A Computed Tomographic Study of Vietnamese C1-C2 Morphology for Atlantoaxial Crew Fixation Techniques

Objectives: This study aimed to define variations in radiological C1 and C2 measurements among Vietnamese subjects and to determine the feasibility of implementing C1-2 fixation techniques. Material and Methods: From October 2017 to April 2018, 120 patients underwent thin slide computed tomography (CT) scans of the cervical spine, in our hospital. Various dimensions of the C1 and C2 were analyzed, using axial and sagittal reconstructions of CT images. Differences in characteristics between the two sides and between sexes were investigated, using Student’s t-test, with significance at P < 0.05. Results: The mean anteroposterior dimension and the transverse width of the C1 lateral mass were 19.7 ± 2.1 mm and 12.2 ± 1.7 mm, respectively. The mean angles of the screw, directed to the maximal medial, lateral, cranial, and caudal directions, were 36.6 ± 2.8°, 28.2 ± 3.0°, 49.6 ± 4.1°, and 26.4 ± 5.5°, respectively. The average isthmus height, internal height, and pedicle width of the C2 were 5.8 ± 1.0 mm, 4.8 ± 1.3 mm, and 5.0 ± 1.3 mm, respectively. No significant differences were observed for any parameters, between the left and right side of the C1 or C2 or between the two sexes. Conclusion: This study revealed that the morphology of the C1 and C2 did not differ between genders in the studied subjects, but morphologic variations exist between Vietnamese subjects and other populations. Pre-operative anatomy evaluations based on CT data are essential be performed for screw placement and trajectory planning to avoid neurovascular complications and to enhance the treatment outcome.