A modified hot glue gun can mend broken bones

With slight modifications, hot glue guns commonly used in arts and crafts can repair damaged bones quickly and cheaply, researchers say.

Bones can repair themselves after small injuries, but if there is a void – because of serious trauma or tumour removal, for example – then that space needs to be filled with either a graft or an artificial plug made of a material that encourages bone cells to spread.

One solution is to use 3D printers to create perfectly-fitting scaffolds to fill such voids, but this requires scanning and remote fabrication – a process taking at least a week. That is fine for a pre-planned operation to fix a worn-out joint, for example, but not for emergency trauma surgery.

To solve this problem, Jung Seung Lee at Sungkyunkwan University in South Korea and his colleagues have developed a system that can be applied instantly during a single surgery.

They modified a hot glue gun by reducing the temperature at which it operates from over 100°C to around 60°C. They also concocted a material that acts as a biological glue – a mixture of hydroxyapatite, which makes up 50 per cent of the volume of normal human bones, and a biodegradable thermoplastic called polycaprolactone.

Surgeons can use the hot glue gun to fill bone voids in a matter of minutes during surgery and bone cells are then able to span the gap and permanently repair the injury over time.

“It is basically made of commercially available hot glue guns,” says Lee. “We can save time and cost.”

Lee and his colleagues tested the glue gun by repairing centimetre-long gaps in rabbits’ femur bones. In samples taken after 12 weeks, there were no signs of medical problems or separation between the glue and the bone.  The bone volume was more than twice as high in the animals treated with the glue gun than in control animals where the repair was made with traditional bone cement.

The researchers also found they could incorporate vancomycin and gentamicin, two antibacterial compounds, into the filament to reduce the potential for infection. The drugs are released slowly and diffuse directly onto the surgical site over several weeks.

Benjamin Ollivere at the University of Nottingham, UK, who is researching 3D-printed scaffolds for bone repair, is sceptical a hot glue gun will end up becoming a widely-used solution ahead of faster scanning and 3D-printing technology.

“Do I think it’s an interesting concept? Yes. Could it feasibly work?
 Yes. Do I think it’s within the range of the plausible? 
Yes,” he says. “But this might not be the thing.”