1 Department for Imaging and Functional Musculoskeletal Research, Institute of Anatomy and Cell Biology, Paracelsus Medical University Salzburg and Nuremberg, Salzburg, Austria; Ludwig Boltzmann Institute for Arthritis and Rehabilitation, Paracelsus Medical University Salzburg and Nuremberg, Salzburg, Austria; Chondrometrics GmbH, Freilassing, Germany. Electronic address: wolfgang.wirth@pmu.ac.at.