Isocentric C-arm three-dimensional navigation versus conventional C-arm assisted C1-C2 transarticular screw fixation for atlantoaxial instability

The Isocentric C-arm 3D navigation has been widely used in superior cervical surgeries in recent years. Several clinical researches reported that navigation system was an effective support device for treatment of atlantoaxial instability. But there were few studies about the advantages of navigation system compared to conventional C-arm fluoroscopy in C1-C2 transarticular screw fixation for atlantoaxial instability. The aim of the study was to evaluate the precision of computer-assisted C1-C2 transarticular screw fixation (Magerl's technique) for atlantoaxial instability and compare the clinical results with conventional C-arm fluoroscopy. Forty-two patients diagnosed as atlantoaxial instability who underwent C1-C2 transarticular screw fixation under two different fluoroscopy methods were studied. The Iso-C 3D navigation group included 18 patients and the other 24 patients were in the conventional C-arm group. The clinical and radiographic results were recorded and compared between the two groups. Patients were followed up with clinical examination and radiographs at a mean of 18.4 months. There were no significant differences between two groups in the mean age, gender, and causes of atlantoaxial instability. The mean blood loss in the navigation group was 236.1 +/- A 28.5 mL versus 308.3 +/- A 21.2 mL in the conventional C-arm group. The radiation time was significantly reduced using 3D navigation (48.8 +/- A 1.05 s versus 60.3 +/- A 2.23 s). Overall, 97.2 % (35/36) of 3D navigated screws and 91.7 % (44/48) of fluoroscopy screws were placed into the C1-C2 transarticular passages. Thirty-nine of forty patients showed evidence of solid fusion after 12 months on cervical plain radiographies or CT scans. On comparing the two imaging techniques, it was found that using Iso-C 3D navigation can improve accuracy of the C1-C2 transarticular screws, decrease intra-operative fluoroscopic time and blood loss, and not prolong the operative time. This study demonstrates that Iso-C 3D navigation is a safe and effective means of guiding C1-C2 transarticular screw fixation for atlantoaxial instability.