1Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, 14424 Potsdam, Germany
2Julius Wolff Institute and Center for Musculoskeletal Surgery, Charité-Universitätsmedizin, Augustenburger Platz 1, 13353 Berlin, Germany
3Department of Mathematics and Computer Science, Freie Universität Berlin, Arnimallee 6, 14195 Berlin, Germany