What is your diagnosis?

C1 burst fracture, otherwise known as a Jefferson burst fracture, defined as fractures of the anterior and posterior arches of atlas (C1). It is caused by an axial load that forces the occipital condyles into the lateral masses of C1.

• Pearl: This can be a highly unstable fracture that may be associated with neurologic deficits and vertebral artery injury [1]. 
• Pearl: Bone fragments usually spread radially but can occasionally be retropulsed into the spinal canal, causing neurologic deficits [1].

How do you determine stability on imaging?

Stability is determined by the transverse ligament, which maintains positioning of the C2 dens. The following imaging modalities can help assess for injury.

1. Lateral cervical radiographs

Atlantodens Interval (ADI): Distance from posterior aspect of the anterior arch to the anterior aspect of the dens

• Possible transverse ligament injury if ADI > 3mm 

Case courtesy of Dr Andrew Dixon, Radiopaedia.org, rID: 9601. Annotations by author

2. Open mouth odontoid radiographs

If sum of lateral mass displacement is > 7mm, suspect Jefferson fracture and transverse ligament injury

Case courtesy of Dr Andrew Dixon, Radiopaedia.org, rID: 9601. Annotations by author

3. CT: Gold standard to delineate the fracture pattern

• If ADI is > 2mm, suspect transverse ligament injury

Case courtesy of Dr Andrew Dixon, Radiopaedia.org, rID: 9601. Annotations by author

 
4. MRI: Gold standard to assess for transverse ligament injury

What is your management in the ED?

The patient should be placed in a cervical collar and maintained in strict spinal precautions. A spine surgeon should be consulted emergently as guided by institutional protocols. Additional trauma imaging and workup should also be obtained and the patient admitted for further management.

• Pearl: A CT angiography of the neck should also be ordered to assess for vertebral artery injury, which, if present, will require anticoagulation in discussion with your consultants.

How is this definitively treated?

Treatment depends on the integrity of the transverse ligament

1. If intact -> hard collar [2]

2. If torn -> C1-2 fusion or occipitocervical fusion (C0-2)

3. If bony avulsion on the insertion point of the transverse ligament -> halo vest