[Posterior C1-C2 transarticular screw fixation for atlantoaxial instability assisted by intraoperative 3-dimensional fluoroscopy-based navigation].

Objective: To assess the feasibility, efficacy and indication of posterior C1-C2 transarticular screw fixation for atlantoaxial instability assisted by intraoperative 3-dimensional fluoroscopy-based navigation.
Methods: From November 2005 to October 2012, 58 patients with atlantoaxial instability underwent posterior C1-C2 transarticular screw fixation assisted by intraoperative 3-dimensional fluoroscopy-based navigation. Those with excellent atlantoaxial reduction and no need for decompression underwent percutaneously minimally invasive procedures. Operative duration, blood loss volume, reduction of atlantoaxial joints and postoperative neurovascular complications were recorded. Screw positions were studied by postoperative computed tomography (CT) and divided into 3 categories. The follow-up period was at least 3 months. Local symptoms (assessed by visual analogue scale (VAS) score), neurological conditions (Nurick classification) and bone graft fusion were evaluated.
Results: Among them, the procedure was either open surgery (n = 51) or percutaneously minimally invasive surgery (n = 7). A total of 111 screws were placed satisfactorily. Five patients underwent only unilateral C1-C2 transarticular screw fixation. No severe complications were encountered. The mean operative duration was 202.2 ± 54.2 minutes and the average volume of blood loss 412.6 ± 281.2 ml. And the values were comparable to those for the traditional fluoroscopy-guided free-hand procedures. No statistical significance existed between open and percutaneously minimally invasive procedures in operative duration, blood loss volume and precision of screw placement. The patients with incompletely reduced C1-C2 dislocation had comparable clinical outcomes with those with complete reduction. After a 3-month follow-up, all of them showed significant improvements of local symptoms. VAS score decreased from 4.5 ± 1.3 preoperatively to 0.7 ± 0.8 postoperatively while the Nurick classification improved from 2.4 ± 1.1 to 0.6 ± 1.0. And bone graft fusion was satisfactory.
Conclusions: Posterior C1-C2 transarticular screw fixation for atlantoaxial instability assisted by intraoperative 3-dimensional fluoroscopy-based navigation is both feasible and safe. Combined with minimally invasive techniques, this procedure may achieve greater precision and minimal invasion.