Pelvic tilt and trunk inclination: new predictive factors in curve progression during the Milwaukee bracing for adolescent idiopathic scoliosis

Introduction

Previous studies had shown that sagittal spinal and pelvic morphology may be associated with the development and progression of adolescent idiopathic scoliosis, but the predictive value of initial spinal and pelvic morphology on the curve progression during brace treatment is unknown. The objective of this study was to evaluate the relation between initial spinopelvic morphology and the risk of curve progression of adolescent idiopathic scoliosis with the Milwaukee brace.

Materials and methods

From 2002 to 2007, adolescent idiopathic scoliosis (single thoracic curve with apex at or above T8) was treated with the Milwaukee brace in 60 girls. Initial standing, full-length lateral radiographs were made and seven sagittal radiographic parameters of spinal and pelvic alignment were measured. Patients were followed until skeletal maturity or progression of Cobb angle >45°. The progression of curve was defined as an increase of Cobb angle ≥6° at final follow-up or progression to surgery during brace treatment.

Results

The 45 patients (75.0 %) who had successful control of curve progression were initially significantly more skeletally mature (higher mean Risser sign) than the 15 patients (25.0 %) who had curve progression. The initial mean Cobb angle was similar between the stable and progressed groups. The mean pelvic tilt, T1-spinopelvic inclination and T9-spinopelvic inclination angles were significantly greater in the stable group than in the progressed group and these three angles were independent predictors for curve progression during brace treatment. There were no significant differences between the stable and progressed groups in initial mean pelvic incidence, sacral slope, thoracic kyphosis or lumbar lordosis angles. Pre-bracing pelvic tilt ≤?0.5° was strongly predictive and T1-spinopelvic inclination ≤3.5° was moderately predictive of curve progression during the Milwaukee brace treatment.

Conclusions

Initial pelvic tilt and spinopelvic inclination angles may predict the curve progression and treatment outcome of adolescent idiopathic scoliosis with the Milwaukee brace.     

Idiopathic scoliosis in Korean schoolchildren: a prospective screening study of over 1 million children

Cross-sectional epidemiologic scoliosis screening was carried out to determine the current prevalence of scoliosis in the Korean population and to compare with the results of previous studies. Between 2000 and 2008, 1,134,890 schoolchildren underwent scoliosis screening. The children were divided into two age groups, 10–12-year-olds (elementary school) and 13–14-year-olds (middle school), to calculate age- and sex-specific prevalence rates. Children with a scoliometer reading ≥5° were referred for radiograms. Two surgeons independently measured curve types, magnitudes, and Risser scores (inter-observer r = 0.964, intra-observer r = 0.978). Yearly and overall prevalence rates of scoliosis were calculated. There were 584,554 boys and 550,336 girls in the sample, with a male to female ratio of 1.1:1. There were 77,910 (6.2%) children (26,824 boys and 51,086 girls) with scoliometer readings >5°, and 37,339 of them had positive results with Cobb angles ≥10° (positive predictive value, 46.4%). The overall scoliosis prevalence rate was 3.26%; girls had a higher prevalence (4.65%) than boys (1.97%). Prevalence rates increased progressively from 1.66 to 6.17% between 2000 and 2008, with the exception of 2002. According to age and gender, 10–12-year-old girls had the highest scoliosis prevalence rates (5.57%), followed by 13–14-year-old girls (3.90%), 10–12-year-old boys (2.37%), and 13–14-year-old boys (1.42%). In girls and boys, prevalence rates dropped by 64.53 and 60.65% among 10–12-year-olds and 13–14-year-olds, respectively (P = 0.00). The proportion of 10°–19° curves was 95.25 and 84.45% in boys and girls, respectively; and the proportion of 20°–29° curves was 3.91 and 11.28%, which was a significant difference (P = 0.00). Thoracic curves were the most common (47.59%) followed by thoracolumbar/lumbar (40.10%), double (9.09%), and double thoracic (3.22%) curves. A comparison of the curve patterns revealed significant differences between genders (P = 0.00). We present this report as a guide for studying the prevalence of idiopathic scoliosis in a large population, and the increasing trend in the prevalence of idiopathic scoliosis emphasizes the need for awareness.     

凸侧骨骺阻滞术对阻止半椎体所致脊柱侧凸的进展疗效分析

目的：探讨凸侧骨骺阻滞术对先天性脊柱侧凸患者的治疗效果。方法：回顾分析1998年10月至2008年2月行Ⅰ期前后路联合骨骺阻滞术的胸腰椎半椎体畸形22例患者,其中男12例,女10例。测量术前、术后及末次随访时主弯及代偿弯角度,同时计算术后进展率及年进展量。观察侧凸进展率和年进展量与年龄、性别、半椎体数目、半椎体位置、术前主弯Cobb角及代偿弯Cobb角之间有无相关性,比较不同年龄、性别、半椎体数目、半椎体位置以及术前主弯Cobb角对术后侧弯进展的影响。结果：22例主弯Cobb角术前为（40.5±9.8）°,术后3个月为（39.5±11.1）°,末次随访时为（46.8±13.9）°。代偿弯Cobb角术前为（20.1±10.8）°,术后3个月为（23.0±11.1）°,末次随访为（29.9±11.5）°。术前主弯及代偿弯Cobb角与术后3个月比较,差异无统计学意义（P>0.05）,末次随访与术前、术后3个月比较差异有统计学意义（P<0.01）。术后共有20例出现主弯角度进展,平均进展率为（19.2±17.9）%,年进展量为（1.5±1.4）°,共有20例患者出现代偿弯进展,平均进展率为（39.6±37.0）%,年进展量为（1.4±1.3）°。3例因术后侧凸进展明显行侧凸矫形内固定。22例患者手术时年龄及半椎体数分别与术后主弯进展率之间存在显著相关性,手术时年龄、主弯角度及术前代偿弯角度分别与术后主弯年进展量之间存在显著相关性（P<0.05）。结论：凸侧骨骺阻滞术不能获得即刻的矫形效果,长期随访发现,也不能有效阻止侧凸的进展,可认为凸侧骨骺阻滞术对于先天性半椎体畸形患者而言是一种无效的手术方式。     

Coronal plane segmental flexibility in thoracic adolescent idiopathic scoliosis assessed by fulcrum-bending radiographs

Knowledge about segmental flexibility in adolescent idiopathic scoliosis is crucial for a better biomechanical understanding, particularly for the development of fusionless, growth-guiding techniques. Currently, there is lack of data in this field. The objective of this study was, therefore, to compute segmental flexibility indices (standing angle minus corrected angle/standing angle). We compared segmental disc angles in 76 preoperative sets of standing and fulcrum-bending radiographs of thoracic curves (paired, two-tailed t tests, p < 0.05). The mean standing Cobb angle was 59.7° (range 41.3°–95°) and the flexibility index of the curve was 48.6% (range 16.6–78.8%). The disc angles showed symmetric periapical distribution with significant decrease (all p values <0.0001) for every cephalad (+) and caudad (−) level change. The periapical levels +1 and −1 wedged at 8.3° and 8.7° (range 3.5°–14.8°), respectively. All angles were significantly smaller on the-bending views (p values <0.0001). We noted mean periapical flexibility indices of 46% (+1), 49% (−1), 57% (+2) and 81% (−2), which were significantly less (p < 0.001) than for the group of remote levels 105% (+3), 149% (−3), 231% (+4) and 300% (−4). The discal and bony wedging was 60 and 40%, respectively, and mean values 35° and 24° (p < 0.0001). Their relationship with the Cobb angle showed a moderate correlation (r = 0.56 and 0.45). Functional, radiographic analysis of idiopathic thoracic scoliosis revealed significant, homogenous segmental tethering confined to four periapical levels. Future research will aim at in vivo segmental measurements in three planes under defined load to provide in-depth data for novel therapeutic strategies.     

The ��X-Factor�� Index: a new parameter for the assessment of adolescent idiopathic scoliosis correction

The correction rate (CR) and fulcrum bending correction index (FBCI) based on the fulcrum bending radiograph (FBR) were parameters introduced to measure the curve correcting ability; however, such parameters do not account for contributions by various, potential extraneous “X-Factors” (e.g. surgical technique, type and power of the instrumentation, anesthetic technique, etc.) involved in curve correction. As such, the purpose of the following study was to propose the concept of the “X-Factor Index” (XFI) as a new parameter for the assessment of the correcting ability of adolescent idiopathic scoliosis (AIS). A historical cohort radiographic analysis of the FBR in the setting of hook systems in AIS patients (Luk et al. in Spine 23:2303–2307, 1998) was performed to illustrate the concept of XFI. Thirty-five patients with AIS of the thoracic spine undergoing surgical correction were involved in the analysis. Plain posteroanterior (PA) plain radiographs were utilized and Cobb angles were obtained for each patient. Pre- and postoperative PA angles on standing radiograph and preoperative fulcrum bending angles were obtained for each patient. The fulcrum flexibility, curve CR, and FBCI were determined for all patients. The difference between the preoperative fulcrum bending angle and postoperative PA angle was defined as Angle_XF, which accounted for the correction contributed by “X-Factors”. The XFI, designed to measure the curve correcting ability, was calculated by dividing Angle_XF by the fulcrum flexibility. The XFI was compared with the curve CR and FBCI by re-evaluating the original data in the original paper (Luk et al. in Spine 23:2303–2307, 1998). The mean standing PA and FBR alignments of the main thoracic curve were 58.3° and 24.5°, respectively. The mean fulcrum flexibility was 58.8%. The mean postoperative standing PA alignment was 24.7°. The mean curve CR was 58.0% and the mean FBCI was 101.1%. The mean XFI was noted as 1.03%. The CR was significantly positively correlated to curve flexibility (r = 0.66; p < 0.01).The FBCI (r = −0.47; p = 0.005) and the XFI (r = −0.45; p = 0.007) were significantly negatively correlated to curve flexibility. The CR was not correlated to Angle_XF (r = 0.29; p = 0.089).The FBCI (r = 0.97; p < 0.01) and the XFI (r = 0.961; p < 0.01) were significantly positively correlated to Angle_XF. Variation in XFI was noted in some cases originally presenting with same FBCI values. The XFI attempts to quantify the curve correcting ability as contributed by “X-Factors” in the treatment of thoracic AIS. This index may be a valued added parameter to accompany the FBCI for comparing curve correction ability among different series of patients, instrumentation, and surgeons. It is recommended that the XFI should be used to document curve correction, compare between different techniques, and used to improve curve correction for the patient.     

Analysis and simulation of progressive adolescent scoliosis by biomechanical growth modulation

Scoliosis is thought to progress during growth because spinal deformity produces asymmetrical spinal loading, generating asymmetrical growth, etc. in a ‘vicious cycle.’ The aim of this study was to test quantitatively whether calculated loading asymmetry of a spine with scoliosis, together with measured bone growth sensitivity to altered compression, can explain the observed rate of scoliosis progression in the coronal plane during adolescent growth. The simulated spinal geometry represented a lumbar scoliosis of different initial magnitudes, averaged and scaled from measurements of 15 patients’ radiographs. Level-specific stresses acting on the vertebrae were estimated for each of 11 external loading directions (‘efforts’) from published values of spinal loading asymmetry. These calculations assumed a physiologically plausible muscle activation strategy. The rate of vertebral growth was obtained from published reports of growth of the spine. The distribution of growth across vertebrae was modulated according to published values of growth sensitivity to stress. Mechanically modulated growth of a spine having an initial 13° Cobb scoliosis at age 11 with the spine subjected to an unweighted combination of eleven loading conditions (different effort direction and magnitude) was predicted to progress during growth. The overall shape of the curve was retained. The averaged final lumbar spinal curve magnitude was 32° Cobb at age 16 years for the lower magnitude of effort (that produced compressive stress averaging 0.48 MPa at the curve apex) and it was 38° Cobb when the higher magnitudes of efforts (that produced compressive stress averaging 0.81 MPa at the apex). An initial curve of 26° progressed to 46° and 56°, respectively. The calculated stresses on growth plates were within the range of those measured by intradiscal pressures in typical daily activities. These analyses predicted that a substantial component of scoliosis progression during growth is biomechanically mediated. The rationale for conservative management of scoliosis during skeletal growth assumes a biomechanical mode of deformity progression (Hueter-Volkmann principle). The present study provides a quantitative basis for this previously qualitative hypothesis. The findings suggest that an important difference between progressive and non-progressive scoliosis might lie in the differing muscle activation strategies adopted by individuals, leading to the possibility of improved prognosis and conservative or less invasive interventions.     

Endoscopic surgery on the thoracolumbar junction of the spine

It is a measurement of Cobb’s angles between adolescent (AIS) and juvenile (JIS) idiopathic scoliosis who had stable curves (variation <5 degrees) in more than three visits. Main objective of this paper is to measure inter- and intra-observer reliability of measurements between AIS and JIS who had stable curves in regular follow-up. Twenty-nine JIS and 44 AIS patients who had stable curves without bracing were identified using PACS system. Two observers independently measured Cobb’s angle twice on first, during follow-up and final radiogram using computer-based digital radiogram. Both observers were given pre-decided level of upper and lower end plates. Inter- and intra-observer reliability of the measurement was calculated using Pearson correlation-coefficient test between JIS and AIS group. There was no significant difference in Cobb’s angle in all measurements by both observers either in JIS (p = 0.756, range 0.706–0.815; ANOVA) or AIS (p = 0.871, range 0.795–0.929; ANOVA) group which suggested that there is no significant difference in Cobb’s angle in repeated measurements. Intra-observer reliability for JIS (r = 0.600, range 0.521–0.751; Pearson test) was less than AIS (r = 0.969, range 0.943–0.984; Pearson test); and similarly, inter-observer reliability for JIS (r = 0.547, Pearson test) was also less than AIS (r = 0.961, Pearson test) which indicates that Cobb’s angle measurement is less reliable in patients who have juvenile idiopathic scoliosis. Using the identical condition for measurements in both the groups, we could find only one reason for less reliability in JIS group and that is poor demarcation of the vertebral end-plates in this group. This poor inter- and intra-observer reliability in JIS due to ill-defined endplates can be reduced by measuring all previous curves along with latest curves at the same time during the follow-up of patients with JIS to decide about the progression of curves and treatment options.     

Porcine model of early onset scoliosis based on animal growth created with posterior mini-invasive spinal offset tethering A preliminary report

Several models of scoliosis were developed in the past 10 years. In most of them, deformations are induced in old animals and required long time observation period and a chest wall ligation ± resection. The purpose of the study was to create a scoliosis model with a size similar to an early onset scoliosis and an important growth potential without chest wall injuring. An original offset implant was fixed posteriorly and connected with a cable in seven (6 + 1 control) one-month-old Landrace pigs. The mean initial spinal length (T1-S1) was 25 cm and the mean weight was 9 kg. After 2 months observation, spinal deformities were assessed with a three dimension stereographic analysis. In four animals, the cable was sectioned and the deformities followed-up for next 2 months. No post-operative complication was observed. Mean weight growth was 10 kg/month and mean spine lengthening (T1-S1) was 7 cm/month. In 2 months, we obtained structural scoliotic curves with vertebral and disk wedging which were maximal at the apex of the curve. Mean frontal and sagittal Cobb angles was 45°. Chest wall associated deformities were similar to those observed in scoliotic deformities and were correlated to spinal deformities (p = 0.03). The cable section resulted in a partial curve regression influenced by disk elasticity and could probably be influenced by gravity loads (Decrease of the Cobb angle of 30% in the sagittal plane and 45% in the frontal plane). According to the results, the model creates a structural scoliosis and chest wall deformity that is similar to an early onset scoliosis. The spinal deformities were obtained quickly, and were consistent between animals in term of amount and characteristic.     

青少年特发性脊柱侧弯Cobb角与直线棘突角相关性分析

目的:分析轻中度青少年特发性脊柱侧弯(adolescent idiopathic scoliosis,AIS)患者Cobb角与X线片直线棘突角(spinous process angle,SPA)、体表直线SPA相关性,探讨直线SPA评估脊柱侧弯的可能性。方法:Cobb角与X线片直线棘突角相关性研究为单中心回顾性研究,纳入自2019年1月至2021年12月脊柱全长正位X线片的AIS患者,测量患者直线SPA与Cobb角,并对两者进行相关性分析。Cobb角与体表直线SPA相关性研究为前瞻性研究,纳入自2022年12月1日至2022年12月9日就诊的AIS患者,测量Cobb角与站立位下体表直线SPA,并对两者进行相关性分析。结果:回顾性研究中共纳入113例AIS患者,男26例,女87例,年龄10～18(14.02±2.16)岁;轻度AIS患者71例,中度AIS患者42例。AIS患者Cobb角与直线SPA存在明显负相关(r=-0.564,P<0.001),两者线性回归方程为:Cobb角=169.444-0.878×SPA;轻度侧弯患者Cobb角与直线SPA存在明显负相关(r=-0.269...     

Reliability analysis for radiographic measures of lumbar lordosis in adult scoliosis: a case–control study comparing 6 methods

Several methods are used to measure lumbar lordosis. In adult scoliosis patients, the measurement is difficult due to degenerative changes in the vertebral endplate as well as the coronal and sagittal deformity. We did the observational study with three examiners to determine the reliability of six methods for measuring the global lumbar lordosis in adult scoliosis patients. Ninety lateral lumbar radiographs were collected for the study. The radiographs were divided into normal (Cobb < 10°), low-grade (Cobb 10°–19°), high-grade (Cobb  ≥ 20°) group to determine the reliability of Cobb L1–S1, Cobb L1–L5, centroid, posterior tangent L1–S1, posterior tangent L1–L5 and TRALL method in adult scoliosis. The 90 lateral radiographs were measured twice by each of the three examiners using the six measurement methods. The data was analyzed to determine the inter- and intra-observer reliability. In general, for the six radiographic methods, the inter- and intra-class correlation coefficients (ICCs) were all ≥0.82. A comparison of the ICCs and 95% CI for the inter- and intra-observer reliability between the groups with varying degrees of scoliosis showed that, the reliability of the lordosis measurement decreased with increasing severity of scoliosis. In Cobb L1–S1, centroid and posterior tangent L1–S1 methods, the ICCs were relatively lower in the high-grade scoliosis group (≥0.60). And, the mean absolute difference (MAD) in these methods was high in the high-grade scoliosis group (≤7.17°). However, in the Cobb L1–L5 and posterior tangent L1–L5 method, the ICCs were ≥0.86 in all groups. And, in the TRALL method, the ICCs were ≥0.76 in all groups. In addition, in the Cobb L1–L5 and posterior tangent L1–L5 method, the MAD was ≤3.63°. And, in the TRALL method, the MAD was ≤3.84° in all groups. We concluded that the Cobb L1–L5 and the posterior tangent L1–L5 methods are reliable methods for measuring the global lumbar lordosis in adult scoliosis. And the TRALL method is more reliable method than other methods which include the L5–S1 joint in lordosis measurement.     

The effect of intra-operative skeletal (skull femoral) traction on apical vertebral rotation

The study design is a retrospective review of consecutive case series. Our goal was to identify and quantify the effect of skeletal traction on the apical vertebral rotation (AVR). Intra-operative skeletal traction has been used for the correction of large magnitude idiopathic and neuromuscular scoliosis. The ability of skeletal traction to correct the rotational deformity of the spine has not been characterized. Following REB approval, retrospective analysis of 22 (AIS = 14, neuromuscular = 8) consecutive pediatric patients having surgical posterior instrumented correction and fusion for their scoliosis was performed. Intra-operative skeletal traction with approximately 50% body weight was achieved with smooth distal femoral pins. Counter-traction up to 25% was used through Gardner–Wells tongs. The AVR of the major curve was assessed using the Nash–Moe grading system by a radiologist and a senior spine surgeon not involved in the treatment of these cases. Statistical analysis was performed to determine the significance. The overall mean AVR of the major structural curve was 3.1 ± 0.8 and reduced to 2.4 ± 0.6 (p = 0.0001) following traction. The AVR decreased by one or more Nash–Moe grades with traction in 14/22 (64%) patients. The Cobb angle corrected from a mean of 88.2° to 49.1° (44.3%, p = 0.00001) with traction. The decrease in AVR correlated with the higher magnitude Cobb angles (correlation 0.53, p = 0.014). Patients with pre-traction AVR ≥ 3 showed the largest change with traction (3.4–2.5, p = 0.000004). There was very good association between the radiologist and the spine surgeon, 0.72(standing films) and 0.63(traction films). The minor structural curve corrected from a mean Cobb of 53.5° to 33.8° (37.8%) with AVR decreasing from a mean of 1.9 to 1.4 (p = 0.014). Significant apical derotation occurs with the use of intra-operative skull-skeletal traction in the correction of high magnitude scoliotic curves. This derotation can facilitate spinal exposure, placement of pedicles screws and final correction in these patients.     

The relationship between body composition and the urinary excretion of deoxypyridinoline and galactosyl-hydroxylysine in children and adolescents

The study intends to investigate the relationship of body composition (%fat, percent body fat; FM, fat mass; FFM, fat free mass; FA and MA cross-sectional fat and muscle area) to the urinary excretion of deoxypyridinoline (DPD) and galactosyl-hydroxylysine (Gal-Hyl). 231 healthy children and adolescents (age 5–19 years; 112 males) of the DONALD study were analyzed for FM and FFM by measuring 4 skinfold thicknesses, for DPD and Gal-Hyl in urine samples and for bone parameters, FA and MA at the forearm by peripheral quantitative computed tomography. In contrast to adrenarchal females, adrenarchal males with low %fat had low levels of DPD and Gal-Hyl. %fat was correlated with DPD in pre-adrenarchal males (r = 0.290) and females (r = 0.298). Cortical bone mineral density (BMDcort) was correlated with DPD (r = −0.351) in adrenarchal males. Controlled for BMDcort, FM was correlated with DPD in pre-adrenarchal males (r = 0.348), and FA was correlated with DPD in pre-adrenarchal females (r = 0.294). FFM was negatively correlated with Gal-Hyl in adrenarchal males (r = −0.436) and females (r = −0.338). Less than 40% of variance of excreted DPD and Gal-Hyl was explained by regression models based on parameters of body composition. The effect of body composition explains the minor part of variance of the urinary excretion of DPD and Gal-Hyl. The association of body composition to excreted DPD and Gal-Hyl was not explained by the effect of adipose tissue on bone formation and bone resorption.     

Subcutaneous Fat and Body Fat Mass Have Different Effects on Bone Development at the Forearm in Children and Adolescents

The present study investigated whether subcutaneous fat differs in the impact on bone development from fat mass (FM). We analyzed 295 healthy children and adolescents (age 5–19 years, 139 males) for FM by measuring four skinfold thicknesses and for bone development and body composition at the forearm by peripheral quantitative computed tomography in a cross-sectional investigation. Relative cross-sectional fat area (FA) was a surrogate for relative subcutaneous FM at the forearm and was associated positively with percent fat in prepubertal individuals and pubertal females but negatively in pubertal males. Percent FM was associated with trabecular bone mineral density (BMDtrab) in prepubertal individuals (females r = 0.394, males r = 0.242) and pubertal individuals (females r = 0.215, males r = −0.275). Bone mineral count was correlated with percent FM in pubertal males (r = −0.287). FA was correlated with BMDtrab (r = 0.285) and with cortical bone mineral density (BMDcort, r = −0.296) in pubertal females. The ratio FA/FM was negatively correlated with BMDcort (r = −0.299) in pubertal females. Pubertal females with relatively high subcutaneous fat area (high ratio FA/FM) were characterized by lower bone strength (P = 0.047). FM and the relative amount of subcutaneous fat have effects on bone formation and resorption that depend on gender and puberty. Especially in pubertal females, higher levels of subcutaneous fat may decrease bone strength due to increased cortical remodeling.     

The effect of calmodulin antagonists on scoliosis: bipedal C57BL/6 mice model

C57BL6 mice are melatonin deficient from birth and have been shown to develop scoliosis when rendered bipedal. Our previous work suggested that tamoxifen and trifluoperozine may change the natural course of scoliosis in a chicken model. The objective of this study was to analyze whether the incidence of scoliosis or the magnitude of curves may be decreased by the administration of pharmacological agents tamoxifen or trifluoperozine in a mice scoliosis model. Sixty female 3-week-old C57BL6 mice underwent amputations of forelimbs and tails. Available 57 mice were divided into three groups, Group-I received no medications whereas Groups II and III received 10 mg TMX and 10 mg TMX + 10 mg TFP per liter of daily water supply, respectively. PA scoliosis X-rays were obtained at 20th and 40th weeks. Deformities were compared for incidence and the severity of the curves as well as disease progression or regression. At 20th week, overall, upper thoracic (UT), lower thoracic (T), and lumbar (L) scoliosis rates were similar (P = 0.531; P = 0.209; P = 0.926; P = 0.215, respectively) but thoraco-lumbar (TL) scoliosis rate was higher inTMX group (P = 0.036). However, at 40th week, although TL and L rates were similar (P = 0.628, P = 0.080), overall rate as well as the rates of UT and T scoliosis of TMX group were significantly lower (P = 0.001, P = 0.011, P = 0.001, respectively). As for curve magnitudes, T mean Cobb angle at 20th week was significantly higher in the C group (14 ± 2.55) compared to TMX + TFP group (9 ± 2.708; P = 0.033); at 40th week, TL mean Cobb angle was lower in the TMX + TFP group (17.50 ± 3.45) compared to C (29.40 ± 5.98; P = 0.031); and TMX group had lower TL Cobb angles compared to C (8.67 ± 11.72) although not significant (P = 0.109). Double curve incidence at 40th week was significantly lower in TMX group compared to other groups (P = 0.001), triple curve incidence was lower in TMX + TFP and TMX groups, albeit not significant (P = 0.167). Between the 20th and 40th weeks, overall, double curve, and UT scoliosis rates showed an increase in C and TMX + TFP groups whereas TMX group showed a decline (P = 0.01, P = 0.002, P = 0.007, respectively). When specific regions were compared a similar significant difference was observed (P = 0.012 for upper thoracic; P = 0.018 for thoracic; P = 0.047 for thoraco-lumbar). This study has demonstrated that TMX is effective in changing the natural history of scoliotic deformities in C57BL6 mice model favorably.     

Spine slenderness and wedging in adolescent idiopathic scoliosis and in asymptomatic population: an observational retrospective study

The origin of the deformity due to adolescent idiopathic scoliosis (AIS) is not known, but mechanical instability of the spine could be involved in its progression. Spine slenderness (the ratio of vertebral height to transversal size) could facilitate this instability, thus playing a role in scoliosis progression. The purpose of this work was to investigate slenderness and wedging of vertebrae and intervertebral discs in AIS patients, relative to their curve topology and to the morphology of control subjects. A total of 321 AIS patients (272 girls, 14 ± 2 years old, median Risser sign 3, Cobb angle 35° ± 18°) and 83 controls were retrospectively included (56 girls, median Risser 2, 14 ± 3 years). Standing biplanar radiography and 3D reconstruction of the spine were performed. Geometrical features were computed: spinal length, vertebral and disc sizes, slenderness ratio, frontal and sagittal wedging angles. Measurement reproducibility was evaluated. AIS girls before 11 years of age had slightly longer spines than controls (p = 0.04, Mann–Whitney test). AIS vertebrae were significantly more slender than controls at almost all levels, almost independently of topology. Frontal wedging of apical vertebrae was higher in AIS, as expected, but also lower junctional discs showed higher wedging than controls. AIS patients showed more slender spines than the asymptomatic population. Analysis of wedging suggests that lower junctional discs and apex vertebra could be locations of mechanical instability. Numerical simulation and longitudinal clinical follow-up of patients could clarify the impact of wedging, slenderness and growth on the biomechanics of scoliosis progression. These slides can be retrieved under Electronic Supplementary Material.     

Disc and vertebral wedging in patients with progressive scoliosis

A retrospective longitudinal radiographic study of patients with progressive scoliosis was conducted to determine the relative amount of wedging between vertebrae and discs as a function of progression of the scoliosis curve, cause of the scoliosis, and anatomic curve region. Posteroanterior radiographs of 27 patients with idiopathic scoliosis and of 17 patients with scoliosis associated with cerebral palsy were studied. The amount of wedging of vertebrae and discs at the curve apex was measured by the Cobb method and expressed as a proportion of the curve's Cobb angle. On average, the relative amount of vertebral and disc wedging did not differ significantly between initial and follow-up radiographs made after progression of the scoliosis. In both groups of patients, the mean vertebral wedging was more than the disc wedging in the thoracic region; the converse was found in curves in the lumbar and thoracolumbar regions. The patients with scoliosis associated with cerebral palsy had curves that were longer and more commonly in the thoracolumbar and lumbar regions. The relative wedging did not change significantly with curve progression and did not appear to differ by diagnosis. In the management of scoliosis, including small curves, it should be recognized that both the vertebrae and discs have a wedging deformity.     

Treatment of idiopathic scoliosis with side-shift therapy: an initial comparison with a brace treatment historical cohort

A group of 44 patients with idiopathic scoliosis (mean age 13.6 years) with an initial Cobb angle between 20° and 32° received side-shift therapy (mean treatment duration 2.2 years). A group of 120 brace patients (mean age 13.6 years) with an initial Cobb angle in the same range (mean brace treatment 3.0 years) was the historical reference group. Failure was defined as an increase of Cobb angle greater than 5° within 4 months or a Cobb angle greater than 35° or a total increase of Cobb angle greater than 10°. The chance of success was not significantly different between the side-shift and the brace groups, whether tested for efficiency (66% vs 68%) or efficacy (85% vs 90%). The difference in the mean progression of the Cobb angle for the respective groups is small (for efficiency: 3° vs –2°, for efficacy: 2° vs –1°). Side-shift therapy appears to be a promising additional treatment for idiopathic scoliosis in adolescents with an inital Cobb angle between 20° and 32°. Received: 20 February 1999 Accepted: 10 July 1999     

Pain and disability correlated with disc degeneration via magnetic resonance imaging in scoliosis patients

Prior imaging studies of scoliosis patients attempted to demonstrate a relationship between plain radiographic curve patterns and curve progression and pain, or used magnetic resonance imaging (MRI) to focus on spinal cord abnormalities. Pain in scoliosis patients may differ from nondeformity patients, yet may still be discogenic. The purpose of this study was to assess the possible relationship of degenerative disc findings on MRI to scoliosis patients’ pain. This prospective study enrolled scoliosis and control patients, all of whom had assessment for back pain (visual analog scale) and disability (Oswestry Index) and spinal MRI to identify prevalence and distribution of degenerative disc findings. Specifically, we assessed 60 consecutive pediatric and adult idiopathic scoliosis patients who had progressed to surgical treatment, 60 age- and gender-matched asymptomatic controls, and 172 nondeformity symptomatic degenerative disc disease patients who had progressed to surgical treatment. All subjects had independent analysis of their preoperative MRI for disc degeneration, disc herniation, Schmorl’s nodes, and inflammatory end plate changes. Imaging findings of the scoliosis patients were compared to those from asymptomatic and symptomatic control groups. Our results found that both pediatric and adult scoliosis patients had significantly more pain and disability than did asymptomatic controls (P < 0.001). The adult idiopathic scoliosis patients had pain and disability similar to those of surgical degenerative disc disease control groups. Disc degeneration and herniation (contained) were not related to pain. However, in the pediatric scoliosis patients, those with Schmorl’s nodes often had greater pain than those without (P = 0.01). Adults with painful scoliosis, typically occurring at the apex of the scoliosis or at the lumbosacral junction, had a significantly higher frequency of inflammatory end plate changes on MRI than did controls (P < 0.001). Prior studies have demonstrated a correlation of inflammatory end plate changes to lumbar discogenic pain. In conclusions, scoliosis patients who have progressed to surgical intervention, pediatric patients have varying degrees of pain, and those with Schmorl’s nodes may be at greater risk for pain. Adult scoliosis patients have multifactorial pain of which one component may be related to degeneration of the lower lumbar discs similar to that in nondeformity patients. Additionally, adult scoliosis patients may have MRI findings consistent with discogenic pain at the apex of their curvature, most commonly at the proximal lumbar levels.     

The role of spinal concave–convex biases in the progression of idiopathic scoliosis

Inadequate understanding of risk factors involved in the progression of idiopathic scoliosis restrains initial treatment to observation until the deformity shows signs of significant aggravation. The purpose of this analysis is to explore whether the concave–convex biases associated with scoliosis (local degeneration of the intervertebral discs, nucleus migration, and local increase in trabecular bone-mineral density of vertebral bodies) may be identified as progressive risk factors. Finite element models of a 26° right thoracic scoliotic spine were constructed based on experimental and clinical observations that included growth dynamics governed by mechanical stimulus. Stress distribution over the vertebral growth plates, progression of Cobb angles, and vertebral wedging were explored in models with and without the biases of concave–convex properties. The inclusion of the bias of concave–convex properties within the model both augmented the asymmetrical loading of the vertebral growth plates by up to 37% and further amplified the progression of Cobb angles and vertebral wedging by as much as 5.9° and 0.8°, respectively. Concave–convex biases are factors that influence the progression of scoliotic curves. Quantifying these parameters in a patient with scoliosis may further provide a better clinical assessment of the risk of progression.     

Anterior thoracoscopic surgery followed by posterior instrumentation and fusion in spinal deformity

Many authors believe thoracoscopic surgery is associated with a lower level of morbidity compared to thoracotomy, for anterior release or growth arrest in spinal deformity. Others believe that anterior release achieved thoracoscopically is not as effective as that achieved with the open procedure. We evaluated the clinical results, radiological correction and morbidity following anterior thoracoscopic surgery followed by posterior instrumentation and fusion, to see whether there is any evidence for either of these beliefs. Twenty-nine patients undergoing thoracoscopic anterior release or growth arrest followed by posterior fusion and instrumentation were evaluated from a clinical and radiological viewpoint. The mean follow-up was 2 years (range 1–4 years). The average age was 16 years (range 5–26 years). The following diagnoses were present: idiopathic scoliosis (n = 17), neuromuscular scoliosis (n = 2), congenital scoliosis (n = 1), thoracic hyperkyphosis (n = 9). All patients were satisfied with cosmesis following surgery. Twenty scoliosis patients had a mean preoperative Cobb angle of 65.1° (range 42°–94°) for the major curve, with an average flexibility of 34.5% (42.7°). Post operative correction to 31.5° (50.9%) and 34.4° (47.1%) at maximal follow-up was noted. For nine patients with thoracic hyperkyphosis, the Cobb angle averaged 81° (range 65°–96°), with hyperextension films showing an average correction to 65°. Postoperative correction to an average of 58.6° was maintained at 59.5° at maximal follow-up. The average number of released levels was 5.1 (range 3–7) and the average duration of the thoracoscopic procedure was 188 min (range 120–280 min). There was a decrease in this length of time as the series progressed. No neurologic or vascular complications occurred. Postoperative complications included four recurrent pneumothoraces, one surgical emphysema, and one respiratory infection. Thoracoscopic anterior surgery appears a safe and effective technique for the treatment of paediatric and adolescent spinal deformity. A randomised controlled trial, comparing open with thoracoscopic methods, is required. Received: 11 October 1999 Revised: 20 April 2000 Accepted: 16 May 2000