Scoliosis in the community.

Screening for scoliosis at schools has become more and more popular despite the lack of knowledge concerning the clinical course of idiopathic scoliosis. An epidemiological study of 5303 schoolchildren showed three types of scoliosis in the community: (1) pelvic tilt scoliosis (an inconsequential deformity caused by an inequality in the length of the legs but accounting for almost 40% of curves detected); (2) spinal scoliosis (a minor asymmetry of the spine in the coronal plane that tends to remain static or to resolve and which may be normal in growing children, accounting for the remaining 60%); and (3) progressive scoliosis (10% of the spinal scolioses measuring 10 degrees or more that progress by 5 degrees or more a year). Progressive scoliosis resembles idiopathic scoliosis because in girls with right thoracic curves the potential for progression is appreciable. Until the natural history is better established growing awareness in the community of spinal deformity should help earlier detection, and screening should be directed towards providing subjects for further epidemiological work.     

Pathogenesis of adolescent idiopathic scoliosis in girls - a double neuro-osseous theory involving disharmony between two nervous systems, somatic and autonomic expressed in the spine and trunk: possible dependency on sympathetic nervous system and hormones with implications for medical therapy

Anthropometric data from three groups of adolescent girls - preoperative adolescent idiopathic scoliosis (AIS), screened for scoliosis and normals were analysed by comparing skeletal data between higher and lower body mass index subsets. Unexpected findings for each of skeletal maturation, asymmetries and overgrowth are not explained by prevailing theories of AIS pathogenesis. A speculative pathogenetic theory for girls is formulated after surveying evidence including: (1) the thoracospinal concept for right thoracic AIS in girls; (2) the new neuroskeletal biology relating the sympathetic nervous system to bone formation/resorption and bone growth; (3) white adipose tissue storing triglycerides and the adiposity hormone leptin which functions as satiety hormone and sentinel of energy balance to the hypothalamus for long-term adiposity; and (4) central leptin resistance in obesity and possibly in healthy females. The new theory states that AIS in girls results from developmental disharmony expressed in spine and trunk between autonomic and somatic nervous systems. The autonomic component of this double neuro-osseous theory for AIS pathogenesis in girls involves selectively increased sensitivity of the hypothalamus to circulating leptin (genetically-determined up-regulation possibly involving inhibitory or sensitizing intracellular molecules, such as SOC3, PTP-1B and SH2B1 respectively), with asymmetry as an adverse response (hormesis); this asymmetry is routed bilaterally via the sympathetic nervous system to the growing axial skeleton where it may initiate the scoliosis deformity (leptin-hypothalamic-sympathetic nervous system concept = LHS concept). In some younger preoperative AIS girls, the hypothalamic up-regulation to circulating leptin also involves the somatotropic (growth hormone/IGF) axis which exaggerates the sympathetically-induced asymmetric skeletal effects and contributes to curve progression, a concept with therapeutic implications. In the somatic nervous system, dysfunction of a postural mechanism involving the CNS body schema fails to control, or may induce, the spinal deformity of AIS in girls (escalator concept). Biomechanical factors affecting ribs and/or vertebrae and spinal cord during growth may localize AIS to the thoracic spine and contribute to sagittal spinal shape alterations. The developmental disharmony in spine and trunk is compounded by any osteopenia, biomechanical spinal growth modulation, disc degeneration and platelet calmodulin dysfunction. Methods for testing the theory are outlined. Implications are discussed for neuroendocrine dysfunctions, osteopontin, sympathoactivation, medical therapy, Rett and Prader-Willi syndromes, infantile idiopathic scoliosis, and human evolution. AIS pathogenesis in girls is predicated on two putative normal mechanisms involved in trunk growth, each acquired in evolution and unique to humans.     

褪黑素在特发性脊柱侧凸发生发展中的作用

尽管众多学者对青少年特发性脊柱侧凸近行了广泛研究,但其病因至今仍然不清楚。通过将雏鸡松果体切除,可诱导出与人类特发性脊柱侧凸患者具有相似解剖学特征的脊柱畸形。进一步实验发现,松果体切除术亦可以使2足鼠发生脊柱侧凸。因此,褪黑素(松果体主要的分泌产物)水平的降低与特发性脊柱侧凸的发生密切相关。许多学者对青少年特发性脊柱侧凸患者的褪黑素水平进行了测定,但并未得出一致的结论。目前,褪黑素在青少年特发性脊柱侧凸发生中的作用,还存在争议,需要进一步的研究。     

Teleosts as models for human vertebral stability and deformity

Vertebral development is a dynamic and complicated process, and defects can be caused by a variety of influences. Spinal curvature with no known cause (idiopathic scoliosis) affects 2-3% of the human population. In order to understand the etiology and pathogenesis of complex human skeletal defects such as idiopathic scoliosis, multiple models must be used to study all of the factors affecting vertebral stability and deformity. Although fish and humans have many of the same types of offenses to vertebral integrity, they have been overlooked as a resource for study. The most common morphological deformity reported for fish are those that occur during the development of the spinal system, and as with humans, curvature is a common morphological consequence. Here we review spinal curvature in teleosts and suggest that they are an unexploited resource for understanding the basic elements of vertebral stability, deformity, development and genetics. Fish can be a value to vertebral research because they are tractable, have a diversity of non-induced vertebral deformities, and substantial genomic resources. Current animal models lack non-induced deformities and the experimental tractability necessary for genetic studies. The fact that fish are free of an appendicular skeleton should allow for analysis of basic spinal integrity without the biomechanical constraints observed in quadrupedal and bipedal models. To illustrate the point we review human idiopathic scoliosis and the potential contribution teleosts can make for the identification of causes, risk factors, and treatment options.     

Specification of left-right asymmetry in the embryonic gut of Drosophila

Most animals exhibit stable left-right asymmetries in their body. Although significant progress has been made in elucidating the mechanisms that set up these asymmetries in vertebrates, nothing is known about them in Drosophila. This is usually attributed to the fact that no reversals of stable left-right asymmetries have been observed in Drosophila, although relevant surveys have been carried out. We have focused on the asymmetry of the proventriculus in the embryonic gut of Drosophila, an aspect of left-right asymmetry that is extremely stable in wild-type flies. We show that this asymmetry can be reversed by mutations in the dicephalic and wunen genes, which also cause reversals in the antero-posterior axis of the embryo relative to its mother. This is the first observation to suggest that left-right asymmetries in Drosophila can be reversed by genetic/developmental manipulations. It also suggests that maternal signals may initiate the specification of some left-right asymmetries in the embryo.     

The three-dimensional easy morphological (3-DEMO) classification of scoliosis – Part III, correlation with clinical classification and parameters

Background

The shape of the torso in patients with idiopathic scoliosis is considered to reflect the shape of the vertebral column, however the direct correlation between parameters describing clinical deformity and those characterizing radiological curvature was reported to be weak. It is not clear if the management proposed for scoliosis (physiotherapy, brace, surgery) affects equally the shape of the axial skeleton and the surface of the body. The aim of the study was to compare clinical deformity of (1) idiopathic scoliosis girls being under brace treatment for radiological curves of 25 to 40 degrees and (2) non treated scoliotic girls matched for age and Cobb angle.

Methods

Cross-sectional study of 24 girls wearing the brace versus 26 girls without brace treatment, matched for age and Cobb angle. Hypothesis: Patients wearing the brace for more than 6 months, when comparing to patients without brace, may present different external morphology of the trunk, in spite of having similar Cobb angle. Material. Inclusion criteria: girls, idiopathic scoliosis, growing age (10–16 years), Cobb angle minimum 25°, maximum 40°. The braced group consisted of girls wearing a TLSO brace (Cheneau) for more than 6 months with minimum of 16 hours per day. The non-braced group consisted of girls first seen for their spinal deformity, previously not treated. The groups presented similar curve pattern. Methods. Scoliometer exam: angle of trunk rotation at three levels of the spine: upper thoracic, main thoracic, lumbar or thoracolumbar. The maximal angle was noted at each level and the sum of three levels was calculated. Posterior trunk symmetry index (POTSI) and Hump Sum were measured using surface topography.

Results

Cobb angle was 34.9° ± 4.8° in braced and 32.7° ± 4.9° in un-braced patients (difference not significant). The age was 14.1 ± 1.6 years in braced patients and 13.1 ± 1.9 years in un-braced group (p = 0.046). The value of angle of trunk rotation in the main curvature was 8.4° ± 2.7°in braced and 11.4° ± 2.7° in un-braced patients (difference extremely significant, p = 0.0003). The value of the sum of angles of trunk rotation at three levels of the trunk was 12.8° ± 4.6° in braced and 16.5° ± 3.8° in un-braced patients (difference very significant, p = 0.0038). The POTSI did not differ significantly between the groups (p = 0.78), the Hump Sum values were not quite different (p = 0.07).

Conclusion

(1) Adolescent girls wearing the brace for idiopathic scoliosis of 25 to 40 degrees of Cobb angle, reveal smaller clinical rotational deformity of their back than non-treated girls having similar radiological deformity. (2) evaluation of the results of treatment for idiopathic scoliosis should consider parameters describing both clinical and radiological deformity.     

Case study: Scoliosis in a Bonobo (Pan paniscus)

Differential diagnosis of observed morphological features on an adult male bonobo skeleton was consistent with idiopathic scoliosis. Directional asymmetry was an order of magnitude higher compared with asymptomatic skeletons. This possible case of idiopathic scoliosis contributes to data that suggest a weaker tie between bipedalism and scoliosis than previously hypothesized.     

Fluctuating and directional asymmetry in natural bird populations exposed to different levels of habitat disturbance, as revealed by mixture analysis

While bilateral trait asymmetry is widely recognized to estimate developmental instability, much controversy exists over which types of asymmetry (fluctuating, directional, and/or antisymmetry) to use. Recently it has been hypothesized that the three types are strongly interrelated, and that increased developmental instability may be reflected in a transition from fluctuating to directional asymmetry and/or antisymmetry. Alternatively, habitat disturbance might change the genetic expression of directional asymmetry. We present herein the first empirical evidence for stress-mediated shifts in types of asymmetry in natural populations, by using mixture analysis to model tarsus asymmetry in bird populations exposed to different levels of habitat disturbance. Observed asymmetry patterns almost exclusively consisted of true fluctuating asymmetry in the least disturbed populations, but became progressively mixed with directional asymmetry under increasing disturbance. Failing to unravel these mixtures of different forms of asymmetry may have critical implications for the analysis and interpretation of asymmetry data.     

Left-right asymmetry of fly wings and the evolution of body axes.

The body plan of Drosophila, and presumably that of other insects, develops under the control of anterio-posterior and dorsal ventral axes, but no evidence for a left-right axis has yet been found. We used geometric morphometrics to study the wings in three species of flies: Drosophila melanogaster, Musca domestica and Glossina palpalis gambiensis. In all three species, we found that both size and shape showed subtle, but statistically significant directional asymmetry. For size, these asymmetries were somewhat inconsistent within and between species, but for shape, highly significant directional asymmetry was found in all samples examined. These systematic left-right differences imply the existence of a left-right axis that conveys distinct positional identities to the wing imaginal discs on either body side. Hence, the wing discs of Drosophila may be a new model to study the developmental genetics of left-right asymmetry. The asymmetries of shape were similar among species, suggesting that directional asymmetry has been evolutionarily conserved since the three lineages diverged. We discuss the implications of this evolutionary conservatism in conjunction with results from earlier studies that showed a lack of genetic variation for directional asymmetry in Drosophila.     

Fluctuating asymmetry and stress in a medieval Nubian population

Fluctuating asymmetry is commonly used as a bioindicator of developmental stress. This study addresses asymmetry under nutritional/systemic stress in the human craniofacial skeleton and its utility as an indicator of developmental instability. Crania from the diachronic Christian cemeteries at Kulubnarti (Sudanese Nubia) were chosen as a model for nutrition/systemic stress. Previous studies indicate that individuals from the Early Christian cemetery were subjected to greater developmental stress when compared with individuals from the Late Christian cemetery. Therefore, crania from the Early Christian cemetery should display a greater magnitude of fluctuating asymmetry than crania from the Late Christian cemetery. Thirty adult crania of comparable age and sex were selected from each population. Landmark coordinates were digitized in two separate trials and averaged to minimize error. Euclidean distance matrix analysis (EDMA) was used to measure and compare the magnitude of fluctuating asymmetry in each sample. Results indicate that crania from the Early Christian cemetery display greater amounts of fluctuating asymmetry than those from the Late Christian cemetery, as predicted. The degree of fluctuating asymmetry for each linear distance is highly correlated between the cemeteries, suggesting that all humans may share common patterns of fluctuating asymmetry in the skull. In contrast, there is little correlation between magnitude of fluctuating asymmetry and length of linear distance, between-subject variability, or measurement error. These results support the hypothesis that poor nutrition/systemic stress increases developmental instability in the human skull and that increased fluctuating asymmetry constitutes morphological evidence of this stress.     

Ear examination

Adolescent idiopathic scoliosis is the single most common form of spinal deformity seen in orthopedic practice. Our knowledge about the epidemiology, etiology, natural history, and treatment has recently increased dramatically. The incidence of small curves is rather high (2% of the population), whereas severe curves are much less common (<0.1%), but we cannot always predict which curve will progress. Abnormalities of the neuromuscular system and of calcium metabolism, and certain growth, genetic, and mechanical factors may all play roles in the pathogenesis of the disorder. The physiologic secondary effects of severe scoliosis relate to restrictive lung disease, but most patients do not have a deformity great enough to affect their cardiorespiratory function. The psychological and social effects of scoliosis are significant for patients but difficult to quantitate. For most patients with moderate scoliosis—that is, more than 25 to 30 degrees—treatment with an underarm brace or electrical stimulation is adequate to “control” progression of the curve. Surgical fusion allows actual correction of the curve but is indicated in only a small percentage of patients—usually those with more than 50 degrees of deformity.     

Evolution of floral symmetry

Floral monosymmetry, which is conspicuous and prominent in many angiosperms, has attracted much attention from both developmental geneticists and pollination biologists. A combined evolutionary biological approach to studying floral monosymmetry in the Lamiales, the order that contains the model plant Antirrhinum, is just beginning to take shape. In contrast, floral left-right asymmetry has largely been neglected, although it is much in discussion in animal biology, probably because in flowers (unlike in animals) left-right asymmetry is not predominant. Nevertheless, there are patterns in the evolution of floral left-right asymmetry that are interesting enough to be addressed by developmental genetics. These are the direction of contortion in flowers with contort petal aestivation, and the direction of deflection of pollination organs in groups with enantiostylous flowers or in some groups with enclosed pollination organs, such as beans (Phaseolinae, Fabaceae) or louseworts (Pedicularis, Orobanchaceae).     

Is spinal neuromuscular function asymmetrical in adolescents with idiopathic scoliosis compared to those without scoliosis?: A narrative review of surface EMG studies

Adolescent idiopathic scoliosis (AIS) is a three-dimensional spinal deformity occurring between ages of 10–18 years. We aimed to present a reasoned synthesis of the published evidence for and against asymmetrical paraspinal muscle activation in AIS. PubMed and Embase databases were searched using terms: adolescent idiopathic scoliosis AND electromyogra* (EMG). Identified studies (n = 94) were screened for eligibility. We identified 16 studies, from which 136 EMG outcome measures contributed to the review.For EMG onset, one of two studies provided evidence of earlier muscle activation on the convex compared to concave side of the spine, particularly in those with progressive AIS. For EMG amplitude, 43 outcome measures provided evidence of convex > concave activation, 85 outcomes supported no difference between sides, and 8 outcomes supported concave > convex activation. Greater activity on the convex than concave side was more commonly demonstrated at the scoliosis curve apex level, in people with single right thoracic [progressive] curves, during postural tasks.Further research is needed to determine the relationships between muscle activity asymmetry and spinal curve parameters in a variety of motor tasks. Recommendations are provided to improve methodological quality for future studies of spinal neuromuscular function in AIS, as well as more comprehensive and transparent reporting of methods and results.     

Analysis of the interaction between vertebral lateral deviation and axial rotation in scoliosis

There is a lack of clear biomechanical analyses to explain the interaction of the lateral and axial deformity of the spine in idiopathic scoliosis. A finite element model which represented an isolated ligamentous spine with realistic elastic properties and idealized geometry was used to analyse this interaction. Three variations of this model were used to investigate two different hypotheses about the etiology of scoliosis and to define the forces required to produce a scoliosis deformity. The first hypothesis is that coupling within a motion segment produces the interaction between lateral deviation and axial rotation. The second hypothesis is that posterior tethering by soft tissues in the growing spine produces the observed interaction. Modeling of both hypotheses failed to produce the clinically observed pattern of interaction. Therefore, to find which biomechanical forces were required to produce an idealized scoliosis, prescribed displacements were applied to the model. Production of a double curve scoliosis of 10 degrees Cobb angles required lateral forces on the order of 20 N acting 40 mm anterior to the vertebral body centers. There do not appear to be any anatomic structures capable of producing such forces. Therefore, it seems unlikely that scoliosis deformity can be explained in terms of forces acting on the spine, and understanding of its origins may come from examination of other mechanisms such as asymmetric thoracic growth, or asymmetric vertebral development.     

Fluctuating asymmetry in farmed Atlantic salmon (Salmo salar) juveniles: also a maternal matter?

Developmental stability reflects the degree to which phenotypic expression is unaffected by random accidents or developmental noise. Developmental stability may be measured by phenodeviance or fluctuating asymmetry (FA), and estimation of developmental stability has attracted substantial interest because it appears to represent a relatively simple method to identify sub lethal stress exposure and to assess animal welfare. As a part of a long-term study, the work presented here primarily aimed to investigate impacts on developmental instability in farmed salmon offspring ten months post hatch attributable to maternal cortisol administration prior to spawning and mild hyperthermia exerted during incubation. Main results show that maternal cortisol enhancement increased the level of FA in pectoral and pelvic fins, but did not affect the frequency of malformations in offspring. Mild hyperthermia during incubation increased weight and fork length and also increased pelvic fin FA. Malformed fish were heavier and longer than the normal ones, and pelvic fin asymmetry was positively related to condition factor. These results illustrate plausible lasting impacts on offspring development due to the maternal endocrinological state at spawning and indicate that developmental instability in farmed salmon juveniles may mirror aspects of the broodstock’s housing conditions.     

Measuring anterior trunk deformity in scoliosis: development of asymmetry parameters using surface topography (a pilot study)

Background

Clinicians who assess and treat patients for scoliosis typically use parameters that are all visible from the posterior view. Radiographs assess the internal spinal deformity, but do not directly evaluate body shape, either posterior or anterior. This is problematic, as the patient is most concerned about the way they appear in the mirror. An objective set of anterior measurements is needed to help quantify the anterior asymmetry that is present in scoliosis.

Methods

The design of this system of assessment was developed as a consensus of thinking from four points of view. A spine surgeon provided the musculoskeletal structural perspective. A plastic surgeon specializing in breast reconstruction provided the aesthetic and soft tissue perspective. A surface topography researcher provided the imaging perspective, and a scoliosis patient provided the self-perception and emotional perspective.Using an iterative process, a series of potential measurement parameters using surface topography measurements were considered, debated, and ultimately selected to be part of a system of measurement that provides an overall assessment of anterior trunk asymmetry.

Results

An anterior surface topography scan in the relaxed, standing position was taken of the scoliosis patient. The computer provides a 3D topographical model that is used to complete measurements that can be combined to achieve an Anterior Aesthetic Deformity Score. Shoulder parameters, including shoulder height difference and shoulder slope difference, make up 40 % of the total score. Breast asymmetry, including nipple height difference and sternal notch-to-nipple distance, make up 30 % of the total score. Waist asymmetry makes up the final 30 % of the score, providing an objective and quantifiable measure of anterior trunk deformity.

Conclusions

These measurements provide an objective, systematic evaluation of anterior trunk asymmetry that can be used in the assessment of patients with scoliosis. Clinical research should now be done to validate this system and show that it is reproducible in a variety of settings and patients.

     

Reconstruction of Laser-scanned 3D Torso Topography and Stereoradiographical Spine and Rib-cage Geometry in Scoliosis

Assessments of scoliosis are routinely done by means of clinical examination and full spinal x-rays. Multiple exposure to ionization radiation, however, can be hazardous to the child and is costly. Here, we explain the use of a noninvasive imaging technique, based on laser optical scanning, for quantifying the three-dimensional (3D) trunk surface topography that can be used to estimate parameters of 3D deformity of the spine. The laser optical scanning system consisted of four BIRIS laser cameras mounted on a ring moving along a vertical axis, producing a topographical mapping of the entire torso. In conjunction with the laser scans, an accurate 3D reconstruction of the spine and rib cage were developed from the digitized x-ray images. Results from 14 scoliotic patients are reported. The digitized surfaces provided the foundation data to start studying concordance of trunk surface asymmetry and spinal shape in idiopathic scoliosis.     

Reconstruction of laser-scanned 3D torso topography and stereoradiographical spine and rib-cage geometry in scoliosis

Assessments of scoliosis are routinely done by means of clinical examination and full spinal x-rays. Multiple exposure to ionization radiation, however, can be hazardous to the child and is costly. Here, we explain the use of a noninvasive imaging technique, based on laser optical scanning, for quantifying the three-dimensional (3D) trunk surface topography that can be used to estimate parameters of 3D deformity of the spine. The laser optical scanning system consisted of four BIRIS laser cameras mounted on a ring moving along a vertical axis, producing a topographical mapping of the entire torso. In conjunction with the laser scans, an accurate 3D reconstruction of the spine and rib cage were developed from the digitized x-ray images. Results from 14 scoliotic patients are reported. The digitized surfaces provided the foundation data to start studying concordance of trunk surface asymmetry and spinal shape in idiopathic scoliosis.     

FLUCTUATING ODONTOMETRIC ASYMMETRY,MORPHOLOGICAL VARIABILITY,AND GENETIC MONOMORPHISM IN THE CHEETAH ACINONYX JUBATUS

The magnitudes of dimensional variability and fluctuating asymmetry in dental dimensions are reported for a sample of South African cheetah Acinonyx jubatus. To test the hypothesis that elevated levels of variability and asymmetry are associated with the increased developmental instability reported for this species, our results were contrasted to those for two other felids: Felis lybica and F. caracal. These findings suggest that dental dimensions in cheetahs are not significantly more variable or asymmetric. Hence, it is concluded that the cheetah may not be as developmentally unstable as was previously supposed.     

Modification of developmental instability and fitness: Malathion-resistance in the Australian sheep blowfly,Lucilia cuprina

The evolution of resistance to malathion byLucilia cuprina initially results in an increase in fluctuating asymmetry. Resistant flies are at a selective disadvantage, relative to susceptibles, in the absence of the insecticide. A fitness/asymmetry modifier of diazinon-resistant phenotypes ameliorates these effects resulting in malathion-resistant phenotypes of relative fitness and asymmetry similar to susceptibles. For the nine genotypic combinations of the modifier and malathion-resistance alleles, developmental time increases linearly with increasing asymmetry. Percentage egg hatch decreases linearly with increasing asymmetry. The initially disruptive effect of the malathion-resistant allele was partially dominant, the effect of the modifier dominant. The results are discussed in terms of developmental perturbation, asymmetry estimation and relative fitness to consider whether it is adequate to use changes in fluctuating asymmetry alone as measures of developmental instability. It is suggested that in some circumstances antisymmetry may indicate developmental instability and that the diazinon/malathion-resistance systems inL. cuprina may allow the relative importance of genetical and/or environmental developmental perturbations to be ascertained.