Purpose. This study aims to identify factors that influence the Cobb angle at presentation to a tertiary referral scoliosis centre, and the outcome of the referrals. Methods. 81 consecutive patients referred were reviewed retrospectively. Hospital database, clinic letters and radiographs were examined. Patient demographics, mode of referral (GP vs. tertiary), severity and type of scoliosis were recorded. The season of referral was defined as ‘warm’ between months of June and September, and ‘cold’ between November and March. Cobb angle measurements were made independently on digital radiographs by 2 Orthopaedic trainees. Results. There were 60 females and 21 males referred. Of these patients, 31 (38%) were offered surgery. The overall mean Cobb angle was 43° (SD 22.5°), where the surgical group was 58° (SD 20°) and the non-surgical group was 33° (SD 18°), p < 0.05. The mean age of the patients for surgery was 22, compared to 19 in the non-operative group (p < 0.05). There was no significant influence of sex, season of referral, and mode of referral on operations offered. Males had a higher mean Cobb angle (52°) than female (39°) with marginal significance (p = 0.09). Advancing age correlated with increasing Cobb angle (r = 0.2, p = 0.09) with marginal significance. No other factors influenced the presenting Cobb angle. There was excellent inter-observer agreement in the Cobb angle measurements (α = 0.99). Conclusion. High Cobb angle and age were the only significant predictors for requirement of surgery in a tertiary referral scoliosis centre. Secondary or tertiary referral did not influence the severity or the outcome of patients with scoliosis. This may imply that GP direct referrals to scoliosis centres are sufficient, especially if Cobb angle measurements and age are included in the criteria. Seasonal differences in scoliosis presentation were not found, however further comparison can be made with countries with warmer climate to demonstrate the cosmetic influence. Ethics Approval: none. Interest Statement: none

Introduction: Accurate and quantitative measurements of the spine are essential for deformity diagnosis and assessment of curve progression. There is much concern related to the multiple exposures to ionizing radiation associated with the Cobb method of radiographic measurement, currently the standard procedure for diagnosis and follow-up of the progression of scoliosis. In addition, the Cobb method relies on two-dimensional analysis of a three-dimensional deformity. The Ortelius800TM aims to provide a radiation-free method for scoliosis assessment in three planes (coronal, sagittal, apical) with simultaneous automatic calculation of the Cobb angle in both coronal and sagittal views. This new device is based on direct measurement of the position of the tips of the spinous processes in space. A low intensity electromagnetic field records the spatial position of a sensor attached to the examiner’s finger while palpating the patient’s spinous processes. This study investigates the correlation of spinal deformity measurements with Ortelius800TM radiation-free system as compared to standard radiographic measured Cobb angles in order to assess Ortelius800TM clinical value while enabling a significant reduction of x-ray exposure. Methods: 124 patients diagnosed with Adolescent Idiopathic Scoliosis (AIS) from four different medical centers were measured with the Ortelius800TM system using the same standard protocol. The entire process required an average of 2 minutes. The Ortelius800TM measurements were correlated with the standard Cobb angle as measured on routine standing coronal and sagittal radiographs. The Pearson correlation coefficient was calculated for matched pair measurements. The mean difference and the absolute mean difference between measurements with the two methods was estimated. Results: Standing full-spine coronal radiographs were obtained for each patient. Radiograph analysis for these 124 patients revealed 249 deformity measurements. The deformity measurements were comprised of 142 thoracic curves with a mean of 18.3° and 107 lumbar curves with a mean of 17.4°. Lateral radiographs were obtained from 38 patients with a mean of 36.1°. Correlation between Cobb angles measured manually on standard erect posteroanterior radiographs and those calculated by this new technique showed an absolute difference between the measurements to be significantly less than +\−5° for coronal measurements and significantly less than +\−6° for sagittal measurements indicating good correlation between the two methods. Pearson’s correlation coefficient between deformity angles obtained by the two methods was highly significant (0.86) with a P value < 0.0001. The measurements from four independent sites were not significantly different. Discussion: The results reveal good correlation between the two measuring methods in both coronal and sagittal views. We propose the Ortelius800TM as a clinical tool for the routine follow-up measurements of AIS patients, thus enabling a significant reduction of radiation exposure

Purpose of the study. To establish the relation between the magnitude of the deformity in scoliosis, measured by cobb angle on radiograph & Volumetric asymmetry with the ISIS2 surface topography, and the patient perception of self image and mental health, measured with SRS-22 scores. Methodology. A total of 89 untreated patients with scoliosis were included in the study. They had clinical assessment, cobb angle measurement of radiograph and surface topography performed on the same day along with SRS-22 questionnaires. The cobb angle was measured by single surgeon using a digital PACS system, who was unaware of the volumetric asymmetry score. Volumetric asymmetry was measured by ISIS2 surface topography performed by a research nurse who was unaware of the cobb angle. Volumetric asymmetry was calculated using standard ISIS2 software. A comparison correlation of SRS scores for function, pain, self image and mental health against cobb angle and volumetric asymmetry was undertaken by clinical scientist. Scores for patient satisfaction to treatment was excluded as these were untreated patients. Statistical analysis was performed using cor. test on software R. Results. Correlation of both cobb angle and volumetric asymmetry for function and pain were statistically not significant (p value > 0.05). However for self image, correlation was statistically significant with cobb angle (p value-0.0033) and volumetric asymmetry (p value-0.00031), but the correlation was not high. Cobb angle contributed only around 10% to self image, whilst volumetric asymmetry contributed only 14%. Similarly for mental health, correlation was statistically significant with cobb angle (p value-0.0194) and volumetric asymmetry (p value-0.00559), but the correlation was not high. Cobb angle contributed only around 6.2% to mental health, whilst volumetric asymmetry contributed only 8.6%. Conclusion. Volumetric asymmetry correlates better to both mental health and self image as compared to cobb angle, but the correlation is still poor. Neither cobb angle or volumetric asymmetry can be used to predict patients self image or mental health. We are pursuing this study further to look at other parameters which may affect SRS-22 such as gender, age, type of deformity, waist asymmetry and shoulder asymmetry. Ethics approval: None. Interest Statement: None

Objective: Axially loaded MRI simulates imaging of the lumbar spine in the standing position and is useful in the assessment of spinal stenosis[. 1. ]. This study determines the ability of axially loaded spinal MRI to assess Cobb angle in patients with idiopathic scoliosis. Design: Prospective study. Newly diagnosed patients with idiopathic scoliosis were referred for MRI of the whole spine. Cobb angle measurements were made from erect AP spinal radiographs prior to MRI. Coronal MR images of the thoracic and/or lumbar spine were obtained prior to and following loading of the spine in an MR compatible compression device (Dynawell). Cobb angle measurements were made on unloaded and loaded MRI studies using the same reference points as on radiographs. Radiographic and MRI Cobb angle measurements were compared. Informed consent was obtained from all patients and the study was approved by the local Ethics Committee. Subjects: Five patients, all females with mean age 14 years (range 12–16 years) were included in the study. Outcome Measures: Six curves were compared on pre-referral erect radiographs, unloaded and loaded MRI studies, 2 in the thoracic region and 4 in the thoracolumbar region. Results: Curve characteristics and Cobb angle measurement on radiographs vs. axial unloaded and loaded MRI were as follows: Curve 1; T4-T12, 45°, 36° and 41°. Curve 2; T10-L4, 52°, 22° and 30°. Curve 3; T10-L4, 45°, 36° and 38°. Curve 4; T6-T10, 42°, 22° and 22°. Curve 5; T11-L3, 43°, 32° and 43°. Curve 6; T11-L3, 34°, 11° and 31°. Conclusions: Axial loading increases MRI Cobb angle measurements compared to unloaded studies. Initial results suggest that axial loaded MRI using the Dynawell Compression device may allow comparative measurement of Cobb angle to erect radiographs in the thoracolumbar region, but not in the thoracic region. This is likely related to the loading characteristics of the compression device, which is designed to concentrate loading in the lumbar region. Modification to include loading of the thoracic spine may improve results. The technique has the potential to replace radiography and thus reduce radiation burden to young adolescents with some types of idiopathic scoliosis

Introduction: Ronald McRae’s textbook clinical orthopaedic examination mentions “Capasso’s method. 1. of evaluation of coronal plane deformity to be the most sensitive tool of measuring cobb angle. However there is no study to date evaluating/comparing this method against popular & widely used tools viz. cobbometer and traditional protractor. Objectives: To evaluate Capasso’s method against commonly used measurement aids w.r.t measurement of cobb angle in scoliosis. Summary of background data: Studies of Cobb method of measurement have multiple sources of error and intra & inter-observer variability. The Capasso’s method which is based on “bi-uni-vocal principle” views the scoliosis curve to be an arc of circumference and to be a true reflection of angular values and hence geometrically more valid. Methods: 24 scoliosis curves were measured by three different examiners on three separate occasions one week apart by 1) Capasso’s method 2) Cobbometer and 3) Traditional protractor on same set of hard copies of digital x-rays. The three set of Cobb angle readings obtained were statistically analysed for intra & inter-observer reliability and assessed for agreement between the three methods of clinical measurement. Results: The mean intra observer variability for protractor, cobbometer & Capasso’s methods were 8.50, 5.50 10.00 respectively. The cobb angle readings obtained by Capas-so’s method was higher than the other two methods for all magnitudes of the curves (< 300, 300–600 & > 600) and was more than two times the conventional readings for curves < 300. The disagreement between Capasso’s method with either of the other two methods (cobbometer & protractor) was statistically significant (p< 0.01). Discussion: This study demonstrates that Capasso’s method significantly overestimates the magnitude of scoliotic deformity esp. for curves < 300 as compared to other existing popular measurement tools. Surgical decision making if were to be based on it would invite criticism and wrath. The present existing methods have their own limitations and the need of the day is a simple three dimensional measuring system to accurately define the magnitude of the deformity

Our aim in this prospective radiological study was to determine whether the flexibility rate calculated from radiographs obtained during forced traction under general anaesthesia, was better than that of fulcrum-bending radiographs before corrective surgery in predicting the extent of the available correction in patients with idiopathic scoliosis. We evaluated 33 patients with a Cobb angle > 60° on a standing posteroanterior radiograph, who had been treated by posterior correction. Pre-operative standing fulcrum-bending radiographs and those with forced-traction under general anaesthesia were obtained. Post-operative standing radiographs were taken after surgical correction. The mean forced-traction flexibility rate was 55% (. sd. 11.3) which was significantly higher than the mean fulcrum-bending flexibility rate of 32% (. sd. 16.1) (p < 0.001). We found no correlation between either the forced-traction or fulcrum-bending flexibility rates and the correction rate post-operatively (p = 0.24 and p = 0.44, respectively). Radiographs obtained during forced traction under general anaesthesia were better at predicting the flexibility of the curve than fulcrum-bending radiographs in curves with a Cobb angle > 60° in the standing position and may identify those patients for whom supplementary anterior surgery can be avoided

Introduction: Capasso’s method(CM) has been described in orthopaedic textbooks to be the most sensitive tool for measuring Cobb angle in scoliosis. This method based on “bi-univocal principle” views the scoliosis curve to be an arc of circumference, to be a true reflection of angular values and hence geometrically more valid. However there is no comparative study between the established measurement tools i.e. Oxford cobbometer(OC) & Traditional protractor(TP) vs. CM. Our objectives were to to evaluate the sensitivity of CM against OC & TP in scoliosis and to determine intra & inter-observer reliability of the three methods. Methods: Three independent blinded observers measured 24 digital AP radiographs of scoliosis on three separate occasions one week apart by CM, OC & TP. The three sets of readings obtained were statistically analysed for intra-observer (Cronbach’s alpha) & inter-observer [Inter-class correlation coefficient(ICC)] reliability. Results: The mean Cobb angle measured by OC was 42.4(r13-91), by TP was 45.1(r16-89) and by CM was 70.4(r 20-148). The cronbach’s was 0.94 for OC, 0.91 for TP & 0.88 for CM. The ICC was 0.96 for OC, 0.90 for TP & 0.71 for CM. The measurements obtained by CM were higher than the other two methods for all magnitudes of the curves. Conclusion: CM based on sound geometric principles is perceived to be superior to Cobb angle and has reasonable correlation(Pearson’s®=0.74) with it. However CM overestimates the magnitude of scoliosis as compared to other standard measurement tools. Management decisions based on CM would be inappropriate by current guidelines. Ethics approval: Not applicable Interest Statement: None

The purpose of this study was to establish the a)feasibility, b) reproducibility of spinal Quantec scans (a non-intrusive surface topography system) and c) the validity of the Quantec Q-angle against Cobb angles from spinal radiographs, in non-ambulant children with cerebral palsy (CP). Eighteen non-ambulant children (aged 5–11 years) with CP had successful clinical, radiological and Quantec assessment of their spine while seated in a supportive seating system. Scoliosis incidence was 72%, Cobb angles ranged from 1–73° (mean 18.2°). Quantec scanning was feasible with appropriate postural support. Mean interobserver differences were 0.5 ± 5.8° (median 1.3°, 5 / 95th percentiles lying at −7.3 / 8.5° respectively). Mean differences between Cobb and Q-angle were 0.02 ± 6.2° (median 1.0°, with 5 / 95th percentiles lying at −8.2 / 7.7° respectively). Surface topography may be used to safely monitor the spine for non-ambulant CP children. Results show similar or improved trends to previous comparisons with idiopathic scoliosis. Ovadia (2007) showed an interobserver mean difference of 6.3 ± 4.9° using an Ortelius800TM system. Thometz (2000) showed mean differences between Cobb and Q-angle ranging from 1.1–12.6 ± 4.9–10.2°. Further research is needed for the user group described in this study with larger spinal curves. Ethics approval: Ethics approval granted by Leeds (West) Research Ethics Committee. COREC number: 08/H1307/22. Interest Statement: None

The variability in measurement of angles in congenital scoliosis is not known, but it is postulated that it is larger than that in adolescent idiopathic scoliosis due to skeletal immaturity, incomplete ossification, and anomalous development of the end-vertebrae. To determine this variability, we selected 54 radiographs of adequate quality showing 67 scoliotic curves from children with congenital scoliosis. The end-vertebrae were preselected. Each curve was measured by the Cobb method on two separate occasions by six different observers, using the same goniometer and marker. The intraobserver variability was +/- 9.6 degrees and the interobserver variability +/- 11.8 degrees. If 'significant progression' is to be used as a criterion for surgical fusion in congenital scoliosis, there should be at least a 23 degrees increase, the entire range of the interobserver variability, in the curvature to ensure that the perceived increase is not due to variability in measurement.

Aims. This systematic review aims to identify 3D predictors derived from biplanar reconstruction, and to describe current methods for improving curve prediction in patients with mild adolescent idiopathic scoliosis. Methods. A comprehensive search was conducted by three independent investigators on MEDLINE, PubMed, Web of Science, and Cochrane Library. Search terms included “adolescent idiopathic scoliosis”,“3D”, and “progression”. The inclusion and exclusion criteria were carefully defined to include clinical studies. Risk of bias was assessed with the Quality in Prognostic Studies tool (QUIPS) and Appraisal tool for Cross-Sectional Studies (AXIS), and level of evidence for each predictor was rated with the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach. In all, 915 publications were identified, with 377 articles subjected to full-text screening; overall, 31 articles were included. Results. Torsion index (TI) and apical vertebral rotation (AVR) were identified as accurate predictors of curve progression in early visits. Initial TI > 3.7° and AVR > 5.8° were predictive of curve progression. Thoracic hypokyphosis was inconsistently observed in progressive curves with weak evidence. While sagittal wedging was observed in mild curves, there is insufficient evidence for its correlation with curve progression. In curves with initial Cobb angle < 25°, Cobb angle was a poor predictor for future curve progression. Prediction accuracy was improved by incorporating serial reconstructions in stepwise layers. However, a lack of post-hoc analysis was identified in studies involving geometrical models. Conclusion. For patients with mild curves, TI and AVR were identified as predictors of curve progression, with TI > 3.7° and AVR > 5.8° found to be important thresholds. Cobb angle acts as a poor predictor in mild curves, and more investigations are required to assess thoracic kyphosis and wedging as predictors. Cumulative reconstruction of radiographs improves prediction accuracy. Comprehensive analysis between progressive and non-progressive curves is recommended to extract meaningful thresholds for clinical prognostication. Cite this article: Bone Jt Open 2024;5(3):243–251

Aims. The aim of this study was to assess the ability of morphological spinal parameters to predict the outcome of bracing in patients with adolescent idiopathic scoliosis (AIS) and to establish a novel supine correction index (SCI) for guiding bracing treatment. Methods. Patients with AIS to be treated by bracing were prospectively recruited between December 2016 and 2018, and were followed until brace removal. In all, 207 patients with a mean age at recruitment of 12.8 years (SD 1.2) were enrolled. Cobb angles, supine flexibility, and the rate of in-brace correction were measured and used to predict curve progression at the end of follow-up. The SCI was defined as the ratio between correction rate and flexibility. Receiver operating characteristic (ROC) curve analysis was carried out to assess the optimal thresholds for flexibility, correction rate, and SCI in predicting a higher risk of progression, defined by a change in Cobb angle of ≥ 5° or the need for surgery. Results. The baseline Cobb angles were similar (p = 0.374) in patients whose curves progressed (32.7° (SD 10.7)) and in those whose curves remained stable (31.4° (SD 6.1)). High supine flexibility (odds ratio (OR) 0.947 (95% CI 0.910 to 0.984); p = 0.006) and correction rate (OR 0.926 (95% CI 0.890 to 0.964); p < 0.001) predicted a lower incidence of progression after adjusting for Cobb angle, Risser sign, curve type, menarche status, distal radius and ulna grading, and brace compliance. ROC curve analysis identified a cut-off of 18.1% for flexibility (sensitivity 0.682, specificity 0.704) and a cut-off of 28.8% for correction rate (sensitivity 0.773, specificity 0.691) in predicting a lower risk of curve progression. A SCI of greater than 1.21 predicted a lower risk of progression (OR 0.4 (95% CI 0.251 to 0.955); sensitivity 0.583, specificity 0.591; p = 0.036). Conclusion. A higher supine flexibility (18.1%) and correction rate (28.8%), and a SCI of greater than 1.21 predicted a lower risk of progression. These novel parameters can be used as a guide to optimize the outcome of bracing. Cite this article: Bone Joint J 2022;104-B(4):495–503

Aims. To systematically evaluate whether bracing can effectively achieve curve regression in patients with adolescent idiopathic scoliosis (AIS), and to identify any predictors of curve regression after bracing. Methods. Two independent reviewers performed a comprehensive literature search in PubMed, Ovid, Web of Science, Scopus, and Cochrane Library to obtain all published information about the effectiveness of bracing in achieving curve regression in AIS patients. Search terms included “brace treatment” or “bracing,” “idiopathic scoliosis,” and “curve regression” or “curve reduction.” Inclusion criteria were studies recruiting patients with AIS undergoing brace treatment and one of the study outcomes must be curve regression or reduction, defined as > 5° reduction in coronal Cobb angle of a major curve upon bracing completion. Exclusion criteria were studies including non-AIS patients, studies not reporting p-value or confidence interval, animal studies, case reports, case series, and systematic reviews. The GRADE approach to assessing quality of evidence was used to evaluate each publication. Results. After abstract and full-text screening, 205 out of 216 articles were excluded. The 11 included studies all reported occurrence of curve regression among AIS patients who were braced. Regression rate ranged from 16.7% to 100%. We found evidence that bracing is effective in achieving curve regression among compliant AIS patients eligible for bracing, i.e. curves of 25° to 40°. A similar effect was also found in patients with major curve sizes ranging from 40° to 60° when combined with scoliosis-specific exercises. There was also evidence showing that a low apical vertebral body height ratio, in-brace correction, smaller pre-brace Cobb angle, and daily pattern of brace-wear compliance predict curve regression after bracing. Conclusion. Bracing provides a corrective effect on scoliotic curves of AIS patients to achieve curve regression, given there is high compliance rate and the incorporation of exercises. Cite this article: Bone Joint J 2024;106-B(3):286–292

Aims. Vertebral body tethering (VBT) is a non-fusion technique to correct scoliosis. It allows correction of scoliosis through growth modulation (GM) by tethering the convex side to allow concave unrestricted growth similar to the hemiepiphysiodesis concept. The other modality is anterior scoliosis correction (ASC) where the tether is able to perform most of the correction immediately where limited growth is expected. Methods. We conducted a retrospective analysis of clinical and radiological data of 20 patients aged between 9 and 17 years old, (with a 19 female: 1 male ratio) between January 2014 to December 2016 with a mean five-year follow-up (4 to 7). Results. There were ten patients in each group with a total of 23 curves operated on. VBT-GM mean age was 12.5 years (9 to 14) with a mean Risser classification of 0.63 (0 to 2) and VBT-ASC was 14.9 years (13 to 17) with a mean Risser classification of 3.66 (3 to 5). Mean preoperative VBT-GM Cobb was 47.4° (40° to 58°) with a Fulcrum unbend of 17.4 (1° to 41°), compared to VBT-ASC 56.5° (40° to 79°) with 30.6 (2° to 69°)unbend. Postoperative VBT-GM was 20.3° and VBT-ASC Cobb angle was 11.2°. The early postoperative correction rate was 54.3% versus 81% whereas Fulcrum Bending Correction Index (FBCI) was 93.1% vs 146.6%. The last Cobb angle on radiograph at mean five years’ follow-up was 19.4° (VBT-GM) and 16.5° (VBT-ASC). Patients with open triradiate cartilage (TRC) had three over-corrections. Overall, 5% of patients required fusion. This one patient alone had a over-correction, a second-stage tether release, and final conversion to fusion. Conclusion. We show a high success rate (95%) in helping children avoid fusion at five years post-surgery. VBT is a safe technique for correction of scoliosis in the skeletally immature patient. This is the first report at five years that shows two methods of VBT can be employed depending on the skeletal maturity of the patient: GM and ASC. Cite this article: Bone Jt Open 2022;3(2):123–129

Introduction. There is no consensus among scoliosis surgeons on which surface topography method and parameters may be used as an alternative to serial radiography to monitor scoliosis progression. The aim of this study was to evaluate the inter-correlation among surface rotation (4-D formetric II) with 3-D Quantec scan and 2-D cobb's angle measurements for assessing torso asymmetry in adolescent idiopathic scoliosis (AIS). Materials & Methods. A prospective cohort of consecutive 24 patients with adolescent idiopathic scoliosis was accrued from the departmental scoliosis surface topography database. This group comprised of conservatively treated, Spinecor brace treated and postoperative patients in order to assess the wider utility and validity of 2 different surface topography methods (Formetric II & Quantec Spinal Imaging System). Parameters assessed were Q-angle, Suzuki hump sum, Posterior Trunk Symmetry Index (POTSI), surface rotation (rms), surface rotation (max) and maximum Cobb's angle on concurrently done scoliograms. Results. There were 3 male and 21 female patients (87.5%) at a mean age of 14.1 years (range, 10-20 years). Maximum Cobb's angle ranged from 9 degrees to 80 degrees. There was a significant correlation between Cobb angle (mean-35.1°) and Q-angle (mean-21.8°). Scatter plot and regression analysis showed a linear relationship between surface rotation (mean-9.9 root mean square) and POTSI (mean-42.5) as well as Q-angle. Suzuki hump sum was a less reliable parameter. Conclusions. Formimetric scans showed a linear correlation and reproducibility in patients with AIS receiving conservative treatment for smaller magnitude curves, when compared to Quantec scan. Due to ease of use, colourful and multi-mode representation of spinal deformity, Formetric may have an edge of preference for better clinic consultation to patient/parental appreciation of cosmetic issues and gain following treatment

Aims. Historically, patients undergoing surgery for adolescent idiopathic scoliosis (AIS) have been nursed postoperatively in a critical care (CC) setting because of the challenges posed by prone positioning, extensive exposures, prolonged operating times, significant blood loss, major intraoperative fluid shifts, cardiopulmonary complications, and difficulty in postoperative pain management. The primary aim of this paper was to determine whether a scoring system, which uses Cobb angle, forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and number of levels to be fused, is a valid method of predicting the need for postoperative critical care in AIS patients who are to undergo scoliosis correction with posterior spinal fusion (PSF). Methods. We retrospectively reviewed all AIS patients who had undergone PSF between January 2018 and January 2020 in a specialist tertiary spinal referral centre. All patients were assessed preoperatively in an anaesthetic clinic. Postoperative care was defined as ward-based (WB) or critical care (CC), based on the preoperative FEV1, FVC, major curve Cobb angle, and the planned number of instrumented levels. Results. Overall, 105 patients were enrolled. Their mean age was 15.5 years (11 to 25) with a mean weight of 55 kg (35 to 103). The mean Cobb angle was 68° (38° to 122°). Of these, 38 patients were preoperatively scored to receive postoperative CC. However, only 19% of the cohort (20/105) actually needed CC-level support. Based on these figures, and an average paediatric intensive care unit stay of one day before stepdown to ward-based care, the potential cost-saving on the first postoperative night for this cohort was over £20,000. There was no statistically significant difference between the Total Pathway Score (TPS), the numerical representation of the four factors being assessed, and the actual level of care received (p = 0.052) or the American Society of Anesthesiologists grade (p = 0.187). Binary logistic regression analysis of the TPS variables showed that the preoperative Cobb angle was the only variable which significantly predicted the need for critical care. Conclusion. Most patients undergoing posterior fusion surgery for AIS do not need critical care. Of the readily available preoperative measures, the Cobb angle is the only predictor of the need for higher levels of care, and has a threshold value of 74.5°. Cite this article: Bone Joint J 2024;106-B(7):713–719

Aims. The aim of this study was to review the current evidence surrounding curve type and morphology on curve progression risk in adolescent idiopathic scoliosis (AIS). Methods. A comprehensive search was conducted by two independent reviewers on PubMed, Embase, Medline, and Web of Science to obtain all published information on morphological predictors of AIS progression. Search items included ‘adolescent idiopathic scoliosis’, ‘progression’, and ‘imaging’. The inclusion and exclusion criteria were carefully defined. Risk of bias of studies was assessed with the Quality in Prognostic Studies tool, and level of evidence for each predictor was rated with the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. In all, 6,286 publications were identified with 3,598 being subjected to secondary scrutiny. Ultimately, 26 publications (25 datasets) were included in this review. Results. For unbraced patients, high and moderate evidence was found for Cobb angle and curve type as predictors, respectively. Initial Cobb angle > 25° and thoracic curves were predictive of curve progression. For braced patients, flexibility < 28% and limited in-brace correction were factors predictive of progression with high and moderate evidence, respectively. Thoracic curves, high apical vertebral rotation, large rib vertebra angle difference, small rib vertebra angle on the convex side, and low pelvic tilt had weak evidence as predictors of curve progression. Conclusion. For curve progression, strong and consistent evidence is found for Cobb angle, curve type, flexibility, and correction rate. Cobb angle > 25° and flexibility < 28% are found to be important thresholds to guide clinical prognostication. Despite the low evidence, apical vertebral rotation, rib morphology, and pelvic tilt may be promising factors. Cite this article: Bone Joint J 2022;104-B(4):424–432

Aims. The aim of this study was to assess whether supine flexibility predicts the likelihood of curve progression in patients with adolescent idiopathic scoliosis (AIS) undergoing brace treatment. Methods. This was a retrospective analysis of patients with AIS prescribed with an underarm brace between September 2008 to April 2013 and followed up until 18 years of age or required surgery. Patients with structural proximal curves that preclude underarm bracing, those who were lost to follow-up, and those who had poor compliance to bracing (<16 hours a day) were excluded. The major curve Cobb angle, curve type, and location were measured on the pre-brace standing posteroanterior (PA) radiograph, supine whole spine radiograph, initial in-brace standing PA radiograph, and the post-brace weaning standing PA radiograph. Validation of the previous in-brace Cobb angle regression model was performed. The outcome of curve progression post-bracing was tested using a logistic regression model. The supine flexibility cut-off for curve progression was analyzed with receiver operating characteristic curve. Results. A total of 586 patients with mean age of 12.6 years (SD 1.2) remained for analysis after exclusion. The baseline Cobb angle was similar for thoracic major curves (31.6° (SD 3.8°)) and lumbar major curves (30.3° (SD 3.7°)). Curve progression was more common in the thoracic curves than lumbar curves with mean final Cobb angles of 40.5° (SD 12.5°) and 31.8° (SD 9.8°) respectively. This dataset matched the prediction model for in-brace Cobb angle with less mean absolute error in thoracic curves (0.61) as compared to lumbar curves (1.04). Reduced age and Risser stage, thoracic curves, increased pre-brace Cobb angle, and reduced correction and flexibility rates predicted increased likelihood of curve progression. Flexibility rate of more than 28% has likelihood of preventing curve progression with bracing. Conclusion. Supine radiographs provide satisfactory prediction for in-brace correction and post-bracing curve magnitude. The flexibility of the curve is a guide to determine the likelihood for brace success. Cite this article: Bone Joint J 2020;102-B(2):254–260