ABSTRACT
Posterior transarticular screw fixation is effective treatment method in cases of atlanto-axial instabilities. Various surgical procedures have been described for stabilization of unstable C1-C2 complex. The conventional management methods, either a Gallie or Brooks fusion technique, have limitations such as post-operative rigid bracing and relatively high rate of non-union. Since Magerl developed a technique for posterior transarticular screw placement at C1-C2 in 1979, Noel I. Perrin published modified technique for atlanto-axial instability using percutaneous drill guide system in 1995. This instrumentation system improved limitations of conventional fixation technique and reduced complications as well as shortening of operation times. Between May 1997 and February 1998, modification of this surgical approach with Perrin screw system was used in the treatment of 12 cases of atlantoaxial instability. Transarticular screw was placed in conjunction with bone graft wiring through the percutaneous working drill guide. The causes of the instabilities were rheumatoid arthritis(5 cases), traumatic injuries(4 cases), post operative instability(1 case), and non-union with immobilization(2 cases) and other cause. Patient age was ranged from 18 years to 70 years. Mean operation time was 145 min(110 to 225) with mean blood loss was 180 ml. Intraoperative complication was drill tip fracture in 1 case and screw pullout in 1 case postoperatively. Neurological or vascular injury were not observed there was neither radiologic instabilities nor spinal deformities. Neurologic and symptomatic status were improved in all operated cases.