A biomechanical model of the pelvic cavity: first steps.

The surgical treatments of genital prolapsus are still empirical and poorly valued. We plan to achieve a method for the objective assessment of the troubles of the pelvic statics and of the various surgical strategies. The methodology considers 3 axes: building a 3D mechanical model of the pelvic cavity, mechanical characterization of the concerned organic tissues, in-vivo measurement of the intravaginal pressures. The MRI images are acquired according 3 orientations (sagittal, axial and coronal); the organs (bladder, vagina and rectum) are manually outlined and their 3D shape is then rebuilt. Uniaxial tensile tests are initially developed on animal samples before being applied to peroperative human samples. In-vivo measurements of the intravaginal pressures are made thanks to a set of 8 strain gauges specially designed. We show results obtained on 2 patients with a different rank of prolapsus. These first steps will be continued by a more detailed geometry of the organs and a characterization of healthy tissues. Dynamic behaviour of the mechanical stresses will also be investigated.