Scientists are one step closer to building artificial bone that truly behaves like the real thing.
Researchers at the University of New South Wales have developed 3D printed scaffolds that mirror the strength and porosity of natural bone. By fine-tuning the internal structure, the team showed the scaffolds can take an impact, let fluids flow through them, and even offer support for healing.
“We found three important results,” Dr. Juan Pablo Escobedo-Diaz, one of the authors of the study, said in an email. “First, the scaffolds were much stronger under sudden impact. Second, the way the scaffolds fractured changed depending on the grading direction. Third, the flow of fluids through the scaffolds was similar to that in real bone.”
Why artificial bone is so difficult to make
Replacing or repairing damaged bones is a major challenge in medicine. Surgeons often use metal implants or grafts from other bones, but these options have drawbacks: metals can be too stiff and may cause stress on surrounding tissue, while grafts are limited in supply.
3D printing has raised hopes for patient-specific bone replacements. But building an artificial scaffold that really works inside the body is not simple.
“Real bones have a complex structure,” Escobedo-Diaz explains. “It is light, porous like a sponge, and still very strong. Its irregular, sponge-like shape makes it hard to print without collapsing. Many early scaffolds failed to reproduce this structure accurately.”
If the structure is too dense, cells can not grow inside. If it is too porous, it breaks too easily. Getting designs that balance strength and porosity — and ensuring they can pass medical approvals — has been one of the biggest hurdles for researchers.
Learning from nature
To overcome the challenge, the researchers turned to nature for inspiration. Real bone is not the same throughout: it gradually shifts from compact, dense regions to lighter, sponge-like areas. The team mimicked this gradual change by designing scaffolds with smoothly varying density, known as graded structures.
“We used a design approach inspired by natural bone. In bone, the structure changes gradually from dense areas to more open areas. We recreated this idea by printing scaffolds with graded structures in different directions,” says Escobedo-Diaz.
The material of choice was polylactic acid, or PLA, a biodegradable plastic already well studied for medical use. The researchers kept the porosity at around 55 percent, a balance that made the scaffolds strong yet still open enough for fluids and cells to pass through.
What the tests revealed
The team subjected the printed scaffolds to a series of mechanical tests. One striking finding was that the scaffolds performed better under sudden impacts than under slow, steady pressure. “They showed about 60 percent higher strength and 16 percent higher stiffness compared with slow loading,” says Escobedo-Diaz. That resilience could make them well suited to protect against accidents or stresses in everyday life once implanted.
Another key observation was that the way the scaffolds fractured depended on the direction of the grading. This means the orientation of the printed structure can strongly influence performance, giving designers an extra lever to tune the material for different applications.
Equally important, the researchers found that fluids could flow through the scaffolds in ways that closely resemble natural bone. This fluid movement is crucial for healing, delivering nutrients, and removing waste.
Despite the progress, artificial scaffolds are not yet a full substitute for living bones. “The scaffolds are strong and porous, but they cannot heal or grow like real bone. Natural bone adapts to the loads it carries, while artificial scaffolds stay fixed. They also do not yet encourage blood vessel growth without extra help,” Escobedo-Diaz points out. For now, the scaffolds provide structural support but cannot replicate bone’s ability to remodel and self-repair.
Even with these limits, the potential is significant. Escobedo-Diaz sees a realistic timeline for clinical use: “We expect to see these scaffolds used in practice in about 5 to 10 years. More testing, safety approvals, and hospital production will be needed first. In the short term, they can be used in research and patient-specific modeling. In the future, they may help repair large defects in bones like the femur.”
Such scaffolds could eventually replace or supplement metal implants in cases where large sections of bone are missing due to injury, disease, or surgery.
Future directions
The team is already thinking about the next steps. “We plan to improve the designs further by using biomimetic approaches, meaning we will take inspiration from how natural bone and other biological structures are built. This includes creating more complex patterns and gradings that copy nature’s way of combining strength with lightness,” says Escobedo-Diaz.
They also intend to test the scaffolds under more demanding conditions, such as repeated impacts and long-term use inside the body. The ultimate goal is to create implants that are not only strong and safe but also capable of supporting natural healing more effectively.
Featured image credit: IAOM-US via Pixabay
