Pedicle-screw-rod fixation system is very popular surgical remedy for degenerative disc disease. It is important to observe load vs. spinal motion characteristic for better understanding of clinical problems and treatment of spinal instability associated with low-back pain.Ti6Al4V pedicle-screw-rod fixation system highly restricted the ROM of the spine, which is improved by using UHMWPE and PEEK, having lower stiffness. The foramen height did not vary significantly for any implant materials. In terms of ROM and maximum stress, PEEK rod may be considered for a better implant design to get better ROM and thus mobility.Many successful attempts to increase pullout strength of pedicle screws in osteoporotic bone have been accompanied with an increased risk of catastrophic damage to the patient. To avoid this, a single-armed expansive pedicle screw was designed to increase fixation strength while controlling postfailure damage away from the nerves surrounding the pedicle. The screw was then subsequently tested in two severely osteoporotic models: one representing trabecular bone (with and without the presence of polymethylmethacrylate) and the other representing a combination of trabecular and cortical bone. Maximum pullout strength, stiffness, energy to failure, energy to removal, and size of the resulting block damage were statistically compared among conditions. While expandable pedicle screws produced maximum pullout forces less than or comparable to standard screws, they required a higher amount of energy to be fully removed from both models. Furthermore, damage to the cortical layer in the composite test blocks was smaller in all measured directions for tests involving expandable pedicle screws than those involving standard pedicle screws. This indicates that while initial fixation may not differ in the presence of cortical bone, the expandable pedicle screw offers an increased level of postfailure stability and safety to patients awaiting revision surgery.