Scientists have designed a new tool that works like a glue gun but prints bone grafts directly onto broken or damaged bones during surgery.
The technology, described in the journal Device, has so far been tested in rabbits and shows promise for creating customized bone implants quickly and safely—without the need for complicated preparation before surgery.
Traditionally, bone implants have been made from metal, donated bone, or prefabricated 3D-printed materials.
While effective, these options require detailed imaging and modeling ahead of time, especially when fractures are irregular.
That means patients often face long waits while implants are prepared, and surgeons must carefully shape and trim the pieces during the procedure to ensure a good fit.
The new device offers a very different approach. By using a heat-modified glue gun, surgeons can print bone-like scaffolds directly into the fracture site in real time.
“This allows for highly accurate anatomical matching even in irregular or complex defects without the need for preoperative preparation,” said Jung Seung Lee, associate professor of biomedical engineering at Sungkyunkwan University and co-author of the study.
The printable material is made from a blend of hydroxyapatite (HA), a natural component of bone that supports healing, and polycaprolactone (PCL), a biocompatible plastic that melts at just 60°C.
This low temperature is cool enough to avoid tissue damage while allowing the material to flow smoothly into jagged bone gaps.
By adjusting the mix of HA and PCL, surgeons can control the strength and flexibility of the graft depending on the bone being repaired.
Because the device is compact and manually operated, surgeons can adjust the direction, angle, and depth of printing on the spot. The process takes only minutes, reducing time in the operating room and improving efficiency.
To address infection risks—one of the biggest challenges with implants—the team added two antibiotics, vancomycin and gentamicin, to the filament. In laboratory tests, the printed scaffolds effectively killed harmful bacteria such as E. coli and Staphylococcus aureus.
The drugs are released slowly over several weeks, delivering protection directly at the surgical site while minimizing side effects and reducing the risk of antibiotic resistance.
When tested on rabbits with severe thigh bone fractures, the printed scaffolds integrated well with natural bone. After 12 weeks, the animals showed no signs of infection or tissue death, and their bone regeneration was stronger compared to animals treated with standard bone cement.
The printed scaffolds gradually degraded over time, being replaced by newly formed bone tissue.
The researchers now aim to refine the antibacterial properties of the material and prepare for human trials.
According to Lee, the next steps include meeting safety standards through large animal testing, sterilization validation, and regulatory approvals.
If successful, this simple glue gun-like device could become a practical solution for repairing broken bones right in the operating room, offering faster healing and fewer complications for patients.
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