Virtual modeling of a female pelvic floor and hypothesis for simulating biomechanical behavior during natural delivery

摘要

The study of the mechanical behavior of the muscles constituting the pelvic floor is a challenge that demands multidisciplinary efforts. To achieve biomechanical simulation a representative geometric model of the related anatomy and hypotheses for a simplified study involving in a natural delivery process are demanded. There are many muscles included in the pelvic floor region and one of the first simplifications is the choice of the most affected muscle due to delivery. This selection was made based in MRI (Magnetic Resonance Imaging) examination data of a female volunteer with normal anatomy. The MRI images were segmented using InVesalius in order to achieve a 3D surface model. This file represents a very noisy image, with excessive detail, which can be simplified in a controlled way using BioCAD approach, developed at DT3D/CTI-Brazil. Starting from it, a computational simulation can be carried out in order to represent virtually the mechanical phenomena related to the child natural delivery, providing information for the understanding of post pregnancy and even natural changes related to it. Despite the fact that the main information to obtain such model is usually available from three dimensional medical examination data, it is not simple to use these data and even more difficult to hold all the information together inside an engineering useful model. Much of the heavy work to achieve a very good representation of an anatomical structure is related to image processing applications, which are responsible for providing filters and features to separate, in the front, signal from noise on the raw image. One of the main parts of this work lies on the achievement of such 3D geometrical model, in order to have a reliable reference from where the virtual modeling and biomechanical simulations starts. Once the appropriated 3D geometrical model of the pelvic floor was available, it was started the 3D finite elements model, in order to simulate a study case related to the child natural delivery, considering the head of the child as a perfect sphere and all the material properties found in literature. The final result showed the predicted displacement of the sphere considered as the child head and the related deformation of the pelvic floor muscle, showing the main stressed regions.