## 3 Results and Discussions  
### Results for Configuration with Gap--Initial Stage  
The EF strength and stiffness results for the scenario without any callus formation (with a fracture gap) are presented in Table 2 for 0.1 g, 0.5 g, and 1 g loads, where g is the gravitational force equivalent for a 70 kg male expressed in N as explained in Section 2.4.1, corresponding to the sit-down position, two-legs stance, and one-leg stance cases. The stress levels, safety factors under 1 in Table 2, exceed the allowable limit of the respective components. Acceptable results were observed only for the 0.1 g case with a 500 N wire pre-tension. In the 1000 N pre-tension case, all stress values remained within limits except for the EF ring, which exceeded the allowable threshold. Moreover, a progressive increase in the Y displacement was noted with both higher applied loads and increased  
Figure 9: Ring–only boundary conditions for both metallic and PLA–CF configurations: (**a**) boundary conditions applied to the metallic ring model with 500 N pre-tension in three wires (B–D) and one fixed node (A) for isostatic constraint. ; and (**b**) directional deformation along the \(Z\)-axis for the PLA ring under 100 N pre-tension, shown for two configurations. wire pre-tension. This behavior is attributed to the pin placement, which is 121 mm away from the fracture site. The sliding of the pins, combined with this positioning, induces a rotational movement at the fracture location, contributing to the observed displacements. Applying wire pre-tension was shown to reduce the VM stress in the wires and clamps for both the two-leg and one-leg stance cases, while also lowering the stress in the bone. However, an increase in VM stress was observed in the pins, rods, and EF ring as the pre-tension increased. Regarding the PLA-CF ring configuration (Table 3), only the case without wire tension and with 100 N of wire tension were analyzed, as the calculations for a wire pre-tension of 500 N or higher failed to converge, due to excessive deformations, which led to element distortion in the simulation. For the PLA-CF ring configuration, compared to the metallic counterpart, stiffness is reduced by 25% under 0.1 g axial loading and by 21% with wire pre-tension applied, becoming half of the metallic configuration stiffness under 1 g axial loading. In terms of strength, the VM stress levels in the PLA-CF components remain below 42 MPa, regardless of the applied axial load (Figure 10). To further validate these findings, additional research should explore the effects of higher wire pre-tension on the structural behavior of PLA-CF rings. As presented in Figure 11, EF stiffness increases with the applied wire pre-tension, a trend that is also confirmed by the findings in [3]. The Z displacement increases with the axial applied load, though not in a perfectly linear manner. This deviation can be attributed to sliding effects at the bone-to-pin and bone-to-wire contact interfaces, which influence the overall displacement behavior. For both the metallic and PLA-CF EF configurations, achieving an early weight-bearing capability immediately after surgery is not feasible. The patient should remain in full bed rest for a period to allow for callus formation and the initial healing of the fracture gap. Although the 0.1 g load case without wire pre-tension results give acceptable stress levels across all components, it is not considered viable because the axial displacement exceeds 33% of the initial 3 mm gap size, making it structurally insufficient. Therefore, a minimum of 500 N wire pre-tension is required. For the 1000 N pre-tension case, all stress values remain within allowable limits except for the EF ring, suggesting that a ring redesign is necessary in order to accommodate higher preloads. Figure 10: PLA-CF EF—VM stress—the scenario with gap and 100 N pre-tension.