Abstract
Low back pain and spinal disorders represent a major clinical apprehension as the population ages. With more than 1.4 million annual spine procedures, operative management is exerting a significant healthcare burden in the United States. Despite the new technologies and the advent of minimally invasive surgeries (MIS), the optimal surgical treatment for many spine pathologies is still controversial. Hence, revision surgeries, due to failure in attaining the surgical goals, have been very common. Comprehensive understanding of each patient condition is crucial in determining the best surgical treatment; however, the available tools used in diagnosis and specifying the treatment are still insufficient to provide such knowledge. Finite element modeling (FEM), an advanced computational method for structural stress analysis, was employed in orthopedic biomechanics applications since 1972 to evaluate the kinematics and kinetics of human tissues. With the advancement of the computational power and the ability to precisely reconstruct 3D models of the spine tissues, FEM is now a well-established tool for basic research in spine biomechanics. However, despite the exceptional capabilities of this method, it is yet not well exploited in patient diagnosis and in optimizing the surgical treatment. In this dissertation, a new theoretical approach that utilizes FEMs of the thoracolumbar spine to evaluate and compare different spine procedures is developed. In this approach, CT scans of a real human subject were reconstructed to build 3D anatomical models that are used in the FEM. Potential spine procedures were virtually performed on the FEMs and normal physiological loading conditions were applied on each surgical alternative. A novel steady state nonlinear biphasic analysis was employed to solve the model, which couples the fluid problem with a solid mechanics problem. Accordingly, the implications of each spine procedures on the biomechanics of the spine were evaluated and the optimal spine procedure, from a biomechanical perspective, was specified. Moreover, the possibility of the development of adjacent segment diseases due the surgical intervention was investigated. Spine procedures used in the treatment of lumbar spinal stenosis (LSS); a degenerative disease that accounts for 5% of patients who present with persistent low back pain, and thoracolumbar burst fractures (TBF); the most common site of spinal injury were particularly assessed. Several decompressive and spinal fusion surgeries through open or minimal invasive techniques, that utilized different sets of implantable devices, were examined. The results provided insights on the consequences of applying each surgical alternative and would definitely help practitioners to optimize the operative management for each patient.