Transarticular Screw Fixation in Atlantoaxial Instability

ABSTRACT

Atlantoaxial joint is a complex and unique structure which promotes rotation of head. Disruption of the transverse ligament and odontoid process fracture caused by trauma result in atlantoaxial instability. The instability must be corrected to relieve pain and to reduce the risk of neural damage and possibility of sudden death. The most recent and technologically advanced fixation method of C1-2 instability is the use of C1-2 transarticular screw fixation. The transarticular screw fixation augmented with interspinous wiring technique provide immediate multidirectional rigid fixation and increase the fusion rate of atlantoaxial instability. It can be employed in situations where the posterior arch of C1 is absent or fractured and in situations where standard wiring techniques pose risky posterior subluxation of C1 on C2, or for congenital odontoid anomalies. Twenty-one patients with atlantoaxial instability were operated with posterior transarticular screw fixations augmented with interspinous C1-2 strut graft and posterior wire fixation technique. All patients restored C1-2 stability without complication. This technique seems to be superior biomechanically when compared with other posterior fixation methods. Precaution is needed to avoid the vertebral artery injury.