水平方向经皮第二骶椎骶髂关节螺钉固定治疗骶骨纵形骨折的评价

Evaluation of transverse percutaneous fixation with iliosacral screws via the second sacral vertebra for longitudinal sacral fractures

目的探讨经皮S2骶髂关节螺钉固定的安全钉道，将其应用于骶骨纵形骨折患者并评价其效果。方法选取50名健康成年志愿者，男30名，女20名；年龄18—56岁，平均34．6岁。行腹部连续螺旋CT扫描，将原始．dicom格式数据导入MimicsInnovationSuite15．0软件，三维表面重建骨盆，以．st1文件格式存储，导入Imageware12．0软件，对标准骶骨矢状位进行多层剖分，分析并确定S2骶髂关节固定的最优钉道。2014年1月至2015年2月共收治10例骶骨纵形骨折患者，男7例，女3例；年龄20～51岁，平均38．3岁；骨折按照Tile分型：B2型4例，C1型6例，均为DenisⅡ区骨折，合并耻骨骨折3例。手术前对移位明显者行胫骨结节牵引复位，通过CT数据计算最优通道，手术采用标准仰卧位，首先对移位的耻骨进行复位、固定。C型臂X线机获得骶骨侧位图像，定位经皮骶髂关节S2椎体水平螺钉通道，在皮肤上做标记，打入2．5mm克氏针，沿克氏针以6．0mm空心螺钉固定，术后通过CT扫描及三维重建验证其准确性。结果矢状位S2骶髂关节螺钉固定安全区投影呈不规则水滴形，平均投影面积男性[（213．9±52．4）mm2]大于女性[（171．6±49．6）mm2]，平均螺钉最大长度男性大于[（135．2±12．9）mm]女性[（121．1±10．1）mm]，平均螺钉最大直径男性[（10．2±0．9）mm]大于女性[（9．1±0．8）mm]，差异均有统计学意义（P〈0．05）。术后X线片及CT平扫断层图像显示所有患者螺钉位置及长度满意，平均长度为98．2mm，平均手术时间为25．6min。术后经12～24个月随访，所有患者均未发生神经、血管损伤、骶髂关节螺钉松动及断裂等并发症。结论通过骶骨侧位图像投影确定水平置钉钉道及安全区，为经皮S2骶髂关节螺钉固定治疗骶骨纵形骨折提供了一种简单、安全的手术方式。

Objective To explore the safe bone channels for transverse placement of sacroiliac screws via the second sacral vertebra in the fixation of longitudinal fracture of the sacrum by digital analysis and clinical observation. Methods Firstly, abdomen CT scanning was performed in 50 healthy adult volunteers. They were 30 males and 20 females, aged from 18 to 56 years （mean, 34. 6 years） . After their CT images were transformed by software Materialise Mimics Innovation Suite 15.0, three-dimensional （3D） models of the pelvis were generated, stored in stereolithography format, and transferred into software Image- ware 12.0. In the standard antero-posterior position, the sacrum was segmented and the points of 2D image coordinate geometric boundary were extracted to generate an optimal channel for transverse placement of sacroiliac screws via the second sacral vertebra. Secondly, we admitted 10 patients with longitudinal fracture of the sacrum. They were 7 men and 3 women, aged from 20 to 51 years （average, 38.3 years） . By Tile classification, 4 cases were type B2 and 6 type C1. All the fractures were Denis region Ⅱ ones. Pubic ramus fracture was complicated in 3 cases. After traction reduction of the tibial tubercle was conducted for patients with obvious displacement, the optimal channel was calculated on the basis of the CT data. On the lateral images of the sacrum acquired before operation by C-arm fluoroscopy, the optimal channel for transverse placement of sacroiliac screws via the second sacral vertebra was located. After the skin was marked, 2.5 mm Kirschner wire was drilled and the 6. 0 mm hollow screws were fixated along the Kirschner wire. Postoperative CT scanning images and 3D reconstructed models were analyzed to validate the accuracy of screw placement. Results The pro- jection of safety bone channel on the sagittal fluoroscopy of S2 vertebral body displayed an irregular water drop shape; the projection area in males （213.9±52.4 mm2） was significantly larger than that in the females （171.6 ±49. 6 mm2） （ P 〈 0. 05）. The average length of the channel in men （135.2 ± 12. 9 ram） was significantly longer than that in women （121.1± 10, 1 ram）; the average diameter of the screw in men （10.2 ± 0. 9 ram） was also significantly larger than that in women （9. 1 ±0. 8 ram） （ P 〈 0.05）. The postoperative X-ray and CT scanning images showed satisfactory positions and lengths of the screws. The screw lengths averaged 98.2 mm; the operation time averaged 25.6 min. No nerve or vascular injury, loosening or breakage of the sacroiliac screws occurred in the patients. Follow-ups for 12 to 24 months revealed no other complications. Conclusion The safety channel for transverse placement of sacroiliac screws via the second sacral ver- tebra can be determined using the lateral 3D reconstruction images of the sacrum in preoperative planning, which facilitates the percutaneous transverse fixation of longitudinal fracture of the sacrum.