Finite Element Analysis (FEA) is an essential tool in biomedical engineering and particularly in spinal biomechanics research. Subject-specific spine models provide a more realistic representation of load transmission, especially when there are structural changes involved, such as disc degeneration, a pathology strongly associated with chronic low back pain and mechanical instability. Under such a circumstance, it is paramount to include in the model, besides bone anatomy, the mechanical characterization of the intervertebral discs that is afforded by MRI images. The aim of this thesis is the creation of a three-dimensional patient-specific thoraco-lumbar spine model, developed from computed tomography (CT) and magnetic resonance imaging (MRI).