舟骨中央区在舟骨螺旋CT影像中的确立与舟骨螺钉居中位置的选择

Establishment of a "central zone" in the scaphoid bone by computer analysis of three-dimensional reconstructions of computed tomography imaging and selection of central location of the scaphoid screw

目的:通过对舟骨螺旋CT三维影像的空间形态作数据分析,在舟骨内找到一个区域,当舟骨骨折后固定骨折的螺钉的轴线位于此区域内时,此螺钉可以被认为在舟骨中是居中的,这个区域被称为舟骨的中央区。方法:收集20例正常舟骨的螺旋CT数据,利用计算机手术计划与模拟软件VxWork中的"回缩"功能,将舟骨的三维重建影像向内均匀回缩,直至腰部为原舟骨腰部大小的1/3,之后再向内均匀回缩1.5 mm后得到一个新的三维影像,即为舟骨的中央区,观察中央区的形状,测量中央区的宽度。结果:所有舟骨中央区的形态大致相似,中央区的整体形状不规则,可以分为远极、腰部、近极3部分,其中腰部十分狭窄,最大径约在0.8～1.2 mm之间。结合中央区的形状和大小,认为舟骨螺钉可以在近极、腰部或远极居中,但使螺钉在整个舟骨中完全居中是很困难的。结论:舟骨螺旋CT影像中央区的建立为讨论舟骨螺钉的位置在舟骨内是否居中提供了基础。

Objective：To establish an area by generating a surface model located a certain distance inside the scaphoid bone by computer analysis of three-dimensional reconstructions of computed tomography images,and define the central zone of the scaphoid.Methods： Twenty cases of three-dimensional computed tomography reconstructions of normal scaphoids in a computerized operation planning and simulation system（Vxwork software） were obtained.The scaphoid surface model was shrunk by using the function ＂erode＂ in the software until the waist portion became the one third size of the original waist portion of the scaphoid,and then another 1.5 mm shrinkage was made to get the central zone.Geometry and size of the central zone were evaluated and measured.Results： Geometry of all central zones was similar,as irregular as the scaphoid.The central zone could be divided into distal pole,waist portion and proximal pole.The narrowest part in the central zone was the waist portion,whose diameter ranged from 0.8-1.2 mm.Based on irregularity and size of the central zone,a screw axis could only be possibly contained completely either in the proximal,waist or distal central zone area,as it was very difficult to place the screw centrally in the whole scaphoid.Conclusion： The establishment of the central zone of the scaphoid three-dimensional computed tomography images could provide a baseline for discussion of central placement for scaphoid screw.