PROCEDURE 47 Stabilization of Thoracic, Thoracolumbar, and Lumbar Fractures

• Osteoporosis (caution)

• Significant medical comorbities (caution)

• Life-threatening injuries (caution)

Controversies

• Kyphotic deformity greater than 30°

Treatment Options

• Basic principles for fracture management are (1) early decompression ± reduction, (2) stabilization, and (3) early mobilization.

• Surgical approaches are anterior, posterior, or combined approaches depending on the injury morphology, the integrity of the posterior ligamentous complex, and the patient’s neurologic status (intact vs. incomplete vs. complete).

Some fracture patterns maybe approached differently by different surgeons.

Significant lung injury may preclude an anterior thoracic approach.

The posterior approach technique and the anterolateral approach technique are discussed separately below.

• Methylprednisolone is a treatment option and is not mandatory for blunt spinal cord trauma in many spine centers. There are potential adverse events related to high-dose steroids, including higher incidence of early infections.

• Multimodal neuromonitoring during surgery maybe an option at some centers.

Examination/Imaging

Advanced Trauma Life Support protocols should be followed, including complete primary and secondary survey and ASIA assessment and detailed documentation of preoperative neurologic status.

Life-threatening injuries need stabilization.

Plain supine radiographs are obtained in anteroposterior (AP) and lateral views, including areas outside of the primary injury site to rule out noncontiguous fractures (can occur in 20% of patients with thoracolumbar and lumbar fractures).

Computed tomography (CT) scans with axial images and sagittal/coronal reconstructions are obtained for assessment of bony morphology and canal encroachment by bony fragments.

• CT visualizes the cervicothoracic region, which is difficult to assess with radiographs. CT scans also assess levels above and below the injury to see if there are additional fractures and to assess pedicle diameters/trajectories for screw insertion.

• In Case 1, preoperative axial (Fig. 1A) and sagittal (Fig. 1B) CT scans show disruption of the posterior ligamentous complex through the facet joint.

• In Case 2, a preoperative CT scan shows a burst fracture of L2 with retropulsion of the posterior vertebral body wall; however, the posterior ligamentous complex is intact (Fig. 2). This patient had symptomatic cauda equina compression.

• In Case 3, a preoperative CT scan showed a severe burst fracture with retropulsion of the posterior wall and disruption of the posterior ligamentous complex (Fig. 3).

Magnetic resonance imaging (MRI) is done in selected patients to assess the spinal cord for signal change and neural element compression by soft tissue structures such as traumatic disk herniations and epidural hematomas, and evidence of disruption of the posterior ligamentous complex.

• In Figure 4A, a sagittal CT reconstruction shows a thoracic fracture-dislocation with perched facets.

• A sagittal T₂-weighted MRI of the same patient (Fig. 4B) shows significant spinal cord edema and contusion at the level of the bony injury extending proximally. Clinically, this patient’s sensory level matched the bony injury level.

FIGURE 1

FIGURE 2

FIGURE 3

FIGURE 4

Surgical Anatomy

POSTERIOR APPROACH

Surgeons performing instrumentation should be familiar and comfortable with pedicle screw insertion landmarks, as well as pedicle screw trajectories and diameters, which vary from T1 down to S1.

• Figure 5 shows changing pedicle diameters in terms of transverse width (Fig. 5A) and sagittal width (Fig. 5B). In the thoracic spine, the transverse width of the pedicles is smaller than 9 mm, with the narrowest at T5. In the lumbar spine, the narrowest transverse width occurs at L1.

• Figure 6 shows the varying transverse angles of the pedicles from T1 to L5. In terms of transverse angles, the greatest amount of medialization occurs at T1 and L5, with angles of 27° and 30°, and the least occurs at the thoracolumbar junction at T12.

The spinal cord is at risk from medial pedicle screw breaches.

• Figure 7 shows a right-sided medial breach by a thoracic pedicle screw as seen on CT scan. Mild breaches such as this one have no impact on the patient’s clinical outcome. Inferior pedicle breaches can lead to nerve root injuries.

• Perforation of the anterior vertebral body may lead to vascular complications, including aortic perforation.

• Vascular perforations can present acutely or in a delayed fashion due to the pulsatile nature of the vessel next to a metal tip.

The thoracic spinal canal is narrowed, with decreased space for the cord, and there is a watershed zone for the blood supply. Both factors can lead to spinal cord injury with less canal intrusion than in other regions of the spinal column.

FIGURE 5

FIGURE 6

FIGURE 7

PITFALLS

• Heavier weighted individuals can develop complications related to prone positioning after prolonged surgery, such as meralgia paresthetica, despite adequate padding.

• Polytrauma patients can have multiple lines, such as endotracheal tubes, arterial lines, central lines, chest tubes, nasogastric tubes, and catheters, that need to be coordinated during a logroll or rotation with the Jackson table.

Positioning

POSTERIOR APPROACH

The posterior approach is done in the prone position.

A multiple-person logroll of the patient into the prone position is an option.

For incomplete spinal cord injuries with an unstable thoracic or thoracolumbar spine fracture, a Jackson table utilizing 360° rotation provides safer rotation into the prone position than manual logrolling with assistants (Fig. 8A).

For high thoracic fractures, Mayfield pins attached to the Jackson table (Fig. 8B), rather than a foam cushion or pad, can minimize external pressure on the eyeballs, which can be a factor in the development of blindness following spine surgery.