Odontoid Fracture Nonunion with Atlantoaxial Instability, Myelopathy, High-Riding Vertebral Artery, and Narrow Pars Treated with C1-C2-C3 Posterior-Only Fixation: First Case Report

Abstract

Nonunion is a known complication of odontoid fractures. However, coexisting instability and neurological involvement render odontoid fixation alone insufficient for effective management. This scenario necessitates atlantoaxial fusion, which can be achieved through anterior, posterior, or combined approaches. We report a case of a 51-year-old female with posttraumatic nonunion of type II odontoid fracture, atlantoaxial instability, high-riding vertebral artery, and narrow pars, presenting with spastic quadriparesis. She underwent C1–C3 posterior cervical fixation and fusion. The patient demonstrated significant neurological improvement at 1-year follow-up. This case highlights the importance of ruling out cervical myelopathy in such patients. There are no prior reports in the literature describing odontoid nonunion leading to atlantoaxial instability and cervical myelopathy in the presence of a high-riding vertebral artery. The case also underscores the ongoing dilemma regarding the ideal surgical approach in such complex anatomical scenarios at the C1–C2 junction, known for its numerous variations.

Keywords

nonunion odontoid - myelopathy - C2 pars screws fixation - high-riding vertebral artery - atlantoaxial instability

Authors' Contributions

C.S.S. prepared the manuscript, analyzed the findings, and assisted in the case. M.S.T. performed the surgery and contributed to manuscript preparation. M.B. also assisted in the preparation of the manuscript.

Ethical Approval

Ethics approval and consent were obtained from the Institutional Ethics Committee IEC/SNMC.

Publikationsverlauf

Artikel online veröffentlicht:
22. Dezember 2025

• References

• 1 Greene KA, Dickman CA, Marciano FF, Drabier JB, Hadley MN, Sonntag VK. Acute axis fractures. Analysis of management and outcome in 340 consecutive cases. Spine 1997; 22 (16) 1843-1852
• 2 Anderson LD, D'Alonzo RT. Fractures of the odontoid process of the axis. J Bone Joint Surg Am 1974; 56 (08) 1663-1674
• 3 Ricciardi L, Trungu S, Scerrati A. et al. Odontoid screw placement for Anderson type II odontoid fractures: how do duration from injury to surgery and clinical and radiological factors influence the union rate? A multicenter retrospective study. J Neurosurg Spine 2020; 34 (01) 27-31
• 4 Grauer JN, Shafi B, Hilibrand AS. et al. Proposal of a modified, treatment-oriented classification of odontoid fractures. Spine J 2005; 5 (02) 123-129
• 5 Mohamed A, Ehab Y, Hassanin A, Ibrahim A. Anterior odontoid lag screw fixation in type II odontoid fractures. Egypt Orthopaed J 2024;
• 6 Rathod T, Prabhu RM, Mohanty SS, Chandanwale A. A novel technique of managing an irreducible posteriorly displaced type 2 odontoid fracture: a case report. Surg Neurol Int 2023; 14: 371
• 7 Avila MJ, Farber SH, Rabah NM. et al. Nonoperative versus operative management of type II odontoid fracture in older adults: a systematic review and meta-analysis. J Neurosurg Spine 2023; 40 (01) 45-53
• 8 Shamji MF, Alotaibi N, Ghare A, Fehlings MG. Chronic hypertrophic nonunion of the Type II odontoid fracture causing cervical myelopathy: case report and review of literature. Surg Neurol Int 2016; 7 (Suppl. 03) S53-S56
• 9 Ho AW, Ho YF. Atlanto-axial deformity secondary to a neglected odontoid fracture: a report of six cases. J Orthop Surg (Hong Kong) 2010; 18 (02) 235-240
• 10 Shaaban ATE, Doomi A, Belkheir S. A case of cervical myelopathy following chronic hypertrophic non-union type 2 odontoid fracture managed with posterior C1 decompression and C1-3 instrumentation: case report and brief review of literature. Surg Neurol Int 2020; 11: 132