In a nonstructural scoliosis no gibbus is observable in the forward bending test. Manifestations of a non-structural scoliosis are postural and compensatory scoliosis.

If present, it is usually seen at the end of the first decade of life. There is a slight, usually left convex thoracic curve. It disappears when the child lies down and can be actively corrected when standing. When bending forwards there is no hump, and the lateral curve disappears completely (Fig. 3.3). This curvature never becomes structural. The lateral curvature disappears spontaneously as the child grows.

A difference in leg length causes a compensatory scoliosis only when standing. The convex side is on the side of the short leg. There is no torsional component. The scoliosis disappears when sitting, when lying down, also after correcting the difference in leg length, and also during the forward bending test (Fig. 3.4). This curvature never becomes structural either.

Manifestations of a structural scoliosis are congenital, idiopathic and neuromuscular.

This scoliosis occurs due to abnormal vertebrae such as hemivertebrae and unilateral nonsegmented bony connections (Fig. 3.5). In 75 % of these cases there is a progressive scoliosis of 5° per year, in 14 % there is slight progression, and only 11 % are non-progressive (Table 3.1). The abnormality occurs usually at the level of the thoracic spine. On physical assessment the scoliosis cannot be distinguished from a progressive infantile or juvenile idiopathic scoliosis (see below). Radiological assessment provides information. Children with a congenital scoliosis often have other abnormalities too (Table 3.2). The most dangerous accompanying abnormalities are congenital cardiac anomalies (5–10 %) and abnormalities of the urogenital system (20 %). In 10 % of cases there is a spinal dysraphia (Table 3.2).

These are developmental disorders in the median line of the back. The most common is spina bifida. Diastematomyelia (Fig. 3.6), tethered cord (Fig. 3.7) and intraspinal lumbosacral lipoma (Figs. 3.8 and 3.9) are also spinal dysraphias. In half of all cases physical assessment shows signs that point to a spinal dysraphia. These can be skin abnormalities in the lower back in the midline such as enhanced hair growth (lumbar hypertrichosis), pigmented or depigmented naevi, port-wine stains, a sacral dimple, (Fig. 3.10) a fistula or a subcutaneous lipoma.

(Latin for split spine). This is a birth defect with an incomplete closing of the spine. There are three types: spina bifida occulta, meningocele and myelomeningocele. The most common location is the lumber spine. The spina bifida occulta has no or only skin signs at physical examination. A meningocele causes a sac of fluid at the gap in the spine. A myelomeningocele is the most severe form associated with hydrocephalus, tethered cord, anomalies of the lower extremities, walking problems and problems with bladder and bowel control.

In a diastematomyelia (diastema is Greek for in-between space) there is a bony, cartilaginous or fibrous partition in the middle of the spinal canal (Fig. 3.6). As a result of traction on the spinal cord, which is fixed at the position of the partition in the spinal canal, pain and progressive neurological symptoms such as urinary problems, gait disorders and foot deformities occur in growing children.

Tethered cord may also described as an attached low medullary cone or a fixed myelum. The lowest cone-shaped end of the spinal cord (medullary cone) normally lies at the level of L3 in newborns and at the L1 or L2 in adults (Fig. 3.7). The distal end of the medullary cone is attached to the distal end of the spinal cord canal by a fibrous band (terminal filum). During growth the lower end of the myelum (spinal cord) does not shift cranially in a tethered cord. Adhesion of the cone often also occurs and the the filum is terminally shortened. During growth progressive neurological symptoms can develop as a result of traction on the spinal cord.

The lipoma can usually be clearly seen as a subcutaneous swelling (Fig. 3.8). The extraspinally located part of the lipoma is often connected with a part located interspinally (Fig. 3.9).

In a congenital scoliosis one should also consider a VACTERL association (V stands for vertebral abnormalities, A for anal atresia, C for cardiac anomalies, T and E for tracheoesophageal fistula, R for renal anomalies such as urethral atresia and renal agenesis, and L for limb defects such as radial aplasia¹).

This is a scoliosis in which the cause is unknown. The curvature may consist of a single or double curvature (S-shaped). The position and direction of the lateral curvature remains unchanged in the course of time, but if the anomaly increases several additional vertebrae may become involved. In single curvatures compensatory curvatures tend to appear, so that the spinal column remains in balance. If there is a loss of balance, misalignment can be assessed using a perpendicular line. Compensatory curves are in principle not structural but can become so with the passage of time.

This is rare and comprises 1 % of all scolioses. It affects boys more often than girls (3:2). The lateral curvature is convex to the left and thoracically localized (Fig. 3.13). Accompanying anomalies may be facial and cranial asymmetry (plagiocephaly), torticollis or developmental dysplasia of the hip. In 85 % of cases the curvature fortunately disappears before the first year of age. Spontaneous disappearance of the curvature never occurs if the curvature is more than 35°. In 15 % of cases the curvature does not disappear spontaneously and a severe deformity is the result (Table 3.1). It is important to make a distinction between nonprogressive and progressive infantile scoliosis. This is best achieved by requesting an anteroposterior X-ray of the spinal column and measuring the ribvertebral angle difference at the top of the curvature (RVAD or Metha angle). The angle between the spinal column and the rib, on both the left and the right sides, is measured. If the difference is more than 20° we are dealing with a progressive infantile idiopathic scoliosis in 90 % of cases. In 10 % of cases the scoliosis will disappear spontaneously (Fig. 3.14). If the RVAD is less than 20° spontaneous disappearance occurs in 90 % and in the remaining 10 % will become progressive. It is prudent to follow-up the child every 4 months radiologically from age 1 to age 2, to determine non-progression or progression.

This involves 10–20 % of all idiopathic scolioses. This type of scoliosis is equally common among boys and girls. It usually involves a right convex thoracic scoliosis (Fig. 3.15) or a double curvature: thoracic convex to the right and lumbar convex to the left. In girls between 6 and 10 years of age the curvatures are more severe than in boys. If there is a convex thoracic curve to the left at this age, intraspinal pathology should be ruled out with an MRI. This also applies to curvatures of more than 20° because in 25 % of such cases other spinal pathology will be found. The curvatures never disappear spontaneously as is the case in infantile idiopathic scolosis. About 90 % of juvenile lateral curvatures, are progressive and require treatment especially after 10 years of age (Table 3.1). If the rib-vertebral angle difference (RVAD) is less than 10°, there is generally no progression in the curvature. Progressive curvatures are mostly those with a rib-vertebral angle difference (RVAD) greater than 10°. This is particular so in the case of curvatures with an apex of the curvature between T8 and T10. This is also the case when the angle is more than 45° at the first consultation with a thoracic kyphosis of less than 20° (normal range 20–50°). Juvenile idiopathic scoliosis must be checked radiologically every 4 months to see if there is any progression.

Scoliosis in adolescence is the most common type. In the age group between 10 and 15 years, 2 % have a lateral curvature between 10° and 20°, with a male:female ratio of 1:2. A curvature between 20° and 30° occurs in 0.3–0.5 % in this age group, with a male:female ratio of 1:5. A curvature of more than 30° occurs in 0.1–0.3 % of adolescents, with a male:female ratio of 1:10. The most common curvature is a right convex thoracic curvature (Fig. 3.16), followed by a double curvature thoracic to the right and lumbar to the left and in the third place a curvature with a left or right convex lumbar scoliosis. If there is a left convex thoracic curvature at this age, intraspinal pathology must be ruled out with an MRI. The first complaint is not always the lateral curvature of the spinal column but an elevated position of the shoulder with a crease on the concave side of the body or that one breast is positioned slightly more anteriorly than the other. Asymmetry of the air silhouettes between arms and trunk is often noticeable. The lateral curve may not be progressive. In some cases it is stationary. As a rule of thumb, the following applies: the greater the curvature at the moment it is identified, the greater the chances are of progression, especially in children between the ages of 10 and 12 (Table 3.3). On average, one can say that in children between the ages of 10 and 15, with curvatures less than 20° the chances of progression are 20 %, and in curvatures more than 20° the chances of progression are 70 %. It is impossible to predict which curvatures will remain stationary and which won’t, although thoracic curvatures have greater chances of progression than lumbar ones. Curvatures less than 30° increase little during the rest of their lives after the children have grown up. A curvature between 30 and 50° increases 10–15 % after growth. However, if the scoliosis is more than 50° the lateral curvature increases due to premature degenerative changes in the intervertebral joints and the intervertebral discs. At the thoracic level this increase can even amount to 30° at an older age, with an average increase of 1° per year. In lumbar curvatures there is less of an increase, but at this level more pain is experienced with these curvatures than with thoracic curvatures. In curvatures less than 50° the chances of back problems is not greater than in individuals without a scoliosis. Cardiopulmonary problems only occur with curvatures more than 60–70°. A reduced life expectancy is only the case with curvatures of 100° or more.

Scolioses with a lateral curve between 10° and 20° are checked once every 4 months by an experienced practitioner to assess possible progression in the lateral curve. If these check-ups show that the curvature is increasing, or if the practitioner has doubts about it, new X-rays must be taken.

In the case of progression a plaster cast or orthosis treatment is indicated. In the case of progression one should delay carrying out a spondylodesis if possible until after 10 years of age.

This is usually progressive, especially after 10 years of age. The first step is to treat with a orthosis. The majority of these scolioses can undergo a spondylodesis after the age of 10.

Progression in an adolescent idiopathic scoliosis usually occurs in early puberty, when armpit and pubic hair become manifest and external sexual characteristics develop, such as growth of the breasts and the testicles. In a progression of more than 5° a orthosis will be prescribed. The orthosis should be worn day and night, preferably for 23 h a day. The scoliosis and the orthosis are checked every 4 months. This treatment is continued until growth is complete. In girls growth stops at around the age of 14, in boys around the age of 16½. One gets and impression when growth is completed by measuring body height at each checkup. If the body height remains constant on two consecutive checkups, in girls aged 12½ or older and in boys aged 14½ or older, a skeletal image of the left hand can be made to see if growth has really stopped (Fig. 3.19).