Atlantoaxial Instability

Excerpt

The atlantoaxial joint is the most mobile joint, with several critical neurovascular structures traversing through it.The atlantoaxial segment consists of the atlas (C1) and axis (C2) and forms a complex transitional structure bridging the occiput and cervical spine. The functional result of the joint is two-fold: (1) providing support for the occiput and (2) providing the greatest range of motion and flexibility possible while maintaining stability. The instability in this joint is usually congenital, but in adults, it may be due to an acute traumatic event or degenerative disease.