Spinal deformity

  Scoliosis

This is a lateral curvature of the spine hut is usually accompanied by a rotational deformity as the spinal column starts to buckle and shorten. In the thoracic region the rotation throws the ribs into prominence producing the cosmetically deforming rib hump (Fig. 28.35a and b) whereas in the lumbar region the same degree of curvature may not be so noticeable. A curve is described as structural or fixed when there is loss of mobility in the involved segment. This usually occurs because of alterations in the shape of the vertebrae and adaptive changes in soft tissues. A curve is mobile when normal flexibility is preserved; such curves are often described as postural although strictly speaking the terms are not interchangeable. A postural curve is secondary to the position of the body, one of the commonest causes being leg-length inequality. Curves are also described on the basis of their anatomical site and whether they are primary (major) or secondary (compensatory) to the primary curve in an attempt to maintain spinal balance.

  The causes of scoliosis are summarised in Table 28.7.

  Idiopathic scoliosis

Idiopathic scoliosis is the commonest type and is usually considered in three sub groups.

Infantile idiopathic scoliosis may be related to sleeping position. It is usually noted between birth and the age of 1 year. It is often a component of the ‘moulded baby syndrome’ (plagiocephaly, tight hip adductors, scoliosis, foot defor­mities). The curves are usually convex to the left and are more common in males. The great majority resolve without treatment but approximately 10 per cent progress and pose difficult problems. Serial examination and radiographs are important to detect progressive cases. Measurement of the rib—vertebra angle difference (Mehta) is helpful in predicting which cases are likely to progress. Treatment is initially by bracing but if unsuccessful there is an indication for anterior release of the affected spinal segments.

Juvenile idiopathic scoliosis. This occurs between the ages of 3 years and puberty. The distinction between juvenile and early adolescent curves is ill defined. However, juvenile curves frequently progress and early bracing is advisable.

Adolescent idiopathic scoliosis is the commonest form and occurs at puberty. It is slightly more common in girls and usually convex to the right. A number of different patterns of curve has been described depending on site and distinguish­ing between the major and compensatory curves. Apprecia­tion of the patterns is important in assessing the extent and level of spinal fusion. In general, treatment is required for all curves that are progressing.

 The following are important factors in assessing progression.

Sex. Progression is more common in girls.

Age. Progression is more likely when there is potential for skeletal growth. Curves presenting before menarche have more potential for progression. Ossification of the iliac apo­physis (Risser’s sign) is helpful is assessing skeletal maturity.

Curve pattern. Double curves are more likely to progress than single thoracic curves which in turn are more likely to progress than lumbar curves.

Curve magnitude. Progression is more likely with curves over 300.

Other factors. Patients with slender spines are more likely to progress.

 Clinical features. The above features related to curve pro­gression must be noted. In addition, a history of pain or neurological symptoms makes it important to exclude other causes of scoliosis such as a spinal tumour. On examination, the site, flexibility and cosmetic effects of the curve are noted, as well as spinal balance, i.e. is the head centred over the natal cleft? A neurological examination should be carried out, skin blemishes, e.g. café au lait patches, should be sought and any leg-length discrepancy measured. The curve can only be assessed accurately by radiology (Fig. 28.36).

Treatment. Idiopathic scoliosis can only he treated by brac­ing and surgery. In general, curves which measure less than 30degree should be managed nonoperatively with regular clinical and radiological assessment. Earlier intervention should be undertaken in those curves with a worse potential. Once there is clear evidence of progression bracing is used for curves between 30degree and 45degreeThere are two main types of brace. The Milwaukee incorporates anterior and posterior struts that support a neck ring and suboccipital pads. The Boston brace is an underarm device constructed from a pelvic module fitted with individualised pads to correct lumbar and thoracolumbar curves. Since it can be worn under clothes it is more acceptable than the Milwaukee but is not suitable for high curves.

Surgery is generally indicated when:

  bracing is likely to be ineffective because

   the curve is too large, i.e. >450

   the site makes it difficult to brace, e.g. high thoracic or true double thoracic curve,

   the curve is fixed;

the curve is deteriorating in a young child;

there is loss of spinal balance;

the cosmetic appearance needs correction.

  The surgical procedures to correct, stabilise and fuse the spine include anterior release, and anterior and posterior instrumentation techniques (Fig. 28.37). Spinal cord monitoring is usually employed during such surgery that aims to produce a balanced, corrected, stable spine with a minimum of fused segments.

Congenital scoliosis

This is usually due to a failure of formation, e.g. hemivertebra (Fig. 28.38) or failure of segmentation, e.g. a bar. Mixed patterns can occur and the anomalies may be single or multi­ple. Associated abnormalities are diastomatomyelia, and cardiac and renal malformations. A unilateral unsegmented bar with a contralateral hemivertebra at the same level along with thoracolumbar anomalies are associated with partic­ularly severe curves. In general, early fusion in situ should be undertaken for curves that are progressing or likely to progress. On occasions, other procedures may be appropriate such as hemivertebra excision or growth arrest operations.

  Neuromuscular scoliosis

  Many neuromuscular conditions such as cerebral palsy, spina bifida, polio and muscular dystrophy can cause a scoliosis. Characteristically a long, C-shaped thoracolumbar curve is found. Left untreated, severe deformities can occur with reduction of respiratory function and great difficulties in nursing. Early bracing is valuable, surgical stabilisation is often necessary and strong internal fixation is necessary to allow early mobilisation.

Tumours

  Turnouts involving the vertebrae, e.g. osteoid osteoma or the neural elements, may present as a scoliosis. Any child presenting with significant back pain should be investigated and a bone scan is a useful screening test.

Other conditions

  Other conditions associated with scoliosis include infections, disc prolapse, spinal injury and skeletal dysplasias such as neurofibromatosis, Marfan’s syndrome and osteogenesis imperfecta.

  Kyphosis

A kyphosis is normally present in the thoracic spine but more than 45degree is considered to be excessive. The deformity may be idiopathic or occur as a result of:

congenital abnormalities such as anterior bony bar;

developmental delay, e.g. cerebral palsy;

vertebral collapse, e.g. infection, osteoporosis, sickle cell disease (Fig. 28.39a—c).

      There is a spectrum of idiopathic scoliosis. In Scheuermann’s disease, the kyphosis is associated with radiological changes such as irregular vertebral end plates, apparent narrowing of the disc space and wedging of one or more vertebrae. These changes make the kyphosis more rigid than the less severe postural round back in which radiographs are normal. Apart from the cosmetic deformity, Scheuermann’s disease may be associated with back pain, especially after skeletal maturity and, in severe cases, brace treatment and occasionally fusion may be justified.