Subaxial cervical trauma

1. High-Yield Summary

• Subaxial cervical spine trauma encompasses traumatic osseous and disco-ligamentous injuries spanning the third cervical vertebra (C3) through the first thoracic vertebra (T1) cervicothoracic junction, accounting for approximately 65% to 75% of all cervical spine fractures and over 75% of cervical spinal cord injuries.
• Clinical decision-making hinges upon objective evaluation of three structural and functional parameters: injury morphology (compression, distraction, translation/rotation), integrity of the disco-ligamentous complex (DLC), and neurological status, codified in the Subaxial Injury Classification (SLIC) system and the AOSpine Subaxial Injury Classification.
• Emergent thin-slice multidetector computed tomography (CT) with 1 mm sagittal and coronal reformations is the primary diagnostic gold standard; magnetic resonance imaging (MRI) is mandatory to evaluate DLC disruption, cord contusion or compression, and traumatic disc herniation prior to surgical stabilization or closed reduction in obtunded patients.
• Emergent closed skeletal traction reduction is indicated for awake, evaluable patients presenting with bilateral or unilateral jumped/locked facet dislocations; if the patient is obtunded, unevaluable, or if closed reduction fails, emergent MRI and operative reduction are required.
• In complete or incomplete traumatic cervical spinal cord injury (SCI), surgical decompression and rigid stabilization within 24 hours (and ideally within 8 to 12 hours) significantly improves neurologic recovery, combined with strict mean arterial pressure (MAP) augmentation targets of 85 to 90 mmHg for 5 to 7 days in the intensive care unit.

2. Anatomy

The subaxial cervical spine (C3–C7) possesses unique morphological and biomechanical characteristics distinguishing it from the craniocervical junction (occiput–C2) and the rigid thoracic spine. The subaxial vertebrae feature small vertebral bodies with superior concave and inferior convex endplates, flanked posterolaterally by the uncinate processes (joints of Luschka) that provide inherent resistance against lateral translation and axial rotation.

The posterior elements consist of robust pedicles projecting posterolaterally, paired articular pillars with facet joints oriented at a 45-degree angle in the sagittal plane (shingle configuration), broad laminae, and bifid spinous processes. The 45-degree inclination of the facet joints facilitates substantial flexion, extension, and lateral bending, but renders the subaxial spine vulnerable to translation, subluxation, and dislocation under distractive or shearing vectors.

The spinal canal in the subaxial spine is triangular, with a normal anteroposterior diameter of 17 to 18 mm at C3–C5. Congenital or degenerative canal stenosis (Pavlov-Torg ratio < 0.8 or absolute canal diameter < 13 mm) substantially amplifies the risk of traumatic spinal cord injury following low-energy hyperextension mechanisms.

Neurovascular Danger Zones

• Vertebral Arteries: Ascend through the transverse foramina of C6 through C1, situated immediately anterior to the exiting cervical spinal nerve roots and lateral to the uncovertebral joints. Transverse foramen fractures, facet dislocations, and laterally displaced burst fragments place the vertebral artery at acute risk of intimal dissection, pseudoaneurysm, thrombosis, or transection (incidence up to 20% to 35% in subaxial facet dislocations).
• Cervical Spinal Nerve Roots: Exit through the neural foramina anterosuperior to the superior articular process of the lower vertebra and posteroinferior to the pedicle of the upper vertebra. The C5 through T1 roots contribute to the brachial plexus. Unilateral facet subluxation or fracture frequently causes nerve root impingement, presenting as acute radiculopathy.
• Cervical Spinal Cord: Occupies the spinal canal surrounded by the thecal sac and epidural venous plexus. The anterior spinal artery travels in the anterior median fissure, supplying the anterior two-thirds of the cord; compression by retropulsed bone fragments or extruded disc material induces anterior cord ischemia.
• Sympathetic Trunk: Traverses vertically along the anterior surface of the longus colli fascia. Excessive lateral retraction of the longus colli muscle during anterior surgical exposure risks iatrogenic Horner syndrome (ptosis, miosis, anhidrosis).
• Recurrent Laryngeal Nerve (RLN): In the anterior approach, the right RLN loops around the subclavian artery and enters the tracheoesophageal groove with a more variable oblique path than the left RLN (which loops around the aortic arch). Over-retraction or direct pressure from retractor blades can induce vocal cord palsy and hoarseness.

Surgical Internervous Planes

Anterior surgical access utilizes the classic Smith-Robinson approach through the plane between the sternocleidomastoid muscle and carotid sheath laterally (innervated by the spinal accessory nerve, CN XI) and the strap muscles, trachea, and esophagus medially (innervated by the ansa cervicalis). Posterior surgical exposure utilizes the true avascular midline raphe between bilateral paraspinal muscles (trapezius, splenius capitis, semispinalis cervicis), with subperiosteal dissection preserving the lateral neurovascular bundles.

3. Pathogenesis and Biomechanics

Subaxial cervical trauma results from high-energy mechanical vectors applied to the head and torso that exceed the physiologic tensile, compressive, or shearing limits of the cervical osteoligamentous envelope. Biomechanically, the subaxial spine is divided into structural columns based on the White and Panjabi stability criteria and modern three-column constructs:

• Anterior Column: Anterior longitudinal ligament (ALL) and anterior two-thirds of the vertebral body and annulus fibrosus. Resists hyperextension forces.
• Middle Column: Posterior one-third of the vertebral body, posterior annulus fibrosus, and posterior longitudinal ligament (PLL). Disruption allows retropulsion of osseous fragments into the spinal canal.
• Posterior Column (Posterior Tension Band / DLC): Facet joints with their fibrous capsules, ligamentum flavum, interspinous ligaments, supraspinous ligament, and nuchal ligament complex. Resists hyperflexion and distraction forces.

Injury vectors dictate distinct injury morphologies:

• Hyperflexion-Distraction: Compresses the anterior column while applying catastrophic tensile failure to the posterior tension band. Results sequentially in interspinous ligament rupture, facet subluxation, facet perch, and facet dislocation (unilateral or bilateral). In bilateral facet dislocations, the superior vertebral body translates anteriorly greater than 50% relative to the inferior vertebra, with complete disruption of the ALL, disc, PLL, and posterior ligamentous complex.
• Vertical Compression (Axial Loading): Transmits direct axial load through the vertebral body without significant flexion or extension. Leads to burst fractures with comminution of both endplates and centripetal retropulsion of the posterosuperior fragment into the spinal canal.
• Hyperextension-Distraction / Extension-Compression: Compresses the posterior elements (laminar and facet fractures) while creating tensile avulsion of the anterior longitudinal ligament and disc space. In patients with diffuse idiopathic skeletal hyperostosis (DISH) or ankylosing spondylitis, extension mechanisms create long-lever-arm “chalk stick” three-column fractures with profound instability.
• Flexion-Compression: Generates anterior vertebral body wedge compression or teardrop fractures, wherein a characteristic triangular anteroinferior fragment separates while the posterior vertebral body retropulses into the thecal sac.

4. Natural History and Epidemiology

Subaxial cervical trauma displays a bimodal demographic distribution:

• High-Energy Young Cohort (Ages 18–35): Predominantly males involved in motor vehicle collisions (40% to 50%), contact sports, diving accidents, and high-velocity falls. These patients exhibit high rates of severe ligamentous disruption, translation/dislocation, polytrauma, and complete neurological deficits.
• Low-Energy Elderly Cohort (Ages 65 and older): Equal sex distribution, typically resulting from low-energy ground-level falls. Underlying cervical spondylotic myelopathy, osteopenia, or ankylosing spinal disorders predispose this population to acute spinal cord injury (e.g., central cord syndrome) even with minimal or occult osseous disruption.

The natural history of untreated unstable subaxial injuries is characterized by progressive sagittal kyphotic deformity, chronic intractable axial pain, delayed or non-healing pseudoarthrosis, and secondary neurological deterioration resulting from chronic tethering of the spinal cord over kyphotic apex bone bars or disc protrusions. In acute cervical spinal cord injury, overall in-hospital mortality averages 7% to 10%, heavily driven by respiratory complications (pneumonia, ventilatory failure due to diaphragmatic or intercostal paralysis), neurogenic shock, and thromboembolism.

5. Clinical Presentation and Physical Examination

History

Initial assessment must strictly follow Advanced Trauma Life Support (ATLS) principles, establishing airway, breathing, and hemodynamic stability with rigid cervical collar immobilization. History should elucidate:

• Exact vector and magnitude of trauma (e.g., rollover collision, ejection, shallow water diving, fall height).
• Transient or persistent sensory loss, weakness, or paresthesias (“burning hands”, numbness) at the scene.
• Neck pain severity, focal radicular radiation into specific upper extremity dermatomes, and breathing difficulty.
• Pre-existing spinal conditions, such as ankylosing spondylitis, DISH, rheumatoid arthritis, or prior cervical fusions.

Physical Examination

A meticulous neurological and musculoskeletal examination must be documented using standardized assessment tools:

• Spine Inspection and Palpation: With inline spinal precautions maintained, log-roll the patient to inspect the posterior cervical spine for ecchymosis, lacerations, step-off deformity, or a palpable interspinous gap (indicative of posterior tension band disruption).
• Neurological Motor Staging (ISNCSCI / ASIA Protocol): Test all ten paired key muscle groups graded 0 to 5: C5 (elbow flexors: biceps, brachialis), C6 (wrist extensors: extensor carpi radialis longus/brevis), C7 (elbow extensors: triceps), C8 (finger flexors: flexor digitorum profundus to middle finger), and T1 (finger abductors: abductor digiti minimi).
• Sensory Staging: Test pinprick and light touch across key subaxial dermatomes (C3 supraclavicular fossa, C4 acromioclavicular joint, C5 lateral antecubital fossa, C6 thumb, C7 middle finger, C8 little finger, T1 medial antecubital fossa).
• Sacral Sparing and Anorectal Examination: Mandatory evaluation of voluntary anal sphincter contraction (S4–S5 motor), deep anal sensation, and perianal pinprick/light touch sensation. The presence of any sacral sparing distinguishes an incomplete injury (ASIA B, C, or D) from a complete injury (ASIA A).
• Bulbocavernosus Reflex: Squeeze the glans penis or clitoris, or apply traction on an indwelling Foley catheter while palpating the anal sphincter. Absence of the reflex confirms spinal shock; neurological prognostication cannot be reliably established until the bulbocavernosus reflex returns (typically within 24 to 48 hours).
• Incomplete Cord Syndrome – Central Cord: Disproportionately greater motor impairment in upper extremities compared to lower extremities, variable sensory preservation, and bladder dysfunction; classically seen in hyperextension injuries in stenotic elderly patients.
• Incomplete Cord Syndrome – Anterior Cord: Loss of motor function, pain, and temperature sensation below the lesion with preserved proprioception and vibratory sense (dorsal columns); typically caused by anterior spinal artery occlusion or anterior retropulsed bone/disc fragments.
• Incomplete Cord Syndrome – Brown-Séquard: Hemisection of the cord producing ipsilateral motor deficit and proprioception loss, with contralateral loss of pain and temperature sensation 1 to 2 levels below the lesion.

6. Imaging and Diagnostic Studies

Clinical Clearance Protocols

In alert, stable trauma patients, validated decision rules guide whether cervical spine imaging is required:

• NEXUS Criteria: Cervical imaging is unnecessary if the patient meets all 5 low-risk criteria: (1) no midline cervical tenderness, (2) no focal neurological deficit, (3) normal alertness (GCS 15), (4) no intoxication, and (5) no painful distracting injury (sensitivity 99.6%, negative predictive value 99.9%).
• Canadian C-Spine Rule: Evaluates high-risk factors (age > 65, dangerous mechanism, paresthesias), low-risk factors permitting range of motion assessment (simple rear-end collision, sitting position in ED, ambulatory at any time, delayed onset neck pain, absence of midline tenderness), and ability to actively rotate neck 45 degrees bilaterally (sensitivity 99.4%, specificity 45.1%).

Multidetector Computed Tomography (CT)

Thin-slice multidetector CT (slice thickness <= 1 mm) from the skull base to T1 with sagittal, coronal, and 3D reformations is the primary gold standard diagnostic modality in blunt trauma, surpassing plain radiography with a sensitivity exceeding 98%. Key CT imaging parameters to evaluate:

• Sagittal Alignment: Disruption of the anterior vertebral line, posterior vertebral line, spinolaminar line, and tips of the spinous processes. Anterior translation > 3.5 mm or relative sagittal angulation > 11 degrees signifies mechanical instability (White-Panjabi criteria).
• Facet Joint Articulation: Inspect facet joints for “naked” or “perched” facets, diastasis (> 2 mm), or frank dislocation. A perched facet shows < 50% overlap of articular surfaces; locked facets show complete loss of articulation with the inferior articular process of the cephalad vertebra resting anterior to the superior articular process of the caudal vertebra.
• Vertebral Body Morphology: Assess for loss of anterior vertebral body height, sagittal vertical split fractures, or retropulsion of the posterosuperior cortex into the spinal canal.
• Transverse Foramen Integrity: Any fracture traversing or abutting the transverse foramen warrants immediate CT angiography (CTA) of the neck to evaluate vertebral artery dissection, pseudoaneurysm, or occlusion.

Magnetic Resonance Imaging (MRI)

MRI is the definitive imaging study for soft tissue pathology, disco-ligamentous integrity, and neural elements. T1-weighted, T2-weighted, and short tau inversion recovery (STIR) sequences are essential:

• Disco-Ligamentous Complex (DLC): High signal intensity or disruption on STIR/T2 imaging in the interspinous ligament, ligamentum flavum, or posterior longitudinal ligament confirms posterior tension band failure.
• Traumatic Disc Herniation: Assesses for extruded disc fragments located behind the translating vertebral body. Identification is critical in jumped facets, as closed reduction of a locked facet in the presence of a large extruded disc fragment carries a risk of catastrophic spinal cord compression during reduction.
• Spinal Cord Parenchyma: Identifies focal cord compression, intramedullary edema (high T2 signal), and cord hemorrhage (central low T2 signal surrounded by hyperintense edema). Intramedullary hemorrhage carries a poor prognosis for motor recovery.

7. Classification Systems

Validated classification systems guide clinical and operative decision-making by categorizing injury morphology, ligamentous stability, and neurological compromise.

Subaxial Injury Classification (SLIC) System

The SLIC system assigns numerical scores based on three independent clinical categories: morphology, disco-ligamentous complex (DLC) integrity, and neurological status. Total score determines management: score < 4 indicates nonoperative treatment, score = 4 is equivocal (surgeon preference), and score >= 5 indicates operative stabilization.

AOSpine Subaxial Cervical Spine Injury Classification

The AOSpine classification integrates vertebral body fracture morphology (Type A to C), facet injury hierarchy (F1 to F4), neurological status (N0 to Nx), and clinical modifiers (M1 to M4):

8. Treatment and Management Algorithms

Medical and Critical Care Management

Immediate resuscitation of acute cervical trauma patients requires aggressive neurocritical care protocols:

• Hemodynamic Augmentation: Maintain mean arterial pressure (MAP) between 85 and 90 mmHg for 5 to 7 days post-injury using volume resuscitation and vasopressors (norepinephrine or phenylephrine) to maintain spinal cord perfusion pressure and combat neurogenic shock (hypotension with bradycardia from loss of sympathetic vascular tone).
• High-Dose Methylprednisolone: The routine administration of high-dose corticosteroids (NASCIS protocol) is no longer recommended as standard of care by AANS/CNS guidelines due to lack of verified functional benefit and significant morbidity (gastrointestinal hemorrhage, severe wound infections, sepsis, pulmonary embolism).
• Airway Management: Urgent intubation via video laryngoscopy or flexible fiberoptic bronchoscopy with manual in-line stabilization (MILS) is indicated for patients with ascending cervical cord edema, high subaxial injury (C3–C5 compromising phrenic nerve function), or respiratory compromise.

Nonoperative Immobilization

Nonoperative treatment is restricted to mechanically stable injuries (SLIC < 4, AOSpine Type A0–A2, non-displaced spinous process or laminar fractures, stable facet avulsions F1):

• Rigid Cervical Orthosis (Miami J / Aspen Collar): Prescribed for 6 to 12 weeks for isolated stable compression fractures (A1), non-displaced uncinate fractures, and stable un-displaced facet fractures. Serial standing lateral radiographs are obtained at 1, 2, and 6 weeks to rule out occult ligamentous insufficiency and progressive kyphosis.
• Halo-Vest Immobilization: Historically used for complex cervical injuries, halo-vest application is now rarely indicated in subaxial trauma due to high complication rates (pin loosening, pin site infection, loss of reduction, dysphagia, respiratory restriction in elderly patients). It remains an alternative when medical comorbidities preclude operative intervention or as a temporary bridge.

Closed Skeletal Traction Reduction

Closed skeletal traction with Gardner-Wells tongs or a halo ring is indicated for emergent reduction of unilateral or bilateral facet dislocations in an alert, cooperative patient:

• Protocol: Place pins 1 cm above the pinna, in line with the external auditory meatus, below the equator of the skull. Begin with 10 to 15 lbs of axial traction and add 5 to 10 lbs incrementally every 10 to 15 minutes, up to a typical maximum of 10 lbs per vertebral level (e.g., up to 50–60 lbs for C5–C6), maintaining neck flexion for locked facets until the facets uncouple, followed by gentle extension.
• Serial Surveillance: Neurological exam and lateral radiographs must be repeated after each weight increment. Traction must be stopped immediately if neurological status deteriorates or if overdistraction (> 10 mm disc space widening) occurs.
• Obtunded / Comatose Patients: Closed traction in unevaluable patients remains controversial; emergent MRI is strongly recommended prior to closed or open reduction to rule out large disc herniation retropulsed into the canal.

Operative Interventions

Surgical goals include neural decompression, anatomic realignment, restoration of sagittal balance, and rigid biomechanical stabilization:

• Anterior Cervical Discectomy and Fusion (ACDF): First-line approach for facet dislocations with traumatic disc herniation, anterior column disruption, or anterior compression without extensive vertebral comminution. Allows complete disc excision, anterior cord decompression under direct vision, distraction-assisted facet reduction via Caspar pins, and stable anterior plate fixation.
• Anterior Cervical Corpectomy and Fusion (ACCF): Indicated for burst fractures (A3/A4) with greater than 50% loss of vertebral height, canal compromise > 30% to 50%, or severe endplate comminution. The vertebral body is resected, followed by reconstruction with an expandable cage or structural mesh cage filled with autograft/allograft, backed by rigid anterior plate fixation.
• Posterior Cervical Instrumented Fusion: Utilizes lateral mass screws (Magerl or Roy-Camille trajectories for C3–C6) and pedicle screws (at C7 and T1) connected by longitudinal rods. Indicated for posterior tension band disruptions (B2), irreducible locked facets requiring open facetectomy/levering, floating lateral masses (F3), or ankylosing spine fractures.
• Combined 360-Degree Circumferential Fusion: Required for severe three-column instability, gross translation (Type C), ankylosing spondylitis fractures, severe osteoporosis, or when corpectomy spanning more than two levels is performed in the presence of posterior column deficiency.
• Timing of Surgical Decompression: The landmark STASCIS trial established that early surgical decompression (= 2 ASIA grade conversion at 6 months) compared to delayed intervention. Current consensus supports decompression within 8 to 12 hours whenever feasible.

9. Outcomes

Surgical intervention for subaxial cervical trauma yields dependable osseous union rates exceeding 95% with modern anterior cervical plates and posterior lateral mass/pedicle screw instrumentation. Functional recovery depends heavily upon the initial ASIA Impairment Scale (AIS) grade and timing of decompression:

• Complete SCI (AIS A): Long-term conversion to functional motor status remains low (< 5% to 10% recover ambulatory capacity); however, recovery of one or two caudal motor root levels (e.g., C5 to C6 or C7) provides vital upper extremity independence, including self-feeding and wheelchair transfers.
• Incomplete SCI (AIS B, C, D): Incomplete injuries demonstrate substantially higher recovery potential, with 60% to 80% of AIS C and D patients achieving ambulatory capacity following timely surgical decompression and structured rehabilitation.
• Unilateral Facet Fractures: Larkin et al. demonstrated in a meta-analysis that surgical stabilization of unilateral subaxial facet fractures achieves superior fusion rates (96.2% vs 67.5%), lower rates of treatment failure (2.1% vs 21.4%), and lower late kyphosis compared to nonoperative collar or halo treatment.
• Patient-Reported Outcomes: Validated measures including the Neck Disability Index (NDI) and SF-36 demonstrate good-to-excellent functional recovery in patients with anatomically restored cervical lordosis and absence of chronic radicular compression.

10. Complications

Complications associated with subaxial cervical trauma and its surgical management span immediate, early postoperative, and late categories:

11. Pearls and Pitfalls

Diagnostic and Preoperative Pearls

• The Overlooked Cervicothoracic Junction: Fractures or dislocations at C7–T1 are frequently obscured on lateral plain radiographs by overlapping shoulder shadows. Never clear a cervical spine without visualization down to the T1 superior endplate on 1 mm thin-cut CT imaging.
• Beware the Ankylosed Spine: In patients with ankylosing spondylitis or DISH, minor ground-level falls can create unstable three-column trans-osseous “chalk-stick” fractures. Always obtain whole-spine CT and MRI if a patient with an ankylosed spine complains of new neck or back pain.
• Vascular Screening: Always perform CTA of the neck when fractures involve the transverse foramina, when facet subluxation or dislocation is present, or when unexplained neurological deficits occur that do not match the spinal level.

Intraoperative and Technical Pitfalls

• Endotracheal Tube Cuff Pressure: Always release and reinflate the endotracheal tube cuff after placing anterior self-retaining retractors; elevated mucosal pressures transmitted through the retractor blades cause ischemic injury to the recurrent laryngeal nerve.
• Anterior Discectomy Before Reduction: In jumped facets with an unknown MRI status or proven disc herniation, never attempt forceful closed or open posterior reduction without first performing an anterior cervical discectomy to prevent pushing an extruded disc fragment into the spinal cord.
• Lateral Mass Screw Angulation: During posterior lateral mass instrumentation (Magerl technique), drill 25 degrees lateral and parallel to the superior articular facet (approximately 30 degrees cephalad) to ensure the screw tip exits superior and lateral to the vertebral artery and exiting nerve root.

12. Controversies in Subaxial Trauma

Pre-Reduction MRI vs Immediate Closed Traction in Locked Facets

A longstanding debate centers on whether an emergent MRI is mandatory prior to closed skeletal traction reduction in awake patients with facet dislocations. Proponents of mandatory pre-reduction MRI cite the risk of neurologic deterioration from herniation of a traumatic disc into the canal during reduction (reported incidence of disc extrusion up to 30% to 50%). Conversely, proponents of immediate closed reduction argue that rapid restoration of canal diameter and spinal realignment in awake, alert patients under continuous serial examination provides superior cord protection and avoids delays of several hours in magnetic resonance suites. Current guidelines endorse immediate closed traction for awake, fully cooperative patients with serial neurological exams, whereas unevaluable, obtunded, or polytrauma patients should undergo MRI prior to reduction.

Anterior vs Posterior vs Circumferential Approach for Displaced Facets

Debate persists regarding the optimal surgical approach for facet subluxations and dislocations. The anterior approach (ACDF) affords direct decompression of traumatic disc herniations, lower surgical site infection rates, and less postoperative neck pain; however, anterior reduction of locked facets can be technically demanding and carry a risk of failure if the facets are heavily locked. The posterior approach allows direct visualization and facile unlocking of the articular facets with powerful tension-band screw fixation, but does not address anterior disc herniations and carries higher wound infection rates. Combined circumferential 360-degree fusion provides the highest biomechanical stability and is indicated when severe anterior vertebral comminution accompanies posterior tension band disruption.

13. Evidence-Based Synthesis

Modern clinical decision-making is grounded in high-quality randomized controlled trials and prospective registry analyses, corroborated by seminal biomechanical and anatomical descriptions.

14. References

• Joaquim AF, Appenzeller S. Cervical spine involvement in rheumatoid arthritis–a systematic review. Autoimmun Rev. 2014. doi:10.1016/j.autrev.2014.08.014 [Level I: Systematic Review / Meta-Analysis]
• Larkin CJ, Abecassis ZA, Yerneni K et al. Surgical versus conservative treatment of unilateral subaxial non-subluxed facet fractures: A systematic review and meta-analysis. Clin Neurol Neurosurg. 2020. doi:10.1016/j.clineuro.2020.106280 [Level I: Systematic Review / Meta-Analysis]
• Sadeghi-Naini M, Yousefifard M, Ghodsi Z et al. In-hospital mortality rate in subaxial cervical spinal cord injury patients: a systematic review and meta-analysis. Acta Neurochir (Wien). 2023. doi:10.1007/s00701-023-05720-5 [Level I: Systematic Review / Meta-Analysis]
• E.G. Meinberg, Julie A. Agel, CS Roberts et al. Fracture and Dislocation Classification Compendium—2018. Journal of Orthopaedic Trauma. 2017. doi:10.1097/bot.0000000000001063 [Level V (Expert Conceptual Review): Seminal Conceptual / Observational Study]
• Beverly C. Walters, Mark N. Hadley, R. John Hurlbert et al. Guidelines for the Management of Acute Cervical Spine and Spinal Cord Injuries. Neurosurgery. 2013. doi:10.1227/01.neu.0000430319.32247.7f [Level IV (Prognostic / Case Series): Seminal Conceptual / Observational Study]
• Vaccaro AR, Lehman RA, Hurlbert RJ et al. A new classification of subaxial cervical spine trauma: the subaxial injury classification system. Spine (Phila Pa 1976). 2007. doi:10.1097/BRS.0b013e3181557b92 [Level V (Expert Consensus / Validation): Consensus Classification & Diagnostic Validation]
• Fehlings MG, Vaccaro A, Wilson JR et al. Early versus delayed decompression for traumatic cervical spinal cord injury: results of the Surgical Timing in Acute Spinal Cord Injury Study (STASCIS). PLoS One. 2012. doi:10.1371/journal.pone.0032037 [Level II (Prospective Comparative): Prospective Multicenter Comparative Cohort]
• Vaccaro AR, Kepler CK, Koerner JD et al. AOSpine Subaxial Cervical Spine Injury Classification System. Global Spine J. 2015. doi:10.1055/s-0035-1554199 [Level V (Expert Consensus / Classification): International Consensus Classification System]

15. Master Class Pro-Tip

When performing an anterior reduction for locked facet dislocations, place Caspar distraction pins in the center of the adjacent vertebral bodies parallel to the respective endplates. Apply gentle axial distraction while placing a small Cobb elevator into the collapsed disc space to leverage the superior vertebra posteriorly. If resistance persists, do not exert excessive levering force against the spinal cord; instead, rotate the operating table 10 degrees to place the patient in reverse Trendelenburg, ensure complete release of the bilateral uncinate ligaments and posterior longitudinal ligament, and apply gentle manual trans-cervical counter-pressure. If anterior reduction fails after two controlled attempts, proceed without hesitation to a posterior exposure to directly unlock the facet joints under direct visualization rather than risking iatrogenic vertebral body fracture or cord compression.

Master Class Surgical Pearl: Direct Anatomic Reduction and Vertebral Artery Safeguards in Subaxial Trauma