Preoperative oblique axial computed tomographic imaging for C1-C2 transarticular screw fixation: technical note.

C1-C2 transarticular screw fixation is an increasingly popular surgical method of treating atlantoaxial instability. When properly performed, it can safely provide fusion rates near 100%. However, the technique of screw insertion into this region allows only a small margin for error. Preoperative radiological assessment is essential to analyze the morphology of the region, assess for vertebral bony and vascular anomalies, and define the tolerances for the transarticular screws along their planned trajectory. As an adjunct to the preoperative planning of C1-C2 transarticular screw fixation, a unique, easily obtainable method of computed tomographic imaging, using thin-section oblique axial computed tomographic images of the C1-C2 region, is described.