Objective: The atlantoaxial instability often requires posterior fixation surgery. Multiple techniques have been described for C1-C2 fixation. Transarticular atlantoaxial screw has been demonstrated to be effective for C1-C2 stabilization. However, up to 20% of patients are not candidates for the procedure. New technique concerning the placement of individual screws in C1 lateral mass and C2 pars screw with additional rods for their connection was described, either as a salvage method for unsuccessful C1-C2 stabilization or as an effective alternative technique. The authors presented their experience using C1 lateral mass and C2 pars screws with rod fixation for C1-C2 stabilization.

Material and Method: Between May 2007 and October 2008, 10 patients (7 male, 3 female) whose age ranged from 15 to 59 years-old underwent posterior fixation using C1 lateral mass and C2 pars screw with rod fixation. Six patients had atlantoaxial subluxation due to os odontoideum, two patients had chronic C1-C2 subluxation, and two patients had acute C1-C2 subluxation from a motor vehicle accident. All screws were placed under lateral fluoroscopic guidance.

Results: C1 lateral mass and C2 pars screw with rod fixation were used to achieve C1-C2 stabilization in all patients. All screws were positioned correctly in both C1 and C2. There were no permanent complications. In all cases, rigid fixation was confirmed on postoperative radiographs and maintained on follow-up radiographs.

Conclusion: The lateral mass and C2 pars screw with rod fixation is an effective method of stabilizing the atlantoaxial complex. This procedure provides rigid fixation with relative safety.

Keywords: C1 lateral mass screw, C2 pars screw, Posterior fixation, Craniocervical junction, Atlanto-axial fixation, Polyaxial screws and rods