# Clinical Assessment of Customized 3D-Printed Wrist Orthoses
## 4 Discussion  
In this study, the basis for determining the immobilization capability was the pressure exerted by the cast and brace on the skin. A previous study showed that the pressure exerted on the skin can be used as a guide to prevent complications [4]. However, due to differences in individuals and the regions of injury, there is no universal basis to determine the occurrence of complications. In this study, several pressure measurements exceeded 40 mmHg, but there was no reported discomfort from the participants. The reason may be that the participants had only worn the brace for 4 to 5 h, which may be insufficient time for any major discomfort to emerge. If the clearance of the customized wrist brace at ROIs 3 and 6 was decreased to 0.3 mm, the pressure readings at ROIs 2 and 5 exceeded those from the plaster cast, and the participants reported tightness around the wrist. This was resolved during the clinical trials, with confirmation from the physicians, by loosening the clearance around the wrist from 2 mm to 3 mm. The participants recruited in this study for Phase I were 20 to 30 years of age, healthy, and without a previous history of wrist injuries. The average age of the patients in clinical trial was significantly older than the Phase I participants. Therefore, impressions of the exerted pressure may have been different due to age differences. In addition, a typical patient usually wears a brace for weeks, and the conditions presented in daily life can be quite different from those that occurred during the experiment. Start time when wearing 3D-printed brace was always an issue. The 3D-printed brace was usually applied to patients 10 days after surgery when swelling reduce. It then took about 2 to 3 days to scan, design, and manufacture. Under these circumstances, the fiberglass cast was inevitably used for temporary protection and immobility until the personal cast was ready. Based on the mirror image of contralateral (non-fractured) wrist for well-tolerated brace design, [PERSON] et al. applied a three-pad brace on the first day of post-traumatic swelling [20]. However, a high rate of secondary fracture displacement led to early discontinuation of the study and a very small sample size. [PERSON] et al. proposed an automatic design and manufacture schema to fulfill the strength and possible economic criteria. Therefore, an orthosis on the second day after scanning can be delivered to patients [11]. In order to judge the representativeness of the Phase II clinical survey results, we listed the most related reference DASH outcomes and compared them with our results in Table 8. The reference undisplaced/cast data were compared with our non-operative/cast data (N = 9). The primary operation data were compared with customized brace data (N = 24). The 3 month data at values of 37.41 (non-operative/plastic cast) and 24.16 (operative/customized brace) were compared with the reference data at values of 23 (undisplaced/plastic cast) and 22 (operative), respectively. The value sets and clinical survey results for the current study and the reference study were comparable, and they demonstrated the same fracture-healing trend. Customized braces also demonstrated superiority over plaster casts over long wearing periods. In the reference DASH data, the customized brace scored extremely low (0.52 versus reference data 16) after a one-year period. This suggests that the disability level of customized braces have nearly no effect on patients' daily lives. Since the technology appears versatile and its cost may decrease in the near future, the identification of further potential applications in orthopedics as an alternative choice of current available plaster casts is of interest. Functional outcomes were evaluated by DASH and MAM in a one-year follow up in Phase II trial. It shows the 3D-printed orthoses have better daily activity than the fiberglass cast. Table 9 shows a comparison table of design method for 3D-printed wrist orthoses.