# A Review on Upper Limb Rehabilitation Robots
## 2 Rehabilitation Treatments
### Bilateral Therapy  
Bilateral therapy refers to the mirroring principle in performing rehabilitation [4]. Where the impaired limb copies the movement of the functional limb (Figure 3), this gives the user whole control of the affected limb [20; 21].  
Mirror image movement enabler (MIME) and a few other exoskeletons employ bilateral therapy [22]. A clinical study on the bilateral therapy mode was performed by [23]; fourteen subjects were involved in the study and obtained professional training of the therapy. The study consisted of thirty-one sessions distributed over two months; nevertheless, the study was performed in the first six months after a stroke. The results showed a significant improvement in the impaired hemisphere and motor functions [9].  
It was noticed that each therapy is dedicated to specific conditions and mainly depends on the patient's ability. Table 1 summarizes the therapy types in terms of targeted patients, therapy procedure and limitations. In addition, Table 2 was added to summarize the therapy types in terms of clinical results.  
Figure 2: Represents patient trying to perform the abduction and the adduction of the upper limb. The weight helps the patient to perform the abduction which represents the Active-Assistive therapy. Also, the weight prevents the patient performing the adduction which represents Active-Resistive therapy.  
_Appl. Sci._**2020**, _10_, 6976  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
\begin{tabular}{c} Beneficial for upper \\ limb extremities \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 1: Summary of the therapy types in terms of targeted patient, therapy procedure and limitations.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Source** & **Therapy Type** & \begin{tabular}{c} **Post-Stroke** \\ **Time** \\ \end{tabular} & \
\begin{tabular}{c} **No. of** \\ **Subjects** \\ \end{tabular} &
\begin{tabular}{c} **No. of** \\ **Sessions** \\ \end{tabular} & **Improvements** \\ \hline
[15] & Passive & \textless{}6 months & 3 & \
\begin{tabular}{c} 1 session \\ 40 min \\ \end{tabular} &
\begin{tabular}{c} Reducing the spasm and the \\ stiffness of the impaired limb \\ \end{tabular} \\ \hline
[9] & Active-Assistive & \textgreater{}6 months & 8 & \
\begin{tabular}{c} 18 sessions \\ 6 weeks \\ 1 h/workday \\ \end{tabular} &
\begin{tabular}{c} Results showed an improvement \\ in the impaired joints \\ \end{tabular} \\ \hline
[19] & Active-Resistive & \textgreater{}6 months & 8 & \
\begin{tabular}{c} 18 sessions \\ 6 weeks \\ 1 h/workday \\ \end{tabular} &
\begin{tabular}{c} Results showed an improvement \\ in the long-term strength \\ \end{tabular} \\ \hline
[23] & Bilateral & \textless{}6 months & 14 & \
\begin{tabular}{c} 31 sessions \\ 8 weeks \\ 1 h/workday \\ \end{tabular} &
\begin{tabular}{c} Results showed an improvement \\ of the impaired hemisphere and \\ motor functions \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 2: Summary of the therapy types in terms of the clinical results.  
Figure 3: Shows an example of bilateral therapy, where one of the limbs is functional, and the other is impaired. The patient has the ability to freely move the functional limb, and the impaired one follows this movement.