C1 anterior arch (plough) fracture - type 1

Case contributed by Sarah AlJahdali
Diagnosis certain


Neck pain post motor vehicle accident.

Patient Data

Age: 60 years
Gender: Female

There are vertical fractures involving the anterior arch of the atlas bilaterally with mild displacement of the fragmented bone anteriorly by 2 mm. No involvement of the posterior elements or lateral masses. Atlanto-occipital alignment is maintained. 

Case Discussion

A displaced segmental fracture of the anterior arch is rare and is referred to as a “plough” fracture. Forward thrust of the dens from hyperextension at the craniocervical junction acts to shear off the anterior arch of the C1, a mechanism that has been likened to a plough. This fracture is considered to be the bony equivalent of an atlas transverse ligament rupture and therefore is unstable.

This case represents a Gehweiler type 1 atlas fracture.

Case co-author: Rehana Jaffer, MD, FRCPC

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