Flexion teardrop fracture

Flexion teardrop fractures represent a fracture pattern occurring in severe axial/flexion injury of the cervical spine. They are important to recognize because they indicate extensive underlying ligamentous injury and spinal instability. Associated spinal cord injury is common, especially anterior cervical cord syndrome and quadriplegia.

They should not be confused with extension teardrop fractures, which tend to occur higher within the cervical spine and are considered less severe injuries ¹.

Pathology

Mechanism

The injury typically occurs from severe flexion and compression forces (e.g. diving impact, deceleration during motor vehicle collision). With the most severe injuries, there is structural failure in a characteristic pattern:

• shearing/compression fracture along the anterior vertebral body, isolating a (classically) triangular anterior fragment and with rupture of anterior longitudinal ligament
• fracture continuation through the vertebral inferior subchondral plate (endplate), with shearing/rotational injury of the posterior discoligamentous complex and rupture of posterior longitudinal ligament ¹
• forward rotational force causing distraction along posterior elements and tensile rupture of posterior ligaments (e.g. ligamentum flavum, interspinous)
• variable posterior translocation of the lower cervical column in relation to the upper column ^1,2, often with focal kyphotic deformity.  These features, together with possible retropulsed fracture fragments, correspond to the characteristic anterior spinal cord injury

The overall extent of injury is quite variable. Less severe injuries manifest as incomplete patterns, and are less associated with neurological injury ¹.

Radiographic features

Flexion teardrop fractures most commonly occur at mid/lower cervical spine, specifically at C4, C5, or C6 ^1,2.

The most characteristic findings include:

• fracture of the anteroinferior lip of vertebral body
  • classically a triangular fragment (teardrop sign)
  • larger fragments may not appear triangular
  • anterior fragment often minimally displaced
• posterior displacement of the posterior vertebral body relative to the intact inferior cervical column

Depending on the fracture severity, additional findings may include:

• variable fracture of the vertebral body
  • loss of anterior height of the vertebral body
  • sagittal fracture through the vertebral body
  • vertebral body rotation with an AP diameter that appears smaller than on other levels
• abnormal spinal alignment - often less apparent if imaging occurs after traction is performed
  • cervical kyphosis
  • disruption of the spinolaminar line
  • widening of interspinous processes
  • anterior dislocation of the facet joints
• intervertebral disc space narrowing (discoligamentous injury)
  • more common inferior to the posterior vertebral body fragment versus anterior fragment
• additional spinal fractures at other levels
  • burst-type ²

Radiology Report

Given the spectrum of injury that occurs with flexion teardrop fracture, it is less important to label the findings as "flexion teardrop" and more important to draw attention to clinically-relevant information. The following should receive comment, whether present or absent:

• degree of posterior translocation of lower versus upper spinal column at the level of injury
  • strongly correlates with degree of neurological injury ^1,2
• retropulsion of bone fragments which narrow spinal canal
• evidence of posterior ligamentous rupture
  • keep in mind, interspinous interval may be normal or even decreased following traction-immobilization
• other spinal fractures

Treatment and prognosis

Treatment and prognosis of flexion teardrop fractures is variable, and depends on the degree of injury.  Due to the associated injury of both osseous and ligamentous structures, this fracture is usually unstable with almost all patients requiring decompression and internal fixation.

The long-term prognosis of this injury mostly depends on the degree of neurological injury.  Although milder cord injuries may be asymptomatic or have few neurological sequelae, injury with posterior column translocation in particular is associated with paralysis and quadriplegia ¹.

Differential diagnosis

The 'teardrop' fracture appearance is non-specific. A similar-appearing anteroinferior fracture fragment may occur inextension teardrop fracture; however, the extension fractures more commonly occur in the upper cervical spine (e.g. C2), and have no associated posterior translocation of the posterior vertebral body. They are considered less severe and often managed conservatively ¹.

Practical points

• further evaluation of the spinal cord by MRI should be performed to investigate possible cord injuries
• CT angiography may be indicated to screen for blunt cerebrovascular injury (BCVI).

See also

• teardrop (disambiguation)