Clinical outcome of posterior C1-C2 pedicle screw fixation and fusion for atlantoaxial instability: A retrospective study of 86 patients.

We retrospectively studied the clinical results of posterior C1-C2 pedicle screw fixation and fusion for 86 patients diagnosed with atlantoaxial instability from January 2002 to January 2013. The study population included 48 men and 38 women, with an average age of 42.6 (range, 16-69years old). The causes of atlantoaxial instability could be divided into traumatic fracture (44 patients), congenital malformation (17 patients), rheumatoid arthritis (15 patients), and other causes (nine patients). The mean follow-up duration was 33.9months (range, 13-72months). The average operative time was 133.0min (range, 90-290min), and the mean blood loss during the operation was 185.7ml (range, 110-750ml). No patient experienced neurological function worsening related to the surgical procedure. In addition, 63% of the patients who presented with neurological symptoms reported improvement after surgery. Screw placement and reduction was achieved satisfactorily in all the patients and their neck pain was greatly relieved. Plain radiography and CT scans indicated solid fusion after 12months in all the patients. We suggest that C1-C2 pedicle screw internal fixation is a reliable method for treating atlantoaxial instability.