Pathophysiological Features of the Subtypes of Thoracolumbar Spine Trauma in Children

Compression fracture

• Most common fracture pattern: Compression fracture is the most common fracture pattern in pediatric spine.
• Causes: This injury results from axial loading and flexion forces. Children are susceptible to this type of injury because of wedge shape of vertebral bodies and natural kyphosis. The fracture results from anterior collapse of the vertebral bodies (anterior column), which causes anterior vertebral body loss of height.
• Low-energy mechanisms: It is generally seen in low-energy mechanisms, such as falls and sports injuries.
• Loss of height: With over 50% loss of height, consideration should be given to posterior element disruption and obtaining an MRI is suggested (26). In skeletally immature children, restoration of fracture height loss can be seen over time.
• Location near thoracolumbar junction: Compression fractures most commonly occur near the thoracolumbar junction, and they can be can be multiple contiguous levels.
• Rare deficit:Neurologic deficit is rare in this pattern of fracture.

Burst fracture

• Causes: This injury results from axial loading forces.
• Results: This fracture causes collapse of the anterior and middle column, resulting in loss of height and possible retropulsion of bone into spinal canal. Retropulsion of bone into the spinal canal and fracture of the posterior elements can lead to instability, neurologic injury, and dural tears.
• High-energy mechanisms: It is generally seen in high-energy injuries.
• Location near thoracolumbar junction: Burst fractures most commonly occur near the thoracolumbar junction.
• Risk of neurologic deficit: Thoracic fractures are more likely to cause neurologic injuries.
• Imaging modalities: CT is utilized to evaluate the amount of retropulsion, canal compromise, and osseous fractures. MRI is useful to visualize neurologic structures, integrity of posterior ligamentous complex, and epidural hematoma.

Flexion-distraction (Chance fracture, seat belt injury)

• Results in three-column fractures: This injury results in three-column fractures (anterior, middle, posterior). The injury can be purely osseous, purely ligamentous/disc, or a combination.
• Causes: It is caused by distractive forces, with flexion and failure of posterior or anterior column.
• Concurrent injuries: Concomitant abdominal or head injuries are commonly seen (~40%) (28). A “seat belt sign” (bruising on the skin) can be often noticed across the abdomen.
• Frequent neurologic injury: Many patients can have concomitant neurologic injury with this pattern of injury (~40%).(29)
• Imaging modalities: CT is used to evaluate the extent and pattern of osseous fractures. MRI is useful to visualize neurologic structures, integrity of posterior ligamentous complex, and epidural hematoma.

Fracture-dislocation

• Causes: This injury is caused by high-energy torsional, distraction, or shearing forces.
• Uncommon: It is an uncommon injury pattern.
• Concomitant neurologic injury is common: Fracture-dislocation is commonly associated with neurologic deficits.
• Unstable: This fracture pattern is unstable.

Apophyseal fracture and herniation

• Most common in 10- to 14-year-old children: The injuries generally occur in children between 10 and 14 years of age (7).
• Causes: It is the result of separation of the vertebral apophysis from the vertebral body, causing herniation into the spinal canal (7).
• Location at L4 or L5: The most common levels injured with this pattern are L4 or L5.
• Imaging modalities: MRI is recommended to evaluate presence, location, and size of herniation.
• Concurrent injuries: It can present with back pain, radicular pain, lower extremity weakness, or cauda equina symptoms (7).

Spinous process/transvers process fracture

• Causes: These fractures are caused by blunt trauma.
• Stable: They are stable injuries.

SCIWORA

• Most common in children under 8: It is more commonly seen in children under 8 years old.
• Causes: This is caused by a high-energy injury. SCIWORA occurs because of hypermobility of spine and lack of tolerance of the spinal cord to handle stretch.
• Cervical spine location: It is seen more frequently in the cervical spine, compared to thoracic spine (13% of SCIWORA cases) (6).
• Imaging modalities: No fractures or dislocations seen on x-rays or CT. MRI is useful to evaluate patients with neurologic deficits without osseous injury.
• Risk of neurologic injury: It can be complete or partial neurologic injury.