[Mechanical characteristics of the human bladder wall and application of the results in a finite elements model to study the pelvic floor].
AIM: There is no radiological method capable of providing a real-time, dynamic 3D illustration of the pelvic organs and supporting structures during stress, physiological regressions and pathological alterations. This paper describes the determination of the mechanical characteristics of the human bladder, the application of the results in a numerical 3D finite elements model of the pelvis and the processing of the model in the presence or absence of urethro-pelvic and pubo-vescical ligaments supporting the pelvis. METHODS: A 3D numerical finite element model of the human pelvis has been realised starting from CT image and Mimics (Materialise), Rhinoceros (Robert Mc Neel and Associates), Patran (MSC) e Marc (MSC) programs. The mechanical characteristic of human bladder specimen have been studied in vitro drawn up from human bladder removed for neoplasia. Results have been introduced in a numeric model. After the definition of bond and load applied, we made the simulation and numerical structural analysis with and without some ligaments that link pelvic fascia and urethra at the pubis. RESULTS: The study of mechanical data of bladder reports structural differences between lateral wall, trigone wall and anterior wall in correlation to the topographical disposition of fibres of detrusor and its thickness. Dynamics investigation performed in the absence of cervical urethra ligaments of suspension and pelvic fascia showed that the anatomical deflections of pelvic fascia modified the distributions of loads toward centripetal deviation, stressing even more the perineal area and the sphincter tract. CONCLUSIONS: The study shows that trigone is the area with the greatest stiffness in comparison with other areas of the bladder and that it has the greatest strength to tensile loads. This study has shown that pelvic fascia, urethropelvic and pubovescical ligaments are cardinal supports that cannot be neglected in a dynamic numerical analysis. Dynamic simulation of the model in the absence of the ligaments confirms the role of surgical techniques used for their reconstruction following their section during radical surgery.