Patient outcomes in idiopathic scoliosis are associated with biological endophenotypes: 2020 SOSORT award winner.

PURPOSE: Bracing is the treatment of choice for idiopathic scoliosis (IS), unfortunately factors underlying brace response remain unknown. Clinicians are currently unable to identify patients who may benefit from bracing, and therefore, better molecular stratification is critically needed. The aim of this study is to evaluate IS patient outcomes at skeletal maturity in relation to biological endophenotypes, and determine specific endophenotypes associated to differential bracing outcomes. This is a retrospective cohort with secondary cross-sectional comparative studies. METHODS: Clinical and radiological data were collected from 563 IS patients, stratified into biological endophenotypes (FG1, FG2, FG3) based on a cell-based test. Measured outcomes were maximum Cobb angle at skeletal maturity, and if severe, spinal deformity (≥ 45°) or surgery was attained. Treatment success/failure was determined by standard progression thresholds (Cobb ≥ 45° or surgery; Cobb angle progression ≥ 6°). Multivariable analyses were performed to evaluate associations between endophenotypes and clinical outcome. RESULTS: Higher Cobb angles at maturity for FG1 and FG2 patients were observed (p = 0.056 and p = 0.05), with increased likelihood of ≥ 45° and/or surgery for FG1 (OR = 2.181 [1.002-4.749] and FG2 (OR = 2.141 [1.038-4.413]) compared to FG3. FG3 was 9.31 [2.58-33.61] and 5.63 [2.11-15.05] times more likely for bracing success at treatment termination and based on the < 6° progression criterion, respectively, compared to FG1. CONCLUSION: Associations between biological endophenotypes and outcomes suggest differences in progression and/or bracing response among IS patients. Outcomes were most favorable in FG3 patients. The results pave the way for establishing personalized treatments, distinguishing who may benefit or not from treatment.

Braces Optimized With Computer-Assisted Design and Simulations Are Lighter, More Comfortable, and More Efficient Than Plaster-Cast Braces for the Treatment of Adolescent Idiopathic Scoliosis.

STUDY DESIGN: Feasibility study to compare the effectiveness of 2 brace design and fabrication methods for treatment of adolescent idiopathic scoliosis: a standard plaster-cast method and a computational method combining computer-aided design and fabrication and finite element simulation. OBJECTIVES: To improve brace design using a new brace design method. SUMMARY OF BACKGROUND DATA: Initial in-brace correction and patient's compliance to treatment are important factors for brace efficiency. Negative cosmetic appearance and functional discomfort resulting from pressure points, humidity, and restriction of movement can cause poor compliance with the prescribed wearing schedule. METHODS: A total of 15 consecutive patients with brace prescription were recruited. Two braces were designed and fabricated for each patient: a standard thoracolumbo-sacral orthosis brace fabricated using plaster-cast method and an improved brace for comfort (NewBrace) fabricated using a computational method combining computer-aided design and fabrication software (Rodin4D) and a simulation platform. Three-dimensional reconstructions of the torso and the trunk skeleton were used to create a personalized finite element model, which was used for brace design and predict correction. Simulated pressures on the torso and distance between the brace and patient's skin were used to remove ineffective brace material situated at more than 6 mm from the patient's skin. Biplanar radiographs of the patient wearing each brace were taken to compare their effectiveness. Patients filled out a questionnaire to compare their comfort. RESULTS: NewBraces were 61% thinner and had 32% less material than standard braces with equivalent correction. NewBraces were more comfortable (11 of 15 patients) or equivalent to (4 of 15 cases) standard braces. Simulated correction was simulated within 5° compared with in-brace results. CONCLUSIONS: This study demonstrates the feasibility of designing lighter and more comfortable braces with correction equivalent to standard braces. This design platform has the potential to further improve brace correction efficiency and its compliance.

New brace design combining CAD/CAM and biomechanical simulation for the treatment of adolescent idiopathic scoliosis.

BACKGROUND: A numerical based brace design platform, including biomechanical simulation, Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) was developed to rationalize braces for the treatment of adolescent idiopathic scoliosis. The objective of this study was to test the feasibility of the approach and assess the effectiveness of braces issued from this platform as compared to standard brace design. METHODS: The biomechanical finite element model was built using the 3D reconstruction of the trunk skeleton from bi-planar radiographs and of the torso surface from surface topography. The finite element model is linked to a CAD/CAM software (Rodin4D), allowing the iterative design and simulation of the correction provided by the brace, as well as predicting pressures exerted on the torso. The resulting brace design was then fabricated using a numerical controlled carver. A brace designed using this platform (New Brace) as well as a standard thoraco-lumbo-sacral orthosis (Standard Brace) were built for six scoliotic patients. Both brace effectiveness was assessed using radiographs and compared to the simulations. FINDINGS: The New Brace corrected on average the spine deformities within 5° of Cobb angle of the simulated correction and with a similar correction as compared to the Standard Brace (average correction of 16° vs. 11° (MT); P=0.1 and 13° vs. 16° (TL/L); P=0.5 for the Standard Brace and the New Brace respectively). The two braces had a similar 10° lordosing effect of the thoracic curve. The coronal balance was quite similar (7.3 vs. 6.8mm balance improvement respectively for New Brace vs. Standard Brace). INTERPRETATION: These first clinical results showed the feasibility of building computer-assisted braces, equivalent to standard orthosis. An extended study on more cases is under way to fully assess this new design paradigm, which in the long term would allow improving brace design and rationalize the conservative treatments of scoliosis.