Bracing in adolescent idiopathic scoliosis

Discontinuation of brace treatment in adolescent idiopathic scoliosis (AIS): a scoping review

PURPOSE

Brace treatment for adolescent idiopathic scoliosis (AIS) is usually prescribed for 20-40° curves in patients with growth potential. The aim is to reduce the risk of curve progression during growth and to avoid the curve reaching a surgical threshold. Having as small a curve as possible at skeletal maturity will reduce the risk of curve progression during adult life. While evidence exists for brace treatment in AIS, there is disagreement on how and when to discontinue bracing. The purpose of this review was to investigate what criteria have been reported for initiating brace cessation and published weaning protocols and to look at estimates of the number of patients that may progress > 5 degrees after the end of growth.

METHODS

This scoping review summarizes existing knowledge on the best time to stop bracing in AIS patients, how to "wean," and what happens to spinal curves after bracing. Searches were carried out through MEDLINE, EMBASE, and PsycINFO in April 2022. A total of 1936 articles were reduced to 43 by 3 reviewers. Full papers were obtained, and data were extracted.

RESULTS

Weaning was most commonly determined by Risser 4 (girls) and 5 (boys). Other requirements included 2 years post-menarche and no growth in standing/sitting height for 6 months. Skeletal maturity assessed from hand and wrist radiographs, e.g., Sanders' stage; distal radius and ulnar physes, could determine the optimal weaning time to minimize curve progression. Complete discontinuation was the most common option at skeletal maturity; variations on weaning protocols involved gradual reduction of bracing over 6-12 months. Curve progression after weaning is common. The 12 studies reporting early curve progression after brace weaning found a mean Cobb angle progression of 3.8° (n = 1655). From the seven studies reporting early curve progression by > 5 degrees, there were 236/700 (34%) patients. There is limited information on risk factors to predict early curve progression after finishing brace treatment with larger curves, especially those over 40 degrees possibly having more chance of progression.

CONCLUSION

Curve progression after bracing cessation is a negative outcome for patients who have tolerated bracing for several years, especially if surgery is required. The literature shows that when to start brace cessation and weaning protocols vary. Approximately 34% of patients progressed by more than 5 degrees at 2-4 years after brace cessation or weaning. Larger curves seem more likely to progress. More research is needed to evaluate the risk factors for curve progression after brace treatment, defining the best time to stop bracing based on the lowest risk of curve progression and whether there is any benefit to weaning.

Reliability of the Risser+ grade for assessment of bone maturity in pediatric scoliosis cases: Investigation using standing and supine whole-spine radiograph

BACKGROUND

Although several radiography-based systems for assessing skeletal maturity are available to clinicians, the classical Risser grading system remains a clinical gold standard. For scoliosis follow-up, a standing whole-spine radiograph is usually used. However, in our clinical practice, we have occasionally encountered cases in which ossification of the iliac crest is seen differently in the standing and supine whole-spine radiography. Here, we aimed to clarify the reliability of the Risser+ grading system for supine versus standing position radiographs.

METHODS

This study recruited patients with all types of scoliosis who had been radiographed in both the standing and supine positions. We retrospectively evaluated the Risser+ grade of standing and supine whole-spine radiographs taken consecutively. Kappa statistics were computed to investigate the agreement between standing and supine Risser+ grades for this study.

RESULTS

We evaluated 111 patients (age: 12.6 ± 2.0; male-to-female = 23:88). The Kappa value for the standing and supine Risser+ grade systems was 0.74. The degree of agreement between the two positions for each Risser+ grade revealed high agreement for grades 0 and 5 in all cases, whereas grades 2 and 3 had low agreement.

CONCLUSIONS

Overall, there was substantial agreement between the Risser+ grades assigned to standing and supine position radiographs. However, disagreement was observed between standing and supine position radiographs assigned Risser+ grades of 2 or 3. Therefore, we have found a wide range in the visibility of iliac apophysis ossification of the iliac depending on the posture, and there are limitations in assessing bone maturity using the Risser+ grade alone. Clinicians should use other evaluation systems, in addition to the Risser+ system, to achieve a more accurate bone maturity assessment, especially for cases with standing position radiographs assigned Risser grades of 2 or 3.

A review on different methods of scoliosis brace fabrication

Adolescent idiopathic scoliosis is a 3D spinal deformity and mostly affects children in the age group of 10-16 years. Bracing is the most widely recommended nonoperative treatment modality for scoliosis in children. Scoliosis brace fabrication techniques have continuously evolved and currently use traditional plaster casting, computer-aided design (CAD) and computer-aided manufacturing (CAM), or 3D printing. This is a mini narrative literature review. The objective of our study is to conduct a narrative review of traditional, CAD-CAM and 3D printed brace manufacture. A narrative literature review of scoliosis brace manufacturing methods was conducted using PubMed, Cochrane, and other databases with appropriate keywords. Data were also collected from white papers of manufacturing companies. A total of 53 articles on scoliosis bracing manufacture were selected from various sources and subjected to detailed review. The shortlisted papers focused on Chêneau derivatives and Boston braces. Computer-aided design-CAM brace fabrication had similar curve correction compared with traditional plaster-cast braces; however, patient satisfaction may be greater in CAD-CAM braces. Traditional brace fabrication using plaster casting may be uncomfortable to patients. Computer-aided design-CAM and 3D printed braces may enhance comfort by augmenting the breathability and reducing brace weight. 3D printing is the most recently used brace fabrication method. 3D printing enables the manufacture of customized braces that can potentially enhance patient comfort and compliance and curve correction. 3D printing may also ease the bracing experience for patients and enhance the productivity of brace making.

Early Adherence to Prescribed Brace Wear for Adolescent Idiopathic Scoliosis Is Associated With Future Brace Wear

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To assess if initial adherence to prescribed brace wear for adolescent idiopathic scoliosis (AIS) predicts future adherence and curve improvement.

SUMMARY OF BACKGROUND DATA

AIS bracing can be effective if patients adhere to prescribed brace wear. Previous research has associated age, sex, and brace prescription length with future adherence. We hypothesize that a patient's initial adherence to brace wear may be associated with future adherence and outcomes.

MATERIALS AND METHODS

Consecutive AIS patients who met the Scoliosis Research Society (SRS) criteria for bracing from 2015 to 2019 at a single center were reviewed. Patients were stratified into groups based on their adherence during the initial one-month brace wean-in period-adherent patients were defined as wearing the brace >80% of the daily prescribed amount. Brace wear was recorded by a thermosensor and assessed during the wean-in period, six-, 12-, and 24-month postbracing appointments. Statistical testing was conducted to analyze if initial adherence was associated with future adherence, curve change, and bracing success -defined as reaching Risser stage 4 with a Cobb angle <40°.

RESULTS

Sixty patients (mean age=12.5 yr) were included, of which the majority were females (83%) with thoracic curves (70%). Thirty-two patients were considered adherent, and this cohort demonstrated improved adherence relative to the nonadherent group at the six-, 12-, and 24-month appointments ( P <0.001). Adherent patients also showed a significant reduction in their scoliosis at the 12-month appointment, unlike nonadherent patients ( P <0.001). Ninety-seven percent of adherent patients achieved bracing success compared with 71% of nonadherent ( P =0.016). Females were more likely to be adherent than males.

CONCLUSIONS

Initial adherence to prescribed AIS brace wear was associated with future adherence, bracing success, and curve improvement. Early recognition of nonadherence may offer an opportunity for supportive intervention to improve brace wear behavior.

Synthesis and Characterization of Carbon Nanotube-Doped Thermoplastic Nanocomposites for the Additive Manufacturing of Self-Sensing Piezoresistive Materials

We present carbon nanotube (CNT)-reinforced polypropylene random copolymer (PPR) nanocomposites for the additive manufacturing of self-sensing piezoresistive materials via fused filament fabrication. The PPR/CNT feedstock filaments were synthesized through high shear-induced melt blending with controlled CNT loading up to 8 wt % to enable three-dimensional (3D) printing of nanoengineered PPR/CNT composites. The CNTs were found to enhance crystallinity (up to 6%) in PPR-printed parts, contributing to the overall CNT-reinforcement effect that increases both stiffness and strength (increases of 56% in modulus and 40% in strength at 8 wt % CNT loading). Due to electrical conductivity (∼10^-4-10^-1 S/cm with CNT loading) imparted to the PPR by the CNT network, multifunctional in situ strain and damage sensing in 3D-printed CNT/PPR bulk composites and lattice structures are revealed. A useful range of gauge factors (k) is identified for strain sensing (k_s = 10.1-17.4) and damage sensing (k_d = 20-410) across the range of CNT loadings for the 0° print direction. Novel auxetic re-entrant and S-unit cell lattices are printed, with multifunctionality demonstrated as strain- and damage-sensing in tension. The PPR/CNT multifunctional nanocomposite lattices demonstrated here exhibit tunable strain and damage sensitivity and have application in biomedical engineering for the creation of self-sensing patient-specific devices such as orthopedic braces, where the ability to sense strain (and stress) can provide direct information for optimization of brace design/fit over the course of treatment.

Application of deep learning upon spinal radiographs to predict progression in adolescent idiopathic scoliosis at first clinic visit

BACKGROUND

Prediction of curve progression risk in adolescent idiopathic scoliosis (AIS) remains elusive. Prior studies have revealed the potential for three-dimensional (3D) morphological parameters to prognosticate progression, but these require specialized biplanar imaging equipment and labor-intensive software reconstruction. This study aimed to formulate a deep learning model with standing posteroanterior (PA) X-rays at first clinic visit to differentiate between progressive (P) and non-progressive (NP) curves.

METHODS

For this retrospective cohort study, we identified patients presenting with AIS between October 2015 to April 2020 at our tertiary referral centre. Patients with mild curvatures (11 - 30o) who were skeletally immature (Risser sign of ≤2) were recruited. Patients receiving biplanar X-ray radiographs (EOS™) were divided between a training-cross-validation cohort (328 patients) and independent testing cohort (110 patients). Another 52 patients receiving standard PA spinal X-rays were recruited for cross-platform validation. Following 3D reconstruction, we designated the major curve apex upon PA X-rays as the region of interest (ROI) for machine learning. A self-attentive capsule network was constructed to differentiate between curves manifesting P and NP trajectories. A two-stage transfer learning strategy was introduced to pre-train and fine-tune the model. Model performance (accuracy, sensitivity, specificity) was compared to that of traditional convolutional neural networks (CNNs) and a clinical parameter-based logistic regression model.

FINDINGS

3D reconstruction identified that apical rotation of the major curve and torsion were significantly different between P and NP curve trajectories. Our predictive model utilizing an ROI centered on the major curve apex achieved an accuracy of 76.6%, a sensitivity of 75.2% and a specificity of 80.2% upon independent testing. Cross-platform performance upon standard standing PA X-rays yielded an accuracy of 77.1%, a sensitivity of 73.5% and a specificity of 81.0%. Errors in prediction occurred when the degree of apical rotation / torsion was discrepant from that of the subsequent curve trajectory but could be rectified by considering serial X-rays. Performance was superior to that of traditional CNNs as well as clinical parameter-based regression models.

INTERPRETATION

This is the first report of automated prediction of AIS curve progression based on radiomics and deep learning, towards directing treatment strategy at first visit. Patients predicted to be at-risk of progression may be counselled to receive early bracing with enforcement of treatment compliance. Over-treatment may be avoided in curves deemed to be non-progressive. Results need to be consolidated in larger sample populations of different ethnicities.

FUNDING

The Society for the Relief of Disabled Children (SRDC).

Characterising the Mould Rectification Process for Designing Scoliosis Braces: Towards Automated Digital Design of 3D-Printed Braces

The plaster-casting method to create a scoliosis brace consists of mould generation and rectification to obtain the desired orthosis geometry. Alternative methods entail the use of 3D scanning and CAD/CAM. However, both manual and digital design entirely rely on the orthotist expertise. Characterisation of the rectification process is needed to ensure that digital designs are as efficient as plaster-cast designs. Three-dimensional scans of five patients, pre-, and post-rectification plaster moulds were obtained using a Structure Mark II scanner. Anatomical landmark positions, transverse section centroids, and 3D surface deviation analyses were performed to characterise the rectification process. The rectification process was characterised using two parameters. First, trends in the external contours of the rectified moulds were found, resulting in lateral tilt angles of 81 ± 3.8° and 83.3 ± 2.6° on the convex and concave side, respectively. Second, a rectification ratio at the iliac crest (0.23 ± 0.04 and 0.11 ± 0.02 on the convex and concave side, respectively) was devised, based on the pelvis width to estimate the volume to be removed. This study demonstrates that steps of the manual rectification process can be characterised. Results from this study can be fed into software to perform automatic digital rectification.

Is brace treatment unnecessary for cases of adolescent idiopathic scoliosis above Risser sign 3?

BACKGROUND

Skeletally mature cases of adolescent idiopathic scoliosis with mild curves are generally considered to have a low risk of deterioration. Previous reports have indicated that brace treatment in these cases has a high success rate; however, it is unclear whether brace treatment is necessary. The purpose of this study was to determine the incidence of adolescent idiopathic scoliosis progression during one year of follow-up in cases with a Risser sign ≥3, which were not treated with a brace, and to identify risk factors for progression.

METHODS

This retrospective, single center study included 54 cases of adolescent idiopathic scoliosis presenting to a university hospital in Japan between 2008 and 2017, with a Risser sign ≥3, which were not treated with brace treatment and had at least 2 years of follow-up data. The primary outcome was adolescent idiopathic scoliosis progression, defined as a deterioration in the Cobb angle of ≥ 6. Statistical analyses were performed to identify patient characteristics that were associated with progression.

RESULTS

The mean age of the 54 included cases was 14.1 years, and the male to female ratio was 8:46. Scoliosis progressed in 8 (14.8%) cases within 2 years of follow-up. Female patients with progression were more likely to have recently gone through menarche than those without progression (p < 0.01). There was a slight statistical difference in age (p < 0.05), but no significant differences in sex, Risser-sign Stage, initial Cobb angle or main curve between adolescent patients with and without progression.

CONCLUSIONS

We recommend brace treatment for cases of adolescent idiopathic scoliosis with a Risser sign ≥ 3 who have recently gone through menarche.

Non-invasive interventions in idiopathic scoliosis: a systematic review

Abstract Introduction: Idiopathic Scoliosis (IS) is an idiopathic curvature of the spine in all three plans, been treated conservatively (non-invasive) or surgicaly (invasive). The effectiveness of noninvasive therapy still remains lacking in a scientific basis to support their evidence-based applicability. Objective: Evaluate the effects of non-invasive interventions in spine lateral inclination in IS through a systematic literature review. Methods: The search of studies in MEDLINE, SCOPUS and COCHRANE databases was performed on 24th March, 2014. The terms used were: Scoliosis, therapeutic exercise, physical therapy. Clinical trials with scoliotic patients undergoing some type of non-invasive intervention were included. The outcome was spine lateral inclination. Results: The research found 941 studies, seven of these were included after a screening performed by two independent reviewers. Six studies (85.7%) have adopted some sort of kinesiotherapeutic technic, and three studies (42.8%) used corrective orthosis. The average intervention time in kinesiotherapeutic technique studies was of 37.6 weeks and 91.6 weeks in the studies of corrective brace. The progression improvement of the spine lateral inclination was reported by 83.3% (5 of 6) of the kinesiotherapeutic technique studies and in 66.6% (2 of 3) of studies with corrective brace. Conclusion: An improvement was found, in general, in the progression of spine lateral inclination in IS subjects of both sexes from 11 to 25 years of age undergoing non-invasive interventions.

To screen or not to screen for adolescent idiopathic scoliosis? A review of the literature

OBJECTIVES

Over the years, there has been much debate about the desirability and efficacy of screening for adolescent idiopathic scoliosis. To analyse the current evidence from a public health point of view a renewed evaluation of the literature was performed.

STUDY DESIGN

Literature review.

METHODS

We performed two literature searches: from January 2000 to April 2015 for systematic reviews or guidelines on screening for adolescent idiopathic scoliosis and from January 2009 to April 2015 for all studies on adolescent idiopathic scoliosis and screening methods. We evaluated if screening for adolescent idiopathic scoliosis fulfils the criteria of the UK National Screenings Committee for appraising a screening programme.

RESULTS

Adolescent idiopathic scoliosis is a condition with an unpredictable natural history. The optimal age and frequency of screening are unknown; it is not possible to predict which patients will need (conservative or surgical) treatment. The Forward Bending Test has a positive predictive value of 2.6% and a sensitivity of 56% (95% CI 23-88%) for (conservative or surgical) treatment, and is therefore not valid enough for use in a screening programme. There seems to be sufficient evidence that brace treatment is effective for preventing progression of adolescent idiopathic scoliosis. It is not clear if screening is cost effective.

CONCLUSIONS

Despite evidence that brace treatment is effective for preventing progression of adolescent idiopathic scoliosis, the benefits from the screening programme do not outweigh the harms. From a Public Health point of view, there is not enough evidence to support a screening programme for adolescent idiopathic scoliosis.

Anterior vertebral body tethering for idiopathic scoliosis: two-year results

STUDY DESIGN

Retrospective review.

OBJECTIVE

To report the 2-year results of the initial cohort undergoing anterior vertebral body tethering (VBT).

SUMMARY OF BACKGROUND DATA

Anterior VBT is a promising new technique with abundant preclinical studies but very few clinical results. It is a growth modulation technique, which utilizes patients' growth to attain progressive correction of their scoliosis. We report 2-year results of the initial cohort undergoing this procedure.

METHODS

After obtaining institutional review board approval, we retrospectively reviewed our first 11 consecutive patients who underwent anterior VBT with 2-year follow-up. We collected pertinent preoperative, intraoperative, and most recent clinical and radiographical data. Student t test and Fisher exact test were utilized to compare different time points.

RESULTS

Eleven patients with thoracic idiopathic scoliosis (8 females) were identified, with a mean age of 12.3 ± 1.6 years. Preoperatively, all were skeletally immature (Sanders mean = 3.4 ± 1.1; Risser mean = 0.6 ± 1.1). All underwent tethering of an average of 7.8 ± 0.9 (range: 7-9) levels, with the most proximal being T5 and the most distal L2. Preoperative thoracic Cobb angle averaged 44.2 ± 9.0° and corrected to 20.3 ± 11.0° on first erect, with progressive improvement at 2 years (Cobb angle = 13.5 ± 11.6°, % correction = 70%; P < 0.00002). Similarly, the preoperative lumbar curve of 25.1 ± 8.7° demonstrated progressive correction (first erect = 14.9 ± 4.9°, 2 yr = 7.2 ± 5.1°, % correction = 71%; P < 0.0002). Thoracic axial rotation as measured by a scoliometer went from 12.4 ± 3.3° preoperatively to 6.9 ± 3.4° at the most recent measurement (P < 0.01). No major complications were observed. As anticipated, 2 patients returned to the operating room at 2 years postoperatively for loosening of the tether to prevent overcorrection.

CONCLUSION

Anterior VBT is a promising technique for skeletally immature patients with idiopathic scoliosis. This technique can be performed safely and can result in progressive correction.

LEVEL OF EVIDENCE

4.