Lee John J, Rosenbaum Samuel L, Martusiewicz Alex, Holcombe Sven A, Wang Stewart C, Goulet James A
Department of Orthopaedic Surgery, University of Michigan, 1500 E Medical Center Dr, 2912 Taubmann Center, SPC 5328, Ann Arbor, 48109, Michigan.
J Orthop Res. 2015 Feb;33(2):277-82. doi: 10.1002/jor.22739. Epub 2014 Sep 17.
Variations in sacral segmentation may preclude safe placement of transsacral screws for posterior pelvis fixation. We developed a novel automated 3D technique to determine the safe zone size for transsacral screws in the upper two sacral segments in 526 adult pelvis computed tomography scans. Safe zone sizes were then compared by gender and sacral segmentation variations (number of neuroforamen and the presence/absence of lumbosacral transitional vertebrae, ± LSTV). Ten millimeters was used as the safety threshold for a large screw. 3 (0.6%), 366 (70%), and 157 (30%) sacra had 3, 4, or 5 neuroforamen, respectively. Eighty-eight (17%) were +LSTV. Safe zone size depended on gender, number of neuroforamen in -LSTV sacra and presence of LSTV (p < 0.001) but not on the uni- or bilateral nature of the LSTV. 17% of -LSTV sacra were below the safety threshold in S1, 27% in S2, whereas 3% of +LSTV sacra were below in S1, 74% in S2. Of -LSTV sacra that cannot take an S1 screw safely, 77% can do so in S2, leaving only 4% of sacra that cannot accommodate a screw safely in either upper segment. The results demonstrate a predictable pattern of safe zone size based on gender and sacral segmentation variations.
骶骨节段的变异可能会妨碍经骶骨螺钉在后骨盆固定中的安全置入。我们开发了一种新颖的自动化三维技术，用于在526例成人骨盆计算机断层扫描中确定上两个骶骨节段经骶骨螺钉的安全区大小。然后，根据性别和骶骨节段变异（神经孔数量以及腰骶部移行椎的有无，±LSTV）对安全区大小进行比较。将10毫米用作大螺钉的安全阈值。分别有3例（0.6%）、366例（70%）和157例（30%）骶骨有3个、4个或5个神经孔。88例（17%）为+LSTV。安全区大小取决于性别、-LSTV骶骨的神经孔数量以及LSTV的存在情况（p<0.001），但不取决于LSTV的单侧或双侧性质。-LSTV骶骨中，17%在S1低于安全阈值，27%在S2低于安全阈值；而+LSTV骶骨中，3%在S1低于安全阈值，74%在S2低于安全阈值。在不能安全置入S1螺钉的-LSTV骶骨中，77%在S2可以安全置入，只有4%的骶骨在两个上节段都不能安全容纳螺钉。结果表明，基于性别和骶骨节段变异，安全区大小呈现出可预测的模式。
