透视S_(1)椎体后缘入口位对经皮骶髂螺钉置入的指导意义

S1 posterior edge inlet view for placement of percutaneous sacroiliac screws

目的证明S_(1)椎体后缘入口位的透视对经皮骶髂螺钉置入存在指导意义。方法①收集134例正常成人骨盆CT资料,导入Mimics Medical 21.0系统,测量分析骶椎的解剖学参数,寻找S_(1)椎体前、后缘解剖学参数差异。②利用测量数据建立数学模型。对5个成年人尸体骨盆标本徒手置钉,采用传统透视技术(位),模拟临床实践。置钉完成后透视S1椎体前、后缘入口位,观察二者成像差异,直视下检查螺钉是否穿出骶管。③回顾性分析2019年1月至2020年10月华中科技大学同济医学院附属同济医院骨科收治的11例骨盆后环骨折患者临床资料;均接受经皮骶髂螺钉固定术,传统透视技术徒手置钉,术中分别透视S_(1)前、后缘入口位以指导螺钉安全置入;行CT检查确定是否存在螺钉错位。结果①正常人CT测量:S_(1)前缘入口位角(20.71°±11.89°)显著小于S_(1)后缘入口位角(41.99°±11.67°),S_(1)上终板宽度[(32.22±3.41)mm]显著大于S_(1)下终板宽度[(20.10±3.28)mm],S1椎体前、后缘存在解剖学差异,差异有统计学意义(P<0.05)。②尸体实验:5个标本中的2个出现了S_(1)椎体前、后缘入口位显像差异,且螺钉穿出骶管。③临床组:所有患者闭合复位满意。共置入17枚螺钉,S_(1)置入12枚螺钉,S_(2)置入5枚螺钉;手术时间84~141 min,平均114.4 min;透视次数69~101次,平均89.6次;术中出血量110~463 mL,平均296.6 mL;术后CT未观察到螺钉错位。结论S_(1)椎体前、后缘入口位角存在差异,透视后缘入口位能清晰显示椎体后缘,从而提高置钉的安全性。

Objective To evaluate the significance of S1 posterior edge inlet view for placement of percutaneous sacroiliac screws.Methods 1.CT data of the pelvis were collected from 134 normal adults and introduced into Mimics Medical 21.0 system.Anatomical parameters of sacral vertebrae were measured and analyzed to observe the anatomical disparities between the anterior and posterior edges of S1 vertebral body.A mathematical model was established using the data acquired.2.Manual placement of sacroiliac screws was performed using a conventional S1 posterior edge inlet view on the pelvic specimens from 5 adult cadavers in simulation of actual surgical situations.After placement,the inlet views from both the S1 anterior and posterior edges were taken to observe the imaging differences and to check if the screws had pierced the sacral canal.3.A retrospective study was conducted of the 11 patients with posterior pelvic ring fracture who had been treated at Department of Orthopaedics,Tongji Hospital from January 2019 to October 2020.Their fractures were fixated by percutaneous sacroiliac screws under the guidance of a C-arm X-ray machine.The manual placement of the screws was guided intraoperatively by the inlet views from both the S1 anterior and posterior edges to secure a safe placement.Pelvic CT examinations were performed to check any screw dislocation.Results 1.CT measurements in the normal adults showed that the angle of S1 anterior edge inlet view(20.71°±11.89°)was smaller than that of S1 posterior edge inlet view(41.99°±11.67°)and the width of S1 upper end plate[(32.22±3.41)mm]greater than that of S1 lower end plate[(20.10±3.28)mm],showing significant disparities in anatomy between the anterior and posterior edges of S1 vertebral body(P<0.05).2.In 2 of the 5 cadaveric specimens,imaging differences were observed between the inlet views of the anterior and posterior edges of S1 and the screws pierced out of the sacral canal.3.Satisfactory closed reduction was achieved in all the 11 patients.A total of 17 screws were placed,with 12 ones into S1 and 5 ones into S2.Operation time ranged from 84 to 141 min(average,114.4 min),fluoroscopy frequency from 69 to 101 times(average,89.6 times),and intraoperative blood loss from 110 to 463 mL(average,296.6 mL).No screw dislocation was observed on postoperative CT.Conclusion As there is a difference between the inlet views of the anterior and posterior edges of S1 vertebral body,the inlet view of the posterior edge of S1 can display the posterior edge of S1 more clearly so as to improve the safety of placement of percutaneous sacroiliac screws.