• Scott Simon, Martin Davis, Dewey Odhner, Jayaram Udupa, and Beth Winkelstein.
• Department of Neurosurgery, University of Pennsylvania, Philadelphia, USA.
• Spine. 2006 Jan 1; 31 (1): 44-50.

Study DesignComputerized tomographic study of human cadavers undergoing traction and flexion-extension bending.ObjectivesTo investigate the feasibility of using computerized tomography techniques to quantify relative vertebral motions of the cervical spine and cervicothoracic junction (CTJ), and to define normative CTJ kinematics.Summary Of Background DataDespite developing an understanding of the mechanical behavior of the cervical spine, little remains known about the cervicothoracic junction. The CTJ is more difficult to image than other cervical regions given the anatomic features of the surrounding bones obstructing CTJ visualization. As such, limited data have been reported describing the responses of the CTJ for motions and loading in the sagittal plane, confounding the clinical assessment of its injuries and surgical treatments used at this region.MethodsHelical CT images of the cervical spine and CTJ were acquired incrementally during each of flexion, extension, and cervical traction. Vertebral surfaces were reconstructed using the specialized image analysis software, 3DVIEWNIX. A mathematical description of relative vertebral motions was derived by computing rigid transformations. Euler angles and translations were calculated. Regional spine stiffness was defined for traction.ResultsThe CTJ was found to be much stiffer (779 N/mm) than the cervical spine (317 N/mm) in tension. In flexion-extension bending, the CTJ was similar to the lower cervical spine. The CTJ demonstrated significantly less coupled motion than the cervical spine.ConclusionsThe CTJ, as a transition region between the cervical and thoracic spines, has unique kinematic characteristics. This application of kinematic CT methods is useful for quantifying unreported normative ranges of motion for the CTJ, difficult by other conventional radiologic means.

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