Polikeit Anne, Nolte Lutz Peter, Ferguson Stephen J
ME Müller Institute for Biomechanics, University of Bern, Bern, Switzerland.
Spine (Phila Pa 1976). 2003 May 15;28(10):991-6. doi: 10.1097/01.BRS.0000061987.71624.17.
The effect of cement augmentation on an osteoporotic lumbar functional spinal unit was investigated using finite-element analysis.
To evaluate the influence of cement augmentation on load transfer, stresses, and strains.
Osteoporosis is the most frequent skeletal disease of the elderly, leading to weakness of the bony structures. Cement injection into vertebral bodies has been used to treat osteoporotic compression fractures of the spine. The clinical results are encouraging. Experimental biomechanical studies showed significant increases in stiffness and strength of treated bodies. However, little is known about the consequences for the adjacent, nontreated levels.
Three-dimensional finite-element models of L2-L3 were developed and the material properties adapted to simulate osteoporosis. The influence of augmentation level as well as uni- and bipedicular filling with polymethylmethacrylate were investigated. Compression, flexion, and lateral bending were simulated.
Augmentation increased the pressure in the nucleus pulposus and the deflection of the adjacent endplate. The stresses and strains in the vertebrae next to an augmentation were increased, and their distribution was changed. Larger areas were subjected to higher stresses and strains. The treatment clearly altered the load transfer. Changes to the overall stress and strain distribution were less pronounced for unipedicular augmentation.
Cement augmentation restores the strength of treated vertebrae, but leads to increased endplate bulge and an altered load transfer in adjacent vertebrae. This supports the hypothesis that rigid cement augmentation may facilitate the subsequent collapse of adjacent vertebrae. Further study is required to determine the optimal reinforcement material and filling volume to minimize this effect.
采用有限元分析研究骨水泥强化对骨质疏松性腰椎功能脊柱单元的影响。
评估骨水泥强化对载荷传递、应力和应变的影响。
骨质疏松症是老年人最常见的骨骼疾病，会导致骨结构变弱。向椎体注射骨水泥已被用于治疗脊柱骨质疏松性压缩骨折。临床结果令人鼓舞。实验生物力学研究表明，治疗后的椎体刚度和强度显著增加。然而，对于相邻未治疗节段的影响知之甚少。
建立L2-L3的三维有限元模型，并调整材料属性以模拟骨质疏松症。研究强化节段以及聚甲基丙烯酸甲酯单侧和双侧填充的影响。模拟压缩、屈曲和侧弯。
强化增加了髓核内压力和相邻终板的挠度。强化相邻椎体的应力和应变增加，并改变了其分布。更大的区域承受更高的应力和应变。该治疗明显改变了载荷传递。单侧强化对整体应力和应变分布的改变不太明显。
骨水泥强化可恢复治疗椎体的强度，但会导致相邻椎体终板膨出增加和载荷传递改变。这支持了刚性骨水泥强化可能会促进相邻椎体随后塌陷的假说。需要进一步研究以确定最佳的强化材料和填充量，以尽量减少这种影响。
