3D analysis of brace treatment in idiopathic scoliosis

The effect of Providence night-time bracing on the sagittal profile in adolescent idiopathic scoliosis

PURPOSE

Adolescent idiopathic scoliosis (AIS) is characterized by coronal scoliosis and often a sagittal hypokyphosis. The effect of bracing on the sagittal profile is not well understood. The aim of this study is to assess the effect of night-time bracing on the sagittal profile in patients with AIS.

METHODS

We retrospectively included AIS patients with a main curve of 25-45° treated with a night-time brace in our institution between 2005 and 2018. Patients with estimated growth potential based on either Risser stage, hand X-rays, or menarchal status were included. Coronal and sagittal radiographic parameters were recorded at both brace- initiation and -termination. Patients were followed until surgery or one year after brace termination. Results were compared to a published cohort of full-time braced patients.

RESULTS

One hundred forty-six patients were included. Maximum thoracic kyphosis (TK) increased 2.5° (± 9.7) (p = 0.003), corresponding to a 3.5-fold relative risk increase post bracing in TK compared to a full-time brace cohort. Twenty-seven percent (n = 36) of the patients were hypokyphotic (T4/T12 < 20°) at brace initiation compared with 19% (n = 26) at brace termination (p = 0.134). All other sagittal parameters remained the same at follow-up. We found no association between progression in the coronal plane and change in sagittal parameters.

CONCLUSION

This is the first study to indicate that night-time bracing of AIS does not induce hypokyphosis. We found a small increase in TK, with a substantially lower risk of developing flat back deformity compared to full-time bracing. The coronal curve progression was not coupled to a change in TK.

3D prediction of curve progression in adolescent idiopathic scoliosis based on biplanar radiological reconstruction

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.

Predictive Parameters for Chêneau Brace Efficacy in Patients with Adolescent Idiopathic Scoliosis

STUDY DESIGN

Retrospective consecutive cohort study.

OBJECTIVE

For patients with mild to moderate adolescent idiopathic scoliosis (AIS), bracing is the standard therapy to prevent progression of deformity. Still, not all patients benefit from treatment in the same way. Therefore, predictive parameters are needed to determine if patients are likely to benefit from brace therapy.

METHODS

Fourty-five AIS patients treated with a Chêneau brace were evaluated retrospectively. Inclusion criteria were based on SRS-criteria. Whole spine X-rays were performed pre-brace, in-brace, and at least 6 months after termination of brace treatment. Gender, age, Risser's sign, vertebral rotation determined by Nash and Moe grading system, in-brace correction and in-brace time per day were parameters evaluated. Treatment success and failure groups were compared to determine possible predictive parameters for successful brace treatment.

RESULTS

Chêneau brace treatment was successful preventing curve progression in 69%. We found significant differences between success and failure group concerning age (14 ± .22 vs 12.4 ± .4; P < .001) and Risser's sign (1.71 ± .16 vs .5 ± .17; P < .001) at beginning of brace treatment. Most significantly, initial in-brace curve correction was correlated with successful outcome after brace treatment (r = .64 (P < .001)).

CONCLUSIONS

As one of few studies adhering to the criteria defined by the Scoliosis Research Society our study shows reliable predictive parameters for Chêneau brace treatment success in patients with AIS. Data shown in this paper will help to differentiate AIS patients who are likely to benefit from adequate bracing therapy from those who could rather benefit from early surgical treatment.

Automated design of nighttime braces for adolescent idiopathic scoliosis with global shape optimization using a patient-specific finite element model

Adolescent idiopathic scoliosis is a complex three-dimensional deformity of the spine, the moderate forms of which require treatment with an orthopedic brace. Existing brace design approaches rely mainly on empirical manual processes, vary considerably depending on the training and expertise of the orthotist, and do not always guarantee biomechanical effectiveness. To address these issues, we propose a new automated design method for creating bespoke nighttime braces requiring virtually no user input in the process. From standard biplanar radiographs and a surface topography torso scan, a personalized finite element model of the patient is created to simulate bracing and the resulting spine growth over the treatment period. Then, the topography of an automatically generated brace is modified and simulated over hundreds of iterations by a clinically driven optimization algorithm aiming to improve brace immediate and long-term effectiveness while respecting safety thresholds. This method was clinically tested on 17 patients prospectively recruited. The optimized braces showed a highly effective immediate correction of the thoracic and lumbar curves (70% and 90% respectively), with no modifications needed to fit the braces onto the patients. In addition, the simulated lumbar lordosis and thoracic apical rotation were improved by 5° ± 3° and 2° ± 3° respectively. Our approach distinguishes from traditional brace design as it relies solely on biomechanically validated models of the patient's digital twin and a design strategy that is entirely abstracted from empirical knowledge. It provides clinicians with an efficient way to create effective braces without relying on lengthy manual processes and variable orthotist expertise to ensure a proper correction of scoliosis.

Predictive analysis of the scoliotic curve using a subject's 3D model

A predictive analysis of the conservative scoliosis treatment is necessary, in which a 3D model of an optimal treatment algorithm is a basic part in the design of a prosthetic corset. Since CAD technology has proven to be very useful in the field of prosthetics and orthotics, we used an open-source software to plan the correction of the scoliotic curve on a virtual model of the subject's torso. The shape of the scoliosis was simplified by means of a directional polygon, which was drawn in a reverse manner depending on the directional arcs of the scoliotic curve. The resulting scoliosis correction, simulated in a predictive analysis, was defined by changing the Cobb angle, eccentricity, and torso height. With the proposed low-cost method of predictive analysis, it is possible to help CPOs to a more accurate and effective design of orthoses and corrective aids and to comprehensively determine the entire treatment procedure.

Outcome of Conservative Therapy of Adolescent Idiopathic Scoliosis (AIS) with Chêneau-Brace

Chêneau-brace (C-Brace) is a potential tool for the treatment of adolescent idiopathic scoliosis (AIS) with a Cobb angle between 20° and 45° for the primary curve. The aim of the present study was (1) to estimate study cohorts with C-brace therapy success and therapy failure and (2) to analyze possible factors that influence the therapy outcome. Seventy-eight patients with AIS were assessed before the initiation of C-brace treatment. Each patient underwent radiography examinations before the brace, in-brace, and at the therapy end. Cobb angle was considered as increased when the value at the end of therapy was increased more than 5° (Δ > 5°), unchanged—when the value was unchanged within ± 5° and decreased- when the value was decreased more than 5° (Δ < −5°). The study cohort was stratified due to curve topography in the thoracic, thoracolumbar, and lumbar scoliosis groups. Global analysis revealed no statistically significant modification of the Cobb angle (Cobb angle pre-brace vs. Cobb angle post-brace: 30.8° ± 8.2 vs. 29.3° ± 15.2, p = 0.26). However, at the end of C-brace therapy, the primary Cobb angle was decreased by more than 5° in 27 patients (35%), unchanged (Δ within the range of ±5°) in 36 patients (46%), and increased more than 5° in 15 patients (19%). Sub-group analysis due to curve topography and skeletal maturity has shown higher rates of brace therapy failure in thoracic curves and in younger patients (Risser grade 0). Patients with higher Cobb angle correction with C-brace had lower rates of therapy failure. The C-brace can be useful for the prevention of scoliotic curve progression in patients with AIS. However, many factors influence the therapy effect.

Does Risser Casting for Adolescent Idiopathic Scoliosis Still Have a Role in the Treatment of Curves Larger Than 40°? A Case Control Study with Bracing

Background: The most common conservative treatment for Adolescent Idiopathic Scoliosis (AIS) is bracing. However, several papers questioned the effectiveness of bracing for curves between 40° and 50° Cobb: the effectiveness in preventing curve progression could be as low as 35%. Seriate casting is considered a standard approach in early onset scoliosis; however, in the setting of AIS, cast treatment is seldom utilized, with only few studies reporting on its effectiveness. Aim of the study: The main aim of the study is to determine whether a seriate casting with Risser casts associated with bracing is more effective in preventing curve progression than bracing alone in curves larger than 40°. Furthermore, the secondary endpoints were: (1) is there a difference in effectiveness of casting between Thoracic (T) and Thoracolumbar/Lumbar (TL/L) curves? (2) Does the ‘in cast’ correction predicts the treatment outcome? (3) What is the effect on thoracic kyphosis of casting? Methods: This is a retrospective monocentric case−control study; through an Institutional Database search we identified all the patients treated at our institution between 1 January 2017 and 31 December 2020, with a diagnosis of AIS, Risser grade between 0 and 4 at the beginning of the treatment, at least one curve above 40° Cobb and treatment with either seriate Risser casting and bracing (Study Group, SG) or bracing alone (Control Group, CG). Standing full spine X-rays in AP and LL are obtained before and after the cast treatment; only AP standing full spine X-rays ‘in-cast’ are obtained for each cast made. Patients were stratified according to the curve behavior at the end of treatment (Risser 5): progression was defined as ≥6° increase in the curve magnitude or fusion needed; stabilization is defined as a change in curve by ±5°; and improvement was defined as ≥6° reduction in the curve. Results: For the final analysis, 55 compliant patients (12 M, 43 F, mean age 13.5 ± 1.6) were included in the SG and 27 (4 M, 23 F, mean age 13.6 ± 1.6) in the CG. Eight (14.5%) patients in the SG failed the conservative treatment while 14 (51.3%) failed in the CG. Consequently, the Relative Risk for progression in the Efficacy Analysis was 1.8 (95% CI 1, 3−2.6, p = 0.001), and the Number Needed to Treat was 2,4. No significant difference was found between the T and TL/L curves concerning the ‘progressive’ endpoint (z-score 0.263, p = 0.79). The mean percentage of ‘in cast’ curve reduction was 40.1 ± 15.2%; no significant correlation was found between the percentage of correction and the outcome (Spearman Correlation Coefficient 0.18). Finally, no significant differences between baseline and end of FU TK were found (32° ± 16.2 vs. 29.6 ± 15.8, p = ns). Discussion: Seriate Risser casting for AIS with larger curves (>40° Cobb) is effective in reducing curve progression when compared with full time bracing alone in treatment compliant patients. The treatment is equally effective in controlling T and TL/L curves; furthermore, a slight but non-significant decrease in TK was observed in patients treated with casting. This type of treatment should be considered for AIS patients who present with large curves to potentially reduce the percentage of surgical cases. Short Abstract: The aim of the study is to determine whether seriate Risser casting associated with bracing is more effective in preventing curve progression than bracing alone in curves larger than 40°. This is a retrospective monocentric case−control study; we identified all the patients treated at our institution with a diagnosis of AIS, Risser grade 0−4 at the beginning of the treatment, at least one curve above 40° Cobb (35° if treated with bracing alone) and treatment with either seriate Risser casting and bracing (Study Group, SG) or bracing alone (Control Group, CG). Fifty-five patients (12 M, 43 F, mean age 13.5 ± 1.6) were included in the SG and 30 (5 M, 25 F, mean age 13.9 ± 1.7) in the CG. Eight (14,5%) patients in the SG failed the conservative treatment while fifteen (50%) failed in the CG. Consequently, the Relative Risk for progression in the Efficacy Analysis was 1.8 (95% CI 1.3−2.6, p = 0.001), and the Number Needed to Treat was 2,4. Seriate Risser casting for AIS with larger curves (>40°) is effective in reducing curve progression when compared with full time bracing alone. This type of treatment should be considered for AIS patients who present with large curves.

Do the three-dimensional parameters of brace-wearing patients with AIS change when transitioning from standing to sitting position? A preliminary study on Lenke I

Background

Bracing is the most common conservative treatment for preventing the progression of adolescent idiopathic scoliosis (AIS) in patients with a curve of 25°–40°. X-ray examinations are traditionally performed in the standing position. However, school-age teenagers may take more time to sit. Thus far, little is known about three-dimensional (3D) correction in the sitting position. Hence, this study aimed to determine the effects of standing and sitting positions on 3D parameters during brace correction.

Methods

We evaluated a single-center cohort of patients receiving conservative treatment for thoracic curvature (32 patients with AIS with a Lenke I curve). The 3D parameters of their standing and sitting positions were analyzed using the EOS imaging system during their first visit and after bracing.

Results

At the patients’ first visit, sagittal plane parameters such as thoracic kyphosis (TK), lumbar lordosis (LL), and sacral slope decreased when transitioning from the standing position to the sitting position (standing 29° ± 6°, 42° ± 8°, and 42° ± 8° vs. sitting 22° ± 5°, 27° ± 6°, and 24° ± 4°; p < 0.001), whereas pelvic tilt (PT) increased and sagittal vertical axis shifted forward (standing 9° ± 6° and 1.6 ± 2.7 cm vs. sitting 24° ± 4° and 3.8 ± 2.3 cm; p < 0.001). After bracing, TK and LL decreased slightly (from 29° ± 6° and 42° ± 8° to 23° ± 3° and 38° ± 6°; p < 0.001), whereas the thoracolumbar junction (TLJ) value increased (from 3° ± 3° to 11° ± 3°; p < 0.001). When transitioning to the sitting position, similar characteristics were observed during the first visit, except for a subtle increase in the TLJ and PT values (standing 11° ± 3° and 9° ± 4° vs. sitting 14° ± 3° and 28° ± 4°; p < 0.001). Moreover, the coronal and axial parameters at different positions measured at the same time showed no significant change.

Conclusions

In brace-wearing patients with thoracic scoliosis, compensatory sagittal plane straightening may be observed with a slight increase in thoracolumbar kyphosis, particularly when transitioning from the standing position to the sitting position, due to posterior rotation of the pelvis. Our results highlight that sagittal alignment in AIS with brace treatment is not completely analyzed with only standing X-Ray.

Trial registration

The study protocol was registered with the Chinese Clinical Trial Registry (ChiCTR1800018310).

Thoracic kyphosis in light of lumbosacral alignment in thoracic adolescent idiopathic scoliosis: recognition of thoracic hypokyphosis and therapeutic implications

BACKGROUND

The uniqueness of spinal sagittal alignment in thoracic adolescent idiopathic scoliosis (AIS), for example, the drastically smaller thoracic kyphosis seen in some patients, has been recognized but not yet fully understood. The purpose of this study was to clarify the characteristics of sagittal alignment of thoracic AIS and to determine the contributing factors.

METHODS

Whole spine radiographs of 83 thoracic AIS patients (73 females) were analyzed. The measured radiographic parameters were the Cobb angle of thoracic scoliosis, thoracic kyphosis (TK), lumbar lordosis (LL), C7 sagittal vertical axis (C7 SVA), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS). Additionally, max-LL, which was defined as the maximum lordosis angle from the S1 endplate, the inflection point between thoracic kyphosis and lumbar lordosis, and the SVA of the inflection point (IP SVA) were measured. The factors significantly related to a decrease in TK were assessed by stepwise logistic regression analysis. In addition, cluster analysis was performed to classify the global sagittal alignment.

RESULTS

The significant factors for a decrease in TK were an increase in SS (p = 0.0003, [OR]: 1.16) and a decrease in max-LL (p = 0.0005, [OR]: 0.89). According to the cluster analysis, the global sagittal alignment was categorized into the following three types: Type 1 (low SS, low max-LL, n = 28); Type 2 (high SS, low max-LL, n = 22); and Type 3 (high SS, high max-LL, n = 33).

CONCLUSIONS

In thoracic AIS, a decreased TK corresponded to an increased SS or a decreased max-LL. The sagittal alignment of thoracic AIS patients could be classified into three types based on SS and max-LL. One of these three types includes the unique sagittal profile of very small TK.

A Novel Classification of 3D Rib Cage Deformity in Subjects With Adolescent Idiopathic Scoliosis

STUDY DESIGN

This was a multicentric cross-sectional descriptive study.

OBJECTIVE

To analyze patterns of 3D rib cage deformity in subjects with adolescent idiopathic scoliosis (AIS) and their relationship with the spinal deformity.

SUMMARY OF BACKGROUND DATA

Subjects with AIS present with rib cage deformity that can affect respiratory functions. The 3D rib cage deformities in AIS and their relationship to the spinal deformity are still unelucidated.

METHODS

A total of 200 AIS and 71 controls underwent low-dose biplanar x-rays and had their spine and rib cage reconstructed in 3-dimensional (D). Classic spinopelvic parameters were calculated in 3D and: rib cage gibbosity, thickness, width, volume and volumetric spinal penetration index (VSPI). Subjects with AIS were classified as: group I with mild rib cage deformity (n=88), group II with severe rib cage deformity (n=112) subgrouped into IIa (high gibbosity, n=48), IIb (high VSPI, n=48), and IIc (both high gibbosity and VSPI, n=16).

RESULTS

Groups IIa and IIb had a higher Cobb angle (33 vs. 54 degrees and 46 degrees, respectively) and torsion index (11 vs. 14 degrees and 13 degrees, respectively) than group I. Group IIb showed more severe hypokyphosis (IIb=21 degrees; IIa=33 degrees; I=36 degrees; control=42 degrees) with a reduced rib cage volume (IIb=4731 cm3; IIa=4985 cm3; I=5257 cm3; control=5254 cm3) and thickness (IIb=135 mm; IIa=148 mm; I=144 mm; control=144 mm). Group IIa showed an increasingly large local gibbosity descending from proximal to distal levels and did not follow the axial rotation of the spine. Group IIc showed characteristics of both groups IIa and IIb.

CONCLUSIONS

This new classification of 3D rib cage deformity in AIS shows that the management of cases with high VSPI (groups IIb and IIc) should focus on restoring as much kyphosis as possible to avoid respiratory repercussions. Treatment indications in groups I and IIa would follow the consensual basic principles reported in the literature regarding bracing and surgery.

Influence of Chêneau-Brace Therapy on Lumbar and Thoracic Spine and Its Interdependency with Cervical Spine Alignment in Patients with Adolescent Idiopathic Scoliosis (AIS)

Chêneau-brace is an effective therapy tool for treatment in adolescent idiopathic scoliosis (AIS). Data on potential interdependent changes of the sagittal profile including the cervical spine are still sparse. The purpose of this study was to evaluate in-brace changes of the thoracic and lumbar spine and their influence on the pelvis and the cervical spine and apical vertebral rotation was reported. Ninety-three patients with AIS undergoing Chêneau-bracing were included. Patients were stratified by lumbar, thoracic and global spine alignment into normolordotic vs. hyperlordotic or normokyphotic vs. hypokyphotic or anteriorly aligned vs. posteriorly aligned groups. The coronal Cobb angle was significantly decreased in all groups indicating good correction while in-brace therapy. Sagittally, in-brace treatment led to significant flattening of lumbar lordosis (LL) in all stratified groups. Thoracic kyphosis (TK) was significantly flattened in the normokyphotic group, but no TK changes were noticed in the hypokyphotic group. Pelvic tilt (PT) stayed unchanged during the in-brace therapy. Chêneau-brace showed marginal changes in the lower cervical spine but had no influence on the upper cervical spine. The apical vertebral axis in primary and secondary curves was unchanged during the first radiological follow-up. Results from this study contribute to better understanding of initial spine behavior in sagittal and axial plane in the context of bracing.

Finite element assessment of a disc-replacement implant for treating scoliotic deformity

BACKGROUND

Bracing and spinal fusion surgery have long been the primary methods for idiopathic scoliosis correction; however, there exist multiple limitations with both techniques. Growth modulation techniques have recently been attempted, but are typically performed across multiple vertebral elements. The aim of this study was to quantify the corrective abilities of a dual-angled, wedge shaped, rigid disc implant designed to correct spinal deformity.

METHODS

The 3D spinal geometry of four patients was reconstructed using calibrated radiographs, from which personal finite element models were created. Coronal and sagittal Cobb angles and axial stress distribution were calculated pre- and post- simulation of device implantation at the apical vertebral element.

FINDINGS

Insertion of a rigid wedged implant resulted in up to 90.1% coronal correction with kyphotic normalization, and reduced axial stress differential within adjacent vertebrae by up to 83.3%. This correction in axial stress differential was seen to propagate to subjacent vertebrae in both rostral and caudal directions. Insertion of two implants yielded greater correction with respect to all three measures.

INTERPRETATION

Local Cobb angle correction, increased kyphotic angle, and a decrease in axial stress differential with adjacent and subjacent vertebral levels demonstrate a potential for deformity correction from within the disc space. The decrease in axial stress differential demonstrates a capacity for growth modulation and reversal of the Heuter-Volkmann principle. Based on qualitative views of spinal shape following device implantation, the wedged implant proved more efficacious in correcting single thoracic curves than double major curves.

Thoracoscopic Vertebral Body Tethering for Adolescent Idiopathic Scoliosis: A Minimum of 2 Years' Results of 21 Patients

BACKGROUND

Anterior vertebral body tethering (VBT) is a growth modulating and fusionless treatment option that is considered as a new promising method for the management of adolescent idiopathic scoliosis (AIS). This prospective cohort study aimed to present the minimum 2-year results of anterior VBT applied to 21 skeletally immature patients with AIS.

METHODS

Twenty-one skeletally immature patients with a diagnosis of AIS were included. A decision to proceed with surgery was established after the detection of curve progression despite the brace (>40 degrees) with a minimum curve flexibility of 30%.

RESULTS

Patients had an average age of 11.1 and an average follow-up period of 27.4 months. All patients underwent thoracoscopic placement of thoracic screws, from the convex side of curves. An average of 7.1 levels of tethering was undertaken. Average preoperative major thoracic curve magnitudes improved from 48.2 to 16 degrees on the first erect postoperative x-ray, and to 10 degrees at the last follow-up (P<0.001). Immediate postoperatively, 1 case with chylothorax was detected and treated conservatively, and another case with tether breakage was detected at the third postoperative year and replaced thoracoscopically. No other major complication was acquired.

CONCLUSIONS

Anterior VBT as a growth modulating treatment option by allowing the correction of the scoliotic deformity and preserving coronal balance was detected to be a safe and effective option for the surgical treatment of AIS in skeletally immature patients, if applied under strict inclusion criteria. VBT by allowing preservation of spinal segmental motion is yielding promising radiographic results without causing any major complications.

LEVEL OF EVIDENCE

Level IV.

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.

Braces Designed Using CAD/CAM Combined or Not With Finite Element Modeling Lead to Effective Treatment and Quality of Life After 2 Years: A Randomized Controlled Trial

STUDY DESIGN

Single-center prospective randomized controlled trial.

OBJECTIVE

The aim of this study was to assess the computer-aided design/manufacturing (CAD/CAM) brace design approach, with and without added finite element modeling (FEM) simulations, after 2 years in terms of clinical outcomes, 3D correction, compliance, and quality of life (QoL).

SUMMARY OF BACKGROUND DATA

.: Previous studies demonstrated that braces designed using a combination of CAD/CAM and FEM induced promising in-brace corrections, were lighter, thinner, and covered less trunk surface. Yet, their long-term impact on treatment quality has not been evaluated.

METHODS

One-hundred twenty adolescent idiopathic scoliosis patients were recruited following Scoliosis Research Society standardized criteria for brace treatment; 61 patients in the first subgroup (CAD) were given braces designed using CAD/CAM; 59 in the second subgroup (CAD-FEM) received braces additionally simulated and refined using a patient-specific FEM built from 3D reconstructions of the spine, rib cage and pelvis. Main thoracic (MT) and thoraco-lumbar/lumbar (TL/L) Cobb angles, sagittal curves, and apical rotations were compared at the initial visit and after 2 years. Patient compliance and QoL were tracked respectively by using embedded temperature sensors and SRS-22r questionnaires.

RESULTS

Forty-four patients with CAD-FEM braces and 50 with CAD braces completed the study. Average in-brace correction was 9° MT (8° CAD-FEM, 10° CAD, P = 0.054) and 12° TL/L (same for both subgroups, P = 0.91). Out-of-brace 2-year progression from initial deformity was <4° for all 3D measurements. Sixty-six percent of all cases (30 CAD-FEM, 35 CAD) met the ≤5° curve progression criterion, 83% (38 CAD-FEM, 43 CAD) stayed <45°, and 6% (5 CAD-FEM, 1 CAD) underwent fusion surgery. 3D correction, compliance, and QoL were not significantly different between both subgroups (P > 0.05).

CONCLUSION

After 2 years, patients with braces designed using CAD/CAM with/without FEM had satisfying clinical outcomes (compared to the BrAIST study), 3D corrections, compliance and QoL. A more comprehensive optimization of brace treatment remains to be accomplished.

LEVEL OF EVIDENCE

2.

Towards a predictive simulation of brace action in adolescent idiopathic scoliosis

Bracing is the most common treatment to stop the progression of adolescent idiopathic scoliosis. Finite element modeling could help improve brace design, but model validation is still a challenge. In this work, the clinical relevance of a predictive and subject-specific model for bracing was evaluated in forty-six AIS patients. The model reproduces brace action and the patient's spinopelvic adjustments to keep balance. The model simulated 70% or more patients with geometrical parameters within a preselected tolerance level. Although the model simulation of the sagittal plane could be improved, the approach is promising for a realistic and predictive simulation of brace action.

Alterations of sagittal alignment and thoracic cage parameters after long-term bracing in adolescents with idiopathic scoliosis

BACKGROUND

Sagittal alignment and thoracic cage parameters are correlated with the surgery success rate and life quality of adolescents with idiopathic scoliosis (AIS). However, the effects of the long-term bracing on sagittal and thoracic cage parameters have not been clearly recognized.

HYPOTHESIS

Long-term brace treatment could compromise sagittal balance and thoracic development in patients with AIS.

PATIENTS AND METHODS

Two hundred and seventy-five patients with AIS were included in this study. The radiographs when AIS was diagnosed and 2 years after Chêneau bracing treatment were collected. Sagittal, cervical, pelvic, and thoracic cage parameters were evaluated. In addition, 32 patients finishing brace treatment with complete radiograph data were selected from included 275 patients and the data of CL, TK and LL at five different time points was collected.

RESULTS

CL (average: from 14.13° to 8.94°, p=0.012), TK (average: from 24.35° to 19.02°, p=0.001) and LL (average: from 38.44° to 32.13°, p=0.004) underwent observably decline after two-year brace treatment. No statistically significant alteration of pelvic parameters was shown. The vertical parameters of thoracic cage including T1-12 height, left and right thorax height and thoracic transverse diameter increased significantly. Thoracic anteroposterior diameter at the T7 vertebral level (average: from 11.49 to 10.57cm, p=0.001) and diaphragm level (average: from 11.89 to 10.74cm, p=0.001) decreased significantly after bracing.

DISCUSSION

CL, TK and LL decreased after long-term bracing treatment, which lead to the aggravation of "flat back" in AIS patients. In addition, the thoracic anteroposterior diameters declined after two-year bracing, which may result from reduced TK and contribute to further pulmonary function impairment.

LEVEL OF EVIDENCE

IV.

Underarm bracing for adolescent idiopathic scoliosis leads to flatback deformity

Aims

The aim of this study was to determine the influence of pelvic parameters on the tendency of patients with adolescent idiopathic scoliosis (AIS) to develop flatback deformity (thoracic hypokyphosis and lumbar hypolordosis) and its effect on quality-of-life outcomes.

Patients and Methods

This was a radiological study of 265 patients recruited for Boston bracing between December 2008 and December 2013. Posteroanterior and lateral radiographs were obtained before, immediately after, and two-years after completion of bracing. Measurements of coronal and sagittal Cobb angles, coronal balance, sagittal vertical axis, and pelvic parameters were made. The refined 22-item Scoliosis Research Society (SRS-22r) questionnaire was recorded. Association between independent factors and outcomes of postbracing ≥ 6° kyphotic changes in the thoracic spine and ≥ 6° lordotic changes in the lumbar spine were tested using likelihood ratio chi-squared test and univariable logistic regression. Multivariable logistic regression models were then generated for both outcomes with odds ratios (ORs), and with SRS-22r scores.

Results

Reduced T5-12 kyphosis (mean -4.3° (sd 8.2); p < 0.001), maximum thoracic kyphosis (mean -4.3° (sd 9.3); p < 0.001), and lumbar lordosis (mean -5.6° (sd 12.0); p < 0.001) were observed after bracing treatment. Increasing prebrace maximum kyphosis (OR 1.133) and lumbar lordosis (OR 0.92) was associated with postbracing hypokyphotic change. Prebrace sagittal vertical axis (OR 0.975), prebrace sacral slope (OR 1.127), prebrace pelvic tilt (OR 0.940), and change in maximum thoracic kyphosis (OR 0.878) were predictors for lumbar hypolordotic changes. There were no relationships between coronal deformity, thoracic kyphosis, or lumbar lordosis with SRS-22r scores.

Conclusion

Brace treatment leads to flatback deformity with thoracic hypokyphosis and lumbar hypolordosis. Changes in the thoracic spine are associated with similar changes in the lumbar spine. Increased sacral slope, reduced pelvic tilt, and pelvic incidence are associated with reduced lordosis in the lumbar spine after bracing. Nevertheless, these sagittal parameter changes do not appear to be associated with worse quality of life. Cite this article: Bone Joint J 2019;101-B:1370–1378.

Three-Dimensional Analysis of Initial Brace Correction in the Setting of Adolescent Idiopathic Scoliosis

The three-dimensional nature of adolescent idiopathic scoliosis (AIS) necessitates a tridimensional assessment and management. Bracing constitutes the mainstay conservative treatment for mild adolescent idiopathic scoliosis. In the literature hitherto, there has been uncertainty regarding the behavior of the spine, pelvis, and vertebral orientations in the context of bracing, especially in the transverse plane. This poses a challenge to healthcare providers, patients, and their families, as brace treatment, although not as invasive as surgery, is laden with medical and psychological complications and could be considered traumatizing. Hence, a thorough understanding of initial three-dimensional spinal behavior in the context of bracing is important. The purpose of this retrospective study was to investigate the immediate 3D impact of Chêneau-type brace. Thirty-eight patients with AIS undergoing Chêneau-type bracing were included. Patients were stratified according to their structural curve topography into thoracic, thoracolumbar, and lumbar groups. 3D reconstruction of the spine using a dedicated biplanar stereoradiography software with and without the brace was performed. The examined anthropometric radiographic measures were pre- to in-brace variations and differences of spinopelvic parameters and vertebral orientations in the coronal, sagittal, and transverse planes. The complex impact of the Chêneau-type brace on different curves in three planes was delineated. In the coronal plane, the Cobb angle was significantly decreased in all types of curves, and the coronal tilt correction was concentrated in specific segments. The impact of the brace in this study on the sagittal profile was variable, including the loss of thoracic kyphosis and lumbar lordosis. In the transverse plane, an axial vertebral rotation change and detorsion above the apex occurred in the thoracolumbar curves. The results from this exploratory study could shed some light on the initial 3D spinal behavior in the context of bracing and may be of beneficial for treating physicians and brace makers.

Quality of life and patient satisfaction in bracing treatment of adolescent idiopathic scoliosis

BACKGROUND

Bracing is used as a valid non-surgical treatment for adolescent idiopathic scoliosis (AIS) to avoid progression of the deformity and thereby surgery. The effect of bracing treatment on quality of life of patients with AIS has been a topic of interest in the international literature. The aim of this study was to evaluate the quality of life and patient satisfaction during bracing treatment for AIS of a pediatric hospital.

MATERIAL AND METHOD

We assessed a total of 43 non-consecutive female patients (mean age at questionnaire, 13 years and 1 month and 10 years and 8 months to 14 years and 5 months; mean period of usage of brace, 1 year and 7 months), with adolescent idiopathic scoliosis (AIS), older than 10 years of age until skeletal maturity, with a Risser sign less than 3 and scoliosis between 20 and 45°, treated with thoracolumbosacral orthosis (TLSO) for a period longer than 6 months, and without other comorbidities or previous surgeries, were evaluated. The patients were administered a previously validated to Spanish questionnaire on quality of life (Brace Questionnaire (BrQ); Grivas TB et al.). BrQ is a validated tool and is considered a disease-specific instrument; its score ranges from 20 to 100 points, and higher BrQ scores are associated with better quality of life.

RESULTS

The patients reported using the brace for a mean of 17.6 h daily and for a mean period of 1 year and 7 months at the time of the study. Overall, 72% of the study population reported to be in some way psychologically affected by the brace wearing, 56% felt their basic motor activities were affected, 54% felt socialization with their environment was affected, 46% considered their quality of life deteriorated due to pain, and 40% reported conflicts in the school environment.

CONCLUSION

Patients with AIS treated with bracing reported a negative impact (53.5% overall) on quality of life and treatment satisfaction in terms of psychological, motor, social, and school environment aspects. An interdisciplinary approach would be important for the integrated psychosocial care of these patients.

[The advantages of 3D imagery in diagnosing and supervising children's and teenagers' scoliosis]

Scoliosis is an abnormal curvature of the spine. One or several curves of more than 10 degrees in the frontal plane can be seen with the rotation of vertebrae in the axial plane, which modifies sagittal curves. In addition to esthetic harm, the morbidity of a scoliosis depends on the extent of the deformation. Treatment, whether it be orthopedic or surgical, is aggressive and never completely cures the condition. At best the deformation will be stabilized at the end of growth. Therefore, it is essential to detect any slight curve and quickly identify any potential progressive form in order to treat it. Visualization of scoliosis in 3D through spine modeling has several advantages at each stage of care. First, with slight curvatures, 3D modeling allows the medical staff to confirm the scoliosis by showing the modification in the three different planes. All curvatures will not progress. Orthopedic treatment is constraining and expensive; only progressive forms will receive it. When the curvature is slight and does not need immediate treatment, 3D modeling at each successive check-up will help detect any sign of likely progression quickly and reliably. Moreover, the medical observation of corset treatment and the preoperative work-up are improved because all 3D parameters of the deformation are accessible. The need for 3D modeling for scoliosis has been known for a long time, but no tool allowing a vertical study with a low level of radiation was available. The EOS imagery system meets these criteria through an optimal analysis of deformations caused by scoliosis.

3D correction of AIS in braces designed using CAD/CAM and FEM: a randomized controlled trial

Background

Recent studies showed that finite element model (FEM) combined to CAD/CAM improves the design of braces for the conservative treatment of adolescent idiopathic scoliosis (AIS), using 2D measurements from in-brace radiographs. We aim to assess the immediate effectiveness on curve correction in all three planes of braces designed using CAD/CAM and numerical simulation compared to braces designed with CAD/CAM only.

Methods

SRS standardized criteria for bracing were followed to recruit 48 AIS patients who were randomized into two groups. For both groups, 3D reconstructions of the spine and patient’s torso, respectively built from bi-planar radiographs and surface topography, were obtained and braces were designed using the CAD/CAM approach. For the test group, 3D reconstructions of the spine and patient’s torso were additionally used to generate a personalized FEM to simulate and iteratively improve the brace design with the objective of curve correction maximization in three planes and brace material minimization.

Results

For the control group (CtrlBraces), average Cobb angle prior to bracing was 29° (thoracic, T) and 25° (lumbar, L) with the planes of maximal curvature (PMC) respectively oriented at 63° and 57° on average with respect to the sagittal plane. Average apical axial rotation prior to bracing was 7° (T) and 9° (L). For the test group (FEMBraces), initial Cobb angles were 33° (T) and 28° (L) with the PMC at 68° (T) and 56° (L) and average apical axial rotation prior to bracing at 9° (T and L). On average, FEMBraces were 50% thinner and had 20% less covering surface than CtrlBraces while reducing T and L curves by 47 and 48%, respectively, compared to 25 and 26% for CtrlBraces. FEMBraces corrected apical axial rotation by 46% compared to 30% for CtrlBraces.

Conclusion

The combination of numerical simulation and CAD/CAM approach allowed designing more efficient braces in all three planes, with the advantages of being lighter than standard CAD/CAM braces. Bracing in AIS may be improved in 3D by the use of this simulation platform. This study is ongoing to recruit more cases and to analyze the long-term effect of bracing.

Trial registration

ClinicalTrials.gov, NCT02285621

Early outcomes of spinal growth tethering for idiopathic scoliosis with a novel device: a prospective study with 2 years of follow-up

QUESTIONS/PURPOSES

Adolescent idiopathic scoliosis is a 3D spine deformity that worsens during the whole growth. New methods for spinal growth modulation with flexible spinal implants have been described to avoid progression of the deformity during growth spurt. The main limitations are that no specific ancillaries and devices are available, which makes the surgery technically demanding.

METHODS

We have developed a new method of spinal growth tethering using minimal invasive videothoracoscopic approach. Fixation is performed with staples and synthetic ligament on the lateral aspect of vertebral bodies on main curvature convexity. Patients with progressive thoracic idiopathic scoliosis despite the brace treatment were included. The clinical and radiological examinations were compared before and 2 years after surgery.

RESULTS

Six patients with flexible thoracic curves with a mean age 11.2 ± 1.2 years and a mean Cobb angle 45° ± 10° (35-60) were operated. All were skeletally immature. At last follow-up, the Cobb angle was stable. None of the patient underwent fusion.

CONCLUSIONS

The procedure allowed a stabilization of the deformity during growth spurt. Validated devices and further studies with longer term follow-up are needed to confirm the efficiency of this technique. This small cohort of patients is a source of reflection for further medical devices developments.

LEVEL OF EVIDENCE

Level 4 case series comparing to not randomized studies.

Efficacy of nighttime brace in preventing progression of idiopathic scoliosis of less than 25°

INTRODUCTION

The objective of the present study was to assess, at skeletal maturity, the efficacy of non-operative treatment by isolated nighttime brace in the prevention of progression of progressive idiopathic scoliosis of less than 25°.

HYPOTHESIS

Isolated nighttime brace treatment is effective in the prevention of progression of mild progressive idiopathic scoliosis (Cobb<25°).

MATERIAL AND METHODS

A single-center retrospective study included 142 patients managed by nighttime brace for progressive idiopathic scoliosis with Cobb angle<25°, with assessment at skeletal maturity. Mean Cobb angle at start of treatment was 15.5° (range, 10-25°). Mean values for Cobb angle and sagittal parameters before treatment and at skeletal maturity were compared on Student t-test. Change in Cobb angle over time was also analyzed.

RESULTS

Mean Cobb angle at skeletal maturity was 16.3°, showing significant increase over baseline (15.5°; P=0.04), although the difference was less than the uncertainty of measurement (±6°). In baseline Risser 0 or 1, mean change in Cobb angle at skeletal maturity (16.2°) was not significant (P=0.1). Cobb angle diminished in 26 cases (18%), increased in 24 (17%) and was unchanged in 92 (65%).

CONCLUSION

The present study confirmed the efficacy of non-operative treatment by nighttime brace in mild progressive idiopathic scoliosis (<25°) in a large majority of cases. A nighttime brace thus seems to be an effective option for the treatment of adolescent scoliosis, ensuring a safe curve of around 20°.

LEVEL OF EVIDENCE

Level IV, retrospective study.

Radiation dose of digital radiography (DR) versus micro-dose x-ray (EOS) on patients with adolescent idiopathic scoliosis: 2016 SOSORT- IRSSD "John Sevastic Award" Winner in Imaging Research

BACKGROUND

Patients with adolescent idiopathic scoliosis (AIS) frequently receive x-ray imaging at diagnosis and subsequent follow monitoring. The ionizing radiation exposure has accumulated through their development stage and the effect of radiation to this young vulnerable group of patients is uncertain. To achieve the ALARA (as low as reasonably achievable) concept of radiation dose in medical imaging, a slot-scanning x-ray technique by the EOS system has been adopted and the radiation dose using micro-dose protocol was compared with the standard digital radiography on patients with AIS.

METHODS

Ninety-nine participants with AIS underwent micro-dose EOS and 33 underwent standard digital radiography (DR) for imaging of the whole spine. Entrance-skin dose was measured using thermoluminescent dosimeters (TLD) at three regions (i.e. dorsal sites at the level of sternal notch, nipple line, symphysis pubis). Effective dose and organ dose were calculated by simulation using PCXMC 2.0. Data from two x-ray systems were compared using independent-samples t-test and significance level at 0.05. All TLD measurements were conducted on PA projection only. Image quality was also assessed by two raters using Cobb angle measurement and a set of imaging parameters for optimization purposes.

RESULTS

Entrance-skin dose from micro-dose EOS system was 5.9-27.0 times lower at various regions compared with standard DR. The calculated effective dose was 2.6 ± 0.5 (μSv) and 67.5 ± 23.3 (μSv) from micro-dose and standard DR, respectively. The reduction in the micro-dose was approximately 26 times. Organ doses at thyroid, lung and gonad regions were significantly lower in micro-dose (p < 0.001). Data were further compared within the different gender groups. Females received significantly higher (p < 0.001) organ dose at ovaries compared to the testes in males. Patients with AIS received approximately 16-34 times lesser organ dose from micro-dose x-ray as compared with the standard DR. There was no significant difference in overall rating of imaging quality between EOS and DR. Micro-dose protocol provided enough quality to perform consistent measurement on Cobb angle.

CONCLUSIONS

Entrance-skin dose, effective dose and organ dose were significantly reduced in micro-dose x-ray. The effective dose of a single micro-dose x-ray (2.6 μSv) was less than a day of background radiation. As AIS patients require periodic x-ray follow up for surveillance of curve progression, clinical use of micro-dose x-ray system is beneficial for these young patients to reduce the intake of ionizing radiation.

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.

The three dimensional analysis of the Sforzesco brace correction

Background

Scoliosis is a three dimensional deformity, and brace correction should be 3D too. There is a lack of knowledge of the effect of braces, particularly in the sagittal and transverse plane. The aim of this study is to analyse the Sforzesco Brace correction, through all the parameters provided by Eos 3D imaging system.

Method

Design: This is a cross sectional study from a prospective database started in March 2003.

Participants: 16 AIS girls (mean age 14.01) in Sforzesco brace treatment, with EOS x-rays, at start, in brace after 1 month and out of brace after the first 4 months of treatment. Outcome measures: All the parameters and the Torsio-Index obtained from 3D Eos System, in and out of brace, in the three planes. Statistical analysis: the variability of the parameters and the mean differences were analyzed and compared using paired T test. ANOVA was used for multiple comparisons. Critical P value was set at 0.05.

Results

In the comparison of in-brace vs start of treatment, the mean Cobb angle changed significantly from 36.44 +/− 4 to 28.99 + −3.9° (p = 0.01). Significant changes in all the sagittal parameters were found (p = 0.02). In the axial plane, the Torsio Index changed significantly in-brace for thoracolumbar and lumbar curves (P < 0.05). The analysis of the single vertebral tilt demonstrated that the effect of the brace is mostly concentrated at specific segments: T4-T5, T10-T12, L1 and L5 in the axial plane and T3-T6 and T10-L1 in the frontal plane.

Conclusion

The Sforzesco brace mostly modifies the middle of the spine and preserves the sagittal balance. The single vertebral orientation in each plane should be considered together with the typically used values to assess brace effect.

The use of a photogrammetric method for the three-dimensional evaluation of spinal correction in scoliosis

PURPOSE

Clinical parameters, characterizing the spinal deformations due to scoliosis, are still directly measured on the spinal curve plane projections.

METHODS

A 3D spinal curve has been reconstructed from its two projections, using photogrammetric techniques. Each spinal curve is a compound of several plane regions, where it is purely flexed, and short zones of connection, where abduction and axial rotation components are concentrated. All spinal curves are represented as linear chains of regional planes articulated together. The regional plane is represented by a triangle, where one summit corresponds to the point of maximum offset. The set of weight forces, representing pelvis and spine, forms a bundle of vertical forces. The dispersion of the bundle illustrates the postural stability of patients.

RESULTS AND CONCLUSIONS

The first objective was to numerically describe the changes of the 3D spinal feature, due to the correcting treatment. Changes are calculated from the comparison between 3D radiologic situations, between before and after treatment. The second objective was to determine the direction of the external force, which would be the most efficient for correcting the patient set spine/rib cage. A mild mechanical analysis is proposed, for representing the transit of the external force, from rib cage to thoracic regional plane.

Adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is the most common form of structural spinal deformities that have a radiological lateral Cobb angle - a measure of spinal curvature - of ≥10(°). AIS affects between 1% and 4% of adolescents in the early stages of puberty and is more common in young women than in young men. The condition occurs in otherwise healthy individuals and currently has no recognizable cause. In the past few decades, considerable progress has been made towards understanding the clinical patterns and the three-dimensional pathoanatomy of AIS. Advances in biomechanics and technology and their clinical application, supported by limited evidence-based research, have led to improvements in the safety and outcomes of surgical and non-surgical treatments. However, the definite aetiology and aetiopathogenetic mechanisms that underlie AIS are still unclear. Thus, at present, both the prevention of AIS and the treatment of its direct underlying cause are not possible.

Long-term effects of the Chêneau brace on coronal and sagittal alignment in adolescent idiopathic scoliosis

OBJECT

The aim of the present study was to retrospectively evaluate progressive correction of coronal and sagittal alignment and pelvic parameters in patients treated with a Chêneau brace.

METHODS

Thirty-two patients with adolescent idiopathic scoliosis (AIS) were assessed before initiation of bracing treatment and at the final follow-up. Each patient underwent radiological examinations, and coronal, sagittal, and pelvic parameters were measured.

RESULTS

No statistically significant modification of the Cobb angle was noted. The pelvic incidence remained unchanged in 59% of the cases and increased in 28% of the cases. The sacral slope decreased in 34% of the cases but remained unchanged in 50%. Thoracic kyphosis and lumbar lordosis were significantly decreased, whereas the sagittal vertical axis was significantly increased from a mean of -44.0 to -30.2 mm (p = 0.02). The mean pelvic tilt increased significantly from 4.5° to 8.3° (p = 0.002).

CONCLUSIONS

The Chêneau brace can be useful for preventing curvature progression in patients with AIS. However, the results of this study reveal high variability in the effect of brace treatment on sagittal and pelvic alignment. Treatment with the Chêneau brace may also influence sagittal global balance.

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 .

Evaluation of a Patient-Specific Finite-Element Model to Simulate Conservative Treatment in Adolescent Idiopathic Scoliosis

STUDY DESIGN

Retrospective validation study.

OBJECTIVES

To propose a method to evaluate, from a clinical standpoint, the ability of a finite-element model (FEM) of the trunk to simulate orthotic correction of spinal deformity and to apply it to validate a previously described FEM.

SUMMARY OF BACKGROUND DATA

Several FEMs of the scoliotic spine have been described in the literature. These models can prove useful in understanding the mechanisms of scoliosis progression and in optimizing its treatment, but their validation has often been lacking or incomplete.

METHODS

Three-dimensional (3D) geometries of 10 patients before and during conservative treatment were reconstructed from biplanar radiographs. The effect of bracing was simulated by modeling displacements induced by the brace pads. Simulated clinical indices (Cobb angle, T1-T12 and T4-T12 kyphosis, L1-L5 lordosis, apical vertebral rotation, torsion, rib hump) and vertebral orientations and positions were compared to those measured in the patients' 3D geometries.

RESULTS

Errors in clinical indices were of the same order of magnitude as the uncertainties due to 3D reconstruction; for instance, Cobb angle was simulated with a root mean square error of 5.7°, and rib hump error was 5.6°. Vertebral orientation was simulated with a root mean square error of 4.8° and vertebral position with an error of 2.5 mm.

CONCLUSIONS

The methodology proposed here allowed in-depth evaluation of subject-specific simulations, confirming that FEMs of the trunk have the potential to accurately simulate brace action. These promising results provide a basis for ongoing 3D model development, toward the design of more efficient orthoses.