Idiopathic scoliosis: biomechanics and biology

For whatever reason, right-left asymmetry has attracted an illogical proportion of research effort. Non-structural scoliosis, for example secondary to a leg length inequality, is indeed a problem of right-left asymmetry, but structural scoliosis is a complex three-dimensional deformity involving all planes. Biomechanical, biological and clinical evidence indicates clearly that the problem is one of front-back asymmetry and not right-left. The importanc of biological factors lies in their ability to bring the spinal column to and beyond its buckling threshold. Thus a taller and more slender spine is more liable to bend and, being stiffer in the sagittal plane, favours movement into other planes. This epitomises the spine of the scoliosis patient who is growing faster with a spinal template similar to other family members allowing idiopathic scoliosis to express itself genetically. It is the opposite condition to idiopathic hyperkyphosis (Scheuermann's disease), but this deformity is rotationally stable, thus remaining in the sagittal plane. The presence of an adjacent area of lordo-scoliosis below the region of hyperkyphosis testifies to the common nature of the pathogenesis of idiopathic scoliosis and Scheuermann's disease. It is the area of compensatory hyperlordosis below the Scheuermann's area that has obligatorily buckled and represents a human model supporting the lordosis theory, as does surgically tethering the back of the young growing human spine, which crankshafts accelerated progression. Similarly the only successful animal model of the formation of idopathic follows creation of a lordotic spinal segment in an otherwise kyphotic spine. For centuries, engineers have recognised that the mechanical behaviour of a column under load is influenced by geometry, as well as by material properties; it is clear that the spinal column also obeys these well-described laws.     

Idiopathic scoliosis: characteristics and epidemiology

An epidemiological survey of idiopathic scoliosis derived by school screening in Greece has shown a three-fold rise in prevalence rate from 1% in 6-year-olds to more than 3% in 15-year-olds. Moderate curves (with a Cobb angle of 10 degrees to 19 degrees) are the most common curve magnitude encountered in both boys and girls. Typical curves (right thoracic, left lumbar, or right thoracic left lumbar double structural configurations) become relatively more prevalent with rising curve magnitude, while atypical curve patterns (left thoracic, right lumbar, or left thoracic right lumbar double structural configurations) reciprocally diminish. Growth is clearly an important environment in which curves progress and peak prevalence rates occur at the ages of 11 years and 13 years. Although it is not possible to prognosticate about the individual case, attention to these characteristics derived from epidemiological surveys is useful in assessing future curve behavior.     

脊柱侧凸的临床病因学分类研究

目的 探讨脊柱侧凸病因学构成的变化与发展情况。方法 对６２１例脊柱侧凸患者,以及其中的３９１例９～２８岁常见手术年龄组患者分别进行病因学分类,并对两者的病因学构成百分比进行比较。结果 非特发性脊柱侧凸病例占总病例数的２５．３％（１５７／６２１）,占９～２８岁年龄组脊柱侧凸病例的３４．０％（１３３／３９１）,其中先天性脊柱侧凸并发脊髓发育性畸形高达３８．６％。结论 脊柱侧凸可由多种原因引起,随着临床     

Idiopathic scoliosis: foundation for physiological treatment

The three-dimensional nature of the idiopathic spinal deformity has been investigated in cadaveric specimens and patients with both idiopathic scoliosis and idiopathic kyphosis (Scheuermann's disease). In both scoliotic and kyphotic deformities the essential lesion lies in the sagittal plane with apical vertebral wedging. In idiopathic scoliosis there is an apical lordosis which being biomechanically unstable rotates to the side to produce a scoliotic deformity as a secondary component. In contradistinction the kyphotic wedging process of Scheuermann's disease is mechanically stable and any associated idiopathic type scoliosis occurs above and below the region of kyphosis. When an asymmetric lordosis is created in the growing New Zealand white rabbit, a progressive lordoscoliosis is readily produced and when the thoracic kyphosis is restored the scoliotic deformity shows evidence of regression and this forms the basis of physiological treatment. In 25 patients with idiopathic thoracic scoliosis the thoracic kyphosis has been restored and this leads to enhanced correction of the deformity in all three planes.     

Idiopathic scoliosis and growth--a biomechanical consideration

Growth force proposed as an etiological factor in idiopathic scoliosis was analysed by a mathematical simulation; the results were compared with clinical roentgenograms of patients with idiopathic scoliosis. Growth force is a self-equilibrating internal stress derived from unbalanced growth between two adjacent structures with different growth rates. In the simulation, the localized growth force made the whole spinal column buckle. Two hundred anteroposterior roentgenograms were then compared with the buckling curves. The three most similar buckling curves for each roentgenogram were selected. Of the 600 selected curves, 406 were considered to have produced a high similarity. The curves produced by a growth force extending over a small area, especially at the mid-lower thoracic and lumbar regions, were qualified as curves with a high similarity. The growth force thus does not appear uniformly all over the spinal column but locally and at the mid-lower thoracic or lumbar region. This growth force may represent a factor in the etiology of idiopathic scoliosis.     

Idiopathic and congenital scoliosis in twins

This report contains a case presentation of monozygotic twins who had concordant right thoracic scoliosis of differing severities. One twin also had an associated congenital left lumbar scoliosis and urologic abnormalities. This report would suggest that the genetic basis of scoliosis may occur at multiple gene loci.     

Idiopathic scoliosis. Natural history

This study reviews the prognostic factors in curve progression in untreated idiopathic scoliosis patients followed an average of 40 years. A select group of 54 patients with 67 curves with complete radiographs from initial presentation, skeletal maturity, 30-year follow-up and 40-year follow-up were analyzed for radiographic factors leading to curve progression. Analysis of these patients confirmed that the radiographic factors identified at skeletal maturity leading to curve progression apply to the skeletally immature patient as well.     

Clinical etiological classification of scoliosis: report of 1289 cases

Objective: With the development of diagnostic techniques and in‐depth understanding of lateral curvature of the spine (scoliosis), it is possible to differentiate idiopathic scoliosis from other forms with various known etiologies. The present study was to analyze data collected at the authors' center according to the current etiological spectrum and classification of scoliosis. Methods: One thousand, two hundred and eighty‐nine consecutive patients with different forms of structural scoliosis were reviewed. The average age at first visit was 18 years, ranging from 4 months to 79 years. Corrective surgery was performed on patients aged from 9 to 28 years; their clinical data were retrieved for independent statistical analyses, and further compared with those obtained from the whole group. Results: The prevalence of non‐idiopathic scoliosis was 25.3% in the whole series, but it increased to 34% in the surgical group aged from 9 to 28 years. Thirty‐nine percent of patients with congenital scoliosis presented at least one developmental spinal cord malformation. Conclusion: The current study has shown that the etiological distribution of scoliosis has changed a lot from what was true decades ago. Developmental malformation related to scoliosis is one of the risk factors for neurological complications during corrective surgery, so it is important to make an accurate diagnosis and take appropriate prophylactic measures to avoid relative neurological complications.     

Idiopathic scoliosis in families of children with congenital scoliosis

Although most cases of congenital scoliosis are thought to be of sporadic etiology, it is not known whether other types of spinal deformity occur in families of individuals with this type of scoliosis. Children with congenital scoliosis were identified through a review of health records and radiographic report databases. Of 237 children with congenital scoliosis investigated, 49 (20.7%) reported a family history of spinal deformity. Detailed pedigrees were done, which showed a history of idiopathic scoliosis in 17.3% of the 237 families. This is a higher than expected rate of spinal deformity in families of children with congenital scoliosis, and the strong association of idiopathic scoliosis in families of children with congenital scoliosis has not been reported previously. Although this finding could be related to the chance occurrence of multiple genetic abnormalities or sporadic events in these families, it does raise the possibility that one genetic defect at least predisposes these families to having different types of spinal deformity develop.     

Idiopathic scoliosis: prognostic value of the profile

Summary A study was undertaken to establish the significance of the sagittal shape of the spine in 138 consecutively treated girls with early idiopathic thoracic scoliosis. All were treated in a Boston brace. Two groups were formed: group I consisted of 120 girls whose scoliosis remained stable in the brace, group II of 18 girls who required a spinal fusion for progressive curves despite the brace. For each spine, the orientation of each vertebra to the horizontal in the sagittal plane was measured on the earliest lateral radiogram, taken when the anterior curve still had a Cobb angle of less than 20°. A significant difference in spinal profile was found between the two groups. Progressive curves showed a more retroverted orientation of mid- and high thoracic vertebrae than stable curves.     

Idiopathic scoliosis in adolescence. Incidence and progression of untreated scoliosis

Decision making in adolescent idiopathic scoliosis (AIS) requires a thorough knowledge of the natural history. Treatment decisions must be individualized based on the probabilities of progression. Any treatment for AIS must influence the "natural history" in a positive way. The natural history of AIS with reference to back pain, effects on pulmonary function, psychosocial effects, mortality, effect on pregnancy and risks of progression in the immature and mature patient are presented.     

Idiopathic scoliosis: long-term follow-up and prognosis in untreated patients

Two hundred and nineteen patients with untreated adolescent idiopathic scoliosis who were seen at the University of Iowa between 1932 and 1948 were studied, and recent information was available on 194 of the patients. The mortality rate was 15 per cent. Backache was somewhat more common in these patients than in the general population, although it was never disabling. The backache was unrelated to the presence of osteoarthritic changes on roentgenograms. Many curves continued to progress slightly in adult life, particularly thoracic curves that had reached between 50 and 80 degrees at skeletal maturity. The lumbar components of combined curves between 50 and 74 degrees also tended to progress. Pulmonary function was affected only in patients with thoracic curves.