Atlantoaxial instability (AAI) is defined as excessive movement at the junction between the spine's first two vertebrae. It is unclear how common it is.

Tuberculosis with Atlantoaxial and Craniovertebral Pott's Disease Authors : Ulrich Weber , M.D. , and Hans Scherübl , M.D. Author Info & Affiliations Published December 5, 2002 ...

ORLANDO, Fla. — Type II odontoid fractures had a high rate of healing and a low risk of nonunion after treatment with posterior atlantoaxial screw-rod fixation, according to results of a study ...

A 13-year-old Pakistani girl underwent a life-saving surgery who had spent years with a neck stuck at a 90-degree angle. She was suffering from a disease called Atlanto-Axial Rotatory Dislocation.