The bony injury may comprise either a fracture or a dislocation or a combination of both (fracture disloca- tion). The most important consideration is the stability of the fracture. A stable fracture is one that is unlikely to undergo further displacement or neurological damage;
an unstable fracture may undergo further displace- ment with the risk of further neurological damage.
Assessing stability
The assessment of stability is fundamental to the ini- tial management of the patient. It depends upon the
integrity of the structures that make up the normal spinal column, namely the vertebrae, intervertebral discs and ligaments. While it is relatively easy to de- termine stability in upper cervical fractures, it is less easy in lower fractures such as those in the thora- columbar region. To overcome this, the concept of the three-column spine is useful (Figure 16.2).
The three columns are made up as follows.
• The anterior column comprises the anterior lon- gitudinal ligament, anterior parts of the vertebral body, disc and annulus fibrosus.
• The middle column comprises the posterior parts of the vertebral body, disc and annulus fibrosus, and the posterior longitudinal ligament.
• The posterior column comprises the facet joints, the posterior arch and the intervening ligament com- plex, itself comprising supraspinous ligaments, in- terspinous ligaments and ligamentum flavum.
Disruption of two or all of these columns results in spinal instability. Disruption of a single column, such as in a wedge fracture affecting the anterior half of the vertebral body, is a stable injury without risk of further displacement or further neurological damage.
Types of fracture
Most fractures are caused by a sudden hyperextension or hyperflexion, often combined with compression or distraction. The results of such forces may be con- sidered in terms of five distinct levels in the spine.
1 Upper cervical spine (C1, C2). In the upper cervi- cal spine, flexion/extension injuries may result in fracture of the dens (odontoid process) at its base,
Spina bifida occulta Meningocele Myelomeningocele
Figure 16.1 Spina bifida.
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The spineatlantoaxial dislocation or fracture of the atlas or axis (hangman’s fracture). The spinal canal is wide in the upper cervical region and immediate spinal cord damage may be minor, although, in more se- vere injuries, fatal damage to the cord may occur.
2 Lower cervical spine (C3–C7).
a Hyperflexion injuries may result in anterior dislocation of facet joints, with consequent narrowing of the spinal canal and neurologi- cal injury. A corresponding step may be seen on a lateral cervical spine X-ray. Either one or both facet joints may be involved. Because of the much closer fit of the cervical cord within the vertebral canal compared with the wider lumbar region, the incidence of cord damage in these injuries is extremely high, with result- ant tetraplegia or paraplegia. If the facet joints do not lock, there may be spontaneous reduc- tion and little to see on a lateral X-ray, although complete transection of the cord may have oc- curred.
b Hyperextension may result in rupture of the anterior longitudinal ligament and disc with backward displacement of the vertebral body to narrow the spinal canal and impinge on the cord, before springing back.
c Compression, combined with flexion, may re- sult in a wedge-shaped fracture of the vertebral body. Severe compression injuries may result in a comminuted fracture with fragments en- croaching on the spinal canal.
3 Thoracic. The thoracic spine is relatively stable owing to the splinting afforded by the rib cage and sternum. Pathological fractures, commonly a result of osteoporosis or secondary tumour, are more common in this region.
4 Thoracolumbar. The thoracolumbar junction is relatively unsupported, and susceptible to inju- ries caused by flexion, rotation and compression.
Such injuries may follow a fall from a height land- ing on the feet or the buttocks, or forward flexion of the spine in a decelerating car crash, or a heavy weight falling on the shoulders.
5 Lumbar.
a Compression injuries may cause wedge- shaped fractures where the body of the verte- bra collapses.
b Burst fractures with comminution of the ver- tebral body and hence disruption of anterior and middle columns may occur following axial compression and result in an unstable frac- ture, often with cord or cauda equina damage Interspinous
ligament Annulus
fibrosus
Anterior longitudinal ligament
Posterior longitudinal ligament
Supraspinous ligament
1 2 3
Figure 16.2 The three-column spine concept.
The spine
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if bone fragments encroach into the canal.
Such fractures are often associated with crush- ing of the intervertebral disc.
In practice, the most common fractures are those in the cervical and thoracolumbar regions.
Clinical features
There is the typical history of injury followed by lo- calized pain, bruising, tenderness and often a ky- phus. Careful neurological examination is imperative (Box 16.1).
Box 16.1 Examining neurological injury
The examination of nerve injuries requires testing for sensation, power and reflexes. The components of sensation include light touch, vibration and joint position sense (dorsal columns), and temperature and pain (spinothalamic tract). Abnormalities should be noted in relation to both dermatome and, in the case of peripheral nerve injuries, innervation.
Motor responses should be examined in relation to spinal level or peripheral nerve according to injury.
Movement Muscle responsible Innervation
Arm abduction Deltoid C5, 6
Elbow flexion Biceps C5, 6
Wrist extension Forearm extensors C6, 7
Elbow extension Triceps C7, 8
Finger abduction Intrinsic muscles of hand C8, T1
Hip flexion Iliopsoas L2, 3
Knee extension Quadriceps femoris L2, 3, 4
Foot dorsiflexion Tibialis anterior, extensor hallucis longus, extensor digitorum longus L4, 5
Knee flexion Hamstrings L5, S1
Hallux extension Extensor hallucis longus L5, S1
Foot plantarflexion Gastrocnemius, soleus, tibialis posterior, flexor hallucis longus, flexor
digitorum longus S1, 2
Anal tone Anal sphincter S2, 3, 4
Motor responses should be graded according to the Medical Research Council (MRC) scale:
0 Total paralysis 1 Flicker of movement
2 Active movement with gravity eliminated
3 Normal movement against gravity but not against additional resistance 4 Movement against both gravity and resistance, but less than normal 5 Normal power
The reflexes are innervated as follows:
Biceps C5, 6
Triceps C7, 8
Knee L3, 4
Ankle S1, 2
• Plantar reflex. Extension is abnormal and indicates an upper motor neurone lesion.
Two other reflexes are useful in the assessment of patients with spinal cord injuries, the presence of which suggests an incomplete cord lesion.
• Bulbocavernosus reflex. Contraction of the anal sphincter in response to pinching of the penile shaft.
• Anal reflex. Contraction of the anus in response to stroking of the perianal skin.
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The spineIt is obligatory to examine every person with a head injury for suspected spinal fracture, as this is eas- ily overlooked in the unconscious patient. Unskilled handling of such a case may produce an irreparable spinal injury.
Special investigations
• Spine X-ray. The exact type of fracture is usually shown. Lateral films are the most important. Cer- vical spine films should show all seven cervical vertebra and T1. Additional views, such as a swim- mer’s view (a front-crawl position) or an oblique view to visualize the lower cervical spine, and an open-mouth view to show the dens, may be nec- essary.
• Computed tomography (CT) to confirm a fracture and demonstrate the extent of comminution.
• Magnetic resonance (MR) imaging to assess injury to the spinal cord or intervertebral disc.