BY GABRIEL ISAAC OTUK
There are various situations that result in harm or injury to the spine, causing it to curve to the side. This deformity may be structural, implying a permanent change in the bone or soft tissues; or it may be no more than a temporary disturbance, produced by reflex or posture activity of the spinal muscles.
The medical term for the curving of the spine to the side is scoliosis. The various types of scoliosis include: infantile scoliosis, primary or ‘idiopathic’ structural scoliosis, secondary structural scoliosis, compensatory scoliosis, and sciatic scoliosis.
Infantile scoliosis begins in the first year of life as a simple curve, and is usually a convex curve to the left. There is no known cause of it.
Idiopathic structural scoliosis begins in childhood or adolescence and tends to increase progressively until the cessation of skeletal growth. Sometimes, it leads to deformity, especially when the thoracic region is the part affected. The condition is more common in girls than in boys. Recent evidence has suggested a genetic link with the disorder and several candidate genes are currently under investigation.
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.
Clinical features of idiopathic structural scoliosis
In children, deformity is usually the only symptom and pain is occasionally a feature in adults with long-standing deformity, particularly with structural curves in the lumbar region of the spine.
The outlook depends on the age. The ultimate visible deformity tends to be worst in thoracic scoliosis and least in lumbar scoliosis.
Assess the prognosis for progression of the deformity from a consideration of the age, site and severity of the curve. This will require 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 (picture in which the pass is front to back) of the spine. When the prognosis is good (for instance, in most cases of lumbar scoliosis), treatment, should be regular. Clinical and radiological reviews every six months may be all that is required.
However, when the prognosis is poorly done, active treatment is advised. This usually necessitates operation, and much surgical endeavour.
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 can be used.
The Milwaukee brace is the most common. Here, correction is done 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.
Here, the spinal curvature is secondary to a demonstrable underlying abnormality.
Causes include congenital abnormalities (especially hemivertebra), poliomyelitis (often called polio or infantile paralysis) with residual weakness of the spinal muscles (paralytic scoliosis), and neurofibromatosis which is a genetic disorder that causes tumours to form on nerve tissue. In congenital hemivertebra, there is a sharp angulation at the site of the anomaly, with compensatory curves above and below.
Visible deformity is the only symptom. The age of onset, site, nature, and severity of the curve varies with the underlying cause. 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.
For instance, when the lower limbs are unequal in length, or when there is a fixed abduction 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. 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, the pathogenesis of which is not entirely clear.
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. Severe back pain or sciatica, aggravated by movements of the spine. The onset is usually sudden. The scoliosis is poorly compensated; so the trunk may be tilted over markedly to one side. The curvature is not associated with rotation of the vertebrae.
The author is an orthopaedic specialist