## 4 Discussion  
This study revealed that wearable IMU-based sensors can be used to trace the knee angular motion with acceptable reliability. The wearable motion sensors were integrated with interactive mobile apps and telecommunication technology to assist postoperative rehabilitation after TKA, which helped patients easily and correctly follow a daily HE program under the remote supervision of a physician. Compliance with the daily exercise regime was enhanced, thereby improving the recovery of knee extension angle and quadriceps muscle power, which led to a higher maximal and average angular velocity in 5 TSST. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{4}{c}{**Positive Feedback**} & \multicolumn{2}{c}{**Suggestions**} \\ \hline
1. & This device helped me correctly and easily do daily exercises at home with a clear goal. & 1. & The calibration process for the sensors before exercise can be simplified. & be simplified. \\
2. & Because the doctor could trace my daily progress and interacted with me, I worked diligently to complete the assigned exercise tasks every day. I had no excuse for slacking. & 2. & Better to extend the battery standby time of the wearable sensors. \\
3. & My daily exercise performance records can be easily found on the app, helping me foster a sense of accomplishment and making me feel that I really have recovered well. & 3. & The app could have pre-recorded exercise videos to help users understand more easily. \\
4. & I could continue following the program and interacting with my doctor after surgery, making me feel that there was no distance from the doctor. & 4. & Rewards could be offered to the users for accomplishing the daily exercise tasks and making them more fun. \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Participant feedback for the overall MSD design. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{4}{c}{**B(SE)**} \\ \hline \multicolumn{4}{c}{**Dependent Variables**} & \multicolumn{4}{c}{**(Reference: Baseline)**} & \multicolumn{4}{c}{**(Reference: HE Group)**} \\ \cline{2-9}  & **1-Month** & _p-Value_ & **2-Month** & _p-Value_ & **Group at 1-Month** & _p-Value_ & **Group at 2-Months** & _p-Value_ \\ \hline Maximal angular velocity (\(\lx@math@degree\)/s) & 12.0 (4.0) & 0.003 & 13.5 (3.9) & 0.000 & 55.8 (17.5) & 0.001 & 66.3 (21.1) & 0.002 \\ \hline Average angular velocity (\(\lx@math@degree\)/s) & 7.2 (1.6) & 0.000 & 9.7 (2.0) & 0.000 & 23.2 (8.3) & 0.005 & 34.5 (12.5) & 0.006 \\ \hline \hline \end{tabular} Notes: VAS: Visual Analog Scale; WOMAC: Western Ontario and McMaster University Osteoarthritis Index; 5 TSST: five times sit-to-stand _test_.  
\end{table} 
Table 4: _Cont._ \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{4}{c}{**MAR Group**} & \multicolumn{2}{c}{**HE Group**} \\ \cline{2-5}
**Exercise Completion Rate** & **Recorded by Motion** & **Reported by** & **Reported by** & _p-Value_****a \\  & **Sensor Device** & **Participants** & **Participants** & **Participants** \\ \hline
1 month follow-up (\%) & 77.7 \(\pm\) 8.4 & 80.0 \(\pm\) 8.6 & 41.7 \(\pm\) 8.7 & 0.041 \\ \hline
2 month follow-up (\%) & 83.4 \(\pm\) 8.9 & 85.0 \(\pm\) 7.6 & 48.3 \(\pm\) 7.0 & 0.026 \\ \hline Overall (\%) & 80.6 \(\pm\) 8.2 & 82.5 \(\pm\) 7.7 & 45.0 \(\pm\) 7.2 & 0.041 \\ \hline \hline \end{tabular} Notes: \({}^{\textbf{a}}\) Comparison of the participant-reported exercise completion rates between the motion sensor-assisted rehabilitation and home-based exercise groups.  
\end{table} 
Table 5: Exercise completion rate reported by the participants and MSD. Home-based rehabilitation programs are a popular choice for patients following TKA. [PERSON] et al. developed a post-TKA home program comprising general aerobic components as well as general functional and muscle-specific exercises; they demonstrated that the supervised home program was cost-effective and as efficient as inpatient rehabilitation in facilitating mobility in patients after TKA [12].