Thoraco Lumbar Spine Injuries Overview

Injuries to thoracic and lumbar spine have been mentioned in the history very frequently and date almost as back as 3000 BC. With increase in trauma following increasing in motor vehicles

Reports of trauma to the thoracolumbar spine with associated neurologic injury were described as early as 3000 BC in the Edwin Smith Papyrus. With the introduction of motorized vehicles and greater exposure to high-energy blunt trauma, the occurrence of thoracolumbar fractures and dislocations has increased substantially.

Recent studies suggest that motorcycle accidents are greatest culprits.

Thoracic and lumbar injuries  are responsible for 90% of all spinal injuries.

Distribution

Thoracolumbar injuries occur most frequently in male patients between 15 and 29 years of age. The distribution is similar to other types of spinal injuries.

Majority of thoracic and lumbar injuries occur within the region between T11 and L1, commonly referred to as the thoracolumbar junction.

Neurologic deficit reportedly occurs in approximately 15% to 20% of thoracolumbar fractures and dislocations.

Most of these injuries are caused by blunt trauma but gunshot wounds and osteoporosis have become more common.

Classification of Thoracolumbar Fractures Based On Mechanism  Of Injury

1. Pure Flexion

It causes a stable wedge compression fracture

2. Flexion and Rotation

It produces an unstable fracture-dislocation with rupture of the posterior ligament complex, separation of the spinous processes, a slice fracture near the upper border of the lower vertebra, and dislocation of the lower articular processes of the upper vertebra

3. Extension

It causes rupture of the intervertebral disc and the anterior longitudinal ligament and avulsion of a small bone fragment from the anterior border of the dislocated vertebra—this dislocation almost always reduces spontaneously and is stable in flexion

4. Vertebral Compression

which causes a fracture of the end plate as the nucleus of the intervertebral disc is forced into the intervertebral body, causing it to burst, with outward displacement of fragments of the body—because the ligaments remain intact, this comminuted fracture is stable

5. Shearing

It results in displacement of the whole vertebra and an unstable fracture of the articular processes or pedicles.

Denis later developed a concept of three columns

Anterior Column

is constituted by the anterior longitudinal ligament, the anterior half of the vertebral body, and the anterior portion of the anulus fibrosus.

Middle Column

It is formed by the posterior longitudinal ligament, the posterior half of the vertebral body, and the posterior aspect of the anulus fibrosus.

Posterior Column

It includes the neural arch, the ligamentum flavum, the facet capsules, and the interspinous ligaments.

Denis observed that one or more of these columns predictably failed in axial compression, axial distraction, or translation from combinations of forces in different planes.
Thus -

1. Wedge compression fractures cause isolated failure of the anterior column and result from forward flexion. They rarely are associated with neurological deficit except when multiple adjacent vertebral levels are affected.

2. Stable burst fractures result in  the anterior and middle columns fail because of a compressive load. However there is no loss of integrity of the posterior elements.

3. In unstable burst fractures, the anterior and middle columns fail in compression and the  posterior column can fail in compression, lateral flexion, or rotation.The posterior column is disrupted. There is a tendency for posttraumatic kyphosis and progressive neural symptoms because of instability.

If the anterior and middle columns fail in compression, the posterior column cannot fail in distraction.

4. Chance fractures are horizontal avulsion injuries of the vertebral bodies caused by flexion around an axis anterior to the anterior longitudinal ligament. The entire vertebra is pulled apart by a strong tensile force.

5. In flexion distraction injuries, the flexion axis is posterior to the anterior longitudinal ligament. The anterior column fails in compression, whereas the middle and posterior columns fail in tension. This injury is unstable because the ligamentum flavum, interspinous ligaments, and supraspinous ligaments usually are disrupted.

6. Translational injuries are characterized by malalignment of the neural canal, which has been totally disrupted. Usually all three columns have failed in shear. At the affected level, one part of the spinal canal has been displaced in the transverse plane.