双螺栓与克氏针张力带固定治疗髌骨横形骨折模型的有限元分析

目的通过有限元分析法对比双螺栓固定系统与克氏针张力带固定系统固定髌骨横形骨折模型的稳定性。方法基于膝关节CT扫描数据,采用Mimics、Patran及Solidworks软件分别建立双螺栓与克氏针张力带固定髌骨横形骨折的有限元模型,采用Abaqus软件模拟屈膝90°髌股关节作用力600 N,分别对两个模型进行力学加载,分析位移及应力分布情况。结果螺栓系统固定治疗髌骨横形骨折时,螺栓与螺母相对最大位移为0.02396 mm,骨折端的最大接触应力值为47.57 Mpa,骨折端的最大等效应力57.40 MPa,螺栓的最大等效应力值为119.9 MPa;克氏针张力带固定治疗髌骨横形骨折时,克氏针相对最大位移为0.01338 mm,钢丝相对最大位移为0.00857 mm,骨折端的最大接触应力值为26.24 Mpa,骨折端的最大等效应力71.34 MPa,克氏针的最大等效应力值为63.1 MPa,钢丝的最大等效应力值为272.2 MPa。螺栓及克氏针张力带均存在应力集中现象,但最大应力值均小于屈服强度。结论双螺栓固定系统与克氏针张力带固定系统均能够用于髌骨横形骨折的治疗,螺栓固定的骨折端加压力更强,应力更为分散,克氏针张力带系统钢丝应力更为集中。

Finite element analysis of double bolt and K-wire tension band fixation in treating transverse patellar fracture

Objective The purpose of this study was to compare the stability of the double bolt fixation system and the K-wire tension band fixation system for the transverse patellar fracture model by finite element analysis. Methods Based on the CT data of the knee joint, finite element models of double bolt and K-wire tension band fixation of transverse patellar fracture were established respectively by Mimics, Patran and Solidworks software. 600N force was loaded on the patellofemoral joint when the knee joint was flexed in 90°position by Abaqus software respectively, displacement and stress distribution was recorded and analysed. Results In double bolt fixation system, the maximum relative displacement of bolt and nut was 0.02396 mm, the maximum contact stress of fracture was 47.57 Mpa, the maximum equivalent stress of fracture was 57.40 MPa and the maximum equivalent stress of bolt was 119.9 MPa. In K-wire tension band fixation system, the maximum relative displacement of Kirschner wire was 0.01338 mm, the maximum relative displacement of wire was 0.00857 mm, the maximum contact stress of fracture was 26.24 Mpa, the maximum equivalent stress of fracture was 71.34 MPa, the maximum equivalent stress of Kirschner wire was 63.1 MPa, the maximum equivalent stress of steel wire was 272.2 MPa. Stress concentration was existed between two systems, but the maximum stress values were less than the yield strength. Conclusion Both the double bolt fixation system and the K-wire tension band fixation system can be used for the treatment of transverse patellar fractures. The stress between the fractures is stronger and more dispersed in double-bolt fixation system. The stress of the K-wire tension band fixation system is more concentrated.