The biomechanical study of hybrid stabilization with external fixator at femur fractures' intramedullar nailing

The femur bone is the strongest and longest bone in human body. Femoral shaft fractures are one of the most widespread injuries which need treating. There are two types of treatment techniques applied for the femur shaft fractures. The first technique is intramedullary nailing technique. With this technique, intramedullary nail is placed into the femur's marrow canal. Then it is screwed to the femur's proximal and distal ends. The second technique is external fixation technique. In this technique, a metal bar which is fixed to the femur with screws is placed outside the skin. These techniques have some drawbacks such as rotational and alignment instability. This study aims to decrease the disadvantages of these techniques, and to generate a new hybrid technique by using them. In this hybrid technique, the intramedullary nail inserted to the marrow canal and the external fixator are fixed to the proximal end of the femur via screws. At the femur's distal end, external fixator is attached to the femur, whereas the distal end of the intramedullary nail is free. In this study, a CT (computed tomography) scanned femur model was used. Intramedullary nailing, external fixation and hybrid techniques models were developed in Solidworks software. These models' finite element analyses were carried out in ANSYS software. Axial compression and torsion tests were applied to models. Stress distribution and total deformation on the femur and treatment materials were investigated. In conclusion, hybrid technique's rotational and alignment stability was found to be more stable than the other techniques.