摘要
目的评价重度骨质疏松条件下椎弓根螺钉的稳定性,为椎弓根内固定在合并有重度骨质疏松症的患者中的选用提供力学理论基础。方法采用新鲜尸体脊柱标本,检测骨密度后,根据诊断标准,选用正常骨质的2具尸体标本、重度骨质疏松的4具尸体标本,分离T12-L5节段成单个椎体以备后用;然后在骨质正常椎体置入椎弓根螺钉12枚作对照组;在重度骨质疏松水平,分单纯置入椎弓根螺钉（pedicle screw,PS）、经磷酸钙骨水泥（calcium phosphate cement,CPC）强化钉道后置入椎弓根螺钉、经聚甲基丙烯酸甲酯（polymethylmethacrylate,PMMA）强化钉道后置入椎弓根螺钉三种方法置钉,依次为PS组、CPC/PS组和PMMA/PS组,进行螺钉轴向拔出实验,测最大拔出力、刚度和能量吸收值,对所测指标进行组间对比分析。结果重度疏松条件下,PS组、CPC/PS组和PMMA/PS各组最大拔出力、刚度、能量吸收值均显著低于对照组（P〈0.005）;但是,PMMA/PS组三项指标均显著高于PS组、CPC/PS组（P〈0.001）;PS组、CPC/PS组之间比较仅最大拔出力存在显著性差异（P〈0.05）,刚度与能量吸收值差异无统计学意义（P〉0.05）。结论重度骨质疏松条件下,椎弓根螺钉固定强度明显下降,不宜单纯应用普通椎弓根螺钉行脊柱内固定治疗,采用普通骨水泥强化钉道后置钉可以提高椎弓根螺钉稳定性。
Objective To evaluate the fixation of pedicle screw in the lumbar spine with severe osteoporosis,further to provide theoretical evidence for clinical application of pedicle screw in patient with severe osteoporosis. Methods Fresh human cadaver spines were used. Two of them were normal and four were severe osteoporosis,according to the value of bone mineral density. The vertebra was bilaterally instrumented pedicle screws,resulting in 24 screws in normal BMD group,as the control group. The vertebrae at severe osteoporosis level was bilaterally instrumented with pedicle screws according to three protocols,including pedicle screw without augmentation,pedicle screw with calcium phosphate cement（ CPC） augmentation,pedicle screw with poly（ methyl methacrylate）（ PMMA） augmentation,as group PS,group CPC / PS and group PMMA / PS,respectively.Sixteen pedicles per protocol were obtained in each group. Screw pullout tests were conducted. On the load-stroke curve,the maximum pullout strength,stiffness and energy absorption were determined. The differences between groups were compared.Results With the BMD decreasing in severe osteoporosis level,the maximum pullout strength,the stiffness and the absorbed energy of pedicle screw were correspondingly significantly lower than those of the control group（ P〈0. 005）. Also,the above three indexes of PMMA / PS group were significantly higher than those of PS and CPC / PS group（ P〈0. 001）,but no significance difference was found between PS and CPC / PS group in these indexes（ P〉0. 05） except but the pullout strength（ P〈0.05）. Conclusion Under the condition of severe osteoporosis,the purchase strength of pedicle screw decreases significantly,it should not be used alone in the spine surgery of internal fixation. After being augmented with PMMA,the stability of pedicle screw can be improved.
出处
《实用骨科杂志》
2015年第6期512-515,共4页
Journal of Practical Orthopaedics
基金
国家高技术研究发展计划(863计划)骨质疏松条件下提高脊柱内固定强度的整体解决方案(2007AA02Z468)
