Surgery for non-inflammatory degenerative atlantodental instability: strategy and clinical outcome in 36 patients

Introduction: Patients suffering from C1-C2 instability with spinal cord compression may suffer from burdening neck pain and myelopathy, reducing their mobility and quality of life. Formerly known as a distinct entity in rheumatoid arthritis, C1-C2 instability may occur due to severe degenerative arthrosis without being caused by autoimmune or inflammatory factors in an era of fading inflammatory processes.

Methods: We retrospectively assessed all patients undergoing C1-2 stabilization for symptoms and radiographical signs of C1-2 instability with a retrodental pannus in our neurosurgical department from January 2012 to December 2021. We excluded all patients with inflammatory diseases. Radiological parameters, surgical data, and clinical follow-up data were retrieved from our records to investigate the clinical outcome.

Results: In total, we included 36 patients for further analysis. The mean age was 72 years. All patients underwent C1-2 fixation with a fusion of the C1-C2 joint, and 61% underwent a decompression via C1 laminectomy for clinical symptoms of myelopathy. The median mJOA score improved from 14/18 preoperatively to 15/18 after surgery and a score of 16/18 at a median follow-up of 3 months. The mean preoperative atlantodental distance was 2mm. 71% of the patients improved clinically after surgery, 29% remained stable, and 9.7 % deteriorated at follow-up. The overall complication rate was low at 8.6%, including two asymptomatic vertebral artery injuries and one CSF leakage.

Conclusion : C1-C2 fixation achieved satisfying results in patients suffering from non-inflammatory atlantoaxial instability. Patients suffering from neck pain and symptoms of myelopathy improved until follow-up with the posterior approach.