How the collaboration between KLS Martin and Lithoz led to hundreds of patient-specific ceramic implants

The origin story of KLS Martin’s ceramic additive manufacturing program begins in a Viennese pizzeria. It was there, over 12 years ago, that Frank Reinauer, Senior Director Division Implants at KLS Martin, and Johannes Homa, Co-founder and CEO of Lithoz, first mapped out the idea of applying 3D printing to medical applications. By that point, Reinauer had already been at KLS Martin for several years, having entered the company as a mechanical engineer responsible for resorbable materials and storage systems for instruments and implants.

But the company’s AM program began even earlier. The initial goal was to work on verification. Surgeons needed something tangible to plan and discuss complex procedures, and resin models produced on KLS Martin’s first polymer system—acquired in the early 2000s—gave them exactly that. “The surgeon likes to have something in their hand,” Reinauer said. “There’s nothing that you can measure like an engineer with a caliper.”

That hands-on utility established an early foothold, and the team’s thinking quickly moved beyond models. If 3D printed geometry could verify an implant’s fit against a patient’s anatomy, Reinauer reasoned, it might also serve as the production method itself.

Titanium, ceramics, and regulatory patience

KLS Martin acquired its first titanium machine in 2007, at a time when additive manufacturing was still largely associated with rapid prototyping rather than regulated medical production. Validation alone consumed years before the machine could be used for clinical output — an experience Reinauer credited with giving KLS Martin a high tolerance for lengthy technology adoption cycles. “Due to that experience, we are not scared about implementing a new technology,” he said.

The ceramic chapter opened through the same collaboration with TU Wien that had shaped KLS Martin’s earlier polymer work. Reinauer and Homa chose beta-tricalcium phosphate (TCP)—a Class III medical device material, the highest regulatory classification—as their first ceramic target. Clearing that classification with the notified body required roughly two years of documentation, animal testing, and process validation, even with substantial prior quality paperwork in place. “The quality of the auditors is increasing because they learn,” Reinauer noted, recalling that regulators examining ceramic additive manufacturing processes seven or eight years ago had almost no reference framework for what they were reviewing.

Ceramics carry specific properties that make them clinically attractive beyond biocompatibility alone. Their low thermal conductivity means patients do not experience the cold sensitivity associated with metal implants—a quality-of-life consideration Reinauer highlighted directly: “If you have implants here and you go out into the cold in the winter, it hurts. You could feel the cold.” For pediatric patients, the issue compounds further, as a non-resorbable device implanted in a growing child will eventually need to be addressed as the patient grows. Resorbable ceramics sidestep both problems: the material dissolves as bone regrows along its guide structures, eliminating the need for a second surgery to remove the implant.

Homa offered a direct rationale for ceramics’ biological compatibility: “If you look into nature, there is no plastic in nature. There are no metals—just precious metals, gold and silver. All metals are usually oxides. Ceramics are abundant. That’s my explanation always for why the body prefers ceramic: it’s a natural material.”

The material comparison across KLS Martin’s three lines — resorbable polymers such as PDLA, titanium with lattice structures designed for osseointegration, and beta-TCP ceramic scaffolds — also revealed clinically distinct roles rather than a simple hierarchy. Beta-TCP resorbs as bone remodels around and through it, making it suitable for gap-filling in areas where the goal is to restore natural bone rather than provide permanent load-bearing support. For indications requiring both, KLS Martin developed a hybrid construct: a ceramic scaffold handles the regenerative portion while a titanium component carries structural load. For the most acute trauma cases, where stabilization takes priority over biology, titanium remains the appropriate choice.

Reinauer walked through the clinical pathway that led KLS Martin into ceramics. The company’s entry indication was mandibular correction, specifically gap-filling in patients undergoing osteotomy to address sleep apnea by repositioning the jaw. Surgeons splitting and advancing the mandible can create bone gaps that, without intervention, require harvesting bone from a secondary donor site, typically the hip. “Most of these indications end up with the patients suffering much more with the harvesting area,” Reinauer said, making the ceramic scaffold a meaningful clinical alternative. From that starting point, KLS Martin expanded coverage to the orbital region, forearm, and upper extremities, with ongoing work in trauma applications. The company remains focused on craniomaxillofacial implants.

LithaBone HA 480 and production at scale

KLS Martin’s ceramic implants have been produced on Lithoz CeraFab printers since 2015. The relationship between the two companies shaped the development of Lithoz’s latest material, LithaBone HA 480 — a hydroxyapatite formulation developed in direct response to feedback from KLS Martin and other clinical users of earlier bone substitute materials.

LithaBone HA 480 addresses several practical limitations of its predecessor. Maximum wall thickness increased to 10 mm, expanding the range of geometries viable for clinical use. The material also exhibits reduced overpolymerization and improved depth of cure, simplifying build parameter selection and stabilizing the manufacturing process. Shelf life extended tenfold, and part cleaning improved through a revised binder composition. Adem Aksu, Director of Development for Biomaterials at KLS Martin, described the results as a substantial step forward: “From mechanical properties over higher wall thickness to size and lattice structures, LithaBone HA 480 has convinced us of a considerable improvement compared to its predecessor.”

Production runs entirely in-house at KLS Martin, inside a Class 7 clean room that the company developed after identifying process sensitivity issues with an earlier standard setup. Material enters the clean room; the finished, sterilized, packaged implant exits. The ceramic line, described by Reinauer as KLS Martin’s “youngest child,” had already produced many hundreds of units and was growing at double-digit rates—a pace he said held even through recent economic disruptions.

The next scale challenge: regulatory acceptance

For KLS Martin, like many AM pioneers, the primary growth constraint was financial. European healthcare reimbursement structures have struggled to reflect the true cost of patient-specific ceramic implants, which require virtual surgical planning, material qualification, sintering, sterilization, and packaging before a single unit ships. Reinauer drew a pointed comparison: “No one is thinks about spending and extra €800 for the glass top when ordering the next car. But if you lose a part of your head and I offer you the same, €1,800 is considered too much.”

On the materials development frontier, KLS Martin and Lithoz were exploring surface activation techniques to improve cellular recruitment into large ceramic scaffolds—a biological ceiling that constrains implant size as much as machine-built volume does. “Our mother nature is really clever,” Reinauer said. “If they realize that there is no need because everything works well, they do not invest any energy in growing in that field.” The goal is to develop surface treatments that actively signal to cells to proliferate into the scaffold’s pore structure rather than waiting for mechanical cues.

Reinauer also addressed PEEK composite materials in passing, noting a structural limitation in additive approaches: FFF extrusion coats bioactive particles within the extruded rod, effectively sealing them from cellular access. Milling opens the surface and exposes those particles — a distinction that, in his view, currently limits the clinical utility of additively manufactured PEEK-ceramic composites compared to machined equivalents.

To manage the end-to-end workflow from imaging data to finished implant, KLS Martin built a surgeon-facing digital platform. Clinicians upload DICOM scan data, KLS Martin engineers review it and produce an initial virtual surgical plan, and an iterative review process follows — with case status visible to the surgeon throughout. “It’s like a Facebook for surgeons if they have a need for such a kind of indication,” Reinauer said. The platform currently covers CMF and upper extremity indications, with the company expanding its trauma offering.