- Additive manufacturing techniques make possible innovations in implant technology using titanium
- Elastic disc implants from Tsunami can be additively manufactured “in a single-shot process”
Lichtenfels, 15 December 2014: Having a “strong backbone” is not only figuratively speaking a positive personal characteristic. Physically speaking too, a healthy spine is very important for quality of life and personal mobility. One way to alleviate spinal issues is by using minimally invasive technical components made of plastic or metal that are implanted in the body. For spinal surgery patients and surgeons, these implants can be a blessing: with just minor surgical intervention, they help patients become able-bodied again by regaining full confidence in the supportive functions of their spines. Behind these implants lies a combination of design, functionality and a great deal of manufacturing expertise. We spoke to Stefano Caselli, CEO of Tsunami Medical Srl based in Modena, Italy, about trends and product development in spinal implants.
Tsunami sees itself as a system developer for spinal implants. Thus it offers implants that restore the functionality of a damaged spine as well as tools or instruments that allow surgeons to conduct a successful operation. The aim is to strengthen the spine and thus ensure the mobility of the patient.
Conventional spine cages
Spine cages are implants for levelling and relieving the pressure on the spine. These implants are minimally invasive normally used in conjunction with screws made of Titanium in patients with problems caused spinal instability stenosis or many others spinal degenerative dieses.
The cages themselves are made of PEEK (polyetheretherketone), a highly biocompatible material, even for allergy sufferers. In the past, these cages were manufactured conventionally in titanium, with the result being that, in some cases, the titanium component had a negative impact on the bone structure due to the rigidity of the cage realized by drilling with a very hard structure. This was caused by the implant’s significantly lower elasticity versus the bone.
One alternative is PEEK, a high-performance plastic with compression properties or elasticity (E-module) rivalling that of bone. In addition, PEEK components cause no artefacts in MRI (magnetic resonance imaging) and are thus easy to locate by the surgeon through imaging. One of the disadvantages of PEEK spine cages is their inability to be integrated into the bone structure and their eventual should slip off from the original position also after longer periods of implant. Polyetheretherketone is a high temperature resistant thermoplastic and belongs to the group of polyaryletherketones. Its melting temperature is 335°C.
Modern, laser-melted spine cages
The LaserCUSING additive laser melting method combines the strengths – and eliminates the weaknesses – of traditional titanium or PEEK components for spine cage applications. A laser-melted component can now offer the biocompatibility of titanium with the desired elasticity of a plastic material in a single product. Laser-melted spine cages have a very complicate geometry and not require to be re-treated to ensure an optimal surface structure. The highlight of this solution: its geometry, with partially different density distributions (embedded web-like structures), now gives titanium parts the same elasticity as a PEEK solution.
Laser-melted cages can also be affordably manufactured in various dimensions depending on the anatomy of the patient, allowing for customized manufacturing. According to CEO Stefano Caselli, laser-melted cages represent “a true innovation that combines material-specific advantages such as biocompatibility, i.e., the ability to embed the material into the bone structure, and elasticity that is customized for the human body in a single product”.
Surgeons can easily locate the cages using CT or MRI imaging. Laser melting also allows custom or small-series manufacturing, including “made-to-order” cages for patients with special anatomical conditions or standard solutions for other patients. A clinical study conducted in March 2014 in cooperation with Carl von Ossietzky University in Oldenburg, Germany, confirmed an excellent healing prognosis with these implants. (*Oldenburg study)
“Lobster spacers” as mobile functional elements in spinal primary instability
Caselli described another Tsunami innovation – so-called “lobster spacers”– self-spreading spacers that can be used between intervertebral discs in surgical spinal column reconstruction. The spreading mechanism developed by Tsunami is something of a miracle of manufacturing: it consists of a gearbox with a central screw and side gears that spreads apart two wings.
Creating lobster spacers with perfectly aligned surfaces is possible thanks to the LaserCUSING process, using an Mlab cusing R system from Concept Laser. Its highly smooth – nearly polished – surface ensures significantly less excrescence in the tissue. A remarkable aspect of the manufacturing technology, according to Caselli, is the ability to produce multiple copies of this complex, movable part at the same time.
“LaserCUSING gives us time advantages, advantages in cost structure and is also much easier, under cleanroom conditions, than conventional manufacturing strategies. In addition, machine solutions from Concept Laser provide excellent performance and a high level of safety when working with reactive materials such as titanium or titanium alloys.”
New development: disc prosthesis as a single component
When it comes to component design, additive manufacturing can open up entirely new directions. Another innovation that has resulted from the opportunities offered by LaserCUSING at Tsunami is the development of a customized disc prosthesis that acts as a vertebral spacer to strengthen the spine.
It consists of an upper shell and a lower shell connected by a double spring. The shells’ surface is designed to fit perfectly into the vertebral plate. The double spring is made of titanium with a silicone core for damping the movement of the spring. The design and spacing dimensions can be adjusted precisely to the patient’s anatomy in accordance with the surgeon’s specifications. The highlight of this innovative solution: the disc prosthesis is manufactured in a “one-shot” process using laser melting technology, a solution that eliminates the need for downstream assembly processes.
Functions of the disc prosthesis in detail
Tsunami’s competencies were put to the test early on. First, it had to translate its experience in spinal implants into a product solution that would increase patient mobility. The disc prosthesis ensures 360-degree freedom of movement, providing enormous support to the patient’s mobility. Optimum elasticity is ensured by the double spring and enhanced through the silicone core. The company also needed a engineering solution that made the most of the geometric possibilities offered by the LaserCUSING method.
Stefano Caselli: “From a design standpoint, the disc prosthesis as a product idea is the direct result of the geometric freedom and functional integration offered by the LaserCUSING method. Conventional manufacturing methods don’t work for this kind of solution. Additive manufacturing complements our expertise in spinal column reconstruction by offering a multitude of new options. The solution is also very flexible: we can adjust the dimensions to a patient’s specific anatomical profile.”
Commentary on the clinical study by Dr Thomas Failing at Carl von Ossietzky University of Oldenburg, Germany, in March 2014:
Title: Study of dose enhancement with EBT3 films and artefact generation in CT images in the vicinity of spinal implants
“Overall, this clinical study showed that the dose enhancement and CT image artefacts generated by titanium implants are not to be underestimated and must be included in the clinical treatment plan. Structured implants are a useful approach for minimizing these risks, with the potential for transfer to other areas of implantology.”
Interview with Stefano Caselli, CEO of Tsunami Medical Srl
Question: How do new product ideas arise at Tsunami?
Stefano Caselli: We focus on system competencies in implant technology with a focus on spinal reconstruction. This includes implants and tools for surgeons. It’s important to think “material-independently”. The solution could involve polymers or metals. As the disc prosthesis shows, a hybrid solution combining metal and silicon is also a possibility.
What’s important is understanding the application. This helps us employ the right design and production method to create the perfect solution. This solution must be functionally impressive and economically feasible. Of key importance here are bionic approaches to design that support the compatibility of the implant as a foreign body inside the human organism. Nature is a good teacher for us. The experiences of the past are a treasure chest of knowledge from which new ideas can spring.
Question: How did you learn about the laser melting process?
Stefano Caselli: In the field of implantology, two materials are dominant: metal and plastic. Plastic is typical injected into a mould. With metals, so far we’ve had only casting or milling as options. Casting in turn requires moulds, and milling produces waste, which impacts the cost structure of the final product. As a supplier, part costs are of course crucial to the viability of the product on the market. With LaserCUSING, we have completely new options in geometry, with no need for moulds, without waste, and with the ability to produce batches of any size. Last but not least, our spinal implants can be individually customized to the patient’s anatomy in terms of elasticity and size. The benefits offered by laser melting of metals became apparent very early on.
Question: When did you actually begin employing the process?
Stefano Caselli: That was in 2010.
Question: What has been your experience since then?
Stefano Caselli: Tsunami is located in the region of Modena, Italy’s “Biomedical Valley”. As such, many of our colleagues have experience in laser melting. In medical technology, titanium is very popular. It is biocompatible and well tolerated by allergy sufferers. However, for processing purposes, it’s important to remember that titanium and titanium alloys are reactive metals. This requires system technology with strict safety measures. I’d heard of fire damage from titanium production in the Valley, so I was initially very cautious. Thus began an intense search for a safe and reliable system technology.
Question: Is this how you happened upon Concept Laser?
Stefano Caselli: As I said, we had our sights set on titanium from the beginning – in the human body, it’s a fantastic material that adapts perfectly to the bone structure. For this reason, we put every offer from every supplier under the microscope in terms of safety.
With Concept Laser, represented in Italy by Ridix, we noticed a couple of interesting points. These included the closed system, which prevents oxygen contamination, and their high level of expertise in material validation and certification, an extremely important service for us as users. However, the deciding factor was the safety aspect in processing reactive materials. Concept Laser has worked hard to implement the EU’s ATEX guidelines into its system technology. Replacing the filter is very safe, to name a practical example.
Question: What systems do you use?
Stefano Caselli: To manufacture our products with the laser melting process, we use the Mlab cusing R system from Concept Laser. The machine is very easy to use, meets the necessary safety standards for working with reactive materials and offers very high precision.
Question: How do you see the future prospects of laser smelting?
Stefano Caselli: Additive manufacturing is undoubtedly the way of the future. Users need to understand that laser melting will make conventional design concepts obsolete. It makes absolutely no sense to copy a conventional part. What we need here is new approaches to design – in terms of time, cost structure and the level of precision that can be achieved today. There’s no way around the financial considerations. I expect system technology to advance quickly: multiple-laser technology, higher-capacity lasers or larger available space are the key words I’m hearing from the market. All signs indicate that there’s still much room for improvement in terms of the level of precision and the assembly speed for components.
Thank you for talking with us.
About Tsunami Medical
Tsunami Medical Srl in Modena (Italy) was founded in 1997. Founder and CEO Stefano Caselli and his team initially operated as a subcontractor for companies in the invasive diagnostic equipment industry. Over time, it developed competencies in two key areas: biopsy and vertebroplasty (a minimally invasive medical procedure used to treat vertebral compression fractures). The company’s primary markets are South America, Europe and Russia.
Its production is based in the heart of Italy’s Biomedical Valley. As a certified manufacturer of medical applications, Tsunami follows the ISO 13485 standard. In a production space covering 1,200 m² with ISO cleanroom classification, it uses modern machine technology to process plastics and metals using an additive laser melting process.
In 2010, Tsunami began developing and manufacturing MLS spinal implants. To create laser-melted product solutions, Tsunami uses the Mlab cusing R system from Concept Laser.
The privately held company currently has 25 employees.
Systems percutaneous discectomy (PPD) (for herniated discs), biopsy needles, spinal implants, bone cement mixers and injectors, transplantation needles and kyphoplasty balloons (for the treatment of vertebral fractures)
Concept Laser GmbH
An der Zeil 8
Phone +49 (0)9571.1679 – 0
Phone: +49 (0) 9571 / 1679 251
Represented in Italy by:
Via Indipendenza, 9/F
I-10095 Grusglaiasco (TO)
Tel.: +39 011 4027511
Tsunami Medical S.r.l.
Via Spallanzani 7
I-41036 Medolla (MO)
Reference Keyword: LaserCUSING®
The LaserCUSING® process is used to create mechanically and thermally stable metallic components with high precision. Depending on the application, it can be used with stainless and tool steels, aluminum and titanium alloys, nickel-based superalloys, cobalt-chromium alloys or precious metals such as gold or silver alloys.
With LaserCUSING®, finely pulverized metal is fused using a high-energy fiber laser. After cooling, the material solidifies. Component contour is achieved by directing the laser beam with a mirror deflection unit (scanner). Construction takes place layer by layer (with each layer measuring 15-100 microns) by lowering the bottom surface of the construction space, then applying and fusing more powder.
Concept Laser systems stand out due to their stochastic control of the slice segments (also referred to as “islands”), which are processed successively. The patented process significantly reduces tension during the manufacture of very large components.
About Concept Laser
Concept Laser GmbH is an independent company based in Lichtenfels, Germany. Since its founding in 2000, it has been a leading innovator in the field of laser melting with the patented LaserCUSING® technology across many industries.
The term LaserCUSING®, a combination of the C from CONCEPT Laser and the word FUSING (to fully melt), describes the technology: the fusing process generates components layer by layer using 3D CAD data. The method allows the production of complex component geometries without tools to create parts that are difficult or even impossible to achieve through conventional manufacturing.
With the LaserCUSING® process, conformal cooling can be used to create tool inserts as well as direct components for the jewelry, medical, dental, automotive and aerospace industries. This applies to prototypes and series parts.
The company offers both standard systems and custom concepts for metal laser melting. With Concept Laser, full-service as an option means that customers can either purchase their own metal laser melting systems or rely directly on service and development services.
Laser machining systems from Concept Laser process powder materials made from stainless steel, hot work tool steels, cobalt-chromium alloy, nickel-base alloy as well as reactive powder materials such as aluminum and titanium alloys. Precious metals such as gold or silver alloys for jewelry making are also an option.
LaserCUSING® offers new perspectives in terms of cost and speed for efficient product development in industries such as:
- Medical and dental technology
- Aeronautics and space industry
- Tool and mold construction
- Automotive and racing
- Mechanical engineering
The systems reduce development time and costs substantially while offering much greater flexibility in product development.
The high quality standards, level of experience and successful track record of Concept Laser guarantee reliable and cost-effective solutions with proven performance in daily production, with a particular focus on unit cost reductions.