Operative Treatment of Thoracolumbar Burst Fractures

Indications/Considerations

Goals for operative treatment of thoracolumbar burst fractures include adequate decompression and fracture stabilization.
- Direct or indirect decompression is necessary to manage incomplete or root-level neurologic deficit.
- Stabilization without fusion and subsequent removal of instrumentation may be considered if adequate indirect decompression is obtained through fracture reduction and reliable healing is expected.
  - Resorption of retropulsed fragments has been demonstrated.
- Fusion is necessary if anterior decompression via corpectomy is performed.
A posterior-only approach allows for single-stage decompression and instrumentation, without the additional operative time, blood loss, and physiologic burden of an anterior approach.
A combined anterior-posterior approach allows direct decompression by way of a corpectomy, with reduction and stabilization through the anterior column using a cage or allograft strut.
- Posterior reduction and stabilization can be performed first to achieve indirect decompression, followed by an immediate or delayed anterior approach depending on the patient’s status.
- Anterior decompression and stabilization can be performed first if there is significant canal compression with fragments not safely reducible via a posterior approach or there is marked kyphotic deformity.
- An anterior-only approach may be considered if the posterior tension band is intact.
Percutaneous pedicle screw instrumentation achieves deformity reduction, indirect decompression, and stabilization while limiting approach-related morbidity.
- Indications continue to be established; these include
  - Unstable thoracolumbar burst fractures
  - Stable fractures with failure of conservative management
  - Loss of the posterior tension band or progressive kyphosis without severe stenosis
- No preoperative criteria reliably predict adequacy of indirect decompression and therefore may be assessed intraoperatively.
Posterior, combined anterior-posterior, and percutaneous methods will be discussed separately.
Indications for each approach are relative and are determined individually by case (Table 34-1).

Radiologic Assessment

CT is mandatory in the evaluation of thoracolumbar burst fractures to identify:

Additional injuries
Fracture comminution

Involvement of the posterior elements

Table 34-1 Considerations for Anterior Versus Posterior Approaches

Anterior	Posterior
*Pros*
Direct decompression of bony stenosis because of fracture fragments from the anterior column Height restoration of the anterior column Reconstruction of the anterior column Stabilization with inadequate posterior fixation	Combined indirect decompression, reduction, and stabilization with pedicle screw constructs Limited approach morbidity with percutaneous instrumentation Allows subsequent anterior or lateral approaches if necessary for decompression or supplemental fixation
*Cons*
Extensive and morbid approach Lack of familiarity or approach; surgeon availability Possible thoracotomy pain, intra-abdominal or pulmonary complications	Direct decompression, particularly in the thoracic spine, may be difficult The extent of reduction without direct manipulation of the anterior column may be limited

Bony retropulsion
Relative feasibility of adequate indirect decompression

Upright thoracolumbar x-rays may be used to evaluate:
- Overall spinal alignment and the degree of focal kyphosis with loading
- Approximate bone quality; osteopenia is often severe before it can be noticed on standard radiography and may also be evaluated by CT.
MRI is useful to evaluate:
- The degree and location of neural element compression
- The presence of epidural hematoma or durotomy with pseudomeningocele formation
- Injury to the posterior longitudinal ligament or the posterior ligamentous complex
An isolated vertical fracture of the lamina is not specific for tension band failure.
Pedicle anatomy must be assessed prior to instrumentation.
Assess regional vascular anatomy, particularly if contemplating a corpectomy.

Open Posterior-Only Treatment of Thoracolumbar Burst Fractures

A 50-year-old female presented with back pain, lower extremity weakness, decreased sensation, and difficulty voiding following a motor vehicle accident (Figures 34-1, 34-2, 34-3).

Figure 34-1 ▪ A, B, Preoperative anteroposterior and lateral x-rays demonstrate an L1 burst fracture associated with involvement of the anterior and middle columns and vertebral height loss. The interpedicular distance is widened and there is focal kyphosis. The posterior vertebral line is disrupted, indicating retropulsion.

Figure 34-2 ▪ A, B, Preoperative sagittal and axial CT reconstructions demonstrate again the L1 burst fracture with retropulsion of large fragments including one fragment rotated and displaced into the spinal canal. Local kyphosis, vertebral height loss, and fracture comminution are present. Additional injuries, involvement of the posterior elements, pedicle anatomy, and the feasibility of indirect decompression may be assessed.

Figure 34-3 ▪ A-C, Preoperative sagittal and axial T2 MRI further define the L1 burst fracture with severe canal stenosis involving the conus medullaris, presence of epidural hematoma, and intact posterior elements. Local soft tissue anatomy and vasculature may be evaluated.

Positioning

The patient is carefully logrolled into the prone position on a radiolucent Jackson spine frame.
Proper positioning may assist in fracture reduction and creation of lordosis with use of chest pads and careful placement of the hip pads with hip extension.
Reverse Trendelenburg reduces blood loss in the hyperemic traumatized zone of injury.

Anesthesia and Neuromonitoring Concerns

Neuromonitoring with somatosensory evoked potential (SSEPs) and transcranial motor evoked potential (TcMEPs) with total intravenous anesthesia allows recognition of change in spinal cord function with minimal deterioration in signals associated with prolonged anesthesia.
If concurrent cervical spine injury was identified on trauma examination or imaging, extreme caution is used during intubation, avoiding neck hyperextension.
Tranexamic acid may be used to limit blood loss and improve outcomes in some polytraumatized patients.

Localization of Incision

Local edema and disruption of surrounding body anatomy because of trauma may limit identification of local landmarks, necessitating localization prior to incision.
Localization by plain film or fluoroscopy with needles (as described elsewhere in this book) at the extents of the proposed surgical site should be obtained. The fractured vertebra may be used as a landmark. Anteroposterior (AP) or lateral imaging may be used in the thoracic spine given overlapping bony anatomy.

Approach and Retractor Placement

A standard posterior thoracic approach is taken as described elsewhere in this book.

Decompression and Instrumentation Techniques

After completion of the posterior approach, pedicle screws are placed; facet capsules are preserved if fusion is not planned.
- Multisegmental instrumentation may be considered in the thoracic spine as loss of segmental motion is better tolerated.
- Fixed screws improve reduction force.
  - Reduction is perpendicular to the rod, and therefore screw position is critical.
  - Reduction forces may cause pullout in osteopenic bone.
- Intermediate pedicle screws at the injured vertebral body provide greater biomechanical stability if pedicles are intact.
  - Screw lengths are kept short of fracture comminution so that fixation is obtained at and just anterior to the pedicle.
  - Anterior reconstruction remains possible if required.
  - Screw heads may be left proud to further improve reduction and indirect decompression with rod placement.
- Schanz pins may be used in the lumbar spine to achieve fracture reduction and lordosis.
  - C-washers transfer construct rotation to the rod.
  - Use of pins limits multisegmental stabilization.
Distraction is applied to provide initial fracture fragment reduction that will facilitate direct posterolateral decompression; care must be taken to limit iatrogenic kyphosis because of distraction.
A rod is secured contralateral to the side chosen for decompression.
- A kyphotic rod is used for fractures from T1 to T10, straight or slightly lordotic from T11 to L2, and lordotic for lumbar fractures.
- The ipsilateral rod is removed to aid exposure and decompression.
- Rod length is based on the expected final construct following distraction.
The spinous process, lamina, facet, and pars interarticularis are removed.
The pedicle is isolated and a burr is used to widen the pedicle and enter the vertebral body.
Reverse angled curettes are used to impact cancellous bone into the vertebral body, forming a recessed pocket that will allow reduction of the retropulsed cortical fragments.
After the recess is created, a long-footed impactor is used to tamp the retropulsed fragment into the recess, clearing the spinal canal.
- Fragments are commonly located at the junction of the disk and the superior endplate.
- Annular attachments to the fracture fragments and interposing disk material may prevent fragment reduction; partial excision of the disk and attached fracture fragments will allow adequate decompression.
Associated vertical lamina fractures may be associated with traumatic durotomy, which may be repaired or patched.
Adequacy of decompression is assessed and, when completed, the ipsilateral rod is placed and secured.
Cross-links improve biomechanical torsional stability, which is best achieved with a short working length from the site of fracture.
If indicated, a posterolateral fusion is then performed using bone graft material of choice, as detailed elsewhere in this book.
- Graft may also be placed at the body via the transpedicular approach.
Prior to wound closure, AP and lateral intraoperative imaging must confirm adequacy of reduction, implant position, and coronal and sagittal alignment (Figure 34-4).

Figure 34-4 ▪ A, B, Postoperative anteroposterior and lateral x-rays demonstrate reduction, decompression, and stabilization of the fracture with well-positioned multisegmental instrumentation from T11 to L3. The rod contour allows for proper sagittal and coronal alignment across the thoracolumbar junction. The use of cross-links with short working length improves biomechanical stability to torsion.

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