MATERIAL and METHODS: Archive files of adult patients, who were operated for posterior C1-C2 stabilization with screw and rod in our clinic between January 2006 and January 2016, were analyzed. Twenty-eight patients, who had pre- and postoperative images, follow-up forms and who were followed for at least one year, were analyzed. Preoperative clinical and radiological records, preoperative observations, postoperative complications, and clinical responses were evaluated.

RESULTS: The mean age of the 28 patients (11 females and 17 males) was 44.7 years (range 21-73 years). Fixation was performed with a C1-C2 screw-rod system on the basis of the following diagnoses; type 2 odontoid fracture (n=16), basilar invagination (n=5), C1-C2 instability (n=5), and atlantoaxial subluxation secondary to rheumatoid arthritis (n=2). Lateral mass screws were inserted at the C1 segment. C2 screws were inserted on bilateral pedicle in 12 cases, bilateral pars in 4, bilateral laminar in 8 and one side pars, and one side laminar in 4 cases. There was no screw malposition. Neither implant failure nor recurrent instability was observed during the follow-up period. Significant clinical improvement was reported according to the assessments based on JOA and VAS scores.

CONCLUSION: C1-C2 screw fixation is regarded as a more successful and safe method than other fixation methods in surgical treatment of atlantoaxial instability considering the complications, success in reduction, fusion and fixation strength. The C2 laminar screw technique is as successful as the other alternatives in fixation and fusion. Keywords : Atlantoaxial instability, C1 lateral mass, C2 laminar, C2 pedicle, Screw