Page 537 - IJB-10-3

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

Overall, the minimal impact of inferior trim depth opportunities for standardization and expanded design
on AFO stiffness suggested that alterations in the inferior possibilities, though decision-making becomes more
direction may not be as critical in influencing the overall complex. By bridging the gap between empirical design
mechanical response of AFOs. Clinicians may find and technological advancements, the findings of this
reassurance in maintaining flexibility in choosing inferior study can offer insights into the development and
trim depths within a certain range without significantly customization of 3D-printed AFOs for individuals with
compromising stiffness. On the other hand, the notable specific conditions.
changes observed in DF and PF stiffness with variations
in posterior trim depth highlight the importance of this Acknowledgments
parameter in determining the overall rigidity of AFOs. The This research was supported by The Lorenzo and Pamela
substantial decrease in stress concentration around the
ankle region with higher posterior trim depth suggested Galli Medical Research Trust. The authors would like to
a potential enhancement in the overall comfort of AFOs. thank Prof. Kerr Graham for reviewing and editing the
This reduction in stress concentration could be particularly manuscript.
beneficial in mitigating discomfort or pressure points
around the ankle, enhancing its wearability, and minimizing Funding
the risk of adverse effects on the skin and soft tissues. None.
Meanwhile, the reduction of stress concentrations may also
be beneficial to prevent potential fatigue failure of AFOs. Conflict of interest

4. Conclusion The authors declare no conflicts of interest.

The present study was designed to investigate the impact Author contributions
of base materials, thickness, and trimline variations
on the stiffness and deformation of 3D-printed AFOs Conceptualization: Chenxi Peng, Phuong Tran, Erich Rutz
through a comprehensive parametric study based on Formal analysis: Chenxi Peng
numerical modeling. Firstly, the anatomical geometry Investigation: Chenxi Peng, Phuong Tran, Simon Lalor
of the foot and leg was established using a 3D-scanning Methodology: Chenxi Peng, Erich Rutz
system and reconstructed into a smooth surface Supervision: Erich Rutz
representation. Subsequently, a baseline AFO design Writing – original draft: Chenxi Peng
was created, 3D printed, and subjected to testing under Writing – review & editing: Phuong Tran, Simon Lalor,
uniaxial compression. An FE model was developed Oren Tirosh, Erich Rutz
and validated using experimental data. The mechanical
properties of PCTG, PA12, PA12-CF, and PLA were Ethics approval and consent to participate
characterized through tensile tests. A parametric study Not applicable.
on the effects of base materials, thickness, and trimline
location was conducted. Consent for publication
The results indicated that AFOs responded differently to Not applicable.
PF and DF stress, displaying a linear moment–ankle angle
relationship in PF and a nonlinear response in DF with Availability of data
stress concentration around the ankle region. Increasing
AFO thickness enhanced stiffness during both loading The data that support the findings of this study are available
conditions with minimal impact on stress distribution, from the corresponding author upon reasonable request.
while the AFO stiffness–thickness relationship can
be described by a power function. Trimline locations References
influenced AFO stiffness, with limited effect from inferior 1. Graham HK, Rosenbaum P, Paneth N, et al. Cerebral palsy.
trim depth but linear reductions in stiffness with further Nat Rev Dis Primers. 2016;2:15082.
posterior trimming. Larger trim depths reduced stress doi: 10.1038/nrdp.2015.82
concentration around the ankle, potentially leading to
better fatigue resistance. 2. Ma N, Gould D, Camathias C, Graham K, Rutz E. Single-
event multi-level surgery in cerebral palsy: a bibliometric
Currently, AFO design relies heavily on observational analysis. Medicina. 2023;59(11).
assessments and clinical experience. 3D printing offers doi: 10.3390/medicina59111922

Volume 10 Issue 3 (2024) 529 doi: 10.36922/ijb.3390