经皮椎体增强术后生物力学有限元模型的建立及应用

摘要

Objective To establish the biomechanical finite element model of patients with spinal compression frac-tures induced by lumbar 2 osteoporosis before and after being treated with bone cement injection , and to observe and comr-pare the stress changes before and after treatment between the sick vertebra and adjacent vertebra .Methods One 70-year-old patient with spinal compression fractures induced by lumbar 2 osteoporosis treated with percutaneous vertebral augmen-tation was randomly selected in our hospital .Bilateral lumbar 2 pedicles were injected with small amount of bone cement . After 2 years of follow-up, the vertebra and adjacent vertebral body had no new fractures , and no local pain .Taking the lumbar CT data of patients before and after treatment as the reference , we established a three-dimensional biomechanical fi-nite element model, and simulated patients'lumbar rotation, flexion and lateral flexion.Then, the stress changes were ob-served and compared before and after treatment between the sick vertebra and adjacent vertebra .Results The three-di-mensional biomechanical finite element model was successfully established .It contained a total of 211 618 element genera-tion, including 20 914 four-node shell elements , 190 107 ten-node elements , and 597 bar units.After the bone cement in-jection, the extension, flexion and lateral bending stress of lumbar 2 vertebra increased (all P<0.05), the stress of verte-bral rotation had no difference as compared with before (P>0.05), and no significant difference was found in the stress of lumbar 1 and 3 vertebral extension, flexion, rotation and lateral flexion before and after treatment (P>0.05).Conclusion The biomechanical finite element model helps to determine the prognosis of patients with spinal compression fractures in -duced by lumbar osteoporosis treated with bone cement injection .%目的：建立腰2椎体骨质疏松致压缩骨折患者应用骨水泥注入治疗前后生物力学有限元模型，观察对比病椎与相邻椎体治疗前后应力的改变情况。方法随机选取本院1例70岁腰2椎体骨质疏松致压缩骨折经皮实施椎体成形术治疗患者，双侧腰2椎弓根予以少量骨水泥注入，2年后随访其病椎与相邻的椎体均未见新发骨折，并且局部无疼痛。参照治疗前后患者腰椎CT资料，建立三维生物力学有限元模型，并模拟患者腰椎旋转、屈伸及左右侧屈，观察对比病椎与相邻椎体治疗前后应力的改变情况。结果成功建立腰2椎体骨质疏松致压缩骨折予以少量骨水泥注入治疗前后的三维生物力学有限元模型。共计211618个单元生成，其中20914个4节点壳单元、190107个10节点体单元、597个杆单元。骨水泥注入后，腰2椎体的伸、屈及侧屈应力较前增加（ P均＜0．05），椎体旋转时应力治疗前后比较无统计学差异（P＞0．05）；腰1及腰3椎体伸、屈、旋转及侧屈时应力治疗前后无差异（P＞0．05）。结论生物力学有限元模型有助于腰椎骨质疏松致压缩骨折患者骨水泥治疗的预后判定。