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The broadening of atomic emission lines by high-velocity motion of gas near accreting supermassive black holes is an observational hallmark of quasars 1 . Observations of broad emission lines could potentially constrain the mechanism for transporting gas inwards through accretion disks or outwards through winds 2 . The size of regions for which broad emission lines are observed (broad-line regions) has been estimated by measuring the delay in light travel time between the variable brightness of the accretion disk  continuum and the emission lines 3 —a method known as reverberation mapping. In some models the emission lines arise from a continuous outflow 4 , whereas in others they arise from orbiting gas clouds 5 . Directly imaging such regions has not hitherto been possible because of their small angular size (less than 10 −4 arcseconds 3 , 6 ). Here we report a spatial offset (with a spatial resolution of 10 −5 arcseconds, or about 0.03 parsecs for a distance of 550 million parsecs) between the red and blue photo-centres of the broad Paschen-α line of the quasar 3C 273 perpendicular to the direction of its radio jet. This spatial offset corresponds to a gradient in the velocity of the gas and thus implies that the gas is orbiting the central supermassive black hole. The data are well fitted by a broad-line-region model of a thick disk of gravitationally bound material orbiting a black hole of 3 × 10 8 solar masses. We infer a disk radius of 150 light days; a radius of 100–400 light days was found previously using reverberation mapping 7 – 9 . The rotation axis of the disk aligns in inclination and position angle with the radio jet. Our results support the methods that are often used to estimate the masses of accreting supermassive black holes and to study their evolution over cosmic time. High-angular-resolution observations of the quasar 3C 273 reveal that it has a relatively small but thick disk, viewed nearly face-on, in which material is orbiting the central supermassive black hole.

BackgroundPrior reports suggest that osteoarticular infections may be increasing over time.Questions/PurposesWe sought to determine if incidence rates, median in-hospital costs, and length of stay (LOS) of osteomyelitis, septic arthritis (SA), and combined infections have changed over time for pediatric patients, and how they compare to previously reported rates.MethodsThe Kids’ Inpatient Database (KID), a US national sample of pediatric hospital discharge records from 1997, 2000, 2003, 2006, 2009, and 2012, was used to determine yearly estimated counts of infections in children 20 years of age or younger. US census data was used to calculate yearly incidence rates. Trend tests using linear contrast analysis were used to compare estimated median LOS and inflation-adjusted median costs over time for each type of infection.ResultsFrom 1997 through 2012, the incidence rate of osteomyelitis increased from 7.9 to 10.5 per 100,000, SA was unchanged from 5.3 to 5.2 per 100, and combined infections increased from 0.8 to 1.3 per 100,000. Median LOS from 1997 to 2012 showed no significant change for osteomyelitis (5.0 to 4.9 days), SA (4.4 to 4.1 days), or combined infections (6.5 to 6.8 days). Median in-hospital costs from 1997 to 2012 increased for osteomyelitis ($7735 to $11,823), SA ($5041 to $10,574), and combined infections ($12,691 to $16,260).ConclusionIn pediatric patients, the estimated incidence rate of SA appeared stable, while rates of osteomyelitis and combined infections increased. These estimated rates fall within previously reported ranges. Despite stable LOS, costs have increased over time.

Abstract Purpose Scoliosis, chest wall deformities and pulmonary involvement are common features of Marfan syndrome (MFS). We aimed to assess the impact of spinal and chest wall deformities on pulmonary function in paediatric MFS patients with a surgically managed spinal deformity. Methods In this multicentre retrospective study, spirometry, lung volumes and radiographic imaging were performed on 26 MFS patients between the ages of seven and 18 years who were undergoing planned spinal fusion surgery for spinal deformity. A correlation analysis assessed the relationship between radiographic measurements of spinal and chest wall deformities and predicted total lung capacity (TLC), forced vital capacity (FVC) and the ratio between forced expiratory volume in one second and FVC (FEV1/FVC). Results In total, 18 patients (70%) had impaired pulmonary function. Thoracic kyphosis (mean 19.3°; -32° to 54°) had a strong positive correlation with FEV1/FVC (r = 0.65; p < 0.001). Significant decrease in FEV1/FVC below 80% occurred at kyphosis under 15° (p = 0.004). Kyphosis had a moderate negative correlation with FVC (r = -0.43; p = 0.03). Chest wall deformity had a strong negative correlation with FEV1/FVC (r = -0.61; p = 0.001). The magnitude of the thoracic curve (mean 55.2°; 28° to 92°) had a significant moderate negative correlation with TLC (r = -0.45; p = 0.04). Conclusion In MFS, three factors correlate with decreased pulmonary function measures: hypokyphosis, increasing chest wall deformity and increasing coronal curve magnitude. Hypokyphosis and increased chest wall deformity correlated with diminished FEV1/FVC; increasing thoracic spinal curvature with diminished TLC. Further analysis with a larger cohort will help better define the relationship between these deformities and pulmonary function in this unique population. Level of Evidence IV

Background: Adolescent idiopathic scoliosis results in three dimensional changes to a patient’s body, which may change a patient’s range of motion. Surface topography is an emerging technology to evaluate three dimensional parameters in patients with scoliosis. The goal of this paper is to introduce novel and reliable surface topographic measurements for the assessment of global coronal and sagittal range of motion of the spine in adolescents, and to determine if these measurements can distinguish between adolescents with lumbar scoliosis and those without scoliosis. Methods: This study is a retrospective cohort study of a prospectively collected registry. Using a surface topographic scanner, a finger to floor and lateral bending scans were performed on each subject. Inter- and intra-rater reliabilities were assessed for each measurement. ANOVA analysis was used to test comparative hypotheses. Results: Inter-rater reliability for lateral bending fingertip asymmetry (LBFA) and lateral bending acromia asymmetry (LBAA) displayed poor reliability, while the coronal angle asymmetry (CAA), coronal angle range of motion (CAR), forward bending finger to floor (FBFF), forward bending acromia to floor (FBAF), sagittal angle (SA), and sagittal angle normalized (SAN) demonstrated good to excellent reliability. There was a significant difference between controls and lumbar scoliosis patients for LBFA, LBAA, CAA and FBAF (p-values < 0.01). Conclusion: Surface topography yields a reliable and rapid process for measuring global spine range of motion in the coronal and sagittal planes. Using these tools, there was a significant difference in measurements between patients with lumbar scoliosis and controls. In the future, we hope to be able to assess and predict perioperative spinal mobility changes.

Axial twisting of the spine has been previously shown to be affected by scoliosis with decreased motion and asymmetric twisting. Existing methods for evaluating twisting may be cumbersome, unreliable, or require radiation exposure. In this study, we present an automated surface topographic measurement tool to evaluate global axial rotation of the spine, along with two measurements: twisting range of motion (TROM) and twisting asymmetry index (TASI). The aim of this study is to evaluate the impact of scoliosis on axial range of motion. Adolescent idiopathic scoliosis (AIS) patients and asymptomatic controls were scanned in a topographic scanner while twisting maximally to the left and right. TROM was significantly lower for AIS patients compared to control patients (69.1° vs. 78.5°, p = 0.020). TASI was significantly higher for AIS patients compared to control patients (29.6 vs. 19.8, p = 0.023). After stratifying by scoliosis severity, both TROM and TASI were significantly different only between control and severe scoliosis patients (Cobb angle > 40°). AIS patients were then divided by their major curve region (thoracic, thoracolumbar, or lumbar). ANOVA and post hoc tests showed that only TROM is significantly different between thoracic AIS patients and control patients. Thus, we demonstrate that surface topographic scanning can be used to evaluate twisting in AIS patients.

Purpose Adolescent idiopathic scoliosis (AIS) patients experience structural spinal deformity, but the impact of AIS on physical activity is not widely studied. Reports of physical activity levels between children with AIS and their peers are mixed. This study sought to characterize the relationship between spinal deformity, spinal range of motion, and self-reported physical activity in AIS patients. Methods Patients aged 11–21 completed self-reported measures of physical activity using the HSS Pedi-FABS and PROMIS Physical Activity questionnaires. Radiographic measures were obtained from standing biplanar radiographic imaging. Surface topographic (ST) imaging data was obtained using a whole-body ST scanning system. Hierarchical linear regression models analyzed the relationship between physical activity, ST, and radiographic deformity while controlling for age and BMI. Results 149 patients with AIS (mean age 14.5 ± 2.0 years, mean Cobb angle 39.7° ± 18.9°) were included. In the hierarchical regression predicting physical activity from Cobb angle, no factors were significant predictors of physical activity. When predicting physical activity from ST ROM measurements, age and BMI served as covariates. No covariates or ST ROM measurements were significant predictors of physical activity levels for either activity measure. Conclusions Physical activity levels of patients with AIS were not predicted by levels of radiographic deformity or surface topographic range of motion. Although patients may experience severe structural deformity and range of motion limitations, these factors do not appear to be associated with decreased physical activity level utilizing validated patient activity questionnaires. Level of evidence Level II.

Background: Back pain is a common condition that affects millions of Americans each year, including both adult and pediatric populations. To our knowledge, there has been no study that has epidemiologically studied back pain in a representative cohort of American children and adolescents. The purpose of this study was to establish the prevalence of back pain in American children and adolescents 10-18 years old and investigate for any demographic or physical activity predictors of increased risk. Methods: A cross-sectional survey-based investigation was performed in 2,001 children and adolescents, equally split by age and sex, and representing census-weighted distributions of state of residence, race/ethnicity, and health insurance status. Overall prevalence of back pain (at present and any time in past year) was calculated, and comparative analyses were performed to investigate any relationship between back pain and age, sex, backpack use, race/ethnicity, BMI, insurance status, and level of activity. Results: Two thousand and one subjects completed the survey of which 1,000 were male (50%) and 1,001 were female (50%). The mean age of the respondents was 14.0±2.6 years and the mean BMI was 22.4±8.1. A majority of subjects (1,633; 81.6%) stated that they participated in a sport or physical activity, with basketball being the most common sport followed by soccer, baseball, dance, and football. In total, 743 subjects (37.1%) stated that they had back pain within the last year, most commonly in the lumbar region (64.9%). The mean age of the subjects with back pain was significantly higher than those who did not experience back pain in the previous year (14.76±2.4 vs. 13.6±2.6 years old, P<0.001). Regression analysis demonstrated that the proportion of subjects who experienced back pain within the previous year increased linearly by age from 10 to 16 years old before plateauing just under 50% from age 16 to 18 (Figure 1). Age accounted for 94% of the variation of the response data for back pain in the past year, and 84% for those currently experiencing back pain (P<0.001 for both). Subjects with back pain had greater BMI than those without back pain (23.5±9.5 vs. 21.8±7.0, P<0.001). Subjects that used backpacks with two straps were least likely to have back pain (33.0%), while those who used rolling backpacks (57.1%), backpacks with two straps and the waistband fastened (55.9%), and backpacks with one strap (46.9%) were more likely to have back pain (P<0.05 for all). Females were more likely to have had back pain than males in the previous year (41.5% vs. 32.8%, P<0.001). Varsity and national/internationally competitive athletes demonstrated the highest rate of back pain in the previous year (51.0% and 49.2%, respectively). This was significantly higher than the prevalence of back pain in recreational, local/community, and junior varsity athletes (33.5%, 29.7%, 44.4%, respectively, P<0.05 for all pairwise comparisons). No associations were found between subjects’ health insurance status or race/ethnicity and occurrence of back pain. Conclusions/Significance: The current study quantifies the prevalence of back pain in an epidemiologic, census-derived sample of 2,001 American children and adolescents. There was a statistically significant linear increase by age from 10 to 16 years old before plateauing just under 50% from age 16 to 18. Additional statistically significant associations between presence of back pain in the previous year and BMI, backpack use, sex, and level of athletic participation were discovered. No association between insurance status or race and back pain was reported. These results will aid in future research and clinical care by demonstrating the epidemiology of back pain within the 10-18 year old American pediatric population. Figure Legend: Figure 1. Percent of sample (N=2,001 American youth) with back pain in the previous year (blue line, diamonds) and currently (red line, squares) by age. There was a linear increase from the ages of 10 to 16 before plateauing just under 50% at 16 years old.

Background:The prevalence of intraspinal pathology associated with scoliosis has been reported to be as high as 26% in some series, and, on the basis of this finding, preoperative magnetic resonance imaging is used in the screening of patients with adolescent idiopathic scoliosis. However, this practice continues to be highly controversial. In order to better resolve this issue, we performed what we believe to be the largest prospective study to evaluate the need for preoperative magnetic resonance imaging in patients with adolescent idiopathic scoliosis requiring arthrodesis of the spine.Methods:A total of 327 consecutive patients with adolescent idiopathic scoliosis were evaluated between December 1991 and March 1999. All patients in the study presented with an adolescent idiopathic scoliosis curve pattern and had a complete physical and neurologic examination. Magnetic resonance imaging of the brain and the spinal cord were performed as part of their preoperative work-up.Results:Seven patients had an abnormality noted on magnetic resonance imaging. These abnormalities included a spinal cord syrinx in two patients (0.6%) and an Arnold-Chiari type-I malformation in four (1.2%). One patient had an abnormal fatty infiltration of the tenth thoracic vertebral body. No patient required neurosurgical intervention or additional work-up. All patients who underwent spinal arthrodesis with segmental instrumentation tolerated the surgery without any immediate or delayed neurologic sequelae.Conclusions:The fact that magnetic resonance imaging did not detect any important pathology in the large number of patients in this study strongly suggests that magnetic resonance imaging is not indicated prior to arthrodesis of the spine in patients with an adolescent idiopathic scoliosis curve pattern and a normal physical and neurologic examination.

Pelvic fixation is commonly used in correcting pelvic obliquity in pediatric patients with neuromuscular scoliosis and in preserving stability in adult patients with lumbosacral spondylolisthesis or instances of traumatic or osteoporotic fracture. S2-alar-iliac screws are commonly used in this role and have been proposed to reduce implant prominence when compared to traditional pelvic fusion utilizing iliac screws. The aim of this technical note is to describe a technique for robotically navigated placement of S2-alar-iliac screws in pediatric patients with neuromuscular scoliosis, which (a) minimizes the significant exposure needed to identify a bony start point, (b) aids in instrumenting the irregular anatomy often found in patients with neuromuscular scoliosis, and (c) allows for greater precision than traditional open or fluoroscopic techniques. We present five cases that underwent posterior spinal fusion to the pelvis with this technique that demonstrate the safety and efficacy of this procedure.