ABSTRACT
Objective Construct the finite element model of vertebral pedicle screw fixation in thoracolumbar fractures can obtain the intuitive systematic mechanical effects under different motion conditions, it has a very important significance to the patients' rehabilitation, evaluation of system stability and prognosis.In this study, the biomechanical effects of different motion states of thoracic and lumbar spine fracture models were analyzed by the finite element analysis method.Methods We selected 1 orthopedic health volunteers from Nanjing General Hospital of Nanjing Military Region in June 2014, established the finite element model by the CT scan data of the healthy volunteer, used the geometric cutting method for fracture simulation and replacement, assembled posterior orthopedic internal fixation system of vertebral pedicle screw, simulated the different motion states and obtained the stress nephogram and displacement graph of the nail-stick system..Results For the six-nail and two-rod internal fixation system of posterior nail-stick system which set nails through injured vertebrae, we used the finite element operation method to simulate the biomechanical characteristics of different modes of motion in space, it combined by the movement of six directions(flexion, dorsiflexion, left side bend, right side bend, left twist, right twist).The maximum stress(94.99±1.72MPa) and the maximum displacement(0.1854±0.0052mm) and the of the dorsiflexion were significantly lower than that of flexion[(126.82±5.56)MPa、(0.2502±0.0050)mm]、left side bend[(152.18±9.13)Mpa、(0.3172±0.0048)mm]、right side bend[(159.58±13.54)Mpa、(0.3315±0.0051)mm](P<0.05).Conclusion The method of finite element analysis can obtain clear and intuitive biomechanical data, which provides effective evidence for the evaluation of surgical efficacy, the development of postoperative rehabilitation methods and the evaluation of the stability of thoracolumbar spinal system.