The Thoracolumbar Spine

1

Imaging assessment

• Radiographic examination

  • AP

  • Lateral views

• Computed tomography (CT)

  • Axial

  • Reformatted images

    • Coronal

    • Sagittal

    • 3-D

2

Anatomic features, biomechanics, and forces of injury

• Anatomy

• Biomechanics

  • Denis three-column concept

• Forces of injury

  • Flexion

  • Extension

  • Compression

  • Distraction

  • Shearing

  • Rotation

3

Common forms of fracture and fracture-dislocations in adults

• Fracture

  • Vertebral body

    • Anterior wedged compression

    • Burst

    • Chance (seat-belt)

    • Flexion-distraction

    • Extension

  • Vertebral appendage

    • Transverse process

    • Spinous process

• Fracture-dislocation

  • Shearing

  • Flexion-distraction

4

Multilevel spinal injury

• Definition

  • Multiple spinal fractures at discontiguous levels

• Incidence dependent on means of examination

  • Radiography 5% to 7%

  • CT 15% to 20%

  • MRI up to 50%

• Patterns of primary and secondary injuries

  • Upper cervical spine and lower cervical spine

  • Lower cervical spine and lumbar spine

  • Thoracolumbar junction and lower lumbar spine

  • Mid-thoracic spine and cervical and/or lumbar spine

• Importance of imaging entire spine

5

Common sites of injury in the elderly

• A.

  Osteoporosis

• Dowager’s hump

• Codfish vertebra deformity

• Acute fractures

• B.

  Pathologic fractures

• Differentiate from osteoporotic fractures

6

Fractures in the ankylosed spine

• Diffuse idiopathic skeletal hyperostosis (DISH)

• Ankylosing spondylitis

7

Common sites of injury in children and adolescents

• SCIWORA (spinal cord injury without radiographic abnormality)

• Anterior wedged compression fractures

• Flexion-distraction and Chance (seat-belt) fractures

• Apophyseal ring avulsions

8

Injuries likely to be missed

• Spinal radiographic examination obtained for significant trauma and not CT

  • CT is more sensitive than radiography in disclosure of fractures.

  • Radiographs fail to disclose 10% to 20% of fractures shown on CT.

• Second-level injury in multilevel spinal injuries

  • Must obtain CT of the remainder of spine once a significant spinal fracture is found

• Subtle widening of disc space in distraction or hyperextension injuries is overlooked.

  • Need to examine interspaces closely and compare with adjacent interspaces to avoid oversights

• Transverse process fractures

  • In most cases just failed to look specifically at transverse processes for fractures

  • Make it a point to examine transverse processes specifically in every case.

9

Where else to look when you see something obvious

10

Where to look when you see nothing at all

• If presented with radiographs of spine

  • Determine nature of injuring forces; if sustained significant injury, CT examination is required.

  • Re-evaluate radiographic examination looking for evidence of subtle fx.

  • If any question concerning above, obtain CT examination of spine.

• If presented with CT examination

  • If sustained neurologic injury, obtain MRI.

  • If no visible fracture or dislocation but has significant pain or inability to bear weight, obtain MRI.

  • Obtain MRI to disclose occult fx.

1

Imaging assessment

• Radiographic examination

  • AP

  • Lateral views

• Computed tomography (CT)

  • Axial

  • Reformatted images

    • Coronal

    • Sagittal

    • 3-D

Imaging techniques

In the setting of blunt trauma with suspected thoracolumbar spine injury, CT is recommended by the American College of Radiology (ACR) as part of the initial trauma workup in adults.

Clinical criteria that warrant thoracolumbar spine imaging include the following ¹ :

• Back pain or midline tenderness

• Local signs of thoracolumbar injury

• Abnormal neurological signs

• Cervical spine fracture or known cervical injury

• GCS <15

• Major distracting fracture

• ETOH/drug intoxication

• Rigid spine disease

In general, the thoracolumbar spine imaging with dedicated sagittal and coronal reformats of the spine can be provided from the CT chest, abdomen, and pelvis without need for additional dedicated spine CT imaging. In children <14 years CT of the thoracolumbar spine may be considered if there is a high clinical suspicion for injury, and either x-rays or CT may be indicated if a known cervical spine fracture is present. MR is clearly indicated for patients with neurologic abnormalities and may be required for evaluation of the discoligamentous complex.

Radiography

Radiography was long the mainstay of imaging the potentially injured spine but has now, in large measure, been replaced by CT. Still many radiographic examinations of the thoracolumbar spine are obtained in order to “clear” the spine in patients who are thought to have little chance of a spinal fracture, in the opinion of the examining physician on the basis of the patient’s history and physical examination. AP and lateral views of the thoracolumbar spine are sufficient for this purpose ( Fig. 7-1 ). However, if there is any question of an abnormality, a CT examination is required for proper evaluation.

The examples shown of normal AP and lateral radiographs of the thoracic and lumbar spines were obtained under ideal conditions on patients without a history of trauma. The spinal radiographs of those who have sustained significant trauma are often less satisfactory due to limitations of positioning and patient motion. The spine is much better seen on CT.

CT. Multidetector CT (MDCT) with routine, excellent, immediately available image reconstructions in both the coronal and sagittal planes is now the mainstay of imaging spinal trauma. CT has proven to be much more sensitive than radiography in the detection of spinal injuries; CT reveals fractures that are not apparent on radiographs and significantly more fractures in patients with fractures shown by radiography.

Thin section axial slices are obtained, and images are reconstructed in the coronal and sagittal planes. The thoracic and lumbar spine must be examined in its entirety. Once a significant fracture or dislocation of the spine has been identified, it is important to examine the remainder of the spine to exclude the presence of other spinal injuries. CT of the entire spine is performed to clear the spine in obtunded patients.