3D biomechanical modeling of genital prolapse and simulation of surgical treatment

Le prolapsus génital est une pathologie fonctionnelle féminine fréquente dont le retentissement sur la qualité de vie des femmes peut être important et constitue aujourd'hui un véritable enjeu de santé publique.Genital prolapse is a frequent female functional pathology that can have strong impact on quality of life; it is today a real public health issue. Surgical treatment of the various stages of cystocele is a current challenge. We developed an innovative 3D numerical model using the Finite Elements method, to enable simulation of the various surgical techniques. The model also allowed validation of our surgical hypotheses and provided some answers to outstanding questions in cystocele surgery. The first of my PhD studies allowed me to make a complete review of the anatomical pelvic organ support structures involved in prolapse, and to distinguish certain anatomic theories relating clinical expression to specific anatomic lesions. The various theories are actually quite close and complementary, but differ in terms of the mechanism implicated. The second study involved designing a 3D numerical biomechanical model of the pelvic floor, based on Finite Elements analysis coupled to dynamic MRI. The model allowed me to assess the various theories of pelvic organ suspension, and to design simulations of cystocele mobility. The model provided better understanding of the anatomic structures involved in prolapse. The third study involved designing a 3D numerical pathologic model based on data for patients with grade ≥ 3 cystocele. The model enabled analysis and assessment of the impact of the various surgical correction techniques and fixation zones on organ mobility. Although the results have not been validated clinically, the study contributed to the scientific literature on the importance of mesh reinforcement in the management of cystocele. Comparison between the various techniques (sacrocolpopexy, vaginal mesh suspension, sacrospinous fixation) using the POP-Q points found that point Ba was better corrected by sacrocolpopexy than sacrospinous fixation or vaginal mesh suspension. For sacrospinous fixation, the further it is performed from the sciatic spine, the better the apical correction of point C but the poorer the correction of point Ba. These findings could be used to improve surgical correction techniques and standardize practice. Thus, our 3D numerical cystocele model could contribute to selecting the surgical technique for correction of the cervix and anterior vaginal wall. The Finite Elements model of the pelvic system provides better understanding of the mechanisms underlying surgical correction of cystocele and the vaginal apex. It could also enable the results of prolapse surgery to be predicted, adapting technique to the individual patient by preoperative simulation. Simulation provides original and interesting information on mobility in prolapse. The present simulation results obviously need future assessment in comparison with clinical practice. In conclusion, simulation and the implementation of a 3D numerical model of pelvic mobility now allows better understanding of the mechanisms underlying pelvic statics disorder, with simulation of pathological pelvic mobility and of prolapse surgery procedures