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Background: Orthotic treatment is a well-acknowledged conservative treatment for moderate adolescent idiopathic scoliosis (AIS). The efficacy of this treatment is significantly determined by the forces applied to the bodies of patients. However, there is uncertainty regarding the optimal force levels that should be applied to the patient's torso by spinal orthosis. This study aims to identify reference values for the controlling forces in AIS management. Methods: A comprehensive literature search was performed in five databases (PubMed, Scopus, Cochrane Library, CINAHL, and Web of Science). Only studies written in English and covering the force/pressure measurements of spinal orthosis for the treatment of AIS were included, without publication date restrictions. The methodological index for non-randomized studies (MINORS) was employed for the methodological quality assessment, and force measurements were standardized to pressure in kilopascals (kPa) for comparison. Results: From the initial 10,452 records, 10 studies were admitted for the final analysis. All the included studies reported the interface pressure between the thoracic (T) pad and patient's trunk, and seven studies evaluated the pressure from the thoracolumbar/lumbar (TL/L) pad. These studies used different pressure sensors or transducers with the range from 5.6 to 82.5 kPa for the T pads, and 4.8 to 85.1 kPa for the TL/L pads. Four studies reported strap tensions of 26.8 to 60.4 N. Higher strap tension was correlated with increased interface pressure (r = 0.84). Conclusion: The mean strap tension was 42.5 N, the median interface pressure of the T pads was 8.75 kPa, and the median pressure of TL/L regions was 7.11 kPa without the outliers. The findings provide a baseline value for designing adjustable straps and strategically distributing pressure in orthoses. [ABSTRACT FROM AUTHOR]

Abstract Background Spinal orthoses are commonly prescribed for adolescent idiopathic scoliosis (AIS), yet their three-dimensional correction was not fully understood. The amount of deformity control largely depends on the corrective forces applied, which remain empirically based due to a lack of consensus on optimal force application. This study investigated the effects of different corrective force directions exerted by spinal orthoses on patients with AIS. Methods A retrospective analysis was conducted on 78 subjects. The trunk was segmented into four quadrants using coronal and sagittal planes from a top-down perspective. Each left or right posterolateral quadrant (with 90°) was further subdivided into zones 1–4, from the sagittal to coronal planes. Based on the zone where the resultant corrective force direction fell, the subjects were categorized into Group 1 (zone 1), Group 2 (zone 2), Group 3 (zone 3), or Group 4 (zone 4). The direction of the corrective force was estimated using modified models of the subjects’ bodies, designed through a computer-aided design and manufacturing system integral to the orthosis fabrication process. The effects of corrective forces in different zones on scoliotic spine were assessed. Results Among the subjects, 3 were in Group 1, 17 in Group 2, 52 in Group 3, and 6 in Group 4. Due to the limited number of subjects, data from Groups 1 and 4 were not analysed. Groups 2 and 3 showed significant reductions in Cobb angle in the coronal plane and plane of maximum curvature (PMC) following orthosis fitting (p 5º in thoracic kyphosis (p 0.05) but was notably higher in Group 2 after orthosis fitting (p

Introduction: The standard clinical practice and the biomechanical correction concepts of orthotic treatment for adolescent idiopathic scoliosis (AIS) have not been clearly defined. The purpose of this project was 1) to use a survey tool that polls expert opinions of experienced spinal orthotists to identify areas of agreement or disagreement regarding the current practice of orthotic treatment and the key biomechanical elements in treating AIS and 2) to share the literature review results of all topics identified with significant disagreement in the survey. Materials and Methods: Online-based survey and literature review methods were used. Twenty-one survey questions related to orthotic biomechanical concepts along with the posteroanterior view and lateral view x-rays of typical case examples were developed using multiple-choice style including three questions for defining qualification for data. The participant inclusion criteria were either a certified orthotist or a certified orthotist and prosthetist, who has at least 2 years of scoliosis orthotic treatment experience. A review of the literature was conducted on each of the areas identified as a topic of disagreement from the survey. Results: Fifty people were surveyed, and 46 people were qualified for inclusion. Participants agreed with 11 biomechanical orthotic correction topics. The majority of participants considered reducing Cobb angle in orthosis as well as aligning to the neutral alignment of the spine and trunk in all three planes as the important orthotic biomechanical goal in treating AIS. They selected the derotational force(s) as a primary correction force(s) for the thoracic curve and the lumbar curve. The placements of the lumbar corrective force for the lumbar curve and the sagittal corrective forces for the double major curves case were agreed between participants. They also reached a clear agreement for the questions regarding the orthotic design for the axillary area, orthotic recommendations for the C7 decompensation, and considerations for the usage of a trochanter extension. However, seven topics failed to find a clear agreement: the level of a thoracic pad for right thoracic curve case; the placement(s) of a primary corrective force(s) in the sagittal plane to address the thoracic hypokyphosis case; the necessity of abdominal compression for nonlumbar hyperlordosis case; the necessity of reducing lumbar lordosis for nonlumbar hyperlordosis case; orthotic recommendation for a single primary curve case (more than 35° Cobb angle), where the apex is located at or below T12/L1; orthotic recommendation for an upper thoracic curve (with an apex T2–T6)/cervicothoracic curve (with an apex C7–T1) case; and the treatment necessity for pelvic obliquity case, secondary to scoliosis. Conclusions: Experts agreed with 11 biomechanical orthotic correction topics. Some answers for seven topics, on which participants failed to reach an agreement, were found through the literature review. The area that had the most disagreement occurred on questions regarding treatment of the sagittal plane. The question regarding the placement of a thoracic pad for a single thoracic curve was not yet clear. More quantitative investigations are still needed to understand biomechanical correction concepts while treating AIS with an orthosis. [ABSTRACT FROM AUTHOR]

Abstract: Background: Adolescent idiopathic scoliosis is a complex spinal pathology characterized as a three-dimensional spine deformity combined with vertebral rotation. Various surgical techniques for correction of severe scoliotic deformity have evolved and became more advanced in applying the corrective forces. The objective of this study was to investigate the relationship between corrective forces acting on deformed rods and degree of scoliosis correction. Methods: Implant rod geometries of six adolescent idiopathic scoliosis patients were measured before and after surgery. An elasto-plastic finite element model of the implant rod before surgery was reconstructed for each patient. An inverse method based on Finite Element Analysis was used to apply forces to the implant rod model such that it was deformed the same after surgery. Relationship between the magnitude of corrective forces and degree of correction expressed as change of Cobb angle was evaluated. The effects of screw configuration on the corrective forces were also investigated. Findings: Corrective forces acting on rods and degree of correction were not correlated. Increase in number of implant screws tended to decrease the magnitude of corrective forces but did not provide higher degree of correction. Although greater correction was achieved with higher screw density, the forces increased at some level. Interpretation: The biomechanics of scoliosis correction is not only dependent to the corrective forces acting on implant rods but also associated with various parameters such as screw placement configuration and spine stiffness. Considering the magnitude of forces, increasing screw density is not guaranteed as the safest surgical strategy. [Copyright &y& Elsevier]