抄録
Lumbar spinal fusion with unilateral pedicle screw and rod system (unilateral PS) has received favorable clinical reports. However, there are very few reports about mechanical properties of this system. The purpose of this study was to investigate the mechanical properties of the lumbar spinal fusion with unilateral PS. Functional spinal units (FSUs) from wild boar cadavers were used. Bending tests in a total of eight directions were performed to clarify the range of motion (ROM) for each FSU using a 6-axis material testing machine. The results showed that while the fixation for bilateral PS model is high in all bending directions, the ROM for the unilateral PS model depends on the bending directions, and the fixation in the diagonal direction of pedicle screw insertion is low. Furthermore, it was considered that the factor of the low fixation in the diagonal direction is the relative rotation of the screw toward the vertebral body.
