Subaxial Cervical Fractures¶

Overview¶

Subaxial cervical spine fractures involve the vertebrae from C3 through C7. This region is the most mobile segment of the cervical spine and is a common site of traumatic injury, particularly at the C5–C6 and C6–C7 levels. The subaxial spine differs biomechanically from the upper cervical spine, with intervertebral discs, uncovertebral joints, and obliquely oriented facets contributing to both mobility and vulnerability to injury.

Mechanisms and Injury Patterns¶

Subaxial cervical injuries are broadly classified by the direction and type of force applied:

Flexion Injuries¶

• Anterior wedge compression fracture — Loss of anterior vertebral body height with intact posterior cortex and posterior elements. Stable if mild.
• Flexion teardrop fracture — A triangular fragment avulses from the anteroinferior vertebral body with disruption of the posterior ligamentous complex and disc. Highly unstable with a strong association with anterior cord syndrome.
• Bilateral facet dislocation — Complete disruption of the facet capsules, disc, and posterior ligaments. The superior vertebra translates anteriorly by 50% or more of the AP diameter of the vertebral body. Highly unstable.
• Unilateral facet dislocation — Disruption of one facet capsule with the facet "perched" or "locked" anterior to the inferior articular process. Anterior translation is typically 25% or less.

Extension Injuries¶

• Extension teardrop fracture — A triangular fragment avulses from the anteroinferior vertebral body due to avulsion by the anterior longitudinal ligament. Most common at C2. Generally stable.
• Hyperextension dislocation — Disruption of the anterior longitudinal ligament and disc without a fracture. May present with a normal-appearing radiograph despite significant cord injury (central cord syndrome). MRI is essential.
• Lamina and spinous process fractures — Posterior element fractures from hyperextension with compression.

Axial Loading¶

• Burst fracture — Comminution of the vertebral body with retropulsion of fragments into the spinal canal. Results from axial compression.

Lateral Flexion¶

• Unilateral lateral mass or pillar fracture — Fracture of the articular pillar on one side, often with rotation.

Imaging Evaluation¶

CT¶

CT with sagittal and coronal reformats is the primary diagnostic modality:

• Vertebral body fractures (compression, burst, teardrop)
• Facet alignment — subluxation, perch, dislocation, or fracture
• Lamina and spinous process fractures
• Canal compromise from retropulsed fragments

MRI¶

MRI is essential for evaluating:

• Disco-ligamentous complex (DLC) integrity — critical for SLIC scoring
• Spinal cord signal (edema, hemorrhage, compression)
• Epidural hematoma
• Disc herniation (traumatic)
• Posterior ligamentous complex disruption

Classification¶

The SLIC (Subaxial Cervical Spine Injury Classification) and AO Spine Subaxial Cervical Classification are the primary systems used. SLIC scoring incorporates morphology, DLC integrity, and neurological status to guide management decisions.

Key Points¶

• The subaxial cervical spine (C3–C7) is the most commonly injured cervical region, particularly at C5–C7
• Flexion teardrop fractures and bilateral facet dislocations are highly unstable injuries with high rates of neurological deficit
• Extension injuries may present with a normal-appearing CT despite significant cord injury — MRI is essential
• CT characterizes bony injury; MRI evaluates the DLC, spinal cord, and discs
• SLIC scoring guides management decisions

References¶

1. Vaccaro AR, Koerner JD, Radcliff KE, et al. AOSpine subaxial cervical spine injury classification system. Eur Spine J. 2016;25(7):2173-2184. https://pubmed.ncbi.nlm.nih.gov/25716661/

2. Spitnale MJ, Grabowski G. Classification in Brief: Subaxial Cervical Spine Injury Classification and Severity Score System. Clin Orthop Relat Res. 2020;478(10):2390-2398. https://pmc.ncbi.nlm.nih.gov/articles/PMC7491911/

3. Schroeder GD, Canseco JA, Patel PD, et al. Establishing the Injury Severity of Subaxial Cervical Spine Trauma: Validating the Hierarchical Nature of the AO Spine Subaxial Cervical Spine Injury Classification System. Spine (Phila Pa 1976). 2021;46(10):649-657. https://pubmed.ncbi.nlm.nih.gov/33337687/

4. Mubark I, Abouelela A, Hassan M, Genena A, Ashwood N. Sub-Axial Cervical Facet Dislocation: A Review of Current Concepts. Cureus. 2021;13(1):e12581. https://pmc.ncbi.nlm.nih.gov/articles/PMC7870112/

5. DiPompeo CM, Das JM. Subaxial Cervical Spine Fractures. In: StatPearls. StatPearls Publishing; 2023. https://www.ncbi.nlm.nih.gov/books/NBK546617/

6. Flanders A, Smithuis R. Cervical injury. The Radiology Assistant. Published November 24, 2008. https://radiologyassistant.nl/neuroradiology/spine/cervical-injury

7. Gaillard F, et al. Flexion teardrop fracture. Radiopaedia. https://radiopaedia.org/articles/flexion-teardrop-fracture-1

Related Articles¶

• Facet Dislocations
• Teardrop Fracture
• SLIC
• Spinal Cord Injury Imaging