Thoracolumbar Spine Fracture

Etiology

Injury to the thoracolumbar spine can occur from motor vehicle accidents, falls from height, recreational accidents, and occupational injuries. Because the thoracolumbar junction is more vulnerable than other segments of the spine, it is a very common area of injury due to its intrinsic biomechanics.[1]

In the event of high-velocity spine injuries, there is an associated 25% risk for accompanying spinal cord injury (SCI), which can subsequently have devastating effects on the patient with loss of individual productive years and an associated high cost to society.[4] As many as 25% of thoracolumbar fractures have another spine fracture elsewhere, most commonly the cervical spine.[5]

Epidemiology

Thoracolumbar traumatic injury was most commonly reported in the 15-29 year age group before 2000, but now the median age is 35. Approximately 27% of the patients with thoracolumbar junction injuries had neurological deficits, which results in detrimental effects on society due to lifelong disability and loss of productive economic years.[6] Approximately 70% of these fractures occur without immediate neurological injury, and eventually, 55% remain neurologically intact. Of the 45% who develop neurological symptoms, 26% develop an incomplete injury, and 19% develop a complete injury. Up to 75% of spine fractures occur in the T10-L2 area.[7] 

According to the United States National Spinal Cord Injury Statistical Center, in approximately 54 cases per million people, 17,000 new spinal cord injury cases occur each year.[8] Over 250,000 patients are currently living with permanent deficits. Blunt trauma is associated with an incidence of 1.9% thoracic fractures.[8]

The incidence of thoracolumbar junction fractures after motor vehicle accidents is approximately 2.4%, but it has been increasing over the years.[9] In blunt trauma patients, thoracolumbar junction fractures had an incidence of 6.9%.[6] A review of patients with blunt trauma who underwent a chest/abdomen/pelvis computed tomographic (CT) scan showed that up to 25% had thoracolumbar fractures.[10] Several fractures were undetected in the plain X-ray films. In adults, motor vehicle accidents were the most common mechanism in 36.70% of the cases, followed by falls from height for 31.70%.[6] For people with paraplegia, the average lifetime costs are approximately 2.5 million dollars per patient.

A report from China found a thoracolumbar junction fracture incidence rate of 2.4 patients per million with a mean age of 49 years, with a male to female ratio of 1.4:1.[11]

In children, thoracolumbar fractures are rare, with a reported incidence as low as 2% of all spine fractures. However, other series have reported an incidence of 5%-34%.[12] The most common mechanism is falling from a height, with 25% presenting a complete deficit, and approximately 20% requiring surgery.[12][13][14]

Pathophysiology

Transitional zones of the spine have a characteristic higher degree of flexibility and degrees of motion; however, this can make these segments more prone to injury. The thoracolumbar region is a fulcrum between the more rigid thoracic segment with facets that are coronally oriented to prevent flexion-extension, translation, and rotation and the lumbar segment whose facets are oriented sagittally to allow flexion-extension movement.[5] This anatomical setup makes the T10-L2 segment the most mobile and vulnerable portion of the spine. Also, at the transitional point for the thoracic spine (T11 and T12), the ribs do not articulate anteriorly with the sternum, distinguishing them as floating ribs. At the thoracolumbar junction, the stiff kyphotic thoracic spine meets the caudal lordotic lumbar spine.

The kinetic energy conveyed to this region can make it vulnerable to degenerative disease pathologies and traumatic injuries in higher energy mechanisms.[5][15] Energy transferred from an impact at any anatomical level of the spine can accumulate and produce stress in the thoracolumbar junction. Many biochemical changes occur secondary to the impact, including ischemia, free radicals, vasoconstriction, intracellular influx of calcium ions, lipid peroxidation, and excitotoxins.[16]

History and Physical

The majority of thoracolumbar junction fractures result from high impact trauma, including motor vehicle accidents and falls. A detailed patient history helps contextualize the type of mechanism involved in the injury. This will be most relevant in the neurologically stable patient.[5] A low energy mechanism such as a ground-level fall is usually without associated neurological injury. Patients can present with associated neurological injury, which will show signs and symptoms during the neurological exam.[5] 

If the patient is critically ill and on mechanical ventilation, history will have to be obtained from family members, paramedics, other clinicians, and the patient's medical chart. Associated back pain with details such as location, quality, character, duration, and aggravating factors are standard attributes to be assessed and critical for associated injuries in other systems.

The patient who suffered a thoracolumbar junction fracture may present on a physical exam with intact function, incomplete deficits, or complete neurological deficits. The level of injury at the conus region can determine the deficit that the patient presents with. If the affected area is in the transition area, it can cause symptoms of both upper and lower motor neuron dysfunction.[17] 

If the lesion is above the conus, only upper motor signs and symptoms will be elicited; if the lesion is below, then lower motor signs and symptoms will be found. Patients usually have a mix of upper and lower motor neuron symptoms due to many exiting nerve roots from the conus medullaris in this region. Injuries that occur above T10 are more likely to result in complete neurological deficits, while injuries below L1 are more likely to result in radicular symptoms. This is due to the anatomic position of the spinal cord, where the conus medullaris usually do not extend below the level of L1.

There may be overt signs on the physical exam such as widened spaces between spinous processes or displacement of spinous processes from the midline, which can be seen in the patient's physical exam on palpation and inspection when the patient is rolled over in the primary trauma survey.

A complete motor and sensory examination is performed with the cooperative patient. Once this information has been obtained, the American Spinal Injury Association (ASIA) score can be assigned to the patient's neurological physical exam.[18] It is critical to evaluate the bulbocavernosus reflex to determine if the patient is in spinal shock. If hyperactive, it probably represents a complete spinal cord injury. A rectal exam is done to assess tone.

Evaluation

Initial triage is performed using the primary ATLS survey, ensuring that the airway is secured, breathing and ventilation are adequate, and there is proper cardiovascular support. After this initial assessment, the secondary survey focused on the spine will consist of a motor and sensory examination to determine the SCI level. The rectal exam for evaluation of tone, voluntary contraction, and sensation should never be overlooked. If the patient is critically ill and on mechanical ventilation, with associated head injuries such as traumatic brain injury (TBI), the rectal tone may be the only objective finding of the neurological physical exam in patients with SCI. The international standards for neurological classification of spinal cord injury, commonly referred to as the ASIA exam, was developed as a universal classification tool for SCI based on a standardized sensory and motor assessment.[18] It is a system used to define and describe the extent and severity of a patient's SCI and determine future rehabilitation and recovery needs.[19] It is ideally completed within 72 hours after the initial injury.[20] The patient's grade is based on how much sensation and movement are detected below the injury level.[21]

American Spinal Injury Association (ASIA) impairment scale:[18][22]

• A - Complete: No motor or sensory function is preserved below the neurological level
• B - Incomplete: Sensory function preserved but no motor function is preserved below the neurological level including the S4–S5 segments
• C - Incomplete: Motor function is preserved at the most caudal sacral segments for voluntary anal contraction. The motor function below the neurological level is preserved with less than half of key muscles that have a muscle grade ≥ 3
• D - Incomplete: Motor function is preserved below the neurological level with at least half of key muscles that have a muscle grade ≥ 3
• E - Normal: Motor and sensory function are normal

In the setting of a traumatic event suffered by the patient, especially a high-energy mechanism, it is imperative that full spinal imaging is performed as soon as the primary survey is completed. This should be performed once the patient is stabilized from acute life-threatening injuries (shock, TBI). Delaying time to image acquisition in an SCI setting with a neurological deficit may be detrimental to the patient by potentially decreasing the maximal benefit of early surgery. Delayed diagnosis of a thoracolumbar fracture or injury can occur in up to 5% of patients. In the case of unstable thoracolumbar fractures, it can result in neurologic deficits and pain.[23][24]

Therefore, it is important for clinicians, including emergency department clinicians, traumatologists, neurosurgeons, paramedics, and other associated healthcare professionals, to have a high degree of suspicion when evaluating the patient. Regardless of whether the patient has a spine fracture or injury, a high suspicion makes the use of spine immobilization and precautions mandatory, until a spine fracture is ruled out. There are no validated algorithms to direct decision-making in terms of which patients benefit from thoracolumbar imaging studies and which do not.[24]

Imaging of the spine can include simple spine x-ray films, CT scans, or magnetic resonance imaging (MRI). Spine x-ray films usually do not provide the amount of detail to characterize the type of fracture and are not routinely used.[25] In some situations, plain radiographs, if they are the only modality available, can detect fractures or evaluate bone instability. On the other hand, a CT scan and MRI provide a higher resolution of structures. They allow an understanding of the type of fracture, which will subsequently influence the proposed treatment options.

CT scan will give an adequate assessment of bony structures, including the vertebral bodies, pedicles, laminae, facets, and transverse and spinous processes. In contrast, MRI will provide a better assessment of the ligamentous and the neural structures, including the spinal cord, cauda equina, conus medullaris, and spinal nerve roots. Therefore, in the case of a patient presenting with neurological deficits, MRI will most likely be performed for a complete management algorithm. Neurosurgery or orthopedic spine surgery services should be consulted as soon as images are obtained for proper evaluation and recommendations. If there is a documented neurological deficit on the physical exam of the patient and initial CT scan images are negative for fractures or dislocations, it is essential to perform an MRI. The MRI can identify bone marrow edema associated with an occult fracture, soft tissue changes, annular disruption, disruption of the posterior ligamentous complex, hemorrhage, herniated disk material, and the status of the spinal cord.

Although plain simple radiographs are not routinely used in the initial diagnosis and management of thoracolumbar junction fractures, they remain useful in the operating room, serving to aid with a proper assessment of the sagittal alignment, fracture level localization, and graft-construct positioning. They also serve as an inexpensive alternative on long-term surveillance for the development of deformity or pseudoarthrosis with considerably less radiation exposure per study than the CT scan. 

Different classification schemes have been proposed by committees of clinicians and spine surgeons, and unfortunately, many early classification systems relied primarily on imaging findings alone. More modern and recent classification algorithms have been developed. The paradigm has shifted to include aspects of the neurological physical examination, such as deficits. The Spine Trauma Study Group developed a comprehensive classification system with prognostic significance that helps guide treatment decisions for operative versus nonoperative management of thoracolumbar junction fractures, called the thoracolumbar injury classification and severity (TLICS) scale.[26][27] 

Criteria involved in the classification system include the integrity of the posterior ligamentous complex, the injury mechanism or morphology of the fracture, and the presence of neurological injury.[28] The fracture's morphology serves as a surrogate for immediate stability, whereas disruption of the posterior ligamentous complex serves as a surrogate for long-term stability. The comprehensive TLICS system can be seen below, in which a score of less than 4 suggests conservative treatment, and a score of greater than 4 suggests surgical intervention. If a patient has a score of 4, the surgeon can recommend surgical versus conservative management, with both options being accepted.

Thoracolumbar injury classification system (TLICS):[26][27]

1. Injury mechanism/fracture morphology (as evidenced by radiographs or CT scan)
1. Compression: 1 point
2. Burst: 2 points
3. Translation/rotation: 3 points
4. Distraction: 4 points
2.  The integrity of the posterior ligamentous complex (as evidenced by MRI)
1. Intact: 0 points
2. Suspected/indeterminate: 2 points
3. Injured: 3 points
3.  Neurological status (as per the physical exam)
1. Intact: 0 points
2. Nerve root: 2 points
3. Complete cord: 2 points
4. Incomplete cord: 3 points
5. Cauda equina: 3 points

Compression fractures are the most common injuries and are usually stable injuries with intact posterior elements. Burst fractures have the anterior column and the posterior column involved and typically have retropulsed bone into the canal. Flexion-distraction injuries usually are one or two-level hyperflexion injuries through the soft-tissue ligaments or the bony structures. These involve the anterior and posterior columns and the posterior ligaments, including the ligamentum flavum, and represent an unstable injury as the fracture typically extends through the ligament and the anterior and posterior columns. Fracture dislocations are unstable and should be stabilized at the earliest possible opportunity.[5]

Treatment / Management

Spinal precautions should be implemented in all trauma patients until a spine fracture is ruled out. Limiting flexion, extension, rotation, and twisting of the spine can help avoid exacerbating an injury to the spinal cord. Precautions can be lifted once radiographic images and physical exams are reassuring for no spinal instability. Maintaining perfusion to the spinal cord with supportive care, including airway, breathing, and circulation management with a mean arterial pressure above 85 mmHg, is essential to enhance spinal cord perfusion. Based on the amount of instability or neurological involvement, the patient may require emergency surgery.

Injuries at the thoracolumbar junction, although very common, comprise a heterogeneous group of injuries that has led to an increased discrepancy over the ideal surgical or nonsurgical management. The TLICS scale can provide insight into the treatment of the patient’s spinal fracture. Many surgeons agree that the concept of spine stability is one of the most critical factors in deciding if the thoracolumbar junction fracture require surgical treatment or can be managed conservatively. Disruption of the posterior ligamentous complex integrity raises the likelihood of instability when identified by MRI.[29][30][31][32][33] Even without neurologic injury, many of these fractures will require operative intervention for stabilization due to the degree of bony or ligamentous injury that may be present.(B3)

Different studies have addressed the management of thoracolumbar fractures, with some prospective randomized controlled trials comparing operative versus conservative management of thoracolumbar burst fractures, reporting no clinically significant advantage with surgery.[5][15][34][35][36][37][38] (A1)

Conservative management techniques include thoracolumbar orthosis, plaster cast, Jewett brace, and a plastic body cast for approximately 12 weeks. The majority of the compression fractures are stable and are treated with simple observation or an orthosis.[5] 

For surgical intervention, approach alternatives include anterior, posterior, lateral, or combined approaches. The operative planning and stabilization of these fractures usually include a multifactorial decision-making process. The key factor for deciding an anterior versus a posterior approach is the location of the pathology to be addressed. Different techniques include posterior segmental instrumentation and fusion with or without posterior decompression, percutaneous pedicle screw instrumentation, lateral interbody fusion, and anterior column fusion. Spinal neuromonitoring is routinely used during the surgery. Postoperative bracing does not offer an advantage after surgical stabilization; however, it can be used for comfort.[36](A1)

Burst fractures are stable if the posterior osteoligamentous complex and facet capsules are intact. Stable burst fractures can be treated with an orthosis. If unstable, posterior pedicle screw fixation of the adjacent levels is performed. If an anterior surgery is performed, the fractured bone is removed, and the defect filled with a solid bone graft or a metallic or synthetic cage. This technique restores the anterior column. Flexion-distraction injuries damage the posterior osteoligamentous complex. They are treated with posterior instrumentation and fusion over several levels to restore the sagittal alignment. Fracture-dislocations are very unstable and are treated with early decompression and posterior multilevel instrumentation and fusion.[5] Many surgeons perform minimally invasive procedures to reduce the morbidity of open surgery for thoracolumbar spine trauma.

Differential Diagnosis

After a recent history of trauma, with new evidence of neurological deficit or pain, a traumatic fracture is commonly encountered, but pre-existing disorders have to be excluded.

• Anatomical variant
• Osteoporosis fracture
• Ankylosing spondylitis
• Stiff-spine diseases
• Spine tumor
• Spine metastatic disease
• Pseudoarthrosis from previous spine instrumentation

Prognosis

Thoracolumbar junction fractures can have devastating effects on a patient's general healthcare and society with loss of individual productive years and associated exorbitantly high costs.[4] In a systematic review, there is no advantage of a technique for one conservative management over another.[39]

Factors for the development of neurological deficits include the sagittal diameter of the spinal canal and the amount of anterior vertebral compression.[40] The degree of neurological recovery depends on fracture type, location, ASIA score, and presence of comorbidities. Early intervention in patients with neurologic deficits allows for a better prognosis.[41]

Patients with ASIA impairment score D or E can recover and return to a health status similar to the population norms.[42] Those patients with more significant neurologic deficits are less likely to return to work.

Complications

• Sepsis
• Aspiration bronchopneumonia
• Neurological deficits
• Deep venous thrombosis
• Surgical wound infection
• Cerebrospinal fluid leakage
• Pseudoarthrosis
• Adjacent level disease
• Excessive blood loss during surgery
• Anesthesia-related complications