Three-dimensional spine parameters can differentiate between progressive and nonprogressive patients with AIS at the initial visit: a retrospective analysis

Identifying and validating prognostic parameters to predict curve progression in adolescents with idiopathic scoliosis

PURPOSE

This study aimed to identify and validate prognostic factors to predict scoliosis progression.

METHODS

One hundred sixty-two girls, aged 13.5 ± 1.7 years old, diagnosed with idiopathic scoliosis were recruited. One hundred were used for model development, and 62 for testing, in which the number of progression cases was 25 and 11, respectively. All participants were scanned by an ultrasound (US) system for two consecutive visits (baseline and follow-up). The baseline parameters included (a) demographic: age, body mass index (BMI), and menarche status; (b) radiographic: X-ray Cobb angle, number-of-curve (NOC), and Risser sign; (c) ultrasonic: US Cobb, maximum axial vertebral rotation (AVR), Cobb angle at the plane of maximum curvature (PMC), kyphotic angle (KA) and reflection coefficient (RC) index. For the follow-up visit, only the US Cobb was recorded. The demographic and X-ray parameters were extracted from the scoliosis clinical records. The US parameters were measured by trained raters with good measurement reliability. The prediction model was developed using logistic regression analysis.

RESULTS

The final predictors were US Cobb change, RC index, and NOC, and the probability of curve progression risk was Log (p/1-p) = -1.40 + 0.28(US Cobb change)-39.45(RC) + 1.36 (NOC). The model achieved sensitivity, specificity, and accuracy of 90% on the 62 test dataset, which was much better than using US Cobb change only.

CONCLUSIONS

The results indicated that participants with lower RC (weaker bone, RC ≤ 0.06), larger US Cobb change (≥ 5°), and multiple curvatures (NOC > 1) were at a higher risk of curve progression. A large study including more progression cases is needed for further validation.

Using ultrasound reflection coefficient index and other clinical parameters to predict the risk of progression in adolescents with idiopathic scoliosis (AIS)- a pilot study

PURPOSE

To determine the association of the ultrasound reflection coefficient index and other clinical parameters to predict curve progression in children with AIS.

METHODS

Sixty-six females (13.9 ± 1.5 years old) under observation with baseline Cobb angle (24.4 ± 10.4°) consented and participated. Besides the standard clinical procedures, all participants were scanned by an ultrasound (US) imager in a standing position. All participants had been followed, and the average follow-up visit was 7.5 ± 3.1 months. Five parameters were investigated, including the Cobb angle and the Risser sign measured from the radiographs, and the kyphotic angle (KA), the axial vertebral rotation (AVR), and the reflection coefficient (RC) index measured from the ultrasonographs. The curve was considered progressed when the Cobb angle measured on two consecutive radiographs was increased by more than 5°.

RESULTS

Among the 5 parameters, the KA, RC index, and Risser sign were found to be significantly associated with progression (p < 0.05). Children who had KA ≤ 38° and RC ≤ 0.06 showed higher chances of progression (62%) versus children with KA > 38° and RC > 0.06.

CONCLUSION

This pilot study showed that curve progression is associated with the Risser sign, KA, and RC index. Other parameters and a more extensive clinical study should be combined to develop a higher-accuracy prediction model.

Prediction of the upright articulated spine shape in the operating room using conditioned neural kernel fields

Anterior vertebral tethering (AVT) is a non-invasive spine surgery technique, treating severe spine deformations and preserving lower back mobility. However, patient positioning and surgical strategies greatly influences postoperative results. Predicting the upright geometry from pediatric spines is needed to optimize patient positioning in the operating room (OR) and improve surgical outcomes, but remains a complex task due to immature bone properties. We propose a framework used in the OR predicting the upright spine geometry at the first visit following surgery in idiopathic scoliosis patients. The approach first creates a 3D model of the spine while the patient is on the operating table. For this, multiview Transformers that combine images from different viewpoints are used to generate the intraoperative pose. The postoperative upright shape is then predicted on-the-fly using implicit neural fields, which are trained from geometries at different time points and conditioned with surgical parameters. A Signed Distance Function for shape constellations is used to handle the variability in spine appearance, capturing a disentangled latent domain of the articulation vectors, with separate encoding vectors representing both articulation and shape parameters. A regularization criterion based on a pre-trained group-wise trajectory of spine transformations generates complete spine models. A training set of 652 patients with 3D models was used to train the model, tested on a distinct cohort of 83 surgical patients. The framework based on neural kernels predicted upright 3D geometries with a mean 3D error of 1.3±0.5mm in landmarks points, and IoU of 95.9% in vertebral shapes when compared to actual postop models, falling within the acceptable margins of error below 2 mm.

Pre-operative parameters influencing vertebral body tethering outcomes: patient's characteristics play an important role in determining the outcomes at a minimum of 2 years post-op

PURPOSE

The aim of this study is to determine preoperative predictors of good radiographic outcomes in VBT patients at a minimum 2-year follow-up.

METHODS

From a single-center dataset, we reviewed patients who underwent VBT from January 2014 to November 2018. Data analysis included age, gender, Risser grade and biometric data. Radiographically, maximum Cobb angle, C-DAR and apical vertebral and disc wedging were measured preop and at a minimum 2-year follow-up. Patients were divided into two cohorts following two different outcome measures: (1) vertebral growth modulation, those patients that growth modulated or corrected ≥ 5° and those who did not; and (2) Maximum Cobb angle at 2 years, < and ≥ 40°. Student T and Chi2 tests were used for comparison and a multiple linear correlation test was implemented between statistically significant variables.

RESULTS

79 patients were recruited. 26 patients (33%) did growth modulate their spine at 2-year follow-up. These patients were significantly younger, and more skeletally immature with less height (147 cm vs 155 cm; p < 0.0001), weight (38 kg vs. 45 kg; p = 0.0009) and BMI (17 vs 18.8; p = 0.0229) as those who did not. Multiple linear regression model with these variables resulted in a moderate correlation (r2 = 0.234). 67 patients (85%) finished at a 2-year follow-up with a maximum Cobb angle < 40°. These patients were also younger and skeletally immature. We found significant differences in outcome 2 regarding the average preoperative maximum Cobb angle (48.5° ± 9.5 vs. 59.1° ± 10), average C-DAR (7 ± 1.5 vs. 8.5 ± 2.1), average apical vertebral wedging (6.5° vs. 8.3°), average vertebral/disc wedging ratio (1.5 vs. 2.4) and the average immediate postoperative Cobb angle (25° vs. 38°). These variables predicted a 36% of the variation in final Cobb angle measurement at a 2-year follow-up (r2 = 0.362).

CONCLUSION

Curve severity determined by a preoperative C-DAR, preoperative Cobb angles and immediate postoperative Cobb angle are significantly related to curves < 40° at a minimum 2-year follow-up, while the potential to growth modulate the spine is more dependent on skeletal maturity, lower body weight and lower BMI. These patients' characteristics should be considered preoperatively.

Radiographic outcome after vertebral body tethering of the lumbar spine

INTRODUCTION

Multiple studies have analyzed the outcome after thoracic Vertebral Body Tethering (VBT). The results seem reproducible with most studies reporting coronal correction rates around 50% and a tether breakage rate near 20% at two years follow-up. There is a paucity of data on lumbar VBT, and no study has yet analyzed the radiographic outcome after lumbar VBT in a double tether technique at two years follow-up, which was the aim of this study.

METHODS

This is a retrospective, single surgeons' data analysis of all consecutive immature patients who have had VBT of the lumbar spine (to L3 or L4) between January 2019 and September 2020. Primary interest focused on coronal curve correction at two years post-operatively. Suspected tether breakages were analyzed separately and defined as an angular change of more than 5° between two adjacent screws.

RESULTS

Forty-one patients were eligible for this study and 35 (85%) had complete two-year follow-up data. Average age at surgery was 14.3 years. All patients had a Sanders stage of 7 or below. Average curve correction for thoracolumbar/lumbar curves at two years follow-up was 50%. 90% of patients had at least one level with a suspected tether breakage. No patient required a revision surgery within two years from surgery but two patients were surgically revised after two years.

CONCLUSION

VBT in the lumbar spine resulted in 50% coronal curve correction two years post-operatively despite a tether breakage in 90% of patients.

Postoperative changes in rib cage deviation in adolescent idiopathic scoliosis

BACKGROUND

Scoliosis causes changes in the thorax, but it is unclear what type of changes occur in the thoracic profile after scoliosis surgery.

OBJECTIVE

To investigate changes in rib cage deviation in the postoperative period after adolescent idiopathic scoliosis (AIS) surgery.

METHODS

Forty-four patients with AIS with a main right thoracic curvature underwent posterior surgical fusion (PSF), and radiological parameters of the spine and thorax were evaluated.

RESULTS

The correction rates of main thoracic curve (MT)-Cobb angle at immediate after surgery and postoperative follow-up (2 years) were 64% and 66%, respectively. At these two postoperative time points, the correction rates of height of thoracic vertebrae 1 to 12 (T1T12) were 10% and 12%; the correction rates of Rib-vertebra angle difference (RVAD) were 59% and 52%; the correction rates of Apical rib hump prominence (RH) were 58% and 76%; while the correction rates of Apical vertebral body-rib ratio (AVB-R) were 23% and 25%, respectively. Statistical analysis showed that all these radiological parameters at the two postoperative time points were significantly different from the preoperative values (p< 0.001). There were significant correlations between MT-Cobb angle and T1-T12 height (p< 0.001), RVAD (p< 0.001), RH (p< 0.001), and AVB-R (p< 0.001).

CONCLUSIONS

Posterior spinal fusion appears to be effective at correcting scoliosis, and the correction of rib cage deviation also plays an important role.

Scoliosis and Prognosis-a systematic review regarding patient-specific and radiological predictive factors for curve progression

INTRODUCTION

Idiopathic scoliosis, defined as a > 10° curvature of the spine in the frontal plane, is one of the most common spinal deformities. Age, initial curve magnitude and other parameters define whether a scoliotic deformity will progress or not. Still, their interactions and amounts of individual contribution are not fully elaborated and were the aim of this systematic review.

METHODS

A systematic literature search was conducted in the common databases using MESH terms, searching for predictive factors of curve progression in adolescent idiopathic scoliosis ("adolescent idiopathic scoliosis" OR "ais" OR "idiopathic scoliosis") AND ("predictive factors" OR "progression" OR "curve progression" OR "prediction" OR "prognosis"). The identified and analysed factors of each study were rated to design a top five scale of the most relevant factors.

RESULTS

Twenty-eight investigations with 8255 patients were identified by literature search. Patient-specific risk factors for curve progression from initial curve were age (at diagnosis < 13 years), family history, bone mineral status (< 110 mg/cm³ in quantitative CT) and height velocity (7-8 cm/year, peak 11.6 ± 1.4 years). Relevant radiological criteria indicating curve progression included skeletal maturity, marked by Risser stages (Risser < 1) or Sanders Maturity Scale (SMS < 5), the initial extent of the Cobb angle (> 25° progression) and curve location (thoracic single or double curve).

DISCUSSION

This systematic review summarised the current state of knowledge as the basis for creation of patient-specific algorithms regarding a risk calculation for a progressive scoliotic deformity. Curve magnitude is the most relevant predictive factor, followed by status of skeletal maturity and curve location.

Brace Effectiveness Is Related to 3-Dimensional Plane Parameters in Patients with Adolescent Idiopathic Scoliosis

BACKGROUND

Although scoliosis is a 3-dimensional (3D) deformity, little research has been performed on the use of 3D imaging in brace curve correction. The purpose of the present study was to determine the effect of axial-plane parameters on the outcomes of bracing with a thoracolumbosacral orthosis for adolescent idiopathic scoliosis.

METHODS

This prospective longitudinal cohort study included patients with adolescent idiopathic scoliosis who fulfilled the criteria for bracing according to the Scoliosis Research Society, and was conducted from the time the patient began wearing the brace through a minimum follow-up of 2 years or until a surgical procedure was performed. Radiographs made with use of an EOS Imaging System were used to reconstruct 3D images of the spine at the pre-brace, immediate in-brace, 1-year in-brace, and latest follow-up out-of-brace stages. Univariate and multiple linear regressions were performed to determine the association between axial rotation correction and curve progression at the time of the latest follow-up. Logistic regressions were performed to model the probability of risk of progression.

RESULTS

Fifty-three patients were enrolled, and 46 patients were included in the analysis. At the time of the latest follow-up, 30 patients did not experience curve progression and 16 patients had curve progression. There was no difference in baseline demographic characteristics between groups. For the transverse-plane parameters, there was a significant difference between non-progression and progression groups in pre-brace apical vertebral rotation (4.5° ± 11.2° compared with -2.4° ± 9.8°, respectively; p = 0.044) and in 1-year in-brace apical vertebral rotation correction velocity (2.0° ± 5.0°/year compared with -1.7° ± 4.4°/year, respectively; p = 0.016). Logistic regression analysis showed that pre-brace apical vertebral rotation (odds ratio, 1.063; 95% confidence interval, 1.000 to 1.131; p = 0.049) and 1-year in-brace apical vertebral rotation correction velocity (odds ratio, 1.19; 95% confidence interval, 1.021 to 1.38; p = 0.026) were associated with an increased risk of curve progression. There was no difference in Scoliosis Research Society 22-Item scores between patients who experienced curve progression and those who did not.

CONCLUSIONS

In this prospective study, we demonstrated that axial-plane parameters and the correction of these parameters during bracing are related to the successful use of the brace.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Intermediate-term annualized curve progression of adolescent idiopathic scoliosis curves measuring 40° or greater

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

The objective of this study was to examine intermediate-term progression for a large series of patients with adolescent idiopathic scoliosis (AIS) with curves 40° or greater.

BACKGROUND

Curve progression in AIS has been well documented for smaller curves in adolescence up to skeletal maturity; however, the data on curve progression past 40° or into adulthood are limited. With many surgeons recommending surgical correction when patients reach this threshold, it is important to understand the radiographic progression of curves into adulthood.

METHODS

A database of all patients seen by a single surgeon from 1984 through 2018 with AIS curves progressing to at least 40° entered prospectively was utilized for this study. This included a total of 738 patients. Curve progression was analyzed overall and stratified by length of follow-up, curve location, and Risser stage at the time of presentation among other variables. Curve magnitude and Risser stage designations in this study were validated by performing a separate inter- and intrarater agreement study using four independent reviewers reading 50 patients' Cobb angle and Risser stage blinded in triplicate to examine the reliability of the study measurements.

RESULTS

Annualized curve progression (ACP) averaged 6.3 ± 10.4°. ACP varied with length of follow-up: patients with up to 1 year of follow-up had an average ACP of 11.5 ± 17.0°, while those with 1-2 years had 8.2 ± 8.8°, and 2-5 years had 3.7 ± 4.1°, tapering off further from there. Risser stage 0 or 1 was associated with the highest ACP as compared to Risser stage 2-3 or 4-5. Intraclass correlation (ICC) values for Cobb angle measurement and Risser stage designations from four raters measuring 50 patients' measures, blinded and in triplicate, were all > 0.80, signifying a high degree of reliability within and between readers.

CONCLUSIONS

Annualized curve progression for 40° and greater curves was not linear over time; it was greatest immediately after a curve reaches 40° and tapered off over the next decade. Immature Risser stage at presentation was strongly associated with increasing ACP at all time frames.

LEVEL OF EVIDENCE

Prognostic Level I.

Association Between Vertebral Rotation Pattern and Curve Morphology in Adolescent Idiopathic Scoliosis

OBJECTIVES

Although rotation is an important aspect of pathogenesis of adolescent idiopathic scoliosis (AIS), there are no studies demonstrating rotation pattern by directly measuring rotation angle in computed tomography (CT) images. The present retrospective comparative radiographic study was conducted to evaluate the rotation pattern in AIS and its relation to curve morphology and Lenke classification.

METHODS

The study included 245 patients diagnosed with AIS and evaluated with a preoperative CT scan. Rotation angle of each vertebrae was measured using reconstructed axial CT images. Lenke classification of scoliosis curvature, Cobb angle, location of apical vertebra and end vertebra, level of most rotated vertebra (MRV), and rotational shift vertebra were recorded. Student's t-test, analysis of variance test, and correlation analysis were performed to identify the characteristics of rotation patterns in each Lenke type.

RESULTS

The rotation angle of MRV was significantly correlated with the Cobb angle. The level of MRV and rotation angle of MRV demonstrated significant correlation in both the main thoracic curve and lumbar curve, which signified that MRV located near the thoracolumbar junction is related to more severe rotational deformity. The level of MRV was also significantly correlated to the Cobb angle in both the main thoracic curve and lumbar curve. The types of structural curves proximal to major structural curves, such as type 2, 4, and 6, demonstrated more severe rotational and coronal plane deformities as compared with types 1, 3, and 5.

CONCLUSIONS

Curves with different Lenke types demonstrated different levels of MRV and severity of rotation. The results suggest that different center levels of rotation, signified by MRV, are a factor determining curve morphology. The findings would be a basis of connection between 2-dimensional classification and transverse plane deformity.

A Predictive Model of Progression for Adolescent Idiopathic Scoliosis Based on 3D Spine Parameters at First Visit

MINI: The aim of this prospective cohort study was to improve the prediction of curve progression in AIS. By adding the 3D morphology parameters at first visit, the predictive model explains 65% of the variability. It is one of the greatest advances in the understanding of scoliosis progression in the last 30 years.

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

The objective of the present study was to design a model of AIS progression to predict Cobb angle at full skeletal maturity, based on curve type, skeletal maturation, and 3D spine parameters available at first visit.

SUMMARY OF BACKGROUND DATA

Adolescent idiopathic scoliosis (AIS) is a three-dimensional (3D) spinal deformity that affects 1% of adolescents. Curve severity is assessed using the Cobb angle. Prediction of scoliosis progression remains challenging for the treating physician and is currently based on curve type, severity, and maturity. The objective of this study was to develop a predictive model of final Cobb angle, based on 3D spine parameters at first visit, to optimize treatment.

METHODS

A prospective cohort of AIS patients at first orthopedic visit was enrolled between 2006 and 2010, all with 3D reconstructions. Measurements of five types of descriptors were obtained: angle of plane of maximum curvature, Cobb angles, 3D wedging, rotation, and torsion. A general linear model analysis with backward selection was done with final Cobb angle (either just before surgery or at skeletal maturity) as outcome and 3D spine parameters and clinical parameters as predictors.

RESULTS

Of 195 participants, 172 (88%) were analyzed; average age at presentation was 12.5 ± 1.3 years and mean follow-up to outcome, 3.2 years. The final model includes significant predictors: initial skeletal maturation, curve type, frontal Cobb angle, angle of plane of maximal curvature, and 3D disk wedging (T3-T4, T8-T9) and achieved a determination coefficient (R) = 0.643. Positive and negative predictive values to identify a curve of 35 degrees are 79% and 94%.

CONCLUSION

This study developed a predictive model of spinal curve progression in scoliosis based on first-visit information. The model will help the treating physician to initiate appropriate treatment at first visit.

LEVEL OF EVIDENCE

3.

Is It Growth or Natural History? Increasing Spinal Deformity After Sanders Stage 7 in Females With AIS

BACKGROUND

Accurate prognosis and treatment decisions in adolescent idiopathic scoliosis (AIS) demand a reliable radiographic marker of growth cessation. Specifically, Sanders Stage 7 (SS7) is a useful marker of spine growth cessation in females and is proposed as a bracing endpoint. The purpose of this study was to determine the amount of curve progression noted in female individuals with AIS after achieving SS7. We hypothesize that a subset of patients continues to progress at a greater rate than the natural history at SS7.

METHODS

This retrospective review included female patients with AIS treated at a single institution from May 2008 to 2018. Patients required a hand radiograph demonstrating SS7 and concurrent spine radiograph measuring <50 degrees, plus 2-year follow-up spine radiograph. Curve types were categorized by the modified Lenke Classification. Risser grade, menarche, height, weight, and bracing data were collected. Progression was defined as an increase of the main curve ≥5 degrees. Comparison between groups was analyzed using independent t tests and χ or Fisher exact tests as appropriate. Binary logistic regressions were used to construct a model predictive of progressing beyond 50 degrees or undergoing surgery.

RESULTS

A total of 89 patients met inclusion criteria, average main curve magnitude 33 degrees (SD 9) at SS7 and 38 degrees (SD 11) at 2-year follow-up. Forty-five (51%) patients progressed ≥5 degrees and 17 (19%) progressed at least 10 degrees. Seventy patients had curves <40 degrees at SS7 and 22 (31%) progressed to >40 degrees at 2 years. Eleven (12%) patients progressed to >50 degrees or had surgery at 2-year follow-up. Receiver operating characteristic curve analysis identified a threshold of 39.5 degrees curvature at SS7 associated with progression to >50 degrees or surgery (area under the curve=0.94, P<0.001, sensitivity=100%, specificity=87%). Patients with initial curves >40 degrees did have additional height gained (2.1 cm; SD 1.5), but this was not different than those <40 degrees, P>0.05. In addition, no other variables had statistically significant association with those that progressed (P>0.05).

CONCLUSIONS

A curve >40 degrees at SS7 is at high risk for progressing to a curve measuring >50 degrees or requiring surgery. Those with curves below this threshold still have potential to make clinically significant progression after skeletal maturity. Follow-up of patients beyond SS7 is essential for curves measuring >40 degrees. Reaching SS7 with a curve <50 degrees may not be the endpoint for curve progression, even if predictive of the end of spinal growth.

LEVEL OF EVIDENCE

Level III-retrospective research study.

Differences in vertebral morphology around the apical vertebrae between neuromuscular scoliosis and idiopathic scoliosis in skeletally immature patients: a three-dimensional morphometric analysis

Background

Recent morphological analyses of vertebrae in patients with scoliosis have revealed three-dimensional (3D) deformities in the vertebral bodies. However, it remains controversial whether these deformities are secondary changes caused by asymmetrical vertebral loading or primary changes caused by aberrant asymmetrical vertebral growth. Furthermore, the difference in vertebral morphology between scoliosis with different pathogeneses remains unclear. This study was aimed to investigate the difference in the coronal asymmetry of vertebral bodies between neuromuscular scoliosis (NS) in Duchenne muscular dystrophy (DMD) and idiopathic scoliosis (IS) using in vivo 3D analysis.

Methods

Twelve male skeletally immature patients with NS in DMD and 13 female skeletally immature patients with IS who underwent corrective fusion at our institution were included retrospectively. 3D bone models of the apical and adjacent upper and lower vertebrae in the major curve in the NS patients and in the main and compensatory curves in the IS patients were constructed using an image processing workstation. The heights of the concave and convex sides of the vertebral bodies were measured at the anterior, middle, and posterior and the concave-to-convex vertebral height ratios (VHR) were calculated.

Results

The mean VHRs (anterior/middle/posterior) for the main curve for IS (0.897 ± 0.072/0.832 ± 0.086/0.883 ± 0.059) were significantly smaller than those for NS (0.970 ± 0.048/0.934 ± 0.081/0.958 ± 0.043) in all three parts (p < 0.001). Those of the compensatory curve in IS (0.968 ± 0.045/0.942 ± 0.067/0.967 ± 0.046) did not differ significantly from the NS values in any part.

Conclusions

When compared to the wedging of the vertebral bodies around apical vertebrae in the major curve in NS, which was caused by asymmetric loading, the wedge deformities in both the main and compensatory curves in IS were more severe than would be expected. Our results indicated that morphometric characteristics of vertebral bodies differed according to the pathogenesis of scoliosis and that the pathology of the wedging of vertebral bodies in IS could not be a result only of asymmetric loading to the vertebral bodies.

Early Detection of Progressive Adolescent Idiopathic Scoliosis: A Severity Index

STUDY DESIGN

Early detection of progressive adolescent idiopathic scoliosis (AIS) was assessed based on 3D quantification of the deformity.

OBJECTIVE

Based on 3D quantitative description of scoliosis curves, the aim is to assess a specific phenotype that could be an early detectable severity index for progressive AIS.

SUMMARY OF BACKGROUND DATA

Early detection of progressive scoliosis is important for adapted treatment to limit progression. However, progression risk assessment is mainly based on the follow up, waiting for signs of rapid progression that generally occur during the growth peak.

METHODS

Sixty-five mild scoliosis (16 boys, 49 girls, Cobb Angle between 10 and 20°) with a Risser between 0 and 2 were followed from their first examination until a decision was made by the clinician, either considering the spine as stable at the end of growth (26 patients) or planning to brace because of progression (39 patients). Calibrated biplanar x-rays were performed and 3D reconstructions of the spine allowed calculating six local parameters related to main curve deformity. For progressive curve 3D phenotype assessment, data were compared with those previously assessed for 30 severe scoliosis (Cobb Angle > 35°), 17 scoliosis before brace (Cobb Angle > 29°) and 53 spines of nonscoliosis subjects. A predictive discriminant analysis was performed to assess similarity of mild scoliosis curves either to those of scoliosis or nonscoliosis spines, yielding a severity index (S-index). S-index value at first examination was compared with clinical outcome.

RESULTS

At the first exam, 53 out of 65 predictions (82%) were in agreement with actual clinical outcome. Approximately, 89% of the curves that were predicted as progressive proved accurate.

CONCLUSION

Although still requiring large scale validation, results are promising for early detection of progressive curves.

LEVEL OF EVIDENCE

2.

3-D Morphology Prediction of Progressive Spinal Deformities From Probabilistic Modeling of Discriminant Manifolds

We introduce a novel approach for predicting the progression of adolescent idiopathic scoliosis from 3-D spine models reconstructed from biplanar X-ray images. Recent progress in machine learning has allowed to improve classification and prognosis rates, but lack a probabilistic framework to measure uncertainty in the data. We propose a discriminative probabilistic manifold embedding where locally linear mappings transform data points from high-dimensional space to corresponding low-dimensional coordinates. A discriminant adjacency matrix is constructed to maximize the separation between progressive (P) and nonprogressive (NP) groups of patients diagnosed with scoliosis, while minimizing the distance in latent variables belonging to the same class. To predict the evolution of deformation, a baseline reconstruction is projected onto the manifold, from which a spatiotemporal regression model is built from parallel transport curves inferred from neighboring exemplars. Rate of progression is modulated from the spine flexibility and curve magnitude of the 3-D spine deformation. The method was tested on 745 reconstructions from 133 subjects using longitudinal 3-D reconstructions of the spine, with results demonstrating the discriminatory framework can identify between P and NP of scoliotic patients with a classification rate of 81% and the prediction differences of 2.1° in main curve angulation, outperforming other manifold learning methods. Our method achieved a higher prediction accuracy and improved the modeling of spatiotemporal morphological changes in highly deformed spines compared with other learning methods.

Three-dimensional reconstruction using stereoradiography for evaluating adult spinal deformity: a reproducibility study

PURPOSE

In addition to the sagittal alignment, impact of transverse plane parameters (TPP) and rotatory subluxation on patients reported outcomes were highlighted. One of the hypotheses for genesis of degenerative scoliosis is disc degeneration with increased axial vertebral (AVR) and intervertebral rotation (AIR). Therefore, TPP analysis at early stage of the scoliosis seems of particular interest. This study aims at assessing reliability of tridimensional (3D) reconstructions of adult spinal deformity (ASD) patients.

METHODS

Thirty ASD patients underwent biplanar radiographs and were divided into two groups (Cobb angle >30° or <30°). Spinal parameters and TPP (apical AVR, AIR of upper and lower level of main curve) were measured. Four operators performed 3D reconstructions twice. Intra and inter-observer reliabilities were analyzed using ISO standard 5725-2, to quantify the global standard deviation of reproducibility (S _R).

RESULTS

Mean Cobb angle was 31°, mean age 55 years (70% of female). Mean values of apical AVR, upper and lower level AIR were, respectively, 16° ± 15°, 6° ± 6° and 5° ± 5°. Spinopelvic parameters S _R were below 4.5°. For Cobb angle <30°, S _R was 7.8°, 9.6°, 4.5° and 4.9°, respectively, for AVR apex, torsion index, upper and lower AIR. Reliability was worse in the group of patients with Cobb angle above 30°.

CONCLUSIONS

3D analysis was reliable for Cobb and sagittal parameters. 3D analysis for TPP was reproducible when Cobb is below 30°. However, uncertainty is larger for Cobb above 30°. Nevertheless, 3D reconstructions could help surgeons to anticipate onset of rotatory subluxation while assessing axial rotation evolution for small deformity and choose best delay for surgical treatment.

Predicting success or failure of brace treatment for adolescents with idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is a three-dimensional spinal deformity. Brace treatment is a common non-surgical treatment, intended to prevent progression (worsening) of the condition during adolescence. Estimating a braced patient's risk of progression is an essential part of planning treatment, so method for predicting this risk would be a useful decision support tool for practitioners. This work attempts to discover whether failure of brace treatment (progression) can be predicted at the start of treatment. Records were obtained for 62 AIS patients who had completed brace treatment. Subjects were labeled as "progressive" if their condition had progressed despite brace treatment and "non-progressive" otherwise. Wrapper-based feature selection selected two useful predictor variables from a list of 14 clinical measurements taken from the records. A logistic regression model was trained to classify patients as "progressive" or "non-progressive" using these two variables. The logistic regression model's simplicity and interpretability should facilitate its clinical acceptance. The model was tested on data from an additional 28 patients and found to be 75 % accurate. This accuracy is sufficient to make the predictions clinically useful. It can be used online: http://www.ece.ualberta.ca/~dchalmer/SimpleBracePredictor.html .

Three-dimensional spinal morphology can differentiate between progressive and nonprogressive patients with adolescent idiopathic scoliosis at the initial presentation: a prospective study

STUDY DESIGN

This is a prospective case-control study.

OBJECTIVE

The objective of this study was to compare 3-dimensional (3D) morphological parameters of the spine at the first visit between a nonprogressive (NP) and a progressive (P) group of immature adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Prediction of curve progression remains challenging in AIS at the first visit. Prediction of progression is based on curve type, curve magnitude, and skeletal or chronological age.

METHODS

A prospective cohort of 133 AIS was followed from skeletal immaturity to maturity (mean, 37 mo). The first group was made up of patients with AIS with a minimum 6-degree progression of the major curve between the first and last follow-up (P) (n = 53) and the second group was composed of patients with NP who reached maturity with less than 6-degree progression (n = 81). Computerized measurements were taken on reconstructed 3-dimensional (3D) spine radiographs of the first visit. There were 6 categories of measurements: angle of plane of maximum curvature, Cobb angles (kyphosis, lordosis), 3D wedging (apical vertebra, apical disks), rotation (upper and lower junctional vertebra, apical vertebra, and thoracolumbar junction), torsion, and slenderness (height/width ratio). t tests were also conducted.

RESULTS

There was no statistical difference between the 2 groups for age and initial Cobb angle. P presented significant hypokyphosis, and parameters related to rotation presented significant statistical differences between NP and P (plane of maximal curvature, torsion, and apical axial rotation). Depth slenderness also presented statistical differences.

CONCLUSION

This study confirms that even at the initial visit, 3D morphological differences exist between P and NP AIS. It supports the use of 3D reconstructions of the spine in the initial evaluation of AIS to help predict outcome.