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Zolfagharian, et al.
During the early years of the introduction of the splints can also be made to accommodate extremes
FDM technique, it was used to print prototypes, of size or deformities that off the shelf splints cannot.
souvenirs, and other useful domestic appliances [21,22] . Utilizing this technology means that a patient can
However, FDM technology is rapidly maturing and receive the same quality of care regardless of the
is reportedly showing unlimited potential in various health professionals level of skill and experience
applications, including in the medical, automotive, in splint manufacturing immediately after an injury
and aeronautical fields [23-25] . FDM can benefit the the patient gets their finger scanned and a medical
mallet finger treatment through making complex professional selects the template for their finger
shapes that could not be made by traditional injury that is then automatically updated with the
manufacturing methods as well as its ability to utilize exact dimensions of their finger. A personalized
alternative materials with improved performance finger splint is then printed off, tailored to them
characteristics [7,26] . exactly, to allow for the chance at the most optimal
The first step of FDM printing is to develop a recovery followed by ongoing rehabilitation with a
computer-aided drawing (CAD) of the component. health professional.
That CAD file is then exported as a stereolithography The personalized FDM 3D-printed
(STL) file. This STL file is then “sliced” by the thermoplastic finger splint in this study could
3D printer’s software and read by the printer to potentially address all those common causes of
print the component in a series of layers . FDM treatment failure, such as skin irritation, poor
[27]
prints thin layers of plastic layer by layer to create splint fit and discomfort wearing the splint, which
the part. Plastic is fed into the extrusion head and would lead to less treatment failure and therefore
then heated so that it enters a semi-liquid state; more successful recovery cases.
the plastic is then pushed out of a small nozzle to
produce a fine thread of plastic that it layers onto 2 Methodology
the previous layer or onto the base support piece.
Because of this layer on the layer structure of the The goal of this study is to utilize the FDM method
material, the mechanical properties and surface to develop a patient-specific 3D-printed finger splint
finish of an FDM printed part are dependent on that could potentially have the properties required to
the orientation of which it is printed. This means match and exceed those of the current hand-molded
even the same part can have different mechanical thermoplastic splints. The original splint will be
properties if printed in different orientations . compared with the topology-optimized splints in
[28]
Despite previous studies into AM for use in terms of structural and thermal performance. With
lower limb prosthetics and orthotics, the use of these processes, splints can be produced with much
3D printing technologies for the use on the upper better mechanical properties requiring less material
extremities of the arm, including wrist, hand, and for more breathability and comfort while having the
fingers, has yet to be investigated broadly . Up same strength. The detailed steps of achieving this
[11]
to the present time, there has been limited research aim are outlined in the following.
in the area of upper extremity splinting with 2.1 Measurements of finger and personalized
engineering design and analysis motivation [5,29] . CAD splint
The interest in 3D printing in this area is due to
multiple reasons. One is the scalability with respect The patient-specific splint was designed by
to the range of sizes. It is completely customizable measuring seven parameters of a patient’s index
to the patient’s injury. In addition, multiple splints finger, as shown in Figure 3. To measure the
can be printed for the patient over the course of maximum force that could be applied by the index
their recovery as swelling reduces to ensure the finger, the intermediate and proximal joints of
splint is optimally fitted at all times throughout their the finger were locked in position using medical
recovery . This practice potentially provides the tape to the bottom of the finger. This left the
[30]
best outcome for the patient. Further, 3D printed distal interphalangeal joint of the finger, the joint

International Journal of Bioprinting (2020)–Volume 6, Issue 2 19