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Figure la-b: Female pelvis. a) Plastinated transverse section of the pelvis at the level of coccygis. Slice thickness 1.6 mm. b) Corresponding detail of the marked area on fig 1ashowing the levatorani and its components.
Source publication
Background: The structures of the pelvic floor are clinically important but difficult to assess. To facilitate the understanding of the complicated pelvic floor
Citations
... The ASC volume was obtained as a sum of all marked individual voxels. Segmentation was performed by a single trained operator (PF) [18,19]. In order to evaluate whether segmentation results obtained from axial and coronal planes were comparable, a subset of thirteen cases was segmented in both planes. ...
Background/Purpose
The anal sphincter complex (ASC) plays a key-role in continence and is often dysfunctional in infants born with anorectal malformations (ARM). The ASC is well depicted by magnetic resonance (MR) imaging but volumetric reference data are lacking in infants. Thus, we tested the feasibility of MR-based ASC volumetry, collected reference data, and compared them with cases of favourable prognosis and unfavourable prognosis (as defined by the type of ARM).
Methods
We determined ASC volume on T2-weighted MR-images of seventy-six infants (ARM n = 33; controls n = 43) by manual segmentation. Inter-operator agreement was assessed by intraclass-correlation coefficient. Linear regression was used to establish weight-dependent reference data. Observed-to-expected ASC volumes of patients with unfavourable and favourable prognosis were compared (unpaired t-test).
Results
ASC volumetry was feasible in all cases. Patients with ARM had low ‘observed-to-expected’ ASC volume (-18.1%; p = 0.006). ‘Observed-to-expected’ ASC volume differed significantly between patients with favourable and unfavourable prognosis (p < 0.001).
Conclusion
We confirmed the feasibility of MRI-based ASC volumetry and provided initial reference data for infants. Although ASC volumes were lowest in infants with ARM of unfavourable prognosis for fecal continence, the value of ASC volume as prognostic parameter remains to be determined.
... Nonetheless, fetuses are mostly "floating" in open space above the maternal pelvis in existing models, due to the lack of maternal soft tissues. Despite the fact that geometrical models of maternal pelvic floor and pelvic organs have been developed in numerous studies [76][77][78][79][80][81], childbirth computational models rarely include structures other than levator ani muscles. This leads to inaccurate estimations of the resistive force that the fetal model experiences and requires an imposed trajectory and movements to obtain stable fetal passage through the pelvis. ...
The biomechanical process of childbirth is necessary to usher in new lives – but it can also result in trauma. This physically intense process can put both the mother and the child at risk of injuries and complications that have life-long impact. Computational models, as a powerful tool to simulate and explore complex phenomena, have been used to improve our understanding of childbirth processes and related injuries since the 1990s. The goal of this paper is to review and summarize the breadth and current state of the computational models of childbirth in the literature – focusing on those that investigate the mechanical process and effects. We first summarize the state of critical characteristics that have been included in computational models of childbirth (i.e., maternal anatomy, fetal anatomy, cardinal movements, and maternal soft tissue mechanical behavior). We then delve into the findings of the past studies of birth processes and mechanical injuries in an effort to bridge the gap between the theoretical, numerical assessment and the empirical, clinical observations and practices. These findings are from applications of childbirth computational models in four areas: (1) the process of childbirth itself, (2) maternal injuries, (3) fetal injuries, and (4) protective measures employed by clinicians during delivery. Finally, we identify some of the challenges that computational models still face and suggest future directions through which more biofidelic simulations of childbirth might be achieved, with the goal that advancing models may provide more efficient and accurate, patient-specific assessment to support future clinical decision-making.
... The three-dimensional biomechanical model of the female pelvis involved in this paper is adopted from our previous studies Bhattarai and Staat 2018a) and has been constructed from a pelvis of a 70-year-old cadaver based on the standard ultra-thin slice plastination technique ( Sora et al. 2012;Feil and Sora 2014). The detailed history of the pelvic floor pathologies of the female cadaver is unknown for these studies. ...
Minimally invasive surgery such as laparoscopic sacrocolpopexy, pectopexy and cervicosacropexy are widely performed for the treatment of the vaginal vault/cuff prolapse using prosthetic mesh implants to strengthen lax apical ligaments. Depending on the patient’s anatomy and the surgeon’s preference, implants of different shapes, pore architectures and polymers can be selected. In this article, a 3D model of the pelvis was built and the pectopexy technique was reproduced. The finite element model of the textile implant was sutured to the cervical stump with a bilateral fixation to the iliopectineal ligament on either side of the pelvic walls. Pelvic soft tissues and prosthetic implants were modelled as hyperelastic and linearly elastic orthotropic materials, respectively. Numerical simulations were performed after surgery at rest and during Valsalva manoeuvre. The positions and the orientation of the vagina, during increased abdominal pressure were calculated in relation to the pubococcygeal line (PCL). We found from our simulation-model that the structure of the DynaMesh®-PRP Soft (17.18 mm above PCL line) provides better support to the vaginal cuff compared to GYNEMESH (11.95 mm) and ARTISYN (6.72 mm). And the treatment with, the stiffer DynaMesh seems to provide better urethral axis (24°) than the flexible Ethicon meshes (28.5° and 29°).
... Plastinated material can be used effectively for computerised three-dimensional reconstruction ( Figure 5). Computer models and animations of anatomical features are becoming increasingly attractive as a means to communicate complex spatial relationships and concepts effectively (Dev et al., 2002;Feil & Sora, 2014). Although many educational animations are based on artistic renderings (Gould, 2001;Habbal & Harris, 1995;Johnson & Whitaker, 1995), more recent applications are using virtual representations derived from actual cadaveric material (Lozanoff et al., 2003;Neider, Scott, & Anderson, 2000). ...
Over the last four decades, plastination has been one of the best processes of preservation for organic tissue. In this process, water and lipids in biological tissues are replaced by polymers (silicone, epoxy, polyester) which are hardened, resulting in dry, odourless and durable specimens. Nowadays, after more than 40 years of its development, plastination is applied in more than 400 departments of anatomy, pathology, forensic sciences and biology all over the world. The most known polymers used in plastination are silicone (S10), epoxy (E12) and polyester (P40). The key element in plastination is the impregnation stage, and therefore depending on the polymer that is used, the optical quality of specimens differs. The S10 silicone technique is the most common technique used in plastination. Specimens can be used, especially in teaching, as they are easy to handle and display a realistic topography. Plastinated silicone specimens are used for displaying whole bodies, or body parts for exhibition. Transparent tissue sections, with a thickness between 1 and 4 mm, are usually produced by using epoxy (E12) or polyester (P40) polymer. These sections can be used to study both macroscopic and microscopic structures. Compared with the usual methods of dissection or corrosion, plastinated slices have the advantage of not destroying or altering the spatial relationships of structures. Plastination can be used as a teaching and research tool. Besides the teaching and scientific sector, plastination becomes a common resource for exhibitions, as worldwide more and more exhibitions use plastinated specimens.
... Cutting epoxy blocks with a diamond band saw yields thin parallel slices without side deviations even if metal or other hard material is cut in an oblique way. Therefore the method has been used for 3D reconstructions (Feil & Sora, 2014;Sha et al., 2001;Sora, Genser-Strobl, Radu, & Lozanoff, 2007). While series of sections were well-suitable for research purposes, their use in teaching and museum exhibition showed limitations. ...
With classical sheet plastination techniques such as E12, the level and thickness of the freeze‐cut sections decide on what is visible in the final sheet plastinated sections. However, there are other plastination techniques available where we can look for specific anatomical structures through the thickness of the tissue. These techniques include sectioning and grinding of plastinated tissue blocks or thick slices. The ultra‐thin E12 technique, unlike the classic E12 technique, starts with the plastination of a large tissue block. High temperatures (30–60°C) facilitate the vacuum‐forced impregnation by decreasing the viscosity of the E12 and increasing the vapour pressure of the intermediary solvent. By sectioning the cured tissue block with a diamond band saw plastinated sections with a thickness of <300 μm can be obtained. The thickness of plastinated sections can be further reduced by grinding. Resulting sections of <100 µm are suitable for histological staining and microscopic studies. Anatomical structures of interest in thick plastinate slices can be followed by variable manual grinding in a method referred to as Tissue Tracing Technique (TTT). In addition, the tissue thickness can be adapted to the transparency or darkness of tissue types in different regions of the same plastinated section. The aim of this study was to evaluate the advantages of techniques based on sectioning and grinding of plastinated tissue (E12 ultra‐thin and TTT) compared to conventional sheet‐forming techniques (E12).
... Three-dimensional computational models constructed from medical imaging in living patients and plastination techniques in cadaver samples have been used as an powerful tool to study different anatomical and clinical questions. Offered a free selection of imaging plane (Tan et al. [298]), most of models are reconstructed using MRI (Chen et al. [58], Luo et al. [179], Noakes et al. [210], Otcenasek et al. [218], Peng et al. [230]) and quite few using X-rays (Bush et al. [47]) and plastination (Beyersdorff et al. [23], Bhattarai et al. [24], Feil and Sora [92] [280]), normal defecatory mechanisms (Noakes [209], Noakes et al. [210]), sports (Roza et al. [263]) and ligament impairment (Brandão et al. [40]). Although, such patient specific models are of huge benefit, but are limited by an incomplete anatomical structures (Rubod et al. [266]), idealised boundary conditions (Chen et al. [58], Luo et al. [179], Noakes et al. [210]) and simplified tissue mechanics (Noakes et al. [210], Peng et al. [230]) that widely vary the quantitative results from one study to another. ...
... The female pelvis is separated from a 70 year old female cadaver specimen, which is a part of the human donation program of the Medical University of Vienna (Feil and Sora [92]). The Ethical Committee of the university provided approval for using the pelvis for 3D reconstruction: EK Nr: 1191/2011. ...
... 5: a) Computer model of the female pelvic floor including bony pelvis, pelvic viscera, muscles, ligaments and nerves.(Bhattarai et al. [24], Feil and Sora[92]). ...
Female pelvic floor dysfunctions (PFDs) such as incontinence and prolapse are observed
in multiparous elderly females caused by denervation injuries during childbirth and progressive tissue remodeling after menopause. With continuously increasing average life
expectancy, these disorders have become an important public health issue that require high costs for the treatment and a standardized study. Minimally invasive surgery has become a more frequent repair procedure for which more than 20 million implants are implanted worldwide every year. However, serious postoperative mesh relative complications are reported.
This thesis reviews the static, functional and dynamic anatomy of the female pelvic floor.
A detail methodology to construct a realistic computer model from sheet plastination of
a female cadaver pelvic floor has been described. Based on the published literature and
multi-disciplinary communication with surgeons and urologist, a most complete form of
3D finite element (FE) model has been constructed, which considers smoothed NURBS
based surfaces for frictionless contacts between organs and internal self-contact of the
hollow organs. Further, an isotropic, hyperelastic, incompressible multiscale modeling of
the soft connective tissues is adopted. In addition, transversely isotropic and non-linear
Humphrey’s constitutive model has been implemented to describe the passive stretching
of the pelvic skeletal muscle without neural excitation. Similarly, for the experimented
surgical meshes with different pore characteristics and stress-strain curves, linearly elastic
orthotropic and non-linear hyperelastic models are fitted and used in the numerical study.
Various FE analyses are performed to investigate pathophysiological situations and surgical treatments using mesh implants to compare their biofunctionality and to optimize
the preferred surgery. Hence, the presented models and the modeling approaches included
in this thesis facilitate the work of surgeons and urologists by a biomechanical study of
female PFDs.
... A three dimensional biomechanical model of the female pelvic floor was constructed from a 70-year old female cadaver pelvis based on the standard ultra-thin slice plastination technique [11,44]. Slices of 1.5 mm thickness were cut from the frozen block of the pelvis which were later submerged into successive baths of acetone and lipid remover, methylene chloride (MeCl) for dehydration and to free the tissue fat, respectively. ...
... Once all contours were traced and outlined layer by layer, for example green curves on rectal cross-section along entire rectum length in Fig. 1a, the reconstruction was rendered and visualized as a 3D model/geometry as shown in Fig. 1b These measurements were compared with the anatomical literatures and verified for computational purpose. The detailed methodology of creating the computer model from the plastinated slices has been described in [2,11,44]. ...
... a) Epoxy (E12) slice of the female pelvis in WinSURF software (2D tool)[11], b) three dimensional computer model constructed using WinSURF software (3D tool) with a horizontal gray slice plane at the level of the slice on the left. U = Urethra; V = Vagina; R = Rectum. ...
Particularly multiparous elderly women may suffer from vaginal vault prolapse after hysterectomy due to weak support from lax apical ligaments. A decreased amount of estrogen and progesterone in older age is assumed to remodel the collagen thereby reducing tissue stiffness. Sacrocolpopexy is either performed as open or laparoscopic surgery using prosthetic mesh implants to substitute lax ligaments. Y-shaped mesh models (DynaMesh, Gynemesh, and Ultrapro) are implanted in a 3D female pelvic floor finite element model in the extraperitoneal space from the vaginal cuff to the first sacral (S1) bone below promontory. Numerical simulations are conducted during Valsalva maneuver with weakened tissues modeled by reduced tissue stiffness. Tissues are modeled as incompressible, isotropic hyperelastic materials whereas the meshes are modeled either as orthotropic linear elastic or as isotropic hyperlastic materials. The positions of the vaginal cuff and the bladder base are calculated from the pubococcygeal line for female pelvic floor at rest, for prolapse and after repair using the three meshes. Due to mesh mechanics and mesh pore deformation along the loaded direction, the DynaMesh with regular rectangular mesh pores is found to provide better mechanical support to the organs than the Gynemesh and the Ultrapro with irregular hexagonal mesh pores.
... A three dimensional biomechanical model of the female pelvic floor was constructed from a pelvis of a 70-year old cadaver based on the standard ultra-thin slice plastination technique [8], [9]. Slices of 1.5 mm thickness cut from the frozen block of the pelvis were dehydrated, fat freed and hardened to construct high quality and perfectly transparent epoxy (E12) slices (Figure 2a). ...
... The reconstruction was rendered and visualized as a 3D model ( Figure 2b) and subsequently transformed into the .OBJ format. The UTHSCSA (University of Texas Health Science Center in San Antonio) IMAGE TOOL v.2.0 3 was used to morphological measure the pelvic structures and distance between them [8]. ...
... : a) Epoxy (E12) slice number 7 of the female pelvis in WinSURF software (2D tool)[8], b) 3D computer model constructed using WinSURF software (3D tool) with a gray horizontal plane at the level of the 2D slice number 7 on the left. U = Urethra (green); V = Vagina (red); R = Rectum (pink). ...
The vaginal prolapse after hysterectomy (removal of the uterus) is often associated with the prolapse of the vaginal vault, rectum, bladder, urethra or small bowel. Minimally
invasive surgery such as laparoscopic sacrocolpopexy and pectopexy are widely performed for the treatment of the vaginal prolapse with weakly supported vaginal vault after hysterectomy using prosthetic mesh implants to support (or strengthen) lax apical ligaments. Implants of different shape, size and polymers are selected depending on the patient’s anatomy and the surgeon’s preference. In this computational study on pectopexy, DynaMesh®-PRP soft, GYNECARE GYNEMESH® PS Nonabsorbable PROLENE® soft and Ultrapro® are tested in a 3D finite element model of the female pelvic floor. The mesh model is implanted into the extraperitoneal space and sutured to the vaginal stump with a bilateral fixation to the iliopectineal ligament at both sides. Numerical simulations are conducted at rest, after surgery and during Valsalva maneuver with weakened tissues modeled by reduced tissue stiffness. Tissues and prosthetic meshes are modeled as incompressible, isotropic hyperelastic materials. The positions of the organs are calculated with respect to the pubococcygeal line (PCL) for female pelvic floor at rest, after repair and during Valsalva maneuver using the three meshes.
... A three-dimensional biomechanical model of the female pelvic floor was reconstructed from a 70-year-old female cadaver specimen with no known history of pelvic pathology. The detailed methodology of creating the computer model of the internal morphology from the plastinated slices has been described in [24,28,29]. Using the ultra-thin E12 sheet plastination technique (Figure 1(a)), the visualization model ( Figure 1(b)) is well suited to map the pelvic floor anatomy into a finite element model for biomechanical analysis. ...
After menopause, decreased levels of estrogen and progesterone remodel the collagen of the soft tissues thereby reducing their stiffness. Stress urinary incontinence is associated with involuntary urine leakage due to pathological movement of the pelvic organs resulting from lax suspension system, fasciae, and ligaments. This study compares the changes in the orientation and position of the female pelvic organs due to weakened fasciae, ligaments, and their combined laxity. A mixture theory weighted by respective volume fraction of elastin-collagen fibre compound (5%), adipose tissue (85%), and smooth muscle (5%) is adopted to characterize the mechanical behaviour of the fascia. The load carrying response (other than the functional response to the pelvic organs) of each fascia component, pelvic organs, muscles, and ligaments are assumed to be isotropic, hyperelastic, and incompressible. Finite element simulations are conducted during Valsalva manoeuvre with weakened tissues modelled by reduced tissue stiffness. A significant dislocation of the urethrovesical junction is observed due to weakness of the fascia (13.89 mm) compared to the ligaments (5.47 mm). The dynamics of the pelvic floor observed in this study during Valsalva manoeuvre is associated with urethral-bladder hypermobility, greater levator plate angulation, and positive Q-tip test which are observed in incontinent females.
... Since this is the first attempt at manual segmentation of the PRM on 3D ultrasound, the results can be compared only with segmentation results of magnetic resonance imaging or cadaver studies. The segmentation results of the PRM obtained in such studies 5,[23][24][25][26][27] show very similar shapes to the those obtained in the current study, an example of which is shown in Figure 3. However, some of these studies 5,24,26 show that there is a thin layer of muscle fibers from other pelvic floor muscles running at the hiatal side of the PRM. ...
Objectives:
The introduction of 3D analysis of the puborectalis muscle, for diagnostic purposes, into daily practice is hindered by the need for appropriate training of the observers. Automatic 3D segmentation of the puborectalis muscle in 3D transperineal ultrasound may aid to its adaption in clinical practice.
Method:
A manual 3D segmentation protocol was developed to segment the puborectalis muscle. The data of 20 women, in their first trimester of pregnancy, was used to validate the reproducibility of this protocol. For automatic segmentation, active appearance models of the puborectalis muscle were developed. Those models were trained using manual segmentation data of 50 women. The performance of both manual and automatic segmentation was analyzed by measuring the overlap and distance between the segmentations. Also, the interclass correlation coefficients and their 95% confidence intervals were determined for mean echogenicity and volume of the puborectalis muscle.
Results:
The ICC values of mean echogenicity (0.968-0.991) and volume (0.626-0.910) are good to very good for both automatic and manual segmentation. The results of overlap and distance for manual segmentation are as expected, showing only few pixels (2-3) mismatch on average and a reasonable overlap. Based on overlap and distance 5 mismatches in automatic segmentation were detected, resulting in an automatic segmentation a success rate of 90%.
Conclusions:
In conclusion, this study presents a reliable manual and automatic 3D segmentation of the puborectalis muscle. This will facilitate future investigation of the puborectalis muscle. It also allows for reliable measurements of clinically potentially valuable parameters like mean echogenicity.
