Anteroposterior atlantoaxial subluxation in cervical spine osteoarthritis: case reports and review of the literature.

Nontraumatic anteroposterior atlantoaxial subluxation (AAS) has been described in several rheumatic or inherited disorders, especially rheumatoid arthritis and to a lesser extent the inflammatory spondyloarthropathies. We describe AAS secondary to osteoarthritis (OA) of the cervical spine in a 76-year-old man and a 73-year-old woman with severe cervical OA, symptomatic C1-C2 facet joints, and signs of generalized OA. Only 6 similar cases exist in the literature. OA should be added to the causes of AAS, and conversely AAS should be assessed in cases with severe OA of the upper cervical spine.