*Article* **Mechanically Stable** β**-TCP Structural Hybrid Scaffolds for Potential Bone Replacement**

**Matthias Ahlhelm 1,\*, Sergio H. Latorre 2, Hermann O. Mayr 2, Christiane Storch 3, Christian Freytag 4, David Werner 4, Eric Schwarzer-Fischer <sup>4</sup> and Michael Seidenstücker 2,\***


**Abstract:** The authors report on the manufacturing of mechanically stable β-tricalcium phosphate (β-TCP) structural hybrid scaffolds via the combination of additive manufacturing (CerAM VPP) and Freeze Foaming for engineering a potential bone replacement. In the first step, load bearing support structures were designed via FE simulation and 3D printed by CerAM VPP. In the second step, structures were foamed-in with a porous and degradable calcium phosphate (CaP) ceramic that mimics porous *spongiosa*. For this purpose, Fraunhofer IKTS used a process known as Freeze Foaming, which allows the foaming of any powdery material and the foaming-in into near-net-shape structures. Using a joint heat treatment, both structural components fused to form a structural hybrid. This bone construct had a 25-fold increased compressive strength compared to the pure CaP Freeze Foam and excellent biocompatibility with human osteoblastic MG-63 cells when compared to a bone grafting Curasan material for benchmark.

**Keywords:** Freeze Foam; hybrid bone; biocompatibility; bone replacement
