# Clinical Assessment of Customized 3D-Printed Wrist Orthoses
## 2 Materials and Methods
### Determine Proper Time of Plaster Cast Curing for Pressure Measurement in Phase I  
3M\({}^{\text{TM}}\) Scotchcast\({}^{\text{TM}}\) Plus Casting Tape (4\({}^{\prime\prime}\times 4\) yds, 3M\({}^{\text{TM}}\) Health Care, USA) was used in this experiment. After the fiberglass casts were set, stress relaxation and creep are likely to occur during curing. This could have affected the pressure measurements of the forearm, wrist, and palm over a period of time. Therefore, this experiment aimed to determine the length of time required to obtain stable pressure readings. After the plaster was applied, pressure measurements were taken at 10, 30, 60, 90, 120, and 180 min, in four postures.  
Six participants were recruited for this experiment, and there were more than two measurement time points, so the generalized estimating equation (GEE) was used for statistical analyses. As shown in Table 1, a \(p\)-value less than 0.05 indicated that a significant difference in pressure had occurred. The average pressure was considered a reactive variable. The significant variables were the time point, sensor location, and posture.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multicolumn{8}{c}{**Baseline**} \\ \cline{2-9}  & **10 Min** & **30 Min** & **60 Min** & **90 Min** & **120 Min** & **150 Min** & **180 Min** \\ \hline Intercept & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * \\ \hline
10-min &. & 0.1277 & 0.012 * & 0.0093 * & 0.0727 & 0.0027 * & 0.0083 * \\
30-min & 0.1277 &. & 0.2032 & 0.1422 & 0.5734 & 0.089 & 0.0937 \\
60-min & 0.012 * & 0.2032 &. & 0.2661 & 0.8296 & 0.2214 & 0.1345 \\
90-min & 0.0093 * & 0.1422 & 0.2661 &. & 0.4333 & 0.6635 & 0.4348 \\
120-min & 0.0727 & 0.5734 & 0.8296 & 0.4333 &. & 0.3681 & 0.0066 * \\
150-min & 0.0027 * & 0.089 & 0.2214 & 0.6635 & 0.3681 &. & 0.3022 \\
180-min & 0.0083 * & 0.0937 & 0.1345 & 0.4348 & 0.0066 * & 0.3022 &. \\ \hline ROI1 & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * \\ ROI2 & 0.0317 * & 0.0317 * & 0.0317 * & 0.0317 * & 0.0317 * & 0.0317 * & 0.0317 * & 0.0317 * \\ ROI3 & 0.0149 * & 0.0149 * & 0.0149 * & 0.0149 * & 0.0149 * & 0.0149 * & 0.0149 * & 0.0149 * \\ ROI4 & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * \\ ROI5 & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * \\ ROI6 &. &. &. &. &. &. &. \\ \hline Arm Sling & 0.0131 * & 0.0131 * & 0.0131 * & 0.0131 * & 0.0131 * & 0.0131 * & 0.0131 * & 0.0131 * \\ Extension & 0.0003 * & 0.0003 * & 0.0003 * & 0.0003 * & 0.0003 * & 0.0003 * & 0.0003 * & 0.0003 * \\ Flexion & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * & \textless{}0.0001 * \\ Neutral &. &. &. &. &. &. &. \\ Position &. &. &. &. &. &. &. \\ \hline \hline \end{tabular}
\end{table}
Table 1: GEE estimation.  
Figure 3: Clearance adjustment region of the wrist brace.  
For the arm sling posture, the only significant difference was observed at the 10 min time point (_p_ < 0.05). In the neutral position, a significant difference was observed between the 10 min time point and those after the 90 min time point (_p_-value < 0.05); the 30 min time point also showed a significant difference (_p_-value < 0.05) to the 90 min, 150 min, and 180 min time points. The 90 min time point showed no significant difference to the 120 min, 150 min, and 180 min time points. Therefore, the 90 min measurement window established in this experiment was confirmed.