Mechanical Characterization of Synthetic Mesh for Pelvic Organ Prolapse Repair

Pelvic organ prolapse (POP) is characterized by the abnormal descent of the pelvic organs into the vaginal canal. POP is associated with urinary, defacatory, and sexual dysfunction, in addition to psychological disorders including depression. Prolapse is quite common, with ~50% of women over the age of 50 exhibiting some degree of prolapse, and over 200,000 surgical repairs in the United States annually. During surgical repair, a graft is used to restore support to the vagina, re-approximating the normal anatomy. Given the high failure rate of native tissue repair, use of polypropylene mesh has become widespread. Despite the prevalence of synthetic mesh, complication rates are ~20%, with little known about its behavior following implantation. Therefore, this dissertation aims to rigorously characterize the mechanical behavior of synthetic mesh, with the goal of optimizing device design for use in the pelvic floor.\ud \ud First, micro- and macro-level deformation of mesh was assessed in response to mechanical loads using uniaxial testing and 3D reconstruction. Upon loading, mesh pores significantly deformed, yielding textile dimensions that are known to heighten the foreign body response. In addition, point loads significantly wrinkled the mesh surface, further reducing mesh dimensions and producing configurations consistent with those found clinically.\ud \ud Next, a finite element model for synthetic mesh was developed, using a novel method to allow for textile properties to be measured in-silico. This model was validated using a custom testing apparatus to simultaneously load and image transvaginal mesh products. Evaluation of mesh deformation found experimental and computational results to be similar, demonstrating the predictive capabilities of this model. The validated model was then used to examine the sensitivity of mesh behavior to variable loading conditions. Here the magnitude and orientation of tensile forces were found to significantly predict undesired deformations.\ud \ud Finally, computational mesh models were combined with MRI reconstructions of patient specific anatomy to simulate the development of prolapse and mesh repair. Again, mesh pores experienced significant deformation upon anatomical fixation, corresponding with clinical sites of exposure and pain. In total, this dissertation provides a tool for the evaluation and optimization of synthetic mesh devices prior to implantation and pre-surgical evaluation of mesh procedures