Additive manufactured implant made of a biocompatible titanium alloy.

A patient in Argentina has been able to lead a normal life again after an additively manufactured titanium cranial implant structure helped him recover following stroke related surgery.

Advances in additive manufacturing have enabled some life changing applications in the medical industry in recent years. Its ability to offer unmatched precision and development in biocompatible materials make the technology a suitable choice for the manufacture of complex and custom solutions in patient specific applications.

In this particular case, certain mechanical requirements had to be met to ensure a successful result. To allow brain fluid to pass through, a fine mesh structure had to be constructed with pores measuring approximately 1 mm across, with links at around 0.2 mm thick, resulting in 95 per cent porosity. In addition to this, the structure had to allow room for the bone to grow into it.

The process began with Novax DMA in Buenos Aires, a specialist in the development and supply of medical implants for traumatology, orthopaedics and craniofacial surgery. 3D design was then carried out using software from UK company, Within.

“We have been supplying medical implants since 1995,” Daniel Fiz, CEO of Novax DMA, explained. “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.”

Porosity of the implant is 95 per cent, so liquids can flow through with minimal resistance.

Once the CAD model was completed, Munich based, Alphaform AG, manufactured the implant using EOS metal additive manufacturing machine, EOSINT M 280. The process took just a few hours to complete and the implant was waiting in the operating theatre within three weeks.

“We had already successfully completed many additively manufactured products in the EOS system,” Christoph Erhardt, Director of Additive Manufacturing at Alphaform, commented. “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. We 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 patient's skull.

Christoph Erhardt added; “For us, additive manufacturing and EOS are synonymous. We have already produced an enormous number of parts for many companies. Both we and our customers are continually amazed by the application possibilities and the high-quality production that can be achieved. That was once again the case here. We were able to help a person to live a normal life, on an on-going basis, despite their having suffered a very serious injury.”

The one-and-a-half-hour surgical procedure was carried out successfully in May last year. The patient left hospital after two days and the wound healed within three weeks.

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