Biocompatible metal foams are osteoconductive if the pore sizes are in the range of 100-500 µm, allowing a bone ingrowth in the highly porous structure. Further, the surfaces of the implants within the pores are an important factor for the adhesion, proliferation and differentiation of cells. The combination of the space holder method (SHM) with the metal injection molding (MIM) process is highly attractive for the near-net-shape production of porous NiTi components. The MIM process with pre-alloyed NiTi powder avoids the expensive and difficult thermomechanical working, the machining, and the high losses of the shape memory starting material. The SHM guarantees a well defined pore size distribution with total porosities up to 70%.

The production route of the near-net-shape NiTi components is discussed. The shape memory effect is demonstrated by differential scanning calorimetry (DSC) measurements and by mechanical compression tests exemplarily for samples with 50% porosity and pore sizes in the range of 355-500 µm. Cell culture tests with human mesenchymal stem cells (hMSCs) were done on those samples to discuss the biocompatibility of porous, powder metallurgically produced NiTi. Additionally, the influence of the starting powder size on the surface properties of the material and on the biocompatibility for hMSCs were examined.