# Thoracolumbar Fractures: Classification and Stabilization

## Introduction

Thoracolumbar fractures are the most common spinal fractures, with approximately 90% occurring between T11 and L2, the thoracolumbar junction. This region is biomechanically vulnerable because it represents the transition from the rigid, kyphotic thoracic spine (stabilized by the rib cage) to the mobile, lordotic lumbar spine. Appropriate classification and management decisions are critical to prevent neurological deterioration and chronic pain.

## Anatomy and Biomechanics

The thoracolumbar junction (T10 to L2) is the most common site of injury. The Denis three-column model divides the spine into the anterior column (anterior longitudinal ligament, anterior half of the vertebral body and disc), the middle column (posterior half of the vertebral body, posterior longitudinal ligament), and the posterior column (pedicles, facet joints, laminae, spinous processes, ligamentum flavum, interspinous and supraspinous ligaments). The spinal cord terminates at the conus medullaris (L1 to L2), so injuries below this level affect the cauda equina. The thoracic spine is stabilized by the rib cage and costovertebral articulations, which reduce fracture risk in that region.

## Classification Systems

### AO Spine Thoracolumbar Classification

Type A fractures are compression injuries from axial load, ranging from A0 (minor, non-structural) through A1 (wedge compression of a single endplate), A2 (split involving both endplates), A3 (incomplete burst with single endplate and posterior wall involvement), and A4 (complete burst with both endplates and posterior wall involvement). Type B fractures are distraction injuries: B1 is a transosseous posterior tension band injury (Chance fracture), B2 is a posterior ligamentous tension band failure (flexion-distraction), and B3 is an anterior tension band injury (hyperextension). Type C fractures involve translation or rotation in any plane and are highly unstable.

### Thoracolumbar Injury Classification and Severity Score (TLICS)

| TLICS Component | Options | Points |
|-----------------|---------|--------|
| **Morphology** | Compression | 1 |
| | Burst | 2 |
| | Translation/rotation | 3 |
| | Distraction | 4 |
| **PLC Integrity** | Intact | 0 |
| | Suspected/indeterminate | 2 |
| | Injured | 3 |
| **Neurological Status** | Intact | 0 |
| | Nerve root injury | 2 |
| | Incomplete cord/conus | 3 |
| | Complete cord injury | 2 |
| | Cauda equina | 3 |
| **Treatment** | Score < 4: Nonoperative | |
| | Score = 4: Surgeon discretion | |
| | Score > 4: Operative | |

The TLICS is a scoring system that guides operative decision-making. Morphology is scored as compression (1 point), burst (2), translation or rotation (3), or distraction (4). Posterior ligamentous complex (PLC) integrity is scored as intact (0), suspected or indeterminate (2), or injured (3). Neurological status is scored as intact (0), nerve root injury (2), incomplete cord or conus (3), complete cord injury (2), or cauda equina (3). A total TLICS below 4 favors nonoperative management, a score of 4 is at the surgeon's discretion, and a score above 4 recommends operative management.

## Clinical Evaluation

The ATLS protocol guides the primary survey and hemodynamic stabilization. A thorough neurological examination assesses motor function, sensory levels, rectal tone, and the bulbocavernosus reflex. The ASIA Impairment Scale (A through E) classifies the level of neurological injury. Physical examination assesses thoracolumbar kyphosis, step-off, interspinous widening, and paraspinal tenderness. Associated injuries should be evaluated, including calcaneus fractures from axial loading, other spine levels, and intra-abdominal injuries.

## Imaging

CT is the primary imaging modality for assessing fracture morphology, canal compromise, and posterior element involvement. MRI is essential for evaluating PLC integrity (disruption of supraspinous and interspinous ligaments and ligamentum flavum), spinal cord or cauda equina compression, disc herniation, and epidural hematoma. STIR sequences on MRI are particularly useful for detecting ligamentous injury and marrow edema. Standing radiographs assess alignment and sagittal balance and are used for serial imaging during nonoperative management.

## Nonoperative Management

Nonoperative treatment is indicated for TLICS below 4: stable compression fractures with an intact PLC in neurologically intact patients. A TLSO (thoracolumbosacral orthosis) or Jewett brace is worn for 8 to 12 weeks. Serial upright radiographs monitor for progressive kyphosis, with more than 10 degrees of progression warranting reconsideration of the management strategy. Early mobilization and physical therapy are encouraged, along with multimodal analgesia for pain management. For osteoporotic compression fractures, vertebral augmentation (kyphoplasty or vertebroplasty) is considered for refractory pain after 3 to 6 weeks of conservative care.

## Operative Management

### Posterior Instrumentation and Fusion

Pedicle screw fixation is the standard technique, providing three-column stabilization. Short-segment fixation (one level above and below) with or without fracture-level screws is used for most cases. Long-segment fixation is reserved for highly comminuted fractures, osteoporotic bone, or translation injuries. Fracture-level pedicle screws (short-segment plus intermediate screws) reduce hardware failure and loss of correction. Posterior decompression with laminectomy is performed if there is posterior canal compromise.

### Anterior Approaches

Anterior approaches are indicated for significant anterior column comminution, anterior canal compromise, or failed posterior surgery. Corpectomy with structural graft (cage, autograft, or allograft) and anterior plate or rod fixation is performed. The thoracolumbar junction is approached via a thoracoabdominal or retroperitoneal approach.

### Combined Anterior-Posterior

Combined approaches are used for highly unstable injuries (Type C) and three-column injuries with severe comminution. Procedures may be staged or performed on the same day depending on patient stability.

### Minimally Invasive Surgery (MIS)

Percutaneous pedicle screw fixation reduces tissue damage and blood loss. It is appropriate for burst fractures without severe canal compromise, and growing evidence supports equivalent outcomes with reduced morbidity.

## Special Fracture Patterns

### Chance Fracture (Flexion-Distraction)

The Chance fracture is a horizontal fracture through the vertebral body, pedicles, and posterior elements. It is associated with seat-belt injuries and intra-abdominal injuries in 40 to 50% of cases. Bony Chance fractures may heal with bracing, while ligamentous injuries typically require posterior fusion.

### Burst Fractures

Burst fractures result from axial load failure of the anterior and middle columns with retropulsed fragments into the canal. Canal compromise does not necessarily correlate with neurological deficit. Neurologically intact patients with an intact PLC and less than 30 degrees of kyphosis may be managed nonoperatively.

## Clinical Pearls

The TLICS score provides an evidence-based framework for operative decision-making: below 4 is nonoperative, above 4 is operative. PLC integrity is the single most important factor in determining stability, and MRI is the best modality for its assessment. Chance fractures are strongly associated with intra-abdominal injuries that require evaluation. Short-segment pedicle screw fixation with fracture-level screws reduces hardware failure rates. Serial imaging is mandatory in nonoperatively managed fractures to detect progressive kyphotic deformity.

## References
1. Vaccaro AR, Lehman RA Jr, Hurlbert RJ, et al. "A New Classification of Thoracolumbar Injuries: The Importance of Injury Morphology, the Integrity of the Posterior Ligamentous Complex, and Neurologic Status." *Spine*. 2005;30(20):2325-2333.
2. Kepler CK, Vaccaro AR, Schroeder GD, et al. "The Thoracolumbar AOSpine Injury Score." *Global Spine Journal*. 2016;6(4):329-334.
3. Wood KB, Li W, Lebl DR, Ploumis A. "Management of Thoracolumbar Spine Fractures." *Spine Journal*. 2014;14(1):145-164.
4. Reinhold M, Knop C, Beisse R, et al. "Operative Treatment of 733 Patients with Acute Thoracolumbar Spinal Injuries." *European Spine Journal*. 2010;19(10):1657-1676.