- Classification of Burst Fracture
- Thoracolumbar Injury Classification and Severity Score
- Presentation of Burst Fracture
- Treatment of Burst Fractures
- Gain Knowledge - Stay Healthy
Burst fractures are defined as vertebral fracture with the failure of the anterior and middle column. The fractures are unstable as there is involvement of two columns, anterior and middle, out of three columns of the spine.
Burst fractures are caused by axial loading with flexion and can be considered as high energy compression fractures that result in disruption of the posterior vertebral body cortex with retropulsion into the spinal canal.
L1 is the most common vertebra involved with the majority of the burst fractures occurring at T9-L5.
Majority of these fractures are single level fractures.
Denis Classification of Vertebral Column
Denis gave three column classification of vertebral column where vertebral column could be thought of as consisting of three columns which are
- Anterior longitudinal ligament
- Anterior 2/3 of vertebral body and annulus
- Posterior longitudinal ligament
- posterior 1/3 of vertebral body and annulus
- Ligamentum flavum
- Spinous process
- Posterior ligament complex
- Supraspinous ligament
- Interspinous ligament,
- Ligamentum flavum
- Facet capsule.
Mechanism of Injury
Injury to just anterior column results in a wedge-shaped vertebra and is called a compression fracture. Injury to middle column means the vertebral body is crushed in all directions and it is called a burst fracture.
The term burst fracture implies that the margins of the vertebral body spread out in all directions. This is a much more severe injury than a compression fracture for two reasons. With the bony margins spreading out in all directions the spinal cord is liable to be injured. The bony fragment that is spread out toward the spinal cord can bruise the spinal cord causing paralysis or partial neurologic injury.
Neurologic injury from a burst fracture ranges from no injury at all to complete paralysis and generally correlates with severity of the injury. The neurologic deficit may cause loss of strength, sensation or reflexes below the level of the injury and may even cause paralysis of the legs and loss of control of the bowel and bladder.
These occur typically following a fall from height (often landing on feet) or from a motor vehicle accident.
High-energy compression force drives the intervertebral disc into the vertebral body below.
The anterior cortex fails in compression, either or both the end plates can get fractured The middle column also fractures, and a portion of the body gets retropulsed backward into the canal. The posterior elements may also get fractured.
There is often canal compromise often caused by retropulsion of bone. The maximum canal occlusion and neural compression occur at the moment of impact.
The retropulsed fragments get resorbed over a period and are not associated with progressive deterioration of neural deficit.
They typically occur from severe trauma, such as a motor vehicle accident or a fall from a height.
Injury to middle column results in instability of the spine. Injury to middle column can be gauged by noting by widening of interpedicular distance on AP radiograph and loss of height of posterior cortex of vertebral body.
dInjury to posterior complex further adds to instability. Posterior complex injury results in widening of widening of interspinous distance, progressive kyphosis with nonoperative treatment
In case the PLC status is doubtful, increased signal intensity on the MRI suggests PLC injury.
Classification of Burst Fracture
Burst fractures may be subdivided by fracture pattern as follows [Dennis classification]
This type of injury occurs with axial loading and it results in fractures of both upper and lower end-plates. The bone is retropulsed into the canal.
This is the most common type of burst fractures and accounts for almost 50% of the burst fractures. In this injury only the superior end-plate is fractured.
Burst rotation. It is a very uncommon injury and results in disruption of only the lower end-plate. The mechanism of this injury is a combination of axial load and rotation.
In this injury, rotational displacement of one body relative to the other occurs
Burst lateral flexion. This type of fracture differs from the lateral compression fracture in that it presents an increase of the interpediculate distance on anteroposterior roentgenogram.
Thoracolumbar Injury Classification and Severity Score
It is a scoring system of thoracolumbar injuries that guides on treatment as well.
It is based on the following elements
- Compression (1 point)
- Burst (+1 point)
- Rotation/translation (+3 point)
- Distraction (+4 point)
- intact (+0 point)
- Nerve root (+2 point)
- Incomplete Spinal cord or conus medullaris injury (+3 point)
- Complete Spinal cord or conus medullaris injury (+2 point)
- Cauda equina syndrome (+3 point)
Posterior ligamentous complex integrity
- Intact (+0 point)
- No interspinous ligament widening seen with flexion views.
- MRI shows no edema in interspinous ligament region
- Suspected/indeterminate (+2 point)
- MRI shows some signal in the region of interspinous ligaments
- Disrupted (+3 point)
- widening of the interspinous distance
All scores are added to calculate the total score
- < 4 – Nonoperative management
- 4 – choose between nonoperative or operative treatment
- > 4 points – Surgical manangement
surgical management indicated
Presentation of Burst Fracture
Burst fracture causes severe pain at the level of the fracture and may radiate to lower limbs too. The physical exam should be performed to document both spinal deformity, that is, angulation of the spine or tenderness of the spine at the level of fracture, as well as, a neurologic exam.
Neurologic exam should include testing of the muscle strength, sensation, and reflexes of the lower extremities, as well as, testing of bowel and bladder sphincter control.
Xrays are a basic investigation and it is recommended to view entire spine as concomitant spine fractures may be present.
AP view shows widening of pedicles. The lateral view shows retropulsion of bone into the canal and kyphotic deformity
CT defines the fracture better. It is done in cases where the x-ray films are inadequate and there is neural deficits.
It is useful to evaluate spinal cord or thecal sac compression and provides insight to the amount of injury to the cord.
It also highlighrs cord edema or hemorrhage and injury posterior ligament complex
Treatment of Burst Fractures
The treatment ambulation with or without orthosis.
Indications of Non-opertaitve Treatment
- Mechanically stable patients without neural deficit
- Kyphosis<30 degrees
- Vertebral height loss < 50%
- Neurologically intact and mechanically stable patients
- TLICS score is 3 or less
- Spinal canal compromise is less than 50 percent.
In these patients, treatment with a brace may lead to an excellent result. Bracing can be used to immobilize stable burst fractures. It can be in form of Thoracolumbosacral orthoses or extension cast. The usual period of immobilization is for 3 months. After brace is applied, the patient is radiographed to check stability, loss of height or increase in kyphosis [All these indicate underlying posterior ligamentous insufficiency].
If everything is satisfactory, the patient is mobilized with physical therapy.
Frequent x-rays for follow up are done. Occasionally, a fracture that was thought to be stable and treated in a brace may begin to angulate while in the brace. This may necessitate a later decision to perform surgery.
Recent studies have suggested no clear advantage of orthosis but if it provides the patient a relief, it should be given.
The retropulsed fragments resorb over time and usually do not cause neurologic deterioration.
surgical decompression & spinal stabilization indications neurologic deficits with radiographic evidence of cord/thecal sac compression both complete and incomplete spinal cord injuries require decompression and stabilization to facilitate rehabilitation unstable fracture pattern as defined by injury to the Posterior Ligament Complex (PLC) progressive kyphosis lamina fractures (controversial) TLICS score = 5 or highe Operative Treatment Surgical treatment of the burst fractures involves decompression and stabilization. The spine can be approached through an anterior and posterior approach. Unstable burst fractures usually do better with early surgery. A burst fracture is considered unstable if the neurologic injury is present, angulation of the spine is greater than 20 degrees, there is subluxation or dislocation of the spine, or there is greater than 50 percent spinal canal compromise.