Thoracolumbar fractures account for 90% of spinal fractures, with the thoracolumbar burst fracture. subtype corresponding to 20% of this total.
There are approximately 15,000 thoracolumbar fractures each year in the U.S., and nearly 1/3 of these injuries are associated with a neurologic injury.
The majority of thoracolumbar injuries occur at the T11-L1 level, which is the transitional zone between the relatively immobile thoracic spine and flexible lumbar spine. A low-energy injury is more likely to cause an injury to the intervertebral disc, yet a high-energy trauma such as a motor vehicle accident or fall is more likely to fracture the bone. Thoracolumbar fractures and dislocations are typically classified according to their injury/fracture pattern, as described by Denis.
The causes of thoracolumbar fracture are different depending on patient's age. In younger patients, fracture is more likely to occur due to a high-energy trauma, such as motor vehicle accident, motorcycle accident, and falling injury. However, in elderly, even falls from standing position to ground can cause fractures due to osteoporosis and decreased cognition.
Fracture dislocation of the thoracic spine is a rare spine injury often resulting from high-energy trauma. Associated soft-tissue thoracic injuries are common and are compounded by the often-associated paraplegia. Exceptionally, there are some cases of thoracic spine dislocations without neurological injuries 1).
Patients suffering high-energy injuries are at risk for occult thoracic spine fracture and lumbar spine fractures, and the standard of care includes radiographic spine screening. Most such patients require computed tomographic (CT) scanning to screen for chest and/or abdominal visceral injury.
For accurate classification, radiographs alone were insufficient except for C-type injuries. CT is mandatory for accurately classifying thoracolumbar fractures. Though MRI did confer a modest gain in sensitivity in B2 injuries, the study does not support the need for routine MRI in patients for classification, assessing instability or need for surgery 2).
Twenty to forty percent of fractures are associated with neurologic injuries.
If the patients involve in a severe trauma, the complications, such as paralysis and deformity, may occur after that accident. Even if the patients do not experience any complications, there could be limits of daily activities or difficulty to return to work due to chronic pain.
A retrospective review of adult patients, with single-level, TLJ (T11-L2) fractures, treated with posterior fixation between 2007 and 2014 at a regional spinal centre. Short segment posterior fixation (SSPF) and Long segment posterior fixation (LSPF) were defined as pedicle screw fixation at one and two levels above and below the vertebral fracture, respectively. Construct failure was defined as instrument breakage or screw pull-out requiring operative intervention. Two independent assessors measured the kyphotic Cobb angle at up to six months.
A total of 28 patients were included with a median age of 38 years (range 20-76 years) and median follow-up period of 14 months (4-41 months). All patients sustained traumatic fractures and the male to female ratio was 19:9. AOSpine Thoracolumbar Classification System classes were: A (29%), B (50%) and C (21%). SSPF and LSPF were performed in 17 (61%) and 11 (39%) patients, respectively. There was no significant difference in age (Fisher's exact, p > 0.99), AO fracture class (chi-squared, p = 0.510), preop TLICS score (independent t-test, p = 0.668) and length of stay (independent t-test, p = 0.106) between the groups. Construct failure occurred in three SSPF cases (3-14 months postop) and was associated with an increased mean loss of correction. By six months, the Cobb angle had increased significantly in the SSPF group (paired t-test, p = 0.049), but not the LSPF group (paired t-test, p = 0.157).
Data identified a trend towards better clinical and radiological outcomes in the LSPF, compared to the SSPF group. Although supported by some studies, these findings should be evaluated in future clinical trials 3).
From a retrospective study of 412 thoracolumbar region injuries, Denis introduces the concept of middle column or middle osteoligamentous complex between the traditionally recognized posterior ligamentous complex and the anterior longitudinal ligament. This middle column is formed by the posterior wall of the vertebral body, the posterior longitudinal ligament and posterior annulus fibrosus. The third column appears crucial, as the mode of its failure correlates both with the type of spinal fracture and with its neurological injury. Spinal injuries were subdivided into minor and major. Minor injuries are represented by fractures of transverse processes, facets, pars interarticularis, and spinous process. Major spinal injuries are classified into four different categories: compression fractures, burst fractures, seat-belt-type injuries, and fracture dislocations. These four well-recognized injuries have been studied carefully in clinical terms as well as on roentgenograms and computerized axial tomograms. They were then subdivided into subtypes demonstrating the very wide spectrums of these four entities. The correlation between the three-column system, the classification, the stability, and the therapeutic indications are presented 4).
Modern Thoraco-Lumbar Implants for Spinal Fusion
This book presents an updated perspective on spinal implants currently used in thoracolumbar spine surgery, leading to a rigid or dynamic stabilization. The development of new surgical devices and techniques is mostly focused on a spinal fusion for lumbar instability due to trauma, tumours or degenerative or infectious diseases. Pedicle screw fixation and fusion are currently considered to be the gold standard for most of the above-mentioned pathologies, and modern implants are designed to improve the accuracy of pedicle-screw placement and to allow the use of new surgical techniques and minimally invasive approaches. The content is relevant for surgeons, orthopaedic specialists, neurosurgeons, physiotherapists and osteopaths.