To investigate the effects of postoperative fusion implantation on the mesoscopic biomechanical properties of vertebrae and bone tissue osteogenesis in idiopathic scoliosis, a macroscopic finite element model of the postoperative fusion device was developed, and a mesoscopic model of the bone unit was developed using the Saint Venant sub-model approach. To simulate human physiological conditions, the differences in biomechanical properties between macroscopic cortical bone and mesoscopic bone units under the same boundary conditions were studied, and the effects of fusion implantation on bone tissue growth at the mesoscopic scale were analyzed. The results showed that the stresses in the mesoscopic structure of the lumbar spine increased compared to the macroscopic structure, and the mesoscopic stress in this case is 2.606 to 5.958 times of the macroscopic stress; the stresses in the upper bone unit of the fusion device were greater than those in the lower part; the average stresses in the upper vertebral body end surfaces were ranked in the order of right, left, posterior and anterior; the stresses in the lower vertebral body were ranked in the order of left, posterior, right and anterior; and rotation was the condition with the greatest stress value in the bone unit. It is hypothesized that bone tissue osteogenesis is better on the upper face of the fusion than on the lower face, and that bone tissue growth rate on the upper face is in the order of right, left, posterior, and anterior; while on the lower face, it is in the order of left, posterior, right, and anterior; and that patients’ constant rotational movements after surgery is conducive to bone growth. The results of the study may provide a theoretical basis for the design of surgical protocols and optimization of fusion devices for idiopathic scoliosis.

为了探究特发性脊柱侧凸术后融合器的植入对椎骨细观生物力学性能与骨组织成骨性的影响，本文建立了术后植入融合器的宏观尺度有限元模型，利用圣维南原理子模型方法建立骨单元细观尺度模型。基于上述模型，本文模拟了人体生理工况，对比相同边界条件下宏观皮质骨与细观骨单元生物力学性能差异，分析细观尺度下融合器的植入对骨组织生长的影响。结果显示，腰椎细观结构的应力较宏观有所增加，此病例中细观应力为宏观应力的2.606～5.958倍，融合器上部骨单元应力较下部大；上部椎体端面平均应力按大小排序分别为右侧、左侧、后部、前部；下部椎体应力排序为左侧、后部、右侧、前部；旋转为骨单元应力值最大工况。据此推测，融合器上端面骨组织成骨性较下端面好，上端面骨组织生长快慢顺序为右侧、左侧、后部、前部；下端面为左侧、后部、右侧、前部；患者术后常做旋转运动，有利于骨骼生长。通过上述结果，期望本文研究可为特发性脊柱侧凸手术方案的设计与融合器优化提供理论依据。.