Correlation Between Immediate In-Brace Correction and Biomechanical Effectiveness of Brace Treatment in Adolescent Idiopathic Scoliosis
Correlation Between Immediate In-Brace Correction and Biomechanical Effectiveness of Brace Treatment in Adolescent Idiopathic Scoliosis
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DOI：
10.1097/brs.0b013e3181cb46f6
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发表时间：
2010-08-15
期刊：
影响因子：
3
通讯作者：
Parent, Stefan
中科院分区：
文献类型：
--
作者：
Clin, Julien;Aubin, Carl-Eric;Parent, Stefan
研究设计。使用有限元模型模拟多支具设计，并评估其生物力学效果。研究冠状曲线即刻支具矫正与作用于顶椎的弯矩之间的相关性。即刻支具矫正通常被认为是长期支具效果的基础，但其生物力学解释尚不清楚。3例患者的三维几何形状通过多角度X线片和表面地形技术获得。建立了考虑重力的躯干有限元模型和参数支具模型。测试了脊柱的两组力学性能(刚性和柔性)。模拟支具在患者身上的安装。使用包括14个设计因素的实验设计框架，为每个患者测试了1024个不同的虚拟支架。对于每个支具，计算冠状Cobb角的即刻支具矫正量和作用于顶椎的弯矩，并研究它们之间的相关性。冠状曲线即刻矫正与对顶椎弯矩的影响呈线性相关(平均R2=0.88)。消除弯矩所需的即时矫正量在19%至61%之间，平均为48%(柔性脊柱模型)和27%(僵硬脊柱模型)。在柔性脊柱模型中，支架对顶椎弯矩的校正作用更大。在Hueter-Volkmann原理的框架内，冠状即刻支具矫正与相应的根尖弯矩之间的相关性可解释为即刻支具矫正与长期治疗结果之间的相关性。根据脊柱僵硬和脊柱节段的不同，需要立即矫正多少弯曲力矩，在理论上抵消脊柱侧弯畸形的进展。这项研究证实了即刻支具矫正对预测治疗的长期结果的重要性，并为理解支具生物力学提供了见解。
Study Design. Multiple brace designs were simulated using a finite element model and their biomechanical effect was evaluated.Objective. To study correlations between immediate in-brace correction of coronal curves and bending moments acting on the apical vertebrae.Summary of Background Data. Immediate in-brace correction has often been deemed as fundamental to long-term brace effect but the biomechanical explanation is unclear.Methods. Three-dimensional geometry of 3 patients was acquired using multiview radiographs and surface topography techniques. A finite element model of the patients' trunk including gravitational forces and a parametric brace model were created. Two sets of mechanical properties of the spine (stiff and flexible) were tested. Installation of the brace on the patients was simulated. Using an experimental design framework including fourteen design factors, 1024 different virtual braces were tested for each patient. For each brace, immediate in-brace correction of the coronal Cobb angles and the bending moment acting on the apical vertebrae were computed and their correlation was studied.Results. Immediate correction of coronal curves and corresponding impact on the apical vertebrae bending moments were linearly correlated (mean R-2 = 0.88). The amount of immediate correction necessary to nullify the bending moment ranged between 19% and 61% with average 48% (flexible spine model) and 27% (stiff spine model). The braces corrected the apical vertebrae bending moment more in the flexible spine model. In the framework of the Hueter-Volkmann principle, the correlation between coronal immediate in-brace correction and corresponding apical bending moment can be interpreted as a correlation between immediate in-brace correction and long-term treatment outcome. The amount of immediate correction necessary to invert the bending moments, and in theory counteract the progression of the scoliotic deformity, depends on spine stiffness and spine segment.Conclusion. This study confirms the importance of immediate in-brace correction to predict long-term outcome of the treatment and provides insights in the understanding of brace biomechanics.