After testing several options, the team discovered the ideal materials for their innovative healing bullets. They settled on a biocompatible thermoplastic called polycaprolactone, combined with hydroxyapatite. Polycaprolactone is FDA-approved and breaks down in the body within months. Hydroxyapatite promotes bone tissue growth. Lee and his team carefully adjusted the mix until they found the perfect balance: it extruded at a safe 60°C, was structurally strong, bonded well with bone, and could degrade over time.
The team then tested these healing bullets on rabbits with broken femurs. The results were promising—those treated with the healing gun healed faster than those using conventional bone cement. However, there’s still a long road ahead before this technology can be applied to humans.
One issue that emerged was the slow degradation of the implants, which limited the full restoration of bone tissue. To tackle this, Lee plans to integrate antibiotics into the mix, allowing the implants to release medication gradually to ward off infections.
Another challenge is ensuring that the healing gun can handle the loads it will face in human patients. While rabbits are useful as test subjects, their weight is considerably less than that of humans. “We need to test this technology in larger animal models to assess its long-term safety,” Lee pointed out.
Additionally, the skill needed to operate this healing gun poses a concern. Traditional 3D printers use guiding systems for accuracy, which may not be as reliable in a handheld device. Lee acknowledged, “It’s true that the system requires practice. We might need to add a guiding mechanism for better precision.” This could pave the way for the next generation of bone printing devices.
In a related study, researchers found that advancements in 3D printing for medical applications could enhance recovery times significantly—by up to 30% in some cases—when compared to conventional treatments. As technology evolves, it’s clear that approaches like Lee’s healing gun could reshape how we treat bone injuries.
For more details on this cutting-edge research, you can view the complete study here: DOI: 10.1016/j.device.2025.100873.
