A Simulation Analysis of Maternal Pelvic Floor Muscle

Simulation of Uterus Active Contraction and Fetus Delivery in ls-dyna

Vaginal childbirth is the final phase of pregnancy when one or more fetuses pass through the birth canal from the uterus, and it is a biomechanical process. The uterine active contraction, causing the pushing force on the fetus, plays a vital role in regulating the fetus delivery process. In this project, the active contraction behaviors of muscle tissue were first modeled and investigated. After that, a finite element method (FEM) model to simulate the uterine cyclic active contraction and delivery of a fetus was developed in ls-dyna. The active contraction was driven through contractile fibers modeled as one-dimensional truss elements, with the Hill material model governing their response. Fibers were assembled in the longitudinal, circumferential, and normal (transverse) directions to correspond to tissue microstructure, and they were divided into seven regions to represent the strong anisotropy of the fiber distribution and activity within the uterus. The passive portion of the uterine tissue was modeled with a Neo Hookean hyperelastic material model. Three active contraction cycles were modeled. The cyclic uterine active contraction behaviors were analyzed. Finally, the fetus delivery through the uterus was simulated. The model of the uterine active contraction presented in this paper modeled the contractile fibers in three-dimensions, considered the anisotropy of the fiber distribution, provided the uterine cyclic active contraction and propagation of the contraction waves, performed a large deformation, and caused the pushing effect on the fetus. This model will be combined with a model of pelvic structures so that a complete system simulating the second stage of the delivery process of a fetus can be established.

Quantifying the effects of five rehabilitation training methods on the ability of elderly men to control bowel movements: a finite element analysis study

Purpose

The study aims to develop a finite element model of the pelvic floor and thighs of elderly men to quantitatively assess the impact of different pelvic floor muscle trainings and the urinary and defecation control ability.

Methods

A finite element model of the pelvic floor and thighs of elderly men was constructed based on MRI and CT. Material properties of pelvic floor tissues were assigned through literature review, and the relative changes in waistline, retrovesical angle (RVA) and anorectad angulation (ARA) to quantitatively verify the effectiveness of the model. By changing the material properties of muscles, the study analyzed the muscle strengthening or impairment effects of the five types of rehabilitation training for four types of urination and defecation dysfunction. The changes in four outcome indicators, including the retrovesical angle, anorectad angulation, stress, and strain, were compared.

Results

This study indicates that ARA and RVA approached their normal ranges as material properties changed, indicating an enhancement in the urinary and defecation control ability, particularly through targeted exercises for the levator ani muscle, external anal sphincter, and pelvic floor muscles. This study also emphasizes the effectiveness of personalized rehabilitation programs including biofeedback, exercise training, electrical stimulation, magnetic stimulation, and vibration training and advocates for providing optimized rehabilitation training methods for elderly patients.

Discussion

Based on the results of computational biomechanics, this study provides foundational scientific insights and practical recommendations for rehabilitation training of the elderly's urinary and defecation control ability, thereby improving their quality of life. In addition, this study also provides new perspectives and potential applications of finite element analysis in elderly men, particularly in evaluating and designing targeted rehabilitation training.

Finite element analysis of female pelvic organ prolapse mechanism: current landscape and future opportunities

The prevalence of pelvic organ prolapse (POP) has been steadily increasing over the years, rendering it a pressing global health concern that significantly impacts women's physical and mental wellbeing as well as their overall quality of life. With the advancement of three-dimensional reconstruction and computer simulation techniques for pelvic floor structures, research on POP has progressively shifted toward a biomechanical focus. Finite element (FE) analysis is an established tool to analyze the biomechanics of complex systems. With the advancement of computer technology, an increasing number of researchers are now employing FE analysis to investigate the pathogenesis of POP in women. There is a considerable number of research on the female pelvic FE analysis and to date there has been less review of this technique. In this review article, we summarized the current research status of FE analysis in various types of POP diseases and provided a detailed explanation of the issues and future development in pelvic floor disorders. Currently, the application of FE analysis in POP is still in its exploratory stage and has inherent limitations. Through continuous development and optimization of various technologies, this technique can be employed with greater accuracy to depict the true functional state of the pelvic floor, thereby enhancing the supplementation of the POP mechanism from the perspective of computer biomechanics.

Influence of Different Obstetric Factors on Early Postpartum Pelvic Floor Function in Primiparas After Vaginal Delivery

Purpose

This study sought to explore the obstetric factors affecting early postpartum pelvic floor function of primiparas after vaginal delivery.

Patients and Methods

We included 3362 primiparas who underwent postpartum re-examination in International Peace Maternity and Child Health Hospital at 42-60 days after delivery. The Glazer Protocol was used to evaluate their pelvic floor function, and univariate and multivariate logistic regression analyses were performed to identify obstetric factors that might affect it.

Results

Forceps-assisted delivery significantly increased the risk of the decline in fast- and slow-twitch muscle strength in the early postpartum period when compared with natural vaginal delivery (P < 0.05). Women with a pre-pregnancy body mass index (BMI) of ≥18.5 kg/m² had a decreased risk of decline in fast-twitch muscle strength than those with a pre-pregnancy BMI of <18.5 kg/m² (P < 0.05). Women who had a pre-pregnancy BMI of 24.0 to <28.0 kg/m² bore a decreased risk of decline in slow-twitch muscle strength than those with a pre-pregnancy BMI of <18.5 kg/m² (P < 0.05). The risk of decline in fast-twitch muscle strength and slow-twitch muscle in women with anemia during pregnancy was significantly increased (P < 0.05); women with second-stage labors of >2 h had an increased risk of fast-twitch and slow-twitch muscle strength decline than those with <2 h (P < 0.05).

Conclusion

Both pre-pregnancy underweight and obesity may cause impairment of early postpartum pelvic floor function. Forceps delivery, anemia during pregnancy, and the length of second stage of labor are independent factors leading to pelvic floor function impairment.

Association of cesarean delivery timing with pelvic floor muscle function and urine incontinence: A propensity score-matched study

Pelvic floor dysfunction is a common gynecological disease that adversely affects women's quality of life and mental health. Delivery is considered a significant independent risk factor for pelvic floor dysfunction. Surface electromyography (sEMG) values for the pelvic floor muscles (PFM) have been shown to differ according to different delivery modes. This study aimed to compare sEMG results between intrapartum and antepartum cesarean delivery (CD), 42-60 days after delivery. Data of women who underwent CD at the International Peace Maternity and Child Health Hospital were collected from September 2021 to December 2021. Myotrac Infiniti System was used to measure the electromyographic activity of PFM after 42-60 days of parturition. Propensity score matching (1:1) was applied to achieve a balance in baseline data between the two groups (intrapartum and antepartum CD). A total of 200 paired cases were selected for statistical analysis. In the propensity score-matched analysis, there were no statistically significant differences in PFM sEMG between women with antepartum or intrapartum CD (p > 0.05 for all). We observed similar results with postpartum urinary incontinence (24 [12.0] vs. 21 [10.5]; adjusted odds ratio (aOR), 1.12 [95% confidence interval (CI) 0.60-2.12]; p = 0.717) and stress urinary incontinence (12 [6.0] vs. 14 [7.0]; aOR, 0.80 [95% CI 0.35-1.80]; p = 0.596) as outcomes. After excluding participants with intrapartum CD when the cervix was dilated <6 cm, all sEMG of PFM had a comparable level of risk in both the antepartum and intrapartum CD groups. There were no significant differences in sEMG of the PFM and the incidence of urinary incontinence between patients undergoing intrapartum or antepartum CD. Excluding women who underwent intrapartum CD when the cervix was dilated to <6 cm produced little change in results. Thus, different opportunities for CD may not impact the sEMG of the PFM and the incidence of urinary incontinence.

Prevalence, Knowledge and Awareness of Pelvic Floor Disorder among Pregnant Women in a Tertiary Centre, Malaysia

Pelvic floor disorders are common and of concern, as the majority of maternity healthcare providers seldom discuss this issue with patients compared to other antenatal issues. The aim of this study is to determine the prevalence and to assess the knowledge and awareness of pelvic floor disorder (PFD) among pregnant women in a tertiary centre in Malaysia. We also aim to assess the association between women’s risk factors regarding their knowledge and awareness of pelvic floor disorder so that primary prevention strategies can be planned, initiated and implemented in the future. This is a cross-sectional study with a total of four hundred twenty-four pregnant women that were recruited over a 6-month duration from May to November 2017 in a tertiary centre in Malaysia. The Pelvic Floor Distress Inventory (PFDI-20) was used to evaluate pelvic floor distress symptoms during pregnancy, namely urinary incontinence, pelvic organ prolapse and faecal incontinence. A validated Prolapse and Incontinence Knowledge Questionnaire (PIKQ), which consists of 24 items, was used to assess respondents’ knowledge about urinary incontinence (UI) and pelvic organ prolapse (POP). A total of 450 participants were approached, but 424 participants agreed to participate, showing a response rate of 94.3%. The median age was 31.5 years old, and 33.3% were primiparity. Overall, 46.1% of pregnant women had at least one symptom of pelvic floor disorder during pregnancy. Of these, 62.3% experienced urinary incontinence, 41.1% experienced symptoms of pelvic organ prolapse, and 37.8% experienced symptoms of faecal incontinence. The overall median score of PIKQ was 12.0 (8.0, 17.0). The median score for PIKQ—UI was 7.0 (5.0, 9.0) and the median score for PIKQ—POP was 6.0 (4.0, 8.0). There were 341 (80.4%) pregnant women that had a low level of knowledge in UI, and 191 (45.0%) had a low level of knowledge in POP. Having a tertiary level of education and receiving antenatal specialist care were both associated with better proficiency in both the PIKQ—UI (p < 0.001) and PIKQ—POP (p < 0.001) subscales. Pelvic floor disorder during pregnancy was common. A knowledge of pelvic floor disorder was lacking among pregnant women in this study. Having a tertiary education and receiving antenatal specialist care were both associated with better knowledge proficiency. This study hopefully serves as a basic platform for future educational programs to bridge the knowledge gaps in PFD among pregnant women.

Computation of Fetal Kicking in Various Fetal Health Examinations: A Systematic Review

Fetal movement has always been considered an essential indicator to evaluate the health of the unborn fetus. Many factors affect fetal movement. The frequency of fetal kicking is an important measurement of whether fetal development is progressing and healthy. Various instruments and methods of detecting fetal movement have been used and each method has its advantages and disadvantages. Although limited by the fetal environment in utero, the finite element method and musculoskeletal model can be used to calculate fetal lower limb movement. This review aims to summarize the current detection techniques for fetal movement, especially in the lower limbs. These will be outlined by describing the different measurements of fetal movement, and the related biomechanical analyses of fetal lower limb skeletogenesis and the associated muscular development to better evaluate and calculate the movements of the fetus in the womb.

Effect of Displacement Degree of Distal Chevron Osteotomy on Metatarsal Stress: A Finite Element Method

BACKGROUND

The stress of foot bone can effectively evaluate the functional damage caused by foot deformity and the results of operation. In this study, the finite element method was used to investigate the degree of displacement of distal chevron osteotomy on metatarsal stress and metatarsophalangeal joint load; Methods: Four finite element models of displacement were established by using the CT images of a patient with moderate hallux valgus (hallux valgus angle and intermetatarsal angle were 26.74° and 14.09°, respectively), and the validity of the model was verified. Each finite element model consisted of bones and various cartilage structures, ligaments, and plantar fascia, as well as encapsulated soft tissue. Except for soft tissue, the material properties of other parts were isotropic linear elastic material, and the encapsulated soft tissue was set as nonlinear hyperelastic material. The mesh was tetrahedral mesh. Link elements were used in ligament and plantar fascia. A ground reaction force with a half-body weight was applied at the bottom of the floor to simulate the ground reaction when standing. The upper surfaces of the encapsulated soft tissue, distal tibia, and distal fibula were fixed. The stress distribution of metatarsals and the stress of cartilage of the first metatarsophalangeal joint were compared and analyzed; Results: Compared with the hallux valgus without osteotomy, the stress of the first metatarsals and second metatarsals of 2-4 mm decreased, and the stress of the interarticular cartilage of the first metatarsophalangeal joint with 4 mm was reduced. In the case of 6 mm, the stress value between the first metatarsal and the first metatarsophalangeal joint increased, and 4 mm was the most suitable distance; Conclusions: Compared with the hallux valgus without osteotomy, the stress of the first metatarsals and second metatarsals of 2-4 mm decreased, and the stress of the interarticular cartilage of the first metatarsophalangeal joint with 4 mm was reduced. In the case of 6 mm, the stress value between the first metatarsal and the first metatarsophalangeal joint increased, and 4 mm was the most suitable distance. For the degree of displacement of the distal chevron osteotomy, the postoperative stability and the stress distribution of metatarsal bone should be considered. Factors such as hallux valgus angle, intermetatarsal angle, patient's age, body weight, and metatarsal width should be considered comprehensively. The factors affecting osteotomy need to be further explored. The degree of displacement of osteotomy can be evaluated by FE method before the operation, and the most suitable distance can be obtained.