Finite element analysis of distal femoral locking plate and minimally invasive internal fixation system in different motion states / 中国组织工程研究

ABSTRACT

BACKGROUND:Traditional distal femoral fixation plate screw breakage is relatively common. Designing good anatomical and attached fixation system is the key for clinical application. OBJECTIVE:To perform finite element analysis in two states of motion of the minimal y invasive distal femoral fixation system, compare stress distribution of different parts in the same fixed way, different fixed methods and the same fixed parts of different motion states. METHODS:Imaging data of a 34-year-old male patient weighing 68 kg with 33-C1 type fracture of distal femur were selected. CT data were input into Mimics 16.0 for reconstruction. PRO-E software was used to establish minimal y invasive internal fixation system with distal femoral locking plate. Data were introduced into reconstructed models of distal femur fracture in Mimics for grid division. Data were introduced into Ansys products 11.0 to construct finite element model, fix the surface of distal femur, and loaded 340 N on greater trochanter of femur. Stress distribution of each plate, screw hole and screw tail was analyzed in each group. Stress at the same region was compared in flexion and extension movement states. RESULTS AND CONCLUSION:(1) Finite element models of anatomic locking plate for distal femur fracture fixation were successful y established, total y 43 536 units, 41 256 nodes. (2) With the steel segment gradual y down (S1-S5), the stress gradual y increased. A1-A5 with the increase in the number of screws, the stress gradual y increased, but A6 suddenly decreased. (3) According to the cloud atlas of stress, these were wel distributed except A1. From distal end to extremity of screw, the stress of screws increased. Among corresponding segments, significant differences in stress around the nail holes and steel segment stress were detected. Moreover, the steel stress was greater than the stress of corresponding segment of screw hole. (4) Results suggest that using anatomical locking plate and minimal y invasive internal fixation system for distal femur fracture in a variety of fixed modes and moving conditions, the stress of each part is less than the yield strength of the titanium al oy screw, so the fixed system wil not produce instantaneous deformation or fracture.