Fraunhofer: Made to measure bone implants using laser melting

23 Jun 2010 | News

Research lead | Development opportunity

Researchers at the Fraunhofer Institute of Laser Technology in Aachen have devised a method for making made to measure, porous bone implants from degradable materials, which can be produced in advance of surgery.

The development has come out of Resobone, a project funded by the Federal Ministry for Education and Research.

Unlike conventional bony substitutes to date, the material of the new implants is not made up of a solid mass, but is porous, with channels permeating the implant at intervals of just a few hundred micrometers. The porous canals create a lattice structure that the adjacent bones can grow into. “The precision fit and perfect porous structure, combined with the new biomaterial, promise a total bone reconstruction that has been impossible to achieve previously,” said Ralf Smeets of the University Medical Centre of Aachen.

The basic structure of the new material consists of synthetic polylactide (PLA) with tricalcium phosphate (TCP). This provides a degradable implant, which the body catabolises as the natural bones regrow. However, the material can only be applied in places where it will not be subject to severe stress. This means the Resobone implants are mainly suitable for replacing missing facial, maxillary and cranial bones.

The implants are currently able to close fissures of up to 25 square centimetres in size. The unique structure is based on a manufacturing process developed at the Fraunhofer Institute for Laser Technology called Selective Laser Melting. In this process a laser beam melts the pulverised material layer-by-layer, leaving a porous structure with channels as small as 80 to 100 micrometers.

Computer tomography images of the patient provide the template for the precision-fit production of an implant. The work processes, from the tomography imaging, to construction of the implant, through to its completion, are coordinated such that the replacement for a defective bone can be produced in just a few hours, while a five-centimetre large section of cranium can be done overnight.

In addition to medical 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,” explains Simon Höges, Project Manager at ILT.

In addition, fewer procedures are necessary because the surgeon no longer has to take replacement bone from the patient’s pelvis. Similarly, there is no need for 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,” explains Höges. The technology is now available to project partners for application.

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