不同方法治疗不稳定骨盆骨折中前环损伤的有限元分析

目的:比较5种不同固定方法治疗不稳定骨盆骨折中前环损伤的生物力学稳定性,为临床治疗提供参考。方法:使用三维有限元方法,建立一侧骶髂关节脱位合并耻骨支骨折的不稳定骨盆骨折模型(Tile C型),模拟前方采用5种不同的固定方法,后方统一采用骶髂螺钉进行固定,并在模拟站立状态下比较分析不同组合固定方法治疗后的骨盆环的von Mises应力及应变分布情况。结果:竖直方向500 N载荷加载后,前方骨折处最大应力3.56 MPa(前方外固定架组),骶髂关节和骨折处总位移和Y轴上垂直位移在应力下均未超过1.5 mm。其中前方经皮入路组和前方外固定架组在内固定、骨折前方、骶髂关节处的最大应力明显大于改良Stoppa入路组、传统的髂腹股沟入路组、空心螺钉组,且在骶髂关节和骨折处的总位移和Y轴上垂直位移也大于其他3组。结论:不稳定性骨盆骨折中的前环损伤在5种组合方法植入物的固定后均能得到明显的改善,但采用改良Stoppa入路、髂腹股沟入路、前方空心钉固定方法治疗前环损伤在生物力学总体性能要优于前方经皮入路和前方外固定架治疗的方法。

Finite element analysis of anterior ring injuries in unstable pelvic fractures treated by different methods

Objective: To compare the biomechanical stability of different fixation methods for anterior ring injury of unstable pelvic fractures, and to provide reference for clinical treatment.Methods: An unstable pelvic fracture model (Tile C) with one side of the sacroiliac joint dislocation and the pubic rami fracture was constructed via three-dimensional finite element analysis. Five different fixation methods were used in the front, and the rear was fixed with sacroiliac screws. The von Mises stress and strain distributions of different combinations of fixation methods were analyzed under mimicking standing conditions.Results: After being loaded with 500 N vertically, the maximum stress in the anterior fracture was 3.56 MPa in anterior pelvic external fixation (AEF) group, the total displacement and the vertical displacement of the Y axis at the sacroiliac joint and the fracture were not more than 1.5 mm. The maximum stress at fixation, the front of the fracture and sacroiliac joints in the anterior pelvic subcutaneous approach (APA) group and AEF, was significantly higher than anterior modified Stoppa approach (ASA) group, anterior pelvic Ilioinguinal approach (AIA) group, and canulated screw fixation (CSF) group. The total displacement and the vertical displacement of the Y axis at the sacroiliac joint and the fracture in APA group and AEF group were also greater than the other three groups.Conclusion: Anterior ring injury of unstable pelvic fractures can be significantly improved after the fixation of the implants in the five combined methods. However, overall biomechanical properties of ASA, AIA and CSF group are superior to APA and AEF group.