The anatomic definition of the thoracic spine includes the levels T1 to T12 and of the lumbar spine levels L1 to L5. Several authors have pointed out, however, that based on incidence and injury patterns, the thoracolumbar junction (T11 - L2) should be considered as a separate subgroup. The anatomic factors that distinguish the ‘thoracolumbar junction’ are as follows: (1) there is a sharp transition from the normal thoracic kyphosis to thoracolumbar lordosis; (2) the coronal orientation of the thoracic facets allowing rotation changes to the sagittal orientation of the lumbar facets allowing flexion/extension; (3) firmly attached ribs provide a buttressing support from T1 to T10; (4) in the thoracic region the spinal cord is contained within a relatively tight canal whereas the thoracolumbar junction conveys the conus medullaris and cauda equina in a capacious neural canal.

Most injuries caudal to the cervical spine occur at the thoracolumbar junction (T11 - L2). Specifically 50 per cent of all fractures occurring within the thoracic, lumbar, and sacral regions are located at the thoracolumbar junction. Injury to this region of the spine is most commonly caused by falls and motor vehicle accidents. Neurological damage in this region is less frequent and less ‘severe’ because of the increased canal volume and also the presence of the more resilient peripheral nervous system (nerve roots). In one group of patients there were 29 per cent complete neurological injuries, yet 27 per cent of patients were completely intact.

Initial management includes immobilization of the spine on a long fracture board and detailed neurological examination. Plain radiographs are usually supplemented by CT scans which serve to delineate the extent of vertebral column injury and also the amount of neural canal encroachment. Compromise of the thoracic canal that exceeds 50 per cent is associated with higher incidence of neurological injury and risk for progressive deficit.

Flexion loading of the thoracolumbar spine results in failure of the anterior column. The hallmark of this injury is a preserved middle column. The posterior column may sustain some degree of ligamentous injury or even bony avulsion in severe compression fractures. Initial evaluation of the plain radiographs should confirm an intact middle column as well as calculation of percentage anterior vertebral body height loss (Fig. 1) 2507. Axial tomography, although not always necessary, can better delineate posterior column injury and help in documenting the amount of vertebral body comminution. Neurological injury is rare and less severe in these injuries compared with burst fractures.

With sufficient axial load the anterior and middle columns may both fail. This results in a burst fracture with retropulsion of bony fragments into the neural canal. Typical findings on plain radiographs are fracture of the posterior wall of the vertebra with loss of posterior vertebral height. On the anteroposterior projection there is pathognomonic widening of the interpediculate distance and vertical laminar fractures. The amount of neural canal encroachment, the configuration of the retropulsed bone, and the status of the pedicles can best be assessed with CT scan.

The most hotly debated aspect of burst fractures has been the issue of treatment in the neurologically intact patient. Authorities arguing for conservative management cite satisfactory outcome despite kyphosis and no deterioration in neurological status. Furthermore, it has been suggested that fusion of uninjured levels may be deleterious to the overall function of the patient. The drawbacks of conservative management are a prolonged period of bed rest (up to 3 months in some series) and the complications of deep venous thrombosis, decubitus ulcers, and urinary tract infections which are reported to be as high as 30 per cent.

Surgical management may be accomplished with either anterior or posterior decompression. Patients with intact neurological function may be treated with posterior distraction instrumentation. Theoretically, the intact posterior longitudinal ligament, when placed under distraction with normal lordotic alignment achieved, aids in withdrawing the retropulsed fragments from the canal.

Recent development of modular segmental fixation utilizing pedicle screws has alleviated the necessity of long fusion in the treatment of single level burst fractures. The authors' experience has shown that instrumentation of the injured level and one level above and one below achieves very effective treatment of these injuries. In both intact and neurologically injured patients the early mobilization afforded by surgical stabilization has been a strong argument in favour of this approach.

If adequate and safe decompression cannot be carried out by a posterior approach then anterior surgery is indicated and completed with tricortical strut graft.

Also frequently described as the ‘seat-belt-type’ injury, this fracture results from a flexion force with the axis of rotation placed in front of the anterior column. This is a two-column injury with fracture through either purely bony or purely ligamentous (or a combination of bony and ligamentous) posterior and middle column elements. Radiographic findings in the true chance fracture include horizontal fracture through the transverse processes and pedicles extending for a variable distance through the vertebral body. Depending on the subtype of the fracture the spinous process may be fractured or an interspinous widening will be appreciated. Furthermore, the facets may be fractured or dislocated. With anterior column intact there is no translational component to this injury.

This category represents the most unstable injury patterns with failure of all three columns. The evaluating physician should bear in mind that the maximum displacement, which occurred at the time of injury, may have been corrected or reduced by the time initial radiographs are obtained. Hence, careful attention to radiographic findings will prevent dismissing these injuries as stable fractures. One should be particularly suspicious if multiple rib fractures, multiple transverse process fractures, or vertebral body offset are seen on the initial radiographs. The three subtypes of fracture - dislocations are the flexion - rotation, shear, and flexion - distraction injury.

The posterior and middle columns fail under tension and the anterior column may fail in rotation or compression and rotation. The pathognomonic radiographic finding is the dislocation of adjacent segments with variable amount of rotation.

The anterior column fails first at the level of the annulus from an extension load. The adjacent segments may be displaced in an anteroposterior or posteroanterior direction. In the former case the upper segment displaces forward on the lower segment and at the same time its neural arch is fractured free from the body. These injuries are easily recognized on lateral radiographs by the translation of involved segments.

This represents a continuation of the seat-belt-type injury with involvement of the anterior column. As described above, the elements that are fractured may be purely one level ligamentous or bony or a two-level combination of injuries. The distinguishing factor between these injuries and the Chance fracture, or its variants, is the complete disruption of the anterior column allowing displacement between the segments.

Treatment of fracture - dislocations first requires reduction of the malaligned spinal column. This goal may be accomplished with postural reduction alone. In cases where the facets have been dislocated or fractured, or when the adjacent segments are completely displaced and over-riding, open reduction may be required. The choice of approach needs to be tailored to the particular injury. Once reduction of the spine is achieved and the neural canal is decompressed the spine is stabilized internally. Preoperative planning must ascertain fractures at other contiguous or non-contiguous levels. Most of these injuries can be adequately stabilized with posterior instrumentation.

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