Spinal injuries are a relatively common Orthopedic problem. 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 mostly 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 configuration of the fracture of the spine depends upon how and where the injuring force was applied to the spine during the accident and can be quite complex. When analysing any particular fracture the injuring force must be analysed as to whether the force was applied in any one or a combination of the following directions:
- Whether the force served to compress or distract the spine.
- Whether the force served to bend the spine to the front, the back, or the side.
- Whether the force served to rotate the spine to the right or the left.
- Whether there is a shear force on the spine.
The different regions of the spine – cervical, thoracic, lumbar, sacrum and coccyx – have different properties in shape and strength from each other which will affect how and where the spine will mechanically fail in response to any particular force.
The predominant symptom which an individual suffering a fracture of the spine 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 spinal cord, in the adult, is carried through the spinal canal of the cervical and thoracic vertebrae so it is with injuries to these portions of the spine that there may be significant neurological damage in association with an injury. In the lumbar spine, in the adult, the spinal cord has divided into numerous individual branches; in which case the neurological damage associated with a fracture in this region may not be so great as an injury higher up the spine.
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 fracture or dislocation of the spine until it the 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 it can result in paraplegia or quadriplegia.
It is standard practice to reduce dislocations of the spine and then fixate them (hold them in the correct position) by traction, bracing or internal fixation until they are healed.
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.
Simple traction can be applied, either as a temporary or long term treatment of a fracture of the neck, through callipers inserted into the skull.
In some instances an ‘external fixation’ device, such as ‘halo traction’ is used. This is a device which is most commonly used when there are fractures of the neck. 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, particularly when there is associated neurological injury, they may be repositioned operatively and held by means of a suitable internal fixation device. These devices include various forms of pins, rods, cages and plates and screws, inserted from the front or from the back. Use of these devices, if indicated, will generally allow early discharge of the injured person from hospital and rapid re-integration back into his or her society. These procedures do, however, have some disadvantages inasmuch as there is a small risk of an operative complication ensuing, including infection, misplacement of the implants, or nerve damage.
SPECIFIC HIGH VELOCITY INJURIES OF THE SPINE
Fractures and Dislocations of the Cervical Spine
The cervical spine is divided, anatomically and functionally, into two regions – the upper cervical spine (occipital bone, C1 and C2) and lower cervical spine (C3 – C7). The lower region supports the head and neck, while the upper region both supports the head and allows for its movement.
Fractures of the occipital condyle
The result of high energy injury trauma, often sporting or automobile injuries. These injuries are often difficult to diagnose. The pain in the neck is often non-specific and the bony injuries sometimes cannot be visualised with plain radiographs and require a CAT scan for their demonstration. They are sometimes complicated by injury to the brain stem and lower cranial nerves. The surgical approaches are difficult and fraught with danger. Conservative treatment usually produces a satisfactory result.
Fractures of the Atlas bone (C1)
The Atlas is ring-shaped bone with a condyle on either side which articulates with the occipital condyles. It is generally fractured by forceful vertical compression, causing both its anterior and posterior arch to break and the two condyles to separate. In addition the inner transverse ligament may also rupture. Treatment is usually prolonged immobilisation and traction unless the transverse ligament in his damaged, making it very unstable, in which case surgical stabilisation is indicated.
Fracture of the Dens
The dens is the small bony 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.
Traumatic spondylolisthesis of C2 (hangman’s fracture)
Associated with forceful flexion extension of the neck, resulting in fractures of the pedicle of C2 and varying degrees of dislocation of C2 on C3. Fractures with minor degrees of displacement are generally treated with reduction and prolonged immobilisation whereas those with frank displacement, indicating instability, are usually treated by internal fixation.
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. In all these cases the neck is very unstable and surgical stabilisation of the injury is required.
High Energy Fractures of the Thoracic Spine
The thoracic spine lies between the cervical spine and the lumbar spine and consists of 12 vertebrae – T1 to T12. Posteriorly this spine gives origin to the ribs which are joined to the sternum anteriorly. The movements of the thoracic spine are limited, due both to the shape its vertebrae and to the shape and to the attachments of the ribs which give it further support. This combination provides a slightly expandable cavity which contains and protects the heart and lungs, and contributes to their physiological function.
In order to guide treatment, the fractures of the Thoracic (and Lumber) spine is assessed for its stability. This is generally done according to a schema proposed by Denis, in which the injury to the damaged vertebra, as seen on the radiographs and scans, is divided into three columns as follows:
- An anterior column, comprising the anterior half of the vertebral body as well as the anterior longitudinal ligament and the anterior portion of the disc.
- A middle column, made up of the the posterior half of the vertebral body, the posterior disc and the posterior longitudinal ligament.
- A posterior column, consisting of the posterior bony elements and ligaments.
When only one column is affected the fracture is considered to be stable and when two of the three columns are disrupted the fracture is considered unstable. It must be noted that if any neurological damage is evident, the fracture is assessed as being ‘unstable’. These assessments are then often used as a guide to treatment. Whatever the assessment, a mainstay of treatment is pain control with an appropriate analgesic preparation and further treatment is given with a view to early mobilization and rehabilitation.
Many of the thoracic spine fractures assessed as ‘stable’ can be treated with analgesics and, perhaps with a simple spinal brace. It is a bit more difficult to treat an ‘unstable’ fracture with a brace where two columns have been involved, particularly if the fracture lies in the upper thoracic spine when a very long and cumbersome orthosis is required. For most ‘unstable’ fractures some form of operative stabilization, anterior or posterior, must be considered.
High Energy Fractures of the Lumbar Spine
Injuries to the lumbar spine are caused by similar forces to those which damage the thoracic spine and are assessed and managed in much the same way. Guidance for their management is similarly influenced by using Denis’s classification and, according to the configuration of the fracture and/or dislocation, can be treated conservatively or by surgery.
A significant difference between these two areas of the spinal column is that the lumbar spine has a lot movement than both the thoracic spine and the sacrum, which lie at either end. What this means is that any force, acting to injure the spine, is more likely to do so in the region of its junction with the thoracic spine (T12/L1) and with the sacrum (L5/S1) as the forces will centre on these regions.
Injuries to the sacrum and pelvis
The sacrum is a large block of bone which provides the foundation for the bony pelvic ring and the spine which ascends from it. In itself the sacrum is very strong and usually requires a lot of energy applied directly to it in order for it to be fractured. Accordingly isolated high energy fractures of the sacrum itself are relatively uncommon, the injuring forces more commonly causing sacro-pelvic injuries.
The significant feature of injuries in this region is that fractures of the pelvis and sacrum are often associated with severe soft tissue injuries. Blood loss can be massive. The pelvic viscera (bowel, bladder, urethra and vagina) can be severely torn. Likewise there can be injuries to the nerves lying within the pelvis. With these injuries resuscitation is of paramount importance and treatment of the visceral injuries may take preference over those of the bone.
Sacro-pelvic fractures and dislocations.
The sacrum and pelvis, together, form a strong ring of bone. The sacrum articulates with the pelvis on both its sides by large, flat joints which are held together by thick fibrous ligaments. For these joints to be injured it requires that there is an additional fracture or dislocation of the pelvic bones. The sacro-pelvic ligaments can be damaged in two ways.
- There may be an ‘open book’ type of injury where a pelvic bone is fractured or there is a diastasis (rupture) of the pubic symphysis which ‘breaks the ring’ and allows the sacro-pelvic joint to spay out like an open book. This lesion used to be treated with a pelvic sling while the person was confined to bed. Nowadays an anterior external fixator can be effective in holding the ring closed until the injuries have healed. Alternatively surgical plating of the pelvic fracture can be sufficient.
- There may be a vertical ‘shear’ fracture of the sacro-pelvic joint in which there is a vertical displacement of one of the pelvic bones. In this case the joint dislocation or fracture has to be reduced and held with screws, as well as treating the associated pelvic fracture.
Fractures of the pelvis
Minimally displaced fractures of the pelvic ‘rami’, simple diastasis of the pubic symphysis, or fractures of the large iliac blades on either side of the pelvis can often be treated conservatively, with or without a pelvic sling and crutches. Larger or more comminuted (fragmented) fractures are often treated with reduction and internal fixation with screws, plates and pins. The caveat with regard to blood loss and visceral injuries remains.
Fractures of the acetabulum are severe injuries, sometimes associated with injury to the sciatic nerve. Occasionally these can be treated using traction to the femur but more often require open reduction and fixation using malleable steel plates.
Fractures of the coccyx (coccydynia)
The coccyx (or tailbone) is a series of 3 to 5 small bones attached to the lower end of the sacrum. It occasionally is injured, usually as the result of a fall onto the buttocks or during childbirth, when one of the bones is fractured or one of the joints dislocated. This injury can prove troublesome as it causes pain in the buttock when sitting or lying down. If treated early enough a dislocation of the coccyx can occasionally be reduced. More often or not this is not possible. The pain from the coccyx often settles down by itself, if given enough time; particularly with the use of a ring-cushion. If this is not successful an injection of a steroid solution into the coccyx is sometimes very helpful. If all else fails the last resort is for the injured section of the coccyx to be removed.