Researchers at Fraunhofer’s Institute for Laser Technology say they are getting excellent results from a bone replacement system that uses a paste of polyactide (PLA) and tricalcium phosphate that is melted by a fine laser to build up layers of material that can provide a strong and precise fit.
This new approach was developed under the aegis of federal ministry “Resobone” project in Germany.
Researchers say the laser-treated paste develops precise microchannels in the PLA, creating a lattice structure which the adjacent bones can grow into. “Its precision fit and perfect porous structure, combined with the new biomaterial, promise a total bone reconstruction that was hitherto impossible to achieve,” says Ralf Smeets of the University Medical Center of Aachen.
Both PLA and TCP are tolerated well by the body. Many consumers have unknowingly run into PLA, the major component of biodegradable packaging material and clear disposable cups that are becoming commonplace. While the PLA provides the framework, the TCP resides in more or less a granular form in it and acts as a stimulus for bone growth. The body can catabolize both substances as natural bone grows through the lattice.
Fraunhofer says the PLA/TCP Resobone system isn’t really suitable for bones that experience high stress, such as in limbs or joints. Instead, it is ideal for certain low-stress bony areas such as cranial, facial and maxillary bones. For example, a five-centimeter large replacement piece of cranium can be completed in an overnight process that uses data from CT imaging to guide a thin laser beam to melt the PLA/TCP mix layer by layer. The precise, customize-sized implants that results from this “Selective Laser Melting” process can be as thin as 80 micrometers and as large as 25 square centimeters.
Fraunhofer gives much of the credit for developing the manufacturing process to its Institute for Laser Technology in Aachen.
“No custom-fit, degradable implants ever existed before now. During the operation, the surgeon had to cut TCP cubes, or the patient‘s own previously removed bone material, to size and insert it into the fissure,” explains Simon Höges, project manager at ILT. “We have achieved our project goal: a closed process chain to produce individual bony implants from degradable materials.