Caudally Directed Inferior Facetal and Transfacetal Screws for C1-C2 and C1-2-3 Fixation.

An alternative caudally directed C2 inferior facetal screw is described. Such screw insertion can form the axial stabilization point in cases undergoing atlantoaxial lateral mass plate/rod and screw fixation and those undergoing C1-2 and C1-2-3 spinal fixation. The C2 screw courses from the medial point of the pedicle-laminar junction and travels caudally and laterally toward the C2-3 articulation. Deploying a longer screw that traverses in a transarticular fashion into the facetal mass of C3 vertebra, one can perform C1-2-3 stabilization. Sixteen patients underwent C2 inferior facetal or C2-3 transarticular screw in combination with a C1 screw for atlantoaxial fixation. Three of these patients with multilevel spinal instability underwent atlantoaxial and C2-3 fixation using the discussed technique. The technical issues, anatomic subtleties, and indication for use of the C2 inferior facetal screws are discussed. With an average follow-up of 9 months, all screws have successfully provided stability that resulted in arthrodesis of the treated spinal segments. A caudally directed C2 inferior facetal screw can enhance the armamentarium of the surgeon, provide an alternative to conventional techniques or a bailout option, and add to the safety of the procedure of atlantoaxial lateral mass fixation in anatomically challenged situations.