanical parameters is systematically calculated and analyzed.

[0011] The specific steps of step 2 are:

[0012] 2.1) The horizontal and vertical axes of the three MRI images were corrected using the medical imaging software Mimics. In the resting midsagittal MRI image, the software's measurement tools were used to connect the distal end of the third-to-last segment of the sacrum and the inferior pubic border, and the distance between the two points was measured. A horizontal line was drawn through the inferior pubic border, and the angle between the horizontal line and the line connecting the distal end of the third-to-last segment of the sacrum and the inferior pubic border was measured. A perpendicular line was drawn through the distal end of the third-to-last segment of the sacrum and measured, and the distance between the inferior pubic border and the intersection of the horizontal and vertical lines was measured. Furthermore, the distance between the distal end of the third-to-last segment of the sacrum and the intersection of the horizontal and vertical lines was measured.

[0013] 2.2) Using the resting-state MRI images as a reference, the Valsalva and anal contraction images were corrected. In the midsagittal plane images of both functional states, a marker tool was used to connect the end point of the third-to-last segment of the sacrum and the lower edge of the pubic bone to form a baseline. Subsequently, using the lower edge of the pubic bone as the apex and the baseline as the fixed edge, image measurement software was used to maintain the same angular parameters as those in the resting state to generate a calibrated horizontal reference line. A perpendicular line was then drawn through the end point of the third-to-last segment of the sacrum and coccyx to complete the standardization correction.

[0014] 2.3) Using the medical imaging modeling software Mimics, the morphology of the levator ani muscle in three states was depicted based on the sagittal plane of the MRI image.

[0015] The specific steps of step 3 are:

[0016] In the medical imaging software Mimics, the vertical line in the midsagittal plane of the resting state and the calibrated Valsalva state and anus contraction state MRI images was divided into n parts, corresponding to n + 1 equal division points. A vertical line was drawn through the equal division points, and the distance from each equal division point to the lateral side of the levator ani muscle was measured using the measurement tool in the software. Then, with the midsagittal plane as the center, symmetrically distributed sagittal planes were selected on both sides, and the same calibration and measurement methods were used to obtain the spatial position characteristic parameters of the levator ani muscle. The distance measured in the resting state was recorded as y rn The distance measured in the Valsalva state and the anal contraction state is recorded as y sn , and the displacement of the node set on the levator ani muscle bearing surface is obtained as follows:

[0017] u yn =y sn -y rn

[0018] Adding an error correction term to the formula, the corrected formula is:

[0019] U yn =(y sn -y rn )·(1±σ)

[0020] Among them U yn is the correction displacement, and σ is the sample standard deviation.

[0021] Preferably, the professional 3D modeling software in step 4 is Soildworks.

[0022] The specific steps of step 5 are:

[0023] 5.1) In the ABAQUS finite element software, the resting levator ani muscle finite element model was split using the datum plane splitting technique. The perpendicular line in the midsagittal plane was divided into n equal parts, and the corresponding levator ani muscle was also divided into n parts. A datum plane in the ZY plane was constructed based on the X direction of the midsagittal plane. Then, symmetrical datum planes were established on the left and right sides with the midsagittal plane as the center. The model was split along the datum plane using the software's splitting tool. Similarly, a group of datum planes with equal spacing was established in the XY plane based on the spacing of the equal-dividing points in the Z axis. Through multiple split operations, the levator ani muscle was divided into n transverse sections in the Z axis direction. The intersection nodes formed by the ZY datum plane and the XY datum plane during the model splitting process were defined as the load-bearing point set on the levator ani muscle surface.

[0024] 5.2) In the load module of the ABAQUS finite element software, displacement loads were applied to the surface load points of the levator ani muscle, assigning corresponding displacements point by point. This enabled a quantitative analysis of the biomechanical properties of the levator ani muscle in different functional states: resting, contracted, and Valsalva.

[0025] The beneficial effects of the present invention are:

[0026] (1) The present invention takes the female pelvic floor levator ani muscle as the research object, focusing on its morphological position characteristics and biomechanical properties in three states: resting, Valsalva and anal contraction. High-precision images in different states are obtained by magnetic resonance imaging technology. Medical image processing, data analysis and finite element simulation are used to deeply study the morphological changes of the levator ani muscle in different functional states, and displacement is constructed for biomechanical analysis, aiming to provide scientific basis and technical support for the diagnosis and treatment of female pelvic floor dysfunction diseases.

[0027] (2) The present invention proposes a method for calibrating magnetic resonance images. By establishing a standardized correction system based on resting MRII images, the image spatial deviation caused by changes in human body position in functional states such as Valsalva maneuver state and anal contraction maneuver state can be accurately corrected, and the measurement error caused by position change can be effectively eliminated. The consistency and reliability of multi-state imaging data can be significantly improved, thereby enhancing the scientificity and rigor of the biomechanical analysis results and laying a solid data foundation for in-depth exploration of the physiological and mechanical mechanism of the levator ani muscle.

[0028] (3) The present invention provides a displacement load method for the female pelvic floor levator ani muscle based on MRI multi-state imaging data. By accurately measuring the morphological and positional characteristics of the levator ani muscle in different functional states, in-depth analysis of the morphological changes, and constructing a displacement value that conforms to physiological characteristics, high-precision quantitative analysis of the biomechanical properties of the levator ani muscle is achieved, providing reliable technical support for the study of the pathogenesis of PFD, clinical diagnosis, and optimization of treatment plans. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart for implementing the present invention;

[0030] Figure 2 It is the baseline image of the midsagittal plane at rest;

[0031] Figure 3 Figure 1 is a correction diagram of the midsagittal plane in the Valsalva state and the anus contraction state, wherein Figure (a) is a correction diagram of the midsagittal plane in the Valsalva state, and Figure (b) is a correction diagram of the midsagittal plane in the anus contraction state;

[0032] Figure 4It is the characteristic parameter diagram of the levator ani muscle position in the sagittal plane;

[0033] Figures a, b, and c are the position parameter diagrams of the levator ani muscles in the median sagittal plane at rest, alsalva, and anal contraction, respectively; with the median sagittal plane as the center, symmetrically distributed sagittal planes are selected to the left and right sides, with a distance of 5 mm between each two sagittal planes; Figures a1, b1, and c1 are the position parameter diagrams of the levator ani muscles in the right sagittal plane 5 mm away from the median sagittal plane, respectively, in the rest, alsalva, and anal contraction states; Figures a2, b2, and c2 are the position parameter diagrams of the levator ani muscles in the median sagittal plane 5 mm away from the median sagittal plane, respectively. Figures a3, b3, and c3 are positional characteristic parameter diagrams of the levator ani muscle at the right sagittal plane at a distance of 10 mm from the midsagittal plane in the resting state, alsalva state, and anal contraction state, respectively; Figures a4, b4, and c4 are positional characteristic parameter diagrams of the levator ani muscle at the left sagittal plane at a distance of 10 mm from the midsagittal plane in the resting state, alsalva state, and anal contraction state, respectively;

[0034] Figure 5 It is a three-dimensional solid geometric model at rest;

[0035] Figure 6 The left side shows the corresponding displacement of the levator ani muscle surface load-bearing point set in the anal contraction state and the Valsalva state, and the right side shows the corresponding displacement of the levator ani muscle surface load-bearing point set in the Valsalva state.

[0036] Figure 7 This is the displacement result diagram of the resting state simulation Valsalva state and anal contraction state;

[0037] in: Figure 7 The upper and lower rows on the left side respectively represent the overall displacement cloud map and the displacement cloud map of the levator ani muscle in the resting state simulated Valsalva state, and the upper and lower rows on the right side respectively represent the overall displacement cloud map and the displacement cloud map of the levator ani muscle in the anal contraction state. DETAILED DESCRIPTION

[0038] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Example 1: Figure 1-7 As shown, a three-dimensional spatial displacement load method for active contraction and relaxation of the female pelvic floor levator ani muscles is as follows:

[0040] Step 1: Select a female volunteer without pelvic floor dysfunction and obtain signed informed consent prior to the examination. Before scanning with MRI technology, the subject will be required to practice the Valsalva and anal contraction maneuvers to ensure the accuracy of the scan results. MRI images are acquired using an MRI scanner while the subject lies supine, with the bladder consistently filled, in the resting state, the Valsalva maneuver, and the anal contraction maneuver over the same period of time. The field of view is 20 cm × 20 cm, with a slice thickness of 1 mm.

[0041] Step 2: Using the medical imaging software Mimics, with the resting-state image as the spatial reference, we manually corrected for spatial deviations in the Valsalva and anal contraction images due to changes in body position by referencing the angle between the line connecting the third-to-last segment of the sacrum and the lower edge of the pubic bone in the midsagittal plane of the resting-state MRI image and the horizontal line and the vertical line. Using the image segmentation function of the software, we delineated the contours of the levator ani muscles in each of the three states layer by layer along the sagittal plane of the MRI image.

[0042] The specific steps are:

[0043] 2.1) Using the medical imaging software Mimics, in a resting midsagittal MRI image, the measurement tool of the software was used to connect the end point of the third last segment of the sacrum and the lower edge of the pubic bone (ab line), and the distance between the two points was measured to be 97 mm; a horizontal line was drawn through the lower edge of the pubic bone, and the angle between the horizontal line and the ab line was measured to be 31.75°; a perpendicular line was drawn through the end point of the third last segment of the sacrum and the lower edge of the pubic bone and the intersection of the horizontal and vertical lines, and the distance between the end point of the third last segment of the sacrum and the intersection of the horizontal and vertical lines was measured to be 83 mm; and the distance between the end point of the third last segment of the sacrum and the intersection of the horizontal and vertical lines was measured to be 51 mm ( Figure 2 ).

[0044] 2.2) In the medical imaging software Mimics, manual calibration of the Valsalva and anal contraction images was performed using the resting MRII images as a reference. First, in the midsagittal MRII images of the Valsalva and anal contraction states, the software's measurement tool was used to connect the end point a of the third segment from the sacrum and coccyx with the point b at the lower edge of the pubic bone to form the ab reference line. Subsequently, the image measurement tool was used to maintain the same angle parameters as the resting state, generating a calibrated bc horizontal reference line. Furthermore, a vertical line ac was drawn from the end point a of the third segment from the sacrum and coccyx, ultimately completing the standardized calibration of the Valsalva and anal contraction state images. Figure 3 ).

[0045] 2.3) In the medical imaging modeling software Mimics, the manually calibrated auxiliary lines were hidden, leaving only the calibrated vertical line ac. The morphology of the levator ani muscle in the three states was depicted based on the midsagittal plane of the MRI image.

[0046] Step 3: Using the medical imaging software Mimics, we selected midsagittal 2D images corresponding to the resting, Valsalva, and contracted states. Combined with the calibrated vertical reference lines, we used image segmentation and feature extraction techniques to obtain the spatial positional characteristic parameters of the levator ani muscle in each of the three states. Based on these parameters, we further analyzed the morphological changes between the different states and constructed the displacement of the load-bearing surface node set that represents the mechanical properties of the levator ani muscle.

[0047] The specific steps are:

[0048] In the medical imaging software Mimics, the vertical line in the midsagittal plane of the resting state and the calibrated Valsalva state and anus contraction state MRII images was divided into 10 equal parts, corresponding to 11 equal points. A vertical line was drawn through the equal points. The distance from each equal point to the lateral side of the levator ani muscle was measured using the measurement tool in the software. Then, with the midsagittal plane as the center, symmetrically distributed sagittal planes were selected on both sides. The distance between each two sagittal planes was 5 mm. The spatial position characteristic parameters of the levator ani muscle ( Figure 4 ); the distance measured in the resting state is recorded as y rn The distance measured in the Valsalva state and the anal contraction state is recorded as y sn , and the displacement of the node set on the levator ani muscle bearing surface is obtained as follows: u yn =y sn -y rn

[0049] Through statistical analysis of more samples, an error correction term can be added to the formula. The corrected formula is:

[0050] U yn =(y sn -y rn )·(1±σ)

[0051] Among them U yn is the correction displacement, and σ is the sample standard deviation.

[0052] Step 4: Using the resting-state MRI images acquired in Step 1, the medical imaging modeling software Mimics is used as the data source. Image segmentation and feature extraction techniques are then used to obtain a contour dataset of the organs in the pelvic floor support system. Subsequently, the extracted dataset is imported into professional 3D modeling software (in this example, Soildworks). Surface reconstruction and solid modeling are performed based on the vectorized contour information to complete the construction of a 3D geometric model of the pelvic floor organs.

[0053] Step 5: Based on the three-dimensional geometric model of the pelvic floor organs obtained in step 4, use ABAQUS finite element software to import the three-dimensional geometric model of the female pelvic floor support system in the resting state (such as Figure 5 ) A high-precision three-dimensional finite element model of the pelvic floor was constructed through meshing, assigning material properties, and setting boundary conditions. The displacement of the load-bearing surface node set constructed in Step 3 was applied to the levator ani muscle model. Finite element simulation technology was used to simulate the displacement load of the levator ani muscle in different functional states, including resting, Valsalva maneuver, and anal contraction. The distribution patterns of mechanical parameters such as stress, strain, and displacement were systematically calculated and analyzed.

[0054] The specific steps are:

[0055] 5.1) In the ABAQUS finite element software, the resting levator ani muscle finite element model was split using the datum plane splitting technique. The perpendicular line in the midsagittal plane was divided into 10 equal parts, and the corresponding levator ani muscle was also divided into 10 parts. The ZY plane datum plane was constructed based on the X coordinate of the midsagittal plane. Then, four symmetrically distributed datum planes were established on the left and right sides of the midsagittal plane datum plane as the center. The model was divided along the datum plane using the software's splitting tool. Similarly, based on the spacing of the equal-dividing points in the Z-axis direction, a group of datum planes with equal spacing was established in the XY plane. Through multiple split operations, the levator ani muscle was divided into 10 transverse sections in the Z-axis direction. The intersection nodes formed by the ZY datum plane and the XY datum plane during the model splitting process were defined as the load-bearing point set on the levator ani muscle surface.

[0056] 5.2) In the load module of ABAQUS finite element software, the displacement calculated by the formula is applied to the corresponding load point set on the surface of the levator ani muscle ( Figure 6 ), to achieve quantitative analysis of the biomechanical characteristics of the levator ani muscle in different functional states such as resting state, anal contraction state and Valsalva state, and to analyze the distribution law of mechanical parameters such as stress and displacement ( Figure 7 ).

[0057] This method uses magnetic resonance imaging (MRI) technology to obtain the morphological parameters of the female pelvic floor levator ani muscles in three states: resting, actively contracted, and actively relaxed. Combined with ABAQUS finite element analysis software, it constructs the displacement of the levator ani muscle's load-bearing surface, enabling quantitative analysis of the levator ani muscle's biomechanical properties under different functional loads, including resting, Valsalva, and contracted loads. This technology, integrating multidisciplinary techniques such as medical imaging data processing, biomechanical modeling, and finite element simulation, provides innovative technical means for studying the pathogenesis, clinical diagnosis, and optimizing treatment options for female pelvic floor dysfunction.

[0058] The above describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A three-dimensional spatial displacement load method for active contraction and relaxation of the female pelvic floor levator ani muscles, characterized in that :The steps are as follows: Step 1: Using magnetic resonance imaging technology, high-precision MRI images are obtained for the same woman at rest, in Valsalva position, and with the bladder kept consistently full over the same period of time. Step 2: Based on the MRI images obtained in step 1 at rest, Valsalva, and anal contraction, the medical imaging software Mimics was used to manually correct the deviations in the Valsalva and anal contraction images due to changes in body position using the resting-state image as a reference. The software's image analysis tool was then used to depict the morphological contours of the levator ani muscles in the three states on the sagittal plane of the MRI images. Step 3: In the medical imaging software Mimics, select sagittal 2D images corresponding to the resting state, Valsalva state, and anal contraction state. Combined with the calibrated horizontal and vertical reference lines, use measurement tools to obtain the spatial position characteristic parameters of the levator ani muscle in the three states. Based on the obtained parameters, further analyze the morphological changes between different states to construct the load-bearing surface node set displacement of the levator ani muscle mechanical characteristics. Step 4: Using the resting-state MRI image acquired in Step 1, the medical imaging modeling software Mimics is used as the data source. Image segmentation and feature extraction techniques are used to obtain the contour data of each organ in the pelvic floor support system. This data set is then imported into professional 3D modeling software. Surface reconstruction and solid modeling are performed based on the vectorized contour information to complete the construction of the 3D geometric models of each pelvic floor organ. Step 5: Based on the three-dimensional geometric models of the pelvic floor organs obtained in step 4, professional ABAQUS finite element software is used to construct a high-precision three-dimensional pelvic floor finite element model through meshing, material property assignment, and boundary condition setting operations. The displacement of the load-bearing surface node set constructed in step 3 is applied to the levator ani muscle model. Through finite element simulation technology, the displacement load of the levator ani muscle in different functional states of rest, Valsalva, and anal contraction is simulated, and the distribution law of stress, strain, and displacement mechanical parameters is systematically calculated and analyzed.

2. A three-dimensional displacement load method for active contraction and relaxation of the female pelvic floor levator ani muscles according to claim 1, characterized in that :The specific steps of step 2 are: 2.1) The horizontal and vertical axes of the three MRI images were corrected using the medical imaging software Mimics. In the resting midsagittal MRI image, the software's measurement tools were used to connect the distal end of the third-to-last segment of the sacrum and the inferior pubic border, and the distance between the two points was measured. A horizontal line was drawn through the inferior pubic border, and the angle between the horizontal line and the line connecting the distal end of the third-to-last segment of the sacrum and the inferior pubic border was measured. A perpendicular line was drawn through the distal end of the third-to-last segment of the sacrum and measured, and the distance between the inferior pubic border and the intersection of the horizontal and vertical lines was measured. 2.2) Using the resting-state MRI images as a reference, the Valsalva and anal contraction images were calibrated. In the midsagittal plane images of both functional states, a marker tool was used to connect the end point of the third-to-last segment of the sacrum and the lower edge of the pubic bone to form a baseline. Subsequently, using the lower edge of the pubic bone as the vertices and the baseline as the fixed edge, image measurement software was used to maintain the same angle parameters as the resting state to generate a calibrated horizontal reference line. A perpendicular line was then drawn through the end point of the third-to-last segment of the sacrum to complete the standardization calibration. 2.3) Using the medical imaging modeling software Mimics, the morphology of the levator ani muscle in three states was depicted based on the sagittal plane of the MRI image.

3. A three-dimensional spatial displacement load method for active contraction and relaxation of the female pelvic floor levator ani muscles according to claim 1, characterized in that :The specific steps of step 3 are: In the medical imaging software Mimics, the vertical line in the midsagittal plane of the resting state and the calibrated Valsalva state and anus contraction state MRI images was divided into n parts, corresponding to n + 1 equal division points. A vertical line was drawn through the equal division points, and the distance from each equal division point to the lateral side of the levator ani muscle was measured using the measurement tool in the software. Then, with the midsagittal plane as the center, symmetrically distributed sagittal planes were selected on both sides, and the same calibration and measurement methods were used to obtain the spatial position characteristic parameters of the levator ani muscle. The distance measured in the resting state was recorded as y rn The distance measured in the Valsalva state and the anal contraction state is recorded as y sn , and the displacement of the node set on the levator ani muscle bearing surface is obtained as follows: or yn =and sn -and rn Adding an error correction term to the formula, the corrected formula is: OR yn =(and sn -and rn )·(1±σ) Among them U yn is the correction displacement, and σ is the sample standard deviation.

4. A three-dimensional displacement load method for active contraction and relaxation of the female pelvic floor levator ani muscles according to claim 1, characterized in that :The professional 3D modeling software in step 4 is Soildworks.

5. A three-dimensional spatial displacement load method for active contraction and relaxation of the female pelvic floor levator ani muscles according to claim 1, characterized in that :The specific steps of step 5 are: 5.1) In the ABAQUS finite element software, the resting levator ani muscle finite element model was split using the datum plane splitting technique. The perpendicular line in the midsagittal plane was divided into n parts, and the corresponding levator ani muscle was also divided into n parts. A datum plane in the ZY plane was constructed based on the X direction of the midsagittal plane. Then, symmetrically distributed datum planes were established on the left and right sides with the midsagittal plane as the center. The model was split along the datum plane using the software's splitting tool. Similarly, based on the spacing of the equal-division points in the Z-axis direction, a group of equidistant datum planes was established in the XY plane. Through multiple split operations, the levator ani muscle was divided into n transverse partitions in the Z-axis direction. The intersection nodes formed by the ZY datum plane and the XY datum plane during the model splitting process were defined as the load-bearing point set on the levator ani muscle surface. 5.2) In the load module of the ABAQUS finite element software, displacement loads were applied to the surface load points of the levator ani muscle, assigning corresponding displacements point by point. This enabled a quantitative analysis of the biomechanical properties of the levator ani muscle in different functional states: resting, contracted, and Valsalva.

Images