A computed tomography-based spatial reference for pedicle screw placement in adolescent idiopathic scoliosis.

STUDY DESIGN: Cross-sectional. OBJECTIVES: To determine semiautomatically the 3D position of the pedicle axis in operative adolescent idiopathic scoliosis (AIS) patients relative to the operating table and the lamina, as orientation for pedicle screw placement for better understanding and reference of spine surgeons. Pedicle morphology is well described as the angle between the convex and concave pedicle. However, the pedicle angle as relative to the neutral anterior-posterior axis or to an easy-to-use intravertebral landmark, remained unknown. METHODS: The pedicles of the apex and two adjacent vertebrae cranial and caudal to the apex of 86 right-sided primary thoracic AIS curves were evaluated using semiautomatic 3D software on high-resolution CT scans, in the same prone position as during surgery. Pedicle vectors were obtained and calculated as transverse and sagittal angles, as relative to the neutral axis (corresponding with an axis perpendicular to the operating table) and to an axis perpendicular to the lamina. RESULTS: At the apex, the mean convex and concave transverse pedicle angles were 14.3º (95% confidence interval [95% CI]: 12.0-16.6) and 30.4º (95% CI: 28.1-32.8) to the right. The angles decreased toward the adjacent levels cranial and caudal to the apex (p < 0.001) and linearly increased with a higher Cobb angle (r ≥ 0.472; p < 0.001). The mean transverse pedicle-lamina angles, sagittal pedicle angles and the sagittal pedicle-lamina angles differed along the curve as well (p < 0.001). CONCLUSIONS: Pedicle angulation differs between convex and concave and depends on the position of the vertebra relative to the apex, as well as the curve severity. The transverse and sagittal pedicle angles, as relative to the operating table and laminae, could provide useful reference for better understanding of the distorted 3D morphology, and the angles, as given in this study, could serve as an approximate guideline for the expected direction of the pedicle screw. LEVEL OF EVIDENCE: Level IV.

Bone measurements at multiple skeletal sites in adolescent idiopathic scoliosis-an in vivo correlation study using DXA, HR-pQCT and QCT.

Significant correlations for bone mineral density and bone microstructure between spinal and non-spinal skeletal sites (distal radius and proximal femur) in adolescent idiopathic scoliosis (AIS) patients were observed, indicating that proximal femoral DXA and distal radial HR-pQCT could provide valid clinical assessments in patients with AIS. PURPOSE: Low bone mass is an important feature of adolescent idiopathic scoliosis (AIS), which is a complex 3D spinal deformity that affects girls during puberty. However, no clinical imaging modality is suitable for regular monitoring on their spinal bone qualities in rapid growth period. Therefore, we investigated whether bone mineral density (BMD) and bone microstructure at non-spinal sites correlated with BMD and mechanical property in the spine in AIS patients. METHODS: Thirty-two AIS girls (16.7 ± 3.5 years old with mean Cobb angle of 67 ± 11°) who underwent pre-operative spine CT examination for navigation surgery were recruited. Volumetric BMD (vBMD) of lumbar spine (LS) was measured by quantitative computed tomography (QCT), vBMD and bone microstructure of distal radius (DR) by high-resolution peripheral QCT (HR-pQCT) and areal BMDs of total hip (TH) and femoral necks (FN) by dual-energy X-ray absorptiometry (DXA). Biomechanical properties of the DR and LS were estimated by finite element analysis (FEA). Pearson correlation was performed to study the correlation between bone parameters at these three sites. RESULTS: LS vBMD correlated significantly with both FN and TH aBMD (R = 0.663-0.725, both p < 0.01) and with DR microstructural parameters (R = 0.380-0.576, all p < 0.05). Mechanical properties of LS and DR were also correlated (R = 0.398, p = 0.039). CONCLUSIONS: Bone measurement at proximal femur and distal radius could provide an additional predictive power in estimating the bone changes at spine, which is the primary site of deformity in AIS patients. Our result indicated that DXA and HR-pQCT could provide a valid surrogate for spine bone measurements in AIS patients.

Aberrant miR-145-5p/ß-catenin signal impairs osteocyte function in adolescent idiopathic scoliosis.

Recently, noncoding RNAs have been thought to play important roles in the sporadic occurrence of spinal deformity of adolescent idiopathic scoliosis (AIS). As a prognostic factor for curve progression, low bone mass has been hypothesized to crosstalk with AIS pathogenesis. Abnormal osteoblasts activities are reported in AIS without a clear mechanism. In this study, bone biopsies from patients with AIS and control subjects and the primary osteoblasts derived from those samples were used to identify the potential microRNA (miRNA) candidates that interfere with osteoblasts and osteocytes function. Microarray analysis identified miRNA-145-5p (miR-145) as a potential upstream regulator. miR-145 and ß-catenin mRNA ( CTNNB1) were overexpressed in AIS bone tissues and primary osteoblasts, and their expression correlated positively in AIS. Knockdown of miR-145 restored impaired osteocyte activity through the down-regulation of active ß-catenin expression and its transcriptional activity. Significant negative correlations between circulating miR-145 and serum sclerostin, osteopontin, and osteoprotegerin were noted in patients with AIS, which was in line with our cellular findings. This is the first study to demonstrate the effect of aberrant miRNA expression and its effect on osteocyte function in AIS, which may contribute to the low bone mass. Our findings also provide insight into the development of circulating microRNAs as a bone quality biomarker or even a prognostic biomarker for AIS.-Zhang, J., Chen, H., Leung, R. K. K., Choy, K. W., Lam, T. P., Ng, B. K. W., Qiu,Y., Feng, J. Q., Cheng, J. C. Y., Lee, W. Y. W. Aberrant miR-145-5p/ß-catenin signal impairs osteocyte function in adolescent idiopathic scoliosis.

Thumb Ossification Composite Index (TOCI) for Predicting Peripubertal Skeletal Maturity and Peak Height Velocity in Idiopathic Scoliosis: A Validation Study of Premenarchal Girls with Adolescent Idiopathic Scoliosis Followed Longitudinally Until Skeletal Maturity.

BACKGROUND: Accurate skeletal maturity assessment is important to guide clinical evaluation of idiopathic scoliosis, but commonly used methods are inadequate or too complex for rapid clinical use. The objective of the study was to propose a new simplified staging method, called the thumb ossification composite index (TOCI), based on the ossification pattern of the 2 thumb epiphyses and the adductor sesamoid bone; to determine its accuracy in predicting skeletal maturation when compared with the Sanders simplified skeletal maturity system (SSMS); and to validate its interrater and intrarater reliability. METHODS: Hand radiographs of 125 girls, acquired when they were newly diagnosed with idiopathic scoliosis prior to menarche and during longitudinal follow-up until skeletal maturity (a minimum of 4 years), were scored with the TOCI and SSMS. These scores were compared with digital skeletal age (DSA) and radius, ulna, and small hand bones (RUS) scores; anthropometric data; peak height velocity; and growth-remaining profiles. Correlations were analyzed with the chi-square test, Spearman and Cramer V correlation methods, and receiver operating characteristic curve analysis. Reliability analysis using the intraclass correlation (ICC) was conducted. RESULTS: Six hundred and forty-five hand radiographs (average, 5 of each girl) were scored. The TOCI staging system was highly correlated with the DSA and RUS scores (r = 0.93 and 0.92, p < 0.01). The mean peak height velocity (and standard deviation) was 7.43 ± 1.45 cm/yr and occurred at a mean age of 11.9 ± 0.86 years, with 70.1% and 51.4% of the subjects attaining their peak height velocity at TOCI stage 5 and SSMS stage 3, respectively. The 2 systems predicted peak height velocity with comparable accuracy, with a strong Cramer V association (0.526 and 0.466, respectively; p < 0.01) and similar sensitivity and specificity on receiver operating characteristic curve analysis. The mean age at menarche was 12.57 ± 1.12 years, with menarche occurring over several stages in both the TOCI and the SSMS. The growth remaining predicted by TOCI stage 8 matched well with that predicted by SSMS stage 7, with a mean of <2 cm/yr of growth potential over a mean of <1.7 years at these stages. The TOCI also demonstrated excellent reliability, with an overall ICC of >0.97. CONCLUSIONS: The new proposed TOCI could provide a simplified staging system for the assessment of skeletal maturity of subjects with idiopathic scoliosis. The index needs to be subjected to further multicenter validation in different ethnic groups.

Unique local bone tissue characteristics in iliac crest bone biopsy from adolescent idiopathic scoliosis with severe spinal deformity.

Adolescent idiopathic scoliosis is a complex disease with unclear etiopathogenesis. Systemic and persistent low bone mineral density is an independent prognostic factor for curve progression. The fundamental question of how bone quality is affected in AIS remains controversy because there is lack of site-matched control for detailed analysis on bone-related parameters. In this case-control study, trabecular bone biopsies from iliac crest were collected intra-operatively from 28 severe AIS patients and 10 matched controls with similar skeletal and sexual maturity, anthropometry and femoral neck BMD Z-score to control confounding effects. In addition to static histomorphometry, micro-computed tomography (µCT) and real time-PCR (qPCR) analyses, individual trabecula segmentation (ITS)-based analysis, finite element analysis (FEA), energy dispersive X-ray spectroscopy (EDX) were conducted to provide advanced analysis of structural, mechanical and mineralization features. µCT and histomorphometry showed consistently reduced trabecular number and connectivity. ITS revealed predominant change in trabecular rods, and EDX confirmed less mineralization. The structural and mineralization abnormality led to slight reduction in apparent modulus, which could be attributed to differential down-regulation of Runx2, and up-regulation of Spp1 and TRAP. In conclusion, this is the first comprehensive study providing direct evidence of undefined unique pathological changes at different bone hierarchical levels in AIS.

Radiation dose of digital radiography (DR) versus micro-dose x-ray (EOS) on patients with adolescent idiopathic scoliosis: 2016 SOSORT- IRSSD "John Sevastic Award" Winner in Imaging Research.

BACKGROUND: Patients with adolescent idiopathic scoliosis (AIS) frequently receive x-ray imaging at diagnosis and subsequent follow monitoring. The ionizing radiation exposure has accumulated through their development stage and the effect of radiation to this young vulnerable group of patients is uncertain. To achieve the ALARA (as low as reasonably achievable) concept of radiation dose in medical imaging, a slot-scanning x-ray technique by the EOS system has been adopted and the radiation dose using micro-dose protocol was compared with the standard digital radiography on patients with AIS. METHODS: Ninety-nine participants with AIS underwent micro-dose EOS and 33 underwent standard digital radiography (DR) for imaging of the whole spine. Entrance-skin dose was measured using thermoluminescent dosimeters (TLD) at three regions (i.e. dorsal sites at the level of sternal notch, nipple line, symphysis pubis). Effective dose and organ dose were calculated by simulation using PCXMC 2.0. Data from two x-ray systems were compared using independent-samples t-test and significance level at 0.05. All TLD measurements were conducted on PA projection only. Image quality was also assessed by two raters using Cobb angle measurement and a set of imaging parameters for optimization purposes. RESULTS: Entrance-skin dose from micro-dose EOS system was 5.9-27.0 times lower at various regions compared with standard DR. The calculated effective dose was 2.6 ± 0.5 (µSv) and 67.5 ± 23.3 (µSv) from micro-dose and standard DR, respectively. The reduction in the micro-dose was approximately 26 times. Organ doses at thyroid, lung and gonad regions were significantly lower in micro-dose (p < 0.001). Data were further compared within the different gender groups. Females received significantly higher (p < 0.001) organ dose at ovaries compared to the testes in males. Patients with AIS received approximately 16-34 times lesser organ dose from micro-dose x-ray as compared with the standard DR. There was no significant difference in overall rating of imaging quality between EOS and DR. Micro-dose protocol provided enough quality to perform consistent measurement on Cobb angle. CONCLUSIONS: Entrance-skin dose, effective dose and organ dose were significantly reduced in micro-dose x-ray. The effective dose of a single micro-dose x-ray (2.6 µSv) was less than a day of background radiation. As AIS patients require periodic x-ray follow up for surveillance of curve progression, clinical use of micro-dose x-ray system is beneficial for these young patients to reduce the intake of ionizing radiation.

Curve Progression in Adolescent Idiopathic Scoliosis With a Minimum of 2 Years' Follow-up After Completed Brace Weaning With Reference to the SRS Standardized Criteria.

STUDY DESIGN: A retrospective study. OBJECTIVES: To investigate curve evolution after brace weaning in adolescent idiopathic scoliosis (AIS) with reference to the Scoliosis Research Society (SRS) criteria. SUMMARY OF BACKGROUND DATA: Previous studies mainly focused on curve evolution during bracing in AIS. However, curve progression after brace weaning was not well addressed. METHODS: Braced AIS girls followed up for at least 2 years after brace weaning were reviewed. All patients had radiographs at initial visit, brace weaning, 6 months, 1 year, and 2 years after brace weaning, and last follow-up. Curve progression after brace weaning was separately defined as increase in Cobb angle >5 degrees and curve magnitude >45 degrees. The predictors for curve progression were identified using the independent t test. RESULTS: 200 AIS girls were reviewed. The average duration of follow-up after brace weaning was 51.4 ± 25.6 months. Compared with brace weaning, at 6 months, 1 year, 2 years and last follow-up after brace weaning, 50 (25.0%), 60 (30.0%), 93 (46.5%), and 87 (43.5%) patients, respectively, had curve progression >5 degrees; 0 (0%), 0 (0%), 2 (1%), and 2 (1%) patients, respectively, had surgery recommended; among those with Cobb angle ≤40 degrees at brace weaning, 7 (4.0%), 11 (6.3%), 16 (9.2%), and 18 (10.3%) patients, respectively, had Cobb angle >45 degrees; the mean progression magnitudes were 2.6 ± 5.8, 3.5 ± 5.8, 5.1 ± 6.5, and 5.4 ± 7.4 degrees, respectively; and the mean progression rates were 0.34 ± 0.83, 0.16 ± 0.56, 0.13 ± 0.39, and 0.006 ± 0.28 degrees/month, respectively. Cobb angle at brace weaning was associated with increase in Cobb angle >5 degrees (p = .033) and curve magnitude >45 degrees (p < .001) after brace weaning. CONCLUSIONS: Curve progression after brace weaning is observed in 43.5% AIS patients. The highest risk occurs within 6 months after brace weaning whereas Cobb angle remains stable after 2 years' follow-up. High Cobb angle at brace weaning indicates high risk of curve progression after brace weaning. LEVEL OF EVIDENCE: Level III.

Anterior Overgrowth in Primary Curves, Compensatory Curves and Junctional Segments in Adolescent Idiopathic Scoliosis.

INTRODUCTION: Although much attention has been given to the global three-dimensional aspect of adolescent idiopathic scoliosis (AIS), the accurate three-dimensional morphology of the primary and compensatory curves, as well as the intervening junctional segments, in the scoliotic spine has not been described before. METHODS: A unique series of 77 AIS patients with high-resolution CT scans of the spine, acquired for surgical planning purposes, were included and compared to 22 healthy controls. Non-idiopathic curves were excluded. Endplate segmentation and local longitudinal axis in endplate plane enabled semi-automatic geometric analysis of the complete three-dimensional morphology of the spine, taking inter-vertebral rotation, intra-vertebral torsion and coronal and sagittal tilt into account. Intraclass correlation coefficients for interobserver reliability were 0.98-1.00. Coronal deviation, axial rotation and the exact length discrepancies in the reconstructed sagittal plane, as defined per vertebra and disc, were analyzed for each primary and compensatory curve as well as for the junctional segments in-between. RESULTS: The anterior-posterior difference of spinal length, based on "true" anterior and posterior points on endplates, was +3.8% for thoracic and +9.4% for (thoraco)lumbar curves, while the junctional segments were almost straight. This differed significantly from control group thoracic kyphosis (-4.1%; P<0.001) and lumbar lordosis (+7.8%; P<0.001). For all primary as well as compensatory curves, we observed linear correlations between the coronal Cobb angle, axial rotation and the anterior-posterior length difference (r≥0.729 for thoracic curves; r≥0.485 for (thoraco)lumbar curves). CONCLUSIONS: Excess anterior length of the spine in AIS has been described as a generalized growth disturbance, causing relative anterior spinal overgrowth. This study is the first to demonstrate that this anterior overgrowth is not a generalized phenomenon. It is confined to the primary as well as the compensatory curves, the junctional zones do not exhibit this growth discrepancy, however, they are straight.

Halo-gravity traction combined with assisted ventilation: an effective pre-operative management for severe adult scoliosis complicated with respiratory dysfunction.

PURPOSE: To investigate the change of pulmonary function in adult scoliosis patients with respiratory dysfunction undergoing HGT combined with assisted ventilation. METHODS: 21 adult patients were retrospectively reviewed with a mean age of 26.2 years. Inclusion criteria were as follows: age over 18 years old; coronal Cobb angle greater than 100°; with respiratory failure; and duration of HGT more than 1 month. All patients underwent respiratory training. RESULTS: The Cobb angle averaged 131.21° and was reduced to 107.68° after HGT. Significantly increased mean forced vital capacity (FVC) was found after HGT (P = 0.003) with significantly improved percent-predicted values for FVC (P < 0.001). Meanwhile, significantly increased forced expiratory volume in 1 s (FEV1) was also observed (P < 0.001) with significantly improved percent-predicted values for FEV1 (P = 0.003) after HGT. CONCLUSION: The results of our study revealed that combined HGT and assisted ventilation would be beneficial to pulmonary function improvement in severe adult scoliosis cases, most of which were young adults.

Lower Muscle Mass and Body Fat in Adolescent Idiopathic Scoliosis Are Associated With Abnormal Leptin Bioavailability.

STUDY DESIGN: This was a case-control study. OBJECTIVE: This study aimed to investigate the body composition and its correlation with leptin and soluble leptin receptor (sOB-R) levels in girls with adolescent idiopathic scoliosis (AIS) and compared with healthy controls. SUMMARY OF BACKGROUND DATA: Patients with AIS are associated with lower body weight, taller stature, lower body mass index (BMI), and deranged bone quality. Despite the widely reported lower BMI and body weight in girls with AIS, the body composition of these patients was not thoroughly studied with sufficient sample size. Leptin is an important factor in regulating energy and bone metabolism, and has been postulated as one of the etiologic factors of AIS. METHODS: One hundred forty-eight AIS and 116 control girls aged 12 to 14 were recruited. Body composition was measured with bioelectrical impedance analysis. Caloric intake and physical activity level were assessed by food frequency and Baecke questionnaires respectively. Serum total leptin and sOB-R levels were measured with enzyme-linked immunosorbent assay, and free leptin index was calculated. RESULTS: AIS girls had lower body weight and BMI, other anthropometric and sexual maturity parameters were comparable with controls. There were no difference in caloric intake and physical activity levels. After adjustment for physical activity level, AIS girls had lower skeletal muscle mass, lower body fat, and %body fat. Higher sOB-R and lower free leptin index were found in AIS girls after adjusted for age and body weight. Weaker correlations between serum total leptin, FLI, and body composition parameters were observed in AIS girls. CONCLUSION: Results suggested that the lower body weight in AIS girls was contributed by both lower skeletal muscle mass and lower body fat. Altered leptin bioavailability also exists in AIS girls and could lead to lower body weight, lower BMI, and abnormal body composition that were manifested in AIS simultaneously. LEVEL OF EVIDENCE: 4.

Anatomical Origin of Abnormal Somatosensory-Evoked Potential (SEP) in Adolescent Idiopathic Scoliosis With Different Curve Severity and Correlation With Cerebellar Tonsillar Level Determined by MRI.

STUDY DESIGN: A prospective cohort study. OBJECTIVE: The aim of this study was to compare the somatosensory-evoked potential (SEP) findings of adolescent idiopathic scoliosis (AIS) subjects of different curve severity with age- and gender-matched controls and to evaluate any correlation between the site of the SEP abnormality with cerebellar tonsillar level measured by magnetic resonance imaging (MRI). SUMMARY OF BACKGROUND DATA: Our previous studies showed that a higher percentage of SEP abnormality and cerebellar tonsillar ectopia was present in AIS patients than in normal controls. However, the relationship between the anatomical site of the neurophysiological abnormality and the severity in AIS patients has not been defined. METHODS: SEP measurement was conducted on 91 Chinese AIS girls with major right thoracic curve of different curve severity (mild, moderate, severe) and 49 matched normal controls. Waveform characteristics (latency and amplitude) were compared among groups. Specific location of SEP abnormality was identified from tibial to cortical levels. Cerebellar tonsillar ectopia was defined by the previously established reference line between basion and opisthion on MRI. RESULTS: Significant prolonged P37 latency was found on the right side between severe AIS patients and normal controls, while increased inter-side P37 latency difference was found between severe versus moderate, and severe versus normal controls. Cerebellar tonsillar ectopia was detected in 27.3% of severe group, 5.8% to 6.7% in mild and moderate group, but none in normal controls. Abnormal SEP occurred superior to C5 region in all surgical (severe) patients, of whom 58% had cerebellar tonsillar ectopia. CONCLUSION: AIS patients showed significant prolonged latency and increased latency difference on the side of major curvature. The incidence of SEP abnormality increased with curve severity and occurred above the C5 level. The findings suggested that there was a subgroup of progressive AIS with subclinical neurophysiological dysfunction, associated with underlying neuromorphological abnormalities, which were only detectable by SEP and MRI. LEVEL OF EVIDENCE: 3.

Use of Tranexamic Acid (TXA) on reducing blood loss during scoliosis surgery in Chinese adolescents.

BACKGROUND: Many reports had been received on the application of antifibrinolytic medications on spinal corrective surgery and the surgical outcome evaluations of its efficacy on reducing blood loss. This study aimed to assess the efficacy of tranexamic acid (TXA) in reducing operative blood loss during posterior spinal fusion for the treatment of severe adolescent idiopathic scoliosis (AIS). METHODS: A retrospective cohort study was carried out on 90 (TXA = 55, Control = 35) AIS girls undergoing posterior spinal surgery. Patients in TXA group used TXA as an antifibrinolytic agent to reduce blood loss, while control group did not. Blood loss, haemoglobin change and amount of blood transfused was estimated from intraoperative measurement by anaesthesiologists. Demographics were compared using Student's T-test or Chi-square test where appropriate. Linear regression modelling was carried out between the use of TXA and total blood loss with controlling of confounding factors. RESULTS: Mean age and mean maximum major curve were 15.2 and 73°, and 15.3 and 63° in TXA and control groups respectively. TXA group showed significantly less intra-operative blood loss than the control group from intraoperative measurement (1.8 L vs. 3.9 L, p < 0.01) and volume of cell saver blood transfused back to patients (0.6 L vs. 1.7 L, p < 0.01). TXA group also showed significantly shorter total time taken for surgery (437 min vs. 502 min, p < 0.01), and total blood loss per surgical segment level (0.1 L vs. 0.3 L, p < 0.01). Regression models showed that the use of TXA decreased total blood loss by 794.3 ml after adjusting for maximum major curve, age, number of segments fused, bone graft, clotting capability, and infusion of coagulation factors. CONCLUSIONS: Patients undergoing posterior spinal corrective surgery with the use of TXA showed much reduced total blood loss, reduced use of transfused blood, much less cell saver blood transfused back to the patient. The total blood loss was decreased by after using TXA after controlling for maximum major curve, age, surgical parameters, clotting capability, and infusion of coagulation factors.

MRI-based morphological evidence of spinal cord tethering predicts curve progression in adolescent idiopathic scoliosis.

BACKGROUND CONTEXT: Existing prognostic factors for adolescent idiopathic scoliosis (AIS) patients have focused mainly on curve, maturity, and bone-related factors. Previous studies have shown significant associations between curve severity and morphological evidences of relative shorter spinal cord tethering in AIS, and increased prevalence of abnormal somatosensory cortical-evoked potentials and low-lying cerebellar tonsil in severe AIS. Earlier evidence suggests that there might be neural morphological predictors for curve progression. PURPOSE: The purpose of this study was to identify any morphological predictors associated with cord tethering, as measured by magnetic resonance imaging (MRI), for curve progression in AIS patients. STUDY DESIGN/SETTING: This is a prospective cohort study. PATIENT SAMPLE: A total of 81 female AIS subjects between 10 and 14 years were included, without surgical intervention during the follow-up period. OUTCOME MEASURES: Magnetic resonance imaging scans of hindbrain and whole spine and areal bone mineral density (BMD) at bilateral femoral necks were performed. METHODS: All AIS patients were longitudinally followed up starting from initiation of bracing beyond skeletal maturity in 6-month intervals. Clinical and radiographic data were recorded at each clinic visit. Bone mineral density and MRI measurements including ratio of spinal cord to vertebral column length, ratio of anteroposterior (AP) and transverse (TS) diameter of cord, lateral cord space (LCS) ratio, cerebellar tonsil level, and conus medullaris position were obtained at baseline. Only compliant patients with a minimum 2-year follow-up were analyzed. Adolescent idiopathic scoliosis girls were assigned into three groups according to bracing outcome: Group A, nonprogression (curvature increase of less than or equal to 5°); Group B, progression (curvature increase of greater than or equal to 6°); Group C, progression with surgery indication (Cobb angle of greater than or equal to 50° after skeletal maturity despite bracing). The predictors for curve progression were evaluated using univariate analysis and multivariate ordinal regression model. RESULTS: The average duration of follow-up was 3.4 (range, 2.0-5.6) years. There were 46 girls (57%) in Group A, 19 (23%) in Group B, and 16 (20%) in Group C. No significant intergroup differences were found in spinal cord length, tonsil level, and conus position. Group C had significantly longer vertebral column length, smaller cord-vertebral length ratio, and higher AP/TS cord ratio compared with Group A, whereas LCS ratio in Group C was significantly increased compared with both Group A and Group B. In regression model, five significant independent predictors including cord-vertebral length ratio (odds ratio [OR]: 1.993 [95% confidence interval {CI}: 1.053-3.771], p=.034), LCS ratio (OR: 2.639 [95% CI: 1.128-6.174], p=.025), initial Cobb angle (OR: 1.156 [95% CI: 1.043-1.281], p=.006), menarche age (OR: 1.688 [95% CI: 1.010-2.823], p=.046), and BMD (OR: 2.960 [95% CI: 1.301-6.731], p=.010) and a marginally significant predictor namely AP/TS cord ratio (OR: 1.463 [95% CI: 0.791-2.706], p=.096) were obtained. CONCLUSIONS: On baseline MRI measurement, cord-vertebral length ratio and LCS ratio are identified as new significant independent predictors for curve progression in AIS, whereas AP/TS cord ratio is suggested as a potential predictor requiring further validations. The earlier MRI parameters can be taken into accounts for prognostication of bracing outcome.

Effect of upright position on tonsillar level in adolescent idiopathic scoliosis.

PURPOSE: The aim of this study was to investigate the effect of an upright position on cerebellar tonsillar level in patients with adolescent idiopathic scoliosis (AIS). METHODS: Twenty-five patients with clinically diagnosed AIS and 18 normal controls were examined in both supine and upright positions using 0.25T MRI. The position of the inferior cerebellar tonsil tip relative to a reference line connecting the basion to the opisthion (BO line) was measured in millimetres. RESULTS: None of the 18 normal control subjects had cerebellar tonsillar descent below the BO line in either supine or the upright position. Forty-eight percent of AIS patients had tonsillar descent in the upright position, compared to 28 % in the supine position. In the upright position, cerebellar tonsillar position was lower in AIS patients than in normal subjects (mean -0.7 ± 1.5 vs. +2.1 ± 1.7, p < 0.00001). AIS patients also had a large degree of tonsillar excursion between upright and supine positions compared to normal subjects (mean -1.9 ± 2.3 vs. -0.1 ± 0.2, p < 0.00001). CONCLUSIONS: When considering the theoretical likelihood that a low tonsillar position may affect spinal cord function, one should bear in mind that tonsillar descent in AIS is significantly greater in the upright position. KEY POINTS: • AIS patients exhibited greater cerebellar tonsillar descent in upright than supine position. • Cerebellar tonsillar position was lower in AIS patients than normal subjects. • AIS patients exhibited greater tonsillar excursion between supine and upright positions.

A population-based cohort study of 394,401 children followed for 10 years exhibits sustained effectiveness of scoliosis screening.

BACKGROUND CONTEXT: The value of scoliosis screening has been recently shown in a multicenter randomized controlled trial. However, the long-term sustainability of the clinical effectiveness of scoliosis screening as a routine health service remains unknown. PURPOSE: The aim of this study was to assess the sustainability of the clinical effectiveness of school scoliosis screening. STUDY DESIGN/SETTING: A large population-based cohort study with a 10-year follow-up was conducted. PATIENT SAMPLE: A total of 394,401 students who were in the fifth grade during the five academic years from 1995/1996 to 1999/2000 formed five consecutive annual cohorts. The students were eligible for the Hong Kong scoliosis screening program, with their screening history and medical records until their nineteenth birthdays being assessed. OUTCOME MEASURES: The outcome measures considered in the study were development of adolescent idiopathic scoliosis by the 19 years of age and the Cobb angle. METHODS: The clinical effectiveness of scoliosis screening was assessed by referral rate for radiographic diagnosis, sensitivity, specificity, and predictive values. RESULTS: A total of 306,144 students (78%) participated in scoliosis screening, which used a two-tier system. The prevalence of curves of 20° or greater was 1.8% (95% confidence interval [CI], 1.7-1.8%), whereas the referral rate for radiography, the sensitivity, and the positive predictive value (PPV) for curves of 20° or greater were 4.1% (95% CI, 4.0-4.2%), 91% (95% CI, 90-92%), and 40% (95% CI, 39-41%), respectively. Across the five consecutive annual cohorts, the prevalence and sensitivity for curves of 20° or greater increased by 0.23% (95% CI, 0.21-0.25%; p<.001) and 0.76% (95% CI, 0.43-1.04%; p<.001) per year, respectively; however, the PPV was reduced by 1.71% (95% CI, 1.09-2.33%; p<.001) per year. CONCLUSIONS: This report describes the first large population-based study with a long-term follow-up indicating that a scoliosis screening program can have sustained clinical effectiveness in identifying patients with adolescent idiopathic scoliosis needing clinical observation. As the prevalence of adolescent idiopathic scoliosis increases, scoliosis screening should be continued as a routine health service in schools or by general practitioners if there is no scoliosis screening policy.

Are volumetric bone mineral density and bone micro-architecture associated with leptin and soluble leptin receptor levels in adolescent idiopathic scoliosis?--A case-control study.

BACKGROUND: Adolescent idiopathic scoliosis (AIS) is associated with low bone mineral density (BMD). The underlying etiology and how it may relate to the development of osteopenia remains unknown. Leptin has been postulated as one of the etiologic factors of AIS because of its profound effects on bone metabolism and pubertal growth. Its modulator, soluble leptin receptor (sOB-R), may affect leptin bioavailability and signaling. This study aimed to investigate whether serum leptin and sOB-R levels may be associated with bone quality, and whether these relationships may differ between young adolescent girls with and without AIS. METHODS: This was a case-control study involving 94 newly diagnosed AIS girls (Cobb angle 12-48°) aged 12 to 14 years old and 87 age and gender-matched normal controls. Subjects with BMI>23.0 Kg/m(2) were excluded. Anthropometric measurements including body weight, height, arm span and sitting height were taken. Serum total leptin and sOB-R were assayed with ELISA. Non-dominant distal radius was scanned with High Resolution pQCT for assessing bone quality in terms of bone morphometry, volumetric BMD (vBMD) and trabecular bone micro-architecture. RESULTS: Compared with normal controls, AIS girls had numerically higher sOB-R (p = 0.006), lower average vBMD (p = 0.048), lower cortical vBMD (p = 0.029), higher cortical bone perimeter (p = 0.014) and higher trabecular area (p = 0.027), but none remained statistically significant after the Hochberg-Benjamini procedure. Correlation analysis on serum leptin level indicated that distinctive correlations with trabecular bone parameters occurred only in AIS. CONCLUSION: This study showed that bone quality in AIS girls was deranged as compared with controls. In addition, the distinct differences in correlation pattern between leptin and trabecular bone parameters indicated possible abnormalities in bone metabolism and dysfunction of the leptin signaling pathway in AIS.

Abnormal bone quality versus low bone mineral density in adolescent idiopathic scoliosis: a case-control study with in vivo high-resolution peripheral quantitative computed tomography.

BACKGROUND CONTEXT: Adolescent idiopathic scoliosis (AIS) is associated with low bone mass that could persist into early adulthood and is an important prognostic factor for curve progression. Previous studies were confined to areal bone mineral density measurement that was a two-dimensional investigation for a three-dimensional structure. Evaluation of volumetric BMD (vBMD) and other bone quality parameters are important for gaining in-depth understanding of the etiopathogenesis of AIS. PURPOSE: The objective of this study was to carry out direct in vivo measurement of bone quality in AIS using high-resolution peripheral quantitative computed tomography (HR-pQCT) and compare the correlation of bone quality with osteopenia between AIS and control subjects. STUDY DESIGN/SETTING: A case-control study. PATIENT SAMPLE: Newly diagnosed AIS girls (n=112) and non-AIS girls (n=115) between 11 and 13 years. OUTCOME MEASURES: Areal bone mineral density of bilateral femoral necks and HR-pQCT of the nondominant distal radius were performed. METHODS: Areal bone mineral density of femoral necks was measured by dual-energy X-ray absorptiometry. Subjects were classified into the osteopenic (Z score less than or equal to -1) and nonosteopenic (Z score more than -1) groups. Bone quality parameters, including bone morphometry, trabecular bone microarchitecture, and vBMD, were measured by HR-pQCT (XtremeCT; Scanco Medical, Zurich, Switzerland). RESULTS: In AIS, the osteopenic group had lower measurements in cortical area, cortical thickness, average vBMD, compact bone vBMD, trabecular vBMD, trabecular bone volume to tissue volume ratio, and trabecular thickness compared with nonosteopenic AIS subjects. In contrast, among the non-AIS controls, the osteopenic group had lower measurements only in bone morphometry, average vBMD, and compact bone vBMD but not in trabecular vBMD and all other trabecular bone microarchitecture parameters. CONCLUSIONS: This is the first study using HR-pQCT to compare the correlation of bone quality with osteopenia in AIS and non-AIS subjects. It provides new insights and highlights the unique bone quality profile with predominant changes in the trabecular compartment in association with osteopenia being notably only detected in the AIS subjects. Further studies in this area are warranted for defining the metabolic nature and biomechanical sequelae of derangement in bone mass and bone quality and their roles in the etiopathogenesis of AIS.

A new risk classification rule for curve progression in adolescent idiopathic scoliosis.

BACKGROUND CONTEXT: Prognostic factors for curve progression of adolescent idiopathic scoliosis (AIS) have been reported previously. There is only one existing rule that classifies AIS patients into two groups by a curvature of 25°. PURPOSE: This study aimed to develop a more refined risk classification rule for AIS. STUDY DESIGN: This was a retrospective cohort study. PATIENT SAMPLE: We examined 2,308 untreated AIS patients, aged 10 years and older, who had a Risser sign of 2 and lesser and a curvature less than 30° at presentation. OUTCOME MEASURES: Outcome was taken as the time to progression to 30°. METHODS: Patients' clinical parameters were analyzed by Classification and Regression Tree analysis. RESULTS: The new classification rule identified four risk groups of curve progression. Patients with a curvature of 26° and more and less than 18° constituted the highest and lowest risk groups, respectively. The two intermediate groups were identified by the age (11.3 years), menarcheal status, and body height (154 cm). CONCLUSIONS: The risk classification rule only uses information at the first presentation and can aid physicians in deriving an efficient management.

Abnormal skeletal growth patterns in adolescent idiopathic scoliosis--a longitudinal study until skeletal maturity.

STUDY DESIGN: A cross-sectional and prospective longitudinal study on the anthropometric parameters and growth pattern of girls with adolescent idiopathic scoliosis (AIS). OBJECTIVE: To investigate the growth pattern of girls with AIS with different severities, using cross-sectional and prospective longitudinal data set in comparison with age-matched healthy controls. SUMMARY OF BACKGROUND DATA: AIS occurs in children during their pubertal growth spurt. Although there is no clear consensus on the difference in body height between girls with AIS and healthy controls, it is generally thought that the development and curve progression in girls with AIS is closely associated with their growth rate. There is no concrete prospective longitudinal study to document clearly the growth pattern and growth rate of subjects with AIS . METHODS: A total of 611 girls with AIS and 296 healthy age-matched controls were included in the study and among them, 194 girls with AIS and 116 healthy controls were followed up until skeletal maturity. The girls with AIS were grouped into moderate (AIS20) and severe curve (AIS40) groups on the basis of maximum curve magnitude at skeletal maturity. Clinical data and detailed anthropometric parameters were recorded. In the cross-sectional analysis, the groups of subjects were compared within different age groups (from the age of 12-16 yr). In the longitudinal study, linear mixed modeling with respect to age or years since menarche was employed to formulate the growth trajectory of different anthropometric parameters. RESULTS: In the cross-sectional analysis, the girls with AIS were generally taller, with longer arm span and lower body mass index than the healthy controls. The girls with AIS40 were found to be significantly shorter in height (P = 0.006) and arm span (P = 0.025) at the age of 12 years but caught up and overtook the control group at the age of 14 to 16 years. In the longitudinal study, the average growth rate of arm span in girls with AIS40 was significantly higher than that in girls with AIS20 (> 30%) (P = 0.004) and controls (> 70%) (P = 0.0004). The age of menarche of girls with AIS40 was significantly delayed by 5.9 months and 3.8 months when compared with the control group and girls with AIS20, respectively (P < 0.05). CONCLUSION: The growth patterns of girls with AIS with confirmed curve severities were significantly different from healthy age-matched controls. Girls with severe AIS had delayed menarche with faster skeletal growth rate during the age of 12 to 16 years. Monitoring the rate of change of arm span of girls with AIS could be an important additional clinical parameter in helping predict curve severity in girls with AIS.