9 Spine and thorax

CLASSIFICATION Injuries of the spine and thorax may be classified as follows: A-Major fractures and displacements of the thoracic or lumbar vertebrae.  Wedge compression fracture of a vertebral body  Burst fracture of a vertebral body  Distraction fracture of a vertebral body  Dislocation and fracture-dislocation B-Minor fractures of the spinal column. Fractures of transverse processes C-Fractures of the thoracic cage. Fractures of the ribs

Injuries of the vertebral bodies tend to occur from compression, flexion or twisting forces, whereas the posterior elements are more likely to be damaged by direct violence. Fractures of the thoracic cage may be relatively minor injuries, as for instance when a single rib is fractured.

A-MAJOR FRACTURES AND DISPLACEMENTS OF THE THORACIC AND LUMBAR VERTEBRAE These are the most common spinal fractures seen in clinical practice MECHANISM OF INJURY Fractures caused by vertical force acting through the long axis of the spinal column. Since the natural curve of the spine is predominantly one of flexion, the effect of such a force is to increase the flexion (Fig. 9.1). Accordingly, it is found that most vertebral fractures in the thoracic or thoraco-lumbar region are hyper flexion injuries and that fractures from hyperextension are uncommon.

In the usual flexion injury one or more of the vertebral bodies collapses anteriorly and becomes wedge shaped, giving rise to a localized kyphosis (Fig. 9.2). This is the common wedge compression fracture of a vertebral body.

Fig. 9.1 Because the main natural curve of the spine is a flexion curve, a force acting vertically from above or below will tend to increase the flexion. Nearly all fractures of the vertebral bodies in the thoracic and thoraco­lumbar regions are caused by hyperflexion or by combined flexion and rotation. Fig. 9.2 Uncomplicated wedge compression fracture of a vertebral body. The spinal cord is undamaged. The injury is caused by a flexion force. The posterior ligaments are intact, so the spine is stable.

STABLE AND UNSTABLE INJURIES it is important to distinguish between fractures and fracture dislocations in which intact posterior ligaments make the spine stable against further displacement, and those unstable injuries in which rupture of the posterior ligaments might permit further displacement, to the spinal cord or cauda equina. The distinction is fundamental for treatment, stable does not necessarily require protection whereas an unstable spine must be protected either by external support or by internal fixation.

WEDGE COMPRESSION FRACTURE OF A VERTEBRAL BODY Diagnosis In cases of major fracture there will be obvious symptoms and signs pointing to an injury of the spinal column, most commonly between the T1 and L2 vertebrae. the following features that suggest fracture: 1-Local pain 2-Prominent spinous process on palpation 3-Tenderness on percussion; and 4-Painful limitation of spinal movement. Most wedge compression fractures are inherently stable because the posterior structures are intact

Treatment The standard method of treatment may, therefore, be said to be conservative, though some prefer an interventionist approach. Standard method. The standard method of treatment in a case of moderate severity is : 1-To nurse the patient free in bed in the early stages and to concentrate entirely on restoring function. 2-Active muscle exercises, mainly for the erector spinae muscles, are begun immediately and are intensified progressively as the pain subsides. 3-The patient is allowed up as soon as pain permits (usually 1-3 weeks after the injury), and 4-Rehabilitation is continued under the supervision of a skilled physiotherapist by exercises designed both to strengthen the spinal muscles and to restore mobility.

5-Sever pain may justify the use of a thoraco-Iumbar spinal brace, which will often facilitate earlier mobilization and limit excessive flexion during the healing period. 6- Posterior stabilization and indirect reduction by distraction are usually used and will achieve some correction of deformity as well as facilitating the patient's rehabilitation. In severe fracture dislocation, 1-Fixation may be achieved by the use of posterior instrumentation using a metal Ilarlshill rectangle (Fig. 9.6) or Luque rods, which lie posteriorly and are wired to the laminae of each vertebra in the region to be stabilized. Both these devices have the disadvantage of extending over several non-affected spinal segments. 2-Recently, there has been an increasing use of pedicle screw fixation devices, consisting of shorter rods anchored by screws inserted into the vertebral bodies through the pedicles (Fig. 9.7).

Fig. 9.6 Fixation of L1/L2 dislocation by posterior rectangle held by sublaminal wiring

BURST FRACTURE OF A VERTEBRAL BODY This is a less common variant of the wedge compression fracture in which the spine is straight at the moment of injury. The intervertebral disc is forced into the affected vertebral body, causing a comminuted bursting fracture in which fragments are driven outwards in all directions. Posterior fragments may be driven into the spinal cord or cauda equina; so this injury must be regarded as much more dangerous than the simple wedge compression fracture (Fig. 9.8). In this type of injury, CT scanning or magnetic resonance scanning should be undertaken to show to what extent, if any, bone fragments are encroaching upon the spinal canal (Fig. 10.1, p. 123).

Treatment This fracture must be regarded as less stable than a simple compression fracture. If there is no neurological impairment, conservative treatment as for wedge compression fracture, but a rather longer period of recumbency is advisable. An increasing number of surgeons now tend to favor internal fixation and there are some who would advocate a decompressive operation to remove fragments that encroach on the spinal canal even in the absence of neurological deficit.

Fig. 9.8 [ A ] Radiograph and [ B ]CT scan of L1 burst fractures showing backward displacement of bony fragment into the spinal canal.

DISLOCATION AND FRACTURE-DISLOCATION These injuries are uncommon The most common displaced injury of the thoracic or lumbar spine is a fracture dislocation, in which one of the vertebrae is forced forwards upon the vertebra next below it (Figs 9.3 & 9.4) Fracture dislocation in the thoracic region or at the thoraco lumbar junction is nearly always complicated by injury to the spinal cord, and the cord injury is usually a complete transection. Fracture dislocation in the lumbar region is often complicated by injury to the cauda equina, which may be complete or incomplete.

Treatment Reduction of the displacement by posture and traction may be practicable, most surgeons would now favor operative reduction and internal fixation by Harrington rods, or pedicle screw fixation.

1-FRACTURES OF TRANSVERSE PROCESSES: These injuries are almost confined to the lumbar region. They are caused by direct violence such as a heavy blow or a fall against a hard object. (Fig. 9.10). Occasionally, there may be associated damage to the corresponding kidney or to the spleen. B-MINOR FRACTURES OF THE SPINAL COLUMN

Fig Fractures of the fourth and fifth left lumbar transverse processes.

Treatment Treatment starts with rest in bed until the acute pain subsides. At an early stage active exercises for the spinal muscles are begun and are intensified as the pain becomes less. After a few days or 1 week, according to progress, the patient begins to get up, but should continue an active programme of rehabilitation until full function has been regained.

C-FRACTURES OF THE THORACIC CAGE FRACTURES OF THE RIBS Most fractures of the ribs are caused by direct injury, as by a fall against a hard object. The fracture usually occurs near the angle of the rib. Clinical features There is severe pain made worse by deep breathing, with marked local tenderness on palpation over the site of fracture. Antero- posterior compression of the thorax by springing the ribs also causes pain at the site of fracture. The diagnosis is confirmed by radiography.

Treatment Fractures of the ribs unite spontaneously, Breathing exercises should be encouraged to ensure that the lung is fully expanded. In severe cases pain may be relieved by injecting a solution of long acting local anaesthetic about the site of fracture. Complications The complications include hemothorax, pneumothorax, surgical emphysema and pneumonia.