Breakage Risk in Pedicle Screw Fixation with Flexible Rods in Lumbar Spine

INTRODUCTION Breakage of the screws which may cause non-union or collapse of vertebral structures has been a complication of the pedicle screw fixation at a rate of 3-7 % [1-2]. Recently, flexible rods have been used for dynamic stabilization to avoid complications such as adjacent segment degeneration due to excessive stiffness of the spinal fusion by allowing intersegmental motion at the surgical level [3]. Thus, it is necessary to investigate the influence of the flexible rods on the breakage risk in the pedicle screw fixation. However, there have been few studies of the breakage risk in the dynamic stabilization system using flexible rods. In this study, the breakage risk in the pedicle screw fixation was analyzed using finite element method for the rods with various flexibilities.