单双侧入路椎体后凸成形术治疗骨质疏松性椎体压缩骨折的生物力学研究

The Biomechanical Research of Unilateral and Bilateral Percutaneous Kyphoplasty for Treating Vertebral Compression Fracture of Osteoporosis

目的：比较单侧与双侧入路椎体后凸成形术对骨质疏松性椎体压缩骨折椎体力学性能的影响；方法：采用10例月龄为7～9月新鲜猪椎体标本（T13～L3），在每具标本随机选择3个椎体，制作成30个单椎体标本，随机平均分为3组，即正常对照组，双侧PKP组与单侧PKP组；按张智海等报道的方法将单侧与双侧组标本制成骨质疏松椎体模型；3组椎体经轴向加栽，记录骨折时的最大载荷及刚度数据，单侧与双侧组椎体压缩25％，制成椎体压缩骨折。单双侧组标本分别经单侧与双侧入路行椎体后凸成形术。然后将骨水泥强化治疗的椎体再次经万能力学试验机轴向加栽，记录治疗后最大载荷及刚度数据；结果：双侧PKP与单侧PKP两组椎体经过EDTA处理后最大栽荷与刚度均明显下降，较对照组相比差异有统计学意义（Pd0．05），且在x线下观察发现，骨密度较对照组椎体明显下降，骨质疏松标本制作是成功的。双侧与单侧PKP两组椎体骨折后经骨水泥强化，最大栽荷较自身脱钙后骨折前明显增加（P〈0．05），但单侧组仍小于双侧组（P〈0．05）。两组术后刚度较骨折前可有效恢复（P〉0．05），但单侧组与双侧组相比差异有统计学意义（P〈0．05），恢复不如双侧组；结论：经双侧入路PKP组可注入较多的骨水泥，椎体中骨水泥分布更均匀，椎体最大载荷与刚度恢复更佳，能取得更好的止痛效果并预防或避免己修复的椎体再次发生，骨折近期临床效果更佳。

Objective：To compare the biomechanical effects of unilateral and bilateral percutaneous kyphoplasty （PKP） for osteoporotic vertebral compression fractures. Methods：Ten fresh T13-L3 spine specimens of pigs, aged from 7 to 9 months were collected. In each sample, 3 vertebrae were randomly selected and made into 30 single vertebral specimens. All the veterbrae were randomly divided into 3 groups, namely normal control group, unilateral PKP group, and bilateral PKP group. According to the method of Zhang Zhihai＇s reports, the unilateral and bilateral groups of specimens were made into osteoporotic model. After exposure to axial loading, the maximum load and stiffness data were recorded when the fracture happened. Then they were made into vertebral compression fractures when the veterbrae in both unilateral and bilateral groups were compressed by 25%. Unilateral PKP group and bilateral PKP group were processed respectively by the unilateral and bilateral approach kyphoplasty. Then the bone cement augmentation treatment was given to both groups to test again the maximum loading and stiffness via universal mechanical testing machine. Results： After treatment with EDTA, maximum load and stiffness of unilateral and bilateral PKP group were decreased significantly. Compared with the control group, there was significant difference （P〈0.05）. Bone density of the veterbrae in both groups was significantly decreased, indicating successful model of osteoporosis. After reinforcement of the fractured vertebral bodies by bone cement, the maximum load was significantly increased in both groups compared with pre-fracture and after decalcification （P〈0.05）, but with less load in the unilateral group than the bilateral group （P〈0.05）. Postoperative stiffness of both groups were effectively restored （P〉0.05）, but there was statistical significance between the two groups （P〈0.05）. Conclusion： More bone cement can be injected in bilateral PKP group, and the bone cement can distribute more evenly. Better recovery of maximum load and stiffness occurs in bilateral PKP group, with better analgesic effect. Besides, bilateral PKP can prevent or avoid the occurrence of refraeture of the fractured vertebrae with good short-term clinical effect.