3.13 Syndromal scoliosis

Some syndromes have a high incidence of scoliosis. This occurs due to poor neuromuscular control, deficient soft tissue restraints, or dystrophic bone. The intrinsic strength of the spinal column is reduced and deformities have a higher prevalence rate, present earlier in life, and tend to have more serious progression potential.

It is important in syndromal spinal deformities to understand the patient’s needs in a holistic way, and thus the spinal problems should not be divorced from the other, often much greater, needs of the child.

Although the development of all the conductive airways is complete at birth, only a relatively small number of respiratory bronchioles and alveoli exist. These multiply many times from the numbers present at birth to their full maturation by the age of 7 years. Restriction of the available space in the thoracic cavity can have a major effect on lung development. After birth until about the age of 7 years the effect is on the number of alveoli rather than the number of airways. Early-onset scoliosis under the age of 7 years, particularly in the first year or two of life, can result in serious future health problems.

The great majority of infantile idiopathic scoliosis cases are benign and resolve without treatment. Twenty-five per cent do not resolve naturally; in most of these progression can be prevented by treatment or they can be made to resolve eventually. In 5% of infantile idiopathic cases the natural history is severe progression (Figure 3.13.1).

Parameters such as the size of the curve (Cobb angle) and the degree of transverse plane deformity (rib vertebra angle difference (RVAD)) are important criteria in distinguishing possibly progressive from possibly resolving deformities; clinical parameters are far more important. The overall child assessment is more important to assessing potential curve progression. The healthy well child with no significant comorbidities is likely to represent a fetal moulding that normally resolves when tone is fully developed. The neurologically challenged child with associated comorbidities is more likely to progress than the idiopathic scoliosis patient.

In addition to the geometric parameters measurable on a frontal spine film (Figure 3.13.2) (i.e. Cobb angle in excess of 30 degrees and RVAD in excess of 20 degrees), clinical assessment of curve stiffness is also important. The resolving curve tends to be flexible, but the progressive curve, particularly the malignant one, tends to be rigid. Resolving curves readily overcorrect, but progressive curves hardly change at all.

Males are affected more than females in a ratio of 3:2. Thoracic curves are more common, but other patterns are not unusual. Most thoracic curves are convex to the left. Right thoracic curves in females and double-structural curves seem to have greater progression potential.

The condition is thought to be due initially to moulding of the malleable infantile skeleton. This is supported by the fact that plagiocephaly, plagiothorax, palgiopelvy, bat ear, and tight sternomastoid are all correlated with the convex side of the scoliosis. There is a higher incidence of mental retardation, congenital hip dislocation, congenital heart disease, and inguinal hernias, and there is a definite familial trend. These additional clinical features strongly support the notion that early-onset progressive scoliosis is syndromal rather than idiopathic. This is confirmed by the association with chromosomal abnormalities.

If the child is diagnosed and referred within the first year of life, conservative treatment can be effective at promoting resolution or preventing progression. The older the presentation, the more difficult it is to achieve these goals. Once the child reaches the age of 4 or 5 years, non-operative treatment is probably of no avail. Serial elongation–derotation–flexion (EDF) casts are applied under a light general anaesthetic every 2 or 3 months, with the precise frequency being determined by growth, hygiene, and the state of the cast. As the plaster hardens, pressure moulding of the spine is carried out to exert an untwisting effect. Windows are then cut in the back and front of the cast to allow vests to be changed whenever required and thus promote hygiene. Once the child has reached the age of 4 or 5 years, the deformity becomes too rigid to be influenced by external cast pressure. The child is then observed at intervals of 6 months. Curves can resolve over several more years, with the rotational component being the last part to disappear. Curves that have been prevented from progressing should clearly be observed regularly throughout the adolescent growth period. There is no evidence that bracing favourably influences the natural history of any form of scoliosis, least of all the early-onset type.

Surgery is indicated for cases that have resisted serial cast treatment. It can potentially do more harm than good. As with all structural scolioses, the problem is one of relative anterior spinal overgrowth and therefore a posterior fusion is contraindicated as it will create a tether that may lead to a crankshaft deformity and a worse outcome.

An anterior epiphysiodesis to prevent the anterior growth is essential to prevent further curse progression. The treatment options are then to continue with external splintage or use a posterior growth system (Figure 3.13.3). Posterior growth systems just distract the spine and they require reoperation and lengthening every 6 months in order to gain maximal spinal length. Alternatively the Luque trolley technique implants rods that distract over wires as the spine grows. The disadvantage of the trolley systems is that the spine is opened at all levels whereas the growing rods can be passed submuscularly. Premature growth arrest is possible if the whole spine is opened by a growing pseudarthrosis controlled by the rods occurs in the majority and prevents patients have as many surgeries as with a growth rod. Which ever system is used they have a high complication and reoperation rate requiring intense follow-up and management.

Thoracic insufficiency syndrome (TIS) is used to describe the inability of the thorax to satisfactorily support lung growth, respiratory function, or spine development due to congenital and acquired chest wall, spine, and other syndromic deformities. This is associated with Jeune syndrome (asphyxiating thoracic dysplasia) or Jarcho–Levin syndrome (multiple vertebral and rib fusion anomalies. Traditional spinal arthrodesis will only worsen the pulmonary compromise associated with these conditions and will not correct the thoracic deformity. The titanium rib project developed by Campbell and Smith is an expandable device attached to the ribs and spine. This device is associated with an opening thoracic osteotomy. This device is lengthened 6-monthly until skeletal maturity. These surgeries have allowed thoracic wall expansion to improve lung development.

There are two main sub-divisions, peripheral neurofibromatosis (NF-1) and central neurofibromatosis (NF-2). Spinal deformities are associated with NF-1 which is the common form of neurofibromatosis, with a prevalence rate of six per 1000. It has an autosomal dominant mode of inheritance with high penetrance but variable expressivity. There is a high mutation rate with many sporadic cases presenting as new mutations. The condition can affect all components of the musculoskeletal system, but the common clinical findings, are: nerve sheath tumours; café-au-lait spots; diffuse, soft tissue hypertrophy; subcutaneous nodules; bone hypertrophy; vascular malformation; congenital tibial pseudarthrosis; congenital shortening; osseous cysts; melorheostosis; and neuroendocrine tumours. Any two of the following are considered diagnostic:

Those individuals who are minimally affected clinically have deformity patterns which are indistinguishable from their idiopathic counterparts. Patients present with late-onset idiopathic-type scolioses or with late-onset idiopathic-type hyperkyphosis (Scheuermann’s disease). Only careful clinical assessment of these criteria satisfies the diagnosis. These deformities can be managed in the same way as idiopathic deformities. Hyperkyphosis can be successfully treated orthotically.

The scoliosis affecting NF-1 patients is no different from idiopathic scoliosis itself; it is equally resistant to orthotic treatment. Only surgical treatment alters its natural history and the decision to treat is based on the same principles as idiopathic scoliosis. Preoperative magnetic resonance imaging (MRI) scanning is mandatory in order to detect any intracanal abnormalities which could produce neurological problems during surgery.

With NF-1 patients there is a tendency for deformities to reach unacceptable appearance earlier than with ordinary idiopathic scoliosis. The deformity is then at a higher risk of a crankshaft phenomenon if the deformity is only approached from posteriorly. Therefore it is appropriate to carry out an anterior discectomy and growth plate excision before posterior stabilization, in order to prevent late curve deterioration.

In severe NF-1 cases dystrophic bone changes may occur. In the axial skeleton, these include rib pencilling, enlarged intervertebral foraminae, and scalloped vertebral surfaces (Figure 3.13.4). The spinal deformities in severely expressed NF-1 are different. The curves tend to be short, sharp, and angular with a lot of rotation, while the kyphoses are also angular and tend to be in the thoracic or even cervical regions. The two often go together, with a lower thoracic lordoscoliosis and a high thoracic kyphosis above. These dystrophic types of deformity tend to develop at a much younger age and have much more progression potential. The degree of disfigurement produced by a deformity of considerable magnitude, often in association with short stature and other surface deformities, does provide indications for early surgical treatment. Because rapid progression of the dystrophic lordoscoliosis is inevitable, there is no sense in withholding surgical treatment. However, combined posterior and anterior surgery is essential, with the focus of attention on the front of the spine. Multiple discectomy with growth-plate ablation is a mandatory first stage (Figure 3.13.5). Definitive posterior instrumentation and fusion should be carried out in the older child, and some form of growing instrumentation should be provided for younger patients.

Represents a group of disorders which arise from primary inherited defects in collagen synthesis with the common feature of bone fragility. The most common biochemical abnormality is defective synthesis of sufficient type I collagen. The diagnosis is usually made on the basis of the presence of blue sclerae or a positive family history. Floppy mitral valves and aortic incompetence are important complications. The disease may be sufficiently mild to resemble those changes seen in idiopathic juvenile osteoporosis.

In severe osteogenesis imperfecta, repeated fracturing occurs which may start in utero, thus producing gross deformity and considerable ambulatory disability. Death is not uncommon either at birth owing to the soft deficient skull or in the first 2 years of life as a result of respiratory infection. Blue sclerae and deafness are less common in severe disease.

Lateral spinal radiographic appearances show multiple compression fractures and biconcave vertebrae. Spinal deformities are rare in mild disease, with a prevalence rate no greater than in idiopathic scoliosis, but patients with severe disease invariably have a spinal deformity (Figure 3.13.6). These are of the two primary types—lordoscoliosis and kyphosis. Bracing can be of some benefit in kyphotic situations, although soft ribs can easily be deformed by the brace. Progressive deformity is difficult to manage because of the soft bone. Some form of segmental instrumentation is required to dissipate loads along with a profuse amount of allograft bank bone to facilitate a solid fusion.

A dominantly inherited disorder characterized by skeletal deformity, arachnodactyly, dislocated lenses, and aortic dilatation. Fibroblast-produced collagen is deficient and the soft tissue laxity thereby produced leads to joint hypermobility or dislocation, a tendency to hernias, aortic dilatation, and spinal deformity by increasing the intrinsic load on the spine consequent upon deficient soft tissue support.

Affected individuals are tall and thin, and the increase in stature is disproportionate. The fingers and toes are long and thin, and the palate is high and arched. Aortic incompetence, dissecting aneurysm, and mitral and tricuspid valve disease are the usual causes of death. The correct diagnosis is of extreme importance because many tall slim marfanoid patients present in scoliosis clinics and cardiology review is required after.

The prevalence rate of scoliosis in Marfan’s syndrome is about 50% and the nature of the deformity is very similar to idiopathic scoliosis. The prevalence rate of kyphosis seems to be very small. Double-structural curves are more common in Marfan’s syndrome. Treatment is along the same lines as that recommended for idiopathic scoliosis; for larger curves or earlier onset preliminary anterior discectomy should precede posterior segmental instrumentation and fusion (Figure 3.13.7).

The condition resembles Marfan’s syndrome but can be differentiated by the presence of widened epiphyses and metaphyses, frequent osteoporosis of the spine, and in particular an increased incidence of thromboembolism. It is due to a deficiency of the enzyme cystathionine synthase. Homocystinuria patients generally have some degree of mental retardation, a malar flush, fair hair, dental crowding, large skull sinuses, and a narrow high-arched palate. The most serious problem is a strong tendency to thrombosis of both arterial and venous systems; in one series, two out of five serious thromboses followed relatively unimportant elective orthopaedic procedures.

There is platyspondyly on lateral spine radiographs and a 50% incidence of scoliosis on frontal radiographs, which appears to be similar to idiopathic scoliosis.

This is an autosomal dominant condition characterized by contractures which are present at birth and tend to affect the proximal interphalangeal joints of the fingers, the elbows, the knees, and the ankles. Spontaneous improvement in these contractures always occurs. In addition, there is dolichostenomelia (long thin limbs), arachnodactyly, and abnormalities of the external ears. Scoliosis can occur; it is similar to idiopathic scoliosis and should be treated similarly.

Excessively stretchable, fragile, and bruisable skin is also associated with loose-jointedness. A number of different types of Ehlers–Danlos syndrome have been described; in some there is excessive bruising and bleeding after minor trauma, and in others there is uncontrollable haemorrhage and even spontaneous bowel rupture. Type 6 is the occular-scoliotic form due to a deficiency of lysyl hydroxylase and is associated with floppy joint hyperextensibility, vascular abnormalities, and an easily ruptured eye globe. Severe scoliosis has been described in several series, but inspection of the data suggests that these are, in fact, fairly mild curves, rather like late-onset idiopathic scoliosis.

These disorders affect the skeleton through failure of normal breakdown of complex carbohydrates which accumulate in the tissues and appear in excess in the urine. As a result many different tissues can be affected, including cartilage, bone, liver, and central nervous system. There are several different types of mucopolysaccharidosis (MPS) but only three are particularly associated with spine problems.

MPS 1H (Hurler’s syndrome) produces severe mental and skeletal changes, and death usually occurs by the age of 10 years. The typical facial appearances of prominent eyes, frontal bossing, and coarse features with a flattened nasal bridge gave rise to the original description of gargoylism. There is abdominal enlargement due to hepatosplenomegaly. The fingers are stubby, the hands are broad, and the joints are stiff. There is an oblique acetabulum with subluxating hips. Death occurs from respiratory infection or coronary heart disease due to the accumulation of mucopolysaccharides. The spine is affected by a persistent infantile biconvex vertebral body shape and characteristic vertebral beaking due to failure of the anterosuperior corners of the vertebrae to form, making them hook-shaped. There is a characteristic kyphosis and the attached ribs are paddle shaped.

MPS II (Hunter’s syndrome) is less common and milder than Hurler’s syndrome, and affected individuals survive into the third decade. Only males are affected. Again, there is short stature with stubby fingers, stiffness, and contracture. The spinal changes are similar to Hurler’s syndrome but less obvious.

MPS IV (Morquio’s syndrome). There is normal intelligence and variable physical disability, but the major problems are a short-trunked stature with a height of not more than 120cm. There is joint and skin laxity, genu valgum, and corneal clouding. The pelvis is hypoplastic and there is epiphyseal dysplasia. Death tends to occur as a result of either cardiorespiratory failure or spinal cord compression. As with MPS I and MPS II, there is a thoracolumbar kyphosis with platyspondyly and anterior vertebral breaking but there are two additional major spinal problems in Morquio’s syndrome: a thoracolumbar kyphosis (Figure 3.13.8) and atlantoaxial instability as a result of a deficient odontoid. The thoracolumbar kyphosis is associated with a barrel-shaped chest and prominent sternum to the point where premature fusion of the sternal segments with an immobile chest can lead to severe respiratory dysfunction.

If the kyphosis is not severe it can be braced, but if neurological symptoms develop then it must be treated by anterior dural decompression, strut grafting, and posterior metalwork neutralization as with any kyphosis producing cord compression.

C1–2 instability is common and, while there may be clear physical evidence of myelopathy, the neurological signs are often atypical with tiredness, weakness, vague leg pains, paroxysmal tachypnoea, respiratory arrest, syncope, and gait abnormality. Although some of these signs can be bilateral, they are often expressed unilaterally.

The notoriety of C1–2 instability is such that C1–2 fusion should be carried out prophylactically in all cases, and this implies surgery before the age of 10 years.

These are a group of conditions with the common factor that there is disordered development and growth of some part of the skeleton. There are many of these and, as they are not frequently encountered. The Skeletal Dysplasia Society provides guides on the diagnosis and prognosis for these rare conditions and should be consulted when the diagnosis is considered.

Multiple epiphyseal dysplasia is characterized by short stature with significant involvement of the epiphyses of hips and knees. The hands are characteristically short with stubby fingers. The problem here is of irregular epiphyseal growth without normal endochondral ossification while bone modelling is normal. The femoral capital epiphysis is always involved in a severe Perthes disease-like process. Secondary osteoarthritis is common in early adult life. The spine can be involved in a process similar to Scheuermann’s disease and responds to extension bracing. Significant scoliosis is not encountered.

Chondrodysplasia punctata (stippled epiphysis) is characterized by stippled epiphyses, extra-epiphyseal calcification, skin lesions, cataracts, mental retardation, short limbs, and short stature. The spinal stippling is caused by chalky deposits, and there are separate ossification centres for the body and posterior elements giving a characteristic separated appearance on a lateral radiograph (Figure 3.13.9). Spinal deformities, if present, are of the congenital variety with a recognizable anomaly at the curve apex.

Achondroplasia is a bone dysplasia with predominantly metaphyseal involvement and is an autosomal dominant condition with the great majority appearing as new mutations. The typical appearance is that of short limbs with short fingers on trident hands, a bulging cranium with a low nasal bridge, and characteristic pelvic changes with squaring of the iliac wings, more horizontal acetabulae, and widening of the upper femoral metaphysis with a short femoral neck.

There are two important effects on the spine in achondroplasia—spinal stenosis and a thoracolumbar kyphosis. Both can give rise to neurological problems. As with other dysplasias and the mucopolysaccharidoses, kyphosis is particularly prevalent and is due to a thoracolumbar anterior wedged bullet-shaped vertebra. This produces a local angular kyphosis (Figure 3.13.10) but, importantly, 90% of these kyphoses resolve spontaneously. Therefore the spine should be observed to allow the natural history to reveal itself. If the kyphosis persists and progresses to the point of neurological disability, anterior dural decompression and strut graft posterior metalwork is necessary.

The most common sites for a stenosis in the achondroplastic subject are the thoracolumbar or upper lumbar regions. The anteroposterior diameter of the spinal canal is particularly reduced. Less than half of achondroplastic individuals have symptoms or signs of spinal stenosis, and less than 20% exhibit objective neurological findings. Preoperative imaging determines the levels that require being decompressed. In the achondroplastic adult, adequate decompression can be carried out by undercutting so as not to jeopardize posterior facet joint stability bilaterally. In the immature spine even this degree of decompression can give rise to a progressive kyphosis and thus concomitant fusion is necessary (Figure 3.13.11). Sometimes preoperative imaging demonstrates a prolapsed intervertebral disk rather than bony canal stenosis as the offending problem.

The upper cervical spine can also be the source of neurological problems because the occipitalization of C1 in association with stenosis of the foramen magnum can give rise to secondary atlantoaxial instability. Fusion from C2 to the occiput in extension is required.

Spondyloepiphyseal dysplasia tarda is associated with mild dysplasia of vertebrae and large joints, with the hips and shoulders particularly affected. It is often confused with Morquio’s syndrome. There is a small pelvis, a deep acetabulum, and a short femoral neck, but the distal epiphyses are not involved. The trunk is short with sternal protrusion and the vertebral changes are typical. There is platyspondyly, but the vertebral bodies are humped posteriorly, differentiating them from multiple epiphyseal dysplasia and MPS IV. Significant kyphosis is not the rule but may have to be dealt with by anterior decompression, strut grafting, and posterior metalwork. Mild kyphoses can benefit from extension bracing.

Spondyloepiphyseal dysplasia congenita is rare. The features of platyspondyly, Scheuermann-type changes of kyphosis, and bullet-shaped thoracolumbar vertebrae are more pronounced than in the tarda variety but can respond to extension bracing.

Diastrophic dysplasia is an autosomal recessive condition of short limbs, club-foot, joint contractures, and spinal deformity. A cystic swelling of the ear in the first few days of life later ossifies to produce the typical ‘cauliflower ear’ deformity. The first metacarpal is short, giving rise to the term ‘hitch-hiker’s thumb’. There are dysplastic epiphyses and the hips are particularly severely involved. The club-foot deformity, like early-onset progressive malignant scoliosis, is particularly resistant to correction. Height seldom exceeds 1m.

There are a number of important spinal problems in diastrophic dysplasia. Odontoid hypoplasia can give rise to atlantoaxial stability which may require fusion. The cervical spine is particularly prone to the development of a kyphosis which can in its own right produce neurological problems and even death. Sometimes the kyphosis can improve spontaneously, and therefore the neurological situation should be closely monitored before prescribing anterior and posterior fusion. Scoliosis is common in dystrophic dysplasia but curvature seldom becomes severe. Because of the relatively young age of patients, anterior and posterior fusion is required. Spina bifida occulta is a virtually constant finding in either the neck or lumbar region, and if instrumentation is to be used then the tethering effect must be preoperatively excluded by MRI scanning prior to the application of metalwork.