A new 3D printing "glue gun" can generate bone grafts directly onto fractures, using a revolutionary process that can fill-in the gaps around the site's jagged edges.

Now, the researchers in South Korea are preparing for human trials, having developed a tool made from a modified glue gun that can 3D-print bone grafts to repair defects during surgery.

Essentially, it quickly creates bone implants on the spot, without the need for making them in advance.

The researchers "optimized" the 3D-printed grafts until they exhibited high structural flexibility while releasing anti-inflammatory antibiotics and promoting natural bone regrowth at the grafting site—conforming to the jagged edges of a fracture.

Bone implants have previously been made of metal or donor bone or, more recently, 3D-printed material. But in cases involving more complex fractures the implants must be designed and produced prior to surgery to allow for appropriate fitting.

So, the scientists developed a new technology that offers a distinct approach: a printing system for use directly at the surgical site, that enables a "real-time fabrication and application of a scaffold," said study co-author Professor Jung Seung Lee, of Sungkyunkwan University in South Korea.

"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."

What's in the 'glue'?

He explained that the material fed into the glue gun is a filament comprised of two major components: a feature of natural bone known to promote healing called hydroxyapatite (HA) and a biocompatible thermoplastic called polycaprolactone (PCL).

PCL can liquify in temperatures as low as 60 Celsius, which when applied with a heat-modified glue gun, is cool enough to prevent tissue damage during surgical application while being able to conform to the jagged grooves of fractured bone.