Approach Considerations
Although Chance fractures may generally be managed by means of closed reduction and immobilization in a thoracolumbosacral orthosis (TLSO) or hyperextension cast, surgery may be indicated in some cases. Exogenous obesity may be a relative contraindication for the usual nonoperative management of Chance fractures because it may render bracing difficult. In these instances, as well as in cases of multiple trauma, an operative approach may be indicated to stabilize these injuries.
Nonoperative Therapy
Chance fractures can generally be reduced by placing the patient on a Risser table with hyperextension applied to the thoracolumbar junction. A fiberglass or plaster cast is then applied. Alternatively, a mold may be taken and a TLSO made for stabilization. Patient selection is important to ensure compliance with orthosis use.
Once the flexion-distraction injury through the bony elements is approximated and the kyphosis is reduced through extension of the thoracolumbar spine, the patient is maintained in the TLSO or hyperextension cast for 2-3 months. After immobilization, an upright lateral radiograph should be obtained to assess any residual deformity. The union rate is high and the results are good with closed management.
A case report by Park et al described successful treatment of an unstable bony Chance fracture with teriparatide and an orthosis in a patient with diffuse idiopathic skeletal hyperostosis. [26]
A rehabilitation program consisting of extension exercises can be instituted, and most individuals return to work within 6 months. Residual backache may be a problem for the first year after the injury.
Surgical Therapy
If immobilization is impractical (eg, because of a large body habitus) or the patient has polytrauma, surgical management may be indicated.
A posterior approach to reconstruct the posterior tension band is preferred. This may be accomplished with either a rod-hook, a hook–pedicle screw–rod, or a pedicle screw–rod construct, depending on the individual patient's anatomy and the location of the injury. A similar operative approach may be used with ligamentous variants. Decompression usually is not a result of residual compression in this injury; realignment of the spine is of the utmost importance, followed by stabilization and arthrodesis.
With the advent of percutaneous and minimally invasive techniques for pedicle-screw insertion, these devices may be applied more easily in multiple-trauma patients and others in whom closed management would be impractical. [27, 28] In a meta-analysis focused on open versus minimally invasive fixation for traumatic thoracolumbar fractures, McAnany et al found minimally invasive fixation to have advantages with respect to blood loss and operating time, though there were no significant differences between the two approaches with regard to vertebral body height, kyphosis angle, or visual analogue scale (VAS) score. [29]
Le et al emphasized the importance of defining the pattern of injury in the pediatric population to determine appropriate treatment. [30] Arkader et al concluded that surgical treatment in children provides the best results. [31]
Operative details
If operative intervention is selected, computed tomography (CT) detailing the pedicle anatomy is helpful in selecting the appropriate fixation device. If a neurologic injury is present, magnetic resonance imaging (MRI) may be helpful as well.
Because a Chance fracture involves a flexion-distraction mechanism, placing the patient on rolls providing an extension moment or on the Jackson table prone frame aids in the reduction of this injury.
In a midline approach to the thoracolumbar junction, a level above and a level below the affected area should be dissected. Once the dissection has extended down to the tip of the spinous processes, subperiosteal dissection with Cobb elevators is carried out to the facet joints bilaterally. Further dissection around the facet joints to the transverse processes is performed to complete the exposure necessary for instrumentation.
Surgical gauze for packing the lateral gutters is invaluable in assisting with hemostasis. At each level, troublesome bleeding can be encountered from segmental vessels around the facets and pars interarticularis.
Instrumentation may involve as little as one level above and below the injured site, if pedicle-screw fixation is possible. However, standard hook fixation may be used to incorporate two levels above and one or two levels below the zone of injury. A hybrid construct consisting of hooks above and pedicle screws below is also an option.
Closure in layers is performed after a standard posterior lateral arthrodesis is performed. Meticulous decortication of the transverse processes, pars, and lateral aspect of the facet joints should be completed before application of autologous bone grafting.
Postoperative Care
With optimal surgical fixation, early mobilization should be possible. The usual postoperative concerns of bowel and bladder function and advancing diet should be addressed carefully and individually. Deep vein thrombosis prophylaxis can usually be provided by using compression hose and intermittent dynamic compressive devices, such as a foot pump or Venodyne boot. Other means of anticoagulation may be employed on a case-by-case basis, with care taken to weigh the risks of such therapy against its benefits.
Complications
The most common complications are residual kyphosis and chronic mechanical back pain. Pressure injuries under a cast can be avoided with proper padding and cast application and with frequent turning of the patient. Such injuries can also be avoided by fostering early mobilization. [32]
Long-Term Monitoring
Arthrodesis usually is complete by 6 months, if not sooner, in younger patients. A rehabilitation program can be instituted as healing progresses and should include a walking routine and back exercises for mobilization and strengthening.
Follow-up radiographs should be obtained at monthly intervals to ensure progressive healing and maintenance of spinal alignment.
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Chance fracture or modified compression fracture of upper lumbar spine may occur when weight of upper body moves forward (red arrow) while person's waist and upper body are fixed in position by seatbelt or steering wheel of automobile (pink arrows). Consequent fixed-position stress results in fracture.
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Anterior view of Chance fracture of L2 vertebral body. Fracture line follows horizontal plane through L2 vertebral body and transverse processes (arrows).
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Drawing of Chance fracture of thoracolumbar junction. Defect follows irregular horizontal plane (arrows), which results in disruption of anterior (black dotted line), middle (red dotted line), and posterior columns (blue dotted line).
