| Accurate representation of pelvic mechanics in computational modeling of the human pelvis necessitates use of biofidelic finite element (FE) models. This dissertation developed and validated several FE models of the pelvis with validated pubic symphysis and then implemented it to (i) study deformation characteristics of the pubic symphysis, pelvic bone stresses, and injury mechanisms under side impact loads and (ii) investigate how the presence of periacetabular defects and subsequent cement filling affect the pelvic bone response in stance loading. In conjunction with these research goals, the first paper of this dissertation presents a novel and advanced male and female symphysis model, in which the interpubic disc and four pubic ligaments were represented by a three-parameter Mooney-Rivlin model and a transversely isotropic hyperelastic model, respectively, with extension to quasi-linear viscoelasticity. The unknown material constants were heuristically determined using inverse FE method, whereas the Prony series constants were calculated by curve-fitting to the experimental creep data. Close correlation between FE predictions and experimental data suggested validity of the symphysis model. The second paper presents evaluations of biomechanical responses of the pubic symphysis and pelvic injury mechanisms under drop tower side impact loads. The pubic symphysis underwent a combination of lateral compression, posterior bending, and shearing. Ligament strains exceeded the reported failure level, and the interpubic disc deformed over normal symphseal mobility, suggesting potential sources of joint damage during lateral impact to the pelvis. Since periacetabular bone metastases are known to cause severe pain and functional disability in cancer patients, neither the biomechanical consequences of the metastatic lesions nor the effectiveness of percutaneous acetabuloplasty was well understood. The third paper includes parametrical quantification of the relative effects of variations in defect size, cortex involvement, and cement modulus on strains and stresses of pelvic bones in single-legged stance loading. The results demonstrated that a defect with cortex penetration could substantially reduce pelvic bone strength and, thereby, the weight-bearing capacity of the acetabular roof and that cement filling had a restorative effect, depending on modulus. The present studies are clinically relevant and, ultimately, may help establish guidelines to select patient candidates for percutaneous acetabuloplasty treatment. |
