Burst Fracture

Overview

A burst fracture is a high-energy injury in which a vertebral body fails catastrophically under axial compression, shattering into multiple fragments that are displaced outward, including, critically, a posterior fragment driven back into the spinal canal. Unlike a simpler wedge compression fracture, which disrupts only the front column of the spine, a burst fracture by definition compromises the middle column (the posterior vertebral body wall and the posterior longitudinal ligament) and may also damage the posterior column. This multi-column involvement is what distinguishes a burst pattern from less severe fracture types and raises concern for mechanical instability and neural injury.

The injury occurs most often at the thoracolumbar junction, roughly between T10 and L2, where the relatively rigid thoracic spine meets the more mobile lumbar spine, concentrating mechanical stress at that transition zone. The natural history of a stable, neurologically intact burst fracture is generally gradual healing over several months; unstable or neurologically involved injuries carry a higher risk of deterioration without timely intervention.

What causes it

The underlying mechanism is vertical loading transmitted through the intervertebral disc into the vertebral endplate, which drives disc material into the cancellous bone and causes the vertebral body to shatter outward. Burst fractures occur in two distinct patient groups.

The larger group consists of younger adults, predominantly men, who sustain high-energy trauma such as motor vehicle collisions, falls from height, or sporting and industrial accidents. In these patients the bone itself is normal; the failure reflects the sheer magnitude of the applied force.

A second, growing group comprises older adults with osteoporosis or other causes of reduced bone density, in whom comparatively minor axial loading can produce a burst pattern. Conditions that further weaken the vertebra (metabolic bone disease, chronic corticosteroid use, prior radiation therapy, or an underlying tumor) should prompt consideration of a pathologic process when the injury seems disproportionate to the event. Inflammatory spinal conditions such as ankylosing spondylitis or diffuse idiopathic skeletal hyperostosis create a rigid, brittle spine that is also susceptible to unstable fractures from relatively low-energy trauma.

Symptoms and warning signs

Patients typically present with acute, severe back pain localized to the injured level, with focal tenderness and paraspinal muscle spasm. Pain is markedly worse with any movement or attempt to bear weight.

Because most burst fractures result from high-energy trauma, associated injuries (to the head, chest, abdomen, pelvis, and heels) are common and must be actively looked for. Neurological involvement can range from none at all to a complete deficit, depending on the degree of canal compromise and the energy transmitted to neural structures.

Several findings are urgent red flags requiring emergency evaluation. Progressive weakness or loss of feeling in the legs signals ongoing or worsening neural compression. Saddle anesthesia (numbness in the groin, inner thighs, and buttocks), inability to urinate, or loss of bowel control are the hallmarks of cauda equina syndrome, a surgical emergency. Any sign of acute spinal cord or conus medullaris injury is equally urgent. An unstable injury pattern with potential for further displacement also warrants immediate specialist assessment.

How it's diagnosed

Diagnosis rests on the combination of mechanism, physical examination (including a careful motor, sensory, reflex, and saddle-region neurological assessment), and imaging.

Plain X-rays may show loss of vertebral body height, widening between the pedicles on the front-to-back view, and disruption of the posterior vertebral body line, but they consistently underestimate canal narrowing and injury to the posterior structures.

CT scan is the standard for characterizing a burst fracture. It demonstrates comminution, retropulsed fragments, the degree of canal narrowing, and any fractures of the posterior arch, and it is essential for surgical planning.

MRI is indicated when there is any neurological deficit, when injury to the posterior ligamentous complex is suspected, or when the spinal cord, conus, or cauda equina must be evaluated directly. MRI best shows cord edema, epidural blood or fragment compression, and ligamentous disruption, and it helps identify an underlying tumor or infection when the injury seems out of proportion to its mechanism.

Formal classification systems, including the Thoracolumbar Injury Classification and Severity score (TLICS) and the AOSpine system, integrate fracture morphology, neurological status, and ligament integrity to guide management. Imaging must always be interpreted alongside the clinical examination, because radiographic severity and neurological status do not always correspond.

Treatment options

Management is stratified by mechanical stability and neurological status.

Conservative (non-operative) treatment is appropriate for many burst fractures that are stable and neurologically intact. This typically involves adequate pain management, a supportive brace, most often a thoracolumbosacral orthosis (TLSO), worn for approximately six to twelve weeks, and a supervised, graduated mobilization program. Serial clinical and imaging follow-up is essential to confirm healing and detect any progressive deformity.

In older patients with osteoporosis-related fractures, bone-health evaluation and medical treatment to address bone density are important components of the overall care plan. Selected painful, stable fractures in this population may be candidates for cement augmentation procedures such as kyphoplasty, which can reduce pain and stabilize the vertebra. Because a burst fracture disrupts the posterior vertebral body wall, cement augmentation carries a higher risk of cement leaking backward into the spinal canal, where it can injure neural structures. For this reason it is used selectively and only when the posterior cortex is adequately competent.

When surgery is considered

Surgery is indicated when any of the following are present: a neurological deficit, particularly a progressive one, indicating ongoing cord or cauda equina compression; frank mechanical instability or significant disruption of the posterior ligamentous complex; substantial canal narrowing with cord or nerve compression; or progressive kyphotic deformity that cannot be managed non-operatively.

Surgical options include posterior instrumented stabilization and fusion, anterior decompression with vertebral body reconstruction, or combined anterior-posterior approaches. The goals are to decompress the spinal cord and nerve roots, restore spinal alignment, and provide stable fixation. When acute or worsening cord or cauda equina compression is identified, urgent decompression is appropriate. Rehabilitation and ongoing monitoring for delayed instability or deformity remain important components of care across all treatment pathways.