Surgeons today essentially decide between three types of craniomaxillofacial implants: plastic implants, for example, made of polyether ether ketone (PEEK), deep-drawn metal sheets, titanium mesh, titanium solid and now, additively manufactured titanium implants.
Due to its excellent biocompatibility and high resistance to corrosion, titanium is a popular material choice in the medical field. Other than PEEK, where there is absolutely no bone ingrowth, titanium allows the bone to grow and is, therefore the perfect material for implants in combination with lattice structures made by additive manufacturing. Depending on the application, titanium implants are likewise developed individually and manufactured conventionally as a mesh or as a high-strength solid reconstruction version.
To manufacture patient-specific implants, Frank Reinauer, Head of Innovation and Production of Biomaterials at Karl Leibinger Medizintechnik, now relies on additively manufactured implants. The name Karl Leibinger Medizintechnik has been synonymous with implants in craniomaxillofacial surgery since 1979. Karl Leibinger Medizintechnik is a company that belongs to the KLS Martin Group.
For Reinauer, the obvious thought was why manufacture by conventional means if an additive approach was also possible? “We have of course had our eye on the additive approach. But we also had very precise notions of what the machine needed to do. After the first decade of 3D metal printing, the time seemed right to get involved.”
However, initially there was the hurdle of investing in AM (additive manufacturing) to overcome. “If you make a decision based purely on economics, then you shy away from the risk and tell yourself to let others try it first,” adds Reinauer. “The decision to get involved was made for strategic reasons, and this was absolutely the right decision. We purchased our first AM machine from Concept Laser in 2013.”
An additively manufactured titanium implant for an individual patient is a giant leap forward for clinical practice. The increasing spread of these implants around the world is also reflected in the fact that they are now a significant revenue driver for the company.
Embarking upon additive manufacturing with metals
When engaging in 3D metal printing, Reinauer found it was necessary to overcome initial hurdles in process validation. “It took us around nine months to get through this preparatory phase because the regulations and general conditions in medical technology are meticulous.”
Initially the CE mark must be acquired. In addition, DIN Standard 13485 and the guidelines of the United States Food and Drug Administration have to be met. The versions of the Medical Devices Act and the Medical Devices Regulation (MDR) also provide a basis. In addition, there are audits by authorities that must be undergone.
Titanium as the benchmark: implants made to measure
After Karl Leibinger Medizintechnik started using 3D metal printing, it quickly became apparent that laser melting was the method of choice for titanium osteosynthesis. Now it is even possible to produce large-scale reconstructions with complex geometries.
In addition, the geometric freedom caters to specific aesthetic requirements. For the surgeon, it is not just about restoring functionality, but also always about the aesthetic look. The parts have high strength, and the material is biocompatible.
“From numerous aspects we view titanium as the benchmark for implant technology,” says Reinauer.
Additive manufacturing with metal also offers the opportunity to manufacture specific partial surface roughnesses of the implant so that it can fuse with the bone quickly at the edges of the implant.
“But there is another important aspect in favor of additively manufactured titanium implants, the patient-specific geometry and precision fit,” says Reinauer. “Ultimately this means a high level of functionality.”
The surgeon can use imaging techniques such as CT (computed tomography) or MRI (magnetic resonance imaging) to cater for the specific anatomy of an individual patient. The engineers from Karl Leibinger Medizintechnik process these data to create STL data, which serves as the initial data for 3D construction and manufacturing on a M2 cusing from Concept Laser.
The manufacture of laser-melted individual implants
The parts are built up on the M2 cusing, where even large-scale parts can be accommodated in a build envelope of 250 x 250 x 280 mm³. The M2 cusing is designed with ATEX guidelines and thus makes it possible to process reactive materials like titanium or titanium alloys safely.
“When it comes to processing reactive materials, Concept Laser has undoubtedly set the benchmark for safety and with a contamination-free concept for manufacturing additive parts,” says Reinauer.
Like all machine solutions from Concept Laser, for reasons including user-friendliness and safety, the M2 cusing features physical separation of the process chamber and handling area. It is robust and suitable for 3-shift operation. After the parts have been built up, the parts are heat-treated to reduce tension, and then sterilized and packaged in a Class 7 cleanroom.
Demand is growing
The use of these implants is expanding. There are currently more than 20 engineers employed worldwide on handling assignments for clinics. Karl Leibinger Medizintechnik offers surgeons a transparent order handling system. It is a web-based platform controlled with an APP. On the clinic site, the surgeon stipulates the patient data, geometric demands and the date of the operation. In addition to the patient-specific implants, anatomical models for optimum pre-surgical planning can also be requested on this site. It is often also necessary to cater for special requests in the construction, for example, tumor removal needs to be planned.
For complicated interventions, Karl Leibinger Medizintechnik offers a complete implant kit that can be installed quickly and precisely in an operation. Before making the decision to fabricate, the doctor sees a draft design and a price quotation. This means the company can supply additively manufactured implants for an operation within a week. The specific geometry and precision fit are crucial in the operation because they shorten the operating time, reduce the risk of the operation, and the surgeon can concentrate on the actual operation itself. The patient benefits from a safe operation and a quicker recovery.
Aspects of additively manufactured, patient-individual implants made of titanium include:
–Freedom of geometry and a precision fit affect function and aesthetics
–Large-scale, complex structures are possible
–Definable edge and surface texture ensure good bone ingrowth
–Prompt, no-tool manufacturing and rapid process chain
–Quicker patient recovery
–Ultimately relieves the strain on the healthcare system
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