Beam Makes Bone Implant Biodegrade
AACHEN, Germany, June 9, 2010 — Scientists at the Fraunhofer Institute for Laser Technology (Fraunhofer ILT) are using a razor-thin laser beam to melt a porous bone replacement implant — a process that makes it degradable and stimulates bone regrowth.
This new degradable implant is custom-fit and disappears to the same extent that the bone regrows, unlike titanium, which merely plugs the damaged area.
A degradable implant manufactured at the Fraunhofer Institute for Laser Technology closes the fissures in the cranial region. It was designed by Karl Leibinger Medizintechnik Co. (Copyright: Fraunhofer ILT©)
In contrast to long-term solutions based on titanium, degradable implants are intended to replace the missing pieces of bone only until the fissure closes itself up. That may last months or even years, depending on the size of the defect and the age and health status of the patient.
The new implant improves the conditions for the healing process. It emerged from the ‘Resobone’ project of the federal ministry for education and research and is sized to fit for each patient. Unlike the conventional bony substitutes to date, it is not made up as a solid mass, but is porous instead. Precise little channels permeate the implant at intervals of just a few hundred micrometers.
“Its precision fit and perfect porous structure, combined with the new biomaterial, promise a total bone reconstruction that was hitherto impossible to achieve,” said Dr. Ralf Smeets of the University Medical Center of Aachen.
The porous canals create a lattice structure that the adjacent bones can grow into. Its basic structure consists of the synthetic polylactide or PLA for short. The stored granules from tricalcium phosphate (TCP) ensure rigidity and stimulate the bone‘s natural healing process. As pastes, granulates and semi-finished products, TCP and PLA already have proved to be degradable implants. The body can catabolize both substances as rapidly as the natural bones can regrow. But the material can be applied only in places where it will not be subject to severe stress; therefore, the Resobone implants will primarily replace missing facial, maxillary and cranial bones. Currently, fissures of up to 25 square centimeters in size are able to be closed.
The patient’s computed tomography serves as the template for the precision-fit production of the implants. The work processes – from CT imaging to construction of the implant, through to its completion – are coordinated in such precise sequences that the replacement for a defective zygomatic bone can be produced in just a few hours, while a five-centimeter section of cranium can be done overnight. In addition to the obvious benefits, there is a considerable gain in time during surgery.
“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,” explained Simon Höges, project manager at ILT.
What’s more, the operations are now fewer in number because physicians no longer take the bone replacement from the patient’s own pelvic bone. Similarly, they can dispense with the countless follow-up operations on children to exchange long-term implants that don’t grow as the child matures.
“We have achieved our project goal – a closed process chain to produce individual bony implants from degradable materials,” said Höges, adding that now it is up to the project partners, which also include implant manufacturers, to turn the results into products.
For more information, visit: http://www.ilt.fraunhofer.de/eng
- Technique that defocuses activity from surrounding planes by means of the relative motions at the point of interest.
MORE FROM PHOTONICS MEDIA