Comparison of parallel or convergent proximal schanz screw placement of pertrochanteric fixator in intertrochanteric fracture model

Intertrochanteric femoral fractures are serious traumas among elderly patients. In these patients, external fixator is a preferable method for the fixation of fractures. Therefore, this study was planned to compare the parallel and convergent proximal schanz screw placement of pertrochanteric fixator in the intertrochanteric femoral fractures with respect to biomechanical forces that stabilize the fracture line and to present their clinical importance. A commercial finite element based program, AnsysWorkbench was used to investigate the biomechanical parameters of the femoral intertrochanteric fractures and different placement of implants. The von Mises stress, von Mises strain and shear stress on the proximal and distal surface of the fracture line were lower in the convergent pertrochanteric fixator. Proximal schanz screws in convergent configuration pertrochanteric fixator had greater stress and strain values than proximal schanz screws in parallel configuration pertrochanteric fixator. The distance between the proximal schanz screws on the fracture line was measured as 12 mm in convergent configuration pertrochanteric fixator, and as 3.5 mm in parallel configuration pertrochanteric fixator. The angle between the proximal schanz screws in the convergent configuration was measured as 12.88°. The effect of convergent and parallel configuration pertrochanteric fixators on axial loading demonstrated that convergent configuration pertrochanteric fixator was safer in this respect.