LAUSR

OBJECTIVE The aim of this study was to determine the ideal placement of the lag screw taking into account the fracture morphology in the sagittal plane. MATERIALS AND METHODS Three different morphology of fractures were created on the sagittal plane in femur models obtained in 3D CT scanning: posteriorly angled (Type A), transverse (Type B) and anteriorly angled (Type C). The lag screw was applied in each of the three fracture morphology as neutral, anteverted and retroverted in the sagittal plane. The nine models created were transferred to the Ansys Workbench program and analyzes were performed. RESULTS In Type A fracture, the stress value at the lag screw apex increase as the lag screw placement changes from the anteverted position to the retroverted position. It decreases in the Type B and Type C fractures. As the lag screw placement is changed towards the anteverted position, the stress at the lag screw-nail junction decreases in the Type A fracture and increases in the Type C fracture . There is no significant change in the Type B fracture. As the lag screw placement is changed towards the anteverted position, the stress in the calcar region increases in Type A fractures and decreases in Type C fractures. There is no significant change in type B fractures. CONCLUSION While the ideal lag screw placement in a type A fracture in the sagittal plane is the retroverted placement, the anteverted placement is ideal placement in type C fractures. Fracture morphology in the sagittal plane should be taken into account in the lag screw placement.