An anatomic consideration of C2 vertebrae artery groove variation for individual screw implantation in axis.

Study Design: Retrospective case series.

Objectives: To identify the variation of C2 vertebral artery groove (VAG) based on the thin-slice computed tomography (CT) scan and choose an individual screw placement method to decrease risk of malposition.

Background: C2 pedicle screws can be successful anchors for a variety of cervical disorders.