Clinical and Biomechanical Analysis of Transarticular Screw Fixation for Atlantoaxial Instability

ABSTRACT

Transarticular screw fixation augmented with interspinous wiring technique for atlantoaxial instability was analyzed to provide immediate multidirectional rigid fixation and increase likelihood of fusion of C1-2 for atlantoaxial instability in several biomechanical studies. Transarticular screw fixation eliminates anterior, posterior translation at C1-2 and reduce flexion and extension movement. 13 patients with atlantoaxial instability were operated with posterior atlantoaxial facet screws fixation augmented with an interspinous C1-2 strut graft and posterior wire fixation technique. One patient died postoperatively from cardiac problem. All surviving patients restored C1-2 alignment and stability without complication due to instrumentation and osseous unions have developed even 2 cases of screw breakage developed. This technique was analyzed to be superior to wiring or clamp fixation biomechanically and leads to success without external orthosis in several series. But precaution is needed to avoid the vertebral artery injury.