Thoracic and lumbar injuries

Thoracic and lumbar injuries

Thoracic and lumbar injuries

The thoracic spine is often demonstrated well on the anteroposterior chest radiograph that forms part of the standard series of views requested in major trauma. This x ray may be the first to reveal an injury to the thoracic spine. Radiographs of the thoracic and lumbar spine must be specifically requested if a cervical spine injury has been sustained (because of the frequency with which injuries at more than one level coexist) or if signs of thoracic or lumbar trauma are detected when the patient is log rolled. In obtunded patients in whom the thoracic and lumbar spine cannot be evaluated clinically, the radiographs should be obtained routinely during the secondary survey or on admission to hospital. Unstable fractures of the pelvis are often associated with injuries to the lumbar spine.

Patient with fracture of T5 with widening of mediastinum due to a prevertebral haematoma, initially diagnosed as traumatic dissection of the aorta, for which he underwent aortography.

The three (anterior, middle and posterior) spinal columns.

A significant force is normally required to damage the thoracic, lumbar, and sacral segments of the spinal cord, and the skeletal injury is usually evident on the standard anteroposterior and horizontal beam lateral radiographs. Burst fractures, and fractures affecting the posterior facet joints or pedicles, are unstable and more easily seen on the lateral radiograph. Instability requires at least two of the three columns of the spine to be disrupted. In simple wedge fractures, only the anterior column is disrupted and the injury remains stable. The demonstration of detail in the thoracic spine can be extremely difficult, particularly in the upper four vertebrae, and computed tomography (CT) is often required for better definition. Instability in thoracic spinal injuries may also be caused by sternal or bilateral rib fractures, as the anterior splinting effect of these structures will be lost.

A particular type of fracture, the Chance fracture, is typically found in the upper lumbar vertebrae. It runs transversely through the vertebral body and usually results from a shearing force exerted by the lap component of a seat belt during severe deceleration injury. These fractures are often associated with intra-abdominal or retroperitoneal injuries.

A haematoma in the posterior mediastinum is often seen around the thoracic fracture site, particularly in the anteroposterior view of the spine and sometimes on the chest radiograph requested in the primary survey. If there is any suspicion that these appearances might be due to traumatic aortic dissection, an arch aortogram will be required.

Left: lateral radiograph of lumbar spine showing burst fracture of L4 in a patient with a cauda equina lesion. Right: CT scan shows the fracture of L4 more clearly, with severe narrowing of the spinal canal.

MRI showing transection of the spinal cord associated with a fracture of T4.

Fractures in the thoracic and lumbar spine are often complex and inadequately shown on plain films. CT demonstrates bony detail more accurately. MRI is used to demonstrate the extent of cord and soft tissue damage.

Indications for thoracic and lumbar radiographs:

Major trauma
Impaired consciousness
Distracting injury
Physical signs of thoracic or lumbar trauma
Pelvic fractures
Altered peripheral neurology

Left: CT scan with (right) sagittal reconstruction showing C7–T1 bilateral facet dislocation — a useful technique at the cervicothoracic junction.

Chance fracture of L4 in a 17-year-old back-seat passenger, wearing a lap seat belt. There is a horizontal fracture of the upper part of the vertebral body extending into the posterior elements. There is also wedging of the body of L4 and more minor wedging of L5.