The Instituto de Biomecánica de Valencia (IBV) participates in this project with a group of partners with the purpose of defining the non-geometrical requirements for customized products. When trying to satisfy user comfort, it is not only necessary to consider the geometrical requirements and a good product fit, moreover it is necessary to consider non-geometrical requirements that define the interaction in the zones of contact such as pressure distribution between the product and the human body, or the comfort felt by the user while he is using the product. Furthermore a methodology has been developed using rapid manufacturing which permits the manufacturing of product parts from CAD designs.
The mandible implant has been chosen as one of the test benches to try out this new manufacturing technology, together with knee implants, trans-femoral prosthesis, and two consumer goods, motorbike seats and motorbike helmets, products that are well suited to be customised to meet individual body shapes.
The Custom-Fit way to manufacture a mandible implant takes advantage of the best available technologies in design, in material science and in manufacturing, thanks to the member partners of the Custom-Fit consortium.
The process is the following: The jaw bone geometry is studied through Computerised Tomography, CT images are then worked using specialised software - Mimics by Materialise - capable of extracting the jaw bone surface in a standard file format for later surface design which uses Standard Triangulation Language (STL). This is capable of distinguishing the damaged part of the bone from the healthy one.
Then, a surface model of the implant, which has to replace the damaged bone part, is easily designed with a CAD system - 3-matic, by Materialise in Germany - that allows the direct playing with facet models (STL-files) avoiding the conversion to CAD-surfaces, which normally requires a long computer processing time; this dramatically shortens the implant design phase. Here, engineers and surgeons work in collaboration to decide were to cut the jaw and consequently the size of the scaffold.
The 3D model of the implant is then completed by adding the internal structure, i.e. adding porosity using more design software called Innerspace that was developed by the Custom-Fit partner, TNO, in The Netherlands.
Finally the model is sliced ready to be manufactured on a special Rapid Manufacturing tool, capable of printing multi-material and porous objects, using high viscosity resins, the Inkjet Printing tool also developed by TNO.
And one of the resins printable by IP is the bioreabsorbable resin developed by DSM, a German company and Custom-Fit partner, that is responsible for new material development. First samples have been successfully printed. It will take years for the new scaffolds to be approved for implantation in human beings, but the approval procedure has now been started, with In-Vitro Cytoxicity tests.
Several advantages will be brought about by bioreabsorbable scaffolds: no rejection of the foreign material, new bone will be able to grow over time (for children), further treatment like dental implants will remain possible and definitively the implant will not be a foreign object any more, but will be completely replaced by new natural bone. It is a revolution in implant surgery, Custom-Fit made the first step.
Custom-Fit is an industry led project to investigate the possibility of moving towards knowledge based manufacturing and customised production through integration of knowledge in Rapid Manufacturing, Information Technology and Material Science. Funded under the Sixth Framework Programme, the project with a period of four years and a half involves 30 partners from around Europe. The aim is to create a fully integrated system for the design, production and supply of individualised products. It has targeted products for implementing the new technology, including motorcycle seats, helmets, implants and prosthesis. More information is available at the Custom-Fit project website.