## 3 Results
### STHA--Templating in Two Planes--a.p. and Lateral View  
Adding a second plane (lateral view according to \"Lauenstein\"), the rate of planning the exact size reached 50.0% \(\pm\) 27.5%. The predictability was 89.9% \(\pm\) 12.0% with a tolerance of variation of +/\(-\)1 stem size. A variation of the implanted stem size lay within a range of +/\(-\)2 sizes in 98.2% \(\pm\) 3.2% of the cases (Table 1). A deviation of \(\pm\) 3 stem sizes was observed in the remaining measurement except for one outlier in one patient \begin{table}
\begin{tabular}{c c c c c c} \hline \multicolumn{2}{c}{**Difference in Templated Size Compared to the**} & \multicolumn{1}{c}{**0**} & \multicolumn{1}{c}{**+/\(-\)1**} & \multicolumn{1}{c}{**+/\(-\)2**} & \multicolumn{1}{c}{**+/\(-\) 2**} \\ \multicolumn{2}{c}{**Truly Implanted Prosthesis**} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \\ \hline \multirow{4}{*}{\begin{tabular}{c} **CTHA** \\ **(Templating a.p.)** \\ \end{tabular} } & **Rater 1** & 52.0\% & 82.0\% & 90.0\% & 100.0\% \\  & **2** & 39.1 & 89.1 & 91.3 & 100.0 \\  & **3** & 42.0 & 94.0 & 100.0 & 100.0 \\ \cline{2-6}  & **Mean \(\pm\) Standard Deviation** & **44.4 \(\pm\) 6.8** & **88.4 \(\pm\) 6.0** & **93.8 \(\pm\) 5.4** & **100.0 \(\pm\) 0** \\ \hline \multirow{4}{*}{\begin{tabular}{c} **CTHA** \\ **ing 2 Planes** \\ \end{tabular} } & **Rater 1** & 64.0\% & 96.0\% & 100.0\% & 100.0\% \\  & **2** & 26.1 & 78.2 & 97.8 & 100.0 \\  & **3** & 30.0 & 94.0 & 100.0 & 100.0 \\ \cline{2-6}  & **Mean \(\pm\) Standard Deviation** & **40.0 \(\pm\) 20.8** & **89.4 \(\pm\) 9.8** & **99.3 \(\pm\) 1.3** & **100.0 \(\pm\) 0** \\ \hline \multirow{4}{*}{\
\begin{tabular}{c} **STHA** \\ **(Templating a.p.)** \\ \end{tabular} } & **Rater 1** & 45.0\% & 83.0\% & 99.0\% & 100.0\% \\  & **2** & 16.7 & 78.9 & 100.0 & 100.0 \\  & **3** & 47.0 & 97.0 & 100.0 & 100.0 \\ \cline{2-6}  & **Mean \(\pm\) Standard Deviation** & **36.2 \(\pm\) 16.9** & **86.3 \(\pm\) 9.5** & **99.7 \(\pm\) 0.6** & **100.0 \(\pm\) 0** \\ \hline \multirow{4}{*}{
\begin{tabular}{c} **STHA** \\ **ting 2 Planes** \\ \end{tabular} } & **Rater 1** & 60.0\% & 93.0\% & 100.0\% & 100.0\% \\  & **2** & 18.9 & 76.7 & 94.5 & 100.0 \\  & **3** & 71.0 & 100.0 & 100.0 & 100.0 \\ \cline{1-1} \cline{2-6}  & **Mean \(\pm\) Standard Deviation** & **50.0 \(\pm\) 27.5** & **89.9 \(\pm\) 12.0** & **98.2 \(\pm\) 3.2** & **100.0 \(\pm\) 0** \\ \hline \end{tabular}
\end{table} 
Table 1: Cumulative percentages of the three raters for the conventional (CTHA) and short stem total hip arthroplasty (STHA) groups, using one and two planes, separated in accordance with the variation between the real stem size and the measured size while templating. measured by one rater and showing a deviation of 4 stem sizes. In 31.8%, oversizing and 18.3%, undersizing of the templated size compared to the implanted size was measured. Overall, the difference between the implanted stem size and the templated size showed a lesser deviation for the STHA planned on two planes compared to one plane, whereas the deviation was rather constant for the CTHA. However, this potential effect did not reach statistical significance. In addition, there was a trend that bigger implant sizes were planned too small, while small stem sizes were planned too big (Figure 4). An additional plane for preoperative stem templating led to an increase in the ICC for the stem size as well as for the difference between the implanted and templated stem size, except for the STHA difference values, where a decrease was observed (Tables 2 and 3). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Stem Size** & **CTHA** & **STHA** \\ \hline
**a.p. planning** & 0.774 & 0.736 \\
**a.p. + lateral planning** & 0.838 & 0.757 \\ \hline
**Difference to Implanted Size** & **CTHA** & **STHA** \\ \hline
**a.p. planning** & 0.586 & 0.483 \\
**a.p. + lateral planning** & 0.623 & 0.422 \\ \hline \hline \end{tabular}
\end{table}