Conventional subtractive metalcutting has traditionally been used to manufacture such custom implants. However, certain shapes are impossible to manufacture sufficiently accurately, necessitating manual work by the surgeon during the operation. Moreover, the process is limited in what it can achieve and tends to be lengthy and expensive.
“We wanted to explore the potential of additive manufacturing technology for implantology and at the same time develop solutions that were both helpful to patients and economical,” said associate professor Radovan Hudak, MD. “It was necessary to explore the limits of the technology and its potential as well as to discover the optimum process and find a suitable material.
“Precision, reproducibility and surface quality were all high on the list of requirements, along with a production process that was as free as possible from production errors.
“The main aim was then to acquire state certification for cranial, jaw, and facial bone implants.”
Hollow lattice structure
For manufacturing the first implant, the task was to produce a piece of replacement cranium approximately 15 cm across from titanium Ti-6Al-4V, a biocompatible standard alloy in medical technology with improved mechanical characteristics.
The team used the results of a computed tomography examination of the patient. Data transformation to a CAD program and design and manufacture of the implant all took place at CEIT.The 1.5 mm thick implant weighed 63 grams. A notable feature was the hollow lattice structure, which promotes in-growth of bone tissue and allows the integration of micro-sensors for recording medical data.
The process has now received registration from the Slovakian State Institute for Medicinal Control for the manufacture of implants for cranial, facial and jaw applications. This resulted in official EU-wide approval. Negotiations with the largest national insurers with respect to cost also proved successful.
This type of implant benefits from higher precision and a lower error rate in production, resulting in fewer side-effects and quicker recovery for the patient. When the wound has healed, the evidence of the procedure is far less noticeable, helping the individual’s subsequent state of mind.
CEIT is now producing bespoke implants as well as undertaking series manufacture of standard implants using EOS additive manufacturing technology.
“We are able to meet the technological criteria and manufacture extremely thin walls with the necessary uneven surface geometries,” added Professor Hudak. “In addition, it is possible to introduce cavities into the implants, such as shapes comprising complex hollows or canals. Lattice structures have become a key element in the scope of the possibilities.”