A tool made from a modified glue gun can now repair broken bones in surgery by 3D-printing grafts directly onto them.
Bone implants have historically been made of metal, donor bone and more recently 3D-printed material.
But in cases involving irregular bone breaks, these implants need to be designed and produced prior to surgery to allow for appropriate fitting, the researchers explain.
The new tool—which has been tested on rabbits—was developed to quickly create complex bone implants without the need for any manufacturing in advance.
The team also optimized the 3D-printed bone grafts for high structural flexibility, the release of anti-inflammatory antibiotics and the promotion of natural bone regrowth at the grafting site.
“Our proposed technology offers a distinct approach by developing an in situ printing system that enables a real-time fabrication and application of a scaffold directly at the surgical site,” study author and biomedical engineer Jung Seung Lee of biomedical Sungkyunkwan University, South Korea, said in a statement.
“This allows for highly accurate anatomical matching even in irregular or complex defects without the need for preoperative preparation such as imaging, modeling and trimming processes.”
The material fed into the glue gun is a filament made of two major components: a component of natural bone, known to promote healing, called hydroxyapatite (HA) and a biocompatible thermoplastic called polycaprolactone (PCL).
PCL can liquify at temperatures as low as 140 degrees Fahrenheit, which—when applied with a heat-modified glue gun—is cool enough to prevent tissue damage during surgical application, while also being able to conform to the jagged grooves of fractured bone, according to the team.
By adjusting the proportion of HA to PCL within the filament, the researchers can customize the hardness and strength of the grafts to fit different needs in the body.
“Because the device is compact and manually operated, the surgeon can adjust the printing direction, angle and depth during the procedure in real time,” Lee explained.
“Also, we demonstrated that this process could be completed in a matter of minutes. This highlights a significant advantage in terms of reducing operative time and improving procedural efficiency under real surgical conditions.”
As infection is a common concern with surgical implants, the researchers incorporated vancomycin and gentamicin, two anti-bacterial compounds, into the filament.
In both solid petri dish culture and liquid solutions, the filament scaffold successfully prevented the growth of E. coli and S. aureus, two common bacteria prone to cause infection post-surgery.
The physical properties of HA and PCL in the filament allow the drugs to be released slowly and diffuse directly onto the surgical site over several weeks.
“This localized delivery approach offers meaningful clinical advantages over systemic antibiotic administration by potentially reducing side effects and limiting the development of antibiotic resistance, while still effectively protecting against postoperative infection,” said Lee.
As a proof of concept, the device was tested on severe femoral bone fractures in rabbits. Within 12 weeks after surgery, the team found no signs of infection or injury of body tissue and greater bone regeneration outcomes when compared to rabbits grafted with bone cement—commonly used for treating bone defects.
“The scaffold was designed not only to integrate biologically with surrounding bone tissue but also to gradually degrade over time and be replaced by newly formed bone,” Lee explained.
“The results showed that the printing group exhibited superior outcomes in key structural parameters such as bone surface area, cortical thickness and polar moment of inertia, suggesting more effective bone healing and integration.”
The researchers are planning to optimize the anti-bacterial potential of the scaffold even further and prepare the procedure for human trials.
“Clinical adoption will require standardized manufacturing processes, validated sterilization protocols and preclinical studies in large animal models to meet regulatory approval standards,” said Lee.
“If these steps are successfully achieved, we envision this approach becoming a practical and immediate solution for bone repair directly in the operating room.”
Newsweek has reached out to the researchers for additional comment.
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Reference
Jeon, I. Y., Jeon, Y. M., Choi, J. H., Lee, S., Kim, M., Kim, J. H., Lee, J. S., Hwang, J., Jeong, D., Carroll, G. A., Wentworth, A., Yang, K., Park, S., Raskin, K. A., Jang, W. Y., Traverso, G., & Lee, J. S. (2025). In situ printing of biodegradable implant for healing critical-sized bone defect. Device, 3. https://doi.org/10.1016/j.device.2025.100873
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