How 'idiopathic' is adolescent idiopathic scoliosis? A systematic review on associated abnormalities

Brace-related Stress and Quality of Life Parameters between Chêneau and Boston Braces: A Cross-sectional Comparative Study on Adolescent Idiopathic Scoliosis in Saudi Arabia

OBJECTIVE

Adolescent idiopathic scoliosis (AIS) is the most prevalent spinal deformity affecting healthy children. Although AIS typically lacks symptomatic manifestations, its resultant deformities can affect patients' quality of life (QoL). Evaluating QoL and stress levels is crucial in determining the optimal brace type for AIS patients; however, research comparing the effectiveness of different brace types in this regard is lacking. Therefore, this study aimed to evaluate the impact of Boston versus Chêneau braces on QoL and stress levels in AIS patients.

METHODS

This cross-sectional study was conducted at a medical institution in Riyadh, Saudi Arabia, involving 52 eligible patients selected through stratified random sampling based on type of brace as the main stratum. The inclusion criteria were idiopathic scoliosis, age ≥ 10 years, bracing for at least 3 months, and no history of cancer. QoL was evaluated according to the revised Scoliosis Research Society 22-item questionnaire (SRS-22r) and stress levels according to the eight-item Bad Sobernheim stress questionnaire (BSSQ-Brace). Independent-sample t-tests were used to compare brace-related QoL and stress level according to participants' sex and brace type.

RESULTS

Overall, 32 participants were treated with Boston braces (seven men and 25 women), with a median (IQR) age of 11.00 years (10.00-13.00), and 20 participants were treated with Chêneau braces (three men, 17 women), with a median (IQR) age of 12.50 years (10.00-14.25). The total SRS-22 score was not significantly different between the brace groups (p = 0.158). However, patients in the Boston brace group reported significantly higher satisfaction levels (median = 4.00, IQR = 3.50-4.50) than did those in the Chêneau brace group (median = 3.25, IQR = 2.38-4.13, p = 0.013, moderate effect size = 0.345, 95% CI = 0.060 to 0.590). Furthermore, the BSSQ-brace total score was significantly higher in the Boston brace group (median = 9.00, IQR = 8.00-12.00) than in the Chêneau brace group (median = 7.50, IQR = 4.75-10.00, p = 0.007, moderate effect size = 0.376, 95% CI = 0.130 to 0.590), indicating higher stress levels in the Chêneau brace group.

CONCLUSION

The QoL in AIS patients undergoing brace treatment was comparable across groups. Nonetheless, patients who used Chêneau braces experienced higher stress levels and lower treatment satisfaction rates than did those who used Boston braces. These findings can inform clinical decisions regarding prescription of bracing types and highlight the need for further in-depth research.

The effect of Schroth Best Practice exercises and Cheneau brace treatment on perceptual and cognitive asymmetry in adolescent idiopathic scoliosis with thoracic major curve

BACKGROUND

Adolescent idiopathic scoliosis (AIS) patients have been found to exhibit cortical asymmetry. Although asymmetries in cortical structures have been found in patients with AIS, there has been no research on how conservative treatments affect cerebellar functional organization.

AIMS

This study aimed to examine the impact of conservative treatments on perceptual and cognitive asymmetry in the auditory system assessed by dichotic listening in AIS patients with thoracic major curves.

METHOD

This study involved 30 AIS patients and 21 healthy subjects. The intervention group used a Cheneau brace and performed 18 Schroth Best Practice (SBP) exercise sessions. Auditory lateralization was assessed using the Dichotic Listening Paradigm (DLP) in both groups before and after the intervention.

RESULTS

The 6-week intervention resulted in a significant increase in left ear responses in the force-left condition in the AIS (p < 0.05). Left ear responses were lower in AIS at baseline (p < 0.05). The results at week 6 were similar in all conditions (p > 0.05).

CONCLUSION

The results of this study demonstrated that SBP exercises and Cheneau brace treatment can improve perceptual and cognitive asymmetry in the auditory system in AIS patients with thoracic major curve. Scoliosis-associated changes in the spine and postural control may affect auditory perception by causing adaptations in sensory and motor networks. Future studies are needed to examine the connectivity in brain regions related to motor control and auditory processing after conservative treatment.

TRIAL REGISTRATION

Clinical trials number: NCT06141759.

Prevalence and plasma exosome-derive microRNA diagnostic biomarker screening of adolescent idiopathic scoliosis in Yunnan Province, China

Background

Idiopathic scoliosis significantly affects the physical and mental health of children and adolescents, with varying prevalence rates in different regions. The occurrence of idiopathic scoliosis is associated with genetic regulation and biochemical factors, but the changes in exosome-derived miRNA profiles among idiopathic scoliosis patients remain unclear. This study aimed to determine the prevalence of idiopathic scoliosis in Yunnan Province, China, and identify key exosome-derived miRNAs in idiopathic scoliosis through a cohort study.

Methods

From January 2018 to December 2020, a cross-sectional study on idiopathic scoliosis in children and adolescents was conducted in Yunnan Province. A total of 84,460 students from 13 cities and counties in Yunnan Province participated in a scoliosis screening program, with ages ranging from 7 to 19 years. After confirmation through screening and imaging results, patients with severe idiopathic scoliosis and normal control individuals were selected using propensity matching. Subsequently, plasma exosome-derived miRNA sequencing and RT-qPCR validation were performed separately. Based on the validation results, diagnostic performance analysis and target gene prediction were conducted for differential plasma exosome-derived miRNAs.

Results

The overall prevalence of idiopathic scoliosis in children and adolescents in Yunnan Province was 1.10%, with a prevalence of 0.87% in males and 1.32% in females. The peak prevalence was observed at age 13. Among patients diagnosed with idiopathic scoliosis, approximately 12.8% had severe cases, and there were more cases of double curvature than of single curvature, with thoracolumbar curvature being the most common in the single-curvature group. Sequencing of plasma exosome-derived miRNAs associated with idiopathic scoliosis revealed 56 upregulated and 153 downregulated miRNAs. Further validation analysis confirmed that hsa-miR-27a-5p, hsa-miR-539-5p, and hsa-miR-1246 have potential diagnostic value.

Conclusions

We gained insights into the epidemiological characteristics of idiopathic scoliosis in Yunnan Province and conducted further analysis of plasma exosome-derived miRNA changes in patients with severe idiopathic scoliosis. This study has provided new insights for the prevention and diagnosis of idiopathic scoliosis, paving the way for exploring clinical biomarkers and molecular regulatory mechanisms. However, further validation and elucidation of the detailed biological mechanisms underlying these findings will be required in the future.

Deletion of a conserved genomic region associated with adolescent idiopathic scoliosis leads to vertebral rotation in mice

Adolescent idiopathic scoliosis (AIS) is the most common form of scoliosis, in which spinal curvature develops in adolescence, and 90% of patients are female. Scoliosis is a debilitating disease that often requires bracing or surgery in severe cases. AIS affects 2%-5.2% of the population; however, the biological origin of the disease remains poorly understood. In this study, we aimed to determine the function of a highly conserved genomic region previously linked to AIS using a mouse model generated by CRISPR-CAS9 gene editing to knockout this area of the genome to understand better its contribution to AIS, which we named AIS_CRMΔ. We also investigated the upstream factors that regulate the activity of this enhancer in vivo, whether the spatial expression of the LBX1 protein would change with the loss of AIS-CRM function, and whether any phenotype would arise after deletion of this region. We found a significant increase in mRNA expression in the developing neural tube at E10.5, and E12.5, for not only Lbx1 but also other neighboring genes. Adult knockout mice showed vertebral rotation and proprioceptive deficits, also observed in human AIS patients. In conclusion, our study sheds light on the elusive biological origins of AIS, by targeting and investigating a highly conserved genomic region linked to AIS in humans. These findings provide valuable insights into the function of the investigated region and contribute to our understanding of the underlying causes of this debilitating disease.

Current biomechanical theories on the etiopathogenesis of idiopathic scoliosis

PURPOSE

There is great controversy about the etiologic origin of adolescent idiopathic scoliosis. Multiple theories have been suggested, including metabolic aspects, endocrine dysfunction, neurological central abnormalities, genetic predisposition and epigenetic factors involved in the development of scoliosis. However, there has always been speculations based on human biomechanical behavior.

METHODS

In this article, we performed a literature review on the biomechanical traits of human posture, and the proposed theories that explain the special characteristics present in idiopathic scoliosis.

RESULTS

The current theory on the etiopathogeneis of AIS suggests that dorsally directed shear loads acting on a preexisting axial plane rotation, in a posteriorly inclined sagittal plane of a growing patient, together with disc maturation, collagen quality at this phase of development and immaturity of proprioception, is the perfect scenario to spark rotational instability and create the three-dimensional deformity that defines idiopathic scoliosis.

CONCLUSION

The unique spinal alignment of human bipedalism, gravity and muscle forces acting straight above the pelvis to preserve an upright balance, and the instability of the soft tissue in a period of growth development, is an appealing cocktail to try to explain the genesis of this condition in humans.

Assessment of the functional state of the back muscles in girls with C-shaped low-grade scoliosis in a tensiomyographic image: An observational cross-sectional study

PURPOSE

The study aimed to test the feasibility of using tensiomyography to assess the functional status of the latissimus dorsi and erector spinae muscles in girls with C-shaped low back scoliosis.

MATERIALS AND METHODS

Twenty-five girls aged 13-15 took part in an observational (cross-sectional) study. The examination involved measurements using the tensiomyography method (TMG). Two groups of muscles were tested: latissimus dorsi and erector spinae on the concave and convex side of low-grade scoliosis. The following indicators were analyzed: Td-delay time, Tc-contraction time, and Dm-maximal muscle displacement.

RESULTS

The analysis of Td revealed that values of this variable on the concave side were slightly lower compared to the convex side in both tested groups of muscles. Similarly, Tc values on the concave side were slightly lower than on the convex side of the curvature in both groups of muscles. In the case of Dm, lower displacement values and, consequently, greater muscle rigidity were observed on the concave side of the latissimus dorsi and the convex side of the erector spinae.

CONCLUSIONS

The TMG method can be potentially used to diagnose the functional condition of muscles in patients with low-grade scoliosis. There were differences between the functional condition of the muscles on the concave and convex sides of the curvature.

Impaired autophagy activity-induced abnormal differentiation of bone marrow stem cells is related to adolescent idiopathic scoliosis osteopenia

BACKGROUND

Osteopenia has been well documented in adolescent idiopathic scoliosis (AIS). Bone marrow stem cells (BMSCs) are a crucial regulator of bone homeostasis. Our previous study revealed a decreased osteogenic ability of BMSCs in AIS-related osteopenia, but the underlying mechanism of this phenomenon remains unclear.

METHODS

A total of 22 AIS patients and 18 age-matched controls were recruited for this study. Anthropometry and bone mass were measured in all participants. Bone marrow blood was collected for BMSC isolation and culture. Osteogenic and adipogenic induction were performed to observe the differences in the differentiation of BMSCs between the AIS-related osteopenia group and the control group. Furthermore, a total RNA was extracted from isolated BMSCs to perform RNA sequencing and subsequent analysis.

RESULTS

A lower osteogenic capacity and increased adipogenic capacity of BMSCs in AIS-related osteopenia were revealed. Differences in mRNA expression levels between the AIS-related osteopenia group and the control group were identified, including differences in the expression of LRRC17 , DCLK1 , PCDH7 , TSPAN5 , NHSL2 , and CPT1B . Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed several biological processes involved in the regulation of autophagy and mitophagy. The Western blotting results of autophagy markers in BMSCs suggested impaired autophagic activity in BMSCs in the AIS-related osteopenia group.

CONCLUSION

Our study revealed that BMSCs from AIS-related osteopenia patients have lower autophagic activity, which may be related to the lower osteogenic capacity and higher adipogenic capacity of BMSCs and consequently lead to the lower bone mass in AIS patients.

Application of the Schroth Method in the Treatment of Idiopathic Scoliosis: A Systematic Review and Meta-Analysis

(1) Background: Idiopathic scoliosis can be defined as a complex three-dimensional deformity of the spine and trunk, which occurs in basically healthy children. Schroth scoliosis-specific exercises have shown good results in reducing idiopathic scoliosis progression. This study aimed to critically evaluate the effect size of Schroth's method through a systematic review and meta-analysis. (2) Methods: Four databases were included in the search: PubMed, Cochrane Library, Web of Science, and Google Scholar. The following keywords were used: "Schroth exercise", "idiopathic scoliosis", "Cobb angle", "angle of trunk rotation", and "quality of life". Only articles written in English that met the following criteria were included in our study: subjects who had idiopathic scoliosis, the Schroth method was applied, and Cobb angle or angle of trunk rotation or quality of life as outcomes. (3) Results: Ten randomized controlled trials were included in this study. The effect size of the Schroth exercise ranged from almost moderate to large, for the outcomes used: Cobb angle (ES = -0.492, p ˂ 0.005); ATR (ES = -0.471, p = 0.013); QoL (ES = 1.087, p ˂ 0.001). (4) Conclusions: The current meta-analysis indicates that the Schroth method has a positive effect on subjects with idiopathic scoliosis.

Analysis of the prevalence of asymmetry and muscle tone disorders in the first year of life among youth with idiopathic scoliosis: A retrospective case-control study

BACKGROUND

Not much is known about developmental motor disorders in the first year of life of children diagnosed with idiopathic scoliosis (IS).

OBJECTIVE

This study aimed to compare the occurrence of asymmetry or muscle tone disorders in the first year of life in adolescents with IS and their healthy counterparts.

METHODS

The parents of adolescents with IS and without scoliosis completed a survey on the occurrence of asymmetry, abnormal muscle tone, and physiotherapy in their children in the first year of life. Pearson's chi square test and Cramer's coefficient were used.

RESULTS

The final analysis included 527 surveys completed by parents of adolescents with idiopathic scoliosis (150) and without scoliosis (377). A significantly higher frequency of asymmetry (p= 0.001) and muscle tone disorders (p= 0.001) was noted in adolescents with idiopathic scoliosis. The results also revealed a significant association between scoliosis and asymmetry (p= 0.001), as well as muscle tone (p= 0.001).

CONCLUSIONS

Developmental asymmetry or improper muscle tone in the first year of life could be considered a potential factor in the development of scoliosis; however, this hypothesis should be confirmed in future studies. Infants diagnosed with developmental disorders require systematic observation.

Assessment of changes in the sagittal plane of the spine in girls with adolescent idiopathic scoliosis using the moire method

BACKGROUND

The gold standard in the clinical assessment of the extent of scoliosis is the Cobb method but the analysis also covers the changes that occur within the spine and trunk in relation to the transverse and sagittal planes.

OBJECTIVE

The study aimed to estimate changes in the sagittal plane of the spine in girls with right-sided thoracic adolescent idiopathic scoliosis.

METHODS

The study involved 29 girls with scoliosis (13.6 ± 0.6 years) and 36 healthy girls as the comparison group. The tests included an interview, clinical examination (with the use of Adam's test and the Cobb angle), and examination of shape of the spine surface with the use of the photogrammetric method and the projection moire effect.

RESULTS

Lower values of the thoracic kyphosis parameters were found in the scoliosis group. Significant differences were noted for the parameters of the lumbosacral section α (p= 0.02), thoracolumbar section β (p< 0.001), the upper thoracic section γ (p< 0.001), thoracolumbar and upper thoracic section β+γ (p< 0.001) and the total size of α+β+γ (p< 0.001) curvatures.

CONCLUSIONS

The study showed that with an increase in the angular value of the thoracic curvature, the thoracic kyphosis decreased.

Neurodynamic Functions and Their Correlations with Postural Parameters in Adolescents with Idiopathic Scoliosis

Knowledge about neurodynamic functions of the nervous system (NS) in patients with idiopathic scoliosis (IS) is limited. This study aimed to assess the mechanosensitivity of the NS structures (MNS) in adolescents with IS. The study included 69 adolescents with IS and 57 healthy peers aged 10–15 years. The Upper Limb Neurodynamic Test 1 (ULNT1), straight leg raise (SLR) test, and slump test (SLUMP) were used to assess MNS. The spinal curvatures in the sagittal plane and selected ranges of motion were measured. The data were analysed using the Mann–Whitney U test and Spearman’s rank correlation. Increased MNS assessed by ULNT1 and SLUMP tests was observed in participants with IS. Values of the neurodynamic tests correlated significantly with the sagittal profile of the spine and the mobility of the spine and lower limbs in both groups. In conclusion, increased MNS occurs in adolescents with IS. Therefore, the examination of adolescents with IS should include an assessment of MNS with the neurodynamic tests. Future studies should investigate this issue to better understand the mechanisms that coexist with IS.

Compensatory Ground Reaction Forces during Scoliotic Gait in Subjects with and without Right Adolescent Idiopathic Scoliosis

Although the asymmetries of scoliotic gait in adolescent idiopathic scoliosis (AIS) groups have been extensively studied, recent studies indicated conflicting results regarding the ground reaction forces (GRFs) during gait in subjects with spinal deformity. The asymmetry during the stance phase might be clarified with three-dimensional (3D) compensations of GRFs between similar characteristics of subjects with and without AIS. The purpose of this study was to compare the normalized 3D GRF differences during the stance phase of gait while considering age, BMI, and Cobb angle between subjects with and without right AIS. There were 23 subjects with right convexity of thoracic idiopathic scoliosis and 22 age- and gender-matched control subjects. All subjects were right upper/lower limb dominant, and the outcome measures included the Cobb angles, normalized GRF, and KAI. The mediolateral (M/L) third peak force on the dominant limb decreased in the AIS group (t = 2.58, p = 0.01). Both groups demonstrated a significant interaction with the 3D indices (F = 5.41, p = 0.02). The post-hoc analysis identified that the M/L plane of asymmetry was significantly different between groups. The Cobb angles were negatively correlated with the vertical asymmetry index (r = −0.45, p = 0.03); however, there was no significant correlation with age (r = −0.10, p = 0.65) or body mass index (r = −0.28, p = 0.20). The AIS group demonstrated decreased GRF in the dominant limb M/L plane of the terminal stance phase. This compensatory motion was confirmed by a significant group difference on the M/L plane of the KAI. This KAI of vertical asymmetry correlated negatively with the Cobb angle. The asymmetric load transmission with compensatory vertical reactions was evident due to abnormal loading in the stance phase. These kinetic compensatory patterns need to be considered with asymmetry on the dominant limb when developing rehabilitation strategies for patients with AIS.

22q11.2 Deletion Syndrome as a Human Model for Idiopathic Scoliosis

To better understand the etiology of idiopathic scoliosis, prospective research into the pre-scoliotic state is required, but this research is practically impossible to carry out in the general population. The use of ‘models’, such as idiopathic-like scoliosis established in genetically modified animals, may elucidate certain elements, but their translatability to the human situation is questionable. The 22q11.2 deletion syndrome (22q11.2DS), with a 20-fold increased risk of developing scoliosis, may be a valuable and more relevant alternative and serve as a human ‘model’ for idiopathic scoliosis. This multicenter study investigates the morphology, dynamic behavior, and presence of intraspinal anomalies in patients with 22q11.2DS and scoliosis compared to idiopathic scoliosis. Scoliosis patients with 22q11.2DS and spinal radiography (n = 185) or MRI (n = 38) were included (mean age 11.6 ± 4.2; median Cobb angle 16°) and compared to idiopathic scoliosis patients from recent literature. Radiographic analysis revealed that 98.4% of 22q11.2DS patients with scoliosis had a curve morphology following predefined criteria for idiopathic curves: eight or fewer vertebrae, an S-shape and no inclusion of the lowest lumbar vertebrae. Furthermore, curve progression was present in 54.2%, with a mean progression rate of 2.5°/year, similar to reports on idiopathic scoliosis with 49% and 2.2–9.6°/year. The prevalence of intraspinal anomalies on MRI was 10.5% in 22q11.2DS, which is also comparable to 11.4% reported for idiopathic scoliosis. This indicates that 22q11.2DS may be a good model for prospective studies to better understand the etiology of idiopathic scoliosis.

Investigation of the perceptual and cognitive asymmetry in the auditory system in patients with adolescent idiopathic scoliosis

BACKGROUND

Studies have shown that perceptual and cognitive asymmetries are present in the auditory system in patients with adolescent idiopathic scoliosis (AIS). The Dichotic Listening (DL) paradigm was formerly performed in non-forced (NF) conditions only, and no study has examined the conditions of attention to one ear.

OBJECTIVE

To investigate the perceptual and cognitive asymmetry in the auditory system in patients with AIS as well as the asymmetry changes according to the curvature characteristics of patients with AIS.

METHOD

The DL paradigm was performed on 38 patients with AIS and 10 healthy individuals in all conditions (NF, Forced Right [FR], Forced Left [FL]).

RESULTS

In the NF and FL conditions, the mean number of correct responses for the left ear was significantly lower in patients with AIS than in healthy individuals (p < 0.05). The correct responses for the right ear in the NF condition, right and left ear in the FR condition, and right ear in the FL condition did not show a significant difference between the groups (p > 0.05). Also, there was no difference between patients with AIS with both functional 3-curve and 4-curve (p > 0.05).

CONCLUSION

Our study indicates perceptual and cognitive asymmetry or lateralisation in the auditory system in patients with AIS. The asymmetry might be caused by the inability to direct their attention to the left ear, which is not affected by their curvature type. Further studies are needed to investigate perceptual and cognitive asymmetry behaviour models in the auditory system in patients with AIS.

CLINICAL IMPLICATIONS

Determination of perceptual and cognitive asymmetry in the auditory system may offer a new perspective on conservative treatment protocols for AIS patients. Besides, the DL paradigm can be easily used in patients with AIS as a non-invasive evaluation method in clinics.

Elucidating the inherent features of IS to better understand idiopathic scoliosis etiology and progression

Idiopathic Scoliosis (IS) is a relatively common condition and is estimated to affect as many as 3 % of youth aged 10-17 years (in the United States an estimated approximately 1.4 million otherwise healthy individuals). A clear understanding of the etiology will better direct optimization of evaluation, treatments and therapies, especially early treatments with less invasive methods. A mechanistic explanation of factors combining to initiate and then cause progression of this common condition-- in otherwise healthy pre-teenage and teenage patients--will be discussed. A recent well-designed structured systematic review states that 'strong evidence is lacking for a consistent pattern of occurrence and any abnormality', in other words there is no strong evidence for 'other associated diagnoses' in IS. And so, certain important inherent factors of IS merit greater discussion. Inherent, or intrinsic factors include: a natural susceptibility to develop a lateral and rotational deformity in the immature rapidly growing erect human spine, inherent torsion associated at the induction of deformity, biomechanics related to curve progression, and anthropology/bipedal gait. We know more today about factors related to the condition and its etiology than we have previously. Across multiple disciplines, a mechanistic approach to understanding the etiopathogenesis of IS, allows a reasonable 'theory' for IS etiology and its progression. We will discuss these inherent intrinsic factors in order to further add to our understanding of the theoretical etiopathogenesis. A better understanding of the etiology (and progression) may better direct ways to optimize evaluation, treatments and therapies, especially early treatments with less invasive methods.

What a stranded whale with scoliosis can teach us about human idiopathic scoliosis

Scoliosis is a deformation of the spine that may have several known causes, but humans are the only mammal known to develop scoliosis without any obvious underlying cause. This is called 'idiopathic' scoliosis and is the most common type. Recent observations showed that human scoliosis, regardless of its cause, has a relatively uniform three-dimensional anatomy. We hypothesize that scoliosis is a universal compensatory mechanism of the spine, independent of cause and/or species. We had the opportunity to study the rare occurrence of scoliosis in a whale (Balaenoptera acutorostrata) that stranded in July 2019 in the Netherlands. A multidisciplinary team of biologists, pathologists, veterinarians, taxidermists, radiologists and orthopaedic surgeons conducted necropsy and imaging analysis. Blunt traumatic injury to two vertebrae caused an acute lateral deviation of the spine, which had initiated the development of compensatory curves in regions of the spine without anatomical abnormalities. Three-dimensional analysis of these compensatory curves showed strong resemblance with different types of human scoliosis, amongst which idiopathic. This suggests that any decompensation of spinal equilibrium can lead to a rather uniform response. The unique biomechanics of the upright human spine, with significantly decreased rotational stability, may explain why only in humans this mechanism can be induced relatively easily, without an obvious cause, and is therefore still called 'idiopathic'.

The heritability of coronal and sagittal phenotype in idiopathic scoliosis: a report of 12 monozygotic twin pairs

PURPOSE

One of the pathways through which genetics may act in the causation of idiopathic scoliosis is inheritance of a specific sagittal profile that predisposes for its development. In this study, coronal and sagittal parameters were compared in an international collection of monozygotic twins with idiopathic scoliosis.

METHODS

Twelve monozygotic twin pairs who underwent biplanar radiography for idiopathic scoliosis were systematically identified in existing scoliosis databases in The Netherlands, Sweden, and Denmark. On the first available radiographs, the coronal and sagittal curve parameters (Roussouly and Abelin types, thoracic kyphosis, lumbar lordosis and length of the posteriorly inclined segment) were determined.

RESULTS

In all 12 monozygotic twin pairs, both twins were affected by AIS. Four (33%) twin pairs had similar coronal and sagittal spinal phenotype, whereas two (17%) had different coronal phenotype and similar sagittal profiles, and six (50%) pairs had different coronal as well as sagittal phenotype.

CONCLUSIONS

Analysis of biplanar curve characteristics in monozygotic twins showed that all twin pairs were affected by idiopathic scoliosis. However, only 33% of the pairs had similar coronal and sagittal spinal phenotypes. Based on this limited dataset, the hypothesis can be formulated that besides genetic pre-disposition, the individual (inherited) sagittal profile plays a role in the development of different coronal curve type.

Assessment of trunk muscle activation and intervertebral load in adolescent idiopathic scoliosis by musculoskeletal modelling approach

Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine, the aetiology and pathogenesis of which are poorly understood. Unfortunately, biomechanical data describing trunk muscle activation and intervertebral load, which can contribute to understanding the pathomechanics of the AIS spine, cannot be measured in vivo due to the invasiveness of the procedures. The present study provides the biomechanical characterization of the spinal loads in scoliotic subjects by exploiting musculoskeletal modelling approach, allowing for calculating biomechanical measures in an assigned posture. A spine model with articulated ribcage previously developed in AnyBody software was applied. The predicted outcomes were evaluated in the upright posture, depending on scoliosis severity and curve type, in a population of 132 scoliotic subjects with mild, moderate, and severe scoliosis. Radiographic-based three dimensional reconstruction of vertebral orientations and scaling of body segments and trunk muscle cross-section area guaranteed geometrical subject-specificity. Validation analysis supporting the application of the model was performed. Trunk muscles were found more activated in the convex side of the scoliotic curve, in agreement with reference in vivo measurements, with progressive increase with scoliosis severity. The intervertebral lateral shear was found positively correlated with the severity of the scoliosis, demonstrating that the transferred load is not a priori orthogonal to vertebral endplate in the frontal plane, and thus questioning the assumption of the 'follower load' approach in case of experimental or computational study on the scoliotic spine. The study opens the way for the subject-specific characterization of scoliosis in assigned loading and motion conditions.

Idiopathic Scoliosis as a Rotatory Decompensation of the Spine

Many years of dedicated research into the etiology of idiopathic scoliosis have not led to one unified theory. We propose that scoliosis is a mechanical, rotatory decompensation of the human spine that starts in the transverse, or horizontal, plane. The human spine is prone to this type of decompensation because of its unique and individually different, fully upright sagittal shape with some preexistent transverse plane rotation. Spinal stability depends on the integrity of a delicate system of stabilizers, in which intervertebral disc stiffness is crucial. There are two phases in life when important changes occur in the precarious balance between spinal loading and the disc's stabilizing properties: (i) during puberty, when loads and moment arms increase rapidly, while the disc's "anchor," the ring apophysis, matures from purely cartilaginous to mineralized to ultimately fused to the vertebral body, and (ii) in older age, when the torsional stiffness of the spinal segments decreases, due to disc degeneration and subsequent laxity of the fibers of the annulus fibrosus. During these crucial periods, transverse plane vertebral rotation can increase during a relatively brief window in time, either as adolescent idiopathic or degenerative de novo scoliosis. Much more is known of the biomechanical changes that occur during disc aging and degeneration than of the changing properties of the disc during maturation. © 2020 American Society for Bone and Mineral Research (ASBMR).

IS (Idiopathic Scoliosis) etiology: Multifactorial genetic research continues. A systematic review 1950 to 2017

Objective

IS (idiopathic scoliosis) is a common spinal condition occurring in otherwise completely healthy adolescents. The root cause of IS remains unclear. This systematic review will focus on an update of genetic factors and IS etiology. Though it is generally accepted that the condition is not due to a single gene effect, etiology studies continue looking for a root cause including genetic variants. Though susceptibility from multiple genetic components is plausible based on known family history data, the literature remains unclear regarding multifactorial genetic influences. The objective of this study was to critically evaluate the evidence behind genetic causes (not single gene) of IS through a systematic review and strength-of-study analysis of existing genetic and genome-wide association studies (GWAS). We used the protocol of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

Methods

PubMed was searched for the terms IS, scoliotic, spinal curve, genetic, gene, etiology, polymorphisms. Articles were assessed for risk-of-bias. Level-of-evidence grading was completed via Oxford Centre for Evidence-Based Medicine criteria. The assessment scores factor strength of a study in determining a positive or negative association to a gene etiology.

Results

After screening of 36 eligible papers, 8 relevant studies met inclusion criteria at this time, 3 were in favor of a genetic factor for IS, whereas 5 studies were against it.

Conclusion

Based on the literature analyzed, there is moderate evidence with a low risk-of-bias that does not clarify a genetic cause of IS. The 2 studies in favor of a genetic etiology were completed in homogeneous populations, limiting their generalizability. Relying on a genetic etiology alone for IS may over simplify its multifactorial nature and limit appreciation of other influences.

Association between Bone Turnover Markers, Leptin, and Nutritional Status in Girls with Adolescent Idiopathic Scoliosis (AIS)

The link between scoliotic deformity and bone metabolism in adolescent idiopathic scoliosis (AIS) has not been well researched. Moreover, the data concerning the cross-talk between fat tissue content/hormonal activity and bone markers in this group of patients are lacking. The aim of the study was to assess whether there exists a significant relationship between the severity of AIS and bone turnover markers and leptin levels. The study group was consisted of 77 AIS girls, aged 14.7 ± 2.17 years. Scoliotic curve severity assessed by Cobb’s angle was categorized as mild (10–19°), moderate (20–39°), or severe (≥40°). Corrected height, weight, and waist and hip circumferences were measured and body mass index (BMI), corrected height Z-score, BMI Z-score, and waist/height ratio (WHtR) were calculated for the entire group. Body composition parameters: fat mass (FAT), fat-free mass (FFM), and predicted muscle mass (PMM) were determined using a bioelectrical impedance analyzer. Bone turnover markers (osteocalcin (OC) and amino terminal of collagen cross-links (NTx) and leptin levels were assessed in serum. Multiple regression analysis showed that, OC, NTx (negatively with p < 0.05), and leptin (positively with p < 0.01) were significantly associated with curve severity in AIS girls. Moreover, Cobb’s angle was positively correlated with W/HtR (p < 0.01) and FAT (p < 0.05). One-way analysis of variance (ANOVA) revealed significant differences in leptin (p < 0.05 vs. mild only), OC (p < 0.05 vs. mild and moderate), and W/HtR (p < 0.01 and p < 0.05 vs. mild and moderate, respectively) between the three AIS severity subgroups. OC was significantly lower in the severe AIS subgroup, while leptin and W/HtR were significantly higher. Significant correlations between leptin and anthropometrical parameters as BMI z-score and W/HtR were shown. Leptin level correlated also significantly with BMI z score (p < 0.001), W/HtR (p < 0.0001), and body composition parameters (p < 0.000001). Moreover, there was a significant negative correlation between NTx and leptin level (p < 0.05). Bone metabolism in AIS girls seems to be altered and significantly related to the scoliotic curve severity. Leptin may be a crucial link in the cross-talk between bone turnover and body composition in this group of patients. Further studies concerning interrelationship between nutritional status and bone metabolism in patients with AIS are warranted.

Dysregulation of the ghrelin/RANKL/OPG pathway in bone mass is related to AIS osteopenia

BACKGROUND

Osteopenia has been well documented in adolescent idiopathic scoliosis (AIS), and ghrelin has been shown to have a positive effect on bone metabolism. However, the circulating level of ghrelin is increased in AIS osteopenia, and the relationship between ghrelin and low bone mass in AIS osteopenia remains unclear.

METHOD

A total of 563 AIS and 281 age-matched controls were recruited for this study. Anthropometry and bone mass were measured in all participants. Plasma ghrelin levels were determined by enzyme-linked immunosorbent assay (ELISA) in both AIS and control groups. An improved multiplex ligation detection reaction was performed to analyze single-nucleotide polymorphisms (SNPs). Facet joints were collected and subjected to immunohistochemistry; osteogenic gene and protein expression was also measured. Furthermore, primary cells were extracted from facet joints and bone marrow to observe the response to ghrelin stimulation.

RESULTS

The body mass index was lower and circulating ghrelin was markedly higher in the AIS osteopenia group than in the control group. No significant difference was observed in four ghrelin level-related SNPs between the AIS osteopenia and control groups. RNA and protein analyses revealed higher RANKL/OPG and lower runx2 levels in AIS cancellous bone. Compared with normal primary osteoblasts and BMSCs, AIS osteopenia primary cells were insensitive to the same ghrelin concentration gradient and showed lower osteogenic ability, increases in OPG and decreases in RANKL.

CONCLUSION

Our results indicate that high circulating ghrelin levels may not result from gene variations in AIS osteopenia. Dysregulation of the ghrelin/RANKL/OPG pathway may lead to decreased osteogenic ability of osteoblasts and BMSCs, which may be related to lower bone mass in AIS osteopenia.

Spinal Compressive Forces in Adolescent Idiopathic Scoliosis With and Without Carrying Loads: A Musculoskeletal Modeling Study

The pathomechanisms of curve progression in adolescent idiopathic scoliosis (AIS) remain poorly understood and biomechanical data are limited. A deeper insight into spinal loading could provide valuable information toward the improvement of current treatment strategies. This work therefore aimed at using subject-specific musculoskeletal full-body models of patients with AIS to predict segmental compressive forces around the curve apex and to investigate how these forces are affected by simulated load carrying. Models were created based on spatially calibrated biplanar radiographic images from 24 patients with mild to moderate AIS and validated by comparing predictions of paravertebral muscle activity with reported values from in vivo studies. Spinal compressive forces were predicted during unloaded upright standing as well as standing with external loads of 10, 15, and 20% of body weight (BW) applied to the scapulae to simulate carrying a backpack in the regular way on the back as well as in front of the body and over the shoulder on the concave and convex sides of the scoliotic curve. The predicted muscle activities around the curve apex were higher on the convex side for the erector spinae (ES) and multifidi (MF) muscles, which was comparable to the EMG-based in vivo measurements from the literature. In terms of spinal loading, the implementation of spinal deformity resulted in a 10% increase of compressive force at the curve apex during unloaded upright standing. Apical compressive forces further increased by 50–62% for a simulated 10% BW load and by 77–94% and 103–128% for 15% and 20% BW loads, respectively. Moreover, load-dependent compressive force increases were the lowest in the regular backpack and the highest in the frontpack and convex conditions, with concave side-carrying forces in between. The predictions indicated increased segmental compressive forces during unloaded upright standing, which could be ascribed to the scoliotic deformation. When carrying loads, compressive forces further increased depending on the carrying mode and the weight of the load. These results can be used as a basis for further studies investigating segmental loading in AIS patients during functional activities. Models can thereby be created using the same approach as proposed in this study.

Changes in the Position of the Junctional Vertebrae After Posterior Spinal Fusion in Adolescent Idiopathic Scoliosis: Implication in Risk Assessment of Proximal Junctional Kyphosis Development

BACKGROUND

The development of proximal junctional kyphosis (PJK) after posterior spinal fusion in adolescent idiopathic scoliosis is a major problem. Changes in the global sagittal parameters as they relate to PJK have been reported after surgery, however, the relationships between the changes in the upper-instrumented vertebra (UIV) during and after surgery as they relate to development of PJK have not been quantified. We hypothesize that the compensatory changes in the unfused segments of the spine over time are correlated with the surgically induced changes in the UIV position.

METHODS

Sixty adolescent idiopathic scoliosis patients (with at least 1-year follow-up) who underwent posterior spinal surgery were included retrospectively. Global spinal parameters were calculated using 3-dimensional models of the spine, additional parameters [proximal junctional kyphosis angle (PJKA), cervical lordosis angle] were measured manually before surgery and at 3 postoperative follow-ups. The 3-dimensional position of the vertebral body centroids was calculated for T1, UIV, and lower-instrumented vertebra at all timepoints. The sagittal position of T1, UIV, and lower-instrumented vertebra were correlated to the cervical lordosis, PJKA, lumbar lordosis, and pelvic tilt.

RESULTS

The position of T1 and UIV were significantly more anterior at first erect for patients who developed PJK. The posterior shift of UIV at the most recent follow-up as compared with the preoperative position was significant in both the PJK and non-PJK cohort. A larger anterior shift in UIV at first erect correlated with a larger T1 and UIV posterior shift at the most recent follow-up. At the most recent follow-up, a more posterior position of the UIV correlated with a larger angle of PJKA (P<0.05).

CONCLUSION

Both a larger anterior shift of UIV between preoperative and first erect and a more posterior position of UIV at the most recent follow-up was correlated with a higher PJKA. A larger anterior shift in the position of the UIV after surgery was associated with a higher posterior shift of UIV at the last follow-up. The surgically induced changes in the UIV are an important parameter associated with the development of PJK.

LEVEL OF EVIDENCE

Level IV.

Differential proteome analysis in adolescent idiopathic scoliosis patients with thoracolumbar/lumbar curvatures

BACKGROUND

Although the pathogenesis of adolescent idiopathic scoliosis (AIS) remains unclear, there are little evidences of the pathogenesis in patients with thoracolumbar/lumbar AIS. The purpose of this study was to identify proteins or proteomes that may be causally related to the pathogenesis of AIS with structured thoracolumbar/lumbar curvature using two-dimensional fluorescence difference gel electrophoresis (2D-DIGE).

METHODS

A total of 20 control volunteers and 61 AIS in patients with thoracolumbar/lumbar curvature were included. First, the plasma samples of each five AIS with pure thoracolumbar/lumbar curvature and control samples were subjected to 2D-DIGE analysis. Protein spots that were expressed differently by the AIS and control groups were selected and identified by nanoscale liquid chromatography-tandem mass spectrometry (nanoLC-MS/MS) analysis. To characterize the differently-expressed proteins in AIS patients, we performed functional pathway analysis using the Protein ANalysis THrough Evolutionary Relationships (PANTHER) system. Additionally, the proteins were compared between control and AIS using western blotting. Lastly, prospectively collected 15 control and 41 AIS with thoracolumbar/lumbar curvature samples were compared to the differentially expressed proteins.

RESULTS

A total of 3862 ± 137 spots were detected, of which 11 spots met the criteria when compared with controls. Nine proteins were identified by nanoLC-MS/MS. Functional analysis showed the association of the proteins in AIS patients with blood coagulation using the PANTHER system. Of the proteins, vitamin D binding protein (DBP) significantly correlated with Cobb angle in thoracolumbar/lumbar curvatures. DBP expression of the prospectively collected AIS samples were significantly higher than those of controls (P < 0.05).

CONCLUSIONS

This study suggests that DBP and several coagulation-related proteins may play a role in the pathogenesis of AIS. DBP appears to be a marker of severity of AIS with thoracolumbar/lumbar curvature.

The 22q11.2 deletion syndrome as a model for idiopathic scoliosis - A hypothesis

Adolescent idiopathic scoliosis (AIS), defined as a lateral deviation of the spine of at least ten degrees, is a classic enigma in orthopaedics and affects 1-4% of the general population. Despite (over) a century of intensive research, the etiology is still largely unknown. One of the major problems in all existing AIS research is the fact that most patients come to medical attention after onset of the curve. Therefore, it is impossible to know whether current investigated parameters are causative, or an effect of the scoliosis. Moreover, up until now there is no known animal model that captures the core features of AIS. In order to identify causal pathways leading to AIS we propose another approach, which has been of great value in other medical disciplines: To use a subset of the population, with a higher risk for a certain disease as a "model" for the general population. Such a "model" may allow the identification of causative mechanisms that might be applicable to the general population. The 22q11.2 deletion syndrome (22q11.2DS) is the most common microdeletion syndrome and occurs in ∼1:3000-6000 children and 1:1000 pregnancies. Nearly half of the population of patients with 22q11.2DS develop a scoliosis that in most cases resembles AIS as far as age at onset and curve pattern. We postulate that within 22q11.2DS certain causal pathways leading to scoliosis can be identified and that these are applicable to the general population.

Center of pressure progression patterns during level walking in adolescents with idiopathic scoliosis

The purpose of this study was to determine whether functional walking performance measured with Timed Up-and-Go (TUG) and center of pressure (CoP) progression pattern is different across adolescents with various curve severity of idiopathic scoliosis (IS). The CoP coordinates during a stance phase for self-paced level walking between adolescent with three different severities of IS (mild IS, moderate IS, and severe IS) and age-matched normal subjects were measured with foot pressure measurement. The average data of three trials were compared among groups with repeated measure analysis of variance. Results showed that the TUG was different between normal and AIS subjects, indicating use of TUG as a marker of functional walking performance in AIS is plausible but studies with larger sample size is needed before using TUG to identify AIS with different scoliosis severity. The results also showed that the CoP displacement, velocity and acceleration during a stance phase was different across groups, and with the most prominent deviations found in the moderate IS group. The medial-lateral shifting of the CoP trajectory at mid-foot regions in all IS groups deviated the most. A tendency of asymmetry in CoP progression pattern between feet in IS groups was also found. The deviation of the spine alignment in frontal plane could change the CoP progression patterns during level walking, suggesting the risk of the locomotors subjecting to abnormal loading during daily walking. Education and conservative interventions might be needed for preservation of medical outcome and prevention of back pain and/or musculoskeletal consequences later in the lives of AIS with and without surgical correction.

Adiponectin regulates bone mass in AIS osteopenia via RANKL/OPG and IL6 pathway

BACKGROUND

Osteopenia have been well documented in adolescent idiopathic scoliosis (AIS). Adiponectin has been shown to be inversely proportional to body mass index and to affect bone metabolism. However, the circulating levels of adiponectin and the relationship between adiponectin and low bone mass in AIS remain unclear.

METHODS

A total of 563 AIS and 281 age-matched controls were recruited for this study. Anthropometry and bone mass were measured in all participants. Plasma adiponectin levels were determined by enzyme-linked immunosorbent assay (ELISA) in the AIS and control groups. An improved multiplex ligation detection reaction was performed to study on single nucleotide polymorphism. Facet joints were collected and used to measure the microstructure, the expression of RANKL, OPG, osteoblast-related genes, inflammatory factors, adiponectin and its receptors by qPCR, western blotting and immunohistochemistry. Furthermore, primary cells were extracted from facet joints to observe the reaction after adiponectin stimulation.

RESULTS

Compared with the controls, lower body mass index and a marked increase in circulating adiponectin were observed in AIS osteopenia (17.09 ± 1.09 kg/m² and 21.63 ± 10.30 mg/L). A significant difference in the presence of rs7639352
was detected in the AIS osteopenia, AIS normal bone mass and control groups. The T allele showed a significant higher proportion in AIS osteopenia than AIS normal bone mass and control groups (41.75% vs 31.3% vs 25.7%, p < 0.05). micro-CT demonstrated that the AIS convex side had a significant lower bone volume than concave side. RNA and protein analyses showed that in cancellous bone, higher RANKL/OPG and adipoR1 levels and lower runx2 levels were observed, and in cartilage, higher adipoR1 and IL6 levels were observed in AIS. Furthermore, convex side had higher RANKL/OPG, IL6 and adipoR1 than concave side. Compared with normal primary cells, convex side primary cells showed the most acute action, and concave side primary cells showed the second-most acute action when exposed under same adiponectin concentration gradient.

CONCLUSION

Our results indicated that high circulating adiponectin levels may result from gene variations in AIS osteopenia. Adiponectin has a negative effect on bone metabolism, and this negative effect might be mediated by the ADR1-RANKL/OPG and ADR1-IL6 pathways.

The Role of Vitamin D in the Pathogenesis of Adolescent Idiopathic Scoliosis

Several theories have been proposed to explain the etiology of adolescent idiopathic scoliosis (AIS) until present. However, limited data are available regarding the impact of vitamin D insufficiency or deficiency on scoliosis. Previous studies have shown that vitamin D deficiency and insufficiency are prevalent in adolescents, including AIS patients. A series of studies conducted in Hong Kong have shown that as many as 30% of these patients have osteopenia. The 25-hydroxyvitamin D3 level has been found to positively correlate with bone mineral density (BMD) in healthy adolescents and negatively with Cobb angle in AIS patients; therefore, vitamin D deficiency is believed to play a role in AIS pathogenesis. This study attempts to review the relevant literature on AIS etiology to examine the association of vitamin D and various current theories. Our review suggested that vitamin D deficiency is associated with several current etiological theories of AIS. We postulate that vitamin D deficiency and/or insufficiency affects AIS development by its effect on the regulation of fibrosis, postural control, and BMD. Subclinical deficiency of vitamin K2, a fat-soluble vitamin, is also prevalent in adolescents; therefore, it is possible that the high prevalence of vitamin D deficiency is related to decreased fat intake. Further studies are required to elucidate the possible role of vitamin D in the pathogenesis and clinical management of AIS.

Does postural stability differ between adolescents with idiopathic scoliosis and typically developed? A systematic literature review and meta-analysis

BACKGROUND

Postural stability deficits have been proposed to influence the onset and progression of adolescent idiopathic scoliosis (AIS). This study aimed to systematically identify, critically evaluate and meta-analyse studies assessing postural stability during unperturbed stance with posturography in AIS compared to typically developed adolescents.

METHODS

Studies from four electronic databases (PubMed, Scopus, CINAHL, PEDro) were searched and case-control methodological quality assessed using a risk-of-bias assessment tool and a posturography methodological quality checklist. Pooled data regarding centre of pressure (COP) parameters such as sway area, Mediolateral (ML) and Anteroposterior (AP) position and range were compared for AIS and typically developed adolescents using Cohen's d effect size (ES) and homogeneity estimates.

RESULTS

Eighteen studies for quality analysis and 9 of these for meta-analysis were identified from 971 records. Risk-of-bias assessment identified 6 high, 10 moderate and 2 low risk-of-bias studies. The posturography methodological quality checklist identified 4 low, 7 moderate and 7 high-quality studies. Meta-analysis was performed for sway area whereas ML and AP are presented in three different meta-analyses due to divergent measurement units used in the studies: ML position 1 (MLP1), ML position 2 (MLP2) and ML range (MLR); AP position 1 (APP1), AP position 2 (APP2) and AP range (APR). Cohen's d showed a medium ES difference in sway area 0.65, 95% CI (0.49-0.63), whereas ML showed no (MLP1, MLP2) and large (MLR) ES differences; MLP1 0.15, 95% CI (0.08-0.22); MLP2 0.14, 95% CI (0.08-0.19); and MLR 0.94, 95% CI (0.83-1.04). Cohen's d for AP showed small ES (APP1) and large ES difference (APP2 and APR); APP1 0.43, 95% CI (0.31-0.54); APP2 0.85, 95% CI (0.72-0.97); and APR 0.98, 95% CI (0.87-1.09). Cochran's Q and Higgins I2 showed homogeneity between studies.

CONCLUSIONS

There is moderate quality evidence for decreased postural stability in AIS measured as COP parameters sway area, ML and AP range with a positional shift posteriorly in the sagittal plane. The findings support studying postural stability in early stage AIS and also prospectively identify cause and effect of the curvature as well as effectiveness of postural control interventions in the prevention of scoliosis progression.

Asymmetrical intrapleural pressure distribution: a cause for scoliosis? A computational analysis

PURPOSE

The mechanical link between the pleural physiology and the development of scoliosis is still unresolved. The intrapleural pressure (IPP) which is distributed across the inner chest wall has yet been widely neglected in etiology debates. With this study, we attempted to investigate the mechanical influence of the IPP distribution on the shape of the spinal curvature.

METHODS

A finite element model of pleura, chest and spine was created based on CT data of a patient with no visual deformities. Different IPP distributions at a static end of expiration condition were investigated, such as the influence of an asymmetry in the IPP distribution between the left and right hemithorax. The results were then compared to clinical data.

RESULTS

The application of the IPP resulted in a compressive force of 22.3 N and a flexion moment of 2.8 N m at S1. An asymmetrical pressure between the left and right hemithorax resulted in lateral deviation of the spine towards the side of the reduced negative pressure. In particular, the pressure within the dorsal section of the rib cage had a strong influence on the vertebral rotation, while the pressure in medial and ventral region affected the lateral displacement.

CONCLUSIONS

An asymmetrical IPP caused spinal deformation patterns which were comparable to deformation patterns seen in scoliotic spines. The calculated reaction forces suggest that the IPP contributes in counterbalancing the weight of the intrathoracic organs. The study confirms the potential relevance of the IPP for spinal biomechanics and pathologies, such as adolescent idiopathic scoliosis.

THE ETIOLOGIC RELEVANCE OF 3-D PATHOANATOMY OF ADOLESCENT IDIOPATHIC SCOLIOSIS

ABSTRACT Despite many years of dedicated research into the etiopathogenesis of adolescent idiopathic scoliosis, there is still no single distinct cause for this puzzling condition. In this overview, we attempt to link knowledge on the complex three-dimensional pathoanatomy of AIS, based on our ongoing research in this field, with etiopathogenic questions. Evidence from multiple recent cross-sectional imaging studies is provided that supports the hypothesis that AIS has an intrinsic biomechanical basis: an imbalance between the biomechanical loading of the upright human spine due to its unique sagittal configuration on the one hand, and the body’s compensating mechanisms on the other. The question that remains in the etiology of AIS, and the focus of our ongoing research, is to determine what causes or induces this imbalance.

Restrained Differential Growth: The Initiating Event of Adolescent Idiopathic Scoliosis?

STUDY DESIGN

An experimental model study and a short review of literature.

OBJECTIVE

The purpose of this study was to explore a new hypothesis suggesting that the curvatures seen in adolescent idiopathic scoliosis (AIS) originate from restrained differential growth between the vertebral column and the surrounding musculo-ligamentary structures.

SUMMARY OF BACKGROUND DATA

Despite decades of research, there is no generally accepted theory on the physical origin of the severe spinal deformations seen in AIS. The prevailing theories tend to focus on left-right asymmetry, rotational instability, or the sagittal spinal profile in idiopathic scoliosis.

METHODS

We test our hypothesis with a physical model of the spine that simulates growth, counteracted by ligaments and muscles, modeled by tethers and springs. Growth of the spine is further restrained by an anterior band representing the thorax, the linea alba, and abdominal musculature. We also explore literature in search of molecular mechanisms that may induce differential growth.

RESULTS

Differential growth in the restrained spine model first induces hypokyphosis and mild lateral bending of the thoracic spine, but then suddenly escalates into a scoliotic deformity, consistent with clinical observations of AIS. The band simulating the ventral structures of the body had a pivotal effect on sagittal curvature and the initiation of lateral bending and rotation. In literature, several molecular mechanisms were found that may explain the occurrence of differential growth between the spine and the musculo-ligamentary structures.

CONCLUSION

While AIS is a three-dimensional deformation of the spine, it appears that restrained differential growth in the sagittal plane can result in lateral bending and rotation without a pre-existing left-right asymmetry. This supports the concept that AIS may result from a growth imbalance rather than a local anatomical defect.

LEVEL OF EVIDENCE

N/A.

Anatomical and radiological characteristics in adolescent idiopathic scoliosis with surgical indication

OBJECTIVE

This study aims to analyze the anatomical and radiological characteristics of adolescent idiopathic scoliosis patients with surgical indication.

METHODS

Retrospective, descriptive study of 100 medical records pertaining to patients included in the group of scoliosis with surgical indication from the years 2008 to 2015. Descriptive statistics were used for statistical analysis.

RESULTS

28 patients met the inclusion and exclusion criteria, and were selected for the study. The average age was 15.4 (SD ± 1.2 years); in the selected sample, the female/male ratio was 6:1; the kyphosis measured in degrees by Cobb angle between T5-T12 had an average 32.10 (SD ± 13.37); according to the Lenke classification, the most prevalent type was type 2, representing 28.6% of cases.

CONCLUSION

The mean patient age in the present study was 15.4 (SD ± 1.2 years); the most prevalent type was type 2 in the Lenke classification. There is a need for new anatomical and radiological studies to elucidate the morphological characteristics common in adolescent idiopathic scoliosis patients.

Upright, prone, and supine spinal morphology and alignment in adolescent idiopathic scoliosis

BACKGROUND

Patients with adolescent idiopathic scoliosis (AIS) are usually investigated by serial imaging studies during the course of treatment, some imaging involves ionizing radiation, and the radiation doses are cumulative. Few studies have addressed the correlation of spinal deformity captured by these different imaging modalities, for which patient positioning are different. To the best of our knowledge, this is the first study to compare the coronal, axial, and sagittal morphology of the scoliotic spine in three different body positions (upright, prone, and supine) and between three different imaging modalities (X-ray, CT, and MRI).

METHODS

Sixty-two AIS patients scheduled for scoliosis surgery, and having undergone standard pre-operative work-up, were included. This work-up included upright full-spine radiographs, supine bending radiographs, supine MRI, and prone CT as is the routine in one of our institutions. In all three positions, Cobb angles, thoracic kyphosis (TK), lumbar lordosis (LL), and vertebral rotation were determined. The relationship among three positions (upright X-ray, prone CT, and supine MRI) was investigated according to the Bland-Altman test, whereas the correlation was described by the intraclass correlation coefficient (ICC).

RESULTS

Thoracic and lumbar Cobb angles correlated significantly between conventional radiographs (68° ± 15° and 44° ± 17°), prone CT (54° ± 15° and 33° ± 15°), and supine MRI (57° ± 14° and 35° ± 16°; ICC ≥0.96; P < 0.001). The thoracic and lumbar apical vertebral rotation showed a good correlation among three positions (upright, 22° ± 12° and 11° ± 13°; prone, 20° ± 9° and 8° ± 11°; supine, 16° ± 11° and 6° ± 14°; ICC ≥0.82; P < 0.001). The TK and LL correlated well among three different positions (TK 26° ± 11°, 22° ± 12°, and 17° ± 10°; P ≤ 0.004; LL 49° ± 12°, 45° ± 11°, and 44° ± 12°; P < 0.006; ICC 0.87 and 0.85).

CONCLUSIONS

Although there is a generalized underestimation of morphological parameters of the scoliotic deformity in the supine and prone positions as compared to the upright position, a significant correlation of these parameters is still evident among different body positions by different imaging modalities. Findings of this study suggest that severity of scoliotic deformity in AIS patients can be largely represented by different imaging modalities despite the difference in body positioning.

Schroth Physiotherapeutic Scoliosis-Specific Exercises Added to the Standard of Care Lead to Better Cobb Angle Outcomes in Adolescents with Idiopathic Scoliosis - an Assessor and Statistician Blinded Randomized Controlled Trial

Background

The North American non-surgical standard of care for adolescent idiopathic scoliosis (AIS) includes observation and bracing, but not exercises. Schroth physiotherapeutic scoliosis-specific exercises (PSSE) showed promise in several studies of suboptimal methodology. The Scoliosis Research Society calls for rigorous studies supporting the role of exercises before including it as a treatment recommendation for scoliosis.

Objectives

To determine the effect of a six-month Schroth PSSE intervention added to standard of care (Experimental group) on the Cobb angle compared to standard of care alone (Control group) in patients with AIS.

Methods

Fifty patients with AIS aged 10–18 years, with curves of 10°-45° and Risser grade 0–5 were recruited from a single pediatric scoliosis clinic and randomized to the Experimental or Control group. Outcomes included the change in the Cobb angles of the Largest Curve and Sum of Curves from baseline to six months. The intervention consisted of a 30–45 minute daily home program and weekly supervised sessions. Intention-to-treat and per protocol linear mixed effects model analyses are reported.

Results

In the intention-to-treat analysis, after six months, the Schroth group had significantly smaller Largest Curve than controls (-3.5°, 95% CI -1.1° to -5.9°, p = 0.006). Likewise, the between-group difference in the square root of the Sum of Curves was -0.40°, (95% CI -0.03° to -0.8°, p = 0.046), suggesting that an average patient with 51.2° at baseline, will have a 49.3° Sum of Curves at six months in the Schroth group, and 55.1° in the control group with the difference between groups increasing with severity. Per protocol analyses produced similar, but larger differences: Largest Curve = -4.1° (95% CI -1.7° to -6.5°, p = 0.002) and Sum of Curves=−0.5° (95% CI -0.8 to 0.2, p = 0.006).

Conclusion

Schroth PSSE added to the standard of care were superior compared to standard of care alone for reducing the curve severity in patients with AIS.

Trial Registration

NCT01610908

The Spinopelvic Geometry in Different Lenke Curve Types of Adolescent Idiopathic Scoliosis

BACKGROUND

The Lenke classification is well established in differentiation of curve types in adolescent idiopathic scoliosis (AIS) and guides selection of fusion levels. However, to date, it has neglected the spinopelvic parameters that have been associated with compensatory mechanisms in balancing the human erect posture and adjacent segment problems after spinal fusion. The aim of this study was to investigate spinopelvic parameters in different types of AIS curves.

MATERIAL AND METHODS

Preoperative whole-spine radiographs from 100 patients with AIS were reviewed and the curves were classified according to Lenke. In addition, sagittal spinopelvic parameters (pelvic incidence, sacral slope, pelvic tilt) were measured and compared between different curve types and to normal population values.

RESULTS

The spinopelvic balance was not statistically distinguishable in different Lenke curve types. Slight differences of the spinopelvic balance, compared with normal population values, were found in AIS Lenke Type 5 and 6 curves (major curve at the lumbar/thoracolumbar region) with a pelvic incidence of 44° ± 8° (norm 49°), sacral slope of 34° ± 7° (norm 41°), and pelvic tilt of 10° ± 7° (norm 8°).

CONCLUSION

Overall, the variances of spinopelvic parameters in different AIS curve types do not seem statistically large enough for a potential clinical relevance. However, the sacrum is more verticalized in AIS curves with major curves located in the lumbar/thoracolumbar region. It remains to be investigated whether such a verticalized sacrum might be a compensatory mechanism to keep the whole spine balanced and if it reverses with correction of the scoliosis.

Body composition in males with adolescent idiopathic scoliosis: a case-control study with dual-energy X-ray absorptiometry

Background

In contrast to the well-characterized body growth and development of females with adolescent idiopathic scoliosis (AIS), the pubertal growth pattern of male patients has not been well-documented. Recently, significantly lower body weight (BW) and body mass index (BMI) were reported in males with AIS, and were thought to be related to curve progression. A case–control study was carried out to characterize the body composition and bone status of males with AIS, with the aim of gaining a better understanding of lower BW among these patients.

Methods

Forty-seven males with AIS and forty age- and gender-matched healthy controls were recruited. Standing height (SH) and BW were measured. The SH of the males who had AIS was corrected using Bjure’s equation, and then the BMI was calculated. Body composition, including subcranial fat mass (FM), lean mass (LM), and bone mineral content (BMC), and bone mineral density (BMD) were analyzed using dual-energy X-ray absorptiometry. The LM index (LMi) and the FM index (FMi) were calculated by dividing the FM and LM by the square of the SH. Logistic regression analysis was employed for comparison between AIS and controls.

Results

The AIS patients had comparable age and Tanner staging for pubic hair as the controls. After adjustment for age, the AIS patients showed comparable SH but significantly lower BW and BMI than that of the controls. The LM, LMi, BMC and BMD were also significantly lower in the AIS patients than in the controls. However, the difference in BMC between two groups was not significant by adjusting for age, FM and LM.

Conclusion

The male AIS patients showed abnormal body composition, presenting as significantly lower LM than the controls. The lower BMC observed in the patients might due to the abnormal body composition.

Quantifying spinal gait kinematics using an enhanced optical motion capture approach in adolescent idiopathic scoliosis

BACKGROUND AND PURPOSE

The pathogenesis of adolescent idiopathic scoliosis (AIS) remains poorly understood. Previous research has indicated possible relationships between kinematics of the spine, pelvis and lower extremities during gait and the progression of AIS, but adequate evidence on spinal kinematics is lacking. The aim of this study was to provide a detailed assessment of spinal gait kinematics in AIS patients compared to asymptomatic controls.

METHODS

Fourteen AIS patients and 15 asymptomatic controls were included. Through introducing a previously validated enhanced trunk marker set, sagittal and frontal spinal curvature angles as well as general trunk kinematics were measured during gait using a 12-camera Vicon motion capture system. Group comparisons were conducted using T-tests and relationships between kinematic parameters and severity of scoliosis (Cobb angle) were investigated using regression analyses.

RESULTS

The sagittal thoracic curvature angle in AIS patients showed on average 10.7° (4.2°, 17.3°) less kyphosis but 4.9° (2.3°, 7.6°) more range of motion (Cobb angle-dependent (R(2)=0.503)). In the frontal plane, thoracic and thoracolumbar/lumbar curvature angles indicated average lateral deviations in AIS patients. General trunk kinematics and spatio-temporal gait parameters, however, did not show any clinically relevant differences between the groups.

CONCLUSIONS

This demonstrates that the dynamic functionality of the scoliotic spine can be assessed using advanced non-invasive optical approaches and that these should become standard in clinical gait analysis. Furthermore, curvature angle data might be used to drive sophisticated computer simulation models in order to gain an insight into the dynamic loading behavior of the scoliotic spine during gait.

Lateral Semicircular Canal Asymmetry in Idiopathic Scoliosis: An Early Link between Biomechanical, Hormonal and Neurosensory Theories?

INTRODUCTION

Despite its high incidence and severe morbidity, the physiopathogenesis of adolescent idiopathic scoliosis (AIS) is still unknown. Here, we looked for early anomalies in AIS which are likely to be the cause of spinal deformity and could also be targeted by early treatments. We focused on the vestibular system, which is suspected of acting in AIS pathogenesis and which exhibits an end organ with size and shape fixed before birth. We hypothesize that, in adolescents with idiopathic scoliosis, vestibular morphological anomalies were already present at birth and could possibly have caused other abnormalities.

MATERIALS AND METHODS

The vestibular organ of 18 adolescents with AIS and 9 controls were evaluated with MRI in a prospective case controlled study. We studied lateral semicircular canal orientation and the three semicircular canal positions relative to the midline. Lateral semicircular canal function was also evaluated by vestibulonystagmography after bithermal caloric stimulation.

RESULTS

The left lateral semicircular canal was more vertical and further from the midline in AIS (p = 0.01) and these two parameters were highly correlated (r = -0.6; p = 0.02). These morphological anomalies were associated with functional anomalies in AIS (lower excitability, higher canal paresis), but were not significantly different from controls (p>0.05).

CONCLUSION

Adolescents with idiopathic scoliosis exhibit morphological vestibular asymmetry, probably determined well before birth. Since the vestibular system influences the vestibulospinal pathway, the hypothalamus, and the cerebellum, this indicates that the vestibular system is a possible cause of later morphological, hormonal and neurosensory anomalies observed in AIS. Moreover, the simple lateral SCC MRI measurement demonstrated here could be used for early detection of AIS, selection of children for close follow-up, and initiation of preventive treatment before spinal deformity occurs.