1. Institute of Technical Medicine (ITeM), Furtwangen University, 78054 Villingen-Schwenningen, Germany
2. Innovation Center Computer Assisted Surgery (ICCAS), University of Leipzig, 04103 Leipzig, Germany
3. Department of Mechanical Engineering, University of Canterbury, Christchurch 8041, New Zealand
4. Department of Microsystems Engineering, University of Freiburg, 79110 Freiburg, Germany