16 Thoracolumbar Fractures
Introduction
The transition zone at the thoracolumbar junction differs biomechanically from the stiff thoracic spine to the mobile lumbar spine. This zone of transition is related to the loss of the rib cage as well as the changing orientation of the facet joints. Because of these factors this area is prone to traumatic injury and accounts for approximately up to 50% of all vertebral body fractures and up to 40% of all spinal cord injuries. 1 , 2
Management of thoracolumbar fractures is a controversial topic in contemporary spine surgery. Early surgery for decompression and stabilization is generally accepted for patients with clear instability and an incomplete neurologic injury. Advantages of surgery include a better correction of deformity than closed reduction and bracing, an opportunity to perform direct or indirect decompression of the neural elements, decreased requirement for external immobilization, and fewer complications due to prolonged recumbency. The surgical treatment is more controversial for patients with mild to moderate deformity, without neurologic deficit, and residual spinal canal compromise, and the ideal solution remains largely unknown. 1 , 3 – 9
Classification
The most common fracture patterns at the thoracolumbar junction include compression fractures, burst fractures, flexion-distraction injuries, and fracture-dislocations.
Denis Classification
Compression Fractures
Failure of the anterior column in flexion/compression
A: Failure of the superior and inferior endplates
B: Superior vertebral endplate failure (most common type of compression fracture)
C: Inferior vertebral endplate failure
D: Failure of the central vertebral body with less involvement of the endplate
Burst Fractures
Compression failure of the anterior and middle spinal columns
A: Failure of both superior and inferior endplates
B: Superior endplate failure only (most common type of burst fracture)
C: Inferior endplate failure only
D: Axial loading and rotational injury
E: Axial loading and lateral flexion
Flexion-Distraction
(Chance): Primary anterior force vector acting along an axis of rotation located anterior to middle column. The posterior and middle columns fail in tension and the anterior column fails in tension or compression depending on the axis of rotation.
Fracture-Dislocation
Results from violent complex shearing force and by definition involves all three spinal columns. Highest rate of complete neurologic injury.
AO Thoracolumbar System (of Magerl)
Defines the major mechanism of spinal injury compression (A), distraction (B), and torsion (C) to indicate increasing injury severity occurring with increasing grade of injury. Three groups exist within each type (A1, A2, A3) and each group is divided into subgroups (A1.1, A1.2, A1.3). The classification is based on morphological criteria. The categories are established according to the main mechanism of injury, and take in to consideration the prognostic aspects of potential healing. The types are determined by the three most important mechanisms acting on the spine: compression, distraction, and axial torque. The type A is a vertebral body compression injury; type B injuries involve anterior and posterior element injuries with distractions; and type C lesions refer to anterior and posterior element injuries with rotation consistent with axial rotation injuries. The AO system is very comprehensive and good for describing fracture patterns, but it is a victim of its comprehensiveness; it does not consider neurologic status, and does not aid in decision making. 10
Thoracolumbar Injury Classification and Severity Score (TCLIS)
This system was developed due to the need for a classification system that could be used to prognosticate the need for surgical intervention. The system was based on a review of the existing literature as well as consensus opinion from a multinational group of leading spinal trauma surgeons. Three major injury characteristics were defined: injury morphology, neurologic status, and integrity of the posterior ligamentous complex (PLC) (see Table 16.1 ).
Injury characteristic | Qualifier | Points |
Injury morphology | ||
Compression | – | 1 |
Burst | +1 | |
Rotation/translation | – | 3 |
Distraction | – | 3 |
Distraction | – | 4 |
Neurologic status | ||
Intact | – | 0 |
Never Root | – | 2 |
Spinal cord, conus medullaris | Incomplete | 3 |
Complete | 2 | |
Cauda equine | – | 3 |
Posterior ligamentous complex integrity | ||
Intact | 0 | |
Suspected/indeterminate | 2 | |
Disrupted | 3 | |
+ = 1 additional point given to morphology | ||
Severity score: A score of > 4 suggests a need for surgical treatment because of significant instability, whereas a score < 4 suggests nonsurgical management. A patient with a score of 4 may be treated surgically or nonsurgically. 5 , 11 – 13
Indications
Grossly unstable injuries with or without neurologic deficit
To facilitate neurologic recovery via direct decompression or indirect decompression through ligamentotaxis
To correct deformity
To provide immediate stabilization
To decrease requirements for external immobilization, and complications due to prolonged immobilization
Preprocedure Considerations
Radiographic Imaging
Anteroposterior (AP) and lateral radiographs of the cervical, thoracic, and lumbar spine are standard imaging studies following spinal trauma. In some centers this has been largely replaced for survey purposes by whole body computed tomography (CT) scanning.
Because there is a high percentage of noncontiguous associated spinal fractures, entire neuraxis imaging may be warranted if clinical suspicion is high.
CT is generally the next step after plain films. Axial fine cuts and sagittal reconstruction help define fracture patterns and determine the degree of canal compression ( Fig. 16.1 ).
Magnetic resonance imaging (MRI): Generally not required in a neurologically intact patient in the acute setting, but can help evaluate the PLC. With a neurologic deficit, MRI is recommended to identify any ongoing spinal compression, evaluate cord anatomy, and rule out epidural hematoma.
Medication (Neuroprotection and Nonoperative Management)
According to the second NASCIS trial, in patients with confirmed spinal cord injury, patients started on methylprednisolone within 3 hours of injury had a substantial benefit in terms of ultimate neurologic recovery. We do not use steroids at our institution. Recent published guidelines do not recommend steroid usage. 14
Intravenous fluid, colloid, and vasopressors are used as needed to maintain a mean arterial pressure of 85 mm Hg or greater. 15
Surgical Management
The goals of surgical treatment include: (1) decompression of the spinal canal and nerve roots to facilitate neurologic recovery, (2) restoration and maintenance of vertebral body height and alignment to minimize posttraumatic deformity, (3) obtaining rigid fixation to facilitate nursing care and allow early mobilization, (4) obtaining a solid arthrodesis of damaged segments or fracture healing, and (5) limiting the number of instrumented vertebral motion segments. Surgical algorithms can generally be classified into one of five groups: (1) posterior decompression and stabilization, (2) costotransverse/lateral extracavitary/transpedicular decompression and reconstruction/stabilization, (3) anterior corpectomy/stabilization, (4) combined anterior/posterior decompression/stabilization (360), and (5) percutaneous fracture fixation.
Posterior approaches allow for realignment of the spine, direct and indirect decompression of the neural elements, and protection against late deformity and instability. Spinal canal decompression via ligamentotaxis is optionally achieved within the first 2 to 4 days post injury. We prefer to stabilize thoracolumbar fractures within 48 hours of presentation if medically stable. For thoracic injuries, a posterolateral, either costotransversectomy or transpedicular, approach allows some decompression of anterior pathology and allows a circumferential fusion through a posterior only approach.
This chapter addresses the posterior approach, both open and percutaneous.
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