摘要
目的:应用MicroCT研究在不同骨密度(BMD)情况下椎弓根钉道骨小梁及钉道外口皮质骨空间结构与椎弓根螺钉轴向拔出力的关系。方法:对40个绵羊腰椎标本应用微量注射泵椎体内外盐酸脱钙方法分别建立4组不同BMD水平的生物力学模型,即A组(正常骨质),B组(骨量减少),C组(骨质疏松),D组(严重骨质疏松),生物力学测试各组椎体椎弓根螺钉的最大轴向拔出力(Fmax)。应用MicroCT研究各组椎体椎弓根钉道周围骨小梁参数,包括骨小梁厚度(Tb.th)、骨小梁数量(Tb.N)、骨小梁间隙(Tb.sp)、骨体积分数(BV/TV)及钉道外口皮质骨的厚度(Cor.th),统计分析其与椎弓根螺钉轴向拔出力的关系。结果:成功建立不同BMD下降程度的生物力学模型,B、C、D组BMD下降分别为19%、28%及37%。生物力学测试示B、C、D组椎体的Fmax较A组显著下降,且有统计学意义(P<0.05);B、C、D组组间椎体Fmax随BMD下降而下降,各组间具有统计学差异(P<0.05)。MicroCT显示各组椎弓根螺钉钉道空间结构参数随BMD下降而变化,且各组组间参数随脱钙时间的延长而变化,各组间有统计学意义(P<0.05)。相关性分析发现钉道骨质空间结构参数(Tb.th、Tb.N、Tb.sp、BV/TV、Cor.th)、BMD、脱钙时间与Fmax均存在直线相关关系;多元回归方程(y=1185.658×BMD+153.535×Tb.N-247.037×Tb.sp)可预测椎体椎弓根螺钉的Fmax。结论:椎弓根螺钉的最大轴向拔出力(Fmax)不仅与椎体BMD的变化密切相关,亦与椎弓根钉道松质骨及皮质骨空间结构参数密切相关。
Objective：To investigate trabecular and cortical bone structure and biomechanics around pedicle screw in lumbar vertebrae of sheep with different levels of bone mineral density（BMD）.Method：The biomechanical model of lumbar vertebrae with different levels of BMD was established by the method of decalcification with infusion pump and divided into four groups,which included group A（normal bone mass）,group B（osteopenia）,group C（osteoporosis） and group D（severe osteoporosis）.Axial pull-out strength test was performed on each group.The trabecular bone and cortical bone around the pedicle screw were harvested for microCT scanning to observe their microstructure parameters（Tb.th,Tb.N,Tb.sp,BV/TV,Cor.th）,and to analyze the relationship between them and the maximum axial pull-out force of pedicel screw（Fmax）.Result：Biomechanical models with different levels of BMD,including osteopenia（BMD decreased 18%）,osteoporosis（BMD decreased 28%） and severe osteoporosis（BMD decreased 35%） were established successfully.Biomechanics results showed the maximum force（Fmax） in group B,C and D was significantly lower than that in group A（P 0.05） and Fmax in group B,C and D was continuously decreasing with the decrease of BMD（P〈0.05）.MicroCT showed with decline in bone mineral density,parameters including Tb.th,Tb.N,BV/BF and Cor.th in group B,C and D were significantly lower,while Tb.sp was higher（P〈0.05 for both） compared with group A.Correlation analysis showed that there existed a linear correlation among microstructure parameters（Tb.th,Tb.N,Tb.sp,BV/TV,Cor.th）,BMD,decalcification time and Fmax.Multiple linear regression equation was as follower：y=1185.658×BMD＋153.535×Tb.N-247.037×Tb.sp,which could be used to evaluate Fmax.Conclusion：The maximum pull-out force of pedicle screw is not only closely related to the BMD in lumbar vertebrae,but also closely related to microstructure parameters（Tb.th,Tb.N,Tb.sp,BV/BF,Cor.th） in trabecular bone and cortical bone around pedicle screw.
出处
《中国脊柱脊髓杂志》
CAS
CSCD
北大核心
2010年第4期281-285,共5页
Chinese Journal of Spine and Spinal Cord
基金
国家863基金(2007AA02Z468)
关键词
最大轴向拔出力
骨密度
显微CT
体外脱矿化椎体模型
骨质疏松
Maximum force
Bone mineral density
MicroCT
In vitro demineralized vertebra model
Osteoporosis
Sheep
