Lithoz
Bioabsorbable bone replacements which can be 3D printed to suit individual patients: to the general public, this might seem like something out of a science-fiction movie. Speaking to Lithoz in 2023, it’s a reality.
Last year, the ceramics 3D printing company announced the development of its new material, LithaBone HA 480, a bioabsorbable bone graft substitute based on hydroxyapatite, a natural mineral that is the major element of human bone.
The new material enables easier-toclean parts with higher wall thicknesses than previous Lithoz bone replacement materials, from 1.6mm to 10mm, as well as strongly reduced overpolymerisation, according to the company, and a ten-fold longer shelf life.
Traditionally, bone implants would not be able to grow with a defect. Daniel Bomze, Lithoz Director of Medical Solutions told TCT about the difficulties of this: “Think of a small child having an accident and needing this treatment. Normal implants will not grow with a defect. After some time there’s two choices, you will leave it in there, then you will get some kind of deformation or gaps, or you need to take it out. For example, children can have hydrocephalus, where parts of the cranium need to be removed. Once its closed back up again you use approximately 100 to 120 screws. So imagine this child is growing and after some time you need to remove 120 screws that already have been partly incorporated, and you need to replacement the implant. This is not something that you want to do to your children or to any children.”
Bomze told TCT that although subtractive manufacturing methods do work for creating bone implants, such implants are limited to simple geometries. While the outer geometry can be shaved according to the patient’s anatomy, the inner part of the implant, a three-dimensional controlled, open, porous interconnected network, can only be manufactured with 3D printing.
This interconnected network is necessary for blood vessels to grow into the pores for the transportation of bone cells. The bone cells then sit on the bone replacement material, according to Bomze, and effectively suck themselves to the surface. The cells then ‘spit’ an acid that dissolves the implant, so the body can resorb the dissolved material.
“You can now actually manufacture implants with 3D printing and generate those open, porous, interconnected networks which allow the ingrowth of the bulk of the blood vessels and the removal of metabolic products, which is important for the healing process,” Bomze said of the benefits. “There’s other ways to shave these materials, but only additive manufacturing allows you to create the geometry of the pore and the connection between the pore.”
For the new Lithabone HA 480, Lithoz worked with users of previous bone graft substitutes. Bomze revealed that how this input from previous users allowed the company to improve on limitations of other materials, such as being only developed for delicate 3D meshes which meant that a
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Exhibit at the UK's definitive and most influential 3D printing and additive manufacturing event, TCT 3Sixty.
closed surface design could not be achieved due to the stiffness of the material.
Another challenge, according to previous users, was storage, as Bomze explained: “Here we use rather coarse particles, and we had some issues with stabilisation of the suspension, that means we needed to ship the material deep frozen all over the globe, which of course was quite expensive for the customer, and we could get rid of that which is a huge advantage.”
Speaking about its future development and application opportunities, Bomze added: “What I think people should really look out for is what the customers of Lithoz are bringing out in the next few months because we’re just the ones that offer the technology for it, but they offer the actual solutions that help patients. There will be things in the near future that will be published, and people should keep an eye on what’s coming out there. I think this will definitely change the view of what the 3D printing of ceramics can do for patients and for surgeons.”
