![]() ![]() We used an explicit finite element (FE) formulation, better known as the Total Lagrangian Explicit Dynamics (TLED) method by Miller et al. In this paper, we focus on the technical side of the R&D by describing the methodology we used to model the mechanical contact problem of physiological childbirth on computer. Before such a sophisticated predictive simulator can be developed, the ‘normal’ interaction between fetus and maternal pelvic anatomy-nowadays referred to as physiological childbirth-has to be realistically modelled and simulated first. This is of great clinical importance as it would allow clinicians to plan ahead, for example, to decide on an elective Caesarean Section (CS) if the simulation returns a high risk score on the occurrence of SD. In the longer run, the aim of the project is to create a patient-specific ‘virtual reality’ (VR) childbirth simulator capable of assessing the likelihood of normal and, more importantly, abnormal outcomes for individual cases prior to the actual event. ![]() ![]() Unfavourable presentations such as brow and face. The possibility of labour coming to a halt because the fetal shoulder impacts with the bony pelvis known as shoulder dystocia (SD) The adverse effect on pelvic floor muscles when overstretched and potentially resulting in incontinence following childbirth The ‘cardinal movements’ (CMs) of the fetal head which occur during physiological birth Footnote 1 From a purely physical perspective, this constitutes a mechanical contact problem which lies at the basis of various phenomena including: More specifically, during the second stage of labour, the fetal head comes into contact with the maternal bony pelvis and pelvic floor muscles due to the expulsive forces aiming to expel the fetus from the womb. the fetus and the maternal abdominal and pelvic anatomy. The biomechanical process of human childbirth involves intricate interactions between the two main agents, i.e. The results confirm the potential of the simulator as a predictive tool for problematic childbirths subject to patient-specific adaptations. Following a series of simulations, taking variations in the shape and size of the geometric models into account, we consistently observed the cardinal movements in the simulator just as they happen in physiological childbirth. Realistic mesh models of the fetus, bony pelvis and pelvic floor muscles were subjected to the intra-uterine expulsion forces which aim to propel the virtual fetus through the virtual birth canal. The experimental section covers first a number of validation experiments on simple contact mechanical problems which is followed by the main experiment of running a virtual reality childbirth. The paper describes the underlying mathematics and algorithms of the solution and their combination into a computer-based implementation. The underpinning science is based on two numerical algorithms including the total Lagrangian explicit dynamics method to calculate soft tissue deformation and the partial Dirichlet–Neumann contact method to calculate the mechanical contact interaction between the fetal head and maternal pelvic anatomy. The research presented in this paper introduces a virtual reality-based simulation of physiological childbirth. The mentum (chin) is the presenting part.During physiological or ‘natural’ childbirth, the fetal head follows a distinct motion pattern-often referred to as the cardinal movements or ‘mechanisms’ of childbirth-due to the biomechanical interaction between the fetus and maternal pelvic anatomy. The brow or forehead is the presenting part. The top of the head is the presenting part. This is an uncommon fetal position and a vaginal birth is unlikely.Ĭommonly, this skull diameter is too large to pass through the pelvis. Many fetuses assume this attitude early in labor but convert to complete flexion as labor progresses. This position is commonly called the fetal position. The back is usually arched, which increases the degree of hyperextension. In complete extension, the head and neck of the fetus are hyperextended and the occiput touches the fetus’s upper back. In partial extension, the head of the fetus is extended, with the head pushed slightly backward so that the brow becomes the first part of the fetus to pass through the pelvis during birth. Moderate flexion (aka military position or sinciput), the head of the fetus is slightly flexed but held straighter than in complete flexion. In complete flexion, the head of the fetus is tucked down onto the chest, with the chin touching the sternum. ![]()
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