Trunk and spine

13 Trunk and spine


Pain in the back is the commonest symptom encountered in orthopaedic practice. Indeed, if accident cases are excluded, it probably accounts for nearly a third of all orthopaedic out-patient attendances.


When this huge mass of material is sifted and categorised it is found that the cases fall into two broad groups. In the first group clear-cut physical signs, with or without distinctive radiographic changes or other abnormal findings, allow a precise determination of the nature of the lesion and of its site. The diagnosis is positive, and rational treatment can be applied. In the second group, almost as large as the first, there are few or no abnormal findings on clinical examination or from imaging investigations; so the pathology is unclear. Diagnosis is largely a matter of conjecture, and treatment is empirical. For want of more accurate knowledge these rather vague and unsatisfactory cases are generally classed as ‘chronic ligamentous strain’ or ‘postural back pain’.


Lumbar back pain is often accompanied by radiating pain in the buttock, thigh, or leg, usually on one side but occasionally on both sides. This pain is generally referred to as sciatica, though the term should strictly be reserved for pain in the distribution of the sciatic nerve. It should be noted that sciatica is often a much more disturbing and persistent symptom of back disorders than the back pain itself, which indeed may be slight or transient.



SPECIAL POINTS IN THE INVESTIGATION OF BACK AND SCIATIC SYMPTOMS








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.



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.




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.



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.



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.



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.



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.





CONGENITAL ABNORMALITIES AND DEFORMITIES






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:









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).



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.



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.



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.


image image

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.








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).

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Jun 5, 2016 | Posted by in ORTHOPEDIC | Comments Off on Trunk and spine

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