A comparison between cannulated and non-cannulated cancellous screws used in the fixation of a simulated femoral neck fracture - a finite element study
Lee, Guo Xiang
Date of Issue2016-05-25
School of Mechanical and Aerospace Engineering
Previous studies have been done on the performance of different screw designs and configurations. These are based on the pull-out strength of the screws and the best fixation based on load, stiffness and displacement characteristic. However, there is not much study done on the use of finite element method to investigate the various fixations. In this study, Abaqus was used to compare the results between cannulated screws and non-cannulated screws used in an inferior triangular fixation on Pauwel’s type-2 vertical femoral neck fracture. The model was modelled after a Sawbone femur. Loading of 2000 N were used. The von Mises stresses were analysed and compared with the yield stress. The cortical bone of the cannulated screw fixation stress value is 154.2 MPa while the cortical bone of the non-cannulated screw fixation stress value is 136.8 MPa. The cannulated screw stress value is 1593 MPa while the non-cannulated screw stress value is 1746 MPa. This results suggest that the non-cannulated screws are able to withstand a greater load than cannulated screws. However, the results obtained were unrealistic comparing with the yield stresses. As such, lower loading of 650 N and 1000 N were used to run the simulations. The maximum von Mises stress values for cortical bone, cannulated screws and non-cannulated screws increased with increased loading other than the third cannulated screw which stress value decreases when loading increased from 1000 N to 2000 N. It is likely the screw had failed and this causes a load shift.
Final Year Project (FYP)
Nanyang Technological University