Learn whether a common T-L compression fracture warrants further consideration of a pathologic process

Fractures of the thoracolumbar spine are injuries that occur frequently—simple compression fractures affect 8.4% of males and 26.7% of females by age 85.¹ The simple compression fracture constitutes the most common type of fracture, accounting for approximately 66% of fractures sustained in this region.²

Compression fractures of the thoracolumbar spine are typically a result of axial loading, for example following a violent sneeze. The upper thoracic spine is an unusual site for a compression fracture to occur and should warrant the consideration of a pathologic process leading to the fracture in the absence of a history of trauma.

Compression fractures of the spine often lead to the development of clinical symptoms. The typical presentation of an acute compression fracture is that of a postmenopausal woman (or older man) who develops sudden pain and deformity in the thoracic spine. However, symptoms related to the development of compression fractures may be strikingly absent—present in only about one third of patients.

Radiographic evidence of a new or recent compression fracture include the presence of a zone of condensation, a step defect, and soft-tissue swelling (only detectable in the thoracic spine). In addition, evidence of previous spinal compressive injuries may be evident in the case of an ostepenic patient.

The zone of condensation represents a region of bone where telescoping of the trabeculae has occurred as a result of the axial/compression injury (green arrows), a sign of a new/recent compression fracture. The step defect is also a sign of a recent compression fracture and is due to the movement anteriorly of the superior plateau during the compression injury.

Paraspinal soft-tissue swelling may be present in a new compression fracture, and may be seen only in the thoracic spine due to the attenuation of the soft-tissue swelling surrounding the pulmonary parenchyma.

In a healed compression fracture, residual deformity of the vertebral body may be apparent as well as early degenerative disc disease of the segments surrounding the site of injury.

The posterior body wall is a vital area to assess in a patient with evidence of a compression fracture. The alignment of the posterior body wall should be evaluated with comparisons with the level above and below, using the posterior body line (George’s line). The line should be smooth and uninterrupted. If interruption of this smooth continuous line is noted at the level of the compression fracture, the likelihood of a burst-type fracture with posterior extension is increased, and computed tomography (CT) is required to assess the integrity of the central spinal canal.

The height of the posterior body wall must also be assessed with respect to the levels above and below. The height of the posterior body wall should be within 2 mm of the height of the level above and below. If evidence of loss of the posterior body height is present, the possibility of a pathological fracture should be considered. Causes of a pathological compression fracture include osteolytic metastatic disease and multiple myeloma.

Case History
In case 1 (Figures 1A and 1B) , sudden pain in the middle of the back was sustained following a motor vehicle accident. There were no neurological symptoms or signs.

For case 2 (Figures 2A and 2B), the sudden pain in the middle of the back was felt following a fall from a first-story window. Again, there were no neurological symptoms or signs.

In Figures 1A and 1B, a lateral conventional tomograph of the thoracolumbar region with increased density of bone is noted just below the level of the superior plateau of L1 (green arrow)—a zone of condensation. A defect of bone is also noted extending anteriorly from the anterior superior plateau of L1 (white arrow).

Figure 2A and 2B Conventional radiograph of the TL region: In case 2, there is a focal loss of the anterior height of the vertebral body of L1. There is a disruption of the posterior body line (George’s line) with posterior extension of the L1 vertebral body limits (white vertical line).

In Figures 2A and 2B, a conventional radiograph of the thoracolumbar region demonstrates a focal loss of the anterior height of the vertebral body of L1. However, in this case there is disruption of the posterior body line (George’s line), with posterior extension of the L1 vertebral body limits (white vertical line). A region of bony condensation is present in the subchondral region of the vertebral body, a zone of condensation, or zone of sclerosis (green arrow). A defect in the anterior superior end-plate of L1 is outlined by the white arrow, a step defect.

Figure 1 represents a conventional tomogram of a simple compression fracture. However additional slices are needed to assess the full extent of this fracture.

Figure 2 represents a burst fracture, which has extended to involve a portion of the central spinal canal.

In both cases, further imaging using CT is necessary to establish the full nature of the injuries sustained with particular regard for the integrity of the central spinal canal allowing for the essential differentiation of a simple compression fracture (where George’s line is respected) from a complex/burst type fracture which requires an orthopedic/neurosurgical consulation (where a breach of George’s line is evident). CP

Michelle Wessely, BSc (Chiropractic), DC, DACBR, FCC (UK/Radiology), is the departmental head of Radiology at Institut Franco-European de Chiropratique, Paris. She completed her fellowship in musculoskeletal radiology at the Department of Osteoradiology, Veterans Affairs Healthcare Center, San Diego, under Donald Resnick, MD, professor of radiology. Wessely provides a film-reading service for chiropractors and lectures to both chiropractic undergraduates and postgraduates in Europe. She can be reached at: mwessely@ifec.net; michelle_wessely@yahoo.com; (033) (0)1 45 15 89 10.

References
1. Kanis JA, Johnell O, Oden A, Borgstrom F, Zethraeus N, De Laet C, Jonsson B. The risk and burden of vertebral fractures in Sweden. Osteoporos Int. 2004;15(1)20-26.
2. Magerl F, Aebi M, Gertzbein SD, Harms J, Nazarian S. A comprehensive classification of thoracic and lumbar injuries. Eur Spine J. 1994;3(4):184-201.