Posterior C1-2 Transarticular Screw Fixation in Atlantoaxial Instability

ABSTRACT

The atlantoaxial joint is a complex structure which facilitates rotation of the head on the neck. The transverse atlantal ligament is essential to retain the odontoid process of C2 in the anterior part of the C1 ring. Disruption or laxity of the transverse ligament, some odontoid process fracture result in atlantoaxial instability. In case of instability, stabilization is desirable to relieve pain and reduce the risk of neural damage. The isolated atlantoaxial instability with normal occipitoatlantal joint is generally treated by a monosegmental fusion. The standard fixation for C1-2 instability is posterior wiring using the Gallie, Brooks technique or their modifications. The most recent and innovative development in the evolution of upper cervical spine fixation is the use of C1-2 transarticular screw fixation. The transarticular screw fixation technique can be employed in situation where the posterior arch of C1 is absent or fractured and standard wiring technique risk posterior subluxation of C1, on C2, or for congenital odontoid anomalies and multiple failures of standard wiring techniques. The transarticular screw fixation of the atlantoaxial joints, with posterior bone grafting, provides good fixation and is biomechanically superior to wring methods. This paper presents the comparison of posterior fixation methods and the detailed introduction of posterior C1-2 transarticular screw fixation technique.