Atlantoaxial dislocation

Joseph R Siebert PhD (Dr. Siebert of the University of Washington has no relevant financial relationships to disclose.)
Harvey B Sarnat MD FRCPC MS, editor. (Dr. Sarnat of the University of Calgary has no relevant financial relationships to disclose.)
Originally released January 20, 2008; last updated August 29, 2017; expires August 29, 2020

This article includes discussion of atlantoaxial dislocation, atlantoaxial instability, atlantoaxial rotatory subluxation, atlantoaxial subluxation, and C1-C2 instability. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Atlantoaxial dislocation is the loss of normal alignment and stability of the first (atlas) and second (axis) cervical vertebrae with respect to each other. Etiologies are various, including trauma, congenital factors, infection, and connective tissue and autoimmune disorders. The condition must be appropriately diagnosed and managed to prevent deformity, spinal instability, and potential neurologic injury. The author reviews the pertinent features of this disorder as it is relevant to a wide range of healthcare professionals.

Key points

 

• Dislocation of the first (atlas) and second (axis) cervical vertebrae (ie, atlantoaxial dislocation or subluxation) is a rare but serious condition.

 

• Etiology is often multifactorial, but contributing factors include trauma, congenital abnormality of bone or supporting ligaments, or inflammation.

 

• Physical deformation and spinal instability are possible results.

 

• Injury to the cervical spinal cord and death are the most serious consequences of dislocation.

Historical note and terminology

Please note the terms “odontoid process” and “dens” are synonymous and used interchangeably in this article.

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