Method for simulating prolapse pelvic floor suspension reconstruction operation and evaluating sagittal plane
The high recurrence rate and lack of biomechanical evaluation of existing surgery are solved by simulating and evaluating the mechanical effects of suspension reconstruction surgery using 3.0T high-field strong magnetic resonance imaging and finite element analysis methods in prolapsed pelvic floor surgery. , achieving more accurate surgical effectiveness evaluation and improvement, reducing recurrence rate.
Patent Information
- Application Number
- CN202411484376.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-22
- Publication Date
- 2025-02-14
AI Technical Summary
Existing suspension reconstruction surgery has high recurrence rates and complications in the treatment of prolapsed pelvic floor, and the lack of effective biomechanical evaluation methods, making it difficult to evaluate and improve the surgical effect.
A surgical simulation and sagittal plane evaluation method for prolapsed pelvic floor suspension reconstruction was proposed. Through 3.0T high-field strong magnetic resonance imaging and finite element analysis, an accurate geometric model and mechanical model of pelvic floor prolapse are established. , simulate the mechanical effects of different suspension reconstruction surgery and surgical mesh, evaluate the surgical effect and predict possible postoperative complications.
This method can more accurately simulate and evaluate the surgical effect of prolapsed pelvic floor, provide biomechanical design basis, help improve surgical plans, reduce recurrence rates, and provide new directions and theoretical basis for the study of POP occurrence mechanism and clinical treatment.
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Figure CN119423979A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of suspension reconstruction surgery simulation, surgery effect evaluation method and biomechanics research of prolapsed pelvic floor. It mainly studies the effect and influence of suspension reconstruction surgery on pelvic floor biomechanical repair after suspension reconstruction surgery simulation of prolapsed pelvic floor, specifically, it is a suspension reconstruction surgery simulation and sagittal plane evaluation method of prolapsed pelvic floor. Background Art
[0002] Pelvic organ prolapse refers to the downward displacement of female pelvic organs (such as bladder, uterus and rectum), which causes the vagina, uterus or both to protrude from the pelvic cavity. It is more common in middle-aged and elderly women with a prevalence rate as high as 41.1%, while the surgical treatment rate is 10-20%. One-third of women will undergo multiple surgeries due to recurrence of pelvic organ prolapse. This has seriously affected the physical and mental health and quality of life of middle-aged and elderly women.
[0003] At present, the top suspension surgery established under the guidance of the "three-level theory" and the "three-chamber theory" still has a high rate of complications and recurrence. For example, 29% of women with hysteropexy had recurrence of uterine prolapse, and 54% of women with hysterectomy had recurrence of uterine prolapse, and the vaginal angle and position were related to the recurrence of prolapse. From the fundamental reason, these theories basically explore the pathogenesis of POP from the histomorphology of female pelvic floor anatomy and the pathophysiology of POP, thus ignoring the mutual support function between the soft tissues of the pelvic floor organs and the biomechanical relationship of ligament fascia suspension support and the principle of overall biomechanical balance mechanism. Studies have found that multi-structural damage to the pelvic floor during the pathological process is an important cause of the destruction of the mechanical balance state of the pelvic floor and POP. At present, the mechanical reconstruction effects of different suspension reconstruction surgeries and surgical meshes cannot be effectively evaluated from the perspective of pelvic floor biomechanics, and the design and improvement of preoperative surgery and surgical meshes for prolapsed pelvic floor lack the basis for pelvic floor biomechanical design. At the same time, since the therapeutic effects of pelvic floor reconstruction surgery are generally based on statistics and analysis of clinical data, little attention is paid to the biomechanical effects of pelvic floor reconstruction surgery, surgical mesh and organ tissues, and there are problems such as high recurrence rate. Therefore, there is an urgent need for simulation and sagittal plane evaluation methods of prolapse pelvic floor suspension reconstruction surgery. Summary of the invention
[0004] The present invention proposes a method for simulating the suspension reconstruction surgery of the prolapsed pelvic floor, evaluating the surgical effect and biomechanical research, providing biomechanical suggestions for the selection, design and improvement of surgical plans, and further guiding the surgery and optimizing the clinical treatment plan. This method can be used for the biomechanical research, surgical simulation and effect evaluation of the prolapsed pelvic floor of clinical patients before surgery, and provides support and improvement space for the study of physiological mechanical reconstruction surgery and treatment of the prolapsed pelvic floor.
[0005] This method is suitable for simulation, evaluation and biomechanical analysis of suspension reconstruction surgery for different age groups, different degrees of pelvic organ prolapse and different types of prolapsed pelvic floor. It can simulate the suspension reconstruction surgery of prolapsed pelvic floor under different abdominal pressures, tissue and organ damage and reproductive fissures, evaluate the surgical effect, and study the changes in pelvic floor biomechanics after surgery. It provides a theoretical basis and prediction for clinical phenomena, clinical diagnosis results and treatment, helps us understand the pathogenesis of POP, and has important guiding significance for proposing new directions and theoretical basis support for the treatment and suspension reconstruction of female pathological pelvic floor prolapse.
[0006] The technical solution adopted by the present invention is: a method for simulating and evaluating sagittal plane of a prolapsed pelvic floor suspension reconstruction surgery, and the implementation steps are as follows:
[0007] Step 1: Use 3.0T high-field magnetic resonance imaging to perform midsagittal imaging of different age groups, different degrees of pelvic organ prolapse, and different types of prolapsed pelvic floor in clinical practice. Based on MRI technology and imaging analysis data, combined with computer-aided design software, the organs supported by the pelvic floor are accurately reconstructed to obtain a two-dimensional sagittal prolapse geometric model of the pelvic floor with pathological shape and position characteristics.
[0008] Step 2: Using finite element software, an accurate two-dimensional finite element model of the female prolapsed pelvic floor with pathological shape and position characteristics in the sagittal plane is established based on the two-dimensional sagittal plane prolapse geometric model of the pelvic floor with pathological shape and position characteristics obtained in step 1.
[0009] Step 3: Select different types of surgical meshes according to different suspension reconstruction surgeries, and obtain the specific material performance parameters of the surgical mesh through mesh mechanical experiments or test reports.
[0010] Step 4: According to the selected suspension reconstruction surgery and surgical mesh type, determine the starting and ending positions of the surgical mesh suture in the female pelvic floor, and use Hooke's law and the combined force method to construct the mechanical projection relationship of different suspension reconstruction surgeries and surgical meshes on the sagittal plane of the prolapsed pelvic floor. Calculate the equivalent stiffness mechanical parameters of the surgical mesh, and use an evenly distributed damping spring to simulate the equivalent mechanical properties of the surgical mesh, and construct the equivalent mechanical model of the prolapsed pelvic floor sagittal plane of different types of suspension reconstruction surgery and surgical meshes.
[0011] Step 5: Perform finite element simulation analysis on the sagittal equivalent mechanical model of the prolapsed pelvic floor obtained in step 4. The effects of suspension reconstruction surgery and surgical mesh were evaluated by the sagittal plane evaluation method after prolapsed pelvic floor surgery, and the changes in postoperative pelvic floor biomechanics and their effects on prolapsed pelvic floor were analyzed and discussed.
[0012] Specifically, the specific method operation steps according to step 4 are:
[0013] 4.1) Select the type of suspension reconstruction surgery and determine the type of surgical mesh to be used for the surgery.
[0014] 4.2) Determine the starting and ending points of the surgical mesh suture in the female pelvic floor. For uterosacral suspension, the equivalent positions of the surgical mesh are D0 (no mesh suspension), D1 (suspension at the front edge of sacral 1), D2 (suspension at the front edge of sacral 2), D3 (suspension at the front edge of sacral 3), D4 (suspension at the front edge of sacral 4), and D5 (suspension at the front edge of sacral 5).
[0015] 4.3) The three-dimensional mechanical action of the surgical mesh in the pelvic floor is equivalently calculated on the median sagittal plane, and the combined mechanical action of the surgical mesh on the median sagittal plane is calculated.
[0016] 4.4) According to Hooke's law and the principle of mechanical equilibrium, the formula F = -2 × K × cos (θ / 2) × a is used to obtain the resultant force of the surgical mesh in the midsagittal plane. (Where F is the tensile load on the surgical mesh (N); the negative sign indicates that the elastic force generated by the equivalent spring of the surgical mesh is opposite to its elongation direction; K is the stiffness of the surgical mesh (N / mm); θ is twice the projected angle between a single surgical mesh and the midsagittal plane (°); a is the elastic deformation or tensile displacement (mm)).
[0017] 4.5) Using formula K w =n×b and b=L1×L2, and the proportional coefficient K of the equivalent damping spring stiffness parameter of the surgical mesh is obtained. w . (Where b is the size ratio coefficient; n is the number of spring units with approximately even distribution of equivalent action; surgical mesh L1 is the equivalent width of each pelvic organ; L2 is the average width of each pelvic organ).
[0018] 4.6) From 4.4) and 4.5), the equivalent mechanical effect of the surgical mesh in the midsagittal plane is F d =F / K w (where F d for the equivalent effectiveness of surgical mesh).
[0019] 4.7) From the above formulas, the equivalent stiffness K of the surgical mesh can be obtained: d , expressed as:
[0020] Specifically, the specific method operation steps according to step 5 are:
[0021] 5.1) The results of simulating the surgical mesh in the equivalent position under the action of abdominal pressure. For uterine sacral suspension, the results of simulating the surgical mesh in the equivalent position are D0 (no mesh suspension), D1 (suspension at the front edge of sacral 1), D2 (suspension at the front edge of sacral 2), D3 (suspension at the front edge of sacral 3), D4 (suspension at the front edge of sacral 4), and D5 (suspension at the front edge of sacral 5).
[0022] 5.2) Evaluate the biomechanical repair effect of the surgical mesh at the equivalent position: Under the action of the surgical mesh, the evaluation indicators of the sagittal plane evaluation method are that the maximum displacement of the pelvic floor tissues and organs and the entire pelvic floor model is small, the cervical descent is small and the suspension height reduction effect is the best, the degree of organ prolapse in the pelvic floor is reduced, the stress concentration area is transferred from the middle and lower segments of the vaginal wall to the middle and upper segments, the stress of the perineal body is reduced, and the stress is transferred to the uterus (fundus uteri and cervix) and the middle and upper segments of the vagina, and the bladder stress is concentrated on the bladder apex, body, anterior bladder neck, and anterior perineal body, indicating that the suspension reconstruction surgery has achieved a good anatomical suspension height reduction effect. For uterus and sacral suspension, at the D1 suspension position, the maximum displacement of the uterus and vagina, cervix, levator ani, rectum, perineum and the whole pelvic floor model was the smallest, the cervix suspension height reduction effect was the best, the posterior vaginal wall bulge was reduced to the minimum, the vaginal physiological angle was restored, the stress concentration area was transferred from the middle and lower segments of the vaginal wall to the middle and upper segments, the stress of the perineum was the smallest, and the stress was transferred to the uterus and the middle and upper segments of the vagina. With the gradual decrease of the suspension position of S1-S5, the maximum displacement of the uterus and vagina, cervix, levator ani, rectum, perineum and the whole pelvic floor model gradually increased, the stress expanded from the uterus and the middle and upper segments of the vagina to the perineum and the middle and lower segments of the vagina, and the degree of forward and downward prolapse of the posterior vaginal wall increased again. This shows that for uterus and sacral suspension, the D1 suspension position has a good biomechanical repair effect.
[0023] 5.3) By analyzing the changes in the shape and position characteristics, mechanical support function and mechanical axial relationship of the pelvic floor organs under the action of the surgical mesh, possible complications of the pelvic floor after surgery can be predicted.
[0024] The beneficial effects of the present invention are:
[0025] (1) The method of the present invention starts from a clinical perspective, takes the clinically prolapsed female pelvic floor as the research object, and develops a two-dimensional sagittal plane prolapse biomechanical finite element model of the pelvic floor with pathological shape and position characteristics. It can more accurately simulate the suspension reconstruction surgery of the prolapsed pelvic floor, evaluate the suspension reconstruction method and surgical effect of the prolapsed pelvic floor, and provide new directions and theoretical basis support for the study of the mechanism of POP and clinical treatment, and provide an evaluation method and support basis for the physiological mechanical reconstruction surgery of the prolapsed pelvic floor. At the same time, the method of the present invention can provide a simulation platform for clinical surgical treatment. On this basis, the simulation of suspension reconstruction surgery can be carried out, and the effect of the surgery can be observed in the most intuitive way, which can make up for the shortcomings of the surgery and improve the surgical method, reduce the recurrence rate of the surgery, and provide a certain reference value for the clinical study of the mechanism of POP and the formulation and improvement of clinical surgical plans.
[0026] (2) The present invention analyzes and explores the changes in the biomechanics of the pelvic floor after surgery and its impact on patients, analyzes the changes in the overall shape and position characteristics of the pelvic floor organs, the supporting function and the pelvic floor mechanics under the action of the surgical mesh, and predicts possible complications after surgery. This enables us to prevent the occurrence of complications in a timely manner, change and optimize the surgical method to reduce the occurrence of surgical complications, improve the success rate of surgery and reduce the recurrence rate of surgery. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present application, but do not constitute an improper limitation of the present invention. In the drawings:
[0028] Figure 1 It is a flow chart of the implementation of the present invention;
[0029] Figure 2 is the MR image of the subject in the midsagittal plane;
[0030] Figure 3 It is a two-dimensional sagittal plane geometric model of pelvic floor prolapse with prolapse shape and position characteristics;
[0031] Figure 4 It is an accurate two-dimensional finite element model of female prolapsed pelvic floor with pathological shape and position characteristics under the sagittal plane, in which S is the sacrum, USL is the sacral ligament, U is the uterus, B is the bladder, RL is the round ligament, PB is the pubis, AVW is the anterior vaginal wall, APS is the paravaginal support, PUL is the pubourethral ligament, PPS is the anterior and posterior vaginal wall support, PM is the perineal membrane support, PeB is the perineal body, LA is the levator ani muscle, PVW is the posterior vaginal wall, R is the rectum, and CL is the main ligament;
[0032] Figure 5 It is an equivalent mechanical model of the uterosacral suspension simulation model using a Y-shaped surgical mesh in the sagittal plane;
[0033] Figure 6 Schematic diagram of uterosacral suspension using Y-shaped surgical mesh at D1, D2, D3, D4, and D5 positions. DETAILED DESCRIPTION
[0034] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0035] Example 1: Figure 1-6 As shown in the figure, a method for simulating and evaluating sagittal plane of pelvic floor suspension reconstruction surgery for prolapse is shown in the figure, and the steps are as follows:
[0036] Step 1: Select a female volunteer with pelvic organ prolapse and perform midsagittal imaging of the subject using 3.0T high-field magnetic resonance imaging. The field of view is 20cm×20cm, the slice thickness is 4mm, and the interval is 1mm. Take the MR image of the subject in the midsagittal plane ( Figure 2 ). The MRI data were imported into Mimics 21.0, and the morphological feature points of the pelvic floor tissues and organs were marked to obtain the accurate contours and geometric parameters of the pelvic floor organ morphology, such as the length in the sagittal plane, tissue thickness, and the angle with the horizontal plane. The data of the obtained morphological feature points were imported into the 3D design software Solidworks, and the b-sample curve was approximated three times. After multiple iterations, a 2D sagittal plane prolapse geometric model of the pelvic floor with pathological shape and position characteristics was obtained ( Figure 3 ).
[0037] Step 2: Using finite element software, establish an accurate two-dimensional finite element model of female prolapsed pelvic floor with pathological shape and position characteristics under the sagittal plane based on the two-dimensional sagittal plane prolapse geometric model of pelvic floor with pathological shape and position characteristics obtained in step 1 ( Figure 4 ). The specific implementation steps are:
[0038] 2.1) Import the two-dimensional equivalent model of the prolapsed pelvic floor obtained in step 1 into the finite element analysis software AnsysAPDL, and select the solid unit Solid185 unit and the surface scanning method to divide the model into hexahedral meshes.
[0039] 2.2) Spring elements are used to simulate the ligaments in the pelvic cavity. The main ligament is connected from the cervical ring to the lateral wall of the pelvis, the uterosacral ligament is connected from the cervical ring to the second or third segment of the sacrum and coccyx, and the remaining ligaments are connected to other tissues to simulate the pubourethral ligament (PUL), round ligament (RL), anterior and posterior vaginal wall support (PPS), paravaginal support (APS) and perineal membrane support (PM). The main ligament and uterosacral ligament are simulated using combine39 nonlinear spring elements, and the remaining ligaments and surgical mesh are simulated using combine14 spring elements.
[0040] 2.3) Use nonlinear hyperelastic material ontology model to characterize the biological soft tissue material properties of the prolapsed pelvic floor. In current research, the material properties of the biological soft tissue of the pelvic floor are generally characterized by nonlinear hyperelastic material ontology models such as Mooney-Rivlin, Ogden, Neo-Hookean, and Yeoh. Among them, the Neo-Hookean material model has the worst fitting effect and cannot capture the nonlinear behavior of biological tissue materials, while the Ogden and Yeoh material models show the best fitting effect.
[0041] 2.4) For the contact behavior between pelvic floor tissues and organs such as bladder and uterus and vagina, anterior and posterior walls of vagina, posterior wall of vagina and rectum, posterior wall of vagina and perineal body, perineal body and rectum, rectum and levator ani muscle, and the contact action inside each tissue and organ, the self-contact mechanics method is adopted, Contact174 is selected as the contact unit, Target170 is selected as the target unit, and the standard frictionless, limited slip and penalty function contact algorithm is used to define it to prevent penetration and separation between tissues and organs.
[0042] 2.5) The boundary conditions are determined by the anatomical structure of the pelvic floor, the pelvic structure and the imaging anatomical analysis structure of the subjects. The boundary conditions are mainly based on the displacement restrictions of the nodes of the finite element model. The pelvic structure is the bone support of the pelvic floor. In order to ensure its support function for the pelvic floor in this model, we use fixed constraints on the pubic bone and the sacrum. In order to make the model move only in the two-dimensional sagittal plane (XY plane), we restrict the displacement of the entire model in the coronal direction (Z direction). The origin of CLs, round ligaments, bladder support and paravaginal support is the pelvic wall, and their origins are also fixedly constrained. At the same time, we restrict the freedom of the external urethral orifice, the external vaginal orifice, the bottom of the perineal body and the levator ani muscle, and use spring units to simulate ligaments to connect them with surrounding tissues to ensure that their physiological state is basically stable and more in line with the actual situation.
[0043] 2.6) IAP selected 8.4cmH2O, 37.5cmH2O and 83.9cmH2O. Since the abdominal pressure of the pelvic floor is considered to be uniform, we load the abdominal pressure on the surface of the uterus and bladder and perpendicular to their surfaces. Because in clinical diagnosis, there is urine in the bladder, and urine has a force transmission effect, which will transfer part of the abdominal pressure at the top of the bladder to the inner posterior wall of the bladder and act on the anterior wall of the vagina. Since bladder urine was not considered in this work, but in order to be more realistic, we transferred part of the abdominal pressure at the top of the bladder to the posterior wall of the inner wall of the bladder.
[0044] 2.7) The stress-strain curves of healthy cardinal ligaments, sacral ligaments and vagina were obtained by uniaxial tensile test, and the stress-strain curves were multiplied by given factors (0.75, 0.50, 0.25) to obtain cardinal ligament, sacral ligament and vaginal tissue data sets. The obtained cardinal ligament, sacral ligament and vaginal tissue data sets were input into Ansys software, and the material parameters and stress-strain curves of 50% damage to the cardinal ligament and uterosacral ligament and 0%, 25%, 50% and 75% damage to the posterior wall of the vagina were obtained by using the curve fitting algorithm.
[0045] Step 3: This example uses hysterosacral suspension and a Y-shaped surgical mesh. The material properties of the surgical mesh come from the inspection report of the China Food and Drug Inspection Institute.
[0046] Step 4: Determine the starting and ending points of the surgical mesh suture in the female pelvic floor, and use Hooke's law and the combined force method to obtain the mechanical projection relationship of the surgical mesh on the sagittal plane of the prolapsed pelvic floor. Calculate the equivalent stiffness mechanical parameters of the surgical mesh, and use a certain number of evenly distributed spring units to simulate the equivalent mechanical effect of the surgical mesh, and obtain the equivalent mechanical model of the uterine sacral suspension pelvic floor model in the sagittal plane ( Figure 5 The surgical mesh is only shown in position D1). The specific implementation steps are:
[0047] 4.1) Choose uterosacral suspension and use Y-shaped surgical mesh.
[0048] 4.2) One end of the surgical mesh is fixed to D0 (no mesh suspension), D1 (suspended at the front edge of sacral 1), D2 (suspended at the front edge of sacral 2), D3 (suspended at the front edge of sacral 3), D4 (suspended at the front edge of sacral 4), D5 (suspended at the front edge of sacral 5), and the other end is fixed to the uterus ( Figure 6 ).
[0049] 4.3) Project the three-dimensional mechanical action of the surgical mesh in the pelvic floor onto the median sagittal plane and calculate the combined mechanical action of the surgical mesh on the median sagittal plane.
[0050] 4.4) According to Hooke's law and the principle of mechanical balance, the calculation formula for the synthetic force of the mechanical projection of the surgical mesh in the midsagittal plane is:
[0051] F = -2 × K × cos(θ / 2) × a(1)
[0052] Where: F is the tensile load on the surgical mesh (N); the negative sign indicates that the elastic force generated by the spring is opposite to its elongation direction; K is the stiffness of the surgical mesh (N / mm); θ is twice the projected angle between a single surgical mesh and the midsagittal plane (°); a is the elastic deformation or tensile displacement (mm).
[0053] 4.5) Proportional coefficient K of spring element stiffness parameter w The calculation formula is:
[0054] K w =n×b(2)
[0055] b=L1×L2(3)
[0056] Where b is the size ratio coefficient; n is the number of spring units with approximately even distribution of equivalent action; surgical mesh L1 is the equivalent width of each pelvic organ; L2 is the average width of each pelvic organ.
[0057] 4.6) From 4.4) and 4.5), the equivalent mechanical effect of the surgical mesh in the midsagittal plane can be calculated as:
[0058] F d =F / K w (4)
[0059] where F d Equivalent to surgical mesh.
[0060] 4.7) From the above formulas, the equivalent stiffness K of the surgical mesh can be obtained: d , expressed as:
[0061]
[0062] Step 5: Perform finite element simulation analysis on the equivalent mechanical model of the uterine sacral suspension pelvic floor model obtained in step 4 above in the sagittal plane. The effects of suspension reconstruction surgery and surgical mesh are evaluated by the sagittal plane evaluation method after prolapse pelvic floor surgery, and the changes in postoperative pelvic floor biomechanics and the impact on prolapse pelvic floor are analyzed and discussed. The specific implementation process is:
[0063] 5.1) Under the action of abdominal pressure, the results of simulating the surgical mesh in six equivalent positions: D0 (no mesh suspension), D1 (suspended at the front edge of sacral 1), D2 (suspended at the front edge of sacral 2), D3 (suspended at the front edge of sacral 3), D4 (suspended at the front edge of sacral 4), and D5 (suspended at the front edge of sacral 5).
[0064] 5.2) The simulation results show that in the D1 hanging position, the maximum displacement of the uterine vagina, cervix, levator ani, rectum, perineal body and the whole pelvic floor model is the smallest, the cervical suspension height reduction effect is the best, the posterior vaginal wall bulge is reduced to the minimum, the vaginal physiological angle is restored, the stress concentration area is transferred from the middle and lower part of the vaginal wall to the middle and upper part, the stress of the perineal body is the smallest, and the stress is transferred to the uterus and the middle and upper part of the vagina. With the gradual decrease of the suspension position of S1-S5, the maximum displacement of the uterine vagina, cervix, levator ani, rectum, perineal body and the whole pelvic floor model gradually increases, and the stress expands from the uterus and the middle and upper part of the vagina to the perineal body and the middle and lower part of the vagina, and the degree of forward and downward prolapse of the posterior vaginal wall increases again. This shows that for the uterine sacral suspension, there is a good biomechanical repair effect at the D1 hanging position.
[0065] 5.3) By analyzing the changes in the shape and position characteristics, mechanical support function and mechanical axial relationship of the pelvic floor organs under the action of the surgical mesh, possible complications of the pelvic floor after surgery can be predicted.
[0066] The method proposed by the present invention can observe the effect of the surgery on the prolapsed pelvic floor in the most intuitive way, provide a preview and opportunity to make up for the deficiencies of clinical surgery, provide a new direction and theoretical basis for the study of the mechanism of POP occurrence and clinical treatment, and provide an evaluation method and support basis for the physiological mechanical reconstruction surgery of pathological prolapsed pelvic floor. At the same time, it can also make the simulation more in line with the actual clinical phenomena and diagnosis and treatment results, provide a convenient and effective processing method, and greatly shorten the time spent on the simulation process.
[0067] The specific calculation method of the present invention is described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation mode. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.
Claims
1. A method for simulating and evaluating sagittal plane of pelvic floor prolapse suspension reconstruction surgery, characterized in that: The specific steps are as follows: Step 1: Use 3.0T high-field magnetic resonance imaging to perform midsagittal imaging of different age groups, different degrees of pelvic organ prolapse and different types of prolapsed pelvic floor in clinical practice. Based on MRI technology and imaging analysis data, combined with computer-aided design software, accurately reconstruct the model of each organ supported by the pelvic floor to obtain a two-dimensional sagittal prolapse geometric model of the pelvic floor with pathological shape and position characteristics; Step 2: Using finite element software, an accurate two-dimensional finite element model of a female prolapsed pelvic floor with pathological shape and position characteristics under the sagittal plane is established based on the two-dimensional sagittal plane prolapse geometric model of the pelvic floor with pathological shape and position characteristics obtained in step 1; Step 3: Select different types of surgical meshes according to different suspension reconstruction surgeries, and obtain the specific material performance parameters of the surgical meshes through mesh mechanical experiments or test reports; Step 4: According to the selected suspension reconstruction surgery and surgical mesh type, determine the starting and ending positions of the surgical mesh suture in the female pelvic floor, use Hooke's law and the combined force method to construct the mechanical projection relationship of different suspension reconstruction surgeries and surgical meshes on the sagittal plane of the prolapsed pelvic floor, calculate the equivalent stiffness mechanical parameters of the surgical mesh, and use an evenly distributed damping spring to simulate the equivalent mechanical properties of the surgical mesh, and construct the equivalent mechanical model of the prolapsed pelvic floor sagittal plane of different types of suspension reconstruction surgeries and surgical meshes; Step 5: Perform finite element simulation analysis on the sagittal equivalent mechanical model of the prolapsed pelvic floor obtained in step 4 above, evaluate the effects of suspension reconstruction surgery and surgical mesh through the sagittal plane evaluation method after prolapsed pelvic floor surgery, and analyze and explore the changes in postoperative pelvic floor biomechanics and its impact on the prolapsed pelvic floor.
2. A method for simulating and evaluating sagittal plane of pelvic floor prolapse suspension reconstruction surgery according to claim 1, characterized in that: The specific steps in step 4 are: 4.1) Select the type of suspension reconstruction surgery and determine the type of surgical mesh to be used; 4.2) Determine the starting and ending points of the surgical mesh suture in the female pelvic floor: For uterosacral suspension, the equivalent positions of the surgical mesh are: no mesh suspension D0, suspension at the front edge of sacral 1 D1, suspension at the front edge of sacral 2 D2, suspension at the front edge of sacral 3 D3, suspension at the front edge of sacral 4 D4, suspension at the front edge of sacral 5 D5; 4.3) Equivalently calculate the three-dimensional mechanical action of the surgical mesh in the pelvic floor to the median sagittal plane, and calculate the combined mechanical action of the surgical mesh in the median sagittal plane; 4.4) According to Hooke's law and the principle of mechanical equilibrium, the formula F = -2 × K × cos (θ / 2) × a is used to obtain the resultant force of the surgical mesh in the midsagittal plane, where F is the tensile load on the surgical mesh, in N; the negative sign indicates that the elastic force generated by the equivalent spring of the surgical mesh is opposite to its elongation direction; K is the stiffness of the surgical mesh, in N / mm; θ is twice the projected angle between a single surgical mesh and the midsagittal plane, in °; a is the elastic deformation or tensile displacement, in mm; 4.5) Using formula K w =n×b and b=L1×L2, and the proportional coefficient K of the equivalent damping spring stiffness parameter of the surgical mesh is obtained. w , where b is the size ratio coefficient; n is the number of spring units with approximately even distribution of equivalent action; L1 is the equivalent width of each pelvic organ; L2 is the average width of each pelvic organ; 4.6) From 4.4) and 4.5), the equivalent mechanical effect of the surgical mesh in the midsagittal plane is F d =F / K w , where F d Equivalent to surgical mesh; 4.7) From the above formulas, the equivalent stiffness K of the surgical mesh can be obtained: d , expressed as:
3. The method for simulating and evaluating sagittal plane of a prolapsed pelvic floor suspension reconstruction surgery according to claim 1, characterized in that: The specific steps in step 5 are: 5.1) Under the action of abdominal pressure, the results of simulating the equivalent position of the surgical mesh. For uterine sacral suspension, the results of simulating the equivalent position of the surgical mesh are the results of six working conditions: suspension without mesh D0, suspension at the front edge of sacral 1 D1, suspension at the front edge of sacral 2 D2, suspension at the front edge of sacral 3 D3, suspension at the front edge of sacral 4 D4, and suspension at the front edge of sacral 5 D5; 5.2) Evaluate the biomechanical repair effect of the surgical mesh in the equivalent position: Under the action of the surgical mesh, the evaluation indicators of the sagittal plane evaluation method are that the maximum displacement of the pelvic floor tissues and organs and the entire pelvic floor model is small, the cervical descent is small and the suspension height reduction effect is the best, the degree of organ prolapse in the pelvic floor is reduced, the stress concentration area is transferred from the middle and lower segments of the vaginal wall to the middle and upper segments, the stress of the perineum is reduced, and the stress is transferred to the uterus and the middle and upper segments of the vagina. The bladder stress is concentrated on the bladder apex, body, anterior bladder neck, and anterior perineum. This indicates that the suspension reconstruction surgery has a good anatomical suspension height reduction effect. For the uterine sacral suspension, when in the D1 suspension position, the uterine vagina, cervix, and anal levator The maximum displacement of the uterine sacral bone, rectum, perineal body and the whole pelvic floor model was the smallest, the cervical suspension height reduction effect was the best, the forward bulge of the posterior vaginal wall was reduced to the minimum, the physiological angle of the vagina was restored, the stress concentration area was transferred from the middle and lower segments of the vaginal wall to the middle and upper segments, the stress of the perineal body was the smallest, and the stress was transferred to the uterus and the middle and upper segments of the vagina. With the gradual decrease of the sacral 1-sacral 5 suspension position, the maximum displacement of the uterine vagina, cervix, levator ani muscle, rectum, perineal body and the whole pelvic floor model gradually increased, and the stress expanded again from the uterus and the middle and upper segments of the vagina to the perineal body and the middle and lower segments of the vagina, and the degree of forward and downward prolapse of the posterior vaginal wall increased again. This shows that for the uterine sacral suspension, it has a good biomechanical repair effect at the D1 suspension position; 5.3) By analyzing the changes in the shape and position characteristics, mechanical support function and mechanical axial relationship of the pelvic floor organs under the action of the surgical mesh, possible complications of the pelvic floor after surgery can be predicted.