Researchers develop surgical bone screws that biodegrade in two years

Most modern broken bones are healed with the help of titanium screws and plates that sometimes must be removed afterward.

But researchers at the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research in Bremen, Germany have developed a new type of screw that can biodegrade in two years.

Better still, it can encourage bone growth into the implant itself — meaning no screw holes will be left behind.

Biodegradable surgical screws aren’t new. Current models are made of polylactic acid, which leave holes once they degrade.

The IFAM researchers’ screws are made of a moldable composite of polylactic acid and hydroxylapatite, a naturally-occurring mineral that is the main ingredient of actual bone.

“We have modified biomaterials in such a way that they can be formed into robust bioactive and resorbable screws by means of a special injection-molding process,” IFAM biomaterial technology department head Philipp Imgrund said in a statement. “This composite possesses a higher proportion of hydroxylapatite and promotes the growth of bone into the implant.”

The engineers create the screws using a “special injection molding process.” They have also developed a granulate that, using injection molding, can produce a screw, without the need for milling afterward.

The researchers’ screw is physically similar to bone, offering a compressive strength of more than 130 newtons per square millimeter. In comparison, a real bone can handle 130 to 180 newtons per square millimeter.

Finally, production of the screws is easy because the temperature required for compression is just 280 degrees Fahrenheit, far less than the 2,500-degree temperatures required in conventional powder injection molds.