BioTPMS

In the first research project of its kind Fraunhofer IWS scientists aim to apply the principle of "Triple Periodic Minimal Surfaces" (TPMS), well-known from nature, to develop advanced additively manufactured titanium bone implants with optimized bionic properties. TPMS are complex structures that span periodically shaped geometries with minimal surface area. By means of additive manufacturing processes, it is possible to produce structures that are both very light and highly resilient. They are ideally suited for load-bearing implants that remain permanently in the body, such as skull and jaw plates, intervertebral space maintainers, sacroiliac joint stiffeners, and dental posts. The feasibility proof within the project is based on an intervertebral space maintainer, known as cage, which is used, for example, for fusions of lumbar vertebral bodies.

The challenge is to numerically and visually recreate the sophisticated cell structures as adapted from nature, as well as to replicate them using additive processes, in such a way that they can be transferred to the specific application. "Graded TPMS structures are a superior alternative to conventional implants," emphasizes Dr.-Ing. Markus Wagner, Manager of the Group "Design and Special Processes" at the Fraunhofer IWS Dresden. "Our novel approach can produce optimized implant properties that are significantly better able to withstand the high biomechanical stresses - i.e. the forces acting horizontally and vertically - in the human body. At the same time, the nature-inspired implant surfaces generate higher biocompatibility by promoting the attachment, ingrowth and build-through behavior of the natural bone tissue structure and supporting blood flow behavior." Consequently, mimicking the local tissue stiffness differences within bone and the different cell sizes and types is a key task that the project team, together with SIGNUS Medizintechnik GmbH and ProCon Medizintechnik GmbH, is addressing from September 2021.