Unilateral pedicle screw fixation of lumber spine: A safe internal fixation method

BACKGROUND: Unilateral pedicle screw fixation several advantages, including reduced trauma and low cost. However, its stability and safety have not been widely recognized. In this study, the biomechanical differences in the vertebral body and screw-rod system after unilateral and bilateral pedicle screw fixation were compared using both the finite element model and calf lumbar model. METHOD: We used the verified finite element model to establish unilateral and bilateral posterior lumbar surgery models. The biomechanical data of different parts of the models were recorded under different working states. Then, three calf lumbar models were selected to simulate different working states with the help of a universal testing machine and other instruments. Finally, the biomechanical data of the screw-rod system were obtained from a static strain test and analysis system. RESULTS: By analyzing and comparing biomechanical data obtained using two different methods, this study found that unilateral pedicle screw fixation does not bring excessive loads to the lumbar spine and screw-rod system. CONCLUSION: From the perspective of biomechanics, unilateral pedicle screw fixation is considered a safe and reliable implantation technique.