Release, reduction, and fixation of one-stage posterior approach for basilar invagination with irreducible atlantoaxial dislocation

Purpose We evaluate the efficacy, safety and indications of single stage posterior release, reduction, and fixation of basilar invagination (BI) with irreducible atlantoaxial dislocation (IAAD). Materials and methods Seventeen patients with BI and IAAD consecutively underwent one-stage release, reduction, and fixation by a posterior approach from July 2000 to June 2015 were followed up for at least 12 months. There were 8 males. Mean age was 56 35.2 +/- 13.8 years (range 12-56). The clinical symptoms and signs of the patients were recorded. Pre- and postoperative imaging examinations were performed. Neurological function was assessed using the Japanese Orthopedic Association (JOA) and Ranawat scores. Results Average follow-up time was 47.4 months (12-97 months). The JOA score increased from preoperative 4-10 (8.06 +/- 2.52) to postoperative 13-16 (15.20 +/- 0.62). The preoperative Chamberlain line, McRae line, Wackenheim line, atlantodens interval, and cervico medullary angle were 12.52 +/- 5.17 mm, 6.59 +/- 3.04 mm, 6.96 +/- 4.32 mm, 9.88 +/- 1.93 mm, and 115.35 +/- 12.40 degrees, respectively. The postoperative values were 2.0 +/- 3.67 mm, -3.06 +/- 1.85 mm, -1.76 +/- 2.88 mm, 1.17 +/- 1.18 mm, and 136.76 +/- 11.44 degrees, respectively. Conclusion One-stage release, reduction, and fixation for patients with BI and IAAD through a posterior approach is safe and efficient.