经皮骶髂关节螺钉固定变异骶骨的影像学初步研究

Percutaneous sacroiliac screw fixation of dysplastic sacra： a primary image study

摘要:

目的：探讨变异第一骶椎（the first sacral vertebra，S1）骶髂螺钉的安全置钉范围和适应证。方法：连续收集我院267例成人骨盆CT数据，利用Mimics16.0软件三维重建骨盆及其周围皮肤，筛选变异S1椎，置入虚拟横行贯穿双侧骶髂关节螺钉，若不能安全置入者，则置入常规单侧骶髂螺钉，测量其安全置钉范围，确定体表进针点P1，髂前上棘及髂嵴体表定位点N1、M1，并测量各点间距离。结果：267例标本中30.3%的S1椎为“主要变异”（不能横置S1贯穿骶髂螺钉）。中心螺钉体表进钉点与定位点间距离P1N1：（162.52±21.23） mm（男），（163.52±20.39） mm（女）（P=0.761）；P1M1：（129.29±17.38） mm（男），（111.56±17.84） mm（女）（P=0.000）；M1N1：（146.92±11.08） mm（男），（146.72±15.05） mm（女）（P=0.924）。螺钉前倾角：（21.80±3.56）°（男），（19.97±3.02） °（女）（P=0.000）；头倾角：（29.97±5.38）°（男），（28.15±6.21） °（女）（P=0.047）。螺钉在骶骨Denis Ⅲ区内长度：（14.41±4.40） mm（男）、（14.09±5.04） mm（女）（P=0.665），在Ⅱ、Ⅲ区内长度和：（36.25±3.40） mm（男）、（38.04±4.60） mm（女）（P=0.005）。结论：无论男女，当S1椎为主要变异时，S1骶髂螺钉进钉点较正常骶骨进钉点偏后、偏尾侧，螺钉方向前倾20°，头倾30 °左右，适合固定骶骨DenisⅠ区骨折及骶髂关节脱位。

Abstract:

Objective：To Investigate the safety zone and indications of placing the upper sacral sacroiliac screw into the dysplastic sacra based on CT data. Methods：Totally 267 three-dimensional models of pelvis were reconstructed by Mimics（Materialize’s inter－active medical image control system） 16.0 software based on CT data and then the dysplastic sacra were detected. The virtual trans－verse screw which pass through the bilateral sacroiliac joint was planned to place into the dysplastic sacra，if not safe to be placed，the conventional unilateral sacroiliac screw was placed，and then the safety zone was measured. The skin around pelvic surface was recon－structed，and then the surface projections of the upper sacral central screw’s entry point P，anterior superior iliac spine’s vertex N，iliac crest point M were determined as P1，N1 and M1，respectively. The lengths of P1N1，P1M1 and M1N1 were measured in section. Results：Among 267 specimens，30.3 percent of sacra belonged to main dysplasia（upper sacral transverse sacroiliac screw could not be placed） and 9.0 percent of sacra belonged to minor dysplasia（upper sacral transverse sacroiliac screw could be placed）. For the main dysplastic sacra，the length of P1N1 was （162.52±21.23） mm in male and （163.52±20.39） mm in female（P=0.761）. The length of P1M1 was（129.29±17.38） mm in male and （111.56±17.84） mm in female（P=0.000）. The length of M1N1 was （146.92±11.08） mm in male and （146.72±15.05） mm in female（P=0.924）. The angle of the central screw oriented from posterior to anterior was （21.80±3.56）° in male and （19.97±3.02）° in female（P=0.000）. The angle oriented from caudal to cranial was （29.97±5.38）° in male and （28.15±6.21）° in female（P=0.047）. The length of the central screw in the Denis Ⅲ zone was （14.41±4.40） mm in male and （14.09±5.04） mm in female（P=0.665）；the length in the Denis Ⅱ and Ⅲ zones was （36.25±3.40） mm in male and （38.04±4.60） mm in female（P=0.005）. Conclusion：When the upper sacra have the feature of ‘the sacrum is not recessed within the pelvis’ and/or ‘the alar slope is acute’，the entry point of the upper sacral sacroiliac screw is more backward and caudal than the normal pelvic，and the angle oriented from posterior to ante－rior is about 20°，from caudal to cranial is about 30°. For the dysplastic sacra，the upper sacral sacroiliac screw is recommended to fix Denis Ⅰ zone sacral fracture and the sacroiliac dislocation. And there is no significant difference between man and women.