## 2 Materials and Methods
### Stage Three: The Hybrid Stem Design Process
#### 2.3.2. Generating a Stem Proposal  
The multi-objective analysis applied to generate the stem proposal was carried out using 16 reference points (eight on the medial side \"M\", and eight on the lateral side \"L\") placed on both sides of the hip implant. To set the reference, four planes containing the lines M1-L1, M3-L3, M5-L5, and M7-L7, were created around an angle of 35\({}^{\circ}\) using the baseline, and parallel lines from it, replicating the views presented by [PERSON] et al. [9]; the remaining planes (M2-L2, M4-L4, M6-L6, and M8-L8) were placed in the middle of the  
\begin{table}
\begin{tabular}{l l l l l l l l l l l l l l l l} \hline \hline  & \multicolumn{4}{c}{**Maximum Equivalent Stress (von Mises)**} & \multicolumn{4}{c}{**Maximum Equivalent Strain (von Mises)**} \\ \hline  & \multicolumn{4}{c}{**Medial**} & \multicolumn{4}{c}{**Lateral**} & \multicolumn{4}{c}{**Medial**} & \multicolumn{4}{c}{**Lateral**} \\ \hline
**Stem** & **Location** & \(\sigma\) **(MPa)** & **Material** & **Stem** & **Location** & \(\sigma\) **(MPa)** & **Material** & **Stem** & **Location** & \(\epsilon\) **(mm/m)** & **Material** & **Stem** & **Location** & \(\epsilon\) **(mm/m)** & **Material** \\ \hline P2-T & M1 & 340.08 & SS316L & P2-T & L1 & 189.18 & SS316L & P2-T & M1 & 1.55 & SS316L  
planes mentioned above. The numbering of the points starts at the reference line located at the block's top surface and goes up to the stem neck (Figure 4a). As a result, new points were generated (Figure 4b) on both the medial and lateral sides. The next step was to place the new reference points in a plane using their coordinates, corresponding profiles and cross-sectional areas (Table 5). Finally, the hybrid profile (Figure 4c) was drawn by linking the new reference points described above. Those points aided in defining the radii and angles of the profile to generate the solid. It is important to highlight that the trapezoidal cross-sectional area was the geometry with the best results, which agrees with the findings of Appendix A and the results reported by [PERSON] et al. [2], [PERSON] et al. [9], and [PERSON] et al. [28].  
Figure 4: (a) Locations of 8 points in the medial side and 8 points in the lateral side of the implant. (The number of points increases upwards in both parts of the implant, M1 “Medial 1” and L1 “Lateral 1”). (b) Locations of the points that showed the best stress and strain results of the different stems evaluated, where (MX/LX \(\rightarrow\) PX-T) represents the path assessed at each of the generated reference points (M1-M8 and L1-L8); P1, P2, and P3 represent the profile numbers; and the letter represents the type of cross-section (T = trapezoidal). (c) Design implant proposal. (d) Maximum stress with the hybrid profile using the load of activity 4 (Down stairs) and the stainless steel material (SS316L).  
2.3.3. Analysis with ASTM F2996-13 and ISO 7206-4-2010(E)  
Finally, another study was carried out on the hybrid implant using the ASTM F2996-13 (see Figure 5) and the loading conditions of the ISO 7206-4: 2010 (E) [28], to observe the performance of this design with respect to the other configurations (P1, P2 and P3 with the circular cross-sectional area, ellipse, oval, and trapezoidal).