Congenital Hypoplasia of the Posterior Arch of the Atlas Associated with a Fracture of the Odontoid Process: A Case Report

ABSTRACT

STUDY DESIGN: Case report. OBJECTIVES: To report a rare posterior arch hypoplasia of the atlas and review the clinical significance. SUMMARY OF LITERATURE REVIEW Congenital hypoplasia of posterior arch of the atlas is uncommon. In particular, the combined fracture of the odontoid process has not been reported. MATERIALS AND METHODS: A 56-year-old man developed severe neck pain after a traffic accident. Cervical CT scan revealed a fracture of the odontoid process and hypoplasia of posterior arch of the atlas. RESULTS: Bony union was achieved after halo vest immobilization for three months. CONCLUSIONS: Hypoplasia of posterior arch of the atlas is determined incidentally in asymptomatic patients. However, the patients should be evaluated in detail with a 3D CT and MRI to avoid a misinterpretation as fracture, instability or misdiagnosis.