ATLAS Type IIIa

Burst fractures are axial load injuries resulting in both anterior and posterior ring fractures. The fractures can be uni- or bilateral.

Nondisplaced burst fractures are normally treated nonoperatively with close observation.

For the ATLAS fractures the Gehweiler classification is used together with the Dickman classification. 

Displaced fractures will present with a widening greater than 6.9 mm (rule of Spence: overhang on open mouth odontoid view) and suggests a Gehweiler type 3b injury.