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

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.

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.