Age-associated changes in the mechanical properties of human cadaveric pelvic floor muscles

Dynamic shear wave elastography for the flexor digitorum superficialis: The correlation with physical performance in hospitalized older adults

Shear wave elastography (SWE) can quantify muscle stiffness to reflect the muscle quality, and we explored the application of SWE in assessing physical performance. In this work, a total of 98 older adults, including 55 men and 43 women, were recruited in this cross-sectional study. Short physical performance battery (SPPB) and time-up-and-go (TUG) test were used to evaluate physical performance, and a dynamic SWE imaging for the flexor digitorum superficialis in the process of using grip strength meter was documented. The peak strength and peak shear wave velocities (SWV) were recorded, and the ratio of peak SWV to peak strength was defined as the standardized muscle contractive stiffness. For men, the peak SWV was negatively correlated to SPPB scores (r = -0.351 to -0.448, all P < 0.01) and positively correlated to TUG time (r = 0.299-0.369, all P < 0.05), and the standardized muscle contractive stiffness was significantly negatively correlated to SPPB scores (r = -0.501 to -0.532, all P < 0.01) and positively correlated to TUG time (r = 0.424-0.462, all P < 0.01). For women, the peak SWV was not correlated to physical performance, and the standardized muscle contractive stiffness was correlated to the TUG time (r = 0.312 for Cmax and 0.310 for Cmean, both P < 0.05). Those participants with decreased physical performance had significant higher standardized muscle contractive stiffness in both men and women (all P < 0.05). We proved that SWE can be applied in evaluating muscle function and the flexor digitorum superficialis contractive stiffness standardized by grip strength can be a potential indicator.

Older maternal age at first delivery as a risk factor for pelvic organ prolapse: what we know

Older chronological age and vaginal childbirth are widely accepted risk factors of pelvic organ prolapse. However, considerably less attention has been given to the impact of maternal age at first delivery. Ample research has demonstrated the deleterious effects of age on the musculoskeletal system, including the loss of muscle mass and strength as well as diminished recovery after stress. Little research has evaluated the role of these local muscle changes in the development of pelvic organ prolapse when childbearing is delayed. As the average age of first-time mothers continues to increase, evaluating age at first delivery as a predictor of pelvic organ prolapse development is highly relevant. In this review, we present the evidence demonstrating that increased maternal age increases pelvic organ prolapse risk. Additionally, evidence regarding the effects of age at first delivery on mechanisms of pelvic organ prolapse including pelvic muscle dysfunction, levator ani defects, and genital hiatus enlargement is presented.

Are pelvic floor muscle function, quadriceps femoris muscle, gluteus medius muscle, hand grip strength and functional performance affected by incontinence types in elderly people with urinary incontinence?

AIM

The aim of this study is to examine the relationship between incontinence type and pelvic floor muscle function, gluteus medius muscle, quadriceps femoris muscle, hand grip strength, functional performance and balance in elderly people with incontinence.

MATERIALS AND METHODS

This cross-sectional study was conducted in a nursing home with 78 elderly people with stress (SUI, n: 20), urgency (UUI, n: 27) and mixed (MUI, n: 31) urinary incontinence. "Urogenital Distress Inventory-6, Incontinence Impact Questionnaire Form-7, Overactive Bladder-8" were used to evaluate incontinence symptoms and severity. Superficial electromyography was used to evaluate the function of the PFM. A hand dynamometer was used to evaluate hand grip strength, and a digital manual muscle tester was used to evaluate quadriceps femoris (QF) and gluteus medius muscle strength. Short Physical Performance Battery and Time Up and Go Test were performed for functional performance.

RESULTS

There was no significant difference between PFM contraction and relaxation functions, gluteus medius, QF muscle strength, functional performance (p > 0.05) but hand grip strength was highest in the group with UUI (ptotal: 0.022). The group with the highest rate of low hand grip strength is MUI (38.7%). A weak positive correlation was found between QF muscle strength and PFM Work Average value in the MUI group (r: 0.370, p: 0.048). In the MUI group, a moderate positive correlation was found between hand grip strength and gluteus medius muscle strength (r: 0.499, p: 0.005).

CONCLUSION

Our findings show that hand grip strength is related to the type of incontinence in the elderly people. The average hand grip strength was highest in the elderly people with UUI. Additionally, there was a positive relationship between gluteus medius and hang grip strength in MUI. It may provide guidance for evaluation and risk factors in elderly people with incontinence.

Hiatus and pelvic floor failure patterns in pelvic organ prolapse: a 3D MRI study of structural interactions using a level III conceptual model

BACKGROUND

A large urogenital hiatus in level III results in a higher risk of developing pelvic organ prolapse after birth and failure after prolapse surgery. Deepening of the pelvic floor and downward rotation of the levator plate have also been linked to prolapse. Currently we lack data that evaluates how these measures relate to one another and to prolapse occurrence and size.

OBJECTIVE

This study uses measurements from a published conceptual model to compare women with and without prolapse to determine the magnitude of difference between cases and controls and to quantify the interrelationships among different aspects of pelvic floor shape and structure.

STUDY DESIGN

Ninety-one women with anterior predominant prolapse and uterus in situ who had 3D MRI and 30 similar women with normal support were studied. Resting scans were used to avoid the influence of the prolapse dilating the hiatus. Measurements assessed 3 domains: hiatus size (urogenital and levator hiatus); length of the surrounding pelvic floor muscles (pubovisceral, puborectal, iliococcygeal muscles); the shelf-like posterior pelvic floor (levator plate shape, levator bowl volume), and bony pelvic dimensions. Effect sizes were calculated and principal component shape analysis performed to evaluate levator plate shape. z scores were calculated and a value greater than 1.68 (95th percentile) was considered the "failure" criterion. Frequency and severity of structural support site failure were analyzed by prolapse size.

RESULTS

Resting urogenital and levator hiatal areas were 68% and 59% larger in the prolapse group compared to controls. These area enlargements were 2 to 4 times larger than the anterior-posterior dimension enlargements (urogenital hiatus 36%; levator hiatus 13%). The greatest muscle length differences between groups occurred in the pubovisceral (34%) and puborectal (25%) muscles compared to the iliococcygeal muscle (8%)-roughly half the area differences. Levator bowl volume was 63% deeper with prolapse. Urogenital hiatus and levator hiatus areas were strongly correlated with pubovisceral and puborectal muscle length (0.7-0.8), while iliococcygeal muscle length had lower correlations (0.4-0.5). Levator bowl volume correlated strongly with hiatal enlargement (0.7-0.8) and muscle length (pubovisceral and puborectal muscles), moderately so with levator plate and iliococcygeal muscle, and weakly with bony dimension. Failure frequency increased with prolapse size for urogenital hiatus anterior-posterior (P=.001) and area (P=.019). By contrast, levator hiatus area was similar for all prolapse sizes (P=.288), while levator hiatus anterior-posterior failure was more common in larger prolapses (P=.018) but with smaller percentages of failure than levator hiatus area (P<.01). Both levator bowl volume (P=.015) and levator plate (P=.045) trended toward increasing failure with larger prolapse sizes. Among women with enlarged urogenital hiatus at straining, 43% and 28% had normal urogenital hiatus anterior-posterior and area at rest, respectively.

CONCLUSION

Changes in the shape and dimensions of the pelvic floor are complex and are not captured by a single measure (such as the urogenital hiatus anterior-posterior dimension, which does not capture its lateral expansion). The failure patterns were different between small and large prolapses. Understanding why could lead to improved prevention and treatments for level III failures.

Pelvic Floor Muscle Evaluation in Older Women with Urinary Incontinence: A Feasibility Study

INTRODUCTION AND HYPOTHESIS

The objective of this feasibility study was to characterize the pelvic floor muscles (PFMs) in older women with urinary incontinence (UI) via clinical and magnetic resonance imaging (MRI) evaluation.

METHODS

This cross-sectional study included women aged ≥ 70 years with symptomatic UI confirmed by a 3-day bladder diary. Clinical evaluation of the PFMs included the Modified Oxford Scale strength assessment (grade 0-5). PFM defects were also characterized as none/normal, minor, and major based on MRI evaluation. Descriptive statistics were utilized. Spearman's correlation with 95% confidence intervals was calculated between PFMs strength, MRI defects, and age.

RESULTS

Participants (n = 20) were 76.6 ± 4.7 years. Clinical evaluation demonstrated poor PFM strength in 95% (n = 19) of participants with the following grades: 15% (n = 3) grade 0, 45% (n = 9) grade 1, and 35% (n = 7) grade 2. MRI evaluation demonstrated PFMs= defects in 100% of participants with 45% (n = 9) minor and 55% (n = 11) major defects. The correlation coefficients between PFM strength and MRI defects, MRI defects and age, and PFM strength and age were -0.29 (95% CI -0.64, 0.18; p = 0.22), -0.01 (95% CI = -0.44, 0.44; p = 0.99), and 0.04 (95% CI = -0.41, 0.47; p = 0.88) respectively.

CONCLUSION

Clinical and MRI evaluation of PFMs in older women with UI is feasible. Clinical evaluation of PFMs demonstrated poor strength in 95% of women, and MRI revealed PFM defects in all participants.

Pelvic floor dysfunction in postpartum women: A cross-sectional study

BACKGROUND

Pelvic floor dysfunction (PFD) is a disease of weakened pelvic floor support tissues, leading to changes in the pelvic organ position and function of pelvic organs, with long-term effects on women. This study aimed to assess pelvic floor function using electrophysiology and clinical symptoms, exploring the risk factors for PFD one month postpartum.

METHODS

This cross-sectional study included 845 women from postpartum outpatient clinic of Nantong Affiliated Hospital from August 2019 to October 2021. Pelvic floor muscle strength was evaluated via pelvic floor surface electromyography. Clinical symptoms (urinary incontinence (UI) and pelvic organ prolapse) were diagnosed by gynecologists. Sociodemographic, pregnancy, and obstetrical data were obtained from self-reported questionnaires and electronic records.

RESULTS

The study identified maternal age, parity, immigrant status, and economic income as factors were related to PFD. Gestational constipation increased the risk of abnormal resting muscle strength (OR:1.553, 95%CI: 1.022-2.359). Cesarean delivery was associated with higher rates of abnormal resting muscle strength than vaginal delivery (post-resting stage: OR, 2.712; 95% CI, 1.189-6.185), but a decreased incidence of UI (OR: 0.302; 95% CI, 0.117-0.782). Increased gestational weight gain was correlated with a greater risk of developing UI (OR:1.030, 95%CI: 1.002-1.058). Women with vaginal inflammation faced a higher risk of abnormal fast-twitch muscle (OR: 2.311, 95%CI: 1.125-4.748).

CONCLUSIONS

In addition to uncontrollable factors like mode of delivery, age, and parity, interventions targeting weight gain and constipation during pregnancy and vaginal flora could mitigate the risks of PFD. Educational programs for pregnant women should emphasize a proper diet and lifestyle. For women with vaginal inflammation, clinical treatment should be carried out as soon as possible to avoid further aggravating the damage to the pelvic floor muscles.

Muscle mechanical properties of pelvic floor and paravertebral muscles in women with and without urge urinary incontinence: a case-control study

BACKGROUND

Muscle mechanical properties (MMPs) are relevant in the pathophysiology of lumbopelvic disorders. However, they have not been described in the pelvic floor muscles (PFM) and lumbar paravertebral muscles (LPM) of women with urge urinary incontinence (UUI).

OBJECTIVE

To identify differences between MMPs of PFM and LPM in patients with UUI and healthy controls. Secondarily also aimed to observe the relationship between sociodemographic and clinical variables with the PFM and LPM MMPs.

METHODS

The participants of this case-control study comprised 34 women with UUI (UUI group) and 34 continent women (control group). Sociodemographic variables were obtained together with data on the clinical status of the pelvic floor. The MMPs, i.e., frequency (tone), stiffness, decrement (inverse of elasticity), and viscoelastic properties (VP), such as relaxation time and creep, of PFM and LPM were assessed with a hand-held tonometer. Between-group differences and intra-group correlations were identified.

RESULTS

The UUI group presented higher frequency and stiffness, as well as lower relaxation time in PFM, whereas the LPM had lower tone and stiffness, and higher VP, compared to the control group (p < 0.05). The UUI group showed a pattern of moderate correlations (|0.403|

CONCLUSION

The presence of UUI may influence MMPs at PFM and LPM levels, increasing the tone and stiffness of PFM, whereas these properties are reduced in LPM. These findings emphasize the clinical interest of the lumbopelvic determination of MMPs, obtained through externally applied hand-held instruments, in the pathophysiology of UUI.

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Key Words

• Pelvic floor disorders
• Regional interdependence
• Tonometry

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MESH Headings

• Case-Control Studies
• Lumbar Vertebrae
• Back Muscles/physiopathology
• Urinary Incontinence, Urge/physiopathology
• Pelvic Floor/physiopathology
• Humans
• Female
• Adult
• Middle Aged
• Manometry
• Muscle Tonus/physiology
• Biomechanical Phenomena
• Elasticity/physiology

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Affiliation(s)

María Teresa Garzón-Alfaro Department of Nursing, Pharmacology and Physical Therapy, Faculty of Medicine and Nursing, University of Córdoba, Córdoba, Spain
Inés Cruz-Medel Department of Nursing, Pharmacology and Physical Therapy, Faculty of Medicine and Nursing, University of Córdoba, Córdoba, Spain
Sandra Alcaraz-Clariana Department of Nursing, Pharmacology and Physical Therapy, Faculty of Medicine and Nursing, University of Córdoba, Córdoba, Spain
Lourdes García-Luque Department of Nursing, Pharmacology and Physical Therapy, Faculty of Medicine and Nursing, University of Córdoba, Córdoba, Spain
Cristina Carmona-Pérez Department of Nursing, Pharmacology and Physical Therapy, Faculty of Medicine and Nursing, University of Córdoba, Córdoba, Spain
Juan Luis Garrido-Castro Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Córdoba, Spain; Department of Computer Science and Numerical Analysis, Rabanales Campus, University of Córdoba, Córdoba, Spain
Francisco Alburquerque-Sendín Department of Nursing, Pharmacology and Physical Therapy, Faculty of Medicine and Nursing, University of Córdoba, Córdoba, Spain; Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Córdoba, Spain.
Daiana Priscila Rodrigues-de-Souza Department of Nursing, Pharmacology and Physical Therapy, Faculty of Medicine and Nursing, University of Córdoba, Córdoba, Spain; Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Córdoba, Spain

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Screening for Incidence and Effect of Pelvic Floor Dysfunction in College-Aged Athletes

Background

Pelvic floor dysfunction (PFD) occurs when muscles of the pelvic floor become weakened, impaired, or experience tension leading to a variety of complications. Due to the reactive nature and high demands of many sports, athletes are at increased susceptibility and of particular interest concerning PFD.

Hypothesis/Purpose

The purpose of this study was to explore the prevalence of PFD among college-aged athletes, assess how PFD impacted athletic performance, and identify contributing factors for increased likelihood of PFD in athletes.

Study Design

Cross-Sectional Study.

Methods

All fully active LVC NCAA Division 3 athletes were recruited for screening for PFD using the Cozean Pelvic Dysfunction Screening Protocol and were surveyed on their self-knowledge of PFD. Athletes who scored ≥ 3 on this tool completed an additional survey, created by the investigators, to identify the impact PFD had on their athletic performance and personal life and were then randomly assigned to one of three investigators to undergo a noninvasive coccygeal assessment to determine underactive, overactive, or normal pelvic floor muscle (PFM) activity.

Results

Fifty-three Division III male and female athletes between the ages of 18-25 years old participated in the study. Statistically significant differences were found between Cozean scores and demographic factors of age (p \<0.001), gender (p \<0.05), self-knowledge of PFD (p \<0.001), and sport (p \<0.001) among all participants that contributed to the increased likelihood of PFD. Thirteen athletes scored ≥ 3 on the Cozean with the 92.3% experiencing under/over active PFM activity and the majority indicating that PFD significantly impacted their athletic performance and quality of life.

Conclusion

The results indicate that older female NCAA Division III college athletes who participate in swimming and who possess self-knowledge of PFD are more likely to experience PFD. Additionally, these athletes are likely to encounter a significant impact on their athletic performance and quality of life. These results provide preliminary evidence on the need of PFD awareness and assessment among college athletes.

Level of Evidence

Level 3b.

A unified pelvic floor conceptual model for studying morphological changes with prolapse, age, and parity

Several 2-dimensional and 3-dimensional measurements have been used to assess changes in pelvic floor structures and shape. These include assessment of urogenital and levator hiatus dimensions, levator injury grade, levator bowl volume, and levator plate shape. We argue that each assessment reflects underlying changes in an individual aspect of the overall changes in muscle and fascial structures. Vaginal delivery, aging, and interindividual variations in anatomy combine to affect pelvic floor structures and their connections in different ways. To date, there is no unifying conceptual model that permits the evaluation of how these many measures relate to one another or that reflects overall pelvic floor structure and function. Therefore, this study aimed to describe a unified pelvic floor conceptual model to better understand how the aforementioned changes to the pelvic floor structures and their biomechanical interactions affect pelvic organ support with vaginal birth, prolapse, and age. In this model, the pelvic floor is composed of 5 key anatomic structures: the (1) pubovisceral, (2) puborectal, and (3) iliococcygeal muscles with their superficial and inferior fascia; (4) the perineal membrane or body; and (5) the anal sphincter complex. Schematically, these structures are considered to originate from pelvic sidewall structures and meet medially at important connection points that include the anal sphincter complex, perineal body, and anococcygeal raphe. The pubovisceral muscle contributes primarily to urogenital hiatus closure, whereas the puborectal muscle is mainly related to levator hiatus closure, although each muscle contributes to the other. Dorsally and laterally, the iliococcygeal muscle forms a shelflike structure in women with normal support that spans the remaining area between these medial muscles and attachments to the pelvic sidewall. Other features include the levator plate, bowl volume, and anorectal angle. The pelvic floor conceptual model integrates existing observations and points out evident knowledge gaps in how parturition, injury, disease, and aging can contribute to changes associated with pelvic floor function caused by the detachment of one or more important connection points or pubovisceral muscle failure.

Analysis of questions by patients with pelvic organ prolapse about vaginal pessaries resulting in a checklist for their physicians

OBJECTIVE

International guidelines recommend vaginal pessaries as a first-choice treatment of symptomatic pelvic organ prolapse (POP). Gynecologists rarely receive systematic training or just do not take the time to communicate with their patients. We hypothesized that we could identify key deficits and limitations of counseling before or during pessary therapy from questions directed to manufacturers with the aim to improve and promote health literacy of women with POP.

METHODS

We approached five manufacturers to provide anonymized inquiries related to pessary use. After exclusion of duplicates and questions about obstetric pessaries, 174 data sets from 145 patients remained.

RESULTS

In 19/145 patients (13.1%), a 2nd degree, and in 94/145 (64.8%), a 3rd-4th degree of POP was identified. Four patients had additional urinary incontinence. In 32/145 (22.1%), the severity of POP could not be identified. The age of patients ranged from 27 to 98 (mean = 63.7) years. Most inquiries were related to the selected pessary models or sizes (40/174; 22.9%), self-management (20/174; 11.5%), and technical aspects such as shelf life or appropriate cleaning (26/174; 14.9%). Pain or voiding dysfunction was present in 17/174 remarks (9.7%). Lifestyle questions related to the use of pessaries during sport, menstruation, or mechanical anticonception. The cube pessary was in the focus of interest followed by the sieve bowl, urethra, ring, and Gellhorn device. The list of questions was summarized as a checklist stratified according to priorities.

CONCLUSION

The checklist should help improve counseling and self-management of patients to optimize the benefit/risk ratio of conservative treatment of pelvic floor diseases.

Skeletal muscle aging and sarcopenia: Perspectives from mechanical studies of single permeabilized muscle fibers

The decline in muscle mass and strength with age is well documented and associated with weakness, decreased flexibility, vulnerability to diseases and/or injuries, and impaired functional restoration. The term sarcopenia has been used to refer to the loss of muscle mass, strength and impaired physical performance with advanced adult age and recently has become a major clinical entity in a super-aged society. To understand the pathophysiology and clinical manifestations of sarcopenia, it is essential to explore the age-related changes in the intrinsic properties of muscle fibers. Mechanical experiments with single muscle fibers have been conducted during the last 80 years and applied to human muscle research in the last 45 years as an in-vitro muscle function test. Fundamental active and passive mechanical properties of skeletal muscle can be evaluated using the isolated permeabilized (chemically skinned) single muscle fiber preparation. Changes in the intrinsic properties of older human single muscle fibers can be useful biomarkers of aging and sarcopenia. In this review, we summarize the historical development of single muscle fiber mechanical studies, the definition and diagnosis of muscle aging and sarcopenia, and age-related change of active and passive mechanical properties in single muscle fibers and discuss how these changes can be used to assess muscle aging and sarcopenia.

Asymmetries of the Muscle Mechanical Properties of the Pelvic Floor in Nulliparous and Multiparous Women, and Men: A Cross-Sectional Study

This study aimed to identify if the muscle mechanical properties (MMPs) of both sides of pelvic floor muscles (PFMs) are symmetrical in different populations of both sexes. Between-sides comparisons of MMPs of PFMs, assessed with manual myotonometry, were performed in three groups, with 31 subjects each, composed of healthy nulliparous women (without any type of delivery or pregnancy), multiparous women (with at least two vaginal deliveries), and healthy adult men. Intra-group correlations between MMPs and age, body mass index (BMI), or clinical state of pelvic floor were also obtained. The nulliparous women and the men showed no between-sides differences in any MMP of PFMs. However, the multiparous women showed that the right side displayed less frequency (−0.65 Hz, 95% CI = −1.01, −0.20) and decrement (0.5, 95% CI = 0.11, 0.01), and more relaxation (1.00 ms, 95% CI = 0.47, 1.54) and creep (0.07 De, 95% CI = 0.03, 0.11), than the left side. Further, MMPs were related to age, sex, and BMI, also depending on the population, with the multiparous women being the only group with some between-sides asymmetries, which in this case were positive and of fair intensity for the left side of the PFMs, between BMI, and frequency and stiffness (rho Spearman coefficient: 0.365 and 0.366, respectively). The symmetry of MMPs of the PFMs could depend on the subject’s condition. Multiparous women show a higher tendency to asymmetries than nulliparous women and men, which should be considered in research and clinical settings.

Euendolithic Cyanobacteria and Proteobacteria Together Contribute to Trigger Bioerosion in Aquatic Environments

Shellfish, mussels, snails, and other aquatic animals, which assimilate limestone (calcium carbonate, CaCO3) to build shells and skeletons, are effective carbon sinks that help mitigate the greenhouse effect. However, bioerosion, the dissolution of calcium carbonate and the release of carbon dioxide, hinders carbon sequestration process. The bioerosion of aquatic environments remains to be elucidated. In this study, the bioerosion of Bellamya spp. shells from the aquatic environment was taken as the research object. In situ microbial community structure analysis of the bioerosion shell from different geographical locations, laboratory-level infected culture, and validated experiments were conducted by coupling traditional observation and 16S rRNA sequencing analysis method. Results showed that bioeroders can implant into the CaCO3 layer of the snail shell, resulting in the formation of many small holes in the shell, which reduced the shell’s density and made the shell fragile. Results also showed that bioeroders were distributed in two major phyla, namely, Cyanobacteria and Proteobacteria. Cluster analysis showed that Cyanobacteria sp. and two unidentified genera (Burkholderiaceae and Raistonia) were the key bioeroders. Moreover, results suggested that the interaction of Cyanobacteria and other bacteria promoted the biological function of “shell bioerosion.” This study identified the causes of “shell bioerosion” in aquatic environments and provided some theoretical basis for preventing and controlling it in the aquatic industry. Results also provided new insights of cyanobacterial bioerosion of shells and microalgae carbon sequestration.

Biaxial Murine Vaginal Remodeling With Reproductive Aging

Higher reproductive age is associated with an increased risk of gestational diabetes, pre-eclampsia, and severe vaginal tearing during delivery. Further, menopause is associated with vaginal stiffening. However, the mechanical properties of the vagina during reproductive aging before the onset of menopause are unknown. Therefore, the first objective of this study was to quantify the biaxial mechanical properties of the nulliparous murine vagina with reproductive aging. Menopause is further associated with a decrease in elastic fiber content, which may contribute to vaginal stiffening. Hence, our second objective was to determine the effect of elastic fiber disruption on the biaxial vaginal mechanical properties. To accomplish this, vaginal samples from CD-1 mice aged 2-14 months underwent extension-inflation testing protocols (n = 64 total; n = 16/age group). Then, half of the samples were randomly allocated to undergo elastic fiber fragmentation via elastase digestion (n = 32 total; 8/age group) to evaluate the role of elastic fibers. The material stiffness increased with reproductive age in both the circumferential and axial directions within the control and elastase-treated vaginas. The vagina demonstrated anisotropic mechanical behavior, and anisotropy increased with age. In summary, vaginal remodeling with reproductive age included increased direction-dependent material stiffness, which further increased following elastic fiber disruption. Further work is needed to quantify vaginal remodeling during pregnancy and postpartum with reproductive aging to better understand how age-related vaginal remodeling may contribute to an increased risk of vaginal tearing.

International Urogynecological Consultation (IUC): pathophysiology of pelvic organ prolapse (POP)

INTRODUCTION AND HYPOTHESIS

This manuscript is the International Urogynecology Consultation (IUC) on pelvic organ prolapse (POP) chapter one, committee three, on the Pathophysiology of Pelvic Organ Prolapse assessing genetics, pregnancy, labor and delivery, age and menopause and animal models.

MATERIALS AND METHODS

An international group of urogynecologists and basic scientists performed comprehensive literature searches using pre-specified terms in selected biomedical databases to summarize the current knowledge on the pathophysiology of the development of POP, exploring specifically factors including (1) genetics, (2) pregnancy, labor and delivery, (3) age and menopause and (4) non-genetic animal models. This manuscript represents the summary of three systematic reviews with meta-analyses and one narrative review, to which a basic scientific comment on the current understanding of pathophysiologic mechanisms was added.

RESULTS

The original searches revealed over 15,000 manuscripts and abstracts which were screened, resulting in 202 manuscripts that were ultimately used. In the area of genetics the DNA polymorphisms rs2228480 at the ESR1 gene, rs12589592 at the FBLN5 gene, rs1036819 at the PGR gene and rs1800215 at the COL1A1 gene are significantly associated to POP. In the area of pregnancy, labor and delivery, the analysis confirmed a strong etiologic link between vaginal birth and symptoms of POP, with the first vaginal delivery (OR: 2.65; 95% CI: 1.81-3.88) and forceps delivery (OR: 2.51; 95% CI: 1.24-3.83) being the main determinants. Regarding age and menopause, only age was identified as a risk factor (OR : 1.102; 95% CI: 1.02-1.19) but current data do not identify postmenopausal status as being statistically associated with POP. In several animal models, there are measurable effects of pregnancy, delivery and iatrogenic menopause on the structure/function of vaginal support components, though not on the development of POP.

CONCLUSIONS

Genetics, vaginal birth and age all have a strong etiologic link to the development of POP, to which other factors may add or protect against the risk.

Impacts of external rotators and the ischiofemoral ligament on preventing excessive internal hip rotation: a cadaveric study

BACKGROUND

This study examined the biomechanics of preventing excessive internal hip joint rotation related to the hip flexion angle.

METHOD

An intramedullary nail with a circular plate equipped with a protractor was installed in the femur of nine normal hips. The circular plate was pulled by 3.15 Nm of force in the internal rotation direction. The external rotators were individually resected, finally cutting the ischiofemoral ligament. The cutting order of the external rotators differed on each side to individually determine the internal rotation resistance. The external rotators were resected from the piriformis to the obturator externus in the right hips and the reverse order in the left hips. Traction was performed after excising each muscle and ischiofemoral ligament. Measurements were taken at 0°, 30°, and 60° of hip flexion, and the differences from baseline were calculated.

RESULTS

For the right hip measurements, the piriformis and ischiofemoral ligament resection significantly differed at 0° of flexion (p = 0.02), each external rotator and the ischiofemoral ligament resections significantly differed at 30° of flexion (p < 0.01), and the ischiofemoral ligament and piriformis and inferior gemellus resections significantly differed at 60° of flexion (p = 0.04 and p = 0.02, respectively). In the left hips, the ischiofemoral ligament and obturator externus, inferior gemellus, and obturator internus resections significantly differed at 0° of flexion (p < 0.01, p < 0.01, and p = 0.01, respectively), as did each external rotator and the ischiofemoral ligament resections at 30° of flexion (p < 0.01).

CONCLUSION

The ischiofemoral ligament primarily restricted the internal rotation of the hip joint. The piriformis and obturator internus may restrict internal rotation at 0° and 60° of flexion.

Absolute and Relative Reliability of the Assessment of the Muscle Mechanical Properties of Pelvic Floor Muscles in Women with and without Urinary Incontinence

An analysis of the muscle mechanical properties (MMPs) of the pelvic floor muscles (PFMs) is relevant for understanding the physiopathology of urinary incontinence (UI). However, there is no objective and reliable methodology currently available for quantifying the MMPs of PFMs. Thus, the objective was to determine the intra-rater and inter-rater reliability of the MMPs of PFM assessment with a hand-held tonometer device, called the MyotonPRO, in young women with and without UI. Sociodemographic and pelvic floor questionnaires, plus MMPs of PFMs were assessed in 38 nulliparous women with UI and 40 matched healthy women by two trained physiotherapists on two different occasions, 48-72 h apart. Good to excellent absolute reliability was found for tone, stiffness, and decrement of both intra- and inter-rater analyses in both study groups (Intraclass Correlation Coefficient ranged from 0.75 to 0.92), with a trend of lower values for relaxation and creep. The standard error of measurement (SEM) did not achieve 10% of the mean values for any MMPs. The minimum detectable change (MDC) values were also provided for clinical applications. In conclusion, the relative reliability of tone, stiffness, and the assessment of the decrement of PFMs with MyotonPRO is good to excellent for UI and healthy women. The SEM and MDC values were acceptable for their application in clinical settings.

Systematic review of skeletal muscle passive mechanics experimental methodology

Understanding passive skeletal muscle mechanics is critical in defining structure-function relationships in skeletal muscle and ultimately understanding pathologically impaired muscle. In this systematic review, we performed an exhaustive literature search using PRISMA guidelines to quantify passive muscle mechanical properties, summarized the methods used to create these data, and make recommendations to standardize future studies. We screened over 7500 papers and found 80 papers that met the inclusion criteria. These papers reported passive muscle mechanics from single muscle fiber to whole muscle across 16 species and 54 distinct muscles. We found a wide range of methodological differences in sample selection, preparation, testing, and analysis. The systematic review revealed that passive muscle mechanics is species and scale dependent-specifically within mammals, the passive mechanics increases non-linearly with scale. However, a detailed understanding of passive mechanics is still unclear because the varied methodologies impede comparisons across studies, scales, species, and muscles. Therefore, we recommend the following: smaller scales may be maintained within storage solution prior to testing, when samples are tested statically use 2-3 min of relaxation time, stress normalization at the whole muscle level be to physiologic cross-sectional area, strain normalization be to sarcomere length when possible, and an exponential equation be used to fit the data. Additional studies using these recommendations will allow exploration of the multiscale relationship of passive force within and across species to provide the fundamental knowledge needed to improve our understanding of passive muscle mechanics.

Quantifying the Effects of Aging on Morphological and Cellular Properties of Human Female Pelvic Floor Muscles

Age-related pelvic floor muscle (PFM) dysfunction is a critical defect in the progression to pelvic floor disorders (PFDs). Despite dramatic prevalence of PFDs in older women, the underlying pathophysiology of age-related PFM dysfunction remains poorly understood. Using cadaveric specimens, we quantified aging effects on functionally relevant PFM properties and compared PFMs with the appendicular muscles from the same donors. PFMs, obturator internus, and vastus lateralis were procured from younger (N = 4) and older (N = 11) donors with known obstetrical and medical history. Our findings demonstrate that PFMs undergo degenerative, rather than atrophic, alterations. Importantly, age-related fibrotic degeneration disproportionally impacts PFMs compared to the appendicular muscles. We identified intramuscular lipid accumulation as another contributing factor to the pathological alterations of PFMs with aging. We observed a fourfold decrease in muscle stem cell (MuSC) pool of aged relative to younger PFMs, but the MuSC pool of appendicular muscles from the same older donors was only twofold lower than in younger group, although these differences were not statistically significant. Age-related degeneration appears to disproportionally impact PFMs relative to the appendicular muscles from the same donors. Knowledge of tissue- and cell-level changes in aged PFMs is essential to promote our understanding of the mechanisms governing PFM dysfunction in older women.