Anterior Extrapharyngeal Fixation of the Atlanto–Axial Joints

Abstract

Introduction The atlanto–axial joints can be easily exposed from a unilateral submandibular extrapharyngeal approach. Decortication and intrajoint bone grafting can be easily accomplished. Rigid anterior fixation of the joint is possible without any risk to the vertebral arteries. Materials and Methods Between April 2008 and September 2014, 95 patients, 50 male and 45 female patients, in the age group of 12 to 82 years, were offered this procedure. 55 patients had anterior transarticular screws, 40 patients had anterior screw plate fixation (AAD 63 patients, tuberculosis 20, fixed AAD with Basilar invagination 12). All patients underwent preoperative dynamic X-rays of craniovertebral junction, computerized tomography (CT scan) of C1–C2 static and dynamic study with bone window settings and 3D reconstruction, magnetic resonance imaging (MRI), and MR angiography to study the course of vertebral artery. Stevenson technique (22 patients) for exposure to reach the prevertebral space at C1–C2. Technique 1: plate and screws (C1 lateral mass and C2 body); Technique 2: anterior transarticular screws across C1–C2 joint. Results Average procedure time was 3 hours, no case required blood transfusion, reoperation occurred in seven cases; three screw malposition both ipsilateral (right sided), reoperated within 48 hours and screw repositioned correctly. One overdistraction of C1–C2 joint due to screw not piercing the C1 lateral mass and pushing the lateral mass of C1 away from C2 (because of inadequate drilling of C1 lateral mass). Reoperated on the 3rd day and lateral mass of C1 drilled correctly and the screw passed successfully. Two inadequate excisions of odontoid process had to be removed transorally after 3 weeks because of excessive backward angulation of odontoid process. One case of screw loosening that was due to incorrect plate contouring, reoperation after 3 weeks when patient had come for first postoperative follow-up. Follow-up in 75% for 24 months. Rigid fixation in 100%, mortality 0%. Conclusion Anterior extrapharyngeal approach allows for reduction of the atlanto–axial dislocation, opportunity for bone grafting of the joint, and with anterior C1 lateral mass and C2 body screw plate fixation or anterior transarticular screws, provides rigid fixation without any risk to the vertebral artery, venous plexus, or spinal cord.