Pei Xuan, Huang Jincheng, Qian Shenglong, Zhou Wei, Ke Xi, Wang Guodong, Lei Jianyin, Liu Ximing
Department of Orthopedics, General Hospital of Central Theater Command of Chinese PLA, Wuhan Hubei, 430070, P. R. China.
School of Medicine, Wuhan University of Science and Technology, Wuhan Hubei, 430081, P. R. China.
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. 2023 Oct 15;37(10):1205-1213. doi: 10.7507/1002-1892.202306043.
To compare the biomechanical differences among the five internal fixation modes in treatment of Day type Ⅱ crescent fracture dislocation of pelvis (CFDP), and find an internal fixation mode which was the most consistent with mechanical principles.
Based on the pelvic CT data of a healthy adult male volunteer, a Day type Ⅱ CFDP finite element model was established by using Mimics 17.0, ANSYS 12.0-ICEM, Abaqus 2020, and SolidWorks 2012 softwares. After verifying the validity of the finite element model by comparing the anatomical parameters with the three-dimensional reconstruction model and the mechanical validity verification, the fracture and dislocated joint of models were fixed with S sacroiliac screw combined with 1 LC-Ⅱ screw (S +LC-Ⅱ group), S sacroiliac screw combined with 2 LC-Ⅱ screws (S +2LC-Ⅱ group), S sacroiliac screw combined with 2 posterior iliac screws (S +2PIS group), S and S sacroiliac screws combined with 1 LC-Ⅱ screw (S +S +LC-Ⅱ group), S -alar-iliac (S AI) screw combined with 1 LC-Ⅱ screw (S AI+LC-Ⅱ group), respectively. After each internal fixation model was loaded with a force of 600 N in the standing position, the maximum displacement of the crescent fracture fragments, the maximum stress of the internal fixation (the maximum stress of the screw at the ilium fracture and the maximum stress of the screw at the sacroiliac joint), sacroiliac joint displacement, and bone stress distribution around internal fixation were observed in 5 groups.
The finite element model in this study has been verified to be effective. After loading 600 N stress, there was a certain displacement of the crescent fracture of pelvis in each internal fixation model, among which the S +LC-Ⅱ group was the largest, the S +2LC-Ⅱ group and the S +2PIS group were the smallest. The maximum stress of the internal fixation mainly concentrated at the sacroiliac joint and the fracture line of crescent fracture. The maximum stress of the screw at the sacroiliac joint was the largest in the S +LC-Ⅱ group and the smallest in the S AI+LC-Ⅱ group. The maximum stress of the screw at the ilium fracture was the largest in the S +2PIS group and the smallest in the S +2LC-Ⅱ group. The displacement of the sacroiliac joint was the largest in the S +LC-Ⅱ group and the smallest in the S +S +LC-Ⅱ group. In each internal fixation model, the maximum stress around the sacroiliac screws concentrated on the contact surface between the screw and the cortical bone, the maximum stress around the screws at the iliac bone concentrated on the cancellous bone of the fracture line, and the maximum stress around the S AI screw concentrated on the cancellous bone on the iliac side. The maximum bone stress around the screws at the sacroiliac joint was the largest in the S +LC-Ⅱ group and the smallest in the S AI+LC-Ⅱ group. The maximum bone stress around the screws at the ilium was the largest in the S +2PIS group and the smallest in the S +LC-Ⅱ group.
For the treatment of Day type Ⅱ CFDP, it is recommended to choose S sacroiliac screw combined with 1 LC-Ⅱ screw for internal fixation, which can achieve a firm fixation effect without increasing the number of screws.
比较骨盆DayⅡ型新月形骨折脱位（CFDP）五种内固定方式的生物力学差异，寻找最符合力学原理的内固定方式。
基于一名健康成年男性志愿者的骨盆CT数据，运用Mimics 17.0、ANSYS 12.0-ICEM、Abaqus 2020和SolidWorks 2012软件建立DayⅡ型CFDP有限元模型。通过将解剖参数与三维重建模型对比及力学有效性验证，证实有限元模型有效后，分别采用骶髂螺钉（S）联合1枚LC-Ⅱ螺钉（S+LC-Ⅱ组）、S联合2枚LC-Ⅱ螺钉（S+2LC-Ⅱ组）、S联合2枚髂后螺钉（S+2PIS组）、S和S骶髂螺钉联合1枚LC-Ⅱ螺钉（S+S+LC-Ⅱ组）、S-翼状髂骨（S AI）螺钉联合1枚LC-Ⅱ螺钉（S AI+LC-Ⅱ组）对模型的骨折及脱位关节进行固定。对各内固定模型在站立位施加600 N力后，观察5组模型中新月形骨折块的最大位移、内固定的最大应力（髂骨骨折处螺钉的最大应力和骶髂关节处螺钉的最大应力）、骶髂关节位移以及内固定周围的骨应力分布情况。
本研究中的有限元模型经证实有效。施加600 N应力后，各内固定模型中骨盆新月形骨折均有一定位移，其中S+LC-Ⅱ组最大，S+2LC-Ⅱ组和S+2PIS组最小。内固定的最大应力主要集中在骶髂关节和新月形骨折的骨折线处。骶髂关节处螺钉的最大应力在S+LC-Ⅱ组最大，在S AI+LC-Ⅱ组最小。髂骨骨折处螺钉的最大应力在S+2PIS组最大，在S+2LC-Ⅱ组最小。骶髂关节位移在S+LC-Ⅱ组最大，在S+S+LC-Ⅱ组最小。在各内固定模型中，骶髂螺钉周围的最大应力集中在螺钉与皮质骨的接触面上，髂骨处螺钉周围的最大应力集中在骨折线的松质骨上，S AI螺钉周围的最大应力集中在髂骨侧的松质骨上。骶髂关节处螺钉周围的最大骨应力在S+LC-Ⅱ组最大，在S AI+LC-Ⅱ组最小。髂骨处螺钉周围的最大骨应力在S+2PIS组最大，在S+LC-Ⅱ组最小。
对于DayⅡ型CFDP的治疗，建议选择骶髂螺钉联合1枚LC-Ⅱ螺钉进行内固定，在不增加螺钉数量的情况下可获得牢固的固定效果。
