Thoracic Spine Fractures and Dislocations Clinical Presentation

Updated: Oct 07, 2020
  • Author: Brian J Page, MD; Chief Editor: Murali Poduval, MBBS, MS, DNB  more...
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Presentation

Physical Examination

Upon initial presentation, an extensive physical examination should be performed and neurologic status documented. Concomitant injuries should be assessed. [1]  Hemothorax has been reported but is rare. [2] The patient's overall physical condition should be optimized promptly. Once the patient is stabilized hemodynamically and other visceral injuries have been investigated and excluded, definitive treatment of the thoracic spine injury can be contemplated. [3, 4, 5]

Several distinct classification schemes are available to assess spinal stability (see Classification below). [6]  

Next:

Classification

Fracture classification systems

Holdsworth initially proposed a model for assessing spinal stability that divided the vertebra into two columns as follows [7] :

  • Anterior column - Vertebral body, intervertebral disk, anterior longitudinal ligament (ALL), and posterior longitudinal ligament (PLL)
  • Posterior column - Facets, neural arch, and interspinous ligaments

Disruption of one or both columns implies instability of the involved segment.

Denis expanded on this model to develop the most common model used for assessing spinal stability, [8]  in which the vertebra is divided into three columns as follows:

  • Anterior column - Anterior two thirds of the vertebral body, ALL, anterior two thirds of the annulus fibrosus
  • Middle column - Posterior one third of the vertebral body, posterior one third of the annulus fibrosus, PLL
  • Posterior column - Posterior ligamentous complex and posterior bony elements

When two of the three columns are disrupted, the fracture may be unstable. [8]

Classification schemes generally also encompass mechanisms of injury and their resultant fracture patterns. Several different mechanisms of injury can occur within the thoracic spine. Most commonly, a combination of one or two mechanisms accounts for the injury. These mechanisms include the following:

  • Axial compression
  • Flexion
  • Lateral compression
  • Flexion-rotation
  • Shear
  • Flexion distraction
  • Extension

Axial compression results in a purely compressive load. Endplate failure occurs, followed by vertebral body compression. With higher energy, a centripetal displacement occurs, resulting in what is commonly referred to as a burst fracture (see the image below). In severe burst fractures, disks become fragmented and the posterior elements are disrupted. Radiographically, this mechanism can manifest as a widened interpedicular distance.

Thoracic spine fractures and dislocations. Burst f Thoracic spine fractures and dislocations. Burst fracture T12. Note the widened interpedicular distance.

Flexion results in compression anteriorly. Disruption of posterior elements with flexion often results in instability of the involved area. If anterior compression exceeds 40-50%, the posterior ligamentous structures are often disrupted. Instability ultimately can result in progressive deformity and neurologic deficit if not appropriately stabilized.

Lateral compression usually results in a stable injury unless disruption of posterior structures or associated axial compression occurs.

With a flexion-rotation injury, posterior ligamentous structures commonly fail. Oblique disruption of the anterior vertebral body and disk failure occur. This type of injury can result in what commonly is known as a slice fracture. With fractures of the facets and concomitant disruption of posterior elements, thoracic spine dislocation can occur.

Shear injuries often result in severe ligamentous disruption and subsequent anterior, posterior, or lateral listhesis. Anterolisthesis is the most common of the three, with complete spinal cord injury (SCI) often being the unfortunate result. However, occasionally, concomitant fractures through the pars interarticularis result in autolaminectomy, with resultant neural sparing.

Flexion distraction injury (see the image below) is more commonly referred to as the seatbelt injury. The axis of flexion is anterior to the vertebral column. Osseous, disk, and ligamentous structures are disrupted, either alone or in combination. Combined osteoligamentous or purely ligamentous injuries can be present, and this injury occurs most commonly at the thoracolumbar junction. Bilateral facet dislocation can occur.

Thoracic spine fractures and dislocations. Flexion Thoracic spine fractures and dislocations. Flexion distraction injury with facet dislocation.

Extension places tension on the anterior longitudinal ligament, with compression occurring posteriorly. Facet, laminar, and spinous process fractures often occur. Most of these injuries are stable, provided that significant retrolisthesis does not occur.

In the Denis classification system, significant fractures are divided into the following three groups:

  • Primarily axial load injuries, including compression and burst fractures
  • Flexion-distraction injuries
  • Fracture subluxation and/or dislocation (see the image below)
Thoracic spine fractures and dislocations. Fractur Thoracic spine fractures and dislocations. Fracture dislocation T2-T3.

The mechanism of failure of the middle column further differentiates the various types of fractures. The middle column is spared in compression fractures, yielding a stable fracture. It fails in compression with burst fractures, distraction in seatbelt injuries, and shear and/or rotation injuries. Fracture dislocations yield unstable injuries.

The Denis classification system has been criticized on the basis of its occasional inability to be provide an adequate distinction between stable and unstable fractures—for example, the "stable" burst fracture. In addition, biomechanical studies have brought into question the importance of the middle column. Recognizing this issue, McAfee expanded on the Denis classification scheme to further elucidate the distinction between stable and unstable fractures. His classification system emphasized the posterior ligamentous complex as a major factor in fracture stability.

Another shortcoming of structural or mechanistic classifications is that they often fail to take neurologic deficit into account. Significant neurologic injury implies instability irrespective of the fracture pattern, in that the spine has clearly failed to protect the neural elements.

Complete vs incomplete spinal cord injuries

Neurologic deficits in these injuries can range from normal neurologic function to complete SCI. [9]  Complete SCI is defined as a complete loss of motor and sensory function below the level of the injury in question, whereas with an incomplete injury, there is some level of residual motor or sensory function below the level of the injury.

SCIs are typically classified according to the American Spinal Injury Association (ASIA) classification, which is a grading system used to help quantify the degree of neurologic impairment in patients with acute spinal trauma. The ASIA classifications includes the following five grades of SCI:

  • ASIA A – Complete loss of motor and sensory function
  • ASIA B – Complete loss of motor function with intact or partially intact sensory function
  • ASIA C – Motor function preserved below the neurologic level, with more than half of the muscles below having a muscle grade less than 3
  • ASIA D – Motor function preserved below the neurologic level, with at least half of the muscles having a muscle grade of 3 or higher
  • ASIA E – Normal

Definitive classification of complete SCIs can only be done in a patient who is not in spinal shock. [10]  Spinal shock is defined as a state of flaccid paralysis from disturbance of spinal cord function below the level of an SCI. This state typically lasts for approximately 48 hours, and its conclusion is defined as return of the bulbocavernosus reflex.

As mentioned earlier, complete SCIs are those in which motor and sensory function are completely absent, whereas incomplete injuries are those in which some level of motor or sensory function remains. There are a few classic patterns in which incomplete SCIs present, as follows.

Central cord syndrome

Central cord syndrome, the most common incomplete SCI, typically results from a hyperextension injury to the cervical spine in a patient with a stenotic spinal canal.

The injury occurs in the center of the spinal cord, damaging the lateral corticospinal tract. Because it is a more centrally based injury, it damages the axonal tract supplying the upper extremity (which is more central) before damaging the axonal tract supplying the lower extremity. Therefore, individuals with this type of injury typically present with more upper-extremity neurologic dysfunction than lower-extremity dysfunction.

The overall prognosis is good, especially in younger patients, with regard to the ability to ambulate. However, patients may have permanent upper-extremity dysfunction. [11]

Brown-Sequard syndrome

Patients with Brown-Sequard syndrome, which is typically seen in the setting of penetrating trauma, exhibit impaired ipsilateral motor function with contralateral pain and temperature sensation dysfunction below the level of injury. Anatomically, this type of injury is due to the decussation of motor fibers occurring within the brainstem, while pain and temperature fibers decussate within the spinal cord itself in the spinothalamic tracts innervating the second level below the region in which the fibers cross.

Of patients with incomplete SCIs, these individuals typically have the best prognosis, more specifically with regard to motor functional outcomes. [12]

Anterior cord syndrome

Anterior cord syndrome results from injury to the anterior two thirds of the spinal cord, which includes the corticospinal and the spinothalamic tracts. These two tracts contain nerve fibers that deal with motor function and with pain and temperature function, respectively. The mechanism of injury is typically direct compression from thoracic spine fractures or injury to the anterior spinal artery. Patients typically have motor dysfunction below the injury level with preserved deep pressure and proprioception.

The prognosis for these injuries is poor. [13]

Posterior cord syndrome

Posterior cord syndrome, the least common incomplete SCI, involves injury to the posterior columns of the spinal cord. It typically results from a posteriorly based injury (eg, impact from a lamina fracture). [13]

Thoracolumbar Injury Classification and Severity Score

Several classification systems have been devised for the evaluation of thoracolumbar trauma; however, the most commonly used scheme is the Thoracolumbar Injury Classification and Severity (TLICS) score (also sometimes known as the Thoracolumbar Injury Severity Score [TISS]). The TLICS was developed with the goals of improving the care of patients with these injuries and providing a system that could be applied to everyday practice. It has subsequently been shown to be valid and clinically useful for determining the final treatment of these injuries.

Briefly, the TLICS takes three injury characteristics—injury morphology, neurologic status, and posterior ligamentous complex integrity—and assigns points to each characteristic on the basis of severity. These points are summed to yield a total score, which is then used to guide treatment. An injury with a score higher than 4 is typically managed surgically; an injury with a score lower than 4 is typically managed without surgery; and an injury with a score of 4 may be managed with or without surgery, at the discretion of the surgeon. [14, 15]

AO/OTA classification

In 2018, the AO Foundation and the Orthopaedic Trauma Association (OTA) issued an updated classification of thoracolumbar spine injuries. [16] ​ The three main types are as follows:

  • A - Compression injury of the vertebral body
  • B - Tension band injury
  • C - Displacement/translational injury

Type A injuries are subclassified as follows:

  • A0 - Minor nonstructural fractures (eg, spinous or transverse processes)
  • A1 - Compression or impaction fractures of a single endplate without involvement of the posterior wall of the vertebral body
  • A2 - Coronal split of pincer-type fractures involving both endplates without involvement of the posterior vertebral wall
  • A3 - Incomplete burst fracture involving a single endplate with any involvement of the posterior vertebral wall
  • A4 - Complete burst fracture involving both endplates as well as the posterior wall

Type B injuries are subclassified as follows:

  • B1 - Monosegmental osseous failure of the posterior tension band extending into the vertebral body (Chance fracture) 
  • B2 - Disruption of the posterior tension band with or without osseous involvement; posterior tension band injury may be bone, capsule, ligament, or a combination
  • B3 - Anterior tension band injury with disruption or separation of the anterior bone and/or disk with tethering of the posterior elements

Type C injury involves failure of all elements leading to dislocation, displacement, or translation in any plane or complete disruption of a soft-tissue hinge even in the absence of any translation. It can be combined with subtype A or B, allowing for two separate codes for an injury.

In addition, the following six neurologic grades are specified and are added to any spinal code to identify the neurologic deficit:

  • NX - Cannot be examined
  • N0 - Neurologically intact
  • N1 - Transient neurologic deficit 
  • N2 - Nerve root injury
  • N3 - Cauda equina injury or incomplete spinal cord injury  
  • N4 - Complete spinal cord injury
  • + Indicates there is ongoing cord compression in the setting of an incomplete neurologic deficit
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