SPECIAL POINTS IN THE INVESTIGATION OF BACK AND SCIATIC SYMPTOMS

History

Special attention should be paid to the mode of onset of the symptoms, whether they are periodic or constant, whether they are getting worse or better, and what relieves them or aggravates them. The precise location of the back pain and its character should be determined. The patient should be asked to what he or she attributes the symptoms: a history of a jarring strain, a fall, or an unaccustomed lifting job may be pertinent. Exacerbation of the pain on coughing or sneezing, which raises intracranial pressure, is indicative of an organic lesion.

Significance of sciatica. If pain radiates into the lower limb its character and exact distribution must be ascertained. Two distinct types of sciatica can be recognised. If the pain is severe and radiates in a well-defined course that can be outlined on the skin surface, and especially if it is accompanied by motor, sensory, or reflex impairment, it suggests mechanical interference with nerve fibres of the lumbar or sacral plexus, as for instance by a prolapsed disc or a tumour. On the other hand, if it takes the form of a vague diffuse ache, ill defined in its distribution, it is more likely to be a ‘referred’ pain originating in a disordered joint or ligament.

Exposure

The patient should be stripped completely, except for undergarments and, in women, a brassière.

Steps in routine examination

A suggested plan for the routine clinical examination of the back is summarised in Table 13.1.

Table 13.1 Routine clinical examination in suspected disorders of the back

1. LOCAL EXAMINATION OF THE BACK, WITH NEUROLOGICAL SURVEY OF THE LOWER LIMBS
(Patient standing)	Costo-vertebral joints
Inspection	Range indicated by chest expansion
Bone contours and alignment:	Sacro-iliac joints
(?visible deformity)	(Impracticable to assess range)
Soft-tissue contours	? Pain on movement imparted by
Colour and texture of skin	lateral compression of pelvis
Scars or sinuses	(Patient recumbent)
Palpation	Palpation of iliac fossae
Skin temperature	Examine specifically for abscess
Bone contours	or mass
Soft-tissue contours	Neurological state of lower limbs
Local tenderness	Straight leg raising test
Movements	Muscular system
Spinal joints	Sensory system
Flexion	Reflexes
Extension
Lateral flexion
Rotation
? Pain on movement
? Muscle spasm
2. EXAMINATION OF POTENTIAL EXTRINSIC SOURCES OF BACK PAIN AND SCIATICA
This is important if a satisfactory explanation for the symptoms is not found on local examination. The investigation should include:
1. the abdomen
2. the pelvis, including rectal examination
3. the lower limbs
4. the peripheral vascular system
3. GENERAL EXAMINATION
General survey of other parts of the body. The local symptoms may be only one manifestation of a widespread disease

Assessment of deformity

Any visible or palpable alteration of shape or posture of the spinal column should be noted. Deformity may occur in the sagittal plane, in the form of kyphosis (excessive forward curve or stoop) or lordosis (hollow back); or it may occur in the coronal plane as a lateral curvature (scoliosis). Combined curves and rotational deformity may also occur.

Movements of the spinal column and related joints

The spinal column. The joints of the spinal column must necessarily be considered as a group, for it is impracticable to study the movement of each joint independently. The movements to be examined are flexion, extension, lateral flexion to right and left, and rotation to right and left. It should be noted particularly whether the spinal muscles go into protective spasm when movement is attempted. Flexion: Instruct the patient to stretch the fingers towards the toes, keeping the knees straight. It is important to judge what proportion of the movement occurs at the spine and how much is contributed by hip flexion (Fig. 13.1). Some patients can almost reach their toes, despite a stiff back, simply by flexing unusually far at the hips. (Normally the hamstrings limit hip flexion to about 90 ° when the knees are straight.) The range may be expressed roughly as a percentage of the normal, or as the distance by which the fingers fail to reach the floor. A more accurate assessment is made by measuring the linear widening of the interspinous spaces as indicated by a tape measure laid along the line of the spinous processes, which may be marked with a pen. The excursion of the spinous processes between full extension and fullest flexion may thus be measured on the tape. An excursion of four centimetres between the twelfth thoracic spinous process and the first sacral prominence between full extension and fullest flexion indicates good lumbar mobility. Extension: Instruct the patient to arch the spine backwards, looking up at the ceiling. Judge the range and express approximately as a percentage of the normal; or measure the excursion as described above. Lateral flexion: Instruct the patient to slide each hand in turn down the lateral side of the corresponding thigh. Observe the range. Rotation: With the feet fixed, the patient rotates the shoulders towards each side in turn. Hold the pelvis steady, and note the range of spinal rotation as distinct from that which occurs at the knees and hips.

Fig. 13.1 A Normal flexion of lumbar spine. A tape measure laid along the line of the spinous processes will show widening of the interspinous spaces as the column flexes. B Apparent or false flexion due entirely to movement at the hips, the hamstrings being unusually lax. A tape measure laid along the line of the spinous processes shows little excursion of their tips. In assessing trunk flexion it is important to judge in this way how much of the movement occurs at the spinal joints and how much at the hips.

Related joints. The costo-vertebral joints: The mobility of the costo-vertebral joints is judged from the range of chest expansion. The normal difference in chest girth between full inspiration and full expiration is about 7 or 8 cm. A marked reduction of chest expansion is of particular significance when ankylosing spondylitis is suspected. The sacro-iliac joints: It is not practicable to measure the range of sacro-iliac movement. But the joints should be moved passively to determine whether pain is produced, as it will be in arthritic conditions of the joints. A simple method is to grip each iliac crest and compress the pelvis strongly from side to side.

Palpation of iliac fossae and groins

Palpation of the iliac fossae and groins is an essential step in the examination of the back. Its specific purpose is to determine whether or not there is a soft-tissue thickening or abscess. It should be remembered that a ‘psoas’ abscess originating from a tuberculous lesion of the lumbar spine first becomes palpable deep in the iliac fossa. Such an abscess is felt most easily by pressing the flat palmar surface of the hand and fingers against the flat inner aspect of the iliac bone. To do this the surgeon must stand at the side of the couch corresponding to the side being examined – that is, he must stand on the right of the patient to examine the right iliac fossa and on the left to examine the left iliac fossa (Fig. 13.2).

Fig. 13.2 Palpating the iliac fossae for abscess. This is an essential step in the routine examination of the spine.

Neurological examination of the lower limbs

Disorders of the back are so frequently accompanied by radiating pain, paraesthesiae, or other manifestations in the lower limb that a neurological survey should be carried out as a routine.

Straight leg raising test. Holding the knee straight, lift each lower limb in turn to determine the range of pain-free movement (normal = 90 °; often more in women) (Fig. 13.3). When associated with clearly defined sciatica (and in the absence of gross disease of the hip), marked impairment of straight leg raising by pain suggests mechanical interference with one or more of the roots of the sciatic nerve. The pain is easily explained. Even a normal sciatic nerve is tautened by straight leg raising, though not to the point of causing pain by dragging on the meningeal sheath that encloses the nerve root. If a nerve is already stretched or anchored, as by a protruded piece of an intervertebral disc or a tumour, the further tautening entailed in lifting the limb is sufficient to cause pain.

Fig. 13.3 The straight leg raising test, an important part of the neurological examination of the lower limbs.

When a nerve is tensely stretched, raising the straight leg on the unaffected side may cause pain on the affected side. This sign, termed the crossed sciatic reflex, is a well-recognised feature of prolapsed lumbar intervertebral disc with nerve pressure.

Muscular system. Examine the muscles for wasting, hypertrophy, and fasciculation. Note the tone and test the power of each muscle group, comparing it with its counterpart in the opposite limb. Circumferential measurement is a reliable method of comparing the bulk of the calf muscles, the girth being measured at the widest part or ‘equator’ (Fig. 13.4A). Circumferential measurement of the thighs, on the other hand, tends to be inaccurate, and may be misleading, on account of the conical shape of the thigh (Fig. 13.4B). Often a more accurate assessment of the relative volume of the two thighs is obtained from inspection and palpation. If the thighs are measured, the girth should be taken on each side at an equal distance above the knee – 12 or 15 cm above the upper margin of the patella is usually a convenient level.

Fig. 13.4 A Girth measurement at the widest part is a reliable method of comparing the bulk of the calf muscles on the two sides. B Measurement is less reliable in comparing the bulk of the thigh muscles because of the conical shape of the thigh and the difficulty of taking the measurement at an exactly comparable level on each side.

Power of the muscles is estimated in comparison with the opposite side. Not only the major muscle groups should be tested: significant information may emerge from assessing the power of the toe muscles, and in particular of the extensor hallucis longus, which characteristically is weakened by lesions (such as prolapsed intervertebral disc) involving the fifth lumbar nerve.

Sensory system. Examine the patient’s sensibility to touch and pin prick, paying particular attention to the sites of any impairment. A knowledge of the innervation of the dermatomes (Fig. 13.5) is essential as this may give an indication of the level of any nerve roots affected. When indicated, test also the sensibility to deep stimuli, joint position, vibration, and heat and cold.

Fig. 13.5 Sensory dermatomes of the lower limb. A knowledge of the root innervation may provide information on the possible level of associated disease in the lumbo-sacral spine.

Reflexes. Compare on the two sides the knee jerk (dependent mainly on the L4 nerve) and the ankle jerk (mainly S1). It is important to note not only the presence or absence of the response, but also any difference of intensity (Fig. 13.6). Test the plantar reflex.

Fig. 13.6 A The patellar reflex is dependent mainly on L4 nerve. B In testing the calcaneal reflex (mainly S1 nerve), slight inequalities between the two sides can best be detected if the patient lies prone, with the knee flexed 45 ° and the ankle at 90 °.

Electromyography. Electromyographic examination of selected muscles in the lower leg may have an occasional place in helping to establish whether or not there is degeneration in the innervating lumbar or sacral nerve, as indicated by abnormal potentials in the resting muscle. For instance, abnormal potentials in the lateral half of the gastrocnemius muscle or in the extensor digitorum brevis suggest degeneration of the fifth lumbar nerve, whereas abnormal potentials in the medial half of the gastrocnemius or in the soleus indicate the first sacral nerve.

Imaging

Radiographic examination. If the complaint is clearly localised to the thoracic spine, antero-posterior and lateral radiographs of that area alone will usually suffice. If the lumbar spine is the part complained of, radiographs should include not only antero-posterior and lateral views of the lumbar spine but also at least one view of the sacro-iliac joints, pelvis, and hip joints. In cases of doubt additional projections may be required. Oblique projections – from half right and half left – are essential for the proper study of the sacro-iliac joints and the posterior intervertebral (facet) joints of the lumbar region. If a spinal tumour is suspected further imaging with magnetic resonance scanning is required.

Other methods of imaging. Radioisotope bone scanning p. 21 is of particular value in examination of the spinal column, especially in the early detection of metastatic deposits.

Computerised tomography (CT scanning) p. 12 is valuable in selected cases. It gives cross-sectional images of the trunk that reveal bony abnormalities very clearly.

Magnetic resonance imaging (MRI) is even more informative in demonstrating the intervertebral disc substance, the nerve roots, other soft tissues, and their relationship to the bony structures.

Discography (radiography after injection of radio-opaque fluid into the nucleus pulposus) indicates the integrity or otherwise of the disc, but the technique has been largely superseded by magnetic resonance imaging.

Extrinsic sources of back pain and sciatica

The back offers many pitfalls in diagnosis. Sometimes there are no local symptoms to indicate that the spine is the seat of the disorder, pain being referred entirely to the buttock or to the lower limb. Thus patients often complain only of pain ‘in the hip’ or ‘in the leg’ when the true source of the trouble is the lumbar spine. Conversely, the symptoms may suggest a spinal lesion when in fact they arise from an affection of the abdomen, pelvis, or lower limb, or from occlusion of a major artery or a leaking aortic aneurysm. Finally, it should always be remembered that back symptoms may be no more than a local manifestation of a generalised skeletal disease.

Thus the investigation of back or sciatic symptoms must extend further than a study of the spine itself; it must include an examination of the abdomen, pelvis, lower limbs, and vascular system, and a general survey of the rest of the body.

CONGENITAL ABNORMALITIES AND DEFORMITIES

LUMBAR AND SACRAL VARIATIONS

Minor variations of the bony anatomy are common, especially in the lumbar and sacral regions. Most are of little practical importance. They include: deficient or rudimentary lowest ribs; incomplete or complete incorporation of the fifth lumbar vertebral body in the sacrum (sacralisation of the fifth lumbar vertebra); persistence of the first sacral segment as a separate vertebra (lumbarisation of the first sacral vertebra); and over-development of the fifth lumbar transverse process on one or both sides with, in marked cases, a false joint between the hypertrophied process and the ilium (Fig. 13.7A). In the last- mentioned condition the false joint is sometimes a source of pain.

Fig. 13.7 Three congenital anomalities of the spine. A Hypertrophied transverse process forming false joint with ilium. B Hemivertebra, an occasional cause of scoliosis. C Four examples of spina bifida. In all, the neural arch of the vertebra is deficient posteriorly. In the first diagram, representing spina bifida occulta, there is no other deficiency; the skin and soft tissues are intact. In the second diagram overlying soft tissues are also deficient and the spinal theca bulges backwards to form a meningocele. In the third diagram nerve elements are also displaced backwards within the bulging sac (myelomeningocele). In the final diagram skin is deficient as well, and nerve elements are exposed on the surface (rachischisis).

SCOLIOSIS

The term scoliosis denotes lateral curvature of the spine. The deformity may be ‘structural’, implying a permanent change in the bones or soft tissues, or it may be no more than a temporary disturbance produced by reflex or postural activity of the spinal muscles. Five types can be recognised:

1 infantile scoliosis, a type seen in very young children which may either resolve to normal or become progressively worse

2 primary or ‘idiopathic’ structural scoliosis, a well-defined group of unknown cause arising in children

3 secondary structural scoliosis, a miscellaneous group in which the curvature is secondary to a demonstrable underlying disorder

4 compensatory scoliosis

5 sciatic scoliosis, a temporary deformity.

Infantile scoliosis

Infantile scoliosis begins in the first year of life as a simple curve, usually convex to the left, without known cause. There are two subgroups – resolving and progressive – and it is usually possible to distinguish them by the radiographic appearance.

Idiopathic structural scoliosis

Idiopathic scoliosis is the commonest and the most important type of structural scoliosis. It begins in childhood or adolescence and tends to increase progressively until the cessation of skeletal growth. It sometimes leads to severe and ugly deformity, especially when the thoracic region is the part affected. The exact cause of the growth disturbance is unknown: the children are otherwise healthy. The condition is much commoner in girls than in boys. This fact, together with its frequent onset at puberty, suggests a possible link with the hormonal control of bone growth. Recent evidence has suggested a genetic link with the disorder and several candidate genes are currently under investigation.

Pathology. Any part of the thoraco-lumbar spine may be affected. There is a primary structural curve, with secondary compensatory curves above and below. The pattern of curve and its natural evolution are fairly constant for each site, and the following types are recognised: lumbar scoliosis, thoraco-lumbar scoliosis, and thoracic scoliosis (Fig. 13.8A). The lateral curvature is constantly accompanied by rotation of the vertebrae on a vertical axis, the body of the vertebra rotating towards the convexity of the curve and the spinous process away from the convexity. By thrusting the ribs backwards on the convex side this rotation increases the ugliness of the deformity (Fig. 13.8).

Fig. 13.8 A Idiopathic scoliosis in an adolescent girl. The main curve is in the thoracic region. There is marked rotation of the vertebrae, causing posterior prominence of the ribs on the side of the convexity. In lumbar scoliosis the deformity is much less noticeable. B In forward flexion the ugliness of the deformity caused by the backward rotation of the ribs on the convex side of the curve becomes more apparent.

Clinical features. The onset is usually in middle childhood – often between the ages of 10 and 12 years, at the time of the adolescent growth spurt.

In children deformity is usually the only symptom. Pain is occasionally a feature in adults with long-standing deformity, particularly with structural curves in the lumbar region of the spine.

Course and prognosis. The outlook depends upon the age at onset and upon the site of the primary curve. The ultimate visible deformity tends to be worst in thoracic scoliosis and least in lumbar scoliosis. The curvature tends to increase until the end of the period of spinal growth, but not significantly thereafter. In general, therefore, the earlier the onset the worse the prognosis.

Treatment. The first essential is to assess the prognosis for progression of the deformity from a consideration of the age of onset and the site and severity of the curve. This requires the identification of the first and last vertebrae in the primary curve and the measurement of the Cobb angle between them on an erect AP radiograph of the spine (Fig. 13.9). When the prognosis is good (for instance, in most cases of lumbar scoliosis) expectant treatment, with regular clinical and radiological reviews every six months, may be all that is required. But when the prognosis is poor (as in thoracic scoliosis with early onset or a curve in excess of 45–50^°) active treatment is advised. This usually necessitates operation, and much surgical endeavour has been spent in the quest for an effective and safe method of correcting the deformity and maintaining the correction while fusion occurs. Surgical treatment is usually deferred until early adolescence to minimise the loss of height which may result from fusion of a significant length of the growing spine. To prevent further deterioration in the curvature during this waiting period, conservative management with various types of orthotic bracing has been used.

Fig. 13.9 A and B Radiographs of thoraco-lumbar spine in an adolescent girl with an idiopathic scoliois. The measurement of the Cobb angle on the AP film shows a severe curve of 55 ° that would justify surgical treatment.

For many years the brace most commonly employed was the Milwaukee brace. This used the principle of three-point correction by distracting the spine between a pelvic band and an occipito-cervical support, with additional lateral pressure from a pad applied to the chest wall at the apex of the curvature. Recently doubt has been cast on the effectiveness of this type of bracing, and because of frequent problems of acceptance by the patient, an alternative under-arm thoraco-lumbar jacket, or Boston brace (Fig. 13.10), has been used. This provides only two-point correction and it acts by flattening the lumbar lordosis; thus it is most suitable for lower curvatures with an apex below the ninth thoracic vertebra.

Fig. 13.10 Front and back view of a thoraco-lumbar moulded orthosis used for the conservative treatment of scoliois. The brace does not correct the deformity, but may prevent further deterioration of minor curves until skeletal maturity is reached.

The principle of surgical treatment is to fuse the joints of all the vertebrae within the primary curve, after having first achieved the greatest possible correction of the curvature. When surgical treatment was first introduced correction was obtained by pre-operative traction or corrective plaster casts. It is now routinely gained at the time of operation by the use of an internal corrective implant. For many years the device used for this purpose was the Harrington distraction rod. This was inserted posteriorly in the concavity of the curve between two hooks placed under the laminae of the top and bottom vertebrae and then forcibly elongated to produce straightening. The results from this technique were encouraging, with up to 50% correction of the lateral curvature, though this was not reflected in improvement of the cosmetic deformity, which largely results from vertebral rotation. This led to a search for other methods of correction including the use of anterior interbody fixation devices, though these necessitated thoracotomy with its associated morbidity in terms of decreased lung function. Currently most specialist surgeons favour posterior correction with multiple-level segmental pedicle screw fixation devices (Cotrel-Dubousset instrumentation) (Fig. 13.11). This was an advance over the Harrington instrumentation because it improved correction in both the sagittal and coronal planes.

Fig. 13.11 A and B Radiographs of the same patient shown in Figure 13.9 after surgical correction and fusion with segmental pedicle fixation which has reduced the curve to 8 °.

Other methods of fixation and correction may be required for more severe curvatures, or when abnormal vertebral pathology exists, as in congenital curvatures which may include a kyphotic component.

The place of these various specialised techniques has not yet been finally established: they all carry a risk of neurological complications and require intraoperative spinal cord monitoring, which is only available in specialist centres.

It must be emphasised that it is impossible to prevent the increase of a progressive scoliotic deformity by exercises alone, though these are an important adjunct to bracing, and useful in preserving mobility. The aim of all treatment must be to minimise progression, or to correct the deformity to an acceptable level at skeletal maturity. It is difficult and often impracticable to correct long-standing deformity in adults by any method.

Secondary structural scoliosis

In this group the spinal curvature is secondary to a demonstrable underlying abnormality.

Causes. The three commonest underlying causes are congenital abnormalities (especially hemivertebra), poliomyelitis with residual weakness of the spinal muscles (paralytic scoliosis), and neurofibromatosis.

Pathology. In congenital hemivertebra there is a sharp angulation at the site of the anomaly, with compensatory curves above and below (Fig. 13.7B). Scoliosis following poliomyelitis is explained by unequal pull of the muscles on the two sides. The mechanism of scoliosis complicating neurofibromatosis is not clear; in this type the deformity may be very severe.

Clinical features. In most cases the visible deformity is the only symptom. The age of onset, site, nature, and severity of the curve vary with the underlying cause.

Complications. In exceptional cases of severe long-standing scoliosis the sharp angulation of the spinal cord over the apex of the deformity may cause interference with cord function, with consequent neurological manifestations leading in the worst cases to total paralysis below the level of the obstruction.

Treatment. In most cases treatment is along the lines suggested for idiopathic scoliosis.

Compensatory scoliosis

Lumbar scoliosis is seen as a compensatory device when the pelvis is tilted laterally – as, for instance, when the lower limbs are unequal in length, or when there is a fixed abduction or adduction deformity at one or other hip. In such a case it is only by curving the lumbar spine through an angle equal to the pelvic tilt that the trunk can be held vertical. Usually there is no intrinsic abnormality of the spine itself, and the scoliosis disappears automatically when the pelvic tilt is corrected. In cases of many years’ duration, however, the lumbar scoliosis may become fixed by adaptive shortening of the tissues on the concave side.

Sciatic scoliosis

Sciatic scoliosis is a temporary deformity produced by the protective action of muscles in certain painful conditions of the spine.

Cause. In many cases the underlying cause is a prolapsed intervertebral disc impinging upon a lumbar or sacral nerve. But the deformity may also be observed in some cases of acute low back pain p. 241, the pathogenesis of which is not entirely clear.

Pathology. The curve is in the lumbar region. The abnormal posture is assumed involuntarily in an attempt to reduce as far as possible the painful pressure upon the affected nerve or joint, usually from a lumbar disc protrusion.

Clinical features. The predominant feature is severe back pain or sciatica, aggravated by movements of the spine (see prolapsed lumbar intervertebral disc, p. 236. The onset is usually sudden. The scoliosis is poorly compensated; so the trunk may be tilted over markedly to one side (see Fig. 13.27, p. 238. The curvature is not associated with rotation of the vertebrae.

Fig. 13.26 Stages in prolapse of an intervertebral disc. A The annulus fibrosus is torn but there has been no extrusion of the nucleus pulposus. B Extrusion of nuclear material through the rent. The posterior longitudinal ligament is stretched but the protrusion has not reached the nerve. C The protrusion is larger and the nerve is stretched over it. Sometimes a fragment of the torn annulus itself protrudes backwards.

Treatment. The treatment is that of the underlying condition.

TUBERCULOSIS OF THE THORACIC OR LUMBAR SPINE (TUBERCULOUS SPONDYLITIS; POTT’S DISEASE¹)

Tuberculosis of thoracic or lumbar vertebral bodies was formerly one of the commonest forms of skeletal tuberculosis, and it is still prevalent in some Eastern countries, though now seen only rarely in the West.

Pathology. The infection begins at the anterior margin of a vertebral body, near the intervertebral disc (Fig. 13.12A). The disc itself is usually involved at an early stage. The extent of the destruction varies widely from case to case. Commonly there is complete destruction of one intervertebral disc with partial destruction of the two adjacent vertebrae, most marked anteriorly (Fig. 13.12B). But the changes may extend over several spinal segments; or, on the other hand, they may be confined to a single intervertebral disc, without evident bone involvement (Fig. 13.13A). Anterior collapse of the affected vertebrae leads to an angular kyphosis (Figs 13.12B, 13.13B and 13.14).

Fig. 13.12 Tuberculosis of the spine. The infection begins anteriorly near an intervertebral disc, which is soon destroyed A. It may spread to adjacent vertebrae, which collapse in front, with consequent angular kyphosis B.

Fig. 13.13 A Early tuberculous lesion causing a narrowed lumbar disc space in a young adult. Narrowing of a disc space without osteophytic spurring of the vertebral margins always suggests infection. B Severe tuberculous erosion of two lumbar vertebrae, with anterior collapse. The vertebra below also shows erosion at its upper anterior corner. One intervertebral disc is destroyed and the one above is much narrowed.

Fig. 13.14 Tuberculosis of the thoracic spine in a child. Note in the antero-posterior view the typical fusiform appearance of a paraspinal abscess, an almost constant feature of thoracic spinal tuberculosis. In the lateral view two vertebral bodies are seen partly collapsed in a wedge-shaped mass; the disc between them has been destroyed.

Abscess formation is usual. In the thoracic region pus collects around the spinal column, forming a fusiform paraspinal abscess (Fig. 13.14); or it may track towards the surface between ribs. From the lower thoracic or lumbar region pus tracks downwards behind the fascial sheath of the psoas muscle and generally bursts into the compartment behind the iliacus fascia to form a palpable abscess in the iliac fossa (psoas abscess). An abscess occasionally points posteriorly, or in the thigh. As in most instances of skeletal tuberculosis, the inflammation is low-grade and chronic rather than acute: hence the term ‘cold abscess’ for the quiet suppuration that is a common feature.

Secondary effects. An abscess or mass of granulation tissue encroaching upon the spinal canal may interfere with the spinal cord or with a spinal nerve. In cases of long-standing severe kyphosis the spinal cord is occasionally damaged by the bony ridge at the site of deformity.

Clinical features. The disease is commonest in young adults. One or more of the following symptoms may be present:

On examination, the patient often looks ill. There may be visible or palpable angular kyphosis. There is local tenderness on firm palpation or percussion over the affected vertebrae. All spinal movements are greatly restricted and when they are attempted the spinal muscles go into protective spasm. An abscess may be detected over the thoracic wall or in the flank, iliac fossa, or upper thigh. Signs of spinal cord compression (‘Pott’s paraplegia’) or of a nerve root lesion may be present. Tuberculous lesions are often manifest elsewhere.

Imaging. On radiographic examination the earliest signs are narrowing of an intervertebral space (Fig. 13.13A) and local vertebral osteoporosis. Later, there is usually destruction of bone at the anterior margin of one or more of the vertebral bodies, leading to anterior collapse and wedge-shaped deformity of the affected vertebrae (Figs 13.13B and 13.14). An abscess shadow is nearly always visible: in the thoracic region it is seen as a fusiform paraspinal shadow (Fig. 13.14); in the lumbar region it is indicated by lateral bulging of the psoas outline, usually on one side. In the healing stage the bone outline in the area of destruction becomes sharper, and normal density is regained. Abscesses may become calcified. Magnetic resonance imaging (MRI) is useful in defining the extent of the soft-tissue abscess more clearly, especially if there are signs of spinal cord dysfunction (Fig. 13.15). Ultrasound scanning is useful in defining the extent of an abscess.

Fig. 13.15 A Tuberculous infection of the lumbar spine shown on sagittal MR scan. The L2 disc is destroyed as are the adjacent end vertebral endplates and a soft-tissue mass is seen anterior to the spine with some abnormal soft tissue also extending into the spinal canal. B An axial T2 scan demonstrates large fluid-filled para-spinal masses, which are the ‘cold’ psoas abscesses typical of tuberculous infections.

Investigations. The erythrocyte sedimentation rate is raised in the active stage. The Mantoux test is positive. Tubercle bacilli can sometimes be isolated from aspirated pus.

Complications. These include:

Paraplegia may arise early – that is, during the active stage of the disease – when it is caused by the pressure of pus or granulation tissue; or it may arise many years after healing has occurred, from mechanical impedance of the spinal cord where it is sharply angled at the apex of a severe kyphos (‘late onset paraplegia’).

Prognosis. The prognosis is worse in certain Asian and African countries where the disease tends to be more florid, than in Britain, North America and the Antipodes where it is usually mild and responsive to treatment.

Treatment. Treatment of spinal tuberculosis is now much more often ambulatory than it was in the past, largely because of the efficacy of antituberculous drugs. Nowadays treatment may entail only a brief stay in hospital – or indeed it may often be carried out entirely on an out-patient basis.

Conservative treatment. Conservative management relies almost entirely upon antibacterial agents. Results from long-term controlled trials have now shown that short-course regimens based on isoniazid, rifampicin and pyrazinamide for six to nine months are as effective as longer-term treatment for up to 18 months with the addition of streptomycin. In more severe disease local treatment for the spine may be required by a short period of bed rest or immobilisation by a plaster jacket for relief of pain, but in most cases antibiotic treatment can be continued on an ambulant outpatient basis. Adjuvant operation may be required in certain circumstances, mainly for the drainage of an abscess.

With this regimen, satisfactory healing may be expected in a high proportion of patients, though often with some residual kyphosis.

Operative treatment. The alternative management is by radical operation as developed by Hodgson in Hong Kong. This may promote more rapid healing. The affected part of the spinal column is approached anteriorly and all diseased bone is excised. Thereafter the gap is bridged by bone grafts. Adjuvant antibacterial agents are given. By this method the duration of treatment is shortened and kyphosis may often be prevented or corrected.

Relief of paraplegia. If paraplegia from compression of the spinal cord does not show rapid improvement after the commencement of antibacterial therapy the spinal canal should be decompressed by operation. Occasionally this may be achieved by costo-transversectomy alone (see above), particularly if a paraspinal abscess is the chief factor responsible for the compression. More reliably, it may be done by clearance of pus, necrotic tissue and diseased bone from the region of the spinal theca, either through an anterior approach or through a lateral route by unilateral excision of the pedicles of three or four vertebrae (lateral rhachotomy; antero-lateral decompression).

Assessment of cure. Signs of quiescence are: good general health; diminishing blood sedimentation rate; and arrest of the destructive process with hardening of the bony outlines as seen radiographically.

PYOGENIC INFECTION OF THE THORACIC OR LUMBAR SPINE (Pyogenic spondylitis; osteomyelitis of the spined; discitis)

Pyogenic infection of the spine is uncommon. It has often been confused with tuberculous spondylitis, which it may resemble clinically and radiographically, though it tends to run a more acute course.

Cause. It is caused by infection with the staphylococcus, streptococcus, pneumococcus, or occasionally with other bacteria such as the typhoid bacillus or other salmonella organisms, or Brucella abortus.

Pathology. Organisms usually reach the spinal column through the general blood stream, from a septic focus elsewhere. Other possible routes are through the spinal venous plexus from a focus in the pelvis, or through lymphatic channels from a neighbouring focus. As in tuberculous spondylitis, there is destruction of an intervertebral disc and erosion of the adjacent bone, with or without abscess formation. The spinal cord may be damaged by pressure, or by thrombosis of its vessels.

Clinical features. The clinical picture is inconstant: there are remarkable variations in the severity of the symptoms from case to case. The onset is often acute or subacute, and may be accompanied by pyrexia, with local pain and restriction of all movements by muscle spasm. A suppurative process elsewhere in the body is usually present or has recently subsided; or infection may follow operation for removal of displaced disc material, with consequent ‘discitis’.

Imaging. Radiographs show local rarefaction or erosion of bone, diminution of disc space, and sometimes sub-ligamentous new bone formation. MRI scanning may also reveal the extent of soft tissue and bone involvement by the infective abscess (Fig. 13.16). After healing, spontaneous bony fusion of affected vertebrae is often observed.

Fig. 13.16 A Sagittal MR scan of thoraco-lumbar spine with disc infection. In the lower thoracic region there is a narrowed disc space (arrow) which shows high signal on T2 indicating the presence of fluid. The discs above and below this level appear normal. B Sagittal T1 image of the same patient showing that the vertebrae on either side of the disc are of much lower signal. This indicates the presence of marked bone oedema and combined with the fluid in the narrowed disc allows a diagnosis of infective discitis to be made.

Investigations. The erythrocyte sedimentation rate is raised. Polymorpho-nuclear leucocytosis is to be expected. Serological studies can occasionally incriminate a particular organism, such as one of the salmonella group.

Treatment. Appropriate antibacterial drugs are given. The spine is rested, at first in bed, but later with a suitable brace, until healing occurs. An abscess may require early drainage, especially if the spinal cord is threatened.

RHEUMATOID ARTHRITIS OF THE SPINAL JOINTS (General description of rheumatoid arthritis, p. 134)

It has been noted above that rheumatoid arthritis often affects the cervical spine. Joints of the thoracic and lumbar spine may likewise be affected, but clinical manifestations are relatively uncommon. They consist in aching pain of a rather diffuse type, with impairment of spinal movements. The symptoms develop insidiously, without preceding injury. Examination of the limbs will usually reveal typical rheumatoid changes in several joints.

OSTEOARTHRITIS OF THE THORACIC AND LUMBAR SPINE (Spondylarthritis; spondylarthrosis; spondylosis)

Osteoarthritis of the thoracic or lumbar intervertebral joints is found very commonly in those used to heavy work, but it is not necessarily accompanied by symptoms.

Cause. Predisposing factors are:

As in other joints the cause of degeneration is unknown, but may be the manifestation of an ageing process in the cartilage tissue.

Pathology. The changes affect the central intervertebral (body-to-body) joints and the posterior intervertebral (facet) joints. One segment or several segments may be affected. In the central joints, which are affected first, there is degeneration with consequent narrowing of the intervertebral disc, and hypertrophy of bone at the joint margins leads to the formation of osteophytes (Fig. 13.17). In the posterior intervertebral (facet) joints the changes are those of osteoarthritis in any diarthrodial joint – namely, attrition of the articular cartilage and osteophyte formation (spurring) at the joint margins. These changes in the facet joints are probably the more important from a clinical point of view.

Fig. 13.17 Osteoarthritis of the lumbar spine. Marked narrowing of an intervertebral disc, with anterior osteophytes. Note also the slight posterior displacement of the upper vertebra. (See also Fig. 13.23B.)

Secondary effects. Rarely, osteophytes encroach upon an intervertebral foramen sufficiently to interfere with the function of the issuing nerve. Thinning of the articular cartilage of the posterior intervertebral (facet) joints reduces the stability of the affected segment and predisposes to one type of spondylolisthesis p. 242. In severe cases the osteophytes around the facet joints may encroach on the spinal canal resulting in the syndrome of spinal stenosis p. 245.

Clinical features. Spinal osteoarthritis can exist in quite marked degree without causing symptoms. But there is often a complaint of aching pain in the affected area, worse on activity or after prolonged standing or sitting in one position, and especially after stooping or lifting. Pain is often worse first thing in the morning, and there may be a feeling of stiffness when rising from a sitting position. In the lumbar region there is a tendency to acute exacerbations of pain, usually arising suddenly and lasting a few weeks. These are possibly explained by strain or momentary subluxation of an unstable degenerate joint. Interference with a nerve in a narrowed intervertebral foramen leads to radiating pain in the distribution of the affected nerve (girdle pain or sciatica according to the level affected).

On examination in the quiet phase, the objective findings are slight. Spinal movements may be moderately restricted, especially flexion; but there is no muscle spasm. If there is interference with a lumbar nerve root straight leg raising on the affected side is likely to be restricted. Apart from this, objective neurological signs are exceptional. During an acute exacerbation of pain there may be marked impairment of spinal movements, with muscle spasm.

Radiographic features. The changes are most obvious in the central (body-to-body) intervertebral joints, which show narrowing of the intervertebral space and osteophyte formation (spurring) at the joint margins (Fig. 13.17). Later the posterior intervertebral (facet) joints also show changes: there is narrowing of the joint space with sharpening of the margins of the facets. These changes are seen clearly only in oblique projections or on CT scans.

Diagnosis. Osteoarthritis has to be distinguished from other causes of back pain and from other causes of radiating nerve pain (girdle pain or sciatica) (see Fig. 13.29, p. 240). It should be remembered that the demonstration of osteoarthritic changes in the radiographs does not necessarily mean that the arthritis is the cause of a patient’s symptoms, for spinal osteoarthritis is common and often painless. The diagnosis is always presumptive rather than proved, and it is justified only when other possible causes have been excluded by careful consideration of the history, clinical examination, and radiographs.

Fig. 13.29 Eleven causes of pain in the back or lower limb. All must be considered in differential diagnosis of prolapsed intervertebral disc.

Treatment. This depends upon the severity of the disability. In mild cases treatment is unnecessary: explanation and reassurance suffice.

Thoracic spine. In osteoarthritis of the thoracic spine the symptoms are seldom severe, and if treatment is required a course of active spinal exercises to strengthen the posterior muscles is usually sufficient.

Lumbar spine. In lumbar osteoarthritis with moderate disability a well-fitted surgical corset (orthotic brace) will usually afford adequate relief. Physiotherapy, mainly by exercises and passive mobilisation, may also be helpful. Heavy lifting and similar strains to the back should be strictly avoided. Rarely, if the pain from a localised lesion is bad enough to cause serious hardship, operative fusion of the affected segments of the spine may be required.

ANKYLOSING SPONDYLITIS

In ankylosing spondylitis there is chronic inflammation, progressing slowly to bony ankylosis, of the joints of the spinal column and occasionally of the proximal limb joints.

Cause. This is unknown, but may represent an auto-immune response to an infecting organism. The condition is distinct from rheumatoid arthritis, although it has sometimes been loosely termed ‘rheumatoid spine’. There is a strong hereditary link to the HLA-B27 gene, which is present in 80–90% of patients. There is also a relationship with certain types of sero-negative chronic juvenile arthritis in members of the family.

Pathology. The disease usually begins in the sacro-iliac joints, whence it usually extends upwards to involve the lumbar, thoracic, and often the cervical spine. In the worst cases the hips or shoulders are also affected. The articular cartilage, synovium, and ligaments show chronic inflammatory changes and eventually they become ossified. After several years the inflammatory process becomes quiescent.

Clinical features. The disease has a strong male preponderance (M:F = 3:1) and it nearly always begins between the ages of 16 and 25. The early symptoms are aching pain in the lower back and increasing stiffness. Later, the pain migrates upwards. Diffuse radiating pain down one or both lower limbs is also common. On examination the predominant finding is marked limitation of all movements in the affected area of the spine (‘poker back’). When the thoracic region is involved chest expansion is markedly reduced – often to less than 2.5 cm (normal = 7.5 cm) – from ankylosis of the costo-vertebral joints: this is an important diagnostic feature. In a few cases the hips or shoulders are affected, with pain and limitation of movement.

Imaging. Radiographs in the early stage show fuzziness and widening of both the sacro-iliac joints, so that the joint outline is no longer clearly defined (Fig. 13.18). MRI scanning is far more sensitive in detecting these early changes in the sacro-iliac joints (Fig. 13.19). Later, the sacro-iliac joints are completely obliterated and, if the disease progresses, the intervertebral joints in the lumbar, thoracic, and sometimes even the cervical region undergo bony ankylosis, with prominent anterior bridging of the vertebral bodies producing the so-called ‘bamboo spine’ (Fig. 13.20).

Fig. 13.18 AP radiograph of sacroiliac joints. The joints are completely fused showing the typical appearances of advanced sacroiliitis seen in ankylosing spondylitis.

Fig. 13.19 Coronal T2 weighted MR scan of sacroiliac joints in ankylosing spondylitis. There is oedema seen as high signal on either side of the left SI joint (arrow), which indicates an active sacroiliitis. The MR scan is much more sensitive than plain radiographs at detecting early changes in the disease.

Fig. 13.20 A and B Radiographs of a fused lumbar spine in advanced ankylosing spondylitis. There is ossification of the anterior longitudinal ligament and of the annulus of the discs at all levels giving the so-called ‘bamboo spine’ appearance typical of the disease.

Investigations. The erythrocyte sedimentation rate and C-reactive protein levels are raised while the disease is active. In 90% of cases the test for HLA-B27 antigen is positive.

Diagnosis. In the early stages ankylosing spondylitis has to be distinguished from other causes of back pain and sciatica (see Fig. 13.29, p. 240). The marked limitation of spinal movement, the reduced chest expansion, the typical radiographic features, and the raised erythrocyte sedimentation rate are diagnostic.

Course and complications. The disease usually ceases to progress after ten or fifteen years, leaving permanent stiffness, the extent of which varies widely from case to case. Complications include fixed flexion deformity of the spine (Fig. 13.21A), intercurrent respiratory infections, and iridocyclitis, which in severe cases may lead to blindness. There is also a relationship with Crohn’s disease (regional ileitis), which may co-exist.

Fig. 13.21 A Patient with long-standing ankylosing spondylitis complicated by rigid flexion deformity. B After corrective osteotomy in the lumbar region.

Treatment. Treatment is rather unsatisfactory, in that no method is known by which the disease process can be halted and spinal mobility preserved. In most cases the mainstay of treatment is a non-steroidal anti-inflammatory agent in the first instance. Steroid drugs are inappropriate except for ophthalmic complications. The advent of new biological drugs based on monoclonal antibodies has allowed anti-tumour necrosis factor alpha (antiTNF-α) to be used in the early stages of the disease with moderate success, but the long-term results are not yet available.

Apart from these measures, treatment should be directed towards preserving function and preventing spinal deformity. Activity rather than rest should be prescribed. Special exercises should be practised to make the most of such movement as remains. The patient should adopt the habit of sleeping flat on a firm mattress, ideally in the supine position with a single pillow, to maintain normal spinal alignment.

If a severe flexion deformity of the spine occurs through neglect of these precautions it can result in severe functional disability. This is particularly the case when the hips are involved and develop flexion contractures in addition to the spinal deformity. Relief may be obtained by replacement arthroplasty of both hips to restore an upright stance. In a few patients where this fails it may be necessary to undertake a corrective wedge osteotomy of the spine in the lumbar region followed by internal fixation (Fig. 13.21). This is high-risk surgery and should only be performed by surgeons experienced in the procedure.

SCHEUERMANN’S KYPHOSIS (Adolescent vertebral osteochondritis; adolescent kyphosis)

Formerly termed osteochondritis, Scheuermann’s disease¹ is now regarded as unrelated to osteochondritis juvenilis p. 130 and should no longer be so called. Basically, it seems to be an intrusion of part of the intervertebral disc into the vertebral end plate at multiple levels, mostly in the thoracic region. This leads to a rounded kyphosis. The cause and precise nature of the affection are uncertain. It is uncommon.

Pathology. The vertebral bodies ossify from three centres – a primary centre for the middle of the body, and secondary centres for the upper and lower surfaces. These secondary centres, known as the ring epiphyses, appear at about the time of puberty in the cartilaginous end plates that separate the vertebral bodies from the adjacent intervertebral discs. In Scheuermann’s disease there is a disturbance of the normal development of the cartilage plates and ring epiphyses, possibly because they are damaged by bursting of the disc contents through the cartilage into the subjacent vertebral body (Fig. 13.22A). The changes occur predominantly near the anterior margins of the vertebrae, where the greatest weight-thrust is borne. In consequence the disc is somewhat narrowed anteriorly, and through deficient growth of the affected part of the ring epiphysis the vertebral body becomes slightly wedge-shaped (Fig. 13.22B). The deformity predisposes to the later development of osteoarthritis.

Fig. 13.22 Scheuermann’s vertebral kyphosis. A In the active stage the upper and lower margins of the vertebral bodies are irregularly indented in front, and the corresponding parts of the ring epiphyses appear isolated. B Radiograph of the lower part of the thoracic spine of a man aged 20 with established kyphosis from wedging of affected vertebrae.

Characteristically Scheuermann’s disease affects several vertebrae in the thoracic region. Occasionally similar changes are confined to a single vertebra, and this localised form of the disease is as common in the lumbar as in the thoracic region.

Clinical features. The patient is usually 13 to 16 years old, and more often a boy than a girl. In the active stage there is pain in the thoracic spine, with ‘round’ back. After some months the pain subsides, leaving a rounded kyphosis of varying severity (Fig. 13.23A). In later life there may be renewed pain from the development of osteoarthritis. On examination there is a slight or moderate rounded kyphosis in the thoracic region. In the active stage there is tenderness on firm palpation over the affected vertebrae.

Fig. 13.23 A Established Scheuermann’s kyphosis, showing the characteristic curvature. B The late effect of Scheuermann’s adolescent kyphosis: slight wedging of several thoracic vertebral bodies with consequent rounded kyphosis and marked spurring of the contiguous corners of the vertebral bodies anteriorly, denoting osteoarthritis.

Radiographic features. In the active stage of the disease the affected vertebral bodies show deep notched defects at their anterior corners, and the corresponding parts of the ring epiphyses may be irregular in shape and size (Fig. 13.23B). The disc spaces are slightly narrowed but never totally destroyed. After healing, there is slight antero-posterior wedging of the affected vertebral bodies. Years later, osteoarthritic spurring of the anterior vertebral margins is observed, probably as a result of the vertebral malalignment (Fig. 13.23B).

Diagnosis. In its characteristic form the affection is easily diagnosed from the history, clinical appearance, and radiographs. If localised to a single vertebra it may easily be confused with tuberculous spondylitis. Radiologically, the chief points of distinction are that in osteochondritis the margins of the notched defect in the vertebral body tend to be sclerotic rather than rarefied, and a paraspinal abscess shadow (almost a constant feature of thoracic spinal tuberculosis) is never seen. Furthermore, the erythrocyte sedimentation rate is not raised in Scheuermann’s kyphosis.

Course and prognosis. The affection is self-limiting, the active stage lasting for one or two years. If the epiphyses become deformed, permanent wedging of the affected vertebrae, with consequent slight or moderate kyphosis, remains as a cosmetic blemish. Osteoarthritis often supervenes in later life but it is not of major significance clinically.

Treatment. In a mild case treatment is often unnecessary. If pain is troublesome, support for the spine in extension, by a brace or plaster jacket, may be advisable. Bracing may have to be continued for up to six months, according to progress. Meanwhile active exercises to strengthen the posterior spinal muscles are encouraged. In the worst cases – a small minority – operative correction may be considered. Operation entails excision of intervertebral discs, with interbody grafting, in the affected region of the spine, and it usually entails posterior instrumentation to provide correction and stability. It is a major procedure and clearly must not be undertaken without very careful assessment of every facet of the problem, since at best only 40% of the deformity can be corrected.

CALVÉ’S¹ VERTEBRAL COMPRESSION (Vertebra plana; vertebral osteochondritis)

Whereas in Scheuermann’s disease it is the vertebral ring epiphyses that are affected, Calvé’s disease affects the central bony nucleus of a vertebral body. It is generally confined to a single vertebra. It is uncommon.

Pathology. From its radiological features and benign course, Calvé’s disease was regarded as an osteochondritis. Histological studies have shown that the majority of cases are in fact caused by an eosinophilic granuloma p. 72.

In a typical case the bony nucleus of one of the vertebral bodies, usually in the thoracic region, becomes soft and is condensed into a thin wafer. Later, this may re-develop to a more normal size though it is doubtful if it is ever restored to full height. The intervertebral discs above and below are intact and unaffected.

Clinical features. The affection occurs in children of 2 to 10 years of age. The complaint is of pain, usually in the thoracic region of the spine. On examination, there may be slight localised kyphosis. Percussion of the spinal column reveals deep tenderness in the affected region. Movements of the spine as a whole are impaired little, if at all.

Radiographic features. Radiographs show the characteristic extreme flattening of the affected vertebral body, which appears greatly increased in density (Fig. 13.24): it has been likened to a coin seen end on.

Fig. 13.24 Calvé’s disease of vertebral body. The bony nucleus has shrunk into a thin dense wafer. The adjacent intervertebral discs are intact. The usual cause is eosinophilic granuloma.

Treatment. Calvé’s disease is non-progressive, and in practice treatment is required only for as long as the symptoms last. If pain is severe the child should be kept recumbent in bed, but in most cases he may safely resume an active life without external support within a few weeks.

PROLAPSED LUMBAR INTERVERTEBRAL DISC

Herniation of part of a lumbar intervertebral disc is a common cause of combined back pain and sciatica.

Cause. Prolapse of a disc is often precipitated by injury, but it may also occur in the absence of any remembered injury. Spontaneous age-degeneration of the disc is probably an important predisposing factor.

Pathology. The discs between L5 and S1 and between L4 and L5 are those most often affected. Part of the gelatinous nucleus pulposus protrudes through a rent in the annulus fibrosus at its weakest part, which is postero-lateral (Figs 13.25 and 13.26); or sometimes the torn annulus itself protrudes backwards. If it is small, the protrusion bulges the pain-sensitive posterior longitudinal ligament, causing pain in the back. If it is large, the protrusion herniates through the posterior ligament and may impinge upon an issuing nerve to cause sciatic pain. The nerve affected is that which leaves the spinal canal at the interspace next below the site of the disc lesion. Thus the first sacral nerve is impinged upon by a prolapse between L5 and S1, the fifth lumbar nerve by a prolapse between L4 and L5, and so on. Natural healing is by shrinkage and fibrosis of the extruded disc material; not by its reposition within the disc.

Fig. 13.25 A normal intervertebral disc seen in sagittal section (left) and in horizontal section (right).

Secondary effects. Progressive degeneration of the disc leads, after months or years, to altered joint mechanics, with ultimate involvement of the posterior intervertebral (facet) joints as well as the central (body-to-body) joints.

Clinical features. In a typical case of disc prolapse at the L4–L5 or L5–S1 level the clinical picture is clearly defined. The patient is aged between 18 and 60. A few hours or days after jarring or straining the back he or she is seized, while twisting, stooping, or coughing, with agonising pain in the lumbar region. Any movement of the back is impossible. The acute pain gradually lessens in severity, but after a few days a radiating pain is felt in one or other buttock and down the back or side of the thigh to the calf and foot. Tingling or numbness is felt in the calf or foot. The pain is aggravated by coughing or sneezing.

On examination the patient with a fully developed acute attack stands either with a lumbar scoliosis (sciatic scoliosis) (Fig. 13.27) or with the normal anterior lumbar curve obliterated. Forward flexion is greatly restricted, as also may be extension. Lateral flexion, on the other hand, is usually free and painless – certainly to one side if not to both. Straight leg raising is restricted on the affected side, usually markedly – an important clinical sign. Careful tests may reveal slight muscle wasting or weakness in the distribution of the affected nerve, and the corresponding tendon jerk (knee jerk in L3–L4 lesions; ankle jerk in L5–S1 lesions) is impaired or absent.

Fig. 13.27 Sciatic scoliosis in a patient with prolapsed intervertebral disc. There is a temporary list to the left, assumed involuntarily to reduce the pressure on the trapped nerve at the site of the prolapse.

Variations. Atypical cases are common. Thus a definite history of injury or strain is often lacking. The pain may begin gradually rather than suddenly. The symptoms may be confined to the back and never radiate to the lower limb (acute lumbago). On the other hand, the pain is sometimes felt predominantly in the limb and is relatively mild in the back. The severity of the pain varies greatly from case to case, and its exact distribution depends upon the level of the disc prolapse: for instance, in the relatively uncommon cases of mid-lumbar (L3–L4) prolapse the pain radiates towards the groin and the front of the thigh rather than to the back of the thigh and leg.

In a severe case in which the prolapse is almost central there may be pressure upon the cauda equina, with consequent loss of bladder sensibility and retention of urine. This is the dangerous cauda equina syndrome, which must be regarded as an acute surgical emergency, for in the absence of immediate effective treatment serious permanent disability is likely to ensue (see below, p. 241).

Imaging. Radiographic features. In a case of acute prolapsed disc plain radiographs do not show any abnormality, and the purpose of radiography is mainly to exclude other causes of back pain and sciatica. It is only when a disc has been deranged for many months or years that appreciable narrowing of the disc space and spurring of the joint margins, denoting secondary degenerative arthritis (osteoarthritis), are observed.

Magnetic resonance imaging (MRI scanning) can show the intervertebral disc substance and the nerve roots: the bulging disc material can thus be visualised directly, particularly on sagittal projection (Fig. 13.28). Discography has only an occasional place as a diagnostic tool to confirm the level of symptomatic disc disease.

Fig. 13.28 A and B Magnetic resonance images showing herniation of an intervertebral disc at the L5–S1 level. The indentation of the anterior aspect of the cauda equina is clearly seen in the sagittal plane and the postero-lateral protrusion of disc material confirmed in the transverse image.

Correlation of pathology with clinical features. The initial injury or strain marks the time when the annulus fibrosus is torn or damaged. The nucleus pulposus is very gelatinous and an interval elapses before it becomes extruded. Bulging of the extruded material beneath the posterior longitudinal ligament corresponds to the stage of acute back pain. Herniation through the ligament with impingement against the adjacent nerve is responsible for the radiating limb pain and, in low lumbar lesions, the restriction of straight leg raising.

Diagnosis. Prolapsed intervertebral disc must be differentiated from other causes of pain in the back or leg (Fig. 13.29). A dramatically sudden onset is always suggestive of a mechanical derangement and especially of a prolapsed disc, whereas pain that increases relentlessly without intermission suggests a progressive lesion, inflammatory or neoplastic. Although the clinical features are often highly suggestive, definitive diagnosis rests upon appropriate imaging, preferably by magnetic resonance scans.

Treatment. Conservative treatment is successful in relieving the symptoms in a high proportion of cases – probably at least nine out of ten, though most of this improvement may be the result of natural healing. Prolonged bed rest, other than for a few days when symptoms are most acute, should be avoided. The patient should be encouraged to mobilise but the lumbar spine may be supported with a moulded plastic jacket or a well-fitted spinal orthosis (Fig. 13.30). The patient should be encouraged to discard the support as soon as the severe pain has subsided and mobilise the spine with physiotherapy supervision.

Fig. 13.30 Reinforced surgical corset used for mild cases of prolapsed intervertebral disc and for certain types of chronic low back pain.

Intradiscal injection of chymopapain. Chymopapain is an enzyme with the property of dissolving fibrocartilaginous tissue. Injected into the disc substance, it causes partial dissolution of the nucleus pulposus and, in a favourable case, of protruding disc material. This treatment was popular for a few years but has now been discarded because of the risk of nerve damage due to leakage of the enzyme into the spinal canal. In the long term there is marked narrowing of the disc space as seen radiologically. Intradiscal injection of chymopapain is a method of treatment that has been slow in gaining acceptance, largely because the potential dangers were not at first fully assessed. It may be used in selected cases as a possible alternative to excision of the disc, with the advantage that operation is avoided. In most reported series the success rate in cases that would otherwise entail operation is in the order of 80%. Rarely, inadvertent leakage of the enzyme into the spinal canal has led to nerve damage and even death, but when the method is used with proper skill and with due precautions the risks are probably no greater than those of operation.

Operative treatment. Excision of the displaced disc material, or discectomy, is indicated in the following circumstances:

At operation the disc is exposed from behind by retraction of the posterior spinal muscles away from the midline, excision of the ligamentum flavum and perhaps part of a lamina at the appropriate level, and gentle retraction of the theca. The protruded part of the disc forms an obvious rounded bulge, over which the emerging spinal nerve may be seen tightly stretched. The extruded material is removed, together with as much of the remaining nuclear tissue as can be pulled out from between the vertebral bodies. Many surgeons now favour excision by a magnification technique, the so-called ‘microdiscectomy’, utilising the operating microscope through a limited interlaminar approach using a small ‘stab’ incision. This obviates the need for extensive stripping of muscles from the back of the spinal column and reduces the associated post-operative morbidity, allowing the patient a more rapid return to normal activity.

ACUTE LOW BACK PAIN (LUMBAGO)

Back pain is a symptom rather than a disease. In a typical acute attack the patient is suddenly seized with agonising pain in the lumbar region of the spine, usually while stooping, lifting, turning, or coughing. The pain is often so severe that any movement is difficult and the patient is ‘stuck’. With rest, the pain gradually subsides, but in some cases the acute back pain is accompanied by sciatica, suggesting irritation of a lumbar or sacral nerve.

The pathogenesis of acute low back pain is not entirely clear. Indeed there may be more than one cause. Probably in many cases the underlying lesion is a prolapsed disc that has not yet been retropulsed far enough to interfere with a nerve root (Fig. 13.26B). It is in these cases that sciatica may develop later, as the size of the prolapse increases. But other examples of acute back pain are more convincingly ascribed to some other mechanical fault, such as sudden nipping of synovial membrane in one of the facet joints, or momentary subluxation at an intervertebral joint that is unstable on account of disc degeneration or degenerative arthritis. Nerve irritation may also be the result of leakage of inflammatory cytokines from the degenerative lumbar disc. In most cases acute attacks of pain may recur at intervals of months or years, with intervals of relative freedom between the attacks.

Treatment should be conservative and similar to that used for prolapsed lumbar intervertebral disc. Mobility should be maintained and prolonged bed rest discouraged. Mobilisation and postural retraining under physiotherapy supervision has been shown to be beneficial.

SPONDYLOLYSIS

In spondylolysis there is a defect in the neural arch of the fifth (rarely the fourth) lumbar vertebra. There is loss of bony continuity between the superior and the inferior articular processes, the deficiency being bridged by fibrous tissue (Fig. 13.31). If this stretches or gives way, the consequent vertebral displacement constitutes one variety of spondylolisthesis (see below).

Fig. 13.31 Site of the defect in spondylolysis. There is lack of bony continuity at the isthmus of the neural arch (pars interarticularis) on each side.

Though the defect was formerly regarded as congenital it is now widely believed that it may be caused by injury; or, more specifically, it may be the result of a stress fracture in childhood or adolescence.

Clinically, spondylolysis (the defect without displacement) is often symptomless, but it is sometimes a cause of deep lumbar back pain. Radiographically, the defect is usually best shown in oblique projections or on a CT scan.

Treatment. This is often unnecessary. Aching may be relieved by a surgical corset or belt. If pain is unusually troublesome an attempt may be made to close the defect in the pars interarticularis on each side by transfixing it with a screw and laying in slender bone grafts; or alternatively, local fusion of the spine may be undertaken (see p. 245).

SPONDYLOLISTHESIS (Lumbar spondylolisthesis)

Spondylolisthesis is the term applied to spontaneous displacement of a lumbar vertebral body upon the segment next below it. Displacement is usually forwards: only rarely does backward displacement occur (retrospondylolisthesis).

Cause. There are three predisposing factors leading to spondylolisthesis of three distinct types:

Pathology. In the normal spine forward displacement of a vertebral body is prevented by engagement of its articular processes with those of the segment next below it. In spondylolisthesis there is a failure of this check mechanism, and the attachments of the intervertebral disc alone are not strong enough to hold the vertebral bodies in alignment.

In the first type of spondylolisthesis, the least common, there is a congenital basis for the displacement. The posterior intervertebral joints are unstable because the articular processes are congenitally malformed or even rudimentary: thus they form no bar to forward displacement of the spinal column (Fig. 13.32). This defect occurs most often at the lumbo-sacral joint. Displacement may be severe and, since the whole vertebra is displaced complete with its neural arch, the cauda equina may be trapped, with consequent severe neurological disturbance (Fig. 13.32).

Fig. 13.32 (Left) Spondylolisthesis secondary to congenital malformation of the articular processes at the lumbo-sacral joint. The cauda equina is trapped between the body of the sacrum and the lamina of the displaced fifth lumbar vertebra. In this type of spondylolisthesis neurological signs are to be expected.

In the second type, which is the best recognised, a defect in the neural arch of a vertebra allows separation of its two halves (see spondylolysis, and Fig. 13.33). The body, with the pedicles and superior articular processes (and the whole of the spinal column above it), slips forwards, leaving behind the laminae and inferior articular processes (Fig. 13.33). The fifth lumbar is the vertebra usually affected, the fourth occasionally. Displacement may gradually increase, especially during adolescence, and it sometimes reaches a severe degree. There may be minor irritation of one of the issuing nerves, with consequent sciatica; but despite severe bony displacement serious interference with the nerves of the cauda equina is exceptional in this type of spondylolisthesis.

Fig. 13.33 (Middle) Spondylolisthesis due to defect of the neural arch of a vertebra, in this case affecting the fifth lumbar vertebra. The body and superior articular processes have slipped forwards, leaving the spinous process and inferior articular processes in normal relationship with the sacrum. (Radiographically the defect is seen best in oblique projections.)

In the third type of spondylolisthesis (sometimes termed pseudospondylolisthesis), seen fairly commonly, the arthritic posterior intervertebral facet joints become unstable with degeneration of the articular cartilage and osteophyte formation displacing the joint surfaces (Fig. 13.34). It may occur at any level in the lumbar spine—most commonly between the fourth and fifth lumbar vertebrae. In this type the vertebral displacement is occasionally backwards rather than forwards (see Fig. 13.17), but in either case displacement is never severe, and neurological disturbance is unusual.

Fig. 13.34 (Right) Spondylolisthesis secondary to osteoarthritis. Wearing down of the cartilage of the posterior intervertebral (facet) joints has permitted slight forward displacement of the fourth lumbar vertebra on the fifth. The condition may occur at any level in the lumbar spine.

The intervertebral disc at the site of vertebral slipping is inevitably damaged, and disc prolapse may occur.

Clinical features. The clinical features of spondylolisthesis are inconstant: they depend to some extent upon the nature of the causative lesion and upon the degree of displacement. Thus in spondylolisthesis from under-development of the articular processes (Fig. 13.32), and in that from a defect of the pars interarticularis (Fig. 13.33), the patient is usually a young adult, whereas displacement from degeneration of the facet joints in osteoarthritis (Fig. 13.34) is seen characteristically in patients beyond middle age. In some cases the deformity is entirely symptomless. When symptoms occur they take the form of chronic backache, with or without sciatica. The back pain is worse on standing.

On examination there is often a visible or palpable ‘step’ above the sacral crest, due to the forward displacement of the spinal column; but this is obvious only when the displacement is severe. Spinal movements are restricted only slightly, if at all. Abdomen: When displacement is severe the spinal column is projected forwards and the lumbar vertebral bodies may be palpable through the abdominal wall. Lower limbs: Minor irritation of a sciatic root is often evidenced by impairment of straight leg raising; but severe neurological disturbance is seldom observed except in the rare cases in which congenital malformation of the articular processes allows dislocation of the whole vertebra complete with its neural arch (Fig. 13.32).

Radiographic features. Lateral and oblique views will sometimes demonstrate a defect of the neural arch (Fig. 13.35), but CT scans will show this more clearly (Fig. 13.36).

Fig. 13.35 Oblique radiograph of the lower lumbar region of a patient with spondylolisthesis, showing a defect of the pars interarticularis of the neural arch of the fourth lumbar vertebra (centre of illustration). Oblique radiographs such as this are important in the differentiation of spondylolisthesis caused by a neural arch defect from the other two types of spondylolisthesis.

Fig. 13.36 Sagittal CT scan of lumbar spine to show a defect in the pars interarticularis of the L5 vertebra (arrow). This has led to a forward slip of the L5 vertebra on the sacrum.

Treatment. When spondylolisthesis is symptomless treatment is not required.

Non-operative treatment. Moderate symptoms are often adequately relieved by a well-fitted surgical corset and this should be tried before operation is considered.

Operation. This is justified only when the disability (from back pain or neurological disturbance) is severe. The operation entails the release of stretched or compressed nerves, followed by fusion of the affected segments of the spinal column. Fusion of the spine is normally achieved by bridging the vertebrae with bone grafts, usually obtained from the ilium, though sometimes allograft bone may be used. In posterior fusion the grafts are fitted between or alongside the spinous processes, superficial to the laminae. In anterior fusion blocks of bone are inlayed in deep slots cut in the vertebral bodies after excision of most of the intervertebral disc from the front. In lateral fusion bone grafts are wedged between the transverse processes or, in the case of the lumbo-sacral joint, between transverse processes above and the lateral masses of the sacrum below. Each method has its special application, but the choice also depends largely on the nature of the pathology to be treated and the surgeon’s individual preference.

SPINAL STENOSIS (Claudication of the cauda equina)

In the syndrome of spinal stenosis standing and walking beyond a certain duration are associated with increasingly severe pain in the gluteal region and lower limb on one or both sides, ascribed to cramping of nerves and their blood vessels in a constricted spinal canal.

Pathology. The dimensions of the spinal canal in the lumbar region show considerable variation between individuals. The cross-sectional shape of the canal also varies, it being sometimes rounded and sometimes almost triangular. Thus in some persons there is a congenital narrowing or constriction of the canal which, though providing adequate room for the cauda equina in the absence of other pathology, nevertheless allows little or no margin of safety, so that if the canal becomes further narrowed from secondary causes such as the formation of osteophytes about the facet joints, or bulging of an intervertebral disc, the normal functioning of nerves of the cauda equina will be impaired by lack of room and constriction of their blood supply. To some extent the constriction seems to be selective rather than uniform throughout the cauda equina, the nerves lying in the narrow lateral recesses of a triangular canal being particularly vulnerable. For a long time the impairment of nerve function is intermittent rather than permanent, being rapidly reversible when the patient assumes a sitting posture.

Clinical features. The clinical history is characteristic. The patient, often an elderly man, complains that after walking for a matter of 10–15 minutes, he develops a heavy aching sensation in one or both lower limbs, and that this steadily increases to such an extent that eventually he is forced to sit down. In most cases similar symptoms develop when the patient stands for a while, even without walking. Relief is obtained only by sitting or by lying with the hips and knees drawn up in a sitting posture: it is not sufficient just to stop walking. Sitting relieves the symptoms within a few minutes because on flexion of the spine the canal is widened, and the patient can then resume walking or standing for a further period.

Examination may reveal little abnormality, though frequently there are features to suggest degenerative change in the lumbar spine – for instance impairment of spinal mobility.

Imaging. Plain radiographs may give the impression that the spinal canal is narrower than usual and they may show further constriction of the canal by posterior osteophytes upon the margins of the vertebral bodies or in relation to the facet joints. Magnetic resonance imaging (MRI) shows very clearly the shape of the spinal canal, and may also show bony or soft-tissue outgrowths encroaching upon either a normal or a congenitally constricted canal (Fig. 13.37).

Fig. 13.37 A Sagittal and B axial MR scans of lumbar spine in spinal stenosis. There is marked narrowing of the spinal canal at the L4–L5 level, in part due to the bulging disc, though much of the compromise is from the posterior aspect by the ligament flavum which is buckled and hence appears thickened.

Diagnosis. The spinal stenosis syndrome bears superficial resemblance to intermittent claudication from vascular disease. Confusion should be avoided, however, because of the important distinction that pain in spinal stenosis, unlike that from arterial disease, comes on not only with walking but also with standing, and is relieved only by sitting or by flexing the spine. Moreover, examination of the vascular system shows no abnormality.

Treatment. Mild symptoms may be controlled by appropriate modification of activities – for instance by using a bicycle instead of walking, and by the avoidance of prolonged standing. In the fully established case with severe intractable symptoms, treatment should be by operation to decompress the spinal canal by removal of intruding osteophytes and enlargement of the lateral recesses at the level of the constriction. Decompression may have to be carried out over a number of segments, depending upon the longitudinal extent of the constriction as shown by appropriate imaging.

TUMOURS OF THE TRUNK AND SPINE

TUMOURS IN RELATION TO THE SPINAL COLUMN, SPINAL CORD, OR EMERGING NERVES

Classification and pathology. As in the cervical region, tumours involving the spine or related nerves may arise:

1 in the bony spinal column itself

2 in the meninges or, rarely, the spinal cord

3 in the fibrous component of a peripheral nerve (neurofibroma)

4 in adjacent soft tissues.

Tumours of the spinal column may be benign (for instance chondroma, giant-cell tumour, haemangioma, osteoblastoma) but are more often malignant. Such tumours may be primary (sarcoma, multiple myeloma, chordoma), but metastatic tumours predominate. A meningeal tumour (meningioma) is an occasional cause of compression of the spinal cord or cauda equina. Nerve compression may also be a consequence of a neurofibroma growing within the spinal canal.

Clinical features. The effects of these tumours vary according to their site and character. Broadly, the effects may be placed in three groups:

Local destruction of the skeleton. The commonest cause is a malignant tumour of the bones of the spinal column (Fig. 13.38) – usually a metastatic carcinoma. The predominant symptom is pain, which is constant and increases relentlessly in its severity. Frequently there are associated neurological manifestations from involvement of the spinal cord or nerve roots. Sometimes deformity, from collapse of the bony structure, is evident clinically; or there may be marked restriction of spinal movement, with protective muscle spasm.

Fig. 13.38 Partial collapse of the second and fourth lumbar vertebrae in a patient with myelomatosis. Note that the intervertebral discs are not destroyed.

Compression of the spinal cord. This may occur from tumours of the spinal cord itself or of its meninges, from tumours of nerves (neurofibroma), or from tumours of the bony spinal column. The clinical manifestations depend upon the exact location of the tumour. Typically, when the spinal cord is slowly compressed, initial root pain (girdle pain in thoracic involvement, lower limb pain in lumbar involvement) is followed by lower motor neurone paresis at the segmental level corresponding to the site of the tumour, by progressive sensory and upper motor neurone paralysis below the lesion, and often by bladder or bowel dysfunction.

Interference with peripheral nerves. Peripheral nerves – especially the nerves of the cauda equina – may be involved by tumours of the nerves themselves (neurofibroma), by tumours of the spinal column (benign or malignant), or by tumours in the peripheral course of the nerves (for example, a tumour of a rib, or a tumour arising from or within the pelvis). The clinical features depend upon the particular nerve or nerves affected and upon the extent of the involvement. Typically, there will be constant, progressive, and ultimately severe pain along the course of the affected nerve, with sensory impairment, increasing motor weakness, and depression of reflexes in the distribution of the nerve. Retention of urine is usually a prominent feature of a tumour interfering with the cauda equina.

Imaging. Plain radiographs will usually help in discovering a tumour arising in the bones of the spinal column (Fig. 13.38), or eroding the bone from outside. In cases of vertebral destruction by a tumour the adjacent intervertebral discs are typically preserved. This point helps in the distinction from erosion and collapse due to infection, in which the discs are destroyed at an early stage (compare Figs 13.13A and 13.38).

Radiographs of the chest may reveal a primary lung tumour or a metastasis; and radiographs of the rest of the skeleton may be helpful in the diagnosis of disseminated tumours. Magnetic resonance imaging is indispensable in showing the full extent of the tumour and the extent to which the adjacent tissues have been infiltrated (Fig. 13.39).

Fig. 13.39 A and B Sagittal T1 and T2 weighted MR scans of spinal metastasis. The T12 vertebra is replaced by abnormal marrow signal and there is some collapse with retropulsion of tissue into the spinal canal, features typical of a metastatic deposit in the spine.

Radioisotope scanning may show evidence of a lesion before it is evident radiographically. CT scanning is capable of showing even quite small tumours within the vertebrae.

Diagnosis. The possibility of a tumour has to be borne in mind constantly in the differential diagnosis of back pain and lower limb pain, especially when associated with radiological signs of vertebral erosion or collapse or with neurological disturbance affecting the trunk, lower limbs, or viscera (Fig. 13.29).

A history of insidious onset, with relentless increase of symptoms without remission, always suggests the possibility of tumour. Careful search should always be made for a primary tumour elsewhere in the body.

Treatment. This is dependent on the site and nature of the tumour, but it should be remembered that many of these patients will survive for a considerable period of time and may require more active treatment than analgesic therapy alone for their increasing pain. Radiotherapy to the bone lesions and sometimes operative spinal decompression and fusion may be required in selected cases.

CHRONIC LOWER LUMBAR LIGAMENTOUS STRAIN (Postural back pain)

The terms chronic ligamentous strain and postural back pain are used to cover an ill-defined group of affections characterised by persistent backache without demonstrable pathology. These conditions are common – in fact they form a considerable proportion of the cases of back pain seen in orthopaedic practice.

Cause. It is assumed that the spinal muscles fail in their function of protecting the deep ligaments in maintaining posture. Predisposing causes include childbirth, overweight, general flabbiness of muscle, and debilitating illness.

Pathology. No precise lesion is demonstrable.

Clinical features. The pain is characteristically in the lumbar or lumbo-sacral region. It tends to be worse on activities such as stooping, or after prolonged standing or sitting in one position. On examination there may be no abnormal physical signs but in many cases there is some restriction of spinal movement. Radiographs are normal.

Diagnosis. This depends upon the exclusion of demonstrable pathological lesions by careful clinical and radiographic examination. A history of long-continued lumbar backache, with a total lack of clinical or radiological abnormalities, should always suggest this group of affections.

Course and prognosis. Aching often persists intermittently for many years despite treatment. Nevertheless in most cases the condition is a source of nagging discomfort rather than a serious handicap to most ordinary day-to-day activities.

Treatment. Often reassurance alone is required. Treatment may be required for short-term exacerbations, but should be focused on activity modification, weight loss, active exercises to strengthen the spinal muscles and postural correction under physiotherapy supervision. Other more invasive treatments such as local injections of anaesthetic solution or hydrocortisone should be avoided if possible.

COCCYDYNIA

In its widest sense, coccydynia includes any painful condition in the region of the coccyx. In practice, the term is restricted to the clinical entity in which persistent pain continues for many weeks or months after a local injury, despite the absence of demonstrable pathology. Eventually it is a self-limiting affection, but it may cause severe discomfort while it lasts – often for many months.

Cause. Typically coccydynia develops after an injury – usually a fall on the ‘tail’. Occasionally a history of injury is lacking.

Pathology. In some cases there is probably a strain of the sacro-coccygeal joint; in others the lesion is thought to be simply a contusion of the periosteum over the lower sacrum or coccyx. Rarely, a crack fracture of the coccyx or sacrum is demonstrated.

Clinical features. There is pain localised to the sacro-coccygeal area, worse when sitting. In severe cases there is also pain on defaecation. Usually the patient is free from pain when standing or lying. On examination there is localised tenderness over the sacro-coccygeal region. In some cases the pain can be reproduced by moving the coccyx. In the absence of a fracture, radiographs do not show any alteration from the normal.

Diagnosis. It is important to consider other causes of pain in this area, especially infections of the sacro-coccygeal joint and tumours of the sacrum or coccyx. Investigation should include rectal examination, and radiographs must always be obtained.

Treatment. In most cases treatment is not required. All that is necessary is to exclude serious organic disease, and then to reassure the patient that the condition is harmless and that it may be expected to resolve spontaneously if left alone. In resistant cases manipulation and local injection of steroids have been used but none of these methods is uniformly successful. In unusually severe and persistent pain surgical excision of the coccyx may be required.

OSTEOPOROSIS

The vertebrae of the thoracic and lumbar spine are one of the commonest sites affected by osteoporosis, or so-called ‘brittle bone’ disease. This is a general affection of the skeleton and is described in more detail on page 81. It is commonest in postmenopausal women, but it can also affect men in the same age group. Its onset is insidious, but crush fracture of the vertebral body is the commonest of the fragility fractures associated with this condition. Its onset may be associated with an episode of minor trauma, but there is often no significant injury and only minor local pain. More commonly, the patient presents with progressive loss of height and an increasing kyphotic deformity of the thoracic spine. This results from collapse of the thoracic vertebrae at several levels with anterior wedging of the bodies (Fig. 13.40). In advanced cases the radiographs show little difference between the density of the bone and the intervertebral discs.

Fig. 13.40 Lateral radiograph of osteoporotic spine in an elderly female patient. There are multiple vertebral fractures with collapse in the mid thoracic region resulting in a rounded kyphotic deformity.

Treatment. Greater awareness of the morbidity of this condition in a rapidly increasing elderly population has led to more active medical and surgical interventions. All patients should be investigated to determine the cause and extent of their bone loss and, where appropriate, medical treatment instituted to prevent further progression. In selected cases where local pain is more severe and of recent onset, a new minimally invasive surgical treatment of balloon kyphoplasty may be considered. Using radiographic screening a percutaneous probe is inserted into the centre of the collapsed vertebral body and is then replaced with a balloon-like device which is inflated with contrast medium until the vertebral body height is restored. Finally the space is injected with semi-liquid polymethylmethacrylate cement which once solidified will restore the vertebral bone stability.

EXTRINSIC DISORDERS SIMULATING SPINAL DISEASE