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BackgroundIn the present study, we evaluated the mechanical outcome of different configurations formed by fully threaded screws and partially threaded screws in the treatment of unstable femoral neck fracture.MethodsThe Pauwels type III unstable femoral fracture and the models of the fully threaded screw and partially threaded screw were constructed in 3-matic software and UG-NX software respectively. We then assembled the different screw configurations to the fracture model separately to form the fixation models. After meshing the models’ elements, we used Abaqus software to perform the finite element analysis. Parameters of von Mises stress distribution on the screws, peak stress, displacement between fracture fragments, and model principal strains in cancellous bone were reported.ResultsOur results indicated that the peak von Mises stresses of screws was concentrated in the middle surface of the screw near the fracture line in each group. Peak stress value of the implants was highest in the model of triangle with posterior single screw. And the lowest stress values were observed in the triangular model. Fully threaded screw in each group underwent the most stress while partially threaded screw underwent a little bit of stress. Lowest displacement was observed in the triangular model. The volume of bone susceptible to yielding in the femoral neck region was the lowest for triangular configuration.ConclusionsFor unstable femoral neck fractures, superior results were obtained by stabilizing the fracture with triangular configuration formed by one superior partially threaded screw and two inferior fully threaded screws. This study will require clinical confirmation as to its practicality in the management of unstable femoral fractures.

Objectives In the present study, we evaluated the mechanical outcome of different configurations of cannulated compression screws for the fixation of Pauwels type III femoral neck fracture and the stress distribution around the holes corresponding to fixation protocol after screws removal. Methods The Pauwels type III of femoral neck fracture was created in 3-matic software and the models of cannulated compression screws were constructed using UG-NX software. Five fixation systems were assembled to the fracture models. Abaqus software was used to perform the process of finite element analysis. Values of stress distribution, maximum stress, model principal strains of proximal fragment, and stress distribution around the holes of femur model were recorded. Results Stress of cannulated compression screws was intensely focused on the middle area of the screw near the fragment of each group. Inverted triangle model showed the highest peak stress on screws under different phases of load. Each screw dispersed some stresses, but at least one underwent the peak stress. Fracture model fixed by inverted triangle configuration showed the lowest volume of yielding strain in the proximal fragment. The area of higher stress around the holes was largest after triangle screws removal when compared with other four models. Conclusions Our study indicated that different cannulated compression screws fixation configurations for the unstable femoral neck fractures showed the different mechanical efficiency. Inverted triangular configuration showed the mechanical advantage and being less likely to cutout. The fixation strategy of triangle configuration was least recommended if patients tended to remove the implants.