## 3 Results  
Precision and accuracy values of the 3D\({}_{\text{wear}}\) approach were all within the range of a hundredth of a millimeter. Values were below 0.054 mm (precision) and 0.025 mm (accuracy), respectively, for the three wear protocols. In comparison to 2D\({}_{\text{wear}}\) methodology, these values were all within the range of a tenth of a millimeter, below  
The wear results of the 3D\({}_{\text{wear}}\) approach did not change significantly with a change in pelvic position (Figure 4). Significant changes in wear results could be identified only for the pelvic lateral tilted left 5 deg position relative to the pelvic neutral position (\(p<0.05\)). The 2D\({}_{\text{wear}}\)\(p\) values illustrated a contrary picture to the findings for 3D\({}_{\text{wear}}\). With the exception of the pelvic lateral tilted left 5 deg position and the pelvic rotated left 5 deg position, the remaining four pelvic positions showed significantly different wear results (\(p<0.05\)) relative to the pelvic neutral position.  
The assessment for interchangeable applicability of the 2D\({}_{\text{wear}}\) next to the 3D\({}_{\text{wear}}\) wear approach within the neutral pelvic position scenario indicated the largest range of the LoA for high wear group. LoA ranged from a minimum of \(-0.16\) up to 0.49 mm (mean difference: 0.16 mm), as well as from a minimum of \(-0.06\) up to 0.20 mm (mean difference: 0.07 mm) for the low wear group, respectively (Figure 5). For different pelvic orientations, the largest LoA was observed in the high wear group, with values ranging from \(-1.06\) to 1.36 mm (mean difference: 0.15 mm) within the pelvic lateral tilted right 5 deg position (Table 3). The lowest LoA existed in the medium wear group and was from \(-0.24\) to 0.25 mm (mean difference: 0.00 mm) within the pelvic rotated left 5 deg position. In general, LoAs were increased for changed pelvic positions relative to the neutral position within all the wear groups.  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **2D\({}_{\text{wear}}\) [mm]** & **3D\({}_{\text{wear}}\) [mm]** \\ \hline In total & 0.206 & 0.043 \\ Low & 0.107 & 0.033 \\ Medium & 0.154 & 0.038 \\ High & 0.304 & 0.054 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Precision (SD) of overall and individual wear groups in 2D\({}_{\text{wear}}\) and 3D\({}_{\text{wear}}\).  
Figure 4: Box plot between 2D\({}_{\text{wear}}\) and 3D\({}_{\text{wear}}\) (the \(x\)-axis reveals different wear positions, and the \(y\)-axis reveals the difference between the measurement value and true value. The blue and brown boxes illustrate 2D\({}_{\text{wear}}\) and 3D\({}_{\text{wear}}\), respectively. Stars (*): \(p<0.05\)).  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **2D\({}_{\text{wear}}\) [mm]** & **3D\({}_{\text{wear}}\) [mm]** \\ \hline In total & 0.159 & 0.017 \\ Low & 0.146 & 0.025 \\ Medium & 0.069 & 0.011 \\ High & 0.263 & 0.016 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Accuracy (bias) of overall and individual wear groups in 2D\({}_{\text{wear}}\) and 3D\({}_{\text{wear}}\).  
Figure 5: [PERSON]–Altman [28] scatter plots in the pelvic neutral position between 2D\({}_{\text{wear}}\) and 3D\({}_{\text{wear}}\) for (**a**) the low wear group (**b**) the medium wear group and (**c**) the high wear group. Each data point of the plots presents the computed differences between the 2D\({}_{\text{wear}}\) and 3D\({}_{\text{wear}}\) approach (ordinate), which is plotted versus the mean difference (abscissa) of both methods, respectively. LoA is visualized by the horizontal lines, representing the mean value of calculated differences, and the two dashed lines (mean \(\pm\) 1.96 SD) represent bounding criteria.