Page 427 - IJB-9-3

International Journal of Bioprinting 3DP PILF cage for osteoporotic

Figure 9. Status of contact areas between cage and endplate for CS-type and P-type cages under all load condition simulations. Red ovals/circles indicate
the positions of fractures or damages. Bottom left: two red oval regions show the possibility superior/inferior contact areas of the CS-type cage; bottom
right: four red circle regions show the possibility of superior/inferior contact points of the P-type cage.

for the mechanical assessment of spinal intervertebral 5. Conclusion
body fusion devices (IBFDs) used in spinal arthrodesis
procedures. Table 3 presents optional acceptance criteria This study integrated WTO and FE analysis to design a
for yielding load and stiffness for all loads derived from posterior lumbar interbody fusion cage with appropriate
aggregated mechanical test data from IBFDs previously structural strength and anatomically curved surface for
cleared by the U.S. FDA through the 510(k) process. The stress transfer and internal lattice design for bone ingrowth
values in Table 3 represent the 5 percentile of the range based on the osteoporotic endplate morphology. The FE
th
of devices surveyed. This document was also encouraged analysis result showed that the maximum endplate stress
to incorporate a safety factor to define acceptance criteria. values under all daily activities for the plate P-type cage
We found that the safety factors in our cage were relatively with point contact implantation model were all higher
small under torsion conditions, and the largest under than those for the anatomically CS-type cage with surface
compression conditions. The fracture pattern of our contact. The newly designed osteoporotic anatomical cage
newly designed cage with applied loads reached ultimate needed to be manufactured using 3D printing technique.
strength. No damage was visually found under the static The in vitro biomechanical functional test confirmed that
compressive test. The pillar in the middle of the cage the designed cage met 95% of the standard requirements
was obliquely fractured due to the shear force under the for ISO 23089 standard listing.
compressive-shear test. Minor wear was found on the Acknowledgment
corners, possibly caused by friction between the cage and
the fixture under torsion (Figure 8). Not applicable.

Volume 9 Issue 3 (2023) 419 https://doi.org/10.18063/ijb.697