Neurosurgery

The type A fracture is characterized by fractures of both the superior and inferior end plates, usually as a result of an axial load. The types B and C burst fractures involve the superior and inferior end plates, respectively. These result from an axial load coupled with a flexion load. An axial and a rotational load give rise to a type D burst fracture. The type A and D fractures appear similar on lateral-plain radiographs, but the AP view shows the differentiating rotational displacement. The incidence of neurological deficits has been reported as high as 47% in patients with this type of injury [28]. These injuries may be unstable and may need surgical stabilization, especially when there is associated injury to the posterior ligaments, the facets, the pars interarticularis or in the presence of paralysis.

There is lack of consensus for the selection of non-surgical or surgical treatment of burst fractures. However, important factors to consider before instituting treatment include the patient's neurological condition, the amount of canal compromise and the degree of angula-tion. Less than 40% canal compromise in a neu-rologically intact patient with less than 25° of kyphosis might be reasonably treated in a thoracolumbar orthotic device and allow the patient to freely ambulate. This is used for approximately 3 months, with interval lateral plain radiographs to document any progression of deformity.

In the case of greater than 40% canal compromise, greater than 25° of kyphosis and/or a neurological deficit, surgical therapy is the preferred treatment in most centers. Neurological deficits include lower extremity motor and sensory abnormalities, decreased perineal sensation and bowel and bladder dysfunction.

Any system that helps distract the injured spine segment can be used to treat burst fractures. Harrington distraction rods or the universal fixation system can be used. The Harrington distraction rods usually provide good deformity reduction, as well as long-term maintenance of the reduction. Common complications associated with their use, which has been documented to be as high as 15.5%, include dislodgement of the superior hook from the lamina and failure at the rod-hook interface [30]. Anterior decompression and fusion can be done to treat a burst fracture of a thoracic vertebral body. This can be done if the patient has an incomplete lesion, significant canal compromise, in the absence of, or minimal, kyphosis or significant comminution of the vertebral body associated with disc displacement. However, the presence of posterior column disruption may limit the effectiveness of an anterior decompression as the sole stabilization procedure.

Laminectomies are done in the setting of burst fractures for purposes of decompressing a laminar fracture or to expose a dural tear followed by posterior stabilization. As a sole procedure, a laminectomy would lead to an increase spinal instability and, potentially, worsen a pre-existing neurological deficit.

Seatbelt-type Injuries

These injuries are the result of flexion force vector acting around an anteriorly placed axis of rotation. This is seen when patients, while wearing seatbelts, as a result of the lower spine being fixed against the seat and the upper spine pivoting around an axis anterior to the spine, undergo a distraction injury to the middle and posterior spine elements. When only the osseous elements fail at a single vertebral body, this is classified as a type A injury, or commonly called a Chance fracture (Fig. 22.9) [31]. Involvement of the ligaments at the intervertebral space is called a type B injury. In a type C injury, there is failure of the two bodies and it includes the bony middle column. In the type D injury, there is also failure of the two bodies but it includes the ligament structures.

On plain radiographs, the fracture through the middle and posterior columns is usually evident. These fractures are usually unstable in flexion, although the preservation of the anterior column does not pose an emergent threat to the neural structures.

Treatment of these injuries depends on whether they are primarily osseous or ligamen-tous in nature. Osseous injuries are commonly managed with bracing devices, whereas those that are primarily ligamentous due to their unpredictability are best treated with a posterior fusion and compressive instrumentation. Decompression is rarely an issue, given that most patients do not present with neurological deficits.

Fracture Dislocation

These fractures are characterized by failure of all three columns as a result of compression,

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