青少年特發性脊椎側彎(AIS)是最常見的脊椎側彎形式，通常會發生於大於十歲的兒童身上，脊椎側彎選擇使用背架治療是常見的治療方式，然而，背架(Brace)的生物力學機制和其治療策略尚未完全被釐清，因此，使用有限元素法來評估脊椎側彎穿搭背架的研究方法已被使用。但很可惜，過去文獻的數值模型較為簡化，為的是簡化其數值預測的限制。因此，本研究的目的是建構完整且擬真的人體脊椎側彎數值模型來模擬背架治療，並且探討與討論不同治療策略對於背架於脊椎側彎病患的影響。
本研究建立完整的三維脊椎側彎有限元素模型，利用此模型來了解不同治療策略的優勢和限制並考慮以下四組的治療策略，包含：第一群組：30mm-50mm-70mm-90mm水平位移、第二群組：90mm水平位移於沿著肋骨方向、第三群組：90mm水平位移加上50mm垂直位移、第四群組：90mm水平位移於連續兩個負載位置。為了驗證此脊椎側彎模型之可行性，將利用完整背架矯正模型之數值模擬與臨床X光影像進行比較，並計算Cobb angle、肩傾斜角、椎間盤應力、脊椎曲度與矯正誤差之數據並進行結果討論。
本研究利用已驗證之數值模型於背架治療獲得不錯的分析結果。在結果中發現，矯正效果透過肋骨將矯正能量從軀體傳遞至側彎脊椎上，其所預測的數值模型矯正結果接近於X光影像的表現，然而，胸椎椎間盤則顯示有高於腰椎椎間盤的應力。於第四群組位移負載中，其有最低的Cobb angle與矯正誤差，但有最高的肩傾斜角。在任意位移負載條件下，負載施加於脊椎側彎最凸位置均可獲得較好的Cobb angle矯正效果，但會增加椎間盤應力和肩傾斜角度，此外，本研究的結果能夠提供醫療人員了解背架治療於脊椎側彎的生物力學表現。

Adolescent idiopathic scoliosis (AIS) is the most common form of scoliosis. It typically affects children who are at least 10 years old. Wearing a brace is a choice for treating AIS. However, the biomechanical mechanism and treatment strategy of braces are not fully understood. Finite element method has been proposed for evaluating scoliotic spine with a brace. Unfortunately, simplifications in previous numerical models are performed, and such simplifications can limit the numerical prediction. Thus, the purpose of this study was to develop a realistic human scoliotic spine model with a bracing treatment. Additionally, different treatment strategies for bracing were also investigated and discussed.
Three-dimensional finite element models of the human scoliotic spine model were developed. To understand the strengths and limitations of different treatment strategies for bracing, four groups of the treatment strategies were considered including Group 1: horizontal displacement with 30mm-50mm-70mm-90mm, Group 2: along direction of rib with 90mm , Group 3: horizontal displacement in 90mm and vertical displacement in 50mm, and Group 4: horizontal displacement with 90mm in continuous two position. To validate the feasibility of the scoliotic spine model, the correction results predicted by the numerical models were compared with that of the X-ray image. In post-processing, the Cobb angle, shoulder tilted, disc stress, spinal curve, and correction error were calculated.
This study developed the validated numerical model to analyze the biomechanics of scoliotic spine with bracing. The result showed that the correction forces get through from trunk to spine via rib cage, and the correction outcome predicted by the numerical models was close to the X-ray image. The maximum stress of the thoracic discs revealed higher value than that of the lumbar discs. There were lowest Cobb angle and correction error in the Group 4, but they had highest shoulder tilted. A minimal Cobb angle can be achieved when a displacement is applied at the most convex segment of scoliotic spine. This study can help medical stuff to understand the biomechanics of scoliotic patients before and after a bracing treatment.

[1] K.-J. Cho, S.-I. Suk, S.-R. Park, J.-H. Kim, and J.-H. Jung, “Selection of proximal fusion level for adult degenerative lumbar scoliosis,” European Spine Journal, vol. 22, no. 2, pp. 394-401, 2013.
[2] B. B. Carlson, D. C. Burton, and M. A. Asher, “Comparison of trunk and spine deformity in adolescent idiopathic scoliosis,” Scoliosis, vol. 8, no. 1, pp. 2, 2013.
[3] S. Donzelli, S. Poma, L. Balzarini, A. Borboni, S. Respizzi, J. H. Villafane, F. Zaina, and S. Negrini, “State of the art of current 3-D scoliosis classifications: a systematic review from a clinical perspective,” Journal of Neuroengineering and Rehabilitation, vol. 12, no. 1, pp. 91, 2015.
[4] C. Vergari, I. Courtois, E. Ebermeyer, H. Bouloussa, R. Vialle, and W. Skalli, “Experimental validation of a patient-specific model of orthotic action in adolescent idiopathic scoliosis,” European Spine Journal, vol. 25, no. 10, pp. 3049-3055, 2016.
[5] N. Ramirez, P. Valentin, M. García-Cartagena, S. Samalot, and I. Iriarte, “One-step (standard) versus two-step surgical approach in adolescent idiopathic scoliosis posterior spinal fusion: Which is better?,” European Journal of Orthopaedic Surgery & Traumatology, vol. 26, no. 5, pp. 441-446, 2016.
[6] O. H. Mayer, “Scoliosis and the impact in neuromuscular disease,” Paediatric Respiratory Reviews, vol. 16, no. 1, pp. 35-42, 2015.
[7] C. Li, M. Yang, C. Wang, C. Wang, J. Fan, Z. Chen, X. Wei, G. Zhang, Y. Bai, and X. Zhu, “Preoperative factors predicting intraoperative blood loss in female patients with adolescent idiopathic scoliosis,” Medicine, vol. 94, no. 1, pp. 1-5, 2015.
[8] P. Hadagali, “Subject-specific finite element modeling of the adolescent thoracic spine for scoliosis research,” Drexel University, 2014.
[9] K. HAJIZADEH, “Developing a 3D multi-body simulation tool to study dynamic behaviour of human scoliosis,” 2013.
[10] S. C. Mordecai, and H. V. Dabke, “Efficacy of exercise therapy for the treatment of adolescent idiopathic scoliosis: a review of the literature,” European Spine Journal, vol. 21, no. 3, pp. 382-389, 2012.
[11] Z. Zhu, L. Xu, X. Sun, J. Qiao, B. Qian, S. Mao, and Y. Qiu, “Is brace treatment appropriate for adolescent idiopathic scoliosis patients refusing surgery with cobb angle between 40 and 50 degrees,” Clinical Spine Surgery, pp. 85-89, 2016.
[12] D. Périé, C. Aubin, Y. Petit, H. Labelle, and J. Dansereau, “Personalized biomechanical simulations of orthotic treatment in idiopathic scoliosis,” Clinical Biomechanics, vol. 19, no. 2, pp. 190-195, 2004.
[13] M. Driscoll, J.-M. Mac-Thiong, H. Labelle, S. Stad, H. Serhan, and S. Parent, “Biomechanical comparison of 2 different pedicle screw systems during the surgical correction of adult spinal deformities,” Spine Deformity, vol. 3, no. 2, pp. 114-121, 2015.
[14] P. C. Celestre, L. Y. Carreon, L. G. Lenke, D. J. Sucato, and S. D. Glassman, “Sagittal alignment two years after selective and nonselective thoracic fusion for Lenke 1C adolescent idiopathic scoliosis,” Spine Deformity, vol. 3, no. 6, pp. 560-565, 2015.
[15] M. Driscoll, C.-E. Aubin, A. Moreau, and S. Parent, “Biomechanical comparison of fusionless growth modulation corrective techniques in pediatric scoliosis,” Medical & Biological Engineering & Computing, vol. 49, no. 12, pp. 1437-1445, 2011.
[16] P. Trobisch, O. Suess, and F. Schwab, “Idiopathic scoliosis,” Dtsch Arztebl Int, vol. 107, no. 49, pp. 875-883, 2010.
[17] N. Cobetto, C. Aubin, S. Parent, J. Clin, S. Barchi, I. Turgeon, and H. Labelle, “Effectiveness of braces designed using computer-aided design and manufacturing (CAD/CAM) and finite element simulation compared to CAD/CAM only for the conservative treatment of adolescent idiopathic scoliosis: a prospective randomized controlled trial,” European Spine Journal, vol. 25, no. 10, pp. 3056-3064, 2016.
[18] F. Desbiens-Blais, J. Clin, S. Parent, H. Labelle, and C.-E. Aubin, “New brace design combining CAD/CAM and biomechanical simulation for the treatment of adolescent idiopathic scoliosis,” Clinical Biomechanics, vol. 27, no. 10, pp. 999-1005, 2012.
[19] A. Sattout, J. Clin, N. Cobetto, H. Labelle, and C.-E. Aubin, “Biomechanical assessment of providence nighttime brace for the treatment of adolescent idiopathic scoliosis,” Spine Deformity, vol. 4, no. 4, pp. 253-260, 2016.
[20] E. H. Lou, A. C. Chan, A. Donauer, M. Tilburn, and D. L. Hill, “Ultrasound-assisted brace casting for adolescent idiopathic scoliosis, IRSSD best research paper 2014,” Scoliosis, vol. 10, no. 1, pp. 13, 2015.
[21] G. T. Wynarsky, and A. B. Schultz, “Optimization of skeletal configuration: studies of scoliosis correction biomechanics,” Journal of Biomechanics, vol. 24, no. 8, pp. 721-732, 1991.
[22] D. Gignac, C.-É. Aubin, J. Dansereau, and H. Labelle, “Optimization method for 3D bracing correction of scoliosis using a finite element model,” European Spine Journal, vol. 9, no. 3, pp. 185-190, 2000.
[23] W. Nie, G. Fang, and Y. Yan, “Design of individual brace for the 3-D correction and mechanics study,” pp. 1362-1365, 2015.
[24] S. Pasha, C.-E. Aubin, H. Labelle, S. Parent, and J.-M. Mac-Thiong, “The biomechanical effects of spinal fusion on the sacral loading in adolescent idiopathic scoliosis,” Clinical Biomechanics, vol. 30, no. 9, pp. 981-987, 2015.
[25] F.-H. Cheng, S.-L. Shih, W.-K. Chou, C.-L. Liu, W.-H. Sung, and C.-S. Chen, “Finite element analysis of the scoliotic spine under different loading conditions,” Bio-medical Materials and Engineering, vol. 20, no. 5, pp. 251-259, 2010.
[26] D. Perie, C. Aubin, M. Lacroix, Y. Lafon, and H. Labelle, “Biomechanical modelling of orthotic treatment of the scoliotic spine including a detailed representation of the brace-torso interface,” pp. 339-344, 2004.
[27] N. Lalonde, I. Villemure, R. Pannetier, S. Parent, and C.-É. Aubin, “Biomechanical modeling of the lateral decubitus posture during corrective scoliosis surgery,” Clinical Biomechanics, vol. 25, no. 6, pp. 510-516, 2010.
[28] W. Wang, G. R. Baran, R. R. Betz, A. F. Samdani, J. M. Pahys, and P. J. Cahill, “The use of finite element models to assist understanding and treatment for scoliosis: a review paper,” Spine Deformity, vol. 2, no. 1, pp. 10-27, 2014.
[29] G. Wood, “Brace modifications that can result in improved curve correction in idiopathic scoliosis,” Scoliosis, vol. 9, no. 1, pp. 2, 2014.
[30] C. Vergari, G. Ribes, B. Aubert, C. Adam, L. Miladi, B. Ilharreborde, K. Abelin-Genevois, P. Rouch, and W. Skalli, “Evaluation of a patient-specific finite-element model to simulate conservative treatment in adolescent idiopathic scoliosis,” Spine Deformity, vol. 3, no. 1, pp. 4-11, 2015.
[31] M. Yagi, N. Hosogane, K. Watanabe, T. Asazuma, M. Matsumoto, and K. S. R. Group, “The paravertebral muscle and psoas for the maintenance of global spinal alignment in patient with degenerative lumbar scoliosis,” The Spine Journal, vol. 16, no. 4, pp. 451-458, 2016.
[32] D. Ignasiak, S. Dendorfer, and S. J. Ferguson, “Thoracolumbar spine model with articulated ribcage for the prediction of dynamic spinal loading,” Journal of Biomechanics, vol. 49, no. 6, pp. 959-966, 2016.
[33] A. Awoukeng Goumtcha, M. Bodo, L. Taddei, and S. Roth, “From military to civil loadings: Preliminary numerical‐based thorax injury criteria investigations,” International Journal for Numerical Methods In Biomedical Engineering, 2015.
[34] S. Langensiepen, O. Semler, R. Sobottke, O. Fricke, J. Franklin, E. Schönau, and P. Eysel, “Measuring procedures to determine the cobb angle in idiopathic scoliosis: a systematic review,” European Spine Journal, vol. 22, no. 11, pp. 2360-2371, 2013.
[35] X.-s. Qiu, W.-w. Ma, W.-g. Li, B. Wang, Y. Yu, Z.-z. Zhu, B.-p. Qian, F. Zhu, X. Sun, and B. K. Ng, “Discrepancy between radiographic shoulder balance and cosmetic shoulder balance in adolescent idiopathic scoliosis patients with double thoracic curve,” European Spine Journal, vol. 18, no. 1, pp. 45-51, 2009.
[36] F. Balagué, and F. Pellisé, “Adolescent idiopathic scoliosis and back pain,” Scoliosis and Spinal Disorders, vol. 11, no. 1, pp. 27, 2016.