中文摘要：

目的验证PUMCⅡd2型AIS手术治疗最佳融合节段。方法利用PUMCⅡd2型AIS有限元模型（T5-S），分别模拟上胸弯融合、下腰弯融合和双弯融合方式，在侧弯凹侧端椎椎弓根内分别赋予50N、100N、150N载荷，分别比较上弯端椎T5和下弯端椎T11在矢状面向上的位移（Z轴正值为矢状面向上的位移，负值为矢状面向下的位移）以及二者之间的差值，以T5位移代表双弯矫形效果，以T11位移代表下腰弯矫形效果，二者差值（T5-T11）代表上胸弯矫形效果。结果对于PUMCⅡd2型侧弯。T5在Z轴位移：双弯矫型较单纯上弯或者下弯矫形融合大（F=8，P〈0．05）。3种载荷对于T5-T11位移差：双弯矫形〉单纯上胸弯矫形〉单纯下腰弯矫形（F=8，P〈0．05）。3种载荷对于T11在z轴位移：双弯矫形〉单纯下腰弯矫形〉单纯上胸弯矫形（F=8，P〈0．05）。结论对于PUMCⅡd2型侧弯，双弯矫型内固定较单纯上弯或者下弯矫形融合内固定效果好。对于上胸弯的矫正效果，双弯矫形大于单纯上胸弯矫形，最次为单纯下腰弯矫形；对于下腰弯的矫正效果，双弯矫形大于单纯下腰弯矫形，最次为单纯上胸弯矫形。三维有限元分析法可以作为一种很有效的方法应用于脊柱侧弯畸形矫正生物力学分析，为临床开创了一种虚拟的、无创的验证方式，优化手术方案。

英文摘要：

Objective To explore the best surgical fusion level for adolescent idiopathic scoliosis （AIS） of PUMC Ⅱd2 with finite element model （FEM）. Methods FEM （ T5-S） of PUMC Ⅱd2 idiopathic seoliosis was used to simulate upper thoracic curve, lower lumbar curve and double curve fusion manners. The pedicle of concave vertebral arch received 50, 100 and 150 N load respectively. Displacement of T5 and T11 on upper sagittal plane （displacement of Z axis positive value on upper sagittal plane, displacement of negative value on lower sagittal plane ） and their different values were compared. T5 displacement represented the outcomes of double curve orthopedics. T11 displacement represented the outcomes of lower lumbar curve orthopedics. Their difference （ T5-T11 ） represented the outcomes of upper thoracic curve orthopedics. Different fusion segments and displacement of T5 and T11 under different orthopedic forces were measured. Results In PUMCⅡd2 lateral curvature, T5 displacement on Z axis： fusion displacement of double curve was greater than the upper or lower curve alone （ F = 8, P 〈 0. 01 ）. Difference of T5-T11 displacement： double curve orthopedics 〉 upper thoracic curve orthopedics alone 〉 lower lumbar curve orthopedics alone （F = 8, P 〈 0. 01 ）. Displacement of T11 on Z axis： double curve orthopedics 〉 lower lumbar curve orthopedics alone 〉 upper thoracic curve orthopedics alone （F = 8, P 〈 0. 01 ）. Conclusion Fusing two curves achieves the best effect on the AIS of PUMC Ⅱd2 in comparison with upper or lower curve fusion alone. Effects of 3 kinds of load on correction of upper thoracic curve ： double curve orthopedics 〉 upper thoracic curve orthopedics alone 〉 lower lumbar curve orthopedics alone. Effect of 3 kinds of load on correction of lower lumbar curve orthopedics alone： double curve orthopedics 〉 lower lumbar curve orthopedics alone 〉 upper thoracic curve orthopedics alone. Three-dimensional finite element analysis is an effective method to