The Reconstruction Of A (C1-C3) Cervical Model And Finite Element Analysis Of Hangman's Fracture

Objectives:â‘ Todevelop finite element model of upper cervical spine (Compared with C0-C3),including disc, facet and major ligaments. For validation of the model, its ROM values were compared with ROM values determined in an in vitro study.â‘¡Force loads inducing Hangman's fracture were applied to the model to analyzing the stress distribution.Methods: We obtained the CT data from a healthy adult man for the regularly health examination. He was checked by radioactive and clinical examination and was proved that he has not any spinal disease. Then his cervical spine was scanned by Siemens Somatom Sensation 64 with 0.6mm thickness without any interval. We get the CT images and save the data with DICOM format. Then the CT images were inputted to the Materialise Mimics and product a 3D surface image of C0-C3 by selecting image, preconditioning and remeshing tools. The 3D image wad inputted to the ANSYS ICEM CFD8.0 with LIS format and became a 3D entity, And the element type and material properties were defined at the same time. The disc, facets and main upper cervical spine ligaments were modeled according to literature. The ROMs(CO-C1, Cl-C2, C2-C3) of the model under physical load were validated by compared with cadaveric data(12 cases) and the model was adjusted according to the cadaveric data so as to make the ROMs of the model fell within 1 SD of the experimental mean values. Force loads including flexion, extension, compression and tension were applied on the occiput to elucidate which load scenarios could result in Hangman's Fracture.Results:1. A three-dimensional finite element model of CO-C1-C2-C3 complex was established and validated. 2.â‘ Under tension load, higher stress was occurred in foreside of ring, atlanto-axial articulation, C2-3 disc, C2-3 facet joint and C3 spinosus.â‘¡Under compression load, higher stress was occurred in foreside of ring, atlanto-axial articulation, C2-3 disc. The posterior parts had lower stress.â‘¢Under extension load, higher stress was occurred in lateral mass and posterior arch of the ring, facet articulation and pars interarticularis of the axis.â‘£Under flexion load, higher stress was occurred in the anterior parts of the model, atlanto-occipital articulation, posterior arch of the ring, inferior facet articulation and pars interarticularis of the axis.Conclusions:1.A three-dimensional finite element model was developed. The model had higher precision. The model were validated by compared with cadaveric data and the model was adjusted according to the cadaveric data. 2.Forces of excessive flexion and extension were the main casual mechanisms leading to Hangman's Fracture. Whereas forces of compression and tension weren't the main casual mechanisms but they were the accessorial causes.