Adolescent idiopathic scoliosis: metric analysis of the deformity.

In order to explore the concept that scoliosis is fundamentally a loss of left-right symmetry. surface topography was used to measure asymmetry in three dimensions at three levels on the back surface. Statistical analysis of prospectively collected topographic, radiographic and clinical data, in girls with adolescent idiopathic scoliosis, was carried out and comparisons were made with theoretically perfect symmetry (test value of zero). All scoliosis showed statistically significant differences in coronal dimensions, index points on the convex side of the scoliosis being further from the mid-line than those on the concave side. Primary thoracic scoliosis differed from thoracolumbar and lumbar in that they showed directional asymmetry at all levels and in all directions, the side of the scoliosis convexity being broader, taller and thicker. This asymmetry is not due to posture, spinal balance or trunk rotation, as left and right sides are being compared independently of their orientation in space. The asymmetry is of size in three dimensions and size is determined by growth. Growth is a three dimensional process, but does not necessarily occur equally in all three. Differential growth is both directional and regional, particularly during the pubertal growth spurt, when proportions change substantially, and is controlled by many genes, as well as by hormones and signalling molecules. The implication is that scoliotic deformity is the result of asymmetric growth, not confined to the vertebrae, but affecting the entire trunk. This is a developmental, rather than pathological, phenomenon. It makes questions of aetiology redundant and natural history logical.

Handedness and spinal deformity.

Biological lateralisation is clearly manifest in scoliosis, yet its relevance is unclear. Goldberg et al. (Spine. 15(2):61-64. 1990) found an association between curve pattern and hand-preference in a screened population, but no increase in sinistrality. Milenkovic et al, (European Journal of Epidemiology, 19:969-972,2004) concluded left-handedness was a risk factor in a screened group. The database was reassessed to determine whether clinically significant scoliosis was associated with sinistrality or differed from the population norm of 10%. Patients attending the scoliosis clinic were asked their preferred writing hand. 1,636 patients were identified with complete data. Overall, left handedness occurred in 11.5%, greater than the general population (p=0.04) Left hand preference was found to be increased in boys with infantile idiopathic scoliosis and in girls with infantile, juvenile, congenital and syndromic scoliosis, but was reduced in girls with adolescent idiopathic scoliosis. Scoliosis lateralisation was random in infantile and congenital scoliosis, while left curve patterns were decreased in girls with juvenile idiopathic scoliosis and increased in boys with syndromic scoliosis. Curve pattern and handedness correlated in asymmetry in boys and girls and in girls with radiologically confirmed adolescent idiopathic scoliosis, but not in any other type. This study cannot confirm findings of left-handedness as a risk factor for spinal deformity. Its incidence is reduced in girls with adolescent idiopathic scoliosis, and the increased sinistrality in infantile scoliosis is not a new finding (Rauterberg & Tonnis Ger. Z.Orthop. 109(14):676-689. 1971). Lateralisation is undoubtedly a factor in scoliosis, but does not have a simple causal relationship, probably deriving from the underlying scoliotic process, rather than contributing to it.

Surface topography and vectors: a new measure for the three dimensional quantification of scoliotic deformity.

The monitoring of spinal deformity uses many techniques: clinical history and physical examination for patient status, radiography for precise spinal delineation and Cobb angle, topography to quantify cosmesis and to approximate the Cobb angle. Experience with a system based on Raster photography has shown that adequate correlation with the Cobb angle is achieved, but that the relationship between spinal curvature and cosmetic effect is not simple. A measure was developed to quantify the asymmetry of the back, making it available to statistical analysis, without expressing it in terms of the Cobb angle or referring to trunk balance or rotation. The calculation expresses symmetry about the median saggittal plane (first thoracic vertebra to natal cleft), reflecting the right half onto the left and measuring the three-dimensional displacement between corresponding fixed points on the trunk. Tolerance limits were calculated and correlation with Cobb angles using routine scans was analysed. There were statistically significant correlations between the Cobb angle and all vectors except the middle antero-posterior. All vectors correlated with each other, except again for the middle Z or anteroposterior which correlated only with the middle and lowermost sets. Applied to natural history and to surgical outcome, this new parameter provides a different quantification of back shape which can be used both for patient assessment and monitoring, for the evaluation of the cosmetic (as opposed to the radiological) effect of treatment, and for aetiology and natural history studies.

Respiratory function and cosmesis at maturity in infantile-onset scoliosis.

STUDY DESIGN: Retrospective review of patient records, clinical and radiographic, and patient recall for full pulmonary function studies and surface topography. OBJECTIVES: Assessment of outcome of treatment policy after age 15 during the previous 30 years to establish the efficacy of management protocols in a group that is too small and too varied for more formal assessment. BACKGROUND DATA: Spinal deformity presenting during infancy or early childhood poses a clinical problem caused by small numbers, long growth period, variable presentation and treatment methods, and, finally, the length of time that must pass before meaningful outcome results can be assessed. The aims of treatment are to preserve respiratory function and cosmetic appearance. MATERIALS AND METHODS: The records of patients with infantile onset, nonsyndromic, and noncongenital scoliosis were reviewed. Thirty two were at least age 15 years at the time of review and 21 of these agreed to attend for full pulmonary function testing (spirometry, lung volumes, gas diffusion) and surface topography, whereas two more had recent spirometry results available in their record. Treatment had been serial casting with Risser jacket, bracing, or surgery. RESULTS: Those whose scoliosis resolved or was stabilized by nonoperative means (N = 6) at an acceptable Cobb angle had normal cosmesis and pulmonary function (mean FEV1 = 98.7%, mean FVC = 96.6%). Those who were managed by casting or bracing and underwent surgery after age 10 (N = 6, mean age at surgery 12.9 y) had variable cosmesis and acceptable pulmonary function (mean FEV1 = 79%, mean FVC = 68.3%). Those whose deformity necessitated early surgery (N = 11, mean age at surgery 4.1 y) had recurrence of deformity and diminished respiratory function (mean FEV1= 41%, range 14%-72%, mean FVC = 40.8%, range 12%-67%). CONCLUSIONS: Although these are small numbers and treatment methods have changed since the beginning of the series, the results indicate that this condition is not simple to treat and for some children still has the risk for serious deformity and respiratory compromise. There is, as yet, no evidence that early surgical intervention in this group of patients with infantile scoliosis has altered their prognosis in any meaningful way.

The natural history of early onset scoliosis.

A retrospective analysis of the natural history and treatment outcome of scoliosis, both idiopathic and syndromic, presenting before age 10 years was undertaken. The pattern was generally one of relentless progression, with little discernible benefit from orthotic treatment and surgical correction as the outcome for the majority. This result makes imperative a properly constructed study on the evolution and long-term outcome of this less common but more significant type of spinal deformity.

Growth patterns in patients with unoperated congenital vertebral anomaly.

Retrospective analysis of height and weight data recorded during routine clinic visits of children with congenital vertebral anomaly were related to decimal age and compared with national centiles. Individuals were dropped from the study at surgery. Growth followed a normal trajectory until puberty, although girls tended to be smaller than average. At puberty, they lagged behind their peers and at maturity were shorter than average. This does not appear to be a hormonal problem, and suggests a fundamental failure of growth.

The rib hump after surgery for early onset spinal deformity.

Spinal deformity presenting early in childhood has a poor prognosis, in that progression is probable and severe respiratory compromise is a real possibility. Treatment is difficult, since these patients frequently do not respond to bracing, and surgery is sometimes performed in childhood in an attempt to control relentless progression. This carries the risk of continued deformation during subsequent growth, and the surgical procedures have been adapted in an attempt to minimise this. 25 children undergoing spinal fusion for progressive and severe deformity have sequential topographic scans which show that, despite measures to control the rib hump, progression after surgery is the rule.

The relationship between minor asymmetry and early idiopathic scoliosis.

School scoliosis screening programmes have consistently produced large numbers of referrals with minimal trunk asymmetry which then must be assessed, evaluated and perhaps investigated and monitored over a period of time before it is felt safe to discharge them as 'non-progressive.' Beyond measures to reduce their number, they have received less attention than the more interesting cases requiring treatment or surgery, which they outnumber to a significant extent. Examination of the figures from a historical database shows that the patients have no greater probability of developing significant scoliosis than their 'normal' peers . So they should not be classed as scoliosis but they are still relevant to the broader picture of aetiology.

Surface topography and the several components of scoliotic deformity.

Using previously established values for the smallest detectable difference in topographic parameters, the effectiveness of the Quantec system for monitoring progress in scoliosis was investigated. It was found that, while a significant change in Cobb angle was always accompanied by a meaningful change in at least one topographic parameter, the pattern of shape change was highly individual. It is concluded that deformity in scoliosis is not determined exclusively by the spinal curve.

Adolescent idiopathic scoliosis: is the search for aetiology constrained by the orthosis?

While the aetiology of adolescent idiopathic scoliosis is unknown, it is widely believed that the deformity can be controlled by mechanical forces applied by a corset and acting, via skin and soft tissues, to exert pressure on vertebral growth-plates (Hueter-Volkmann Law). The reported efficacy of bracing in reducing the incidence of small degrees of progression reinforces this concept. The supposed mode of action conditioned the model of pathomechanism and precludes other hypotheses. Since the critical Cobb angle changes are usually less than the probable measurement error, another criterion (treatment outcome) is also relevant. At our centre, bracing for adolescent idiopathic scoliosis has not been practised for 9 years. Out of the 153 untreated, unselected patients presenting to the general scoliosis clinic in that time and who were at least 15 years old at the last review, 43 (27.6%) of them have undergone surgery. This does not differ statistically from 22.45% (229 of 1,020) braced patients reported by Lonstein and Winter in 1994. If bracing does not significantly improve prognosis, its efficacy cannot be accepted and the hypothesis of aetiology which it underpins has no greater standing than any other.

Adolescent idiopathic scoliosis: natural history and prognosis.

Retrospective review of the scoliosis database showed adolescent idiopathic scoliosis to be the most common but least significant variety of spinal deformity. Data from 112 girls diagnosed on repeat screening showed the importance of menarche as a date in the natural history. In the whole database, there were 514 aged at least 15 years at last review, 45 boys and 469 girls. Braces were prescribed for a total of 38, mostly during the early part of the period and gradually abandoned without an increase in surgical rate. Progression depended on the age and maturity of the patient as well as the initial Cobb angle. Surgery was recommended for 27% overall. A sub-group with more complete data diagnosed after bracing had been discontinued confirmed the findings.

Surface topography, Cobb angles, and cosmetic change in scoliosis.

STUDY DESIGN: Preliminary analysis of the clinical value of surface topography in a spinal deformity clinic. OBJECTIVES: The Cobb angle is the gold standard for the monitoring of scoliosis. This study was designed to determine whether surface topography would reflect Cobb angle status with sufficient reliability to permit its safe use as an alternative means of documentation in some circumstances. SUMMARY OF BACKGROUND DATA: Surface topography offers the possibility of describing spinal deformity more fully than radiographic measures alone. To be useful, it must ignore changes due to varying posture and reliably detect differences that are clinically significant, while broadening the ability to assess deformity. METHODS: Surface topography using Quantec () was obtained routinely in all patients attending a spinal deformity unit. Intrasubject variation was reduced by taking the mean for each parameter of four repositioned scans, which gives a smallest detectable change on all measures of approximately 10 U. Fifty-nine patients with two sets of radiographs and topography scans were studied to determine the ability of the different measurements to detect significant change. RESULTS: There was a significant correlation between Cobb angle and Quantec spinal angle. A significant change in Cobb angle could be identified by associated change in at least one topographic measure in a significant proportion of cases. CONCLUSIONS: It is unlikely that topography will supplant radiography for the ascertainment of Cobb angles, because the error margins of both are wide, and the two are not measuring the same aspect of the deformity. The Quantec system is useful in patient monitoring as an alternative to radiography, without diminishing the standard of care.

Adolescent idiopathic scoliosis: the effect of brace treatment on the incidence of surgery.

STUDY DESIGN: Retrospective analysis of outcome in terms of incidence of surgery for adolescent idiopathic scoliosis during a period when bracing was not practiced. OBJECTIVES: To determine whether centers with an active bracing policy have lower numbers undergoing surgery for adolescent idiopathic scoliosis than a center where nonintervention is the practice. BACKGROUND DATA: Two major recent publications have claimed that bracing significantly improves the outcome in adolescent idiopathic scoliosis. However, one had no control subjects and the other did not examine the final status of the subjects under review. While statistically significant differences in progression have been observed, what will convince patients to submit to an onerous treatment is the conviction that it will make a substantial difference, such as the avoidance of surgery. METHODS: Since 1991, bracing has not been recommended for children with adolescent idiopathic scoliosis at this center. The scoliosis database was searched for patients with adolescent idiopathic scoliosis who were at least 15 years of age at last review and who had adequate documentation of curve parameters. The incidence of surgery was compared with that of published data from other centers. RESULTS: A total of 153 children, 11 boys and 142 girls, fitted the criteria. Forty-three of these (28.1%) have undergone surgery. This was not statistically different from the surgery rate reported from an active bracing center. CONCLUSIONS: If bracing does not reduce the proportion of children with adolescent idiopathic scoliosis who require surgery for cosmetic improvement of their deformity, it cannot be said to provide a meaningful advantage to the patient or the community. Recent studies notwithstanding, the question of the efficacy of orthoses in idiopathic scoliosis remains unresolved.

Left thoracic curve patterns and their association with disease.

STUDY DESIGN: Analysis of clinical database material collected prospectively. OBJECTIVE: Examination of the association between lateralization of scoliotic curves and the existence of underlying disease. SUMMARY OF BACKGROUND DATA: It has been suggested that left thoracic scoliosis configurations are intrinsically pathologic, whereas the more usual right curve is, in a sense, "normal." METHODS: Research-based records were analyzed. Scoliosis configuration, patient gender, and diagnostic group were correlated. The results were interpreted within a biologic framework. RESULTS: Congenital and infantile idiopathic scoliosis showed a random right-left curve distribution. In older age groups, boys were more likely to have a left thoracic curve and to have underlying disease, but there was no association between the two. In girls, occurrence in childhood itself and left thoracic patterns within that group were associated with disease. Nevertheless, most curves were in the right thoracic pattern, regardless of cause. CONCLUSIONS: Although an association exists between left thoracic curves and disease, it is not strong enough to determine who should be intensively investigated, to the exclusion of other clinical findings, and it seems inappropriate for a different approach to be adopted on the basis of scoliosis pattern alone. Gender in males and age at occurrence in females are more important risk factors than in scoliosis configuration. All new cases of scoliosis treated by a physician warrant equally meticulous assessment, with more sophisticated investigative techniques where indicated by the complete clinical picture, of which curve lateralization is only a part. Biologic theories of left and right are more capable of dealing with the phenomenon of scoliosis lateralization than are simple mechanics or concepts of specific diseases.

Scoliosis and developmental theory: adolescent idiopathic scoliosis.

STUDY DESIGN: Statistical analysis of maturity and asymmetry criteria in adolescent idiopathic scoliosis. OBJECTIVES: To explore the hypothesis that scoliosis is a manifestation of developmental destabilization under physiologic stress. BACKGROUND: Advances in genetics and theoretical biology have broadened the understanding of morphogenesis and the controlling mechanisms for the development of the adult form. The morphologic genome can be viewed as a cybernetic control system, and the homeobox genes can be viewed as the master controls for the specific subroutines. Deformity will occur from a faulty "program" or a disturbance in the running of that program. An early and subtle indication of such an occurrence is failure of bilateral symmetry. METHODS: An analysis of variance in Cobb angle, age at diagnosis, and apical site in 327 girls with spinal curves 5 degrees or greater according to prospectively maintained scoliosis screening records was performed. Dermatoglyphics were compared in 114 female control individuals and 164 female patients with adolescent idiopathic scoliosis (minimum Cobb angle, 10 degrees), and then by subdivision into school screening (n = 86) and general clinic referrals (n = 78). RESULTS: Girls from the screening program (from the years 1979-1990) had statistically significant associations between age and apical vertebra, suggesting an age-deformity relationship independent of maturation and growth spurt. Girls with adolescent idiopathic scoliosis from a later cohort, both screened and unscreened, had increased directional asymmetry, as previously reported. There was a statistically significant increase in fluctuating asymmetry in general clinic referrals when compared with school screening referrals. CONCLUSIONS: Developmental instability can explain adolescent idiopathic scoliosis as part of wider developmental theory without the necessity of a disease process in the etiology. The differences between screening and general clinic referrals suggest the need for natural history studies, and treatment protocols also should consider the provenance of the individuals described.

Fluctuating asymmetry and vertebral malformation. A study of palmar dermatoglyphics in congenital spinal deformities.

STUDY DESIGN: Prints of palmar dermatoglyphics (epidermal ridges) of individuals with congenital vertebral anomaly were compared, using symmetry criteria, with those of healthy control individuals. Asymmetries have been reported in adolescent idiopathic scoliosis and, from other centers, in other congenital anomalies, such as cleft lip and palate. Application of these methods to congenital vertebral anomaly seemed promising. OBJECTIVES: To challenge the hypothesis that, in congenital vertebral anomaly, epigenesis was disrupted by nonspecific physiologic stress during the embryonic period, resulting in anatomic malformations. SUMMARY OF BACKGROUND DATA: Dermatoglyphics (palmar epidermal ridges) are formed at the end of the embryonic period under genetic control and do not change thereafter. They thus give an indication of the stability or otherwise of development at that early stage. This led to the hypothesis that congenital vertebral anomaly results from destabilization of genetic developmental control in the embryonic period. METHODS: The dermatoglyphics of 126 healthy control individuals and 99 people with congenital vertebral anomaly were compared quantitatively, using right-left differences of atd angles and ab, bc, and cd ridge counts. RESULTS: Fluctuating asymmetry (a significantly increased variance about the mean) was observed in individuals with congenital vertebral anomaly. This is a measure of instability of genetic development processes and the increased probability that these processes will be destabilized by environmental stress during ontogeny. They also showed an increased incidence of ridge dissociation, suggestive of a generalized insult during the embryonic period. CONCLUSIONS: These findings suggest that congenital vertebral anomalies arise from a nonspecific insult during the embryonic period that destabilizes the developmental control systems and may result in congenital malformations of any organ undergoing concurrent epigenesis.

Adolescent idiopathic scoliosis and cerebral asymmetry. An examination of a nonspinal perceptual system.

STUDY DESIGN: This study analyzed the asymmetry of a nonspinal sensory system, comparing healthy children and those with adolescent idiopathic scoliosis. OBJECTIVES: To test the hypothesis that differences in neurologic functioning that have been observed in idiopathic scoliosis are confined to motor organization and that the etiology thus is a defect solely of the motor cortex. SUMMARY OF BACKGROUND DATA: Recent reports associating scoliosis convexity with equilibrium control, central processing, handedness, and motor lateralization have suggested that idiopathic scoliosis is connected causally with the motor cortex. METHODS: Dichotic listening tests were performed on 20 healthy children and 31 children with adolescent idiopathic scoliosis. This tests perceptual asymmetry, and thus the organization of cognitive processing in the brain, a higher function that is not associated with posture or motor function. RESULTS: Subjects with scoliosis were significantly more lateralized for linguistic processing than the control group, indicating they had a greater degree of left-right asymmetry throughout their cortical organization. CONCLUSION: In adolescent idiopathic scoliosis, the organization of the entire brain was more strongly lateralized than in subjects without scoliosis. It is unlikely that this caused or was caused by the spinal curvature. Subjects with adolescent idiopathic scoliosis showed generalized asymmetry of many functions and structures. An examination at the level of morphology and development is proposed.

School scoliosis screening and the United States Preventive Services Task Force. An examination of long-term results.

STUDY DESIGN: Analysis of scoliosis screening in Dublin (1979-1990) of patients who passed significant levels (25 degrees and 40 degrees) and received orthotic treatment or surgery. OBJECTIVES: To reexamine the basis of school scoliosis screening. SUMMARY OF BACKGROUND DATA: The United States Preventive Services Task Force questioned the validity of school screening for adolescent idiopathic scoliosis because there is insufficient scientific evidence to justify it. METHODS: New entrants (1986-87) to the screening program were used to test the validity of the screening methods. The total screened population, proportions reaching significant Cobb angles or undergoing treatment, were compared across the time period. RESULTS: The sensitivity of the forward bend test in detecting or predicting 40 degrees scoliosis was 0.83, the specificity was 0.99, and the predictive value was 0.08. The proportion prescribed braces declined significantly (P < 0.01), but there was no significant change in those with scoliosis greater than 24 degrees (0.18%) or 39 degrees (.08%) nor was there a significant change in the numbers needing surgery (.045%). CONCLUSIONS: The incidence of significant scoliosis and of surgery is low and independent of changes in bracing policy. The validity of screening to cause significant change in prevalence must be challenged.

Adolescent idiopathic scoliosis as developmental instability.

Adolescent idiopathic scoliosis is the most common spinal deformity affecting children, with a prevalence from mass screening programmes of 1-3%. Despite centuries of study, it remains a problem with no generally accepted theory of aetiology, and disagreement on its natural history and management. Because the deformity consists ultimately of gross left-right asymmetry, a study was undertaken to test the hypothesis that it might be a manifestation of developmental instability. Palmar dermatoglyphics in 112 normal subjects, 62 with non-scoliosis trunk asymmetry and 85 with defined adolescent idiopathic scoliosis were examined and both the absolute right-left difference and the ratio of this to the total were considered. There was increased fluctuating asymmetry of atd difference in those with any asymmetry, scoliotic or not, and increased directional asymmetry of ab and cd ridge counts only in those with pure scoliosis. This suggests that, at adolescence, developmental instability may result in a loss of symmetry in growth, and that in the presence of an increased developmental left-right gradient, this may be of sufficient severity to be classified as deformity and come to the attention of orthopaedic surgeons. This interpretation changes the focus of many previous observations on scoliosis and raises the prospect that developmental stability in humans has relevance to problems hitherto restricted to clinical practice.

Left thoracic scoliosis configurations. Why so different?

STUDY DESIGN: Patients in the scoliosis screening database were analyzed with respect to curve convexity, severity, and outcome, using standard statistical methods. OBJECTIVES: This study assessed whether left thoracic scoliosis is always pathologic and inquired why this is the case. SUMMARY OF BACKGROUND DATA: Left thoracic scoliosis is more significant than the usual right thoracic pattern, but evidence in the literature is circumstantial. METHODS: Prospectively collected data from 1979-1990 was analyzed in the natural history database of the school screening program. RESULTS: Right thoracic pattern was observed in 421 girls, and left thoracic pattern was present in 125 girls. The minimum age at diagnosis was 10 years and the Cobb angle was > 4 degrees. Primary left thoracic patterns were statistically smaller and less progressive. CONCLUSIONS: The left pattern of scoliosis in the absence of overt neuropathology carries a benign prognosis. This contradictory observation is examined in the light of biological asymmetry.