Knee damage is an all too common and painful sports injury, often requiring surgery. Routinely, surgeons will replace a torn ligament with a piece of tendon from the leg and fix the new tendon with a steel or titanium screw. A second surgery is then required to remove the screw.
Researchers from the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research (IFAM) in Bremen, Germany, have developed a biodegradable screw, making the second surgery and the use of a titanium screw unnecessary.
Currently, surgeons use a form of biodegradable screws but these often leave holes in the bone once they have degraded. The researchers at IFAM have devised a superior version, using a moldable composite comprising of a ceramic which is the main component in bone material. These screws actually encourage bone growth into the implant.
Engineers at IFAM developed a granulate that can be processed using the regular injection molding method. These biodegradable screws do not require any further processing, like milling.
Another positive effect of these screws is that energy is saved in the process of making them. The screws can be compressed at just 284 degrees Fahrenheit, where the current process requires a temperature of 25,232 degrees Fahrenheit.
The biodegradable screws are so close to the property of real bone and can withstand more than 130 neutrons per square millimeter. Our real bones can withstand between 130 and 180 which makes them extremely compatible.
“We have modified bio-materials in such a way that they can be formed into robust bioactive and resorbable screws by means of a special injection molding process,” explained Dr. Philipp Imgrund, head of the biomaterial technology department at IFAM. “This composite possesses a higher property of hydroxylapatite and promotes the growth of the bone into the implant."
The biodegradable screws developed by IFAM typically take 24 months to degrade.
The scientists at IFAM hope to develop more implants in the future, using the same energy-saving process.