2022, Vol. 26 ›› Issue (36): 5775-5780

Finite element analysis of femoral neck system for adult Pauwels III femoral neck fracture

Yang Tongchi1, Hu Juzheng1, Wang Renchong1, Xie You1, Chen Fanglin1, Wen Dingfu1, Shi Zhanying2   

Abstract: BACKGROUND: There is no consensus on the choice of internal fixation for Pauwels type III femoral neck fractures.
OBJECTIVE: To analyze biomechanical characteristics of femoral neck system in the treatment of adult Pauwels type III femoral neck fracture by three-dimensional finite element method, providing theoretical basis for its application in clinical practice.
METHODS: The model of Pauwels type III femoral neck fracture was established by using CT images of volunteers, and four internal fixation models were established: four cannulated compression screws, biplane double-supported screw fixation, percutaneous compression plate, and femoral neck system. The internal fixation model and femur model were assembled according to common clinical fixation methods. Finally, Ansys software was used for loading and calculation to analyze the stress distribution, stress peak value, and maximum displacement of femur and internal fixation in each model.
RESULTS AND CONCLUSION: (1) The stress of the proximal femoral fracture is mainly distributed in the lower part of the femoral neck near the talus femur. The stress peak of four-cannulated compression screw group was the largest and that of femoral neck system group was the smallest. (2) The displacement peak of four-cannulated compression screw group was the largest and that of femoral neck system group was the smallest. (3) The displacement peak of percutaneous compression plate group was the largest and that of biplane double-supported screw fixation group was the smallest. (4) The internal fixation stress was mainly distributed on the surface of the internal fixation device near the fracture surface. The stress peak of percutaneous compression plate group was the largest and that of four-cannulated compression screw group was the smallest. (5) The displacement peak value of percutaneous compression plate group was the largest and that of biplane double-supported screw fixation group was the smallest. (6) Above results concluded that compared with other three groups, the femoral neck system showed smaller proximal fracture mass stress and displacement, more uniform and dispersed stress distribution, and better force conductivity. In addition, biplane double-supported screw fixation internal fixation has the smallest displacement peak, but the internal fixation stress is greater than femoral neck system, and the stress is relatively concentrated, which may lead to screw fracture. The experimental results show that the femoral neck system has better biomechanical stability and can create a better mechanical environment for fracture healing.
Key words: femoral neck, femoral neck fracture, internal fixation, finite element analysis, biomechanics