Additive technology more typically associated with the aerospace industry was recently used by a cross-disciplinary team of doctors and engineers in Mexico to produce a cranial implant for the victim of a shooting.
The implant was made on a laser sintering machine supplied by German additive manufacturing specialist EOS more typically used to produce aerospace components. The system – an EOSINT M280 DMLS – uses a high intensity fibre laser to melt fine titanium powder particles and build up a product layer by layer.
The prosthesis was designed free of charge using Vero’s VISI CADCAM package, by designers and engineers from Vero’s Mexican reseller, VISI Series México. The team comprised Raúl Moreno, Salvador Enriquez and Elĺas Hernández. VISI Series México collaborated on the project with the Advanced Human Bioengineering Foundation for Latin America (BHA Foundation).
At the start of the design process an STL file of the entire head was provided by the medical team and was produced by the CT/MRI scanner. The STL file was used to 3D print an internal plastic prototype model to analyse the shape of the hole. Working with the doctors, the prototype model was reworked to create a nicer uniform hole with no fragments. Once happy with the topology of the skull, the prototype model was scanned and imported into the VISI CAD application.
From there, a network of curves was taken from the good side on the skull and mirrored onto the left side to cover the aperture. Then a surface model of the prosthesis was created and the doctors were again consulted to help determine the ideal fixing structure and screw locations and to ensure that the model conformed to the needs and complexities of cranial anatomy. At this point, a plastic prosthesis was printed for assembly to the head prototype to check for alignment and fitting. With a design finalised, the prosthesis was sent to the USA for printing.
Project Director Dr Gilberto Lopez – a specialist in oral and craniofacial rehabilitation – worked with experts in neurosurgery and maxillofacial surgery, regarding the cranial implant design, and successfully prepared the surgical titanium prosthesis model.
Commenting on the prosthesis design, Elĺas Hernández said “We worked closely with the medical team to perfect the design. The holes and fixing structures all serve a purpose. It was important that the design would interact naturally with the human body, allowing fusion of bone tissue and fluid flow within the cranial cavity. Because the prosthesis is metal, it must also allow for low heat dissipation around the brain.
Lasting four hours, the surgical procedure was carried out at a public hospital in the Mexican city of San Luis Potosi, by a team of neurosurgeons, maxillofacial surgery and oral rehabilitation specialists, who also worked free of charge.
Raúl Moreno, Director General at VISI Series México says: “A number of countries, including England, the United States, China and Spain, are already starting to use this type of technology for patients with congenital or acquired craniofacial deformities.
“The process gives the ability to design and manufacture custom prostheses quickly and safely, which are both functional and aesthetical, considerably improving the patient’s quality of life. And Mexico is now finding a position amongst the pioneers of custom titanium prostheses. The fact that a group of technicians and physicians can selflessly contribute in this way to benefit our society is a great source of pride.”