OBJECTIVETo establish the cervicothoracic spine finite element model with three-dimensional finite element method, verify the effectiveness of this model and explore the stress distribution.

METHODSDICOM image data of one normal healthy young male volunteer were obtained by spiral CT scan and processed with Mimics software. Datas were imported to ANSYS software to become a 3D entity. Disc structure and the main ligament were added. Disc structure was added using the shell-nuclear unit, representing the annulus fibrosus and nucleus pulposus. Ligament structure was established with 2-node cable element, the beginning and ending points of the ligament and the cross-sectional area were determined in accordance with references. C(6,7) and C7T1 facet joints were definded as the nonliner contact joints with friction coefficient. The lower surface of TI in all the directions was completely fixed in this model. In the model 2.0 Nm pure torque were imposed on C6, and the extension, flexion, axial rotation and lateral bending experiment were conducted. The experimental results were compared with the in vitro biomechanical tests.

RESULTSThe cervicothoracic spine finite element model included 169,317 nodes and 106,242 units, and consistent with the in vitro biomechanical tests. The three-dimensional finite element model was in good running under external force.

CONCLUSIONIt is a convenient and precise method for physicians to establish the finite element model of the cervicothoracic junction. This method facilitates the computer study on the biomechanical behavior of the local structures of the model under various pressure conditions.