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Waldburger, et al.

Figure 4. 3D-printed metacarpal brace for a metacarpal fracture.
trial. Statistical analysis included descriptive statistics for detailed numbers). One patient in the 3D group
and calculation of P-values with the Mann–Whitney U reported strong pain while wearing the splint; however,
test. Data for dropouts were not included. she could not differentiate whether the pain was caused
by her fibromyalgia or the splint.
3. Results In two patients of the 3D group, partial breakage of
Within a 6-month period in 10/2019 and 04/2020, 24 a 3D splint (Figure 5) occurred after 26 days and 37 days
of 32 screened patients were enrolled in this trial (10 in of wearing time, which did not lead to any treatment
control group and 14 in 3D group). Eight patients did complications. A third 3D splint showed fine fissures
not match the inclusion criteria. Four patients had to be at the 2-week follow-up, which could be closed by the
excluded during follow-up and were replaced, including occupational therapist after heating the splint with hot air.
a patient from the 3D group who needed a change of Adjustment rates were similar for 3D and
splint design; for organizational reasons, the occupational thermoplastic splints, with a mean (standard deviation) of
therapist made the new splint from thermoplastic material. 1.44 (1.24) adjustments for 3D splints and of 1.0 (1.15)
Another patient was excluded because of communication adjustment for thermoplastic splints over the whole
obstacles that became apparent only during the response course of follow-up. Occupational therapists’ overall
to questionnaires. reported satisfaction with splints was good or very good
Two patients went on vacation, which led to in all cases, except in the cases of splint breakage.
wearing incompliance in a patient and missing data We observed a huge variation in production time,
for the other. The remaining 20 patients completed as shown in Table 4. The mean duration of the first
all three questionnaires. Of these, two patients had occupational therapy consultation was similar in the
a missing second assessment from the occupational control group (39.5 min) to that in the 3D group (30.5 min).
therapist because they did not present to the respective However, while thermoplastic splints were entirely
consultation but assured the study team by phone fabricated within that time, the complete production
that everything was fine. One patient missed the third process of 3D splints took a mean of 179.5 min, excluding
assessment because he did not bring the splint to the printing time.
occupational therapy visit. Patient characteristics are 4. Discussion
summarized in Table 2.
The mean wearing time of the definitive splint was The aim of this trial was to evaluate the feasibility of the
35.1 days until the end of follow-up (32.9 days in the 3D use of 3D-printed made-to-measure splints in a clinical
group and 37.3 days in the control group). Analysis of hand surgical setting and to compare them to standard
the questionnaires did not reveal any clear differences custom-made thermoplastic splints by an occupational
between the two groups in terms of patient satisfaction therapist. For this trial, the 3D splint designs were similar
and comfort. In both groups, all patients initially scored to current thermoplastic designs, and the potential benefits
high for splint fit, adjustment process, and satisfaction of the new method were not explored.
with the weight of the splint. Overall satisfaction scores Our results suggest that it is generally feasible to
at the end of their wearing period ranged between 5 and produce different hand splint designs by 3D scanning
10 with only small differences between groups (Table 3 and printing with satisfactory comfort for the patient.

International Journal of Bioprinting (2022)–Volume 8, Issue 1 131