Management of traumatic atlanto-axial instability: A retrospective study of eight cases

Background: C1 lateral mass-C2 transpedicular fixation is an accepted surgical procedure of choice in a large number of cases with traumatic atlanto-axial instability. However, bony and vascular anomalies can predispose to unacceptably high risk with this procedure, And hence are the contraindications for this procedure. The purpose of this study is to analyze the clinical and radiological results in such cases for which only unilateral fixation has been performed in cases where bilateral fixation could not be performed due to various reasons. Materials and Methods: Eight patients (7 males, 1 female) with a mean age of 41.12 years (range 12-68 years), who presented with traumatic atlanto-axial instability and in whom bilateral fixation could not be performed, were treated with unilateral C1 lateral mass-C2 transpedicular fixation. Of these cases, preoperative vertebral artery occlusion was noted in one case, iatrogenic vertebral artery injury in two cases and bony anomalies or fractures in the remaining of five cases. All patients were evaluated clinically with the American Spinal Injury Association (ASIA) scale and radiologically with computed tomography scans and serial X-ray using criteria to evaluate stability. Results: All cases were evaluated at 6 months followup with mean followup of 2 years and one month (range 6 months to 4 years). All eight patients showed adequate stability and fusion at 6 months; clinically there was no significant restriction of neck movement in any of the patient. There was no neurological deterioration in any of the patient at their last follow-up. Conclusion: Unilateral C1 lateral mass-C2 transpedicular fixation could be considered a viable option in cases of traumatic atlanto-axial instability where vascular and osseous anomalies contradict a bilateral fixation.