骶骨椎弓根及侧块的应用解剖研究

Anatomic study of pedicle and lateral mass of sacrum and coccyx

目的:研究骶骨椎弓根及侧块的解剖学结构特点,为骶骨椎弓根和侧块螺钉内固定技术应用提供理论依据。方法:随机选择60例成人患者骶尾骨螺旋CT图像资料,应用三维重建技术确定骶骨椎弓根和侧块的进钉点,测量骶骨椎弓根和侧块的螺钉置入钉道长度和角度。选择15例成人尸体标本进行大体解剖,确定骶骨椎弓根和侧块的进钉点,并测量螺钉置入的钉道长度和角度。结果:S1～S5的椎弓根和侧块变化较大但左右对称,椎弓根进钉点位于横突中线与骶后孔中点连线交点,侧块进钉点位于横突中线与骶外侧嵴交点内侧,椎弓根钉的钉道角度外倾约20°,侧块螺钉轴线内倾约20°。椎弓根、侧块及第一二尾骨均可容纳4mm以下的螺钉。骶骨椎弓根(S2～S5)是由五面皮质骨围绕而成的"三棱柱"状结构,而侧块只有3面皮质骨围城,且皮质骨壁间距大,对螺钉的夹持力较弱。而侧块钉道长度在S1～S3髂骨翼内长度较大,约为35～45mm,而S4～S5的侧块钉道长度与椎弓根接近,约10～15mm,置钉实验发现椎弓根和侧块发生位置错误的概率无显著性差异(P>0.05)。结论:骶骨的椎弓根和侧块以及尾骨都可为骶尾骨骨折内固定和稳定性重建提供有效的固定解剖基础,椎弓根钉固定较侧块固定技术可能更方便、更牢固。

Objective：To study the anatomic structure of sacral mass and pedicle from S1 to S5 and coccyx and to provide evidence for instrumentation at sacral and lateral mass.Method：CT images of 60 cases were collected randomly.The three dimensional image reconstruction was taken to explore the screw anchoring point at sacral pedicle and lateral mass as well as measuring the orientation and length and width of the sacral pedicle and lateral mass screw trace.And 15 cadaver specimens were collected,and the counterparts related to the screw fixation were also determined.Result：The screw anchoring point at pedicle and lateral mass from S1 to S5 was sited symmetrically.The anchoring points for sacral pedicle screws located at the intersection of the line connecting adjacent posterior sacral foramina and median line of sacral transverse process.While the anchoring point for lateral mass screw was on the media side of intersection between median line of sacral transverse process and lateral sacral crest.The shape of the sacrum pedicle from S2 to S5 were ＂three prism＂ with 5 cortex wall,while,the lateral mass comprised of only 3 cortex walls.The width of sacral pedicle from S1 to S5 and from Co1 to Co2 was enough to hold the screws of less than 4.0mm diameter.The range of pedicle length from S1 to S5 was from 10mm to 45mm,with the maximum length at S1-S3 media wing of iliac crest （35-45mm）,and the angles of pedicle and lateral mass screws were about 20° .No significant difference was found with respect to misplacement of screw between pedicle screws and lateral mass screws （P0.05）.Conclusion：Both sacral pedicle and lateral mass can provide enough space for screw placement due to sacrum and coccyx fracture,and pedicle screw fixation is more reliable and easier to manage than lateral mass fixation.