Spinal Fracture
Although the spine is mobile it is, in the young individual, a very strong structure and it generally takes a lot of force to damage it. Nevertheless, high velocity injuries such as motor vehicle accidents or falls from a height can subject the spine to excessively high forces which crush its vertebrae or tear its ligaments and discs. These injuries generally occur where the spine is most mobile; in the cervical spine in the neck and around the junction of the thoracic and lumbar portions of the spine.
The predominant symptom which an individual involved in such an event will experience is pain in the affected region of the back. The spine is responsible for protecting the spinal cord which carries the nerves which pass down from the brain to and from the limbs. In the event of an injury to the spine the spinal cord may also be damaged, although the occurrence of this complication is relatively low considering the number of spinal injuries which occur.
The management of a significant spinal injury will be governed to some extent by the region of the spine which has been injured, the nature of the spinal injury, and whether or not there has been damage to the spinal cord. The basic principles of treatment are:
• To reduce and hold the spine until it the fracture or dislocation has healed.
• To manage any injuries to the nerves on the merit of the damage which they have sustained. Damage to the spinal cord is of major significance in cases of spinal injury as they can result in paraplegia or quadriplegia.
Minor fractures of the spine can often safely be treated with bed rest for a period and then progressive mobilisation, usually with the aid of a spinal support or brace.
In some instances an ‘external fixator’ device is used. This is a device which is most commonly used when there are fractures of the cervical spine. It is supported on the shoulders and passes up the sides of the neck to hold the head by temporary pins passing into the outer portion of the skull. This apparatus allows positioning of the injured portion of the cervical spine and holds it rigidly until it has healed.
Where there is significant displacement or instability of the damaged vertebrae they may be repositioned operatively and held by means of a suitable fixation device. These devices include various forms of pins, rods, plates and screws. Their main disadvantage is that there is a small risk of an operative complication ensuing, such as infection, misplacement of the implants, or nerve damage to some extent. On the other hand, use of these devices, if indicated, will generally allow early discharge of the injured person from hospital and rapid re-integration with his society.
OSTEOPOROTIC FRACTURES OF THE SPINE
As people get older there is a tendency for the bones to become weaker, particularly in women. The vertebrae of the spine are not exempt from this process and, if it occurs, they are susceptible to fracturing as are osteoporotic bones in other parts of the skeleton.
Vertebral fractures can present in one of two ways in the elderly person:
• The spine slowly becomes shorter as the vertebrae gradually collapse and subside as a result of continual, recurrent ‘micro fractures’. These are tiny fractures of the individual trabeculae making up the vertebra which heal after some displacement. There occurrences typically give rise to an constant, dull ache in the back for which no other significant cause can be demonstrated. For this condition the standard treatments for osteopaenia is usually of benefit.
• If the elderly person trips or sustains a sudden fall this relatively minor event may be sufficient to cause one of the vertebrae to collapse under the sudden strain on the spine. In this instance a compression fracture of the spine will be demonstrated on x-ray. If the displacement is small a period of rest followed by a temporary spinal support and medical treatment of the osteoporosis is usually sufficient. If, however, the pain is severe and prolonged the individual may benefit from stabilisation of the fracture. This can be done in one of two ways.
Vertebroplasty
A method initially devised to manage these particular fractures is termed ‘vertebroplasty’. This technique consists of injecting a 'cement' through two small needle tracts into the collapsed vertebra. This substance hardens within the broken bone and supports it, reducing the pain experienced by the individual.
Kyphoplasty
An enhancement of the vertebroplasty technique has been developed whereby not only is the fractured vertebra stabilised but an attempt is made to restore its height and shape by expanding two small balloons inside it, before injecting the supporting substance. This method corrects the abnormal angulation of the spine and is called 'kyphoplasty'; a kyphus being the term for the deformity of the spine which develops after such a fracture. In addition to reducing the pain from such an injury, this technique attempts to restore the alignment of the spine and thus maintain its normal biomechanics and reduce the chance of further such fractures from occurring. This technique is also a useful way of treating some fractures of the spine due to malignant disease.
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PECIFIC FRACTURES OF THE SPINE
Fracture of the Dens
The dens is the small peg arising from the front of the 2nd cervical vertebra which allows the head to turn from side to side through a relatively large range of motion. It typically gets damaged when the head is forcibly and severely moved forward or backward during motor vehicle accidents or during a fall.
The Dens usually fractures in one of three places - at its tip, in the middle of the body, or at its base. The fracture through the base generally heals well with external support but the fracture through the body has a tendency to heal only with a fibrous union, particularly if displaced. For this reason internal stabilisation of these fractures may be the best course.
Dissociations in the upper cervical spine
Great force is required to bring about a dissociation between the upper cervical vertebrae and they generally only occur as a result of a motor vehicle accident or other such major injury. They are relatively uncommon, which is perhaps fortunate as they are frequently fatal. In those who do survive this injury neurological injury is often seen, in some cases the cranial nerves being affected. (Lower cranial nerve palsies - potentially lethal in association with upper cervical fracture dislocations - Hammer AJ Clin Orthopedics 266 : 64 - 69.) In all these cases the neck is very unstable and surgical stabilisation of the injury is required.
