# Development of an Ergonomic Writing Assistive Device for Finger Pain Reduction in the Elderly
## 4 Discussion  
An ergonomic WAD was developed to reduce finger pain for the elderly by improving the fixing power, grip method, material, size, and weight of existing WADs. In order to confirm the effectiveness of the NDWAD, a handwriting experiment was conducted, comparing it to the existing WADs SW and WB. Muscle activity and finger pressure generated during the handwriting experiment were measured, and after the experiment, the satisfaction level associated with the use of each WAD was investigated through modified version of the QUEST 2.0. questionnaire. Among the measured average muscle activity results of the hand and wrist, we noted significant differences in APB related to thumb abduction and FDI related to abduction/adduction and flexion of the index finger. Both APB and FDI were the lowest in WB, while SW and NDWAD showed similar muscle activity. The NDWAD was designed to be used as the dynamic tripod grip, which is the most popular grip method. The SW can also be used in the dynamic tripod method. It can be confirmed that the developed NDWAD was properly designed because the muscle activity was similar when using SW and NDWAD based on the same grip method. In addition, in this study, it was determined whether the shape and grip method of the WAD affect the muscle activity related to writing. In WB, the activity of APB and FDI was significantly decreased compared with SW and NDWAD. SW and NDWAD use a dynamic tripod grip with a lot of thumb and index finger movement, while WB uses a grip similar to holding a computer mouse. From these results, it was confirmed that the shape and grip method of the WAD affect the muscle activity. Although the activity of FPL involved in thumb flexion was not significant, it was highest in the NDWAD, and similar muscle activity was shown in SW and WB. It is suggested that this difference in muscle activity occurred as a result of the continuous flexion of the thumb as the NDWAD design considering the flexion and position of the thumb. No significant difference in the results of each WAD was found for EIP involved in index finger \begin{table}
\begin{tabular}{c c c} \hline \hline
**Complaint** & **SW** & **WB** & **NDWAD** \\ \hline Dimension & 5\% & 15\% & - \\ Weight & - & 5\% & - \\ Safety & - & 5\% & - \\ Durability & 5\% & 5\% & - \\ Easy to use & 30\% & 65\% & - \\ Comfort & 15\% & 40\% & - \\ Effectiveness & 25\% & 70\% & 5\% \\ Use again & 35\% & 60\% & 10\% \\ Recommendation & 40\% & 65\% & 15\% \\ \hline \hline \end{tabular} \(\
eg\)5\(\%\): those who have complaints/participants (20 people) \(\times\) 100.  
\end{table} 
Table 10: Qualitative evaluation of each WAD. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Item** & **N (\%)** & **Ranking** \\ \hline Dimension & 4 (6.67) & 7 \\ Weight & 0 (0.00) & 8 \\ Safety & 5 (8.33) & 6 \\ Durability & 0 (0.00) & 8 \\ Easy to use & 10 (16.67) & 3 \\ Comfort & 16 (26.67) & 1 \\ Effectiveness & 13 (21.67) & 2 \\ Use again & 6 (10.00) & 4 \\ Recommendation & 6 (10.00) & 4 \\ \hline \hline \end{tabular}  
* N: The number of people who chose each item; ranking; ranks with high importance (%).  
\end{table} 
Table 9: WAD factor importance. extension, FCR, and ECRB involved in wrist bending and stretching. This means that these muscles are constantly activated without being affected by the shape and type of WAD. A previous study reporting on the relationship between writing and muscle activity also found that muscle activity related to wrist movement was stably maintained even as grip method changed [21,22]. Therefore, in order to investigate the correlation between grip method and muscle activity, it is necessary to additionally investigate not only muscles related to wrist movement, but also other upper limb muscles such as the biceps brachii and trapezius [23, 24, 25, 26]. In the mean of finger pressure results, SW had higher results in the thumb and index finger compared with other WADs, while WB showed the highest result in the middle finger. The NDWAD was associated with the lowest finger pressure overall.