patient in Argentina required a particularly large cranial implant after
stroke-related surgery, placing stringent requirements on the manufacture of
the prosthetic. Naturally it needed to fit precisely, but in this case it also
had to be permeable to allow brain fluid to pass through. Minimal heat
conduction to the cerebral tissue was important, especially in a sunny climate.
Additionally, biocompatibility was needed to allow the bone to grow into the
edges of the implant.
additive manufactured implant made of a biocompatible titanium alloy was placed
in the skull of an Argentinian patient during stroke-related surgery.
titanium alloy lattice structure secured by screws directly into the skull was
deemed to be ideal. It was additively manufactured layer by layer from metal
powder in a machine produced by German firm EOS. Time was of the essence in
producing the implant. The process was started by Novax DMA in Buenos Aires,
which specialises in developing and supplying medical implants for
traumatology, orthopaedics and craniofacial surgery. For the 3D design of the
implant, software was employed from UK company Within, which allowed the basic
form and porous structure to be defined quickly. As soon as the CAD work was
completed, Alphaform AG, near Munich, manufactured the implant in a matter of
hours in an EOSINT M 280 metal additive manufacturing machine from EOS.
of the implant is 95 per cent, so liquids can flow through with minimal
resistance, temperature is controlled and the bone tissue coalesces with the
stringent mechanical requirements had to be met to ensure a successful result
and technological advances in additive manufacturing allowed them to be
achieved. The pores in the implant are approximately 1 mm across, while the
links are about 0.2 mm thick, resulting in 95 per cent porosity. To achieve
such a fine mesh in a rigid structure to tight dimensional and profile
tolerances would be impracticable using conventional, subtractive production
techniques. The implant was in the operating theatre less than three weeks
later, with transportation consuming one-third of that time. The
one-and-a-half-hour surgical procedure was carried out successfully in May last
Erhardt, Director of Additive Manufacturing at Alphaform, commented, “We
had already successfully completed many additively manufactured products in the
EOS system. However, we are particularly proud of this implant, not only
because of the precise realisation of the form, but also because we were able
to optimise the porous structure and the difficult process of cleaning the
small interior spaces.
developed a multi-step process of abrasive and mechanical cleaning, rinsing and
ultrasonics to arrive at the required level of medical purity, which is vital
as particles can dislodge with the slightest movement, leading to the
possibility of infections or rejection.” The level of cleanliness was
verified by extensive tests, including particle and cytotoxicity testing.
Gas-chromatography analysis was also performed. Other tests confirmed that the
implant fulfilled the necessary requirements to stabilise and protect the
Fiz, CEO of Novax DMA, added, “Additive manufacturing represents a new
milestone for patients. It offers optimal biomedical characteristics together
with the highest levels of compatibility, thereby having a lasting effect on
improved quality of life. “For these reasons, we have applied the
technology with success to other areas of the body. Alphaform has also
manufactured jaw implants for us, as well as a hip joint and a spinal implant.
For the latter, we are currently considering series production using additive
patient left hospital after two days and the wound healed within three weeks.
Since that time there have been no complications and the patient has been able
to lead a normal life. Christoph Erhardt concluded, “That was once again
the case here. We were able to help a person to live a normal life, on an
ongoing basis, despite their having suffered a very serious injury.”