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Reformatted coronal CT images of idiopathic scoliosis patients, used for supine Cobb angle measurements.

Reformatted coronal CT images of idiopathic scoliosis patients, used for supine Cobb angle measurements.

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Background Supine imaging modalities provide valuable 3D information on scoliotic anatomy, but the altered spine geometry between the supine and standing positions affects the Cobb angle measurement. Previous studies report a mean 7°-10° Cobb angle increase from supine to standing, but none have reported the effect of endplate pre-selection or whet...

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... the re- formatted coronal slices into a single image was per- formed using the z-project function in ImageJ. Figure 1 shows example of the reformatted coronal images ob- tained using this technique. A hardcopy of each re- formatted coronal CT image was printed onto an A4 sheet of paper at a scale of approximately 60%, to allow each observer to measure the Cobb angle using the standard Cobb method. ...

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... Brink et al. reported a significant correlation of the morphology of the scoliotic spine in all three planes between standard upright X-ray, MRI, and CT scan [13]. Keenan et al. showed 2014 that there is a statistically significant relationship between the Cobb angle in supine and upright position for the major curve [14]. However, minor curves were not analyzed, especially not regarding to the flexibility. ...
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Purpose There is no data that show if it is possible to determine if a curve is structural or non-structural or to assess flexibility of an adolescent idiopathic scoliosis (AIS) by recumbent images like a CT scan (CTS) instead of bending radiographs (BR). We investigated if the results of BR may be compared to those of CTS. Methods We retrospectively analyzed prospectively collected data of patients with AIS in whom a selective spinal fusion was performed and in whom a CTS, BR, and full spine x-rays were made preoperatively. We measured the Cobb angles of the main and the minor curve in full spine x-ray, BR, and CTS. Results After applying inclusion and exclusion criteria, 39 patients were included. We found a strong correlation ( r = 0.806, p < 0.01) between the Cobb angle of the main curve in BR and the Cobb angle of the main curve in the CTS and between the Cobb angle of the minor curve in BR and the Cobb angle of the minor curve in the CTS ( r = 0.601, p < 0.01). All patients with a minor curve of less than 25 degrees in the BR had a Cobb angle of less than 35 degrees in the CTS. Conclusion Spinal curves showed a significant correlation between bending radiographs and recumbent images (CTS). In our group of patients, a Cobb angle of the minor curve of less than 35 degrees in the CTS indicated that this minor curve was non-structural.
... MRI may be arguably the most useful modality in future research, allowing for radiation-free longitudinal diagnostic monitoring of AIS development and segmental changes. Despite being limited by supine positioning, there has been recent demonstration that a linear association between supine coronal curve measurements and standing radiographic measurement of AIS major thoracic curve angle exists [76,77]. One author has confirmed the feasibility and reliability of upright MRI to diagnose and evaluate AIS, but such equipment is rarely available to either clinicians or researchers [78]. ...
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PurposeThere has been a recent shift toward the analysis of the pathoanatomical variation of the adolescent idiopathic scoliosis (AIS) spine with the three dimensions, and research of level-wise vertebral body morphology in single anatomical planes is now replete within the field. In addition to providing a precise description of the osseous structures that are the focus of instrumented surgical interventions, understanding the anatomical variation between vertebral bodies will elucidate possible pathoaetiological mechanisms of the onset of scoliotic deformity.Methods This review aimed to discuss the current landscape of AIS segmental vertebral morphology research and provide a comprehensive report of the typical patterns observed at the individual vertebral level.ResultsWe have detailed how these vertebrae are typically characterised by lateral wedging to the convexity, have a marked degree of anterior overgrowth, are rotated towards the convexity, have inherent gyratory mechanical torsion created within them and are associated with pedicles on the concave side being narrower, longer and more laterally angled. For the most part, these findings are most pronounced at and around the apex of a scoliotic curve, with these deformations reducing towards junctional vertebrae. We have also summarised a nomenclature defined by the Scoliosis Research Society, highlighting the need for more consistent reporting of these level-wise dimensional anatomical changes.Conclusion Finally, we emphasised how a marked degree of heterogeneity exists between the included investigations, namely in scoliotic curve-type inclusion, imaging modality and timepoint of analysis within scoliosis’ longitudinal development, and how improvement in these study design characteristics will enhance ongoing research.
... Supine, supine traction, and sitting push-up positions have been used as substitutes, although there is no general consensus validating if these positions correlate with the sitting position [1]. Earlier studies of patients with idiopathic scoliosis investigated the correlation of the Cobb angle with position changes by comparing radiographic images taken with the patient upright position to those taken with the patient supine [4][5][6][7][8][9]. However, no literature to our knowledge has addressed the impact of change in position on the Cobb angle measurement within a population of non-ambulatory children with myelodysplasia. ...
... The Cobb angle method is the most commonly used method for evaluating curve magnitude and severity in all types of scoliosis [2]. Previous studies on patients with idiopathic scoliosis evaluating the effect that the change of position has on the magnitude of the Cobb angle demonstrated a mean difference of 7° to 11° (comparing standing and supine positions) [4][5][6][7][8][9]. These findings are caused by the varying effects of the gravitational load on the patients' spine with each position. ...
... This difference in the measurement of the coronal Cobb angle secondary to position change may have a negative effect on clinical decision making if it is not accounted for in the clinician's evaluation of progression of the scoliosis. In this study, we found that the mean Cobb angles measured with the patient sitting were significantly greater than those with the patient in the sitting push-up, supine, and supine traction positions, which likely is secondary to the effects of gravitational loading as noted in previous studies [4][5][6]. The data demonstrate that the mean difference in thoracic Cobb angle measurements between sitting and all the other positions ranged from 6° to 12°. ...
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Objective: The purpose of this study was to assess the impact of patient position on the magnitude of the coronal Cobb angle measurements in relation to the change of position using plain radiograph on non-ambulatory children with myelodysplasia. Whole-spine radiographs with the patient sitting generally are preferred for the diagnosis and monitoring of progression of scoliosis in neuromuscular patients. Supine, supine traction, and sitting push-up positions have been used as substitutes, although there is no general consensus validating if these positions correlate with the sitting position. The magnitude of the Cobb angles in neuromuscular scoliosis may vary greatly depending on the position of the patient. Methods: Radiographs of 39 myelodysplastic, non-ambulatory children were evaluated to assess the impact of change in positions (unsupported sitting, sitting push-up, supine, and supine traction) on coronal Cobb angle measurement using plain whole-spine radiographs. Results: The mean difference in thoracic Cobb angle measurements between sitting and all other positions ranged from 6° to 12°. At the lumbar level, the Cobb angles ranged from 12° to 16°. Conclusions: Statistically significant differences in the Cobb angle measurements were identified between plain radiographs of the whole spine with the patient in the unsupported sitting position compared to sitting push-up, supine, and supine traction positions. The data support that the magnitude of the Cobb angles in neuromuscular scoliosis varies greatly depending on the position of the patient. Level of evidence: III.
... Therefore, to understand the pathology of the whole spine, it is important to determine the difference in the curve measurement between the supine and standing positions, including alignment. A drawback of previous reports is the potential error related to different measurement methods used for X-ray and other imaging modalities (CT or MRI) to compare the Cobb angle, which may lead to misinterpretation or controversy [1,20,21,28,30]. ...
... The difference in curve magnitude between standing and supine positions was studied previously in AIS patients. Keenan et al. [20] investigated the difference in the Cobb angle between the supine position (reconstructed CT) and standing position (conventional X-ray) in 52 patients with AIS having a mean age of 14.6 years. They reported a mean Cobb angle on standing radiographs of 51.9°, which was a significantly greater value than the mean Cobb angle on supine CT images of 40.5° [20]. ...
... Keenan et al. [20] investigated the difference in the Cobb angle between the supine position (reconstructed CT) and standing position (conventional X-ray) in 52 patients with AIS having a mean age of 14.6 years. They reported a mean Cobb angle on standing radiographs of 51.9°, which was a significantly greater value than the mean Cobb angle on supine CT images of 40.5° [20]. The Cobb angle measurement, however, includes a fundamental error related to the selection of the vertebral endplates. ...
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Background A precise comparison of supine and standing whole spine alignment in both the coronal and sagittal planes, including the pelvic parameters, has not been reported. Furthermore, previous studies investigated positional differences in the Cobb angle only in young patients with idiopathic scoliosis. The difference in alignment has never been investigated in a population of patients with adult spinal deformity (ASD). In most cases, ASD patients are aware of the symptoms when standing and tend to stoop with back pain, whereas the symptoms disappear when lying on a bed. Therefore, it is important to elucidate the positional differences in the deformity in older adults. The purposes of this study are to establish a method for comparing whole spine alignment between supine and standing, and to clarify the positional difference of the alignment in the patients with ASD. Methods Twenty-four patients with ASD (mean age: 60.1 years, range 20–80 years; 24 women) were evaluated. A slot-scanning three-dimensional X-ray imager (EOS) was used to assess the whole spine in the standing position. Computed tomography was used to assess the whole spine in the supine position. The computed tomography DICOM dataset of the whole spine in the supine position was transformed to two-dimensional (coronal and sagittal) digital reconstructed radiography images. The digital reconstructed radiography images were input for three-dimensional measurement by the EOS software and compared with the standing whole spine alignment measured by EOS. Results The mean intraclass correlation coefficients (supine, standing) of intra-rater / inter-rater reliabilities for the measured parameters were 0.981, 0.984 / 0.970, 0.986, respectively. The Cobb and rotation angles of the major curve, mostly the thoracolumbar area, were significantly greater in the standing position than in the supine position. Lumbar lordosis during standing was significantly kyphotic. With respect to the pelvic parameters, the sacral slope was significantly smaller in the standing position than in the supine position. Pelvic tilt and pelvic incidence were significantly greater in the standing position than in the supine position. Conclusions The lumbar to pelvic parameters and the major curve in standing position significantly deteriorate compared with the supine position in patients with ASD.
... The same levels were used for each patient on the three different imaging methods. Cobb end vertebrae were selected on the radiographs and applied to the other imaging modalities [14]. For measurement of apical rotation on the MRI and CT scans, complete 3-D reconstructions were acquired using semi-automatic analysis software (ScoliosisAnalysis 4.1, Imaging Division, Utrecht, The Netherlands) and a previously validated imaging method [15]. ...
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Background Patients with adolescent idiopathic scoliosis (AIS) are usually investigated by serial imaging studies during the course of treatment, some imaging involves ionizing radiation, and the radiation doses are cumulative. Few studies have addressed the correlation of spinal deformity captured by these different imaging modalities, for which patient positioning are different. To the best of our knowledge, this is the first study to compare the coronal, axial, and sagittal morphology of the scoliotic spine in three different body positions (upright, prone, and supine) and between three different imaging modalities (X-ray, CT, and MRI). Methods Sixty-two AIS patients scheduled for scoliosis surgery, and having undergone standard pre-operative work-up, were included. This work-up included upright full-spine radiographs, supine bending radiographs, supine MRI, and prone CT as is the routine in one of our institutions. In all three positions, Cobb angles, thoracic kyphosis (TK), lumbar lordosis (LL), and vertebral rotation were determined. The relationship among three positions (upright X-ray, prone CT, and supine MRI) was investigated according to the Bland-Altman test, whereas the correlation was described by the intraclass correlation coefficient (ICC). ResultsThoracic and lumbar Cobb angles correlated significantly between conventional radiographs (68° ± 15° and 44° ± 17°), prone CT (54° ± 15° and 33° ± 15°), and supine MRI (57° ± 14° and 35° ± 16°; ICC ≥0.96; P < 0.001). The thoracic and lumbar apical vertebral rotation showed a good correlation among three positions (upright, 22° ± 12° and 11° ± 13°; prone, 20° ± 9° and 8° ± 11°; supine, 16° ± 11° and 6° ± 14°; ICC ≥0.82; P < 0.001). The TK and LL correlated well among three different positions (TK 26° ± 11°, 22° ± 12°, and 17° ± 10°; P ≤ 0.004; LL 49° ± 12°, 45° ± 11°, and 44° ± 12°; P < 0.006; ICC 0.87 and 0.85). Conclusions Although there is a generalized underestimation of morphological parameters of the scoliotic deformity in the supine and prone positions as compared to the upright position, a significant correlation of these parameters is still evident among different body positions by different imaging modalities. Findings of this study suggest that severity of scoliotic deformity in AIS patients can be largely represented by different imaging modalities despite the difference in body positioning.
... The rib hump was measured using a simple Scoliometer [28][29][30] or smartphone [31] with the patient in the forward bending position before surgery and at 6 and 24 months after surgery. Cobb angles were measured on the available standing PA radiographs (before surgery and 6 months after surgery) and on reformatted coronal plane images produced from the 6 to 24 months postsurgery CT scan data using a method that has been described previously [19,24,32,33]. Whilst it is known that the Cobb angle is reduced in supine compared to standing [34,35], a valid comparison of changes between 6 and 24 months could be made using the supine CT data at these time points during the post-operative period. ...
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Background: Axial vertebral rotation is a key characteristic of adolescent idiopathic scoliosis (AIS), and its reduction is one of the goals of corrective surgery. Recurrence of deformity after surgical correction may relate to rotation changes that occur in the anterior vertebral column after surgery, but whether any change occurs within the fused segment or in adjacent unfused levels following thoracoscopic anterior spinal fusion (TASF) is unknown. An analysis of measurements from an existing postoperative CT dataset was performed to investigate the occurrence of inter- and intra-vertebral rotation changes after TASF within and adjacent to the fused spinal segment and look for any relationships with the Cobb angle and rib hump in the two years after surgery. Methods: 39 Lenke Type 1 main thoracic patients underwent TASF for progressive AIS and low dose computed tomography scanning of the instrumented levels of the spine at 6 and 24 months after surgery. Vertebral rotation was measured at the superior and inferior endplates on true axial images for all vertebral levels in the fused segment plus one adjacent level cranially and caudally. Intra-observer variability for rotation measurements was assessed using 95% limits of agreement to detect significant changes in inter/intra-vertebral rotation. Results: Significant local changes in inter- and intra-vertebral rotation were found to have occurred between 6 and 24 months after anterior surgical fusion within the fused spinal segment, albeit with no consistent pattern of location or direction within the instrumented fusion construct. No significant en-bloc movement of the entire fused spinal segment relative to the adjacent un-instrumented cranial and caudal intervertebral levels was found. No clear correlation was found between any vertebral rotation changes and Cobb angle or rib hump measures. Conclusions: Localised inter- and intra-vertebral rotation occurs between 6 and 24 months after TASF, both within the instrumented spinal segments and in the adjacent un-instrumented levels of the adolescent spine. The lack of measurable en-bloc movement of the fused segment relative to the adjacent un-instrumented levels suggests that overall stability of the instrumented construct is achieved, however the vertebrae within the fusion mass continue to adapt and remodel, resulting in ongoing local anatomical and biomechanical changes in the adolescent spine.
... In an attempt to propose a new classification based on threedimensional modeling of the spine, quantifying the structural nature of a curve is pivotal to integrate flexibility characteristics within the classification paradigm, such as in the Lenke classification. Cobb angle deviations or methods estimating fulcrum flexibility can be considered a potential alternative measure of spinal flexibility [23]. A limitation of the present study is that curve flexibility was not integrated into the auto-encoding process. ...
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Purpose The classification of three-dimensional (3D) spinal deformities remains an open question in adolescent idiopathic scoliosis. Recent studies have investigated pattern classification based on explicit clinical parameters. An emerging trend however seeks to simplify complex spine geometries and capture the predominant modes of variability of the deformation. The objective of this study is to perform a 3D characterization and morphology analysis of the thoracic and thoraco/lumbar scoliotic spines (cross-sectional study). The presence of subgroups within all Lenke types will be investigated by analyzing a simplified representation of the geometric 3D reconstruction of a patient’s spine, and to establish the basis for a new classification approach based on a machine learning algorithm. Methods Three-dimensional reconstructions of coronal and sagittal standing radiographs of 663 patients, for a total of 915 visits, covering all types of deformities in adolescent idiopathic scoliosis (single, double and triple curves) and reviewed by the 3D Classification Committee of the Scoliosis Research Society, were analyzed using a machine learning algorithm based on stacked auto-encoders. The codes produced for each 3D reconstruction would be then grouped together using an unsupervised clustering method. For each identified cluster, Cobb angle and orientation of the plane of maximum curvature in the thoracic and lumbar curves, axial rotation of the apical vertebrae, kyphosis (T4–T12), lordosis (L1–S1) and pelvic incidence were obtained. No assumptions were made regarding grouping tendencies in the data nor were the number of clusters predefined. Results Eleven groups were revealed from the 915 visits, wherein the location of the main curve, kyphosis and lordosis were the three major discriminating factors with slight overlap between groups. Two main groups emerge among the eleven different clusters of patients: a first with small thoracic deformities and large lumbar deformities, while the other with large thoracic deformities and small lumbar curvature. The main factor that allowed identifying eleven distinct subgroups within the surgical patients (major curves) from Lenke type-1 to type-6 curves, was the location of the apical vertebra as identified by the planes of maximum curvature obtained in both thoracic and thoraco/lumbar segments. Both hypokyphotic and hyperkypothic clusters were primarily composed of Lenke 1–4 curve type patients, while a hyperlordotic cluster was composed of Lenke 5 and 6 curve type patients. Conclusion The stacked auto-encoder analysis technique helped to simplify the complex nature of 3D spine models, while preserving the intrinsic properties that are typically measured with explicit parameters derived from the 3D reconstruction.
... The same levels were used for each patient on the three different imaging methods. Cobb end vertebrae were selected on the radiographs and applied to the other imaging modalities [14]. For measurement of apical rotation on the MRI and CT scans, complete 3-D reconstructions were acquired using semi-automatic analysis software (ScoliosisAnalysis 4.1, Imaging Division, Utrecht, The Netherlands) and a previously validated imaging method [15]. ...
... Because the foregoing analysis was performed on supine CT anatomy, we also include an estimated correction for supine to standing change in Cobb angle (grey bars in Fig. 4). This correction was performed by measuring the Cobb angle on both the supine CT image and the clinical standing X-ray as described in a previous study [23]. The difference between the two Cobb angle measures was divided by the patient's supine Cobb angle, and used to scale the joint moment at the apex to provide an estimate of the joint moment in standing. ...
... Because the CT scans were performed in the supine position and Cobb angle magnitudes in this position are known to be 7-10°smaller than those measured in standing [23,24], the joint moments in actual standing (as opposed to the simulated standing analysis performed here) would be expected to be greater than those calculated. The effect of the supine vs standing position on joint moments was estimated in Fig. 4, with the apical joint moment increasing by an average of 1.08 Nm (range 0.43-2.34 ...
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Background: Adolescent Idiopathic Scoliosis is the most common type of spinal deformity, and whilst the isk of progression appears to be biomechanically mediated (larger deformities are more likely to progress), the detailed biomechanical mechanisms driving progression are not well understood. Gravitational forces in the upright position are the primary sustained loads experienced by the spine. In scoliosis they are asymmetrical, generating moments about the spinal joints which may promote asymmetrical growth and deformity progression. Using 3D imaging modalities to estimate segmental torso masses allows the gravitational loading on the scoliotic spine to be determined. The resulting distribution of joint moments aids understanding of the mechanics of scoliosis progression. Methods: Existing low-dose CT scans were used to estimate torso segment masses and joint moments for 20 female scoliosis patients. Intervertebral joint moments at each vertebral level were found by summing the moments of each of the torso segment masses above the required joint. Results: The patients' mean age was 15.3 years (SD 2.3; range 11.9-22.3 years); mean thoracic major Cobb angle 52(°) (SD 5.9(°); range 42-63(°)) and mean weight 57.5 kg (SD 11.5 kg; range 41-84.7 kg). Joint moments of up to 7 Nm were estimated at the apical level. No significant correlation was found between the patients' major Cobb angles and apical joint moments. Conclusions: Patients with larger Cobb angles do not necessarily have higher joint moments, and curve shape is an important determinant of joint moment distribution. These findings may help to explain the variations in progression between individual patients. This study suggests that substantial corrective forces are required of either internal instrumentation or orthoses to effectively counter the gravity-induced moments acting to deform the spinal joints of idiopathic scoliosis patients.
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Purpose. This study aimed to investigate the efficacy of spinal bracing in treating progressive scoliosis deformity utilizing EOS (bi-planer) imaging and SterEOS reconstruction software. Methods. EOS images of scoliosis patients being treated with bracing were obtained both in and out of their brace. These images were processed using SterEOS software to allow 3D representation, which was then compared to traditional coronal 2D parameters. Between January 2019 and January 2020, 29 patients were recruited for participation. Of these participants, 25 had a single episode of EOS imaging out of and in their brace. Additionally, 19 of the 25 participants had further episodes of EOS imaging within the study period, separated by mean 144+/-44 days. This allowed a total of 44 EOS single scan episodes for parameter analysis out of, and in the brace. Longitudinal analysis was also performed on the 19 patients who had sequential scans. Results. Participants were mean 13.8±1.1 years old at the first scan. Coronal 2D parameters, specifically Cobb Angle measurement, were accurately reproducible with SterEOS 3D measurements. Across all EOS scans (n=44) the mean major coronal curve measurement was 42.3±13.3° out of brace and 37.2±13.8° in the brace. This produced a mean correction of 4.6±4.4° (p<0.05). The correction achieved in this cohort with bracing appeared more modest than those reported in previous studies using traditional 2D coronal curve measurements1–3. The mean axial vertebral rotation (AVR) was 10.6±7.1° out of the brace and 9.6±6.8° in the brace, with a mean correction of 1.4±5.3°(p=0.14). The current study results suggested no significant change in axial vertebral rotation with brace treatment. Notably, in 17 of the 44 AVR measured, the differences were negative. That is, the AVR worsened in the brace. There was a significant moderate correlation between 3D coronal Cobb angle measured and AVR measured out of the brace for all curves. However, the change in Cobb and change in AVR with bracing did not correlate. Over sequential EOS episodes (n=19), there appeared no significant progression of 3D parameters, interpreted as the brace preventing curve progression. Conclusions. There appeared to be a consistent reduction in the scoliosis Cobb angle of the major curve with brace treatment. AVR demonstrated no significant change with bracing, with instances of worsening of AVR in the brace, which was not reflected by Cobb angle measurement. Despite this, bracing appears to have been effective with limited curve progression in sequential scans, though not in the anticipated manner of immediate in-brace curve correction.