摘要目的 探讨单侧与双侧椎体后凸成形术(PKP)在恢复骨质疏松压缩性骨折椎体刚度中的差异，以及骨水泥分布对椎体两侧力学平衡的影响。方法 将27个胸椎椎体制作成压缩性骨折模型，随机分为3组（每组9个椎体）：经单侧椎弓根PKP 且骨水泥填充局限于椎体半侧组（A组）、经单侧椎弓根PKP 且骨水泥填充超过]线组（B组）及经双侧椎弓根PKP组（C组）。采用 MTS材料测试系统对所有椎体在3个不同时相中（完整状态、骨水泥强化前、骨水泥强化后）进行压缩试验。记录力和位移随时间变化的数据，比较椎体各时相、各部位的刚度值。结果 B组有1个椎体、C组有2个椎体被损坏，予以剔除，骨水泥强化前3组椎体标本的整体刚度较完整状态均显著下降，差异有统计学意义(P＜0.05)。骨水泥强化后,3组均可显著增加椎体的整体刚度，A组和B组刚度值[(251.37±23.34)、(250.41±21.27) N/m]与完整状态时的刚度水平[(260.48±34.15)、(257.60±31.44) N/m]比较差异无统计学意义(P＞0.05);而C组强化后的刚度值[(280.88±37.54) N/m]高于完整状态水平[(246.20±43.74) N/m](P ＜0.05)。骨水泥强化后，A组强化侧的刚度值可以恢复至完整状态水平,且显著高于非强化侧，差异有统计学意义(P＜0.05)。B组和C组椎体均可以均衡恢复两侧的刚度(P＞0.05)。结论 单侧与双侧PKP均可恢复压缩性骨折椎体的整体刚度。当骨水泥填充超过中线时，单侧PKP可以与双侧PKP一样使椎体两侧刚度得到均衡提高。

abstractsObjective To compare the effects of unipedicular and bipedicular percutaneous kyphoplasties (PKP) on stiffness of the compression-fractured vertebral bodies (VBs), and to assess the effect of cement distribution on bilateral biomechanical balance of the VBs following PKP. MethodsTwenty-seven VBs were made into models of compression-fracture and randomly assigned into 3 equal groups. Group A was treated with unipedicular PKP and cement augmentation limited to hemivertebral bodies, group B with unipedicular PKP and cement augmentation beyond the midline and onto the non-punctured side, and group C with bipedicular PKP. All the vertebrae and bilateral sides of the vertebrae were tested, on the MTS 858 bionix Ⅱ machine (USA), under continuous axial loads at intact, pre-augmentation and post-augmentation phases, respctively. The changes in force and displacement were rcorded to calculate the stiffness values of the whole vertebrae and their bilateral sides at different sites and phases.ResultsOne VB in group B and 2 VBs in group C were excluded due to damage. The stiffness values in groups A, B, and C were significantly decreased before augmentation compared to their intact state, and significantly increased after augmentation ( P ＜ 0. 05), but the stiffness value in groups A and B were comparable to their intact state ( P ＞0.05) while the stiffness value in group C was significantly higher then its intact state ( P ＜0. 05). In group A,stiffness of the augmented side was restored to its intact state after cement augmentation and significantly superior to that of the non-augmented side ( P ＜0. 05) . In groups B and C, the stiffness values at the bilateral sides were restored in balance ( P ＞ 0. 05).Conclusions Both unipedicular and bipedicular PKPs can restore the whole stiffness of the fractured VBs. In unipedicular PKP, when cement is augmented beyond the midline and adequately fills the other side, the stiffness at both sides can be as well restored in balance as in bipedicular PKP.