109 Pullout Propertiy of Screw for Spinal Fixation

Abstract

Internal spinal fixation devices are commonly used for stabilizing spines with degenerative, traumatic, or tumorous disorder. However screw pullout is a possibility, especially if low density osteoporotic bone is encounterd. The final goal of this study is to propose optimum configuration of a screw for spinal fixation. Pullout tests were carried out using three types of polyurethane foam with different values of density and compressive strength. Pullout strength was changed depending on density and compressive strength of polyurethane foam. The effect of pre-bending moment on pullout strength was also discussed.