gms | German Medical Science

Objective: The best and safest technique for C1-C2 fusion for atlantoaxial instability is a matter of debate. Transarticular screw insertion as well as C1-C2 stabilization in a modified Goel-Harms technique using C1-lateral mass screws and C2-isthmic screws are feasible surgical options which bare specific challenges. To improve the safety of these procedures, neuronavigation is used with increasing frequency. However, even though results with regard to accuracy are promising, OR-times are significantly longer when using navigation. We present our series of 130 patients using freehand, fluoroscopy-guided C1-lateral mass and C2-isthmic screw insertion.

Methods: Clinical database of the neurosurgical department was screened for patients treated for traumatic atlantoaxial instability with posterior C1-C2 fixation. Positioning of the screws was rated using the Gertzbein & Robbins classification. Vertebral artery injuries, further treatment of this complication and/or revision surgeries for malpositioned screws were assessed.

Results: In 130 patients (median age 79 years ± 17,4; range: 7 to 99years) a total of 589 screws were inserted. Median OR-time was 112min +/- 45min; range: 37 to 254min). Fracture type 2 according to Anderson & D’Alonso occurred in 93, type 3 in 9 and atypical C2 fractures in 8 cases, combined fractures of C1 and C2 in 19 cases and a C1 fracture in one case. Good screw position according to Gertzbein & Robbins grades A (0mm extraosseous position) and B (≤2mm extraosseous) was achieved in 486 (83%) and 70 (12%) screws, respectively. Grade C (≤4mm extraosseous) and D (≤6mm extraosseous) occured in 18 (3%) and 14 (2%) screws, respectively. A complete malposition (Grade E, >6mm extraosseous) was seen in one screw (0,2%). Vertrebral artery canal breaching occurred in 30 screws (5%) with a complete obliteration in only 4 screws (0,07%, three in C1 and one in C2). Endovascular treatment (Coiling) was necessary in one case. None of the patients suffered clinically apparent vascular complications. Revision surgeries due to malpositioned screws were performed in nine patients (6 in C1 and 3 in C2, Revision rate 7%).

Conclusion: Freehand, fluoroscopy-guided posterior fusion of atlantoaxial fractures by C1-lateral mass and C2-isthmic screws is a safe and feasible technique also without the use of neuronavigation. The risk of vertebral artery injury is low but not to be underestimated.