Atlantoaxial Joint

articulatio atlantoaxialis

The atlantoaxial joint complex allows approximately 50 percent of total cervical spine rotation through the pivot joint between the odontoid process and the anterior arch of the atlas, held in place by the transverse ligament of the atlas. It is the most mobile joint in the cervical spine and the most vulnerable to instability from traumatic ligament rupture or rheumatoid arthritis destruction.

Region: Neck

Clinical Relevance

Clinical Notes

Atlantoaxial instability from rheumatoid arthritis is a surgical emergency when the posterior atlantodens interval is reduced to less than 14 mm, as the odontoid can compress the cervical spinal cord. The Ranawat criteria for neurological compromise guide the timing of surgical stabilisation. Down syndrome produces atlantoaxial instability from ligamentous laxity, requiring screening before contact sports participation.

Pathology

Common Injuries & Conditions

Atlantoaxial Instability

Excessive C1 on C2 translation from transverse ligament disruption or rheumatoid destruction, producing myelopathy risk that requires surgical C1-C2 fusion when progressive or symptomatic.

Odontoid Fracture

Fracture through the odontoid process from high-energy cervical trauma, classified by Anderson-D'Alonzo type, with type II at the odontoid base having the highest non-union risk requiring surgical fixation.