Follwing xrays are of thoracolumbar spine of patient with spinal injury. The patient has fracture of D12 vertebra and dislocation of D11 over D12 vertebra.

Here is the AP view

Fracture of D12 Vertebra With Dislocation of D11-D12 AP View

Here is lateral view

Lateral View Of Same Injury

Associated history with the image was not available.

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Xray showing Cervical Diislocation C4 Over C5 Vertebra

MRI shows the dislocation and a disc compressing on the cord as well.

MRI Showing Dislocation C4-C5 and intervertebral Disc Compressing The Cord

Such patients often present with weakness of all the four limba following the injury.

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THe xray showed C4-C5 dislocation and MRI revealed a compression on the cord by disc between these two vertebrae.

Here is MRI picture.

The patient was treated by anterior decompression and fusion of C4 and C5 vertebrae

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CT Scan of Spine Showing D12 Vertebra Fracture

The patient had this fracture due to fall from height.

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Nonsurgical Complications

These complications are not related to surgical procedures and in most cases are related to injury pattern.

Neurological Deficits

Neural deficit is quite a significant problem associated with thoracolumbar injuries. While early neural deficits are following injury to the cord, delayed deficits can be due to  syrinx formation after thoracolumbar trauma.

Deformity

Deformity could be either acute or it could be progressive in nature. Increased kyphosis or malalignment has been a problem with non operative treatment. Surgery can provide the benefit of alignment but long term results are similar when pain and function are assessed.

Kyphotic deformities greater than 30 degrees are known to have risk of progression of pain and should be considered for operative intervention.

Dural Tears

These are particularly associated with vertical lamina and facet fractures and often suggest likelihood of  nerve root entrapment. In cases who are managed operatively, a repair should be attempted. Persistent leaks may require placement of subarachnoid drain.

If nerve root entrapment is suspected an exploration may be carried.

Visceral Complications

Ileus or decrease in bowel movements can occur in these injuries and should be looked for because a suspicion of ileus warrants aggressive workup and treatment. Thracolumbar injuries are also associated with increase  peptic ulceration.

A non functional bladder following spinal cord injury is prone to infection and should be cared for.

Surgical Complications

There are considerable risks inherent in spinal surgery.
Neurological Deficit

There are risks of further neurologic injury during the operative process. It may occur during transfer of the patient, retracting the spinal cord or nerve roots, during instrumentation or due to postoperative epidural hematoma. In a patient with intact or incomplete neurologic status.

Bleeding & Dural Tears

Spine surgery includes blood loss and may not be tolerated by patients under physiologic stress. Coagulopathy [A defect in the mechanism of blood clotting]  can be a major problem in the trauma patient. All patients of spine surgery need to have blood group cross matching and saving of blood units in case the need arises.

Intraoperative iatrogenic dural tears undoubtedly occur during the surgical care of these patients and theses should be treated by repair, if possible.

Infection

Infection is a major concern and if present should be dealt with aggressively.

Implant Failure

Metal breakage, screw pullout, or subsidence may occur during the postoperative period, leading to at least a partial loss of correction.

Pulmonary & Vascular Complications

Pneumothorax, erosion into the great vessels following instrumentation, injury to the iliac vessels, ureter, and sympathetic plexus have been reported

Pseudarthrosis

Failure of fusion of vertebrae can lead to formation of psudoarthrosis or false joint  in approximately 4% of cases following surgery for thoracolumbar trauma. Chronic pain and  worsening deformity.

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These osteoporotic compression fractures are  occasionally accompanied by radicular pain and rarely by neurologic deficit.

Presentation

Most of the patients are quite elderly. The  usual presentation is of severe back pain which can be often accompanied radiating pain. Neural deficit is rare.

Investigations

Blood investigations could be normal or may suggest other geriatric comorbidities. Xrays is the basic investigation and often only required image investigation. CT and MRI are usually not required in diagnosing  osteoprotic fractures but to rule out  some other pathology like malignancy.

Treatment

Most of these fractures get better by analgesic medication and rest. Bracing can be given but is not well tolerated in elderly patients who sustain these injuries.

In situations where there is a significant neurologic deficit, disabling deformity, or marked pain, surgery can be a reasonable option.

Vertebroplasty or kyphoplasty are techniques that have been tried with variable success rate.

Open surgery is reserved for patients with neurologic deficits or intractable pain associated with a severe spinal deformity.

Posterior segmental instrumentation, usually with pedicle screws, is often performed to supplement anterior surgery in osteoporotic patients with more significant thoracolumbar trauma.

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Here a missile passes through the spine rather than the spine being forcibly accelerated or decelerated that results in structural failure.

The extent and type of neurologic deficits from gunshot injuries to the thoracolumbar spine vary.

A complete neurological deficit is  more common than incomplete deficits in these injuries.  Neural injury occurs due to blast effect in which the bullet’s energy is absorbed and transmitted to the soft tissues.

The fractures associated with low-velocity gunshot wounds are generally stable fractures. Most of these cases have a low infection rate but transintestinal gunshot wounds, where the bullet passes through the colon, intestine, or stomach before passing through the spine carry a significantly higher rate of infection.

High-energy wounds, as caused by a rifle or military assault weapon, require open debridement and stabilization.

In most of these injuries, decompression is rarely indicated.

One exception is when a bullet fragment is found in the spinal canal between the level of T12 and L5 in the presence of a neurologic deficit.

Delayed bullet extraction is rarely indicated for lead toxicity or late neurologic deficits due to migration of a bullet fragment.

These patients are initially best treated with an orthosis. If the follow up xrays show progression of deformity or signs of instability, decisions to perform a surgery might be considered.

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By definition, fracture-dislocation are three column injuries. The mechanism of injury usually involves a combination of forces, including flexion, extension, shear, torsion, and compression.

These injuries are also associated with other musculoskeletal and visceral injuries often.

Fracture dislocations are caused by hyperflexion and rotation forces. One of the example is when a patient is ejected from a vehicle at high speed.

Evaluation of the patient is done in the same manner for any spinal injury. But here a few precautions are very important.

Because these injuries are highly unstable, even the neurologically intact patient must be carefully protected during any necessary testing or emergent operative procedures.

Investigations

Xrays would reveal the pattern and severity of the injury. On lateral views,  a translational deformity or listhesis at the site of injury is visible. The facets are fractured due to substantial translational or rotational forces and displacement may be appreciated on both AP and lateral x-rays. MRI would delineate neurological injury in detail.  CT scanning and reconstruction sequences are very important in characterizing these injuries more accurately.

Treatment

As fracture dislocation injuries to the spine are quite unstable injuries, these are mostly treated with decompression and surgical stabilization. Even in neurologically intact patients surgery is indicated so as the risk of further damage by unstable spine is nulled. Direct decompression is indicated for those patients with an incomplete injury and hopes of improvement.

In case of complete cord injury, stabilization is indicated for the purpose of rehabilitation.

Nonoperative Treatment

Rarely, when the patient is not fit for surgical treatment or is not willing to for surgery, reduction can be attempted through postural manipulation.  Nonoperative treatment requires an extended period of bracing and bed rest.

Operative Treatment

Posterior surgery is usually most useful for achieving reduction and stability after these injuries.  The surgery involves fracture reduction, decompression, fixation with pedicle screws and fusion of the vertebrae.
Because of the severe ligamentous disruption and gross instability that occurs, long fusions have been advocated.

If the spinal stability is restored, the patient can be mobilized as required to improve pulmonary function and general medical care. External immobilization or bracing is usually not necessary but may be given on individual basis.

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The classic mechanism involves the patient being thrown forward across an intact lap-belt, resulting in a hyperflexion force acting around a center of rotation anterior to the spinal column at the belt.

This results in distraction forces at all three columns of the spine

• The posterior elements are torn apart through either the facet joints or the bone itself
• The middle column is torn apart through either the posterior disc or the posterior vertebral body
• The anterior column is either disrupted in severe injuries or left as a hinge that cannot resist either flexion or rotational displacement

There could be associated injuries frequently due to violent compression of viscera between the spinal column and lap belt. Rates of intra-abdominal hollow viscus injury is reported as high as  50%.

Flexion distraction injuries can be either single level or two level.

Single-level injuries

This kind of injury passes through the posterior ligamentous structures and the underlying disc at the same level, or through the posterior lamina, pedicle, and vertebral body in the same transverse plane. These injuries disrupt only a single motion segment.

Two-level injuries

These injuries begin posteriorly at one level of lamina or facet joint, then proceed anteriorly in an oblique fashion so that the injury passes out of the vertebral body into an adjacent disc or through the disc into an adjacent body. In these injuries, two adjacent motion segments are disrupted, and stabilization requires addressing both levels of injury.

With most car manufacturers today providing  lap-shoulder belts as standard equipment, there is a  lower incidence of flexion-distraction injuries.

Investigations

Xrays are the basic investigations. Computed tomography and MRI are used for better delineation of fractures and to know the health of the spinal cord. In case of surgery preoperative CT or MRI images can be used to find whether pedicles of the injured vertebra are intact or not.

Nonoperative Treatment
There is very little role of non operative treatment in these injuries. One of the rare indication is a  reducible fracture through the bone. In this situation, the fracture can be reduced and maintained in a brace or cast. Reduction is performed by applying hyperextension forces to the spinal column and this is followed by casting or bracing in hyperextension.

Patient should be followed up with serial xrays to ensure maintenance of the reduction. External immobilization is recommended for a minimum of 3 months.

Surgical Treatment

If the injury is ligamentous or osseoligamentous [involves bone and ligament], surgical stabilization is indicated. The primary goal of surgery in flexion-distraction injuries is restoration of alignment and stability rather than decompression. In cases where direct neural compression from a herniated disc or hematoma  is responsible for the neurological deficit, decompression becomes an important objective.

In most cases, flexion-distraction injuries involve disruption of the posterior intervertebral disc and the posterior ligaments, but leave the anterior longitudnal and anterior annulus intact.

Therefore posterior reduction and compressive stabilization is usually sufficient.

As anterior column is not destabilized, doing an anterior surgery in flexion distraction injuries is not a good idea  as it would lead to greater destabilization.

The surgery  usually done is decompression, reduction of the fracture, fixation with pedicle screw system and  posterior segment fusion.

After the surgery, an orthosis like Thoraco lumbo sacral orthosis [TLSO] is used for 8 to 12 weeks. Flexion extension x-rays are done to check the motion at area of attempted spinal fusion, if any.

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2. Descriptive Classification Of Thoraco Lumbar Spine Injuries
3. Fracture Dislocations In Thoraco Lumbar Spine

Earlier Chance fracture was treated as a separate entity but modern text books use the term flexion distraction injuries and chance fractures as synonyms. I think the term Flexion Distraction Injuries is more descriptive and should be used while other should be dropped.

Mcfee et al in their mechanism of injury listed both the injuries and their mechanisms

Chance fractures are horizontal avulsion injuries of the vertebral bodies caused by flexion around an axis anterior to the anterior longitudinal ligament. The entire vertebra is pulled apart by a strong tensile force.

In flexion distraction injuries, the flexion axis is posterior to the anterior longitudinal ligament. The anterior column fails in compression, whereas the middle and posterior columns fail in tension. This injury is unstable because the ligamentum flavum, interspinous ligaments, and supraspinous ligaments usually are disrupted.

It must be noted that, despite their name, most of the flexion distraction injuries do not occur from a pure flexion-distraction mechanism.

A component of vertebral body compression or lateral translation may be noted in many cases, suggesting that the center of rotation was probably not anterior to the spine.

The characteristic feature of a flexion-distraction injury is primarily tensile failure of the posterior ligamentous complex, facet capsules, and intervertebral disc or bone itself. Injuries rarely occur through bone alone and are most commonly the result of osseous and ligamentous failure.

The term Chance fracture was used to denote  horizontal avulsion injuries of the vertebral bodies where the  entire vertebra is pulled apart by a strong tensile force.

Chance fracture represents a pure bony injury extending from posterior to anterior through the spinous process, pedicles, and vertebral body, respectively and in its true original sense, it is quiet rare now.

A Typical Chance Fracture, Reconstructed CT image

History

The Chance fracture was first described by G.Q. Chance in 1948, a fracture caused horizontal splitting of the vertebra that begun with the spinous process or lamina and extended anteriorly through the pedicles and vertebral body. The vertebral body tends to have a wedge compression fracture and the posterior elements of the vertebra were distracted. These fractures most commonly occured at the T12, L1, or L2 level and were stable in site of the injury.

Chance fractures later became known as “seat-belt fractures” or “seat-belt injuries” as it was the most common cause after the advent of lap seat belts in cars. A head-on collision would cause the passenger wearing a lap-belt to suddenly be flexed at the waist, thus creating tremendous stress on the posterior elements of the vertebra.

Most of the vehicles now have combination of shoulder and lap belts. With this switch Chance fractures have become less associated with automobile injuries. Most Chance fractures now result from falls or crush type injuries where the thorax is acutely hyperflexed.

Image credit:http://www.e-radiography.net/radpath/f/chance_fracture.htm

Related posts:

1. Flexion Distraction Injuries of Thoraco Lumbar Spine
2. Descriptive Classification Of Thoraco Lumbar Spine Injuries
3. Fracture of C1 Vertebra or Atlas