Chon Chang-Soo, Jeong Jin-Hoon, Kang Bokku, Kim Han Sung, Jung Gu-Hee
Department of Biomedical Engineering, Yonsei University, Wonju, Gangwon-Do, 26493, Korea.
Department of Orthopaedic Surgery, College of Medicine and Gyeongsang National University Changwon Hospital, Gyeongsang National University, Samjunga-dong 555, Chang-won si, 642-160, Korea.
Eur J Orthop Surg Traumatol. 2018 Apr;28(3):439-444. doi: 10.1007/s00590-017-2061-2. Epub 2017 Oct 13.
Despite a high possibility of technique-related complications, ilio-sacral (IS) screw fixation is the mainstay of operative management in posterior pelvic ring injuries. We aimed to make IS screw trajectory with fully intraosseous path that was optimal and consistent, and confirm the possibility of transiliac-transsacral (TITS) screw fixation in Asian sacrum.
Eighty-two cadaveric sacra (42 males and 40 females) were enrolled and underwent continuous 1.0-mm slice computed tomography (CT) scans. CT images were imported into Mimics software to reconstruct three-dimensional model of the pelvis. To simulate IS screws, we inserted 7.0-mm-sized TITS cylinder for first (S) and second (S) sacral segment and 7.0-mm oblique cylinder for S. TITS cylinder could not be inserted into S of 14 models (sacral variation models) but could be inserted into the S of all models. The actual length of virtual IS screws was measured, and anatomic features of safe zone (SZ) including the area, horizontal distance (HD), and vertical distance (VD) were evaluated by the possibility of TITS screw fixation in the S.
When the oblique cylinder was directed toward the opposite upper corner of S at the level of the first foramen, there was no cortical violation regardless of sacral variation. The average length of TITS cylinder was 152.3 mm (range 127.9-178.2 mm) in S and 136.0 mm (range 97.8-164.1 mm) in S, and for oblique cylinder it was 99.2 mm (range 82.4-132.2 mm). The average VD, HD, and the area of SZ were 15.5 mm (range 8.7-24.4 mm), 18.3 mm (range 12.7-26.6 mm), and 221.1 mm (range 91.1-386.7 mm), respectively. The VD and SZ of sacral variation were significantly higher than those of normal (both p = 0.001).
Considering the high variability of the S, it is better to direct the IS screw trajectory toward the opposite upper corner of the S at the level of first sacral foramen. If a TITS screw is needed, the transverse fixation for the S could be performed alternatively due to its sufficient osseous site even in Asian sacrum.
尽管与技术相关的并发症可能性较高，但髂骶（IS）螺钉固定仍是骨盆后环损伤手术治疗的主要方法。我们旨在使IS螺钉轨迹具有完全位于骨内的最佳且一致的路径，并确认在亚洲人骶骨中行经髂-经骶（TITS）螺钉固定的可能性。
纳入82具尸体骶骨（42例男性和40例女性），并进行连续1.0毫米层厚的计算机断层扫描（CT）。将CT图像导入Mimics软件以重建骨盆的三维模型。为模拟IS螺钉，我们在第一骶骨节段（S1）和第二骶骨节段（S2）插入7.0毫米大小的TITS圆柱体，在S3插入7.0毫米倾斜圆柱体。在14个模型（骶骨变异模型）中无法将TITS圆柱体插入S1，但在所有模型的S2中均可插入。测量虚拟IS螺钉的实际长度，并通过在S2中TITS螺钉固定的可能性评估安全区（SZ）的解剖特征，包括面积、水平距离（HD）和垂直距离（VD）。
当倾斜圆柱体在第一骶孔水平指向S1的对角上方时，无论骶骨变异情况如何均无皮质侵犯。S1中TITS圆柱体的平均长度为152.3毫米（范围127.9 - 178.2毫米），S2中为136.0毫米（范围97.8 - 164.1毫米），倾斜圆柱体为99.2毫米（范围82.4 - 132.2毫米）。SZ的平均VD、HD和面积分别为15.5毫米（范围8.7 - 24.4毫米）、18.3毫米（范围12.7 - 26.6毫米）和221.1平方毫米（范围91.1 - 386.7平方毫米）。骶骨变异的VD和SZ显著高于正常情况（均p = 0.001）。
考虑到S1的高度变异性，最好将IS螺钉轨迹指向第一骶孔水平S1的对角上方。如果需要TITS螺钉，即使在亚洲人骶骨中，由于S2有足够的骨质部位，也可选择对S2进行横向固定。
