### PCA Analysis  
We sought to perform a thorough data analysis that included all the elements in the database of the study. Of all the methods of statistical analysis, the method adopted by us was the principal component analysis (PCA) method. Figure 10 shows the results of the PCA method obtained at the initial time (Figure 10a) comparing the two groups of patients. It was observed that at the initial moment, the configuration of the factors was somewhat similar (Figure 10a,b). Thus, at the baseline, factor 1 had important contributions from the VAS test, muscle strength, and ROM flexion for the PG (Table 8), and for the CG, factor 1 had important contributions from the same factors (Table 3b). Notable differences were observed in the level of contributions of factor 2. While for the PG the age had an important contribution (Table 8), for the CG, age was already included predominantly in factor 3 (Table 9). \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Variable** & **Factor 1** & **Factor 2** & **Factor 3** & **Factor 4** & **Factor 5** & **Factor 6** \\ \hline Age (years) & \(-0.17544\) & \(-0.12843\) & \(0.800838\) & \(-0.40152\) & \(0.372737\) & \(-0.10588\) \\ \hline Weight (kg) & \(-0.38716\) & \(0.763855\) & \(0.261097\) & \(-0.09065\) & \(-0.16274\) & \(0.38502\) \\ \hline Height (cm) & \(-0.47821\) & \(0.638149\) & \(-0.0947\) & \(0.355641\) & \(0.32781\) & \(-0.34755\) \\ \hline Initial WOMAC test & \(-0.42858\) & \(-0.06762\) & \(-0.64829\) & \(-0.42846\) & \(0.422578\) & \(0.161166\) \\ \hline Initial VAS test & \(0.512754\) & \(0.487966\) & \(-0.17507\) & \(-0.56843\) & \(-0.24671\) & \(-0.2804\) \\ \hline Initial muscle strength & \(0.876851\) & \(0.101257\) & \(-0.01479\) & \(0.093\) & \(0.219449\) & \(-0.0209\) \\ \hline Initial ROM flexion test & \(0.802037\) & \(0.262331\) & \(0.026423\) & \(0.113245\) & \(0.342044\) & \(0.243706\) \\ \hline \end{tabular}
\end{table} 
Table 8: Factor coordinates of the variables based on correlations for the pilot group (PG) at the initial stage. Figure 10: PCA analysis results for the (**a**) pilot group and (**b**) control group at baseline (initial). For the following data set taken after 6 months of monitoring, the PCA diagram for the CG remained practically unchanged (Figure 12b) compared with the previous situations. For the PG, there were obvious changes (Figure 12a) in relation to the previous situation. In Figure 10a, if the PG presented important contributions for factor 2 from the VAS and WOMAC values, after 6 months of monitoring, the contributions of these factors were found in factor 3 (Table 12). For the PG, the height and weight parameters remained coupled and contributed to factor 2. This fact suggests that the body mass index would be extremely useful for analyzing the evolution of this group. \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Variable** & **Factor 1** & **Factor 2** & **Factor 3** & **Factor 4** & **Factor 5** & **Factor 6** \\ \hline Age & \(-0.057318\) & \(0.008466\) & \(-0.638977\) & \(-0.669853\) & \(0.248303\) & \(0.225369\) \\ \hline Weight & \(0.149165\) & \(0.80625\) & \(-0.236736\) & \(-0.067622\) & \(0.126056\) & \(-0.501077\) \\ \hline Height & \(0.146953\) & \(0.798468\) & \(-0.108744\) & \(0.317836\) & \(-0.052394\) & \(0.472586\) \\ \hline WOMAC test after 6 months & \(0.284124\) & \(-0.182385\) & \(-0.719375\) & \(0.11887\) & \(-0.590437\) & \(-0.075881\) \\ \hline VAS test after 6 months & \(0.301459\) & \(-0.344811\) & \(-0.498948\) & \(0.545593\) & \(0.4917\) & \(-0.030827\) \\ \hline Muscle strength after 6 months & \(-0.904867\) & \(0.072547\) & \(-0.240087\) & \(0.203629\) & \(0.006427\) & \(0.020377\) \\ \hline ROM flexion test after 6 months & \(-0.937252\) & \(0.016756\) & \(-0.162417\) & \(0.096187\) & \(-0.03038\) & \(-0.072024\) \\ \hline \end{tabular}
\end{table} 
Table 12: Factor coordinates of the variables based on correlations for the pilot group (PG) after 6 months. Figure 12: PCA analysis results for the (**a**) pilot group and (**b**) control group at 6 months.