Biomechanical evaluation of anterior transarticular screws on C1-2，a three-dimensional finite element analysis

English Keywords:Upper cervical vertebrae  Internal fixation  Biomechanics  Ｆinite element method

English Abstract:

  【Abstract】　Objective：To evaluate the biomechanical features of anterior transarticular screws placement by finite element method.Method：A healthy male volunteer aged 21 years old underwent CT scan at C0-C3 （slice width=1mm）.Three-dimensional finite element model of upper cervical spine was established by MIMICS 13.0，Freeform Plus and ANSYS 9.0. C1-2 instability was simulated by removing transverse ligament，and transarticular screws were placed based on standard surgical protocol.Specimen was subjected to flexion-extension，lateral bending and axial rotation load.The ROM of screws and load transfer under different direction were evaluated biomechanically.Result：Although the ROM after screw placement was small in all direction，the ROM in flexion-extension（0.72°，1.08°） was obviously bigger than that of lateral bending and axial rotation（0.39°，0.32°）.Stress was found concentrating around the transarticular area under all directions and had the maximum value of 10.58×107Pa under extension movement.Conclusion：Anterior　transarticular screws show excellent biomechanical effect，especially under lateral bending and axial rotation.The transarticular area which the screws pass through is apt to develop load bearing，which predispose the instrument at failure.