Yao Gong, Shen Yi-Xin, Li Min, Cai Bing
Department of Orthopaedics, the Second Affiliated Hospital of Soochow University, Suzhou 215004, Jiangsu, China.
Zhongguo Gu Shang. 2021 Aug 25;34(8):732-7. doi: 10.12200/j.issn.1003-0034.2021.08.008.
To investigate the biomechanical effects of different bone cement diffusion patterns in the treatment of osteoporotic vertebral compression fractures.
One volunteer with L1 osteoporotic vertebral compression fracture was selected, male, aged 68 years old, heighed 172 cm, weighted 60 kg, and healthy before. CT scans were used from T-L, CT data was extracted with Mimics software, and Geomagic wrap and Solidworks were used to model, and the three-dimensional finite element model (T-L) of preoperative osteoporotic vertebral compression fractures in the thoracolumbar segment was established. Similarly, the situations of bone cement dispersion in vertebroplasty were simulated (the situations of bone cement dispersion had the three kinds, including the bone cement not contacts with upper and lower endplates, the bone cement only contacts with upper endplates, and the bone cement contacts with upper and lower endplates). According to different diffusion situations, five types of loads were applied to the model:upright, upright plus forward flexion, upright plus backward extension, upright plus left bending, upright plus right rotation. Meanwhile, the model was compared with the cementless lumbar spine model, and the deformation and stress distribution of each model under load were recorded and compared.
After the establishing the finite element model of osteoporotic vertebral compression fracture in the thoracolumbar segment, it was found that the deformation of three different bone cement distribution models above was not significantly different. In L cancellous bone, the Von Mises stress of the cementless lumbar spine group was significantly higher than that of the cemented group. Among the three groups of different bone cement injection situations, the Von Mises stress in the group of bone cement contacts with upper and lower endplates was the lowest, followed by the group of bone cement only contacts with upper endplates, and the highest Von Mises stress was the group that bone cement contacts neither the upper or lower endplates. In the comparison of bone cement stress, the Von Mises stress in the group of bone cement contacts with upper and lower endplates was significantly higher than the other two groups (upright 12.375 MPa, upright plus forward flexion 16.411 MPa, upright plus backward extension 16.801 MPa, upright plus left bending 13.425 MPa, upright plus right rotation 13.014 MPa), and the Von Mises stress in the group of bone cement does not contact with upper and lower endplates was the lowest.
The bone cement contact with both upper and lower endplates can effectively absorb and transfer the stress level brought by the load, reduce the stress level of cancellous bone, and reduce the possibility of refracture of the operative vertebral body.
探讨不同骨水泥弥散方式在骨质疏松性椎体压缩骨折治疗中的生物力学效应。
选取1例L1骨质疏松性椎体压缩骨折志愿者，男性，68岁，身高172 cm，体重60 kg，既往体健。采用T-L段CT扫描，利用Mimics软件提取CT数据，通过Geomagic wrap和Solidworks进行建模，建立胸腰段术前骨质疏松性椎体压缩骨折的三维有限元模型（T-L）。同样，模拟椎体成形术中骨水泥弥散情况（骨水泥弥散情况有3种，包括骨水泥不接触上下终板、骨水泥仅接触上终板、骨水泥接触上下终板）。根据不同弥散情况，对模型施加5种载荷：直立、直立+前屈、直立+后伸、直立+左侧弯、直立+右旋。同时，将该模型与无骨水泥腰椎模型进行比较，记录并比较各模型在载荷作用下的变形及应力分布。
建立胸腰段骨质疏松性椎体压缩骨折有限元模型后，发现上述3种不同骨水泥分布模型的变形无明显差异。在L松质骨中，无骨水泥腰椎组的Von Mises应力明显高于骨水泥强化组。在3组不同骨水泥注入情况中，骨水泥接触上下终板组的Von Mises应力最低，其次是骨水泥仅接触上终板组，Von Mises应力最高的是骨水泥既不接触上终板也不接触下终板组。在骨水泥应力比较中，骨水泥接触上下终板组Von Mises应力明显高于其他两组（直立12.375 MPa，直立+前屈16.411 MPa，直立+后伸16.801 MPa，直立+左侧弯13.425 MPa，直立+右旋13.014 MPa），骨水泥不接触上下终板组Von Mises应力最低。
骨水泥接触上下终板可有效吸收和传递载荷带来的应力水平，降低松质骨应力水平，减少手术椎体再骨折的可能性。
