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Adolescent idiopathic scoliosis (AIS) is the most common spinal disorder in children. A severity index was recently proposed to identify the stable from the progressive scoliosis at the first standardized biplanar radiographic exam. The aim of this work was to extend the validation of the severity index and to determine if curve location influences its predictive capabilities. AIS patients with Cobb angle between 10° and 25°, Risser 0–2, and no previous treatment were included. They underwent standing biplanar radiography and 3D reconstruction of the spine and pelvis, which allowed to calculate their severity index. Patients were grouped by curve location (thoracic, thoracolumbar, lumbar). Patients were followed up until skeletal maturity (Risser ≥ 3) or brace prescription. Their outcome was compared to the prediction made by the severity index. In total, 205 AIS patients were included; 82% of them (155/189, 95% confidence interval [74–90%]) were correctly classified by the index, while 16 patients were unclassified. Positive predictive ratio was 78% and negative predictive ratio was 86%. Specificity (78%) was not significantly affected by curve location, while patients with thoracic and lumbar curves showed higher sensitivity (≥ 89%) than those with thoracolumbar curves (74%). In this multicentric cohort of 205 patients, the severity index was used to predict the risk of progression from mild to moderate scoliosis, with similar results of typical major curve types. This index represents a novel tool to aid the clinician and the patient in the modulation of the follow-up and, for progressive patients, their decision for brace treatment. • The severity index of adolescent idiopathic scoliosis has the potential to detect patients with progressive scoliosis as early as the first exam. • Out of 205 patients, 82% were correctly classified as either stable or progressive by the severity index. • The location of the main curve had small effect on the predictive capability of the index.

International audience; Study Design: This was a multicentric cross-sectional descriptive study.Objective: To analyze patterns of 3D rib cage deformity in subjects with adolescent idiopathic scoliosis (AIS) and their relationship with the spinal deformity.Summary of Background Data: Subjects with AIS present with rib cage deformity that can affect respiratory functions. The 3D rib cage deformities in AIS and their relationship to the spinal deformity are still unelucidated.Methods: A total of 200 AIS and 71 controls underwent low-dose biplanar x-rays and had their spine and rib cage reconstructed in 3-dimensional (D). Classic spinopelvic parameters were calculated in 3D and: rib cage gibbosity, thickness, width, volume and volumetric spinal penetration index (VSPI). Subjects with AIS were classified as: group I with mild rib cage deformity (n=88), group II with severe rib cage deformity (n=112) subgrouped into IIa (high gibbosity, n=48), IIb (high VSPI, n=48), and IIc (both high gibbosity and VSPI, n=16).Results: Groups IIa and IIb had a higher Cobb angle (33 vs. 54 degrees and 46 degrees, respectively) and torsion index (11 vs. 14 degrees and 13 degrees, respectively) than group I. Group IIb showed more severe hypokyphosis (IIb=21 degrees; IIa=33 degrees; I=36 degrees; control=42 degrees) with a reduced rib cage volume (IIb=4731 cm3; IIa=4985 cm3; I=5257 cm3; control=5254 cm3) and thickness (IIb=135 mm; IIa=148 mm; I=144 mm; control=144 mm). Group IIa showed an increasingly large local gibbosity descending from proximal to distal levels and did not follow the axial rotation of the spine. Group IIc showed characteristics of both groups IIa and IIb.Conclusions: This new classification of 3D rib cage deformity in AIS shows that the management of cases with high VSPI (groups IIb and IIc) should focus on restoring as much kyphosis as possible to avoid respiratory repercussions. Treatment indications in groups I and IIa would follow the consensual basic principles reported in the literature regarding bracing and surgery.

International audience; The aim of this work was to determine the feasibility of combined ultrasonography and elastography measurement to characterize the mechanical properties of the intercostal space during breathing. Eighteen asymptomatic participants (ages 13 ± 2 y) and six participants with adolescent idiopathic scoliosis (AIS) were included (Cobb angle 60° ± 12°). Ultrasonographic and elastographic clips were acquired of T8–T9 ribs and the intercostal space. The two adjacent ribs were tracked to infer the breathing cycle. Shear-wave speed (SWS) was measured in the intercostal space at different stages of the breathing cycle. SWS was symmetric in the control group, during both expiration and inspiration. In AIS, the SWS during inspiration was higher in the convex side than in the concave one (p = 0.02). Furthermore, SWS was higher during inspiration than expiration in the control group and in the AIS convex side, but not in the AIS concave side (p > 0.05). This new method combining echography and shear-wave elastography allowed measurement of the mechanical characteristics of the intercostal space at different phases of the breathing cycle and highlighted differences between the AIS and control groups. This approach opens the way to further analyses of the biomechanical characteristics of breathing in severe AIS.

The data collection was approved of by the ethical commit-tee (CPP 6001 Ile de France V), and patients and their parents signed an informed consent. Bracing is the most common treatment to stop the progression of adolescent idiopathic scoliosis. Finite element modeling could help improve brace design, but model validation is still a challenge. In this work, the clinical relevance of a predictive and subject-specific model for bracing was evaluated in forty-six AIS patients. The model reproduces brace action and the patient’s spinopelvic adjustments to keep balance. The model simulated 70% or more patients with geometrical parameters within a preselected tolerance level. Although the model simulation of the sagittal plane could be improved, the approach is promising for a realistic and predictive simulation of brace action. The authors are grateful to the ParisTech BiomecAM chair program on subject-specific musculoskeletal modelling (with the support of ParisTech and Yves Cotrel Foundations, Proteor, Société Génerale and Covea). We are also thankful to David Barrie Colridge for his support.

International audience; AbstractObjectives To determine lumbar intervertebral disc properties with shear wave elastography in adolescent idiopathic scoliotic(AIS) patients before and after surgery, and compare them with asymptomatic controls.Methods Twenty-five severe AIS patients with an indication for fusion surgery (15 ± 1.5 years old, the Cobb angle rangingbetween 40 and 93°) and fifty-nine asymptomatic adolescents (13 ± 2 years old) were included prospectively. Shear wave speed(SWS) was measured in the annulus fibrosus of L3-L4, L4-L5, and L5-S1 discs of each subject. In AIS patients, measurementstook place before surgery, and 3 months (N = 13) or 1 year after (N = 12).Results No difference was observed between disc levels in any group. When pooling disc levels, SWS was significantly higher inpreop AIS patients (4.0 ± 0.5 m/s) than in asymptomatic subjects (3.1 ± 0.5 m/s, p < 0.0001). SWS decreased 3 months postop(3.5 ± 0.3 m/s), and it decreased further towards normal values 1 year after (3.3 ± 0.4 m/s). SWS in preop AIS patients tended todecrease with the Cobb angle (Spearman’s rho = − 0.4, p = 0.05).Conclusion Shear wave elastography measurements showed that discs in AIS patients were altered relative to asymptomaticones, and this alteration tended to normalize 1 year post fusion surgery. Further studies should aim at determining if bracing ofmild scoliosis has an effect on disc properties.Key Points• Shear wave elastography shows alteration of annulus fibrosus in adolescent idiopathic scoliosis.• Disc elastography tends to normalize 1 year after surgery.

Purpose 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. Methods 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. Results AIS girls before 11 years of age had slightly longer spines than controls (p = 0.04, Mann–Whitney test). AIS verte- brae 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. Conclusion 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. The authors are grateful to the BiomecAM chair programme on subject-specific musculoskeletal modelling (with the support of ParisTech and Yves Cotrel Foundations, Société Générale, Covea and Proteor) and to the DHU MAMUTH for funding.

International audience; Purpose: To determine the short-term effect of bracing of adolescent idiopathic scoliotic (AIS) patients on the relationships between spinopelvic parameters related to balance, by comparing their in and out-of-brace geometry and versus healthy subjects. Methods: Forty-two AIS patients (Cobb angle 29° ± 12°, ranging from 16° to 61°) with a prescription of orthotic treatment were included retrospectively and prospectively. They all underwent biplanar radiography and 3D reconstruction of the spine and pelvis before bracing as well as less than 9 months after bracing. Eighty-three age-matched healthy adolescents were also included as control group and underwent biplanar radiography and 3D reconstruction. Results: Sacral slope was higher in AIS than healthy patients (p = 0.005). Bracing induced large changes of pelvic tilt (between - 9° and 9°), although patients' sagittal spinopelvic alignment tended to remain within the normality corridors defined by the healthy patients. Patients had flatter backs compared to healthy subjects and bracing further reduced their spinal curves. The head tended to remain above the pelvis in-brace. Conclusion: Analysis of sagittal alignment from head to pelvis showed that bracing further flattened the patients' backs and induced large compensating reorientations of the pelvis. Sagittal balance should be included in the planning and evaluation of brace treatment, since it could play a role in its outcome. These slides can be retrieved under Electronic Supplementary Material.

Various spinal and rib cage parameters measured from complex examinations were found to be correlated with preoperative pulmonary function tests (PFT). The aim was to investigate the relationship between preoperative rib cage parameters and PFT using biplanar stereoradiography in patients with severe adolescent idiopathic scoliosis. Fifty-four patients, 45 girls and nine boys, aged 13.8 ± 1.2 years, with Lenke 1 or 2 thoracic scoliosis (> 50°) requiring surgical correction were prospectively included. All patients underwent preoperative PFT and low-dose biplanar X-rays. The following data were collected: forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC ratio, residual volume, slow vital capacity (SVC), total lung capacity (TLC), rib cage volume (RCV), maximum rib hump, maximum width, mean thoracic index, spinal penetration index, apical vertebral rotation, main curve Cobb angle (MCCA), T4–T12 kyphosis. The primary outcome was the relationship between rib cage parameters and PFT. The secondary outcome was the relationship between rib cage parameters and spine parameters. Data were analyzed using Spearman’s rank test. A multivariable regression analysis was performed to compare PFTs and structural parameters. Significance was set at α = 0.05. The mean MCCA was 68.7° ± 16.7°. RCV was highly correlated with all pulmonary capacities: TLC (r = 0.76, p

The main function of the intervertebral disc is biomechanical function, since it must resist repetitive high loadings, while giving the spine its flexibility and protecting the spinal cord from over-straining. It partially owes its mechanical characteristics to the lamellar architecture of its outer layer, the annulus fibrosus. Today, no non-invasive means exist to characterize annulus lamellar structure in vivo. The aim of this work was to test the feasibility of imaging annulus fibrosus microstructure in vivo with ultrasonography. Twenty-nine healthy adolescents were included. Ultrasonographies of L3–L4 disc were acquired with a frontal approach. Annulus fibrosus was segmented in the images to measure the thickness of the lamellae. To validate lamellar appearance in ultrasonographies, multimodality images of two cow tail discs were compared: ultrasonography, magnetic resonance and optical microscopy. In vivo average lamellar thickness was 229.7 ± 91.5 μm, and it correlated with patient body mass index and age. Lamellar appearance in the three imaging modalities in vitro was consistent. Lamellar measurement uncertainty was 7%, with good agreement between two operators. Feasibility of ultrasonography for the analysis of lumbar annulus fibrosus structure was confirmed. Further work should aim at validating measurement reliability, and to assess the relevance of the method to characterize annulus alterations, for instance in disc degeneration or scoliosis. This study was funded by the ParisTech Biome- cAM chair programme on subject-specific musculoskeletal modelling (with the support of ParisTech and Yves Cotrel Foundations, Société Générale, and Covea), DHU MAMUTH, the Société Française de Chi- rurgie Orthopédique et Traumatologie (SOFCOT), the Devon Arthritis and Allied Reasearch Fund and the Henry Smith Charity. The authors are also grateful to Dr. Abdelmalek Benattayallah for his advice and technical support on MR imaging.

International audience; INTRODUCTION: Surgical site infection (SSI) following orthopedic surgery can have a substantial impact on patients and families. The rate remains high, ranging from 0.5% to 8.5% in pediatric spine surgery. It is common to allow children to bring a teddy bear (or similar toy) to the surgical ward to help reduce the stress of surgery. We hypothesize that despite their known benefits for children, teddies would increase the bacterial load in the surgical room.METHODS: A blinded descriptive study was conducted from June 2015 to September 2016. The study included children entering the hospital through the emergency ward for a traumatic cause requiring surgery. Patients admitted for infectious problems and those who had been hospitalized less than 6 months before the inclusion date were excluded. A picture of the teddy was taken and stored in a blind fashion. The AFNOR (Association française de normalisation) standardized rules for bacteriological surface control and the ISO/DIS 14698 protocol were strictly followed. Two independent observers performed blind bacteriologic analyses of the teddy bears with bacteria identification and colony counts. Photos of the teddy bears were then analyzed by two blinded, independent observers: one doctor and one parent from outside the hospital. Cleanliness and fluffiness of the toy was evaluated using a numeric scale.RESULTS: Bacteria were identified on 100% of the 53 teddies included. The mean number of bacteria was 182.5±49.8 CFU/25 cm2. Eight teddies (15.1%) tested positive for potential pathogenic bacteria (two staphylococcus aureus, one acinetobacter ursingii, four acinetobacter baumannii, one pseudomonas stutzeri). Three teddies (5.7%) tested positive for fungi. The median cleanliness score was 2 (interquartile range (IQR)=1) if rated by the doctor and 2 (IQR=1) if rated by the parent. No statistical difference was found between these two values in the global teddy bear population. We found no any statistical link between the number of CFUs and the cleanliness scores given by the doctor. The median fluffiness score given by the parent was 2 (IQR=1). Looking at the correlative CFUs, we found a statistically significant difference between each stage of fluffiness with a higher stage showing higher CFU (P

Background: Adolescent idiopathic scoliosis (AIS) can require surgical procedures that have major con-sequences. Coronal imbalance as assessed clinically using a plumb line is a key criterion for selecting patients to surgery. Nevertheless, the reference standard for assessing postural balance of the trunk is gravity line localisation within a validated frame of reference. Recent studies have established that the gravity line can be localised after body contour reconstruction from biplanar radiographs. The objec-tive of this study was to validate a gravity line localisation method based on biplanar radiographs in a population with AIS then to validate gravity line position versus plumb line position. Hypothesis: Plumb line and gravity line assessments of coronal balance correlate with each other. Material and methods: A gravity line localisation method based on biplanar radiography was validated in 14 patients with AIS versus force platform as the method of reference. Normal plumb line and gravity line positions were determined in 27 asymptomatic adolescents using biplanar radiography. The results of the two methods were then compared in 53 patients with AIS. Results: The reliability of gravity line localisation in the coronal plane based on biplanar radiography was 2.4 mm (95% confidence interval). The distance between the gravity line and the middle of the line connecting the centres of the two femoral heads (HA) showed a strongly significant association with plumb line position computed as the distance from the vertical line through the middle of T1 and the centre of the S1 endplate (T1V/S): r = 0.71, p < 0.0001. Of the 20 patients with plumb line results indicating coronal imbalance, 11 (55%) had a normal gravity line-to-HA distance. Of the 33 patients with normal plumb line results, 7 (21%) had an abnormal gravity line-to-HA distance. Conclusion: The results of this study validate gravity line determination from biplanar radiographs in a population with AIS. Plumb line position correlated significantly with gravity line position but was less accurate for guiding surgical decisions. Level of evidence: IV, retrospective study. Funding source SoFCOT grant to remunerate T. Hernandez during the year of research required for the project.

The primary goal of curve correction in neuromuscular patients is to restore coronal and sagittal trunk balance, including the pelvis, to maximize sitting balance. For several years, it has been a common practice to inject polymeric cement into osteoporotic bone through specially designed, perforated pedicle screws in an effort to enhance screw stability. Therefore, we started using the association of a spinopelvic fixation with S1 pedicle screw augmentation, using bisphenol-a-glycidyl dimethacrylate composite resin in neuromuscular patients with pelvic obliquity, technique in neuromuscular patients to improve pedicle screw stability of our pelvic construct. Ten patients undergoing spinopelvic fixation for a neuromuscular spinal deformity were enrolled in the study. Clinical and radiographic data were analyzed and presented. Minimal follow-up took place at 6 months to assess early complications. Five patients were diagnosed with spastic quadriplegia secondary to cerebral palsy, four had Duchenne’s muscular dystrophy, and one had a T5-level traumatic flaccid paraplegia. Preoperative PO ranged from 8° to 34° (mean 19.16°). Postoperative PO ranged from 0° to 6.3° (mean 1.6°). After surgery, all patients returned to a full-time sitting position between days 5 and 12 without the need for additional bracing. No mechanical failure of the construct was noted during follow-up. We used sacral pedicle screw augmentation as a reliable tool to strengthen spinopelvic fixation in neuromuscular scoliosis without increasing the intraoperative morbidity. In our practice, sacral screw augmentation can definitely enhance PO correction obtained by a posterior procedure.

OBJECT Spinopelvic alignment is crucial in assessing an energy-efficient posture in both normal and disease states, such as high-displacement developmental spondylolisthesis (HDDS). The overall effect in patients with HDDS who have undergone local surgical correction of lumbosacral imbalance for the global correction of spinal balance remains unclear. This paper reports the progressive spontaneous improvement of global sagittal balance following surgical correction of lumbosacral imbalance in patients with HDDS. METHODS The records of 15 patients with HDDS who underwent surgery between 2005 and 2010 were reviewed. The treatment consisted of L4–sacrum reduction and fusion via a posterior approach, resulting in complete correction of lumbosacral kyphosis. Preoperative, 6-month postoperative, and final follow-up postoperative angular measurements were taken from full-spine lateral radiographs obtained with the patient in a standard standing position. Radiographic measurements included pelvic incidence, sacral slope, lumbar lordosis, and thoracic kyphosis. The degree of lumbosacral kyphosis was evaluated by the lumbosacral angle. Because of the small number of patients, nonparametric tests were considered for data analysis. RESULTS Preoperative lumbosacral kyphosis and L-5 anterior slip were corrected by instrumentation. Transient neurological complications were noted in 5 patients. Statistical analysis showed a significant increase of thoracic kyphosis on 6-month postoperative and final follow-up radiographs (p < 0.001). A statistically significant decrease of lumbar lordosis was noted between preoperative and 6-month control radiographs (p < 0.001) and between preoperative and final follow-up radiographs (p < 0.001). CONCLUSIONS Based on the authors' observations, this technique resulted in an effective reduction of L-5 anterior slip and significant reduction of lumbosacral kyphosis (from 69.8° to 105.13°). Due to complete reduction of lumbosacral kyphosis and anterior trunk displacement associated with L-5 anterior slipping, lumbar lordosis progressively decreased and thoracic kyphosis progressively increased postoperatively. Adjusting the sagittal trunk balance produced not only pelvic anteversion, but also reciprocal adjustment of lumbar lordosis and thoracic kyphosis, creating a satisfactory level of compensated global sagittal balance.