椎体成形改进装置对骨质疏松性椎体压缩骨折模型的生物力学分析

A biomechanical study on vertebroplasty using modified instruments

[目的]应用椎体成形改进装置,为骨质疏松性椎体压缩骨折模型施行椎体成形术,与传统的经单侧及双侧椎弓根注射的椎体成形术相比较,评估椎体成形改进装置的临床应用价值。[方法]选用成年猪胸腰段五联椎体60具,随机分为A、B、C、D组,每组15具,A、B、C组均制备成中央椎体OVCFs模型,其中A组应用椎体成形改进装置行椎体中央成形术(AVP),B组行经单侧椎弓根椎体成形术(UVP),C组行经双侧椎弓根椎体成形术(BVP),D组为无骨质疏松组。术后CT观察骨水泥位置分布。采用电子万能试验机进行压缩试验,比较各组骨折椎体在充分复位和定量骨水泥强化后脊柱单元的极限抗压强度、刚度,并比较各类型手术操作所需时间及X线暴露时间。[结果]A、B、C组骨水泥注射量组间无显著性差异;行椎体成形术后,A组和C组在脊柱单元极限抗压强度S2与刚度R2恢复方面优于B组,差异有统计学意义(P<0.05),与对照组D组比较无明显差别(P>0.05);A、C组骨水泥椎体中央分布率显著高于B组;A、B组的手术时间显著低于C组,X线暴露时间方面,A、B组低于C组。[结论]椎体成形改进装置实施的椎体成形术能够将骨水泥填充在强化椎的中央区,显著提高脊柱单元的生物力学稳定性,且在手术时间及X线暴露时间方面具有优势。

[Objective] To investigate the biomechanical characteristics of the vertebroplasty using modified instruments for osteoporotic vertebral compression fracture, in comparison to the traditional vertebroplasty by unilateral or bilateral pedicle injection methods. [Methods] Sixty fresh thoracolumbar segments of swine were randomly divided into 4 groups, with15 segments in each group. Osteoporosis and compression fracture model of the central vertebral segment was made in groups A, B, and C, while the group D was control group without osteoporosis. The advanced vertebroplasty（AVP） using the modified instruments was conducted in the group A, whereas traditional unilateral pedicle vertebroplasty（UVP） and the bilateral pedicle vertebroplasty（BVP） were performed in the group B and C respectively. Postoperatively,distribution of the cement was observed with CT examination. After the compression test by electronic universal testing machine, the ultimate compressive strength, stiffness of the spine unit of each group was calculated and compared among groups. Furthermore, the operation duration time and X-ray exposure time were also recorded. [Results] PMMA injection volume showed no significant difference among groups A, B and C. After percutaneous vertebroplasty, the recovery of ultimate compressive strength S2 and stiffness of R2 in groups A and C was much better than that in group B, with significant difference（P〈0.05）, but revealing no significant difference with group D（P〈0.05）. The central distribution rate of the cement in groups A and C was significantly higher than that of group B. The operation time and X-ray exposure time in groups A, B was significantly lower than that of group C.[Conclusion] The modified instruments can fill the cement into the central part of the strengthened vertebral boby,thereby enhance the biomechanical stability of the spine unit significantly. Meanwhilte, the operative time and X-ray exposure time is acceptable.