IS A SPINAL INJURY UNSTABLE?

Take the patient to the X-ray room yourself. If possible X–ray him without moving him. If he has to be moved, supervise how this is done. An inexperienced X–ray assistant can make a par-tial cord lesion into a complete one.

Take one good AP view and two lateral views with the patient lying, one lateral view centred over his vertebral bodies at the site of maximal pain and tenderness, and another over his spinous processes at this level. Also take an open mouth view. You must see his whole cervical spine, so make sure his shoulders are well pulled down. Lesions at C6–C7 and C7–T1 are often missed. Don’t try to take oblique views; they are difficult to take and interpret.

If possible, take a ’swimmers view’; this requires considerable experience and ability. Count the vertebrae in the lateral view to make sure that you have not missed C7. If necessary, take another view with traction to the patient’s arm. You will see C7 and perhaps the upper border of T1.

As always with difficult films, sit down and look at them on a viewing box, or with an electric light bulb, while you have no other distractions. Start at the extreme edges of the film, and work in towards the middle. It is quite common for the injury to be at the edge of the film. Use the signs which follow and Fig. 64-8 as a check list.

AP VIEWS OF AN INJURED CERVICAL SPINE

In the following section the numbers in brackets refer to Fig. 64-8.

Are any vertebral bodies displaced (1)?

If they are, the injury may be unstable.

Are any spinous processes out of line (2)?

A rotational injury can twist them out of line, especially in the cervical spine, even though the vertebral bodies themselves are still inline. If they are out of line, the injury is probably unstable.

Are the pedicles on either side of the spinal canal displaced laterally out of the line, compared with those above or below (3)?

If they are, the injury is probably unstable. The vertebral arch forms a ring, so if part of the ring is to displace, has to fracture in two places. Either both pedicles are displaced, or neither of them.

Are the transverse processes of the patient’s lumbar vertebrae broken (4)?

If they are, they make no difference to his spine, but suspect that his abdominal organs may be injured, especially his kidneys, and that he may have a retroperitoneal haemorrhage.

LATERAL VIEWS OF AN INJURED CERVICAL SPINE

Take a good lateral film at the level of the lesion. Examine he vertebral bodies from top to bottom, they should have a normal box–like appearance.

Is the body of a vertebra wedge shaped? (5)

If so, the patient has a compression fracture. These fractures are usually stable, so, if there are no other signs which indicate instability, diagnose a stable injury confidently.

Has the body of a vertebra broken into many fragments (6)?

If so, he has a burst fracture. This is more likely to be unstable and to have injured his spinal cord than a wedge fracture.

Has one vertebra slipped forwards on another (7)?

This is a serious sign of instability, particularly in the cervical region. It usually shows that the posterior longitudinal ligament has ruptured, perhaps with dislocation of the articular facets, or with fractures of the laminae and pedicles. The patient’s posterior intervertebral joints may have subluxed or dislocated on one or both sides. If displacement is equal to half the vertebral body, one intervertebral joint has probably dislocated.

Do the posterior margins of all the vertebral bodies form a smooth curve?

They should be smooth and continuous. Any abrupt change or step is a sign of subluxation and instability. Regard the odontoid as a vertebral body.

Is the space between the vertebral spines unequal?

They may be widely separated at the site of the injury. If so, the injury is probably unstable.

Have any of the spinous process broken at the base, so that they are lying free? Have any of the articular facets fractured?

These are difficult to see, and both indicate instability. If there is a sharp angulation with widening of the spinous processes, this suggests an unstable injury.

Does a facet on an upper vertebra lie in front of the facet of a lower one?

If it does, the facets are locked. Unilateral locked facets are difficult to be certain about, they are easier when they are bilateral. They are very rare indeed outside the cervical region. Locked facets, especially if they are bilateral, are not necessarily unstable.

Are the articular facets displaced?

The first two facets in the cervical region are easily seen, but the third needs a very good X–ray.

Special signs in the lateral view in the cervical region.

Examine the gap between the back of the patient’s pharynx and the front of his vertebral bodies. Soft tissue swelling here suggests that he may have a spinal injury, probably an unstable one. Study every lateral view of the cervical spine you see carefully, so that you know what the normal soft tissue shadow looks like.

Look carefully at the base of the patient’s odontoid, and at the arch of his atlas.

OTHER FINDINGS Fractures of the spinous and transverse processes are unimportant—they are essentially muscle injuries.

LATERAL VIEWS IN FLEXION AND EXTENSION

INDICATIONS These views are only indicated if you suspect a high fracture of a patient’s neck, and the standard AP and lateral views, and an AP view through his mouth are normal. Some surgeons consider these much too difficult for most of our readers.

CAUTION! (1) The manoeuvres necessary to take these views may be dangerous in acute lesions. (2) The patient must be conscious. (3) Always be present yourself when these views are taken, do them gently, and stop immediately if he has arm or leg symptoms.

Carefully flex his neck and take a film, then carefully extend his neck and take another one. Look for abnormal movement of one vertebra on another. In a flexion view look for the vertebral bodies slipping forwards over one another. In an extension view look for an abnormal gap between the front of two vertebral bodies, or for a posterior dislocation.

ATLAS AND AXIS See Section 64.8.

DIAGNOSTIC DIFFICULTIES W ITH INJURIES OF THE CERVICAL SPINE

If you SUSPECT AN INJURY CLINICALLY BUT CANNOT SEE ONE IN THE FILMS, take more films higher up the spine. This is especially important if there are signs that the cord has been injured.

A NORMAL X–RAY DOES NOT NECESSARILY MEAN A STABLE SPINE