水平方向骶髂关节螺钉固定治疗骶骨纵形骨折的安全性评价

目的探讨水平方向骶髂关节螺钉固定治疗骶骨纵形骨折的安全性。 方法收集2009年9月至12月期间100例不伴骨性疾病的骨盆CT容积性数据，男52例，女48例；平均年龄43.1岁（15 ～91岁）。重建三维模型，获得标准骶骨矢状面。在各个矢状层面标记骨皮质的外缘，从而确定手术的安全区，水平方向模拟置入1枚安全区所能容纳的最大螺钉，记录其直径。根据螺钉固定方式不同，分为单侧固定和贯穿固定。结果根据骶骨形态学评价标准，形态正常80例，变异20例，变异率为20.0％。单侧固定时螺钉直径：变异组S2(14.92±2.57) mm]＞正常组S2(12.37±1.84)rm] (P=0. 000)＞正常组S1(11.87±3.92) mm] (P=0.319)＞变异组S3(9.30±2.00) mm](P=0.000)。贯穿固定时螺钉直径：变异组S2(13.63±2.68) mm]＞正常组S2(11.48±1.92) mm](P=0.002)＞正常组S1(10.40±4.05) mm](P=0.033)＞变异组S3(7.95±2.26)mm](P=0.001)。正常组S2所能容纳螺钉最大直径与S1呈弱负相关，而各骶椎所能容纳螺钉最大直径与髋臼直径无相关。男性S2椎体所能容纳螺钉的平均直径大于女性，差异有统计学意义(P＜0.05)，S1椎体在性别间差异无统计学意义（P＞ 0.05）。结论绝大多数中国人可以在骨盆后环以水平方向固定2枚直径为6.5 mm的骶髂关节螺钉，但安全区较小。螺钉的入点、规格及所固定椎体S1椎体和（或）S2椎体]必须严格按照影像学表现进行选择。骶骨变异并不是骶髂关节螺钉固定术的禁忌证。

The safety of transverse iliosacral screw fixation of longitudinal sacral fracture

ObjectiveTo evaluate the safety of transverse iliosacral screw fixation of longitudinal sacral fracture.MethodsWe obtained CT scan data of the pelvis from 100 adults without any bony problems from September to December 2009. They were 52 males and 48 females, aged from 15 to 91 years (average, 43. 1 years) . We then reconstructed virtual three-dimensional models of the pelvis. The three-dimensional models were re-segmented through the sacral horizontal axis to obtain standard sagittal planes of the sacrum. To identify the safe zone for transverse screw fixation, we marked off the sacral margin on each sagittal plane. In simulation of the transverse screw ipsilateral fixation and transfixation, one single virtual cylindrical implant was inserted into the safe zone. The maximum diameter of the virtual cylindrical implant was measured.ResultsA 20. 0％ rate of sacral variation was observed (80 normal versus 20 deformed morphological sacrums). In ipsilateral fixation, the average screw diameter of variant S2 (14. 92 ± 2.57 mm) ＞normal S2 ( 12. 37 ± 1.84 mm) ( P =0. 000) ＞ normal S1 ( 11.87 ± 3.92 mm) ( P =0. 319 ) ＞ variant S3 (9. 30 ± 2. 00 mm) ( P =0. 000). In transfixation, the average screw diameter of variant S2 ( 13.63 ± 2. 68 mm) ＞ normalS2 (11.48 ±1.92mm) (P=0. 002) ＞ normal S1(10. 40 ±4.05 mm) (P=0.033) ＞variant S3 (7.95 ± 2. 26 mm) ( P =0. 001 ) . The maximum screw diameter of normal S2 showed a slightly negative correlation with that of normal S1, but there was no correlation between the maximum screw diameter for each sacral vertebra and the acetabulum diameter. The normal male S2 was significantly larger than the female one ( P ＜ 0.05), but there was no significant difference in S1 between genders ( P ＞ 0.05) .ConclusionsIn most Chinese people, the posterior pelvic ring could be fixed with 2 iliosacral screws of 6. 5 mm in diameter simultaneously in horizontal direction, but care should be taken because the safety zone is quite limited. A variant sacrum is not a contraindication for iliosacral screw fixation, but the entry point, the screw length and the sacral vertebra to be fixed must be determined after careful radiological evaluation.