经骶1-2侧块螺钉固定的解剖学研究

目的:研究经骶1-2侧块螺钉固定的解剖学特征,探讨该技术的可行性。方法:对27例(男14例,女13例)骶尾椎CT资料进行三维重建,利用Advantage Workstation 4.2后处理工作站软件测量以第2骶后孔上缘上方5mm为进钉点的经骶1-2侧块螺钉(the sacral 1-2 translateral mass screw,STMS)固定的相关解剖学数据,包括:外倾角(从进钉点到骶骨翼最前上角的连线在水平面上与骶骨正中线的夹角)、上倾角(从进钉点到骶骨翼最前上角的连线与S1椎体上终板在矢状位上的夹角)及钉道长度(从进钉点到骶骨翼最前上角的距离)。对不同性别间及左右侧别间进行统计学分析。在三维图形上观察钉道轨迹,并根据上述测量数据在15例骶骨标本上置入STMS,观察螺钉与椎管、骶前后孔及耳状面关系。结果:平均外倾角男性为30.39°±5.01°,女性为35.81°±4.45°,男性左侧为31.14°±5.25°,右侧为29.64°±4.86°;女性左侧为36.46°±4.94°,右侧为35.15°±4.00°,性别间的差异有显著性意义(P<0.05),男性及女性的左右侧比较,差异无显著性意义(P>0.05)。平均上倾角男性为26.71°±16.50°,女性为19.48°±9.09°;左侧为23.67°±14.81°,右侧为22.22°±12.89°;平均钉道长度男性为54.48±3.01mm,女性为53.02±2.89mm;左侧为53.99±2.78mm,右侧为53.56±3.28mm。上倾角及钉道长度在性别及侧别间均无显著性差异(P>0.05)。在三维重建图形上观察钉道位于侧块内,置钉实验中STMS均未穿透至椎管、骶前后孔及耳状面。结论:在S1椎弓根螺钉不能提供有效固定的情况下,术前行CT三维测量以获得进钉参数,经骶1-2侧块螺钉固定技术可以安全的应用于骶骨固定。

Anatomic study of the posterior sacral 1-2 translateral mass screw fixation

Objectives:To investigate the anatomic characteristics and feasibility of the posterior sacral 1-2 translateral mass screw(STMS) fixation.Methods:Three-dimensional CT reconstructions of sacrums from 27 cases(14 males and 13 females) were obtained.The Advantage Workstation(AW) 4.2 software was used to process the anatomic data of STMS.The screw entry point located at 5mm above the superior edge of the second sacral foramen.The projection of the screw was determined as from the entry point to the top corner of the sacral ala.The parameters used for statistical analysis included the extraversion angle(the angle between the line from the entry point to the top corner of the sacral ala and the median line crossing sacrum at the horizontal plane),the inclined angle(the angle between the line from the entry point to the top corner of the sacral ala and the line parallel to the upper endplate of S1 vertebra at the sagittal plane) and the length(the distance from the entry point to the top corner of the sacral ala).The channel of STMS was observed on three-dimensional reconstruction.STMS placement was performed on 15 cadavers′ sacrums based on the above-mentioned parameters,then the relationships between STMS and the spinal canal,facet,the anterior and posterior sacral foramen were investigated.Results:There was significant difference as for the extraversion angle of STMS between males and females(P<0.05),the average extraversion angle of STMS was 30.39°±5.01° for males,31.14°±5.25° and 29.64°±4.86° for left and right side,while 35.81°±4.45° for females,36.46°±4.94° and 35.15°±4.00° for left and right side.No sex-related or side-related significant difference was noted as for extraversion angle(P>0.05) as well as inclined angle and the length of STMS.The average inclined angle of STMS was 26.71°±16.50° for males and 19.48°±9.09° for females,and 22.22°±12.89° for the right and 23.67°±14.81° for the left.The average length of STMS was 54.48±3.01mm for males and 53.02±2.89mm for females,and 53.56±3.28mm for right and 53.99±2.78mm for left.The channel of STMS located in the lateral mass on three-dimensional reconstruction completely with no penetration into the spinal canal,facet,and anterior or posterior sacral foramen.Conclusions:By obtaining the parameters of screw fixation for STMS in three-dimensional reconstruction of sacrum before having operation,the technique of STMS can be performed safely during the fixation of sacrum,especially when the S1 screw fixation can not be installed effectively.