Fatigue behaviors of different materials for schanz screws in femoral fracture model using finite element analysis

In the daily life, human beings may be met with a number of undesired traumas. As a result, intertrochanteric fractures can occur in the skeletal system. Intertrochanteric femoral fractures are serious traumas that can lead to pneumonia, pulmonary embolism or death. Therefore, fixing as accuracy and stabilty of these fractures is necessary. The schanz screws with pertrochanteric fixator body are used for stabilizaiton of intertrochanteric fractures. Fatigue behaviors of the schanz screws must be longer than the duration of fracture consolidation. The aim of this study is to determine whether there are differences between fatigue behaviours of different materials for schanz screws when they are used for intertrochanteric femoral fracture fixation. Fatigue behaviors of schanz screws used for fixing of intertrochanteric fractures were analysed with ANSYS Workbench software using finite element analysis under dynamic loads for stainless steel and titanium. After the analysis, minimum fatigue life has been determined as approximately 21 months for the schanz screws having stainless steel while titanium has been determined as approximately 2 months. In addition, safety factor for schanz screws having stainless steel is calculated as 1.36 whereas safety factor for titanium is calculated as 1. Therefore, considering the consolidation of an intertrochanteric femoral fracture with a mean duration of three months, the titanium schanz screws shouldn't be used since their fatigue behavior is two months and safety factor is less than stainless steel.