## 4 Discussion  
The current study expands the knowledge base by providing a more nuanced understanding of the biomechanics involved in proximal femoral nailing (Figures 3 and 6). For instance, a significant correlation between Pauwels angle and stress distribution has been discovered. This finding supports the Pauwels hypothesis that the Pauwels angle correlates with instability and increased shear forces, thus influencing the overall prognosis of the patient [22]. This study confirms this and offers biomechanical evidence supporting the clinical observations made in previous studies [23]. Similar studies have shown that the Pauwels angle is an important factor in the failure of fixation. The Pauwels angle produces high shear forces on the screws used for fracture stability. Similar results have been encountered in many studies, and the use of multiple screws has been recommended in Pauwels type II fractures, since the fracture line and the femoral neck axis are perpendicular to each other, thus avoiding shear force [24; 25; 26]. In the literature, it has been observed that with an increasing Pauwels angle, vertical shear forces in femoral neck fractures increase and stabilization of internal fixators occurs [7; 27]. Therefore, determination of the optimal Pauwels angle has become important.  
On the other hand, this study found that the rotational and translational parameters of the screw (Translate 1, 2, and 3) do not significantly affect stress distributions at the fracture  
Figure 6: The sensitivity levels of the input parameters on the stress values occurring in some regions on the system.  
surfaces. These findings challenge conventional wisdom regarding screw positioning and could have profound implications for surgical planning. Despite the emphasis placed on the exact screw positioning, the benefit may be marginal due to the inherent angular stability of modern cannulated screws. In similar studies, it is seen that the importance of each screw for fracture stability is different [6]. In this study, the posterior TSC was found to present a lower maximum equivalent von Mises stress value (occurring in screw No. 3) than the inverted TSC. In this study, a result confirming this information was obtained. Considering the stresses on the screws, it is seen that the values occurring in the posterior TSC are lower than those occurring in the inverted TSC (occurring in screw 2, Figure 4). In addition, when the stresses on all three screws are considered together, the most suitable configuration is the inverted triangle configuration when the Pauwels angle is \(54^{\circ}\) and the Translate value is \(7\) mm (Figure 5). As a result of different evaluations, it is seen that there is not much of a difference between the posterior triangular screws and the inverted triangular screws [6, 28]. When the minimum values of the stresses occurring on the screws are considered in Figure 4, it is seen that the Translate value of all three screws is approximately \(7\) mm. Similar studies have shown that the distance from the inner surface of the screws to the cortex of the femoral neck should be less than \(3\) mm in screw fixation of FNFs. They also stated that the closer the screws are to the inner surface of the cortex of the femoral neck, the more favorable the healing at the fracture site [29, 30]. In this study, Figure 4, the values of the Translate values near the femoral neck cortex are close to approximately \(7\) mm. Importantly, the von Mises equivalent stresses on the cannulated screws were investigated. As highlighted by [31], hardware failure is a significant contributor to poor outcomes in FNFs. By assessing the mechanical stress on the screws, this study offers insights that can contribute to the design and selection of more robust and efficient orthopedic hardware. This study can be further analyzed by comparing different Pauwels angles with femoral neck systems and four cannulated screws [32].