Hangman's Fractures

Etiology

Schneider et al coined the term "hangman’s fracture" in 1965. Although the term historically implied a hyperextension and distraction injury, as occurs in judicial hangings, the contemporary mechanism of injury is hyperextension combined with axial loading of the cervical spine.[5] Hangman’s fractures most commonly result from motor vehicle collisions, falls, diving injuries, or contact sports.

Epidemiology

Fractures of the cervical spine occur in 1% to 3% of all trauma cases, of which 9% to 18% involve C2. The incidence of C2 fractures has doubled from 3 per 100,000 to 6 per 100,000 between 1997 and 2014, according to the Swedish National Patient Registry.

Fractures of the odontoid process are more common, representing 35% to 78% of all C2 fractures in the general population and 89% of fractures in adults older than 70. Hangman’s fractures account for 11% to 25% of all C2 fractures.[6] Recent research demonstrates a higher frequency of hangman’s fractures in men, primarily affecting young and middle-aged adults, with a lower incidence in older cohorts.

A study of 216 patients with a mean age of 49.7 years analyzed the geriatric population (18.5%) separately from younger patients and demonstrated a male predominance, with ratios of 3:1 in patients aged 18 to 64 and 2:1 in patients older than 65.[7] An earlier study of 58 patients reported a mean age of 62.7 years (standard deviation 25 years), with a male-to-female ratio of 1:1.2. Motor vehicle accidents were the most common cause of injury in both cohorts.

Pathophysiology

Consideration of the unique anatomy of the atlas-axis complex is vital when managing associated injuries. Unlike the subaxial cervical spine, the C1–C2 complex lacks an intervertebral disc and contains specialized ligaments that support the cranium and provide the largest contribution to cervical rotation. The transverse foramen, which transmits the vertebral artery through the cervical spine, lies in close proximity to the C2 pedicle and pars interarticularis, slightly weakening this region and predisposing it to fracture.

Two hypotheses have been proposed to explain the pathogenesis of hangman’s fracture. The internal gear hypothesis suggests that a trabecular void and the abrupt transition from the bicolumnar to the tricolumnar unit place the isthmus of the axis at increased risk of injury. The leaf spring hypothesis proposes that the C2 pedicle functions as the shackle within the vertebral assembly, representing the structural weak point.

The extension-compression subtype of a hangman’s fracture arises from pincer-like compression of the C2 pedicle between the adjoining articular processes of C1 and C3. The flexion subtype results from bending failure of the pedicle over the fulcrum formed by the superior facet of C3. Flexion-type injuries carry an increased risk of damage to the C2–C3 disc anteriorly and the C1–C2 posterior ligament complex posteriorly.[8]

Multiple grading systems exist for hangman’s fractures. However, the Levine and Edwards classification remains the most widely used.

Levine and Edwards Classification

Angulation in the Levine and Edwards system is measured as the angle between the inferior endplates of C2 and C3. Anterior subluxation of C2 on C3 greater than 3 mm indicates disruption of the C2–C3 intervertebral disc. This grading system does not apply to the pediatric population.[9]

Type 1 fractures involve less than 3 mm of C2 on C3 subluxation, result from axial loading, and are considered stable. Management typically involves a rigid cervical collar.

Type 2 fractures demonstrate C2–C3 disc disruption and posterior longitudinal ligament injury, with subluxation greater than 3 mm and angulation exceeding 11°. Subluxation less than 5 mm requires reduction with axial traction and immobilization in a halo for 6 to 12 weeks, whereas subluxation greater than 5 mm may necessitate surgical intervention. Type 2a fractures exhibit less displacement but greater angular deformity, result from flexion injury, and are unstable. These injuries are not amenable to axial traction and require halo immobilization.

Type 3 fractures are characterized by C2–C3 facet joint dislocation and anterior longitudinal ligament disruption. These unstable injuries may be associated with a neurologic deficit and typically require surgical management.

Francis Grading System

The Francis grading system evaluates hangman’s fractures based on angulation and displacement. Angulation is measured as the degree of anterior deviation from a posterior vertebral line drawn straight from the C3 vertebral body. Displacement is assessed by the magnitude of the anterolisthesis and graded as greater than or less than 3.5 mm.[10]

Type 1 fractures exhibit less than 11° of angulation and less than 3.5 mm of displacement. Type 2 fractures demonstrate greater than 11° of angulation with less than 3.5 mm of displacement. Type 3 fractures show less than 11° of angulation and greater than 3.5 mm of displacement. Type 4 fractures combine greater than 11° of angulation with displacement exceeding 3.5 mm. Type 5 fractures involve complete disruption of the intervertebral disc.

Differences Between Typical and Atypical Fractures

Not all C2 hangman’s fractures may be classified using standard systems. Typical hangman’s fractures result in separation of the anterior elements from the posterior elements of the C2 vertebra, increasing the space available for the spinal cord and reducing the risk of neurologic injury.[11] Meanwhile, atypical hangman’s fractures involve the posterior aspect of the C2 vertebral body rather than the bilateral pars interarticularis, limiting the increase in spinal canal space and elevating the risk of neurologic compromise. Atypical fractures also include variants with unusual fracture or displacement patterns. Coronal vertical fractures affect the posterior aspect of the C2 body.[12] Isolated C2–C3 facet dislocations may also occur.[13] C2–C3 spondylolisthesis can result from injury to the capsular ligament of the facet joint and the posterior spinous ligamentous complex.[14] Atypical hangman's fractures may also involve the pedicles.[15]

History and Physical

Recognition of hangman’s fractures must extend beyond obvious mechanisms, such as motor vehicle collisions and high-impact falls, as low-energy or blunt trauma, particularly in older patients, can produce significant unstable injuries. History should include assessment of fracture risk factors, such as osteoporosis, metastatic disease, or vitamin D deficiency. Physical examination may reveal posterior neck tenderness, radiculopathy, myelopathy, and posterior fossa signs secondary to vertebral artery injury. A comprehensive neurologic examination is required, including cranial nerve status, sensory and motor function, and rectal tone.

Evaluation

Laboratory tests should be obtained as an adjunct to overall medical assessment. Normalized hemoglobin, hematocrit, prothrombin time, partial thromboplastin time, international normalized ratio, and platelet counts are required prior to operative intervention.

Radiography

Evaluation with x-rays provides limited but important information. Proper radiographic technique must capture the cervical spine from the occiput through the C7–T1 disc space, which is essential in the assessment of cervical spine trauma. Lateral, anteroposterior, and open-mouth odontoid views are required. Approximately 93% of cervical spine injuries are visible on combined lateral, anteroposterior, and odontoid radiographs. X-rays are effective for assessing cervical alignment during the acute phase, the postoperative period, and long-term follow-up. Li et al reported that the presence of a posterior vertebral wall fracture with translation of at least 1.8 mm and C2–C3 angulation of at least 5.5° on x-ray predisposes patients with hangman’s fractures to partial neurologic deficit.[16]

Computed Tomography

Computed tomography (CT) is the mainstay of imaging for hangman’s fractures.[17] CT is the preferred modality for determining fracture morphology and evaluating associated C2 injuries (see Image. Three-Dimensional Computed Tomography of a Hangman's Fracture). CT scanning is indicated when clinical suspicion remains high despite unremarkable findings on plain radiography. CT is also critical for preoperative planning when surgical intervention is indicated. However, this imaging technique does not directly assess the spinal cord, soft tissues, or ligamentous structures. Complete evaluation requires dedicated thin-cut CT reconstructions. Noncontrast-enhanced CT is sufficient for assessing bony anatomy and characterizing fractures, and may be combined with CT angiography when evaluating vertebral and vascular anatomy. 

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is essential for assessing soft-tissue injuries, including ligamentous structures, intervertebral discs, spinal cord components, and nerve roots. Noncontrast MRI is particularly useful for determining the acute nature of a fracture when this information is otherwise unknown. T2 signal hyperintensities and STIR (short τ inversion recovery) changes within the dens, ligaments, or surrounding soft tissue can identify critical components of the injury. MRI carries a lower risk than flexion-extension cervical radiography.

The Effendi, Levine, and Francis classifications are based exclusively on static radiographs. Management decisions also depend on the integrity of the C2–C3 disc and the anterior and posterior longitudinal ligaments. MRI provides essential information regarding concurrent instability, which may be indicated by C2–C3 angulation of at least 11°, C2–C3 translation of at least 3.5 mm, the presence of teardrop fractures involving C2 or C3, and association with C2–C3 discoligamentous injury.[18]

Vascular Imaging

Vascular imaging may be indicated in the evaluation of cervical spine fractures. The vertebral artery’s 2nd segment (V2) traverses the transverse foramina of C2 through C6, while the 3rd segment (V3) runs extradurally, exiting the C2 foramen across the sulcus arteriosus, placing it at risk for injury. A series found that 15% of patients with fractures of C1 to C2 sustained vertebral artery injuries, with type III odontoid fractures conferring the greatest risk. Untreated vertebral artery injury carries a stroke rate of 24%. CT angiography may be performed in conjunction with CT fracture imaging, taking kidney function into account. Level III evidence supports screening of patients with fractures involving C1 to C3 using multislice, multidetector CT angiography. Magnetic resonance angiography is not recommended as the sole imaging modality for evaluating the vertebral arteries. First-line investigation with percutaneous angiography is considered overly aggressive.[19][20]

Treatment / Management

Treatment options include conservative management, cervical or halo-vest orthosis, and surgical intervention. Fracture stability and the presence of neurologic deficits aid in determining the appropriate strategy.

External Fixation

A rigid cervical collar constitutes the initial treatment for hangman’s fractures. Nonunion occurs in up to 50% of odontoid fractures but is rare in hangman’s fractures, with approximately 90% achieving healing with immobilization alone. Level III evidence indicates that hangman’s fractures may be initially managed using either halo-vest or rigid collar immobilization, producing a reduction rate of 97% to 100% and a fusion rate of 93% to 100%. External orthoses should be maintained for 8 to 14 weeks. Older patients demonstrate poor tolerance of halo-vest orthosis, making rigid cervical collars the preferred 1st-line management in this group.[21][22][23](B3)

Nonoperative treatment is recommended for extension-type Levine-Edwards type I and type II hangman’s fractures. Flexion-type Levine-Edwards type IIa and type III fractures require surgical intervention.[24](B2)

A systematic review demonstrated that conservative treatment achieves sequentially lower fusion rates, from nearly 100% in Levine-Edwards type I fractures to approximately 30% in type III fractures. This approach is time-consuming and carries a high risk of nonunion. In a study of 625 patients treated with halo-vest immobilization, patients older than 80 years exhibited higher risks of complications, mortality, and readmissions.[25] Another study of 189 patients, 71.1% of whom sustained C2 fractures managed with halos, reported a mortality rate of 8.3%, a treatment failure rate of 10.7%, and a complication rate of 46.3%.[26]

Internal Fixation

Surgical fixation may be indicated in the presence of any of the following:

• Severe angulation of C2 on C3 (Francis II and IV, Levine II)
• Disruption of the C2–C3 disc space (Francis V, Levine II)
• Anterior displacement of C2 greater than 50% on C3
• Inability to establish or maintain alignment with external immobilization
• Nonunion following external immobilization

The primary objective of surgical intervention is to achieve early anatomical stability while preserving maximal cervical range of motion.[27] Abnormal angulations and incomplete reduction compromise biomechanical loading, increasing the risk of persistent neck pain, nonunion, and implant failure. Surgical strategies include halo traction, anterior or posterior standalone fusion, and global anterior-posterior fusion. Internal fixation may be accomplished through anterior approaches or various posterior constructs.

Anterior approach

Anterior cervical discectomy of C2 to C3 and fusion with anterior plating stabilizes the C2 and C3 vertebral bodies. The primary advantage of the anterior approach is preservation of C1 motion, which significantly reduces morbidity compared to posterior fixation.

Posterior approach

Posterior fixation for hangman’s fractures may be achieved using several constructs, including C1–C2 transarticular screws, C1 lateral mass and C2 pedicle screws, C1 lateral mass and C2 pars interarticularis screws, and C1–C2 wiring as an adjunct technique. Fixation may be extended to the C3 lateral mass if disruption of the C2–C3 intervertebral disc or facet joint capsules is present.[28](A1)

Selection of the posterior fixation technique requires comprehensive evaluation by a neurosurgeon or orthopedic spine surgeon, considering factors such as surgeon experience, fracture location, vertebral artery anatomy, biomechanical suitability, and patient-specific anatomical variations. Preoperative vascular imaging is essential to determine the course of the vertebral artery in the V2 and V3 segments. Assessment of overall functional status, medical optimization, and bone health is critical in operative planning. Flexion-type injuries that compromise the posterior ligamentous complex necessitate C1–C2 posterior fixation according to the tension band principle, whereas extension-type injuries require fixation at the C2–C3 level, which may be performed via anterior or posterior approaches.

Levine-Edwards type II fractures are primarily managed with anterior C2–C3 fusion. Levine-Edwards type III fractures may also be treated with anterior C2–C3 fusion if reducible following traction. Irreducible type III fractures typically require posterior fusion and may necessitate global fixation. An anterior standalone approach using an extended cantilever beam technique that includes C4 has demonstrated effective reduction and stability in Levine-Edwards type III hangman’s fractures. Posterior approaches generally provide superior restoration of cervical sagittal balance compared to anterior approaches.[29]

Prerequisites for posterior pars screw fixation include reducing fracture translation to less than 3 mm and maintaining an intact anterior longitudinal ligament. Pars screws in type II fractures should be supplemented with concurrent C3 lateral mass fixation. This technique limits C1–C2 motion and does not address the anterior disc. Anterior fixation is recommended for C2–C3 disc disruption. C3 corpectomy may be required for spinal cord decompression.[30] The accuracy of screw placement may be enhanced using robot-assisted methods and intraoperative navigation systems.[31][32][33] Minimally invasive techniques using tubular retractor systems with neuronavigation have also been described.[34][35](B3)

Some strategies can help improve precision in fracture fixation, protect neurovascular structures, and preserve postoperative cervical mobility. Preoperative angiography allows assessment of the course and integrity of the vertebral artery. Intraoperative risk of arterial injury can be mitigated by utilizing color-coded duplex ultrasound.[36][37] Use of a C2 spinous muscle complex graft, compared with iliac bone, minimizes donor site morbidity and complications.[38] Zero-profile implants reduce dysphagia and preserve motion at the atlantoaxial joint.[39] C2 pedicle reformation using Herbert compression and lag screws maintains cervical mobility.[40][41] Constructs extending to C4 may be required to prevent kyphotic deformity.[42][43] Hangman’s fractures generally demonstrate excellent clinical outcomes, with low risks of mortality and neurologic complications.(B3)

Differential Diagnosis

Differential diagnoses include pseudosubluxation, most commonly occurring at C2 on C3, and congenital spondylosis of C2. The Mach effect should also be considered.

Prognosis

Successful repair of a fractured vertebra may result in an excellent recovery and a favorable long-term prognosis. Some cases require fusion of C2 and C3. Posterior fusion for 3-part fractures of the axis has demonstrated excellent outcomes.[44] In a study of more than 30 patients with hangman’s fractures, 85% achieved full recovery within a year.[45] A retrospective review of older patients with hangman’s fractures reported bony fusion in nearly 90% of cases, reaching 100% when including patients who required surgical intervention after initial fusion failure.[46]

Complications

Complications of hangman’s fractures can be significant and require careful consideration (see Image. Swan Neck Deformity in Neglected Traumatic Spondylolisthesis). A vertebral artery arteriovenous fistula may develop, resulting from traumatic disruption of the arterial wall and abnormal communication with adjacent veins, potentially leading to hemorrhage or ischemia.[47][48] Occlusion or dissection of the vertebral artery constitutes another vascular complication, which can compromise the posterior circulation and increase the risk of stroke.[49][50] Brown-Sequard syndrome may result from hemisection or asymmetric spinal cord injury, producing ipsilateral motor deficits and contralateral sensory loss.[51] Concurrent spinal cord injury is more likely in atypical fractures, as well as Levine-Edwards type IIa and type III fractures, given the greater displacement and instability associated with these patterns, which can result in neurological compromise.

Complications of different management strategies include postoperative self-limiting dysphagia, which has a reported incidence of 22.6% during the 1st week and 9.7% at 3 months, with very few cases being permanent. The risk of dysphagia is higher with anterior plating and minimized with zero-profile implants. Postoperative dysphonia has a reported incidence of 24.5% during the 1st week and 3.8% at 3 months.[52] Intraoperative vertebral artery injury may occur. Halo-related complications include pin-site infections, pin loosening, and restricted neck movements.