Atlantoaxial instability secondary to rheumatoid arthritis.

Multiple elements contribute to the stability of the anterior C1-C2 articulation, making this region subject to pathologies including trauma, inflammation, infection, and congenital deformities. C1-C2 instability places a patient at risk for significant neurologic compromise. Radiologic imaging plays a fundamental role in diagnosing atlantoaxial instability, indicating etiology, showing details of associated abnormalities, and providing information for planning treatment.