During vaginal delivery, several maternal positions can be adopted to facilitate the labor process, although there is limited evidence to support the most ideal position. This work aims at contributing to a better knowledge associated the biomechanics of different birthing positions and their consequences. A biomechanical model composed by the pelvic floor muscles attached to the bones, and a fetus head was used to simulate vaginal deliveries. Two birthing positions were mimicked: non-flexible and flexible sacrum positions. In the former, a 6 mm pubic symphysis widening and a coccyx rotation of 3.6º occurred. In contrast, a lower pubic symphysis widening occurred (3 mm) in the flexible sacrum model, since a higher coccyx rotation was observed. Globally, it can be concluded that positions with the weight off the sacrum appear to be more beneficial for the pelvic girdle bones of the mother.

Abstract Background Capsule endoscopy (CE) plays a central role in the management of patients with suspected or known Crohn’s disease (CD). It is indicated for the diagnosis, classification, monitoring of the response to treatment, and prognostic prediction. In 2017, PillCam™ Crohn’s Capsule (PCC) was introduced. It has demonstrated greater accuracy in detecting and evaluating the extent of lesions in these patients. However, this new tool produces thousands of images, whose revision is time-consuming and prone to errors, since lesions can be restricted to a small number of images. In the last decade, several Artificial Intelligence (AI) algorithms were developed, and demonstrated potential to mitigate some of the drawbacks of CE. Among AI tools, Convolutional Neural Networks (CNN) display the best performance for imagery analysis. This study aims to develop an AI algorithm based on an CNN for the automatic detection of ulcers and erosions of the small intestine and colon in PCC images. Methods A total of 8 085 PCC images were extracted from a single tertiary centre between 2017–2020. This pool of images was constituted by 2 855 images depicting ulcers, 1 975 erosions; the remaining with normal enteric and colonic mucosa. For the automatic identification of these findings, this pool of images was split into training and validation datasets. A CNN model with transfer learning using tensorflow and keras tools was constructed. The performance of the network was subsequently assessed in an independent test set. Results After optimizing the different layers of the CNN, our model was able to detect and distinguish small intestinal or colonic erosions or ulcers with a sensitivity and specificity of 90.0% and 96.0%, respectively. The precision and accuracy of this model were 97.1% and 92.4%, respectively (Figure 1). Particularly, the CNN detected ulcers with a sensitivity of 83% and specificity of 98%, and erosions with sensitivity and specificity of 91% and 93%, respectively. Conclusion Our group developed, for the first time, a CNN capable of automatically detecting ulcers and erosions of the small intestine and colon in PCC images with high sensitivity and specificity. These findings are extremely important since they pave the way for the development of systems for the automatic detection of clinically significant lesions, optimizing diagnostic performance and efficiency of monitoring CD activity.

The present study aims to compare spinal stability after two different minimally invasive techniques, the lateral lumbar interbody fusion (LLIF) and the transforaminal lumbar interbody fusion (TLIF) approaches. Two nonlinear three-dimensional finite element (FE) models of the L4-L5 functional spinal unit (FSU) were subjected to the loads that usually act on the lumbar spine. Findings show that the LLIF approach yields better results for torsion load case, due to the larger surface area of the implant. For extension, flexion and lateral bending loads, the TLIF approach presents smaller displacements probably due to the anterior placement of the cage and to the smaller damaged area of the annulus fibrosus.

There are various techniques to obtain lumbar interbody fusion (LIF) at L5-S1 functional unit (FSU) level. This paper presents a finite element analysis to investigate the biomechanical changes caused by transforaminal lumbar interbody fusion (TLIF) at the L5-S1 FSU level. The information collected can be used to choose the best chirurgical treatment to solve several pathologies. This approach places the implant into the anterior portion of the intervertebral disc space, which stabilizes the flexion–extension movement across the operated level. Numerical results of segmental motion show that torsion and extension load cases yield the highest rotation angles during the early and long-term postoperative phases, respectively. Furthermore, a decrease in autogenous bone graft volume results in a reduction of displacements and rotation angles.

Hypothesis / aims of study The female pelvic floor is a support structure that includes fascia, ligaments and muscles (PFM) of the urogenital region. It extends from the symphysis pubis to the coccyx, and comprises the levator hiatus for the passage of the urethra, vagina and rectum. The PFM include the coccygeus, ileococcygeuos, pubococcygeus, and puborectalis muscles, the latter two frequently referred together as the pubovisceralis muscle (PVM) [1]. The impairment of the pelvic floor muscles (PFM) is a major ingredient to develop urinary incontinence (IU) and/or pelvic organ prolapse (POP) (Schwertner-Tiepelmann et al., 2012). These disorders may result from changes in the biomechanical properties of the supportive structures that occur from weakness or impairment of muscles or ligaments, or alterations in the stiffness of the pelvic fascia associated with the risk factors age, hormonal changes, among others [2]. The related conditions have been studied through imaging techniques and experimental in vitro studies, evaluating biomechanical properties of the pelvic ligaments, vaginal tissue and levator ani (LA) muscle. To obtain these biomechanical properties, acquired tissue during surgery or from female cadaver has been tested using different techniques. However, these collected tissues are frequently afflicted in clinical environment, and consequently, the comparison to in vivo healthy tissues is difficult. Hence, these studies show the nonlinear mechanical behavior, but they do not reflect the natural conditions for in vivo muscle behavior in the pelvis. In this context, the computational analysis coupled with in vivo biomechanical properties may help to correctly reproduce the biomechanical behavior of the PFM.

The cervical spine is one of the most complex structures of the human skeleton. The knowledge of the cervical spine kinematics is a very important tool for many clinical applications such as diagnosis, treatment and surgical interventions and for the development of new spinal implants. The finite element method (FEM) is a well-known and widely used numerical method to simulate structural behaviour of spine. The main goal of this paper was to create a 3D finite element model of cervical segment C4-C5-C6 using computed tomography (CT) data, in order to analyse and compare anterior cervical fusion and / or posterior cervical fusion as possible treatments for a fracture of type C2.2 according to the AO spine classification. As expected, with this study it was concluded that the anterior and posterior cervical fusion provides the best results when compared to the other types of cervical fusion studied.

Modeling the events that take place during childbirth requires an integration of morphological features, tissue characteristics, and prediction of the most probable fetal movements according to the inputs submitted to the computational model. The choice of the material properties and constitutive models affect the outputs, and the challenge still points out to how to mathematically describe the pelvic soft tissues if experimental proof is not possible. Several authors explored the modeling of vaginal delivery by focusing on different aspects: the maternal pelvic bones, the fetus position, and head molding, but most of them focused on the effects of vaginal delivery on the pelvic floor muscles. The present chapter reviews the events that occur during childbirth, to better illustrate the features described in a computational reproduction of labor. The focus is set on the results from different numerical simulation approaches, and on the biomechanical analysis of the pelvic floor muscles and fetal head passage.

The group of levator ani muscles is of the most importance in the support of the pelvic organs and urethral closure by resisting the downward forces imposed to the organs and to the pelvic floor whenever the intra-abdominal pressure is increased. Deficient muscular contraction, which may be caused by direct neuromuscular damage can result in major defecation disorders or vesico-uterine prolapses. It is not possible to obtain material parameters from live subjects, to use in numerical simulations of the pelvic floor muscles. In this work, an optimization algorithm was implemented in order to obtain the in vivo material parameters for different hyperelastic constitutive models. The optimization algorithm uses the python language to couple the Matlab (R) and Abaqus (R) software. The Powell's method was used for the optimization part of the algorithm. The Inverse Method and an optimization algorithm were used, and the material parameters obtained were consistent with the literature.

The objective of this work is to study the influence of different fluids of the tympanic cavity into the biomechanical behavior of the middle ear. The 3 D computer model of the tympanic ossicular chain was built using images from computed tomography (CT). After construction of the tympanic ossicular chain model, it was adapted the simulation by placing the passage to the external auditory canal and to the tympanic cavity.The discretization of the model was made using the finite element method based on ABAQUS software. The mechanical properties were extracted from previous works. The umbo and the stapes footplate displacements, for a sound pressure level of 105 dB applied in tympanic membrane were obtained, corn paring the tympanic ossicular chain and the different levels of external and internal pressure in the middle ear (liquid and air). The results demonstrate that the biomechanical behavior of the middle ear is different for different levels of pressure tested in this model. When using liquid, displacements are of lower amplitude when compared with the results obtained with air. (C) 2014 CIMNE (Universitat Politecnica de Catalunya). Published by Elsevier Espana, S.L.U.

Otosclerosis is one of the causes of conductive hearing loss in adults. It affects both sexes, although there is a greater predominance in women. The ratio is 1:2 (man:woman). There is even a deterioration of hearing with the pregnancy. In this work, we have found strong supporting evidence of this, making a clinical study with 53 women, where 35 reported having worsening of the hearing with pregnancy and only 18 did not relate auditory worsening with pregnancy. This clinical study was complemented with a numerical study where we can verify the differences in stapes footplate displacements, comparing a model representative of the normal ear with different stiffness of annular ligament of stapes, simulating otosclerosis.

Excessive bladder neck displacement is a common feature in pelvic floor dysfunctions, such as stress urinary incontinence. The objective of this work is to develop a female pelvic computational model, and validate it through measuring the bladder neck movement during Valsalva maneuver and comparing it with published values. Magnetic Resonance Images (MRI) of a healthy female were used to build a female pelvic cavity model. Appropriate material properties and constitutive models were defined for each one of its structures. A simulation of the Valsalva maneuver revealed a bladder neck displacement of 5.0 mm. Numerical simulation of a female pelvic model could predict bladder neck displacement during Valsalva maneuver. Results were similar to those published in the literature, validating the developed model.

The human knee, which is a mobile pivotal condylar join that permits flexion, extension and a slight internal and external rotation, is the largest join in the human body. The ligaments of the knee provide stability, limit the knee movement and help to protect the articular capsule. The anterior cruciate ligament (ACL), one of the four main ligaments of the knee, is extremely important in the stabilization of the knee when turning or planting. The rupture of the ACL is one of the most common knee injuries, where the surgical procedure for its reconstruction is done through arthroscopy, a low-invasive surgery performed using a small camera, an arthroscope. In case of injury an orthopedist surgeon evaluates the ligament damage, and thus he chooses the patient bone site to drill in order to insert a previously harvested tissue that will substitute the damaged ACL. The success of this surgical procedure depends mainly on the surgeon ability and skill to drill accurately the holes in the bone, since non-anatomic bone tunnel misplacement has been reported as the most common cause of ACL reconstruction failure. With this, and, using a patient specific instrumentation (PSI) systems, that is being developed as a replacement for traditional instrumentation in total knee arthroplasty (TKA), this study intends to adapt this in-developing technology to ACL repair surgery. Using the PSI concept to precisely locate the femoral tunnel location during the procedure, a guide item will be generated using 3D anatomic information gathered from magnetic resonance imaging (MRI) and/or computed tomography (CT) imagery. In the end, the present proposal aims to deliver a prototype for a universal surgical guide, capable to assist low-invasive knee surgeries for the ACL reconstruction. Thus, in the course of the reconstruction surgery, this universal surgical guide will permit to mark the exact location of the bone drill, as planned in the pre-surgical study.

The pelvic floor dysfunction includes common conditions like urinary incontinence and pelvic organ prolapse. The pelvic floor has a relevant role on organ support and, therefore, pelvic floor biomechanical models play an important role on the clinical and research settings. Magnetic Resonance images and the Finite Element Method are often used in the modeling process. In this work, the direction of the fibers of the pubovisceral muscle were compared by using Magnetic Resonance Imaging-based tractography and the Maximum Principal Stress Lines obtained by numerical simulation. Mean absolute and mean percentage of relative error were assessed. There were discrepancies on the muscle fiber direction obtained from both methodologies. The insertion areas of the muscle presented increased error when compared to the central area, where the pubovisceral muscle surrounds the rectum. The methodologies for numerical simulation may gain from information provided by the tractography.