Page 534 - IJB-10-3

International Journal of Bioprinting Mechanical responses of 3D-printed AFO

Figure 7. Effect of ankle-foot orthosis (AFO) thickness. (a) AFO moment–ankle angle relationships of baseline AFO with various thicknesses under
plantarflexion and dorsiflexion. (b) The stiffness of baseline AFO with various thicknesses. Deformation and stress contours of the baseline with various
thicknesses at 10° rotation: (c) dorsiflexion and (d) plantarflexion.

Figure 8a compares moment–ankle angle relationships increasing the trim depth in the inferior direction may
for AFOs with inferior trim depths ranging from 10 to 25 contribute to a more even stress distribution across the
mm. The changes in trimline depth in the inferior direction AFO, potentially mitigating stress concentrations around
had limited effects on the DF and PF behaviors of AFOs. A the ankle region and preventing potential fatigue damage.
linear moment–ankle angle relationship was found for all
AFOs under plantarflexion. By comparison, the moment Figure 9a compares moment–ankle angle relationships
increased linearly with an increase in ankle angle and was for AFOs with posterior trim depths ranging from 10 to
followed by a diminishing phase under DF motions. Figure 25 mm. The increase in trim depth along the posterior
8b displays the DF and PF stiffness of AFOs with different direction reduced the moment required at the same DF
inferior trim depths. With a further trim of AFO along or PF angles and also affected the mechanical responses.
the inferior direction from 10 to 25 mm, the decreases in A linear moment–ankle angle relationship was found for
both DF and PF stiffness were less than 10%. The impact of AFOs with small posterior trim depth under PF, while DF
varying inferior trim depth on the overall stiffness of AFOs response displayed nonlinearity. However, with further
was modest. Figure 8c and d presents the deformation and trimming of the AFO along the posterior direction, the DF
stress contour of AFOs. The overall stress distribution of the AFO resulted in a linear response only. Meanwhile,
remained consistent for all AFOs, with a notable reduction a higher moment was required to deform the AFO to the
in stress around the ankle region for AFOs with higher same DF and PF angle with an increase in posterior trim
trim depth along the inferior direction. This suggests that depth. Figure 9b compares the stiffness of different AFOs

Volume 10 Issue 3 (2024) 526 doi: 10.36922/ijb.3390