微动椎弓根螺钉的生物力学仿真评测

利用有限元法评估一种微动椎弓根螺钉的生物力学性能.基于人体脊柱CT图像数据建立腰椎L3-L4节段有限元模型，并在此基础上建立坚强固定(M1)、微动固定(M2)、混合固定(M3)3种内固定有限元模型，对有限元模型施加模拟生理载荷，计算内固定节段各项生物力学参数.仿真结果表明，微动椎弓根螺钉在屈伸方向增大了内固定节段的椎间活动度，其中前屈工况增大95%，后伸工况增大83%;改善了载荷在椎间的传递，增大终板正常生理性刺激应力4.25%~5.7%;降低了植入体上的应力集中效应，在前屈、后伸和侧弯工况下降低椎弓根螺钉应力9.2%~16.2%.

Biomechanical Simulation of the Micro-dynamic Pedicle Screw

By using the finite element method， the biomechanical performance of the micro-dynamic pedicle screw was evaluated. A three-dimensional finite element model of lumbar segments L3-L4 was reconstructed based on CT images of human spine. And on this basis， three kinds of L3-L4 fixed models: rigid fixation(M1)， micro-dynamic fixation(M2) and hybrid fixation(M3) were built to calculate the biomechanical parameters of surgical segments under the simulative physiological load. The simulation results showed that the micro-dynamic pedicle screw increases the range of motion(ROM) of the fixation segments in the direction of flexion and extension(95% in flexion and 83% in extension). The dynamic performance of the screw improves load transmitting between the lumbar motor units， and increases the normal physiological stimulation stress of the endplates by 4.25%~5.7%. Besides， the micro-dynamic fixation reduces the stress concentration effect on the implants， and the reduction of the pedicle screw stress is 9.2%~16.2% under flexion， extension and lateral bending conditions.