C1-C2 posterior screw fixation in atlantoaxial fractures revisited: technical update based on 127 cases.

Posterior fusion of traumatic odontoid fractures by C1 lateral mass and C2 isthmic screws (modified Harms-Goel technique) is a viable alternative to transarticular screw fixation due to its universal applicability. This retrospective study reports on a series of 127 patients. Our clinical database was screened for patients with fractures of the upper cervical spine incorporating a C2 fracture, operated on between 2007 and 2015. Patients were included if fused by internal fixation via C1 lateral mass screws, C2 isthmic screws in freehand technique under lateral fluoroscopy. Screw placement was controlled postoperatively by computed tomography and rated using the Gertzbein & Robbins classification. Surgery-related complications, consecutive treatment, revision surgeries and duration of surgeries were registered. In total, 127 patients were identified with altogether 572 screws. Correct screw positions of grade A and B according to Gertzbein & Robbins were achieved in a total of 539 (94.2%) screws (grade A: 453 (79.2%); grade B: 86 (15%)), grade C screw malpositions noted in 21 (3.7%), grade D in 10 (1.7%) and grade E in 2 (0.3%) screws. Vertebral artery canal breaches occurred in 29 screws (5.1%), with vertebral artery occlusion in 4 patients. Coiling of injured vertebral artery had to be performed in one patient. None of these patients suffered clinically apparent cerebrovascular complications. Revision surgery was performed in 8 patients (6%). Posterior fixation of atlantoaxial fractures by C1 lateral mass and C2 isthmic screws with fluoroscopy without navigation is a safe and feasible method but not free of risk of vertebral artery injuries. These slides can be retrieved under Electronic Supplementary Material.