## 4 Discussion  
In the last 10 years, VRBR has been employed as a rehabilitative tool in the recovery of TKA with promising results [70], including teaching future orthopedic surgery doctors to perform TKA [71]. The increased scientific production related to the topic has motivated previous reviews to be published [7; 35; 36; 37]. To complement these reviews and update the scientific knowledge about the use of VRBR on TKA, our meta-analysis aimed to assess the effect of VRBR in improving knee pain, knee function, balance, knee flexion ROM and extension strength, gait speed, aerobic capacity, and functional independence after TKA. Secondarily, we want to assess if the effect of VRBR will be maintained at 3 and 6 months after the end of VRBR; if VRBR is more effective when it is used as isolated therapy or combined with CT; and finally, whether the VRBR modality (immersive or non-immersive) is more appropriate for each variable. Our meta-analysis included 12 RCTs that provided data from 997 patients who recently received TKA with a mean age of 70 years old (62% female). This systematic review with a meta-analysis is a review with several studies included. Our meta-analysis includes the last two recently published RCT [63; 69] and provides meta-analyses of variables not assessed until our study, such as knee flexion ROM and extension strength, gait speed, functional independence, and aerobic capacity. The main findings of our study showed that VRBR is effective in improving knee pain and function, dynamic balance and knee flexion ROM and extension strength, in comparison with CT. Subgroup analysis revealed that the effect of VRBR may be maintained at 3 months for knee pain and at 3 and 6 months for knee function. The combined use of VRBR plus \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Study** & **Advantages** & **Disadvantages (Side Effects)** \\ \hline \hline \multirow{6}{*}{[PERSON] et al., 2020 [58]} & Total adherence to non-immersive VRBR was reported by 88.3\% of patients and 65.4\% in the CT group. VRBR would be recommended by 83.3\% of patients who used it. Patients in non-immersive VRBR were satisfied with the therapy. & Not reported \\  & Not reported & Not reported \\  & Patients of the non-immersive VRBR group reported high values of ease of use, learnability, satisfaction, and recommendations for future use. Patients in the non-immersive VRBR group showed good & Not reported \\  & Not reported & Not reported \\  & Patients in both groups (non-immersive VRBR and CT) showed high satisfaction with the therapy. However, patients reported enjoyment using non-immersive VRBR, opposite to CT, related to the major motivation to participate in the virtual exercise. & Not reported \\  & Patients in the non-immersive VRBR group reduced the frequency in consumption of medicaments, although no statistically significant differences were found between groups. & More dropout rates in the non-immersive VRBR group due to participants feeling \\  & Immersive VRBR reduced the time needed to increase knee ROM. & Not reported \\  & Not reported & Not reported \\  & Not reported & Not reported \\  & Patients reported that non-immersive VRBR was comfortable, pleasant, useful, and recommendable for other patients and themselves in the future. In addition, they showed a low level of knee pain during therapy. In general, patients were satisfied with the non-immersive VRBR. Patients in the CT group showed low acceptability and satisfaction. & Not reported \\  & Not reported & Not reported \\  & Not reported & Not reported \\  & & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Advantages and disadvantages of VRBR in the studies included. CT is more effective in improving knee pain and knee flexion ROM, and for reducing knee pain, immersive VRBR may be more effective, while non-immersive VRBR can be more recommended in improving dynamic balance. In addition, patients who performed VRBR reported large levels of satisfaction and adherence to VRBR, especially to non-immersive VRBR.