Researchers at RWTH Aachen University’s Chair Digital Additive Production (DAP), working with the reACT alliance, are developing bioresorbable implants designed to fit each patient’s needs.
The initiative is supported by the German Federal Ministry of Education and Research (BMBF) under the “RUBIN – Regional Entrepreneurial Alliances for Innovation” program.
When severe bone damage results from injuries, congenital conditions, or tumor removal, reconstructive procedures often require implants to restore function. Conventional metal implants, such as titanium, provide structural support but can lead to complications like stress shielding, where the surrounding bone weakens over time.
On top of that, follow-up surgeries to take them out add to both recovery time and medical costs. Consequently, the project focuses on treating critical bone defects by designing implants that gradually dissolve in the body, reducing the need for follow-up surgeries and addressing the challenges associated with permanent metal implants.
Contributions for the project also came from Meotec, Medical Magnesium, Fibrothelium, University Hospital Aachen, and the Fraunhofer Institute for Laser Technology (ILT).
Optimized implant fit with automated design
A key part of this approach is a design configurator, an automated tool that generates implant models based on medical imaging data. It takes into account factors such as the shape of the defect, the patient’s age, and bone density to create a custom design suited for 3D printing with powder bed laser beam (PBF-LB) technology.
Once the shape of the implant is determined, its internal structure is adjusted to help guide bone regrowth. The design incorporates lattice structures, fine, repeating geometric patterns, that provide temporary support while allowing the implant to degrade evenly.
At the same time, the lattice structure is adapted to match the mechanical forces acting on the bone, reducing the chances of complications like refractures.
Selecting the right material is also key. Zinc and magnesium have properties that make them promising choices for bioresorbable implants, but each comes with challenges. Zinc degrades at a controlled rate but lacks the necessary strength for bone support.
On the other hand, Magnesium is strong enough but breaks down too quickly in certain conditions, sometimes causing gas formation in surrounding tissue. Now, by testing different alloy compositions, the research team identified a zinc-magnesium blend containing up to 1% magnesium as the best candidate for use in these implants.
A prototype implant has already been produced, specifically designed to match a patient’s long bone defect. The implant was 3D printed with a cylindrical structure, and its internal lattice features were automatically adjusted based on the patient’s specific requirements.
According to the researchers, these design elements can be fine-tuned, including the size and arrangement of the lattice, to optimize how the implant interacts with the surrounding bone.
Although this project is currently focused on long bone defects, the approach could also be applied to other areas of medicine, such as spinal implants or reconstructive procedures in the face and jaw.
Advanced bone generation with 3D printed implants
Bone implants have come a long way since integrating 3D printing for their development. This has led to patient-specific designs that support natural bone regeneration, eliminate removal surgeries, reduce complications, lower healthcare costs, and integrate biocompatible materials that safely degrade over time.
A notable contribution came from 3D printed implant developer Osteopore partnered with Maastricht University Medical Centre (UMC+) to develop a 3D printed bioresorbable bone implant designed to prevent lower leg amputations. The implant, a personalized cage structure, was created using Osteopore’s proprietary 3D printing technology and customized based on CT scans.
Made from FDA-approved polycaprolactone (PCL), it mimics the mechanical properties of trabecular bone and gradually degrades into water and carbon dioxide. Engineered to encourage bone regrowth, the implant was successfully implanted in its first patient in the Netherlands, with promising early results.
In another news, researchers at the University of New South Wales (UNSW) introduced a method for 3D printing bone-like structures containing living cells, which could be applied in bone tissue engineering, disease studies, and drug testing.
Associate Professor Kristopher Kilian, along with Dr. Iman Roohani from UNSW’s School of Chemistry, developed a technique that allows a ceramic-based ink to be printed directly into damaged areas, potentially supporting cartilage and bone reconstruction. The approach makes it possible to print cell-containing structures at room temperature for the first time, offering a different way to create materials that may aid in regenerative medicine and biomedical research.
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Featured image shows successfully manufactured demonstrator for the treatment of a critical tubular bone defect. Image via RWTH Aachen.
